Increased Radiographic Posterior Tibial Slope Is Associated With Subsequent Injury Following Revision Anterior Cruciate Ligament Reconstruction

A Novel Assessment of Sagittal Proximal Tibial Morphology and Relationship to Proximal Posterior Tibial Slope: Lateral Supratubercle Angle

BACKGROUND

Multiple techniques have been utilized to measure posterior tibial slope (PTS) without consensus on which imaging modality, view, and axis combination is most consistent for risk assessment and preoperative planning in primary and revision anterior cruciate ligament (ACL) surgery. An exclusively proximal-based measurement of PTS has yet to be defined.

PURPOSE/HYPOTHESIS

The purpose of this study was to establish normal values for novel measurements of sagittal proximal tibial morphology, the lateral supratubercle angle (LSTA) and the lateral supratubercle distance (LSTD), in normative and primary ACL tear cohorts. The secondary aim was to establish cutoff values and determine if these tibial measurement values are predictive of the presence of an ACL tear. It was hypothesized that LSTA will be significantly different between cohorts.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

The medical records of patients with a knee complaint between August 2016 and June 2024 were retrospectively reviewed, and the patients were placed into either the normative or primary ACL tear cohort. Three independent observers measured LSTA, LSTD, and PTS along both the lateral (L) and medial (M) tibial plateaus on standard lateral knee radiographs. Means were calculated for each measurement and compared between groups. The receiver operating characteristic curve was used to determine the sensitivity and specificity of significant measurements.

RESULTS

Significant differences were found between normative (n = 150) and primary ACL tear (n = 150) groups in LSTA-L (normative: 9.9°± 4.4° vs primary ACL tear: 11.1°± 4.4°; P = .02), LSTA-M (normative: 10.3°± 4.4° vs ACL tear: 11.4°± 4.6°; P = .03), and PTS-M (normative: 9.2°± 3.2° vs primary ACL tear: 10.0°± 3.1°; P = .03).

CONCLUSION

Mean values and ranges for LSTA and LSTD have been established in normative and primary ACL tear cohorts. LSTA-L, LSTA-M, and PTS-M significantly differed between the cohorts. Future studies with LSTA will evaluate the utilization of these proximal tibial deformity-based measurements in ACL surgery, retear risk assessment, and slope-reducing osteotomy planning.

Increased Lateral Posterior Tibial Slope Is Associated With a Greater Rate of Lateral Meniscal Injury in Acute Noncontact Anterior Cruciate Ligament Ruptures

PURPOSE

To determine whether there is an association between increasing posterior tibial slope and meniscal tears in a group of patients with isolated, noncontact and acute anterior cruciate ligament (ACL) ruptures from a large ACL registry.

METHODS

Our institution's ACL Registry was consulted to identify patients between the age of 18 and 45 years who underwent primary ACL reconstruction between January 2019 and July 2022 for acute, noncontact ACL rupture. Patients with pre-existing meniscal pathology, chronic ACL reconstructions, revisions, and multiligament knee injuries were excluded. Preoperative magnetic resonance imaging scans were used to measure lateral and medial posterior tibial slope. Meniscal injuries seen during arthroscopy were recorded on the basis of operative reports. Independent cohorts were created on the basis of the presence or absence of a meniscal tear. Two-tailed Student t tests were used to compare average medial and lateral posterior tibial slopes between groups. Separate analyses were performed for the presence of isolated lateral meniscal tears, isolated medial meniscal tears, and both medial and lateral meniscal tears. Multivariable logistic regression models were generated to evaluate other potential risk factors for each tear outcome, including age, sex, and body mass index (BMI). Receiver operating characteristic curve analysis was conducted to explore the potential of identifying an optimal threshold for predicting the presence of a meniscal tear based on lateral posterior tibial slope.

RESULTS

In total, 1,056 patients ultimately met inclusion criteria. There were 498 (47%) patients with any meniscal tear, 346 (33%) patients with lateral meniscus tears, 245 (23%) patients with medial meniscus tears, and 93 (9%) patients with both medial and lateral tears. The average lateral and medial posterior tibial slopes were 5.5° (-4.2° to 13.4°) and 5.7° (0° to 15.7°), respectively. Increased lateral tibial slope was associated with a statistically significant increase in rate of any meniscal tear (adjusted odds ratio 1.10, 95% confidence interval 1.04-1.16, P < .001) and lateral meniscal tear, specifically (adjusted odds ratio 1.11, 95% confidence interval 1.04-1.18, P < .001). In regression analysis, male sex and body mass index ≥35 were found to increase the risk of all meniscal tear types. With a receiver operating characteristic curve analysis identifying lateral posterior tibial slope threshold values that resulted area under the curve ranges from 0.55 to 0.57, we were unable to identify an optimal threshold for posterior tibial slope in predicting meniscal tears.

CONCLUSIONS

In this single-institution, registry-based study, increasing lateral posterior tibial slope was associated with a greater rate of meniscus injury in acute ACL ruptures, whereas medial tibial slope demonstrated no correlation. No optimal threshold of posterior slope could be identified above which the odds of a meniscal tear were significantly elevated. Regression analysis identified BMI ≥35 and male sex as independent risk factors for meniscal tear in this select population.

LEVEL OF EVIDENCE

Level III, comparative retrospective case series.

Guided Growth for Posterior Tibial Slope Correction Followed by ACL Reconstruction in an Adolescent Male: A Case Report

CASE

A 13-year-old adolescent boy presented with chronic anterior cruciate ligament (ACL) insufficiency and prior medial meniscectomy. Radiographic evaluation revealed a posterior tibial slope (PTS) of 20°, putting him at high risk of reinjury following ACL reconstruction (ACLR). Guided growth using anteriorly placed eight plates was used for 9 months, which reduced his PTS to 6°. Two months following plate removal, the patient underwent ACLR with lateral extra-articular tenodesis.

CONCLUSION

This previously proposed but never reported approach suggests that guided growth is a viable option to correct excessive PTS before ACLR in skeletally immature patients.

Mathematical explanations for knee osteotomies: "Dear engineer, how would you explain it in a simple way?"

INTRODUCTION

Knee osteotomies are effective procedures to treat different deformities and to redistribute the load at the joint level, reducing the risk of wear and, consequently, the need for invasive procedures. Particularly, knee osteotomies are effective in treating early arthritis related to knee deformities in young and active patients with high functional demands, with excellent long-term results. Precise mathematical calculations are imperative during the preoperative phase to achieve tailored and accurate corrections for each patient and avoid complications, but sometimes those formulas are challenging to comprehend and apply.

METHODS

Four specific questions regarding controversial topics (planning methods, patellar height, tibial slope, and limb length variation) were formulated. An electronic search was performed on PubMed and Cochrane Library to find articles containing detailed mathematical or trigonometrical explanations. A team of orthopedic surgeons and an engineer summarized the available Literature and mathematical rules, with a final clear mathematical explanation given by the engineer. Wherever the explanation was not available in Literature, it was postulated by the same engineer.

RESULTS

After the exclusion process, five studies were analyzed. For three questions, no studies were found that provided mathematical analyses or explanations. Through independent calculations, it was demonstrated why Dugdale's method underestimates the correction angle compared to Miniaci's method, and it was shown that the variation in patellar height after osteotomy can be predicted using simple formulas. The five included studies examine postoperative variations in limb length and tibial slope, providing formulas applicable in preoperative planning. New formulas were independently computed, using the planned correction angle and preoperatively obtained measurements to predict the studied variations.

CONCLUSIONS

There is a strict connection among surgery, planning, and mathematics formulas in knee osteotomies. The aim of this study was to analyze the current literature and provide mathematical and trigonometric explanations to important controversial topics in knee osteotomies. Simple and easy applicable formulas are provided to enhance the accuracy and outcomes of this surgical procedure.

Association Between Posterior Tibial Slope and ACL Injury in Pediatric Patients: A Systematic Review and Meta-analysis

BACKGROUND

The posterior tibial slope (PTS) has been proposed to be a radiographic risk factor for anterior cruciate ligament (ACL) injury in adults. However, this has not been well established in pediatric patients.

PURPOSE

This systematic review and meta-analysis was performed to investigate any association between PTS and ACL tears in the pediatric population.

STUDY DESIGN

Systematic review and meta-analysis; Level of evidence, 4.

METHODS

A systematic review was performed to identify studies that examined the relationship between PTS, medial tibial slope (MTS), and lateral tibial slope (LTS) and ACL tears in children and adolescents aged ≤18 years. Full-text observational studies comparing PTS, MTS, and/or LTS values between pediatric (≤18 years of age) patients with and without ACL injury were included in this analysis. Review articles and case series were excluded. The authors calculated the mean difference (MD) via a restricted maximum-likelihood estimator for tau square and a Hartung-Knapp adjustment for random-effects model.

RESULTS

A total of 348 articles were identified in the initial database search, yielding 10 for final inclusion and analysis. There was no statistically significant association between PTS (MD, 1.13°; 95% CI, -0.55° to 2.80°; P = .10), MTS (MD, 0.36°; 95% CI, -0.37° to 1.10°; P = .27), or LTS (MD, 1.41°; 95% CI, -0.20° to 3.02°; P = .075) and risk for ACL injury in this population.

CONCLUSION

The current study found that unlike what has been shown in adult populations, increased PTS may not be a significant risk factor for ACL tears in pediatric and adolescent patents. LTS was the only measured parameter that neared statistical significance, perhaps suggesting a potential role for this measurement in determining ACL risk if further research is done in this population.

An Update on Emerging Techniques and Considerations in Revision Anterior Cruciate Ligament Reconstruction

» The rate of primary anterior cruciate ligament reconstruction (ACLR) failure in at-risk populations remains unacceptably high and necessitates thorough evaluation of native alignment and concomitant injuries.» Posterior tibial slope of >12° is a substantial risk factor of ACLR failure and should be corrected through anterior closing wedge osteotomy.» Varus malalignment of >5° exacerbates stress on the ACL graft, increases ACLR failure risks, and should be considered for correction through high tibial osteotomy at the time of revision ACLR.» Injuries to the anterolateral ligamentous complex are prevalent in ACL ruptures, and high-risk patients have shown benefit from anterolateral ligament reconstruction or lateral extra-articular tenodesis in the revision setting.» Addressing posterolateral corner, collateral ligament, and meniscal injuries, during revision ACLR, is vital to mitigate increased graft forces and optimize knee stability and functional outcomes.

Younger age, hyperextended knee, concomitant meniscectomy and large prerevision anterior tibial translation are associated with graft failure after the revision anterior cruciate ligament reconstruction

Purpose

Graft failure following revision anterior cruciate ligament (ACL) reconstruction is higher than after primary ACL reconstruction. However, data regarding revision surgery is scarce. We aimed to evaluate the associated factors for failure after revision ACL reconstruction.

Methods

Fifty-four patients (mean age: 24.7 ± 10.0 years) who underwent revision ACL reconstruction at our hospital with ≥1 year follow-up were retrospectively examined. Patients were divided into Group F (graft failure) and Group N (no graft failure) groups. Univariate analysis was conducted to identify factors associated with graft failure. Receiver operating characteristic (ROC) curve analysis was performed to determine the optimal thresholds for differentiating between the two groups.

Results

Graft failure was observed in 7 of 54 patients (13.0%). In the univariate analysis, significant differences were observed for age at the initial surgery (Group F: 15.6 ± 1.5, Group N: 20.9 ± 8.1), age at the revision surgery (Group F: 18.0 ± 2.8, Group N: 25.7 ± 10.3), presence of hyperextended knee (Group F: 85.7%, Group N: 14.9%), concomitant meniscectomy (Group F: 42.9%, Group N: 14.9%), prerevision space for the ACL (sACL) (Group F: 7.2 ± 3.4 mm, Group N: 13.4 ± 4.7 mm) and preoperative anterior tibial translation (ATT) (Group F: 5.0 ± 1.4 mm, Group N: 2.7 ± 3.1 m). ROC analysis of preoperative sACL and preoperative ATT on one-leg standing plain radiograph showed that cutoff values of 6.9 and 4.2 mm were the optimal thresholds, respectively.

Conclusion

Younger patients with a hyperextended knee, concomitant meniscectomy, small sACL and large ATT before revision ACL reconstruction are predisposed to graft failure.

Level of Evidence

Level IV.

Supratubercle Anterior Closing Wedge Osteotomy: No Changes in Patellar Height and Significant Decreases in Anterior Tibial Translation at 6 Months Postoperatively

BACKGROUND

Because of the increased prevalence of revision anterior cruciate ligament (ACL) reconstruction, there has been a desire to understand the role of posterior tibial slope on increased anterior tibial translation and increased ACL graft forces. One potential concern in supratubercle anterior closing wedge proximal tibial osteotomy (ACW-PTO) for decreasing the posterior tibial slope is the risk of altering the patellar height.

PURPOSE

To radiographically assess changes in (1) patellar height, (2) anterior tibial translation, and (3) posterior tibial slope after supratubercle ACW-PTO.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Patients who underwent supratubercle ACW-PTO by a single surgeon between July 2019 and June 2023 were included. Standardized lateral knee weightbearing radiographs to assess patellar height (via the Caton-Deschamps index), anterior tibial translation of the lateral tibial plateau relative to the lateral femoral condyle, and posterior tibial slope were obtained at 4 time points (preoperatively and 1 day, 3 months, and 6 months postoperatively). Paired t test was used to compare differences between preoperative, 1-day, and 3- and 6-month values for patellar height as measured using the Caton-Deschamps index and for posterior tibial slope. Paired t test was also used to compare differences in the preoperative and 6-month postoperative values for anterior tibial translation.

RESULTS

In 20 patients after ACW-PTO, the Caton-Deschamps index demonstrated a significant increase in patellar height on postoperative day 1 (P < .001) but no significant differences at 3 (P = .057) and 6 (P = .176) months postoperatively. Anterior tibial translation on standing lateral knee radiographs was significantly decreased by a mean of 8.9 mm from preoperatively to 6 months postoperatively (P < .001). Posterior tibial slope was significantly decreased by a mean of 11.2° from preoperatively to 6 months postoperatively (P < .001).

CONCLUSION

Supratubercle ACW-PTO performed for ACL reconstruction failure in the setting of an increased posterior tibial slope did not induce significant changes in patellar height postoperatively. Furthermore, after ACW-PTO, there was a significant decrease in anterior tibial translation and posterior tibial slope.

Menta S, Ranawat AS. Systematic Review of Clinical Outcomes After Proximal Tibia Anterior Closing-Wedge Osteotomy With ACL Reconstruction

Background

While increased posterior tibial slope (PTS) is an important risk factor for failure after anterior cruciate ligament (ACL) reconstruction, controversy exists regarding indications and outcomes of proximal tibia anterior closing-wedge osteotomy (ACWO) with concomitant ACL reconstruction in patients with ACL tears.

Purpose

To assess clinical outcomes after combined ACL reconstruction and proximal tibia ACWO.

Study Design

Systematic review; Level of evidence, 4.

Methods

In accordance with PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) guidelines, we performed a systematic review of the existing literature on ACWO and ACL reconstruction using PubMed (MEDLINE), Cochrane Library, Scopus, and Embase. The search phrases included "anterior closing wedge osteotomy,""anterior closing wedge tibial osteotomy,""anterior closing wedge proximal tibial osteotomy,""anterior cruciate ligament," and "revision anterior cruciate ligament." Non-English publications and single-patient case reports were excluded. Extracted data included study details, patient demographics, patient-reported outcomes (PROs), clinical outcomes, radiographic outcomes, complications, and return-to-sport (RTS) rates.

Results

A total of 6 studies with 110 patients (110 knees) were included. Two-stage ACWO and ACL reconstruction was reported in 2 studies of 78 patients (71%), while a single-stage technique was reported in 4 studies of 32 patients (29%). ACWO was performed in the setting of primary ACL tear in 23 patients (21%) and in recurrent ACL tear in 87 patients (79%). Patients demonstrated postoperative improvements in Lysholm, pivot-shift test, and side-to-side difference in anterior tibial translation. After ACWO, all studies reported mean postoperative PTS of <10° (range, 4.4°-9.2°). Of patients with available RTS data (n = 43), the same-level RTS rate ranged from 65% to 100%. A two-stage procedure reported in 1 study had a lower RTS rate (n = 13 of 20 [65%]) than that of 2 studies with single-stage procedure (n = 4 of 5 [80%] and n = 18 of 18 [100%]). The overall complication rate was 0.9% to 1.3%, and there were no reported ACL retears.

Conclusion

The current evidence, which is constrained by the quantity and quality of studies, showed that ACWO with single- or two-stage ACL reconstruction in patients with ACL insufficiency and increased PTS was associated with significant improvements in PROs and high RTS rates.

Arthroscopic pullout repair versus suture anchor repair for medial meniscus posterior root tear combined with high tibial osteotomy

BACKGROUND

The aim of this study was to compare the outcomes of pullout repair with a metal button and suture anchor repair for medial meniscus posterior root tears in patients undergoing high tibial osteotomy with varus alignment.

METHODS

Patients who underwent arthroscopic pullout repair (P group) and suture anchor repair (SA group) in combination with open-wedge high tibial osteotomy between 2018 and 2021 were retrospectively examined. Patients who received second-look arthroscopy at 1 year and at least 2 years of follow up were included. Structural healing (complete/partial or failed healing) and chondral lesions at the initial surgery and the second-look arthroscopy, radiographic parameters around the knee, Lysholm score, and Tegner activity scale (before and 2 years after surgery) were compared.

RESULTS

A total of 88 patients (68 women/20 men, mean age 61.1 ± 7.9 years old) were included in the analysis. Of these, 51 patients underwent pullout repair, while the other 37 underwent suture anchor repair. The SA group showed a significantly higher rate of complete healing (64.9%) than the P group (21.6%, P < 0.001). The Lysholm score significantly improved after surgery in both treatment groups. At the final follow up, the SA group had a significantly higher Lysholm score (89.6 ± 10.7) than the P group (80.9 ± 17.4, P = 0.011).

CONCLUSION

Arthroscopic suture anchor repair had superior healing status and Lysholm Score in comparison with pullout repair with a metal button, as it achieved better tension adjustment. This result is meaningful particularly when medial meniscus root repair and high tibial osteotomy are performed simultaneously.

Intrarater and Interrater Reliability of Radiographic Characteristics in Skeletally Immature Patients With Anterior Cruciate Ligament Tears: A PLUTO Study Group Reliability Study

BACKGROUND

Radiographic measurements of limb alignment in skeletally immature patients with anterior cruciate ligament (ACL) tears are frequently used for surgical decision-making, preoperative planning, and postoperative monitoring of skeletal growth. However, the interrater and intrarater reliability of these radiographic characteristics in this patient population is not well documented.

HYPOTHESIS

Excellent reliability across 4 raters will be demonstrated for all digital measures of length, coronal plane joint orientation angles, mechanical axis, and tibial slope in skeletally immature patients with ACL tears.

STUDY DESIGN

Cohort study (diagnosis).

METHODS

Three fellowship-trained orthopaedic surgeons and 1 medical student performed 2 rounds of radiographic measurements on digital imaging (lateral knee radiographs and long-leg radiographs) of skeletally immature patients with ACL tears. Intrarater and interrater reliability for continuous radiographic measurements was assessed with intraclass correlation coefficients (ICCs) across 4 raters with 95% CIs for affected and unaffected side measurements. Interrater reliability analysis used an ICC (2, 4) structure and intrarater reliability analysis used an ICC (2, 1) structure. A weighted kappa coefficient was calculated for ordinal variables along with 95% CIs for both interrater and intrarater reliability. Agreement statistic interpretations are based on scales described by Fleiss, and Cicchetti and Sparrow: <0.40, poor; 0.40 to 0.59, fair; 0.60 to 0.74, good; and >0.74, excellent.

RESULTS

Radiographs from a convenience sample of 43 patients were included. Intrarater reliability was excellent for nearly all measurements and raters. Interrater reliability was also excellent for nearly all reads for all measurements.

CONCLUSION

Radiographic reliability of long-leg radiographs and lateral knee x-rays in skeletally immature children with ACL tears is excellent across nearly all measures and raters and can be obtained and interpreted as reliable and reproducible means to measure limb length and alignment.

LEVEL OF EVIDENCE

Level III.

Is the ratio of the index to ring finger length, a potential marker for prenatal testosterone-estrogen balance, related to posterior tibial slope?

BACKGROUND

The 2D:4D ratio, an indicator of prenatal testosterone-estrogen balance, is the index finger (second finger) size's ratio to the ring finger (fourth finger) size. Asymmetric growth in the proximal tibial growth plate is considered to cause the increased posterior tibial slope (PTS) formation. Factors determining the amount of this asymmetry still need clarification. This study aims to evaluate the relationship between the 2D:4D ratio, which indicates the prenatal testosterone-estrogen balance, and the PTS.

METHOD

Meeting the study criteria, 267 patients were included in the study. We measured the medial PTS (MPTS) and lateral PTS (LPTS) on MRI images and the lengths of the second and fourth fingers on both hands of the patients. Additionally, we compared 2D:4D ratios and MPTS and LPTS measurements.

RESULTS

We found a significant negative correlation between MPTS and the 2D:4D ratio, as well as between LPTS and the 2D:4D ratio in both hands (MPTS left vs. right hand: P < 0.001, r = -0.627 vs. P < 0.001, r = -0.498) (LPTS left vs. right hand: P < 0.001, r = 0.589 vs. P < 0.001, r = 0.404). Separately among males and females, there was a significant negative correlation between MPTS and the 2D:4D ratio, as well as between LPTS and the 2D:4D ratio in both hands (for males: MPTS left vs. right hand: P < 0.001, r = -0.607 vs. P < 0.001, r = -0.540)(for males: LPTS left vs.right hand: P < 0.001, r = 0.451 vs. P < 0.001, r = 0.406) (for females:MPTS left vs. right hand: P < 0.001, r = -0.638 vs. P < 0.001, r = -0.446) (for females:LPTS left vs.right hand: P < 0.001, r = 0.618 vs. P < 0.001, r = 0.403).

CONCLUSIONS

The 2D:4D ratio, an indicator of intrauterine testosterone-estrogen balance, is related to PTS. The effect of testosterone on the growth plate of the proximal tibia may be one of the factors determining the PTS value.

LEVEL OF EVIDENCE

III retrospective comparative study.

Posterior tibial slope (PTS) ≥ 10 degrees is a risk factor for further anterior cruciate ligament (ACL) injury; BMI is not

PURPOSE

This case-control study aimed to assess the influence of BMI and PTS on subsequent ACL injury affecting either ACL graft or the native ACL of the contralateral knee after primary ACL reconstruction.

METHODS

A retrospective case-control study was performed using a cohort of patients who underwent arthroscopic ACL reconstruction between 2010 and 2020 using the same surgical procedure: Hamstring tendon autograft. The study group (group I) included all the patients (n = 94) during this period who sustained a subsequent ACL injury. The control group (group II) consisted of 94 patients randomly selected (matched Group I in terms of sex, age, and ACL graft) who did not sustain any further ACL injury. PTS was measured by two blinded surgeons on lateral knee view radiographs of the operated knee after primary ACL. BMI in kg/m2 was measured during the preoperative anesthesia consultation. Exclusion criteria were: non-true or rotated lateral knee radiographs of the operated knee post-ACLR, associated knee ligament injury requiring surgical management, iterative knee surgeries, open growth plate, and related fracture.

RESULTS

The mean posterior tibial slope in group I was 7.5° ± 2.9, and 7.2° ± 2.0 in group II. A PTS angle cutoff was set at 10 degrees. The rate of patients showing a PTS ≥ 10° was significantly higher in group I compared to group II (p < 0.01). Patients with PTS ≥ 10° were 5.7 times more likely to sustain a subsequent ACL injury, (OR: 5.7 95% CI[1.858-17.486]). The Average BMI in group I was 24.5 ± 3.7 kg.m-2 compared to group II which was 23.3 ± 3.0 kg.m-2. There were no significant differences in any of the four BMI categories between both groups (p value 0.289). A series of BMI cut-offs were also analyzed at 23 to30 kg/m2, and there was no significant difference between both groups.

CONCLUSIONS

A posterior tibial slope equal to or above 10 degrees measured on lateral knee radiographs was associated with 5.7 times higher risk of ACL graft rupture or contralateral native ACL injury; however, BMI was not.

Development of Anatomic Risk Factors for ACL Injuries: A Comparison Between ACL-Injured Knees and Matched Controls

BACKGROUND

Several tibiofemoral anatomic features have been repeatedly associated with increased anterior cruciate ligament (ACL) injury risk. Previous studies have highlighted age and sex differences among these anatomic risk factors, but little is known about the normal and pathologic development of these differences during skeletal maturation.

PURPOSE

To investigate differences in anatomic risk factors at various stages of skeletal maturation between ACL-injured knees and matched controls.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

After institutional review board approval, magnetic resonance imaging scans from 213 unique ACL-injured knees (age, 7-18 years, 48% female) and 239 unique asymptomatic ACL-intact knees (age, 7-18 years, 50% female) were used to measure femoral notch width, posterior slope of the lateral and medial tibial plateau, medial and lateral tibial spinal height (MTSH, LTSH), medial tibial depth, and posterior lateral meniscus-bone angle. Linear regression was performed to assess change in quantified anatomic indices with age for male and female patients in the ACL-injured cohort. Two-way analysis of variance with Holm-Sidak post hoc testing was performed to compare anatomic indices between ACL-injured knees and ACL-intact controls in each age group.

RESULTS

In the ACL-injured cohort, notch width, notch width index and medial tibial depth increased with age (R2 > 0.1; P < .001) in both sexes. MTSH and LTSH increased with age only in boys (R2≥ 0.09; P≤ .001), whereas meniscus-bone angle decreased with age only in girls (R2 = 0.13; P < .001). There were no other age differences in quantified anatomic indices. Patients with ACL injury consistently had a significantly higher lateral tibial slope (P < .01) and smaller LTSH (P < .001) as compared with ACL-intact controls across all age groups and sexes. When compared with age- and sex-matched ACL-intact controls, ACL-injured knees had a smaller notch width (boys, 7-18 years; girls, 7-14 years; P < .05), larger medial tibial slope (boys and girls, 15-18 years; P < .01), smaller MTSH (boys, 7-14 years; girls, 11-14 years; P < .05), and larger meniscus-bone angle (girls, 7-10 years; P = .050).

CONCLUSION

The consistent morphologic differences throughout skeletal growth and maturation suggest a developmental role in high-risk knee morphology. The observed high-risk knee morphology at an earlier age preliminarily suggests the potential of knee anatomy measurements in identifying those with a predisposition toward ACL injury.

Posterior Tibial Slope in Patients Undergoing Bilateral Versus Unilateral ACL Reconstruction: MRI and Radiographic Analyses

BACKGROUND

An increased posterior tibial slope (PTS) is a risk factor for primary anterior cruciate ligament (ACL) tears and graft failure, but the PTS has not been well-defined in those who have experienced bilateral ACL injuries.

PURPOSE

The primary aim was to compare the PTS, as well as the rate of an elevated PTS (>12° on lateral radiography; >7° on magnetic resonance imaging [MRI]), between patients who have undergone bilateral ACL reconstruction (ACLR) versus unilateral ACLR. A secondary purpose was to examine whether these associations remained consistent on both plain radiography and MRI.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

We retrospectively identified patients who underwent primary ACLR at our institution from the years 2012 to 2020. Patients who underwent nonsimultaneous bilateral ACLR (n = 53) were matched to those who underwent unilateral ACLR (n = 53) by age, sex, and body mass index. Exclusion criteria were rotated lateral radiographs, MRI scans of inadequate quality, and concomitant ligament injuries or fractures. Those who had undergone unilateral ACLR with <5-year follow-up were further excluded. There were 3 blinded readers who measured the PTS on lateral radiographs, while the medial PTS (MPTS) and lateral PTS (LPTS) were measured on MRI scans. Bivariate regression was performed to determine the correlation between radiographic and MRI measurements.

RESULTS

The PTS on radiography (11.26° vs 10.13°, respectively; P = .044) and the LPTS on MRI (7.32° vs 6.08°, respectively; P = .012) in the bilateral ACLR group were significantly greater than those in the unilateral ACLR group but not the MPTS on MRI (4.55° vs 4.17°, respectively; P = .590). The percentage of patients in the bilateral group with a radiographic PTS >12° was 41.0% compared with 13.2% in the unilateral group (P = .012). The bilateral group had a significantly higher rate of an LPTS >7° compared with the unilateral group (53.8% vs 32.1%, respectively; P = .016) but not for an MPTS >7° (P = .190). On MRI, the LPTS (6.90°± 2.73°) was significantly greater than the MPTS (4.41°± 2.92°) (P < .001). There was a weak correlation between MPTS and radiographic PTS measurements (R = 0.24; P = .021), but LPTS and radiographic PTS measurements were not significantly correlated (R = 0.03; P = .810).

CONCLUSION

Patients who underwent bilateral ACLR had a significantly greater PTS on radiography and a significantly greater LPTS on MRI compared with those who underwent unilateral ACLR. The rate of a radiographic PTS >12° was 2.4 times greater among patients undergoing bilateral ACLR compared with those undergoing unilateral ACLR. PTS measurements on radiography demonstrated a weak to negligible correlation with PTS measurements on MRI, suggesting that future normative PTS values should be reported specific to the imaging modality.

Development and validation of a clinical tool to semi-automatic measure three-dimensional TAR alignment on two-dimensional radiographs

BACKGROUND

Malalignment is often postulated as an important reason for the high failure rate of total ankle replacements (TARs). The correlation between TAR malalignment and clinical outcome, however, is not fully understood. Improving and expanding radiographic TAR alignment measurements in the clinic might lead to a better insight into the correlation between malalignment and the clinical outcome. This study aims to develop and validate a tool to semi-automatic measure TAR alignment, and to improve alignment measurements on radiographs in the clinic.

METHODS

A tool to semi-automatically measure TAR alignment on anteroposterior and lateral radiographs was developed in MATLAB. Using the principle of edge contouring and the perpendicular relationship between the anteroposterior and lateral radiographs, the exact configuration of the TAR components can be found. Two observers validated the tool by measuring TAR alignment of ten patients using the tool. The Intraclass Coefficient (ICC) was calculated to assess the reliability of the developed method. The results obtained by the tool were compared to clinical results during radiographic follow-up in the past, and the accuracy of both methods was calculated using three-dimensional CT data.

RESULTS

The tool showed an accuracy of 76% compared to 71% for the method used during follow-up. ICC values were 0.94 (p < 0.01) and higher for both inter-and intra-observer reliability.

CONCLUSIONS

The tool presents a reproducible method to measure TAR alignment parameters. Three-dimensional alignment parameters are obtained from two-dimensional radiographs, and as the tool can be applied to most TAR designs, it offers a valuable addition in the clinic and for research purposes.

Association of Tibial Tubercle-Trochlear Groove Distance With Risk of ACL Graft Failure

Background

Limited evidence suggests a positive correlation between tibial tubercle-trochlear groove (TT-TG) distance and the risk of native anterior cruciate ligament (ACL) tear. The relationship between TT-TG distance and the risk of ACL graft failure is unknown.

Hypothesis

TT-TG distance is independently associated with risk of ACL graft failure.

Study Design

Cohort study; Level of evidence, 3.

Methods

All patients who underwent ACL revision surgery between 2010 and 2018 at a single institution were identified. A control cohort underwent primary ACL reconstruction (ACLR) between 2006 and 2015, with no evidence of graft failure at 8.1 ± 2.5 years postoperatively. Record review included anthropometrics, graft type, and estimated Tegner activity score at ≥6 months after primary ACLR. Magnetic resonance imaging (MRI) scans after native ACL tear (controls) or graft failure (revision cohort) were assessed for (1) TT-TG distance, (2) proximal tibial slopes, (3) depth of tibial plateau concavity, and (4) tunnel position (revision cohort). Associations between ACL graft failure and MRI measurements, surgical variables, and patient characteristics were evaluated with logistic regression analyses. Sensitivity analyses, excluding patients with tunnel malposition, were performed to confirm multivariable results in patients with "ideal" tunnel placement.

Results

Participants included 153 patients who underwent revisions and 144 controls. Controls were older than the patients who underwent revision (26.6 ± 8.8 vs 20.6 ± 7.3 years; P < .001). The mean TT-TG distance and lateral posterior tibial slope (PTS) were smaller for the control group than for the revision group (TT-TG: 9.3 ± 3.9 vs 11.2 ± 4.2 mm; P < .001; lateral PTS: 6.2° ± 3.3° vs 7.2° ± 3.6°; P = .01). TT-TG distance, lateral PTS, and age were associated with risk of ACL graft failure by multivariable analysis (OR, 1.15; 95% CI, 1.07-1.23; P < .001; OR, 1.13; 95% CI, 1.04-1.22; P = .004; and OR, 0.90; 95% CI, 0.87-0.94; P < .001, respectively). With sensitivity analyses, TT-TG distance, lateral PTS, and age at index surgery remained significantly and independently associated with ACL graft failure.

Conclusion

Increased TT-TG distance, increased lateral PTS, and younger age are independently associated with increased odds of ACL graft failure. Patients with these characteristics may require a more comprehensive strategy to reduce the risk of ACL reinjury.

Knee anatomic geometry accurately predicts risk of anterior cruciate ligament rupture

BACKGROUND

Certain anatomical characteristics of the knee have potential relationships with the risk of anterior cruciate ligament (ACL) rupture. There remains a need for stronger evidence using arthroscopy as well as radiological imaging to accurately clarify these relationships.

PURPOSE

To compare the anatomic geometry of the knee joint between patients with and without ACL ruptures.

MATERIAL AND METHODS

Case-controlled study of patients with arthroscopically confirmed ACL ruptures (ACL group) compared to patients with arthroscopically confirmed normal ACLs (control group). Magnetic resonance imaging scans were assessed for a total of 14 quantitative radiological variables including medial and lateral tibial slope angles (bone and cartilage measurements), meniscal height, femoral width, intercondylar notch width and tibial depth.

RESULTS

A total of 105 patients were included in the study, 55 in the ACL group and 50 in the control group. There was a significant difference (P < 0.05) of most of the radiological measurements between the two groups. There was also a significant difference (P < 0.05) when comparing the variables between sexes. Multiple logistic regression analysis produced a mathematical model utilizing all the radiological measurements with 92.6% classification accuracy in predicating an ACL rupture with the medial tibial slope angle being the strongest predicator variable (odds ratio = 8.97, P = 0.011).

CONCLUSION

Greater postero-inferior directed slope measurements of bone and cartilage in both the lateral and medial compartments with a narrower intercondylar notch width increase the risk of ACL rupture. Mathematical modelling can accurately predict the risk of ACL rupture.

Femoral condyle configuration and its impact on anterior cruciate ligament reconstruction

BACKGROUND

Rupture of the anterior cruciate ligament (ACL) is one of the most common knee injuries and has substantial impact on knee function. Beside primary ruptures, an increasing number of re-(re-)ruptures occur, representing a therapeutical challenge for the treating surgeon. Several risk factors for re-ruptures have been previously identified, including an increased tibial slope.

OBJECTIVE

In this study, we investigated the effect of femoral condyle configuration on ACL-ruptures and re-ruptures.

METHODS

In-vivo magnetic resonance imaging scans of three different groups of patients were compared. Group 1 included patients with an intact ACL on both sides, group 2 included patients with primary, unilateral ACL-rupture, while group 3 included patients with an ACL-re-rupture or re-(re-)rupture. Fourteen different variables were obtained and analyzed regarding their impact on ACL-re-(re-)rupture.

RESULTS

Overall, 334 knees were investigated. Our data allowed us to define parameters to identify anatomical configurations of bones associated with an increased risk of ACL-re-rupture. Our results show, that patients with ACL-re-rupture show increased radii of the extension facet of the lateral femoral condyle (p< 0.001) as well as of the extension facet of the medial femoral condyle (p< 0.001).

CONCLUSION

We conclude that a spherical femoral condyle form does influence the clinical outcome after ACL-reconstruction.

The Relationship Between Posterior Tibial Slope and Pediatric Tibial Eminence Fractures

BACKGROUND

Tibial eminence fractures are bony avulsions of the anterior cruciate ligament from its insertion on the intercondylar eminence. Numerous anatomic factors have been associated with anterior cruciate ligament injuries, such as posterior tibial slope, but there are few studies evaluating the association with tibial eminence fracture.

PURPOSE

To compare posterior tibial slope of pediatric patients with and without tibial eminence fractures. We hypothesized that a steeper posterior tibial slope would be associated with tibial eminence fracture.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Patients who underwent surgical treatment of tibial eminence fracture were retrospectively identified between January 2000 and July 2021. Adults aged >20 years and those without adequate imaging were excluded. Controls without gross ligamentous or osseous pathology were identified. Descriptive information and Meyers and McKeever classification were recorded. Posterior tibial slope measurements were obtained by 2 independent orthopaedic surgeons twice, with measurements separated by 3 weeks. Chi-square tests and independent-samples t tests were used to compare posterior tibial slope and patient characteristics. Inter- and intrareviewer variability was determined via the intraclass correlation coefficient.

RESULTS

A total of 51 patients with tibial eminence fractures and 57 controls were included. By sex, tibial eminence fractures occurred among 34 male and 17 female patients with a mean age of 10.9 years. The posterior tibial slope among those with tibial eminence fractures (9.7°) was not significantly greater than that of controls (8.8°; P = .07). Male patients with a tibial eminence fracture had significantly steeper slopes compared with controls (10.0° vs 8.4°; P = .006); this difference was not observed between female patients and female controls. Patients with a slope ≥1 SD above the mean (12.0°) had 3.8 times greater odds (95% CI, 1.3-11.6; P = .017) of having a tibial eminence fracture. Male patients with a posterior tibial slope >12° had 5.8 times greater odds (95% CI, 1.1-29.1; P = .034) of having a tibial eminence fracture compared with male controls.

CONCLUSION

Male patients undergoing surgical fixation of a tibial eminence fracture had an increased posterior tibial slope as compared with case-controls. Increased posterior tibial slope may be a risk factor for sustaining a tibial eminence fracture, although the clinical significance of this deserves further investigation.

High-grade preoperative osteoarthritis of the index compartment is a major predictor of meniscal allograft failure

INTRODUCTION

Preoperatively available predictors of meniscal allograft failure would help in patient counseling and surgical indication for meniscal allograft transplantation (MAT). It was hypothesized that young patient age, high posterior tibial slope (PTS), and high-grade osteoarthritis (OA) are predictors of meniscal allograft failure.

MATERIALS AND METHODS

Patients undergoing MAT with a minimum follow-up of 2 years were included in this retrospective study. Demographic and surgical data, and causes of meniscal allograft failure were collected. PTS and degree of OA (low-grade: Kellgren-Lawrence 0, 1, and 2; high-grade: Kellgren-Lawrence 3 and 4) of the index and opposite tibiofemoral compartments were determined on preoperative radiographs.

RESULTS

This study included 77 patients with a mean age of 25.7 ± 10.1 years at the time of MAT. After a mean follow-up of 7.6 ± 5.6 years, meniscal allograft failure was observed in 26 patients (34%). The median time from MAT to meniscal allograft failure was 1.3 years (inter-quartile range, 2.5 years). Meniscal allograft tears (88%) were the primary cause of graft failure, followed by high-grade OA (12%). Patients experiencing meniscal allograft failure were an average of 2.7 years (95% CI [2.2, 7.5], p = 0.202) older at the time of MAT than patients without failure. PTS was not found to be a predictor of meniscal allograft failure (odds ratio, 0.884 (95% CI [0.727, 1.073], p = 0.212)). Patients with high-grade preoperative OA of the index compartment had 28 times higher odds of experiencing meniscal allograft failure than patients with low-grade preoperative OA (p = 0.008).

CONCLUSIONS

High-grade preoperative OA of the index compartment was found to be a significant and clinically relevant predictor of meniscal allograft failure. Surgeons should be aware of the impact of OA on meniscal allograft survival, which needs to be considered in patient counseling and surgical indication for MAT in patients.

Association of Elevated Posterior Tibial Slope With Revision Anterior Cruciate Ligament Graft Failure in a Matched Cohort Analysis

BACKGROUND

Elevated posterior tibial slope (PTS) has been identified as an important risk factor in anterior cruciate ligament (ACL) injuries and ACL graft failures. The cutoff value to recommend treatment with slope-reducing osteotomy remains unclear and is based on expert opinion and small case series.

PURPOSE

(1) To determine whether there is a difference in PTS shown on lateral knee radiographs and magnetic resonance imaging (MRI) scans in a group of patients who experienced revision ACL graft failure versus a control group of patients who underwent successful revision ACL reconstruction, (2) to identify cutoff values of PTS measurements that predict risk of revision ACL graft failure, and (3) to examine whether there is a correlation between radiographic and MRI measurements of PTS.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

A total of 38 patients who experienced revision ACL graft failure were identified from a revision ACL database. These patients were matched 1:1 by age, sex, and graft type to a group of 38 control patients who underwent revision ACL reconstruction with no evidence of graft failure at a minimum 2 years of follow-up. Medial and lateral PTS were measured by lateral knee radiographs and MRI scans of the affected limb. Demographics, surgical characteristics, and PTS were compared between the groups. The optimal cutoff values of medial and lateral PTS per radiographs and MRI scans for predicting increased risk of revision ACL graft failure were determined by receiver operating characteristic curves. Conditional multivariable logistic regression was used to assess the relative contribution of PTS cutoff values as a predictor of revision graft failure.

RESULTS

The mean PTS values in the failure group were significantly higher than those in the control group on radiographs (medial, 13.2°± 2.9° vs 10.3°± 2.9°; P < .001; lateral, 12.9°± 3.0° vs 9.8°± 2.8°; P < .001) and MRI scans (medial, 7.2°± 3.1° vs 4.8°± 2.9°; P < .001; lateral, 8.4 ± 3.1° vs 5.9 ± 3.0°; P < .001). A radiographic medial PTS ≥14° had the highest increased risk of revision ACL graft failure with sensitivity equal to 50% and specificity to 92.1% (odds ratio, 18.71; 95% CI, 2.0-174.9; P = .01).

CONCLUSION

Elevated PTS was a significant risk factor for revision ACL graft failure. Patients with radiographic medial PTS ≥14° had 18.7-times increased risk of revision ACL failure.

Slope-decreasing anterior closing wedge proximal tibial osteotomies using the freehand technique are accurate to within 2̊

INTRODUCTION

Anterior cruciate ligament (ACL) reconstruction requires a detailed analysis of the posterior tibial slope (PTS) as excessive values may cause the reconstruction to fail and require a slope-decreasing anterior closing wedge tibial osteotomy combined with revision of the failed ACL reconstruction. The main purpose of this study was to assess the accuracy of correction after slope-decreasing anterior closing wedge tibial osteotomy in cases of chronic anterior instability caused by ACL rerupture.

MATERIALS AND METHODS

This single-center retrospective study included 19 patients (20 knees) operated on by slope-decreasing anterior closing wedge tibial osteotomy combined with a second revision ACL reconstruction. The mean age was 22.4±3.3 years and the mean follow-up was 12.7±4.4 months. The preoperative planning was based on lateral calibrated X-rays of the entire tibia. The height of the closing wedge, which corresponded to the base of the osteotomy, was measured in millimeters. The procedure was performed using the freehand technique. The accuracy of the correction was defined as the difference between the desired preoperative PTS and the postoperative PTS achieved. An inter- and intraobserver analysis was performed.

RESULTS

The mean preoperative PTS was 13.9±2̊ and the mean postoperative PTS was 4.0±1.7̊. The mean PTS correction was 10.1±2.1̊ with a planned target of 5.4±1.8̊. The accuracy obtained between the planned target and the postoperative corrections was 1.7±1.1̊. The regression analysis showed that the accuracy of the PTS correction was not influenced by the patient's age, BMI, excessive preoperative PTS, or degree of correction achieved (p>0.05).

CONCLUSION

Slope-decreasing anterior closing wedge tibial osteotomies performed using the freehand technique for ACL graft rerupture can correct an excessive PTS within 2̊ of the planned slope correction. This accuracy is not determined by demographic factors, excessive preoperative PTS or degree of correction achieved.

LEVEL OF EVIDENCE

IV; retrospective cohort study.

Anatomic Factors Associated With the Development of an Anterior Cruciate Ligament Rerupture in Men: A Case-Control Study

BACKGROUND

Although several factors are associated with anterior cruciate ligament (ACL) rerupture, the effect of anatomic factors associated with ACL rupture on ACL rerupture development has not been evaluated.

PURPOSE

To determine individual anatomic parameters independently associated with ACL rerupture and the diagnostic values of these parameters.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

A total of 91 male patients with ACL rerupture and 182 age-, sex-, body mass index-, and side dominance-matched patients without rerupture who underwent ACL reconstruction with a 5-year follow-up were included. In all, 35 parameters that were previously defined as risk factors for primary ACL rupture were compared between the 2 groups. Uni- and multivariate logistic regression models were created to evaluate independently associated factors. Receiver operating characteristic curve analysis was performed for independently associated parameters to predict sensitivity, specificity, and cutoff values.

RESULTS

The mean ± standard deviation age of patients at the time of index surgery was 26.5 ± 6.7 years. Notch shape index (P = .014), tibial proximal anteroposterior (AP) distance (TPAPD) (P < .001), lateral femoral condylar AP distance (LCAPD)/TPAPD ratio (P < .001), medial meniscal cartilage bone height (P < .001), and lateral meniscal bone angle (P = .004) were found to be significantly different between the 2 groups. Only the LCAPD/TPAPD ratio (odds ratio, 2.713; 95% CI, 1.998-5.480; P < .001) was found to be independently associated with ACL rerupture development. The LCAPD/TPAPD ratio revealed 78.9% sensitivity and 75.5% specificity (area under the curve, 0.815; 95% CI, 0.760-0.870) for values above 1.52.

CONCLUSION

The LCAPD/TPAPD ratio can be used to distinguish patients who are at risk of developing ACL rerupture from patients who are not. In the clinical practice, findings of this study may help to develop surgical and nonsurgical preventive strategies in ACL rerupture development.

Low posterior tibial slope is associated with increased risk of PCL graft failure

PURPOSE

To evaluate the effect of posterior tibial slope (PTS) on patient-reported outcomes (PROs) and posterior cruciate ligament (PCL) graft failure after PCL reconstruction.

METHODS

Patients undergoing PCL reconstruction with a minimum 2-year follow-up were included in this retrospective cohort study. A chart review was performed to collect patient-, injury-, and surgery-related data. Medial PTS was measured on preoperative lateral radiographs. Validated PROs, including the International Knee Documentation Committee Subjective Knee Form, Knee injury and Osteoarthritis Outcome Score, Lysholm Score, Tegner Activity Scale, and Visual Analogue Scale for pain, were collected at final follow-up. A correlation analysis was conducted to assess the relationship between PTS and PROs. A logistic regression model was performed to evaluate if PTS could predict PCL graft failure.

RESULTS

Overall, 79 patients with a mean age of 28.6 ± 11.7 years and a mean follow-up of 5.7 ± 3.3 years were included. After a median time from injury of 4.0 months, isolated and combined PCL reconstruction was performed in 22 (28%) and 57 (72%) patients, respectively. There were no statistically significant differences in PROs and PTS between patients undergoing isolated and combined PCL reconstruction (non-significant [n.s.]). There were no significant correlations between PTS and PROs (n.s.). In total, 14 (18%) patients experienced PCL graft failure after a median time of 17.5 months following PCL reconstruction. Patients with PCL graft failure were found to have statistically significantly lower PTS than patients without graft failure (7.0 ± 2.3° vs. 9.2 ± 3.3°, p < 0.05), while no differences were found in PROs (n.s.). PTS was shown to be a significant predictor of PCL graft failure, with a 1.3-fold increase in the odds of graft failure for each one-degree reduction in PTS (p < 0.05).

CONCLUSIONS

This study showed that PTS does not affect PROs after PCL reconstruction, but that PTS represents a surgically modifiable predictor of PCL graft failure.

LEVEL OF EVIDENCE

III.

Anterior Closing Wedge Osteotomy for Failed Anterior Cruciate Ligament Reconstruction: State of the Art

The sagittal anatomy of the proximal tibia has a bearing on the forces exerted on the cruciate ligaments. A high posterior tibial slope is now a well-known risk factor causing failure of anterior cruciate ligament (ACL) reconstructions. The posterior slope can be calculated on short or full-length radiographs, MRI scans, or three-dimensional CT scans. Reducing the slope surgically by a sagittal tibial osteotomy is biomechanically protective for the ACL graft. An anterior closing wedge osteotomy may be contemplated when the lateral tibial slope is greater than 12°, in the setting of ACL reconstruction failure(s). Careful surgical planning to calculate the correction, taking into account knee hyperextension and patella height, is critical to avoid complications. It can be done above, at, or below the tibial tuberosity level. A transtuberosity correction can be done with or without a tibial tubercle osteotomy. This complex surgery can be conducted safely by meticulous execution to protect the posterior hinge and neurovascular structures and achieving stable fixation with staples. The limited literature available justifies the usage of anterior closing wedge osteotomy in appropriately selected patients.

Differentiation in Posterior Tibial Slope by Sex, Age, and Race: A Cadaveric Study Utilizing 3-Dimensional Computerized Tomography

BACKGROUND

Posterior tibial slope (PTS) has recently gained increased attention for its possible role in anterior cruciate ligament and posterior cruciate ligament injury. The possible differences among age, sex, and ethnicity in PTS have not yet been reported.

PURPOSE

To describe demographic variances of proximal tibial anatomy and to detect differences in regard to ethnicity, sex, and age.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

In total, 250 cadaveric specimens with full-body computerized tomography scans from the New Mexico Descendant Imaging Database were randomly selected (inclusion/exclusion criteria: older than 18 years, complete imaging of the knee without previous surgery or arthroplasty) and reviewed by 3 independent observers measuring medial posterior tibial slope (MPTS), lateral posterior tibial slope (LPTS), and global posterior tibial slope (PTS), which was calculated as the mean of the MPTS and LPTS. Individuals were evenly divided among male and female and ethnicities/races: African American/Black, Asian American, Hispanic, Native American, and White. Intraclass correlation coefficient was calculated for interobserver reliability and analysis of variance statistical testing to determine statistical significance between groups. Fisher exact test was also used to understand PTS differences among ethnicities when looking at clinically significant values for potential ligamentous injury.

RESULTS

Measurements were obtained from 250 specimens with a mean age of 49.4 years (range, 19 to 103 years). The mean PTS was 8.92° (range, -9.4° to 14.95°). Asian Americans had a 1.7° greater mean MPTS than Whites (P = .016), and African Americans/Blacks had a 1.6° greater mean PTS than Whites (P = .022). No difference in mean PTS was seen between age and sex. When looking at clinically significant PTS, 61 (24.4%) individuals had tibial slopes <6° or >12°, 32 (12.8%) and 29 (11.6%), respectively. Statistically significant differences were seen among ethnicities with PTS <6° (P = .017) but not with PTS >12° (P = .106). No sex-based differences were seen in the percentage of specimens with a PTS of >12° or <6°.

CONCLUSION

Among ethnicities, African Americans/Blacks and Asian Americans have increased PTS in comparison with Whites. Nearly 25% of individuals have clinically significant slopes of <6° or >12°, with no difference in tibial slope among sex or age groups.

Tibial slope correction combined with second revision ACLR grants good clinical outcomes and prevents graft rupture at 7-15-year follow-up

PURPOSE

To update previously published outcomes (at 2-8 years) of second revision anterior cruciate ligament reconstruction (ACLR) combined with tibial deflexion osteotomy (TDO), after an interval of 5 more years (at 7-15 years), and monitor evolution of clinical scores and progression of osteoarthritis.

METHODS

The initial retrospective consecutive series included nine patients that underwent one-stage second revision ACLR with TDO, all of whom were contacted for second follow-up at minimum 7 years. An independent observer collected IKDC-SKF, the Lysholm score, and assessed radiographs for signs of osteoarthritis.

RESULTS

Of the nine original patients, seven were assessed at the clinic, one could only be assessed by telephone, and one was lost to follow-up. At final follow-up of 9.9 ± 3.0 years, the eight patients assessed maintained or improved clinical scores, compared to the previous follow-up at 4.0 ± 2.9 years. The mean Lysholm score improved from 73.8 ± 5.8 (65-82) to 84.5 ± 11.9 (59-95), and IKDC improved from 71.6 ± 6.2 (62-79) to 82.9 ± 12.1 (61-98). Of the three patients that had signs of arthritis at the previous follow-up, the stage of osteoarthritis increased in one (from grade 2 to grade 3), remained unchanged in one, and could not be assessed in one.

CONCLUSION

At 7-15 years following second revision ACLR with TDO, patients maintained or improved clinical scores compared to the previous follow-up at 2-8 years, without retears or reoperations. Although eight of the nine knees had meniscectomies or meniscal sutures, osteoarthritis progressed in only one of the six knees that had signs of arthritis at the previous follow-up. These results confirm that TDO can protect the ACL graft from retear, with minimal progression of osteoarthritis and/or risks of meniscal tears, suggesting that correction of excessive tibial slope should be considered when performing ACLR, whether a revision or primary procedure.

An increased posterior tibial slope is associated with a higher risk of graft failure following ACL reconstruction: a systematic review

PURPOSE

The posterior tibial slope (PTS) is considered a risk factor for anterior cruciate ligament (ACL) injury. However, the influence of PTS on graft failure following ACL reconstruction remains relatively unknown. Therefore, this systematic review was conducted to investigate whether PTS could be a potential risk factor for graft failure after ACL reconstruction.

METHODS

PubMed, EMBASE, Cochrane Library, Web of Science, China National Knowledge Infrastructure Database, and Wanfang Database were comprehensively searched from inception to March 31, 2021. Observational studies reporting the associations of medial tibial plateau slope (MTPS) or lateral tibial plateau slope (LTPS) with graft failure after ACL reconstruction were evaluated.

RESULTS

Twenty studies involving 12 case-control studies, 4 retrospective studies and 4 cross-sectional studies including 5326 patients met the final inclusion criteria. The high heterogeneity and the characteristics of nonrandomized controlled trials limited data synthesis. Fifteen of the 20 included studies detected a significant association between increased PTS and ACL graft failure, while 5 studies concluded that increased PTS was not associated with ACL graft failure. Ten studies suggested that MTPS is associated with ACL graft failure, and six studies suggested that LTPS is associated with ACL graft failure. The mean MTPS values for nonfailure group ranged from 3.5° ± 2.5° to 14.4° ± 2.8°. For the graft failure group, MTPS ranged from 4.71° ± 2.41° to 17.2° ± 2.2°. The mean LTPS values for nonfailure group ranged from 2.9° ± 2.1° to 11.9° ± 3.0°. For the graft failure group, LTPS ranged from 5.5° ± 3.0° to 13.3° ± 3.0°. The reported PTS values that caused ACL graft failure was greater than 7.4° to 17°.

CONCLUSION

Based on the current clinical evidence, increased PTS is associated with a higher risk of ACL graft failure after ACL reconstruction. Despite various methods of measuring PTS have high reliability, there is still vast disagreement in the actual value of PTS.

LEVEL OF EVIDENCE

IV.

Radiographic measurement of the posterior tibial slope in normal Chinese adults: a retrospective cohort study

Background

Measurement of the posterior tibial slope (PTS) angle has important applications in total knee replacement surgery, high tibial osteotomy, and anterior cruciate ligament reconstruction. This study aimed to determine the mean PTS of knee joints in healthy Chinese adults, and provide data to guide knee surgery in China.

Methods

A retrospective analysis of 1257 (n = 1233, 50.4% male) plain X-ray films of participants aged 25–59 years was performed. The picture archiving and communication system was used for PTS measurement. The PTS was defined as the angle between the vertical line of the tangent of the anterior tibial cortex of the proximal tibia, and the tangent line of the tibial cortex. Two imaging physicians conducted the PTS measurements independently, and both the inter- and intraclass correlation coefficients (ICCs) were calculated.

Results

The mean PTS value was 7.68 ± 3.84° (range: 0–21°). The left PTS was significantly smaller in males than in females (7.22 ± 3.89 vs 8.05 ± 3.60; P = 0.005). Additionally, the PTS in participants aged 25–29 years was significantly larger than that in the other age groups (Left side: 8.64 ± 3.73 vs 6.92 ± 3.42, 7.42 ± 3.75, 7.53 ± 3.98; P <  0.001 and Right side: 8.68 ± 3.84 vs 7.48 ± 4.21, 7.13 ± 3.64, 7.66 ± 3.80; P = 0.004). There were no significant differences in PTS between the left and right sides. Two-way analysis of variance suggested that the differences in PTS between age groups were not affected by sex. The interobserver ICC was 0.91 (95% confidence interval [CI]: 0.85–0.94), and the intraobserver ICC was 0.90 (95% CI: 0.82–0.94).

Conclusions

This study demonstrated that there were significant differences in PTS based on sex and age, highlighting the need to provide individualized treatment for knee surgery. It provided valuable information regarding the normal PTS values in Chinese adults and presented regionalised data to guide knee surgery.

Posterior Tibial Slope in Patients With Torn ACL Reconstruction Grafts Compared With Primary Tear or Native ACL: A Systematic Review and Meta-analysis

Background:

Increased posterior tibial slope (PTS) is a risk factor for anterior cruciate ligament (ACL) rupture and failure of ACL reconstruction (ACLR) grafts.

Purpose:

The purpose was to conduct a systematic review of literature on PTS measurements and to conduct a meta-analysis of comparable PTS measurements based on a patient’s ACL status. It was hypothesized that patients with torn ACLR grafts would have significantly larger medial and lateral PTS compared with patients with native ACLs or those who underwent primary ACLR.

Study Design:

Systematic review; Level of evidence, 4.

Methods:

A systematic review was performed using PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Included were studies that reported medial and/or lateral PTS measurements, those that reported PTS measurements based on ACL status (ie, intact ACL, primary ACL tear, failed ipsilateral ACLR, or revision ACLR), and those that reported their specific PTS measurement technique. Average PTS measurements, measurement location (medial or lateral tibial plateau) and technique, imaging modality used, and ACL status were extracted from each study. Data were pooled using DerSimonian and Laird random-effects models, and results were compared using the Altman interaction test.

Results:

The literature search identified 1705 studies, of which 82 (N = 12,971 patients) were included. There were 4028 patients in the intact ACL group (31%), 7405 in the primary ACLR group (57%), and 1538 in the failed ACLR group (12%). Measurements were obtained from lateral radiographs in 31 studies (38%), from magnetic resonance imaging in 47 studies (57%), and from computed tomography in 4 studies (5%). The failed ACLR group had a significantly larger lateral PTS (9.55°; 95% CI, 8.47°-10.63°) than either the primary ACL tear (7.13°; 95% CI, 6.58°-7.67°) or intact ACL (5.57°; 95% CI, 5.03°-6.11°) groups (P < .001 for both). The failed ACLR group also had a significantly larger medial PTS (9.05°; 95% CI, 7.80°-10.30°) than the primary (6.24°; 95% CI, 5.71°-6.78°) or intact ACL (6.28°; 95% CI, 5.21°-7.35°) groups (P < .001 for both).

Conclusion:

Both lateral and medial PTS measurements were greater in patients who had failed previous ACLR than those with a primary ACL tear or an intact native ACL. The lateral PTS of patients with primary ACL tears was greater than those with an intact native ACL.

ACL Size, but Not Signal Intensity, Is Influenced by Sex, Body Size, and Knee Anatomy

Background:

Little is known about sex-based differences in anterior cruciate ligament (ACL) tissue quality in vivo or the association of ACL size (ie, volume) and tissue quality (ie, normalized signal intensity on magnetic resonance imaging [MRI]) with knee anatomy.

Hypothesis:

We hypothesized that (1) women have smaller ACLs and greater ACL normalized signal intensity compared with men, and (2) ACL size and normalized signal intensity are associated with age, activity levels, body mass index (BMI), bicondylar width, intercondylar notch width, and posterior slope of the lateral tibial plateau.

Study Design:

Cross-sectional study; Level of evidence, 3.

Methods:

Knee MRI scans of 108 unique ACL-intact knees (19.7 ± 5.5 years, 62 women) were used to quantify the ACL signal intensity (normalized to cortical bone), ligament volume, mean cross-sectional area, and length. Independent t tests were used to compare the MRI-based ACL parameters between sexes. Univariate and multivariate linear regression analyses were used to investigate the associations between normalized signal intensity and size with age, activity levels, BMI, bicondylar width, notch width, and posterior slope of the lateral tibial plateau.

Results:

Compared with men, women had significantly smaller mean ACL volume (men vs women: 2028 ± 472 vs 1591 ± 405 mm³), cross-sectional area (49.4 ± 9.6 vs 41.5 ± 8.6 mm²), and length (40.8 ± 2.8 vs 38.1 ± 3.1 mm) (P < .001 for all), even after adjusting for BMI and bicondylar width. There was no difference in MRI signal intensity between men and women (1.15 ± 0.24 vs 1.12 ± 0.24, respectively; P = .555). BMI, bicondylar width, and intercondylar notch width were independently associated with a larger ACL (R² > 0.16, P < .001). Younger age and steeper lateral tibial slope were independently associated with shorter ACL length (R² > 0.03, P < .04). The combination of BMI and bicondylar width was predictive of ACL volume and mean cross-sectional area (R² < 0.3). The combination of BMI, bicondylar width, and lateral tibial slope was predictive of ACL length (R² = 0.39). Neither quantified patient characteristics nor anatomic variables were associated with signal intensity.

Conclusion:

Men had larger ACLs compared with women even after adjusting for BMI and knee size (bicondylar width). No sex difference was observed in signal intensity, suggesting no difference in tissue quality. The association of the intercondylar notch width and lateral tibial slope with ACL size suggests that the influence of these anatomic features on ACL injury risk may be partially explained by their effect on ACL size.

Registration:

NCT02292004 and NCT02664545 (ClinicalTrials.gov identifier).

A high tibial slope, allograft use, and poor patient-reported outcome scores are associated with multiple ACL graft failures

PURPOSE

To compare clinical outcomes, radiographic characteristics, and surgical factors between patients with single and multiple anterior cruciate ligament (ACL) graft failures. It was hypothesized that patients experiencing multiple ACL graft failures exhibit lower patient-reported outcome scores (PROs) and a higher (steeper) posterior tibial slope (PTS) than patients with single ACL graft failure.

METHODS

Patients undergoing revision ACL reconstruction with a minimum follow-up of 12 months were included in this retrospective cohort study. Based on the number of ACL graft failures, patients were assigned either to the group "single ACL graft failure "or" multiple ACL graft failures ". The PTS was measured on strict lateral radiographs. Validated PROs including the International Knee Documentation Committee (IKDC) subjective knee form, Knee Injury and Osteoarthritis Outcome Score, Lysholm Score, Tegner Activity Scale, ACL-Return to Sport after Injury Scale, and Visual Analogue Scale for pain were collected.

RESULTS

Overall, 102 patients were included with 58 patients assigned to the single ACL graft failure group and 44 patients to the multiple ACL graft failures group. Quadriceps tendon autograft was used significantly more often (55% vs. 11%, p < 0.001) and allografts were used significantly less often (31% vs. 66%, p < 0.001) as the graft for first revision ACL reconstruction in patients with single versus multiple ACL graft failures. Patients with multiple ACL graft failures were associated with statistically significantly worse PROs (IKDC: 61.7 ± 19.3 vs. 77.4 ± 16.8, p < 0.05; Tegner Activity Scale: 4 (range, 0-7) vs. 6 (range 2-10), p < 0.05), higher PTS (12 ± 3° vs. 9 ± 3°, p < 0.001), and higher rates of subsequent surgery (73% vs. 14%, p < 0.001) and complications (45% vs. 17%, p < 0.05) than patients with single ACL graft failure.

CONCLUSION

Compared to single ACL graft failure in this study multiple ACL graft failures were associated with worse PROs, higher PTS, and allograft use. During the first revision ACL reconstruction, it is recommended to avoid the use of allografts and to consider slope-reducing osteotomies to avoid multiple ACL graft failures and improve PROs.

LEVEL OF EVIDENCE

Level 3.

Quadriceps tendon autograft is becoming increasingly popular in revision ACL reconstruction

PURPOSE

To evaluate trends in revision anterior cruciate ligament reconstruction (ACL-R), with emphasis on intra-articular findings, grafts, and concurrent procedures. It was hypothesized that revision ACL-Rs over time show a trend toward increased complexity with increased use of autografts over allografts.

METHODS

This was a two-center retrospective study including patients undergoing revision ACL-R between 2010 and 2020. Demographic and surgical data including intra-articular findings and concurrent procedures were collected and compared for the time periods 2010-2014 and 2015-2020. All collected variables were compared between three pre-defined age groups (< 20 years, 20-30 years, > 30 years), right and left knees, and males and females. A time series analysis was performed to assess trends in revision ACL-R.

RESULTS

This study included 260 patients with a mean age of 26.2 ± 9.4 years at the time of the most recent revision ACL-R, representing the first, second, third, and fourth revision ACL-R for 214 (82%), 35 (14%), 10 (4%), and 1 (< 1%) patients, respectively. Patients age > 30 years showed a significantly longer mean time from primary ACL-R to most recent revision ACL-R (11.1 years), compared to patients age < 20 years (2.2 years, p < 0.001) and age 20-30 years (5.5 years, p < 0.05). Quadriceps tendon autograft was used significantly more often in 2015-2020 compared to 2010-2014 (49% vs. 18%, p < 0.001). A high rate of concurrently performed procedures including meniscal repairs (45%), lateral extra-articular tenodesis (LET; 31%), osteotomies (13%), and meniscal allograft transplantations (11%) was shown. Concurrent LET was associated with intact cartilage and severely abnormal preoperative knee laxity and showed a statistically significant and linear increase over time (p < 0.05). Intact cartilage (41%, p < 0.05), concurrent medial meniscal repairs (39%, p < 0.05), and LET (35%, non-significant) were most frequently observed in patients aged < 20 years.

CONCLUSION

Quadriceps tendon autograft and concurrent LET are becoming increasingly popular in revision ACL-R. Intact cartilage and severely abnormal preoperative knee laxity represent indications for LET in revision ACL-R. The high rate of concurrent procedures observed demonstrates the high surgical demands of revision ACL-R.

LEVEL OF EVIDENCE

Level III.

Determining the Ratio of Wedge Height to Degree of Correction for Anterior Tibial Closing Wedge Osteotomies for Excessive Posterior Tibial Slope

BACKGROUND

Anterior closing wedge osteotomy of the proximal tibia may be considered in revision anterior cruciate ligament (ACL) reconstruction surgery for patients with excessive posterior tibial slope (PTS).

PURPOSE

(1) To determine the ratio of wedge thickness to degrees of correction for supratubercle (ST) versus transtubercle (TT) osteotomies for anterior closing wedge osteotomies and (2) to evaluate the accuracy of ST and TT osteotomies in achieving slope correction.

STUDY DESIGN

Controlled laboratory study.

METHODS

The computed tomography (CT) scans of 38 knees in 37 patients undergoing revision ACL reconstruction were used to simulate both ST and TT osteotomies. A 10° wedge was simulated in all CT models. The height of the wedge along the anterior tibia was recorded for each of the 2 techniques. The ratio of wedge height to achieved degree of correction was calculated. ST and TT osteotomies were performed on 3-dimensional (3D)-printed tibias of the 12 patients from the study group with the greatest PTS, after the desired degree of correction was determined. Pre- and postosteotomy slopes were measured for each tibia, and the actual change in slope was compared with the intended slope correction.

RESULTS

According to CT measurements, the ratio of wedge height to degree of correction was 0.99 ± 0.07 mm/deg for the ST osteotomy and 0.83 ± 0.06 mm/deg for the TT osteotomy (P < .001). When these ratios were used to perform simulated osteotomies on the twelve 3D-printed tibias, the mean slope correction was within 1° to 2° of the intended slope correction, regardless of osteotomy location (ST or TT) or whether slope was measured on the medial or lateral plateau. The ST technique tended to undercorrect and the TT technique tended to overcorrect.

CONCLUSION

When anterior tibial closing wedge osteotomies were removed to correct excessive PTS, removing a wedge with a ratio of 1 mm of wedge height for every 1° of intended correction for an ST technique and a ratio of 0.8 mm to 1° for a TT technique resulted in overall average slope correction within 1° to 2° of the target.

CLINICAL RELEVANCE

The calculated ratios will allow clinicians to more accurately correct PTS when performing anterior closing wedge tibial osteotomy.

Effect of Time on MRI Appearance of Graft After ACL Reconstruction: A Comparison of Autologous Hamstring and Quadriceps Tendon Grafts

Background:

After anterior cruciate ligament (ACL) reconstruction (ACLR), changes in the appearance of the ACL graft can be monitored using magnetic resonance imaging (MRI).

Purpose:

The purpose of this study was to evaluate and compare the MRI signal intensity (SI) of hamstring and quadriceps tendon grafts during the first postoperative year after ACLR. As a secondary aim, the relationship of SI to clinical and anatomic measurements was analyzed.

Study Design:

Cohort study; Level of evidence, 2.

Methods:

A total of 78 patients who underwent ACLR with an autologous graft were reviewed; 55 received hamstring grafts and 23 received quadriceps tendon grafts. At 3 and 9 months postoperatively, 3-T MRI was performed using a dedicated knee coil, and the median SI of the intra-articular ACL graft was measured on sagittal-plane images. Postoperative lateral radiographs were analyzed to determine medial and lateral posterior tibial slope (PTS). Side-to-side difference in anterior knee laxity between injured and uninjured limbs was measured at 6 and 12 months postoperatively.

Results:

The median SI of quadriceps grafts was significantly greater than hamstring grafts at 3 months after ACLR (P = .02). Between 3 and 9 months, the median SI of quadriceps grafts decreased (P < .001), while that of hamstring grafts did not significantly change (P = .55). The lateral PTS was significantly correlated with median SI measurements at 3 and 9 months such that greater lateral PTS values were associated with greater median SI. The side-to-side difference in anterior knee laxity decreased for the quadriceps group (P = .04) between 6 and 12 months but did not change for the hamstring group (P = .88).

Conclusion:

The median SI of quadriceps grafts significantly decreased on MRI between 3 and 9 months after ACLR, while the median SI of hamstring grafts did not significantly change. The change in MRI appearance of the quadriceps grafts was paralleled by a reduction in anterior knee laxity between 6 and 12 months after surgery. In the absence of standardized imaging techniques and imaging analysis methods, the role of MRI in determining graft maturation, and the implications for progression through rehabilitation to return to sport, remain uncertain.

Plain Radiographs Can Safely Be Used to Measure and Follow Up on Tibial Component Alignment in Unicondylar Knee Replacement: A Correlation Study With CT Scans

Background and objective

Unicondylar knee replacement (UKR) is one of the most frequently performed arthroplastic operations worldwide. Migration and subsidence regarding the tibial component of UKR is a well-known phenomenon. In this study, we aimed to analyze whether plain radiographs are a reliable means to measure the true coronal and sagittal alignment of the UKR’s tibial component.

Methods

Patients undergoing a UKR procedure at our center between December 2020 and March 2011 were eligible for this study. Inclusion criteria were as follows: the presence of well-aligned standard and reproducible anteroposterior and lateral X-rays taken one week before or after a low-radiation artifact-reduced CT scan. Sixty-six knees were included in the study. Coronal and sagittal alignment of the tibial component was measured in a standard manner by two observers on both X-rays and CT scans. A correlation analysis was performed, and the margin of error was established.

Results

Intra-observer reliability was high among the two observers whether for X-ray or CT scan measurements [intraclass correlation coefficient (ICC): >0.900]. On the other hand, coronal plane measurements had lower inter-observer ICC values on both X-rays and CT scans while reliability on the sagittal plane was higher. There was a high correlation between radiographic measurements on X-rays and CT scans on both planes.

Conclusion

Even though the measurements on plain radiographs were slightly different from the ones obtained from CT scans, the correlation between them was very strong. Caution should be exercised when measuring the coronal alignment of the tibial implant on X-rays since it is more frequently affected by rotational misalignment.

Medial and Lateral Posterior Tibial Slope Are Independent Risk Factors for Noncontact ACL Injury in Both Men and Women

Background:

Higher posterior tibial slope (PTS) is a risk factor for anterior cruciate ligament (ACL) injury in men and women. The individual contribution of the lateral (LPTS) and medial (MPTS) slope has not yet been investigated.

Purpose:

To determine whether either the LPTS or the MPTS is an independent risk factor for ACL injury, and to determine sex-specific differences between patients with ACL-deficient and ACL-intact knees.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

We reviewed knee magnetic resonance (MR) images performed on ACL-deficient and ACL-intact knees between January 2018 and June 2020 at a single institution. Inclusion criteria were isolated ACL injury and noncontact mechanism (ACL-deficient group) and nonspecific knee pain and no history of injury (ACL-intact group). Exclusion criteria for both groups were the following: previous knee surgery; meniscal, collateral ligament, posterior cruciate ligament, or multiligamentous injuries; radiological evidence of osteoarthritis; and chondral damage on the tibia. The MR images were used to establish the posterior bony slope at 25%, 50%, and 75% from the medial and/or lateral border of the tibial plateau with respect to the proximal tibial anatomic axis. One-way analysis of variance (ANOVA) was used to determine differences in PTS at the 25%, 50%, and 75% distances for the medial and lateral tibial plateau between the groups and between the sexes.

Results:

Overall, 325 images were included (mean age, 36.1 ± 11.1 years; 142 ACL-deficient images [82 men and 60 women]; 183 ACL-intact images [112 men and 71 women]). MPTS and LPTS were significantly higher at 25%, 50%, and 75% in the ACL-deficient group (range, –2.7° to –5.7°) compared with the ACL-intact group (range, –2.1° to 1.5°; P = .00001). Similarly, MPTS and LPTS were significantly different in men versus women (P = .00001). ANOVA revealed that there were no significant differences in PTS between men and women for all measures (MPTS, LPTS, ACL-deficient, ACL-intact; P = .68).

Conclusion:

The study results demonstrated that higher MPTS and LPTS is a potential risk factor for ACL injury in both men and women. However, despite being highly statistically significant, the differences between groups and sexes were small and may not be clinically relevant.

The Intrarater and Inter-rater Reliability of Radiographic Evaluation of the Posterior Tibial Slope in Pediatric Patients

BACKGROUND

In young athletes, an association exists between an increased posterior tibial slope (PTS) and the risk of primary anterior cruciate ligament (ACL) injury, ACL graft rupture, contralateral ACL injury, and inferior patient reported outcomes after ACL reconstruction. In spite of this, there is no consensus on the optimal measurement method for PTS in pediatric patients. The purpose of this study was to evaluate the reliability of previously described radiographic PTS measurement techniques.

METHODS

A retrospective review was performed on 130 patients with uninjured knees between the ages of 6 and 18 years. The medial PTS was measured on lateral knee radiographs by four blinded reviewers using three previously described methods: the anterior tibial cortex (ATC), posterior tibial cortex (PTC), and the proximal tibia anatomic axis (PTAA). The radiographs were graded by each reviewer twice, performed 2 weeks apart. The intrarater and inter-rater reliability were assessed using the intraclass correlation coefficient (ICC). Subgroup analyses were then performed stratifying by patient age and sex.

RESULTS

The mean PTS were significantly different based on measurement method: 12.5 degrees [confidence interval (CI): 12.2-12.9 degrees] for ATC, 7.6 degrees (CI: 7.3-7.9 degrees) for PTC, and 9.3 degrees (CI: 9.0-9.6 degrees) for PTAA (P<0.0001). Measures of intrarater reliability was excellent among all reviewers across all 3 methods of measuring the PTS with a mean ICC of 0.87 (range: 0.82 to 0.92) for ATC, 0.83 (range: 0.82 to 0.87) for PTC, and 0.88 (range: 0.79 to 0.92) for PTAA. The inter-rater reliability was good with a mean ICC of 0.69 (range: 0.62 to 0.83) for the ATC, 0.63 (range: 0.52 to 0.83) for the PTC, and 0.62 (range: 0.37 to 0.84) for the PTAA. Using PTAA referencing, the PTS was greater for older patients: 9.9 degrees (CI: 7.7-9.4 degrees) vs 8.5 degrees (CI: 9.2-10.7 degrees) (P=0.0157) and unaffected by sex: 9.5 degrees (CI: 8.8-10.1 degrees) for females and 9.0 degrees (CI: 8.0-10.0) for males (P=0.4199). There were no major differences in intrarater or inter-rater reliability based on age or sex.

CONCLUSIONS

While the absolute PTS value varies by measurement technique, all methods demonstrated an intrarater reliability of 0.83 to 0.88 and inter-rater reliability of 0.61 to 0.69. However, this study highlights the need to identify PTS metrics in children with increased inter-rater reliability.

LEVEL OF EVIDENCE

IV, Case series.

The EOS 3D imaging system reliably measures posterior tibial slope

Background

One of the values determined during the assessment of knee issues is the posterior tibial slope (PTS). A new option for measuring the PTS is the EOS 3D imaging system, which provides anteroposterior (AP) and lateral long leg radiographs (LLRs) using less radiation than a conventional LLR. We investigated the reliability of the EOS 3D imaging system with respect to PTS measurements.

Methods

We retrospectively searched our radiological database for patients who underwent an EOS scan and a computed tomography (CT) scan of their lower extremities between January and December 2019. Fifty-six knees were included in the study. Medial and lateral PTSs were determined using both modalities. A radiologist and an orthopaedic surgeon each performed all measurements twice and the intraclass correlation (ICC) was calculated to assess inter- and intrarater reliability. The Student t test and Pearson correlation were used to compare the results of both imaging modalities.

Results

The mean medial PTS was 8.5° (95% confidence interval [CI], 8.1–8.9°) for the EOS system and 7.7° (95% CI, 7.3–8.1°) for CT, and the lateral PTS was 7.4° (95% CI, 6.9–7.9°) for the EOS system, and 7.0° (95% CI, 6.5–7.4°) for CT. Interrater reliability (ICC) with respect to medial and lateral PTSs measured on the EOS (0.880, 0.765) and CT (0.884, 0.887) images was excellent. The intrarater reliability of reader 1 (ICC range, 0.889–0.986) and reader 2 (ICC range, 0.868–0.980) with respect to the same measurements was excellent.

Conclusion

The PTS measurements from the EOS 3D imaging system are as reliable and reproducible as those from CT, the current gold standard method. We recommend using this system if possible, because it acquires more information (sagittal plane) in a scan than a conventional LLR, while exposing the patient to less radiation.

Level of evidence

Level III, Retrospective cohort study

Higher risk of contralateral anterior cruciate ligament (ACL) injury within 2 years after ACL reconstruction in under-18-year-old patients with steep tibial plateau slope

PURPOSE

To assess the role of Tibial Plateau Slope (TPS) as risk factor for early Anterior Cruciate Ligament (ACL) reconstruction failure and contralateral ACL injury in a population of patients with less than 18 years of age and operated on with the same surgical technique.

METHODS

Ninety-four consecutive patients (mean age 15.7 ± 1.5 years) with at least 2 years of follow-up, who underwent ACL reconstruction with a single-bundle plus lateral-plasty hamstring technique in the same centre were included. Subsequent ACL injuries (ipsilateral ACL revision or contralateral ACL reconstruction) were assessed within the first 2 years after surgery. Anterior, central, posterior TPS of medial compartment were measured on lateral radiographs and compared between patients with intact graft and those with a second injury. Cut-off values with sensitivity and specificity were calculated with receiver operating characteristic (ROC) analysis. Survival analysis for second ACL injuries and multivariate analysis were performed.

RESULTS

Eight patients (9%) had ipsilateral ACL Revision and eight patients (9%) had contralateral ACL reconstruction. Patients with contralateral injury had a higher Central TPS with respect to those without second injury (12.6° ± 2.8° vs 9.3° ± 3.7°, p = 0.042). No differences were present in patients with ipsilateral ACL revision. Sensitivity and specificity for central TPS slope ≥ 12° to detect a contralateral rupture were 63% and 75% (p = 0.0092), for Anterior TPS were 100% and 52% (p = 0.0009). Patients with TPS values exceeding these cut-offs had higher rate of contralateral ACL injuries (19%vs4%, p = 0.0420) and lower 2-year survival (p = 0.0049). Multivariate analysis identified pre-operative sport level and TPS (either anterior or central) as risk factors for contralateral injuries.

CONCLUSIONS

Steep tibial plateau slope ≥ 12° is associated with a higher risk of contralateral ACL injury within 2 years after ACL reconstruction in patients less than 18 years of age. However, TPS has no role in early ipsilateral re-injury after combined ACL reconstruction and lateral plasty. The clinical relevance is that both the surgeon and the patient should be aware of this higher risk and consider it in the rehabilitation phase to reduce the incidence of such injuries.

LEVEL OF EVIDENCE

III.

Steep medial tibial slope and prolonged delay to surgery are associated with bilateral medial meniscus posterior root tear

PURPOSE

Contralateral medial meniscus posterior root tear (MMPRT) can sometimes occur after primary surgeries for MMPRT and lead to unsatisfactory outcomes. The incidence rate and risk factors for contralateral MMPRT have not been well investigated, despite their clinical importance. Therefore, the incidence and predictors of bilateral MMPRT were aimed to be evaluated.

METHODS

Fourteen patients with bilateral MMPRT (group B) and 169 patients with unilateral MMPRT (group U) were enrolled in this study. Sex, age, body mass index, time between injury and surgery, and medial tibial slope angle (MTSA) were compared between the groups. MTSA was measured using lateral radiographs.

RESULTS

The incidence rate of bilateral MMPRT was 6.2% among all patients with MMPRTs. Multivariate logistic regression analysis showed that a prolonged time between injury and surgery (odds ratio [OR], 1.0; 95% confidence interval [CI] 1.00-1.01; P < 0.05) and steeper MTSA (OR, 1.85; 95% CI 1.21-2.64; P < 0.01) were significantly associated with the development of bilateral MMPRT. Receiver operating characteristic curve analysis showed that MTSA > 10.0° was associated with bilateral MMPRT, with a sensitivity of 93% and specificity of 69%.

CONCLUSION

A longer time between injury and surgery and steeper MTSA were risk factors for the development of bilateral MMPRT. Surgeons need to pay close attention to the contralateral knee in addition to the primary injured knees when treating knees with steep MTSA. Besides, early meniscal repair of primary MMPRT would be important to prevent the events of contralateral MMPRT.

LEVEL OF EVIDENCE

III.

Association Between Radiological Evidence of Kaplan Fiber Injury, Intraoperative Findings, and Pivot-Shift Grade in the Setting of Acute Anterior Cruciate Ligament Injury

BACKGROUND

Biomechanical studies have suggested that the Kaplan fibers (KFs) of the iliotibial band play a role in controlling anterolateral rotation of the knee. There is a paucity of clinical information on whether injury to the KF in the setting of anterior cruciate ligament (ACL) rupture contributes to increased rotatory laxity of the knee.

PURPOSE/HYPOTHESIS

The purpose was to evaluate the association among radiological evidence of KF injury, intraoperative arthroscopic findings, and grade of pivot shift at the time of ACL reconstruction (ACLR). It was hypothesized that KF injury would be associated with increased injury to the lateral compartment of the knee and a higher grade of pivot shift.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A retrospective magnetic resonance imaging (MRI) analysis was conducted on 267 patients with ACL-injured knees who underwent primary ACLR. Patients who had MRI and surgery within 60 days of injury were included (mean age, 23.6 years); there were 158 (59.2%) male patients. MRI was performed using standard knee protocols, and diagnostic criteria were applied to identify KF injury. Associations were made among MRI findings, intraoperative findings, and grade of pivot shift with the patient examined under anesthesia at the time of ACLR. A comparison was made between patients with and without radiological evidence of KF injury.

RESULTS

The prevalence of KF injury was 17.6% (47/267 patients). Arthroscopic evidence of lateral meniscal injury was associated with KF injury (KF intact, 31%; KF injured, 55%; P = .010). The majority of patients in the intact and injured KF groups had a grade 2 pivot shift (75% and 70%, respectively). A minority had grade 3 pivot shift: 5% in the intact group versus 6.4% in the injured group. There was no association between radiological evidence of KF injury and pivot-shift grade (P = .600).

CONCLUSION

In acute ACL injury, KF injuries were not very common (17.6%), and the rate of grade 3 pivot shift was low (5.2%). When present, KF injuries were not associated with a higher-grade pivot shift. However, there was an association between KF injury and lateral meniscal tears identified at the time of ACLR. The role of KFS in controlling anterolateral rotatory laxity in the acute ACL injury in the clinical setting may be less evident when compared with the biomechanical setting.

Risk Factors for Failure After Anterior Cruciate Ligament Reconstruction in a Pediatric Population: A Prediction Algorithm

Background:

Anterior cruciate ligament reconstruction (ACLR) in pediatric patients is becoming increasingly common. There is growing yet limited literature on the risk factors for revision in this demographic.

Purpose:

To (1) determine the rate of pediatric revision ACLR in a nationally representative sample, (2) ascertain the associated patient- and injury-specific risk factors for revision ACLR, and (3) examine the differences in the rate and risks of revision ACLR between pediatric and adult patients.

Study Design:

Case-control study; Level of evidence, 3.

Methods:

The PearlDiver patient record database was used to identify adult patients (age ≥20 years) and pediatric patients (age <20 years) who underwent primary ACLR between 2010 and 2015. At 5 years postoperatively, the risk of revision ACLR was compared between the adult and pediatric groups. ACLR to the contralateral side was also compared. Multivariate logistic regression was used to determine the significant risk factors for revision ACLR and the overall reoperation rates in pediatric and adult patients; from these risk factors, an algorithm was developed to predict the risk of revision ACLR in pediatric patients.

Results:

Included were 2055 pediatric patients, 1778 adult patients aged 20 to 29 years, and 1646 adult patients aged 30 to 39 years who underwent ACLR. At 5 years postoperatively, pediatric patients faced a higher risk of revision surgery when compared with adults (18.0 % vs 9.2% [adults 20-29 years] and 7.1% [adults 30-39 years]; P < .0001), with significantly decreased survivorship of the index ACLR (P < .0001; log-rank test). Pediatric patients were also at higher risk of undergoing contralateral ACLR as compared with adults (5.8% vs 1.6% [adults 20-29 years] and 1.9% [adults 30-39 years]; P < .0001). Among the pediatric cohort, boys (odds ratio [OR], 0.78; 95% CI, 0.63-0.96; P = .0204) and patients >14 years old (OR, 0.62; 95% CI, 0.45-0.86; P = .0035) had a decreased risk of overall reoperation; patients undergoing concurrent meniscal repair (OR, 1.84; 95% CI, 1.43-2.38; P < .0001) or meniscectomy (OR, 2.20; 95% CI, 1.72-2.82; P < .0001) had an increased risk of revision surgery. According to the risk algorithm, the highest probability for revision ACLR was in girls <15 years old with concomitant meniscal and medial collateral ligament injury (36% risk of revision).

Conclusion:

As compared with adults, pediatric patients had an increased likelihood of revision ACLR, contralateral ACLR, and meniscal reoperation within 5 years of an index ACLR. Families of pediatric patients—especially female patients, younger patients, and those with concomitant medial collateral ligament and meniscal injuries—should be counseled on such risks.

Autograft diameter in ACL reconstruction: size does matter

BACKGROUND

Anterior cruciate ligament injuries are commonly seen in orthopedic surgery practice. Although anterior cruciate ligament reconstruction (ACLR) has come a long way, the causes of failure have yet to be fully understood.

OBJECTIVE

The aim of this study was to investigate whether or not the intraoperative 4-strand hamstring autograft diameter does in fact influence the failure rates of ACLR.

METHODS

Retrospective intraoperative data were collected from ACLR patients from the only tertiary center available in Kuwait. Patients who underwent ACLR from 2012 to 2018 for isolated ACL injuries were included in this study, allowing for a 24 month follow-up period The cohorts were categorized into 3 groups: patients with graft size≤8mm, 2, patients with graft sizes≥8mm with 4-strands and patients with graft sizes≥8mm with 4-strands or more. ANOVA analysis was applied to address group differences between mean graft size and strand numbers and subsequently the failure rates for each group. In addition, the Mann-Whitney U test was used to investigate the relationship between revision and initial ACL graft size.

RESULTS

Out of the 711 out of 782 patients were included in this study. Only 42.6% of the patients did not need more than 4-strands to achieve an 8mm sized autograft. The patients who had autografts≤8mm in this study accounted for 17.1% of the population. About 7.2% of these patients required revision surgery. Patients with a 4-strand autograft size that was less than 8mm were 7.2 times more at risk for ACLR failure (RR=7.2, 95% CI: 6.02; 8.35, p=0.007).

CONCLUSIONS

There is a significant correlation between 4-strand autograft diameter size and the need for ACLR revision surgery.

LEVEL OF EVIDENCE

IV case series.

Age, activity level and meniscus injury, but not tear location, tibial slope or anterolateral ligament injury predict coping with anterior cruciate ligament injury

INTRODUCTION

Early recognition of potential predictors on the success of conservative treatment of anterior cruciate ligament (ACL) is important, as appropriate treatment can be applied to each individual patient. The goal of this study is to assess the patient demographic and radiological parameters that predict coping with ACL injuries.

METHODS

All patients presenting with a complete ACL injury between 2014 and 2018 at our clinic were included. The role of patient demographics (age, gender, activity level, meniscus injury and time from injury to clinic), and ACL tear location, bone bruises, tibial slope, and anterolateral ligament (ALL) injury were assessed on the success of conservative treatment using univariate and multivariate analyses.

RESULTS

Sixty-five patients (32%) were copers and 141 (68%) were non-copers. Univariate analysis showed that copers were significantly older (40 vs. 27 years, P < 0.001), had lower preinjury activity level (Tegner 5.7 vs. 6.5, P < 0.001) and less often lateral meniscus tears (16% vs. 5%, P = 0.019) but not medial meniscus tears (17% vs. 14%, P = 0.609) than non-copers. Multivariate analysis revealed that increasing age (P < 0.001), Tegner level ≤ 6 (P = 0.003) and no meniscus injury (P = 0.045) were independent predictors of coping with ACL deficiency.

CONCLUSIONS

Older age, participation in lower activity sports levels and absence of meniscus injury were predictive of coping with ACL deficiency, whereas there was no such role for tear location, tibial slope, lateral bone bruise presence, ALL injury or gender. These findings might help to identify potential copers and guide surgeons early in the optimal treatment for patients with ACL injury.

Posterior Tibial Slope in Patients Undergoing Anterior Cruciate Ligament Reconstruction With Patellar Tendon Autograft: Analysis of Subsequent ACL Graft Tear or Contralateral ACL Tear

BACKGROUND

Reports on greater posterior tibial slope (PTS) and its relationship to subsequent anterior cruciate ligament (ACL) injury show conflicting results; it has not been studied much in patients after ACL reconstruction with patellar tendon autograft (PTG).

HYPOTHESIS

Patients who suffered a subsequent ACL injury would have a larger PTS than patients who did not suffer a subsequent injury after primary or revision ACL reconstruction.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Patients received primary (n = 2439) or revision (n = 324) ACL reconstruction with PTG and were followed prospectively to determine the rate of graft tear and contralateral ACL tear. The PTS was measured preoperatively on digital lateral view radiographs. Intersecting lines were drawn along the medial tibial plateau and posterior tibia; the value of the acute angle at the lines' intersection was then subtracted from 90° to obtain the PTS. This procedure was completed by a clinical assistant with an intrarater reliability of 0.89. Chi-square analysis and t tests were used to determine the differences between rate of tears and measurements between groups. A threshold of PTS ≥10° was used for analysis.

RESULTS

The mean follow-up time was 11.6 ± 4.0 years. After primary surgery, the mean PTS in patients with graft tears was 5.4°± 3.1° versus 4.8°± 2.9° for patients without a tear (P = .041). The mean PTS was 4.9°± 3.4° for patients with contralateral tears (not statistically significantly different than the no-tear group; P = .80). Furthermore, patients with primary reconstruction with PTS ≥10° had a statistically significantly higher rate of graft tear (9.7%) than patients with PTS ≤9° (4.8%) (P = .003), but not a higher rate of contralateral tear. Among patients undergoing revision surgery, there were no statistically significant differences between the graft tear, contralateral tear, and no-tear groups with relation to PTS ≥10°.

CONCLUSION

After primary ACL reconstruction, patients with PTS >10° had a higher rate of subsequent graft tear but not a higher rate of contralateral tear. With revision surgery, there was no significant association between PTS and the rate of subsequent tear. Therefore, caution should be exercised when considering more radical interventions, such as osteotomy, to prevent retear in patients with high PTS.

Predictive Value of the Magnetic Resonance Imaging-Based Coronal Lateral Collateral Ligament Sign on Adolescent Anterior Cruciate Ligament Reconstruction Graft Failure

BACKGROUND

The coronal lateral collateral ligament (LCL) sign is the presence of the full length of the LCL visualized on a single coronal magnetic resonance imaging (MRI) slice at the posterolateral corner of the knee. The coronal LCL sign has been shown to be associated with elevated measures of anterior tibial translation and internal rotation in the setting of anterior cruciate ligament (ACL) tear.

HYPOTHESIS

The coronal LCL sign (with greater anterior translation, internal rotation, and posterior slope of the tibia) will indicate a greater risk for graft failure after ACL reconstructive surgery.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Retrospective review was performed of adolescent patients with ACL reconstruction: a cohort without graft failure and a cohort with graft failure. MRI was utilized to measure tibial translation and femorotibial rotation and to identify the coronal LCL sign. The posterior tibial slope was measured on lateral radiographs. Patient-reported outcomes were collected.

RESULTS

We identified 114 patients with no graft failure and 39 patients with graft failure who met all criteria, with a mean follow-up time of 3.5 years (range, 2-9.4 years). Anterior tibial translation was associated with anterolateral complex injury (P < .001) but not graft failure (P = .06). Internal tibial rotation was associated with anterolateral complex injury (P < .001) and graft failure (P = .042). Posterior tibial slope was associated with graft failure (P = .044). The coronal LCL sign was associated with anterolateral complex injury (P < .001) and graft failure (P = .013), with an odds ratio of 4.3 for graft failure (95% CI, 1.6-11.6; P = .003). Subjective patient-reported outcomes and return to previous level of sport were not associated with failure. Comparison of MRI before and after ACL reconstruction in the graft failure cohort demonstrated a reduced value in internal rotation (P = .003) but no change in coronal LCL sign (P = .922).

CONCLUSION

Our study demonstrates that tibial internal rotation and posterior slope are independent predictors of ACL graft failure in adolescents. Although the value of internal rotation could be improved with ACL reconstruction, the presence of the coronal LCL sign persisted over time and was predictive of graft rupture (without the need to make measurements or memorize values of significant risk). Together, these factors indicate that greater initial knee deformity after initial ACL tear predicts greater risk for future graft failure.

Posterior Tibial Slope Measurements Using the Anatomic Axis Are Significantly Increased Compared With Those That Use the Mechanical Axis

PURPOSE

To compare posterior tibial slope (PTS) measurements from standard lateral knee radiographs with measurements from full-length lateral tibia radiographs.

METHODS

We performed a multicenter, prospective study. Lateral knee and full-length lateral tibia radiographs were obtained for each patient, and PTS was measured. Slope measurements were obtained by measuring the angle between an average of the medial and lateral tibial plateaus and a representative tibial diaphysis line. The proximal anatomic axis was measured on lateral knee radiographs, and both the mechanical axis and anatomic axis were measured on full-length lateral tibia radiographs. The mechanical axis was defined as the center of the plateau to the center of the plafond, and the anatomic axis was defined as the center of the tibial diaphysis. The minimal clinically significant difference was defined a priori as 2° of PTS or greater.

RESULTS

A total of 140 patients met the inclusion criteria. The average PTS using the proximal anatomic axis was 11.6° ± 3.2° on lateral knee radiographs; the PTS measured on full-length lateral tibia radiographs was 9.5° ± 3.4° using the mechanical axis and 11.8° ± 3.1° using the anatomic axis. There was a significant difference between the measurements with the mechanical axis and both anatomic axis measurements (P < .01) but no significant difference between the 2 anatomic axis measurement techniques (P = .574). In total, 55% of patients (n = 77) had a 2° or greater difference between the proximal anatomic axis and mechanical axis PTS measurement techniques.

CONCLUSIONS

There was no significant difference between PTS measurements that used the proximal anatomic axis from lateral knee radiographs and those that used the anatomic axis from full-length lateral tibia radiographs. Thus, lateral knee radiographs are adequate to accurately obtain tibial slope measurements. However, there was a significant difference between PTS measurements that used the anatomic axis and those that used the mechanical axis of the tibia.

CLINICAL RELEVANCE

It is recommended that future studies report tibial slope based upon measurements that utilize the anatomic axis in order to ensure that subsequent conclusions are comparable, independent of the radiographic view.