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

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.

Combined All-Inside Anterior Cruciate Ligament Reconstruction and Tibial Anterior Closing Wedge Tibial Osteotomy Using Staple Fixation: Surgical Technique

Failure of anterior cruciate ligament (ACL) reconstruction may be associated with a number of technical, anatomic, and patient-related factors. In particular, increased posterior tibial slope is associated with a greater risk of failure after both primary and revision ACL reconstruction, likely a result of increased load across the ACL graft. Surgical treatment of increased posterior tibial slope most commonly involves an anterior closing-wedge osteotomy of the proximal tibia, which may be performed in a simultaneous or staged fashion with ACL reconstruction. The authors describe a technique for combined, single-stage, all-inside ACL reconstruction and anterior closing-wedge osteotomy using staple fixation. The proposed technique provides adequate fixation of the osteotomy while minimizing hardware interference with the ACL tunnel placement and maximizing proximal femoral bone stock.

Slope-Reducing Tibial Plateau-Leveling Osteotomy

Increased posterior tibial slope (PTS) is a risk factor for anterior cruciate ligament (ACL) tear and ACL reconstruction failure. Anterior closing-wedge osteotomy (ACWO) decreases the PTS and the risk of reinjury after revision ACL reconstruction. ACWO techniques include supratubercular, transtubercular, or infratubercular. However, there are limitations to the amount of slope correction an ACWO can achieve in the context of a massively abnormal slope. If the necessary slope correction is greater than 20°, a supratubercular ACWO cannot achieve the required correction without high risk of brittle fixation, a transtubercular ACWO would introduce increased morbidity of a secondary osteotomy and change the biomechanics of the patellofemoral joint resulting in significant patella alta, and an infratubercular ACWO would require a major anterior tibial metaphysodiaphyseal resection. The tibial plateau leveling osteotomy (TPLO) is an alternative curved osteotomy commonly used in canines that avoids the adverse events associated with a large ACWO. Further benefits of TPLO for massive slope correction include improved maintenance of native soft-tissue tension, avoidance of major recurvatum, and the ability to control the correct degree. We describe an open technique for a TPLO to decrease the PTS and the risk of recurrent ACL injury.

Infratuberositary slope-decreasing anterior closed wedge proximal tibial osteotomy is safe and shows rapid bone healing

PURPOSE

Different techniques of slope-decreasing anterior closed-wedge proximal tibial osteotomy (ACW-PTO) have been described. To determine the peri- and post-operative complication rate and obtain data on bone healing in ACW-PTO with an infratuberositary approach.

METHODS

A total of 170 consecutive ACW-PTO of two sports-orthopaedic centres were retrospectively evaluated (97 and 73, respectively). Routine follow-up was performed after 6 weeks and was available in 166 cases (97.7%). Medical charts and x-rays of these cases were reviewed with regard to technique-specific complications. Lateral x-rays (n = 155) at 6 weeks post-operatively were evaluated with regard to bone healing (completely healed, partially healed or with no or delayed signs of bone healing). A multivariate binary logistic regression was performed to detect factors that influence bone healing.

RESULTS

There was one case with haematoma and superficial wound-healing problems after 5 weeks with progression to a deep wound infection and revision surgery (plate exchange) at 11 weeks after the index surgery. One case with delayed bone healing was treated with plate exchange combined with revision anterior cruciate ligament reconstruction after 4 months. The further course of both cases was uneventful. No other complications were observed. Therefore, the overall complication rate was 1.2% (2 out of 166). Radiologic evaluation at 6 weeks showed complete healing in 104 cases (67.1%), partial healing in 50 cases (32.3%) and delayed healing only in the aforementioned case (0.6%), respectively. All cases of partial healing showed complete healing at 12 weeks. In regression analysis, a completely closed osteotomy (odds ratio [OR] = 3.5, p = 0.003) and compression of the osteotomy (OR = 2.5, p = 0.026) were significantly associated with complete bone healing at 6 weeks.

CONCLUSIONS

ACW-PTO using an infratuberositary approach is very safe with regard to complication rate and shows rapid bone healing. The osteotomy should be completely closed and compression should be applied for optimal bone healing.

STUDY DESIGN

Case series with pooled data of two centres.

LEVEL OF EVIDENCE

Level 4.

Anterior Cruciate Ligament Allograft Reconstruction in Females Can Produce Outcomes Comparable to Those of Autografts in Male Counterparts

There are unique anatomical and geometric risk factors that contribute to higher injury rates of the anterior cruciate ligament (ACL) in women. Allografts are an important alternative option for female patients.Patients who underwent primary ACL reconstruction were retrospectively evaluated. The case group comprised female patients with ACL allograft reconstruction, and the control group comprised male patients with ACL reconstruction. Functional and clinical evaluations were based on the pre- and postoperative Cybex test, Lysholm score, International Knee Documentation Committee subjective and objective measurement criteria, and Tegner Activity Scale questionnaires. Radiological comparisons were performed using the femorotibial angle (FTA), posterior tibial slope (PTS), and intercondylar notch width (INW). The roof inclination angle (RIA) was assessed using magnetic resonance imaging.The two groups (female [44] and male [88]) had an average follow-up period of 57.9 ± 19.3 months and average ages of 36.5 ± 10.9 and 35.2 ± 11.7 years, respectively. Functional and clinical outcomes showed no differences between the groups, except that the return to the preinjury activity level was higher in the female group (95% vs. 77%, p < 0.001). The female group showed larger FTA and PTS and smaller INW and RIA than those of the male group (p < 0.001, 0.008, <0.001, and 0.035, respectively).Female ACL allograft reconstruction showed comparable outcomes to those of their male counterparts, and the return to preinjury activity levels was significantly higher in women. However, women showed lower activity levels and were more vulnerable to geometric risk factors than their male counterparts.

Enhanced reliability and time efficiency of deep learning-based posterior tibial slope measurement over manual techniques

PURPOSE

Multifaceted factors contribute to inferior outcomes following anterior cruciate ligament (ACL) reconstruction surgery. A particular focus is placed on the posterior tibial slope (PTS). This study introduces the integration of machine learning and artificial intelligence (AI) for efficient measurements of tibial slopes on magnetic resonance imaging images as a promising solution. This advancement aims to enhance risk stratification, diagnostic insights, intervention prognosis and surgical planning for ACL injuries.

METHODS

Images and demographic information from 120 patients who underwent ACL reconstruction surgery were used for this study. An AI-driven model was developed to measure the posterior lateral tibial slope using the YOLOv8 algorithm. The accuracy of the lateral tibial slope, medial tibial slope and tibial longitudinal axis measurements was assessed, and the results reached high levels of reliability. This study employed machine learning and AI techniques to provide objective, consistent and efficient measurements of tibial slopes on MR images.

RESULTS

Three distinct models were developed to derive AI-based measurements. The study results revealed a substantial correlation between the measurements obtained from the AI models and those obtained by the orthopaedic surgeon across three parameters: lateral tibial slope, medial tibial slope and tibial longitudinal axis. Specifically, the Pearson correlation coefficients were 0.673, 0.850 and 0.839, respectively. The Spearman rank correlation coefficients were 0.736, 0.861 and 0.738, respectively. Additionally, the interclass correlation coefficients were 0.63, 0.84 and 0.84, respectively.

CONCLUSION

This study establishes that the deep learning-based method for measuring posterior tibial slopes strongly correlates with the evaluations of expert orthopaedic surgeons. The time efficiency and consistency of this technique suggest its utility in clinical practice, promising to enhance workflow, risk assessment and the customization of patient treatment plans.

LEVEL OF EVIDENCE

Level III, cross-sectional diagnostic study.

Cut-off value for the posterior tibial slope indicating the risk for retear of the anterior cruciate ligament

PURPOSE

The significance of the posterior tibial slope (PTS) has increasingly come into focus in anterior cruciate ligament (ACL) reconstruction being a risk factor for ACL graft failure. Nevertheless, inconsistent data on the critical value of the PTS exist. The purpose of this study was to define a cut-off value for the PTS in ACL surgery.

METHODS

In a retrospective cohort study, 350 revision ACL reconstructions (ACL-RR) with a failed ACL hamstring graft and 350 primary ACL reconstructions (ACL-R) were matched according to age, gender, concomitant injuries and graft characteristics and compared to a healthy control group. Using the proximal anatomic axis, lateral knee radiographs were evaluated for the PTS, interrater reliability was defined, ROC curves, Fischer's exact test and Baptista-Pike method were applied to define specificity and the odds ratio for a critical PTS value.

RESULTS

Radiographic evaluation proved excellent interrater reliability (intraclass correlation coefficient 0.969). Evaluation of the PTS revealed 10.0 ± 2.2 (5-15) degrees in the ACL-RR group, 7.8 ± 1.8 (4.2-13) degrees in the ACL-R group and 6.6 ± 1.9 (3.6-12) degrees in the control group with significant differences between the groups (p < 0.001). A PTS value of 10.1 degrees proved a specificity of 98% for the prediction of an ACL graft failure and indicated an 11-fold risk for a retear of the ACL.

CONCLUSION

A PTS exceeding 10.1 degrees carries an 11-fold risk for ACL graft failure and, therefore, should be considered in ACL reconstruction. These findings might serve as a cut-off value for the indication of a slope-reducing high tibial osteotomy in ACL surgery.

LEVEL OF EVIDENCE

Level III.

Sex specific considerations in anterior cruciate ligament injuries in the female athlete: State of the art

The increased participation of females in sports has been accompanied by an increase in the rate of anterior cruciate ligament (ACL) injuries. The literature has identified risk factors for noncontact ACL injuries in female athletes, including anatomic, hormonal, biomechanical, neuromuscular, and environmental factors. This review will provide an overview of sex-specific considerations when managing female athletes with ACL injuries. A discussion of sex-specific surgical and rehabilitative treatment strategies with the goal of optimizing return to sport after ACL reconstruction will be emphasized.

Preservation of the MMPH and Status of the Notch Configurations Are Important Factors for Successful Revision ACL Reconstruction

OBJECTIVE

The aim of this study was to identify the differences in anatomical factors between the patients who underwent revision and primary anterior cruciate ligament reconstructions (ACLR) and compare the outcomes between the 2 surgeries.

DESIGN

Retrospective cohort study.

SETTING

Single institution tertiary academic center between 2014 and 2020.

PATIENTS

A total of 84 matched patients who underwent revision (group I) or primary ACLR (group II).

INTERVENTIONS

Radiological evaluations were performed using side-to-side differences (SS-D), femorotibial angle, and posterior tibial slope. The medial meniscus posterior horn status as width (MMPHW), medial tibial plateau width (MTPW), notch configurations, tunnel positions, and sagittal graft angle were measured using 3D-CT and magnetic resonance imaging (MRI).

MAIN OUTCOME MEASURES

Graft signals were assessed using MRI. The clinical outcomes were assessed.

RESULTS

Group I showed larger SS-D and higher mean Howell grade of anterior cruciate ligament (ACL) graft than group II ( P = 0.002 and P = 0.004, respectively). Multivariate regression analyses showed that the decreased MMPHW/MTPW ratio ( P = 0.010) and notch width index ( P < 0.007) were significantly independent factors associated with the higher Howell grade of ACL grafts. The decreased MMPHW/MTPW ratio ( P < 0.001) was a significantly independent factor associated with larger SS-D. In the subgroup analysis, all patients in the notchplasty group showed wider notches postoperatively ( P < 0.001).

CONCLUSIONS

Revision ACLRs resulted in worse ACL signal intensity and stability outcome. The results of this study suggest that it may be important to preserve the MMPHW as much as possible and check notch configurations, especially during a revision ACLR.

Guided Growth for Correction of Elevated Tibial Posterior Slope in Pediatric ACL Deficiency: A Case Report

CASE

Fourteen-year-old boy, history of autism presented with bilateral knee instability. Imaging revealed bilateral anterior cruciate ligament (ACL) insufficiency, 20° of posterior tibial slope (PTS) on the right and 18° on the left. A guided growth technique using anterior placed tension band plates was used to correct the PTS. At 22 months, the PTS corrected to 5.5° on the right and 6° on the left. The patient's knee stability improved, and he resumed activities at 30 months.

CONCLUSION

Pediatric ACL insufficiency in the setting of elevated PTS can be successfully corrected with a guided growth technique.

Proximal tibial anatomical axis and anterior tibial cortex-based measurements of posterior tibial slope on lateral radiographs differ least from actual posterior tibial slope-A biomechanical study

Purpose

To compare different measurement techniques of the posterior tibial slope (PTS) on lateral radiographs with the actual in situ PTS and evaluate the effect of tibial malrotation and image section length.

Methods

Actual PTS was measured on eight fresh-frozen tibiae using a portable 6-axis measuring arm with an accuracy of ±0.01°. True lateral radiographs were taken in the neutral position and after applying 10/20/30° internal/external rotation (IR/ER) and 5/10/15° varus/valgus rotation. The PTS was measured radiographically using five different reference axes: anterior tibial cortex (ATC), anatomical tibial axis, proximal tibial anatomical axis (PTAA), posterior tibial cortex (PTC) and fibular shaft axis (FSA).

Results

The ATC and PTAA methods showed the lowest deviation from the actual PTS, while the PTC method showed the highest difference of 5.5 ± 1.5° (medial) and 7.1 ± 1.8° (lateral) among all tested methods (p < .001). The PTAA technique showed a 1.9 ± 1.4° (medial) and 2.9 ± 1.8° (lateral) difference from the actual slope (n.s.). ER caused the PTS to increase 0.7 ± 2.0° (10° ER, n.s.) to 3.4 ± 2.1° (30° ER, p < .05), whereas IR caused the PTS to decrease 1.6 ± 1.3° (n.s) to 4.1 ± 1.7° (p < .05) when comparing to the PTAA method for the neutral position. Varus and valgus rotation showed the highest deviation from the neutral rotation at 15° valgus (3.1 ± 2.1°, n.s.).

Conclusion

Tibial slope measurements have a high degree of variability between different measurement methods, while the ATC and PTAA methods showed the least deviation from the actual PTS measured in this in vitro model. Malrotation resulted in a severe distortion of the PTS values, which may alter preoperative planning and intraoperative results. Therefore, radiographic PTS measurements may be contrasted with more objective, reproducible and reliable measuring methods.

Level of Evidence

There is no level of evidence as this study was an experimental laboratory study.

Age under 20 years, pre-operative participation in pivoting sports, and steep posterior tibial slope of more than 12° are risk factors for graft failure after double-bundle anterior cruciate ligament reconstruction

Purpose

Younger age and steep posterior tibial slope (PTS) have been reported as risk factors for graft failure after anterior cruciate ligament reconstruction (ACLR). Few studies have evaluated these risk factors simultaneously in a large cohort of patients undergoing double-bundle ACLR (DB-ACLR). Therefore, this retrospective study aimed to simultaneously investigate known risk factors such as PTS and age in DB-ACLR, determine their thresholds and calculate odds ratios (ORs).

Methods

We investigated 482 knees that underwent DB-ACLR with a follow-up period of at least 2 years. Receiver operating characteristic analysis determined cut-off values for age and PTS for graft failure. Subsequently, logistic regression analysis was conducted to evaluate the effects of age, sex, height, weight, laterality, surgical waiting period, pre-operative sport type and level, meniscal injury, hyperextension, general joint laxity and PTS on graft failure.

Results

Graft failure was observed in 33 out of 482 knees (6.8%). Notably, the graft failure group was significantly younger (18.0 ± 5.0 years [standard deviation] vs. 30.4 ± 13.1 years, p < 0.01) and had a steeper PTS (11.9 ± 2.3° [standard deviation] vs. 9.6 ± 2.9°, p < 0.01) than the group with no graft failure. The cut-off values were 20.0 years for age (specificity, 64.6%; sensitivity, 87.9% and area under the curve, 0.808) and 12.0° for PTS (specificity, 70.9%; sensitivity, 69.7% and area under the curve, 0.734). Logistic regression analysis identified an age of <20 years (OR = 10.1; p < 0.01), PTS of ≥12° (OR = 5.6; p < 0.01) and pre-operative participation in pivoting sports (OR = 6.0; p < 0.01) as significant risk factors for graft failure.

Conclusion

We identified an age of <20 years, PTS of ≥12° and pre-operative participation in pivoting sports as significant risk factors for graft failure after DB-ACLR.

Level of Evidence

Level III.

Risk for Revision ACLR After Primary All-Inside Quadrupled Semitendinosus Hamstring Tendon Autograft ACLR With Independent Suture Tape Augmentation: A Retrospective Cohort Study

Background

The rate of failed anterior cruciate ligament reconstruction (ACLR) remains high in the younger and more active patient populations. Suture tape augmentation (STA) in addition to ACLR may reduce the risk for revision surgery.

Purpose/Hypothesis

The purpose of this study was to compare patient outcomes between patients who underwent primary all-inside quadrupled semitendinosus hamstring tendon autograft (QST-HTA) ACLR with and without STA. It was hypothesized that the STA cohort would demonstrate a lower incidence of subsequent revision ACLR while maintaining comparable patient-reported outcomes.

Study Design

Cohort study; Level of evidence, 3.

Methods

All patients ≤40 years of age who received primary all-inside QST-HTA ACLR with and without independent STA augmentation were identified. The following validated patient-reported outcome measures (PROMs) were collected: visual analog scale for pain, Single Assessment Numeric Evaluation, Knee injury and Osteoarthritis Outcome Score subscales, and Tegner activity scale. KT-1000 arthrometer measurements were collected pre- and postoperatively. Cox proportional hazards model and nominal logistic regression analysis were used to assess additional variables associated with revision ACLR.

Results

A total of 104 patients with a mean age of <22 years were included in the final data analysis (STA: 36 patients; control: 68 patients). Significantly fewer patients in the STA group sustained a graft failure necessitating revision surgery at the final follow-up (5.6% vs 24%; relative risk, 0.24 [95% CI, 0.06-0.97]; P = .017). Four-year graft survival was significantly higher in the STA group (97.2% vs 82.4%; P = .031). All PROMs significantly improved postoperatively except for Tegner levels, which decreased in both groups compared with their preinjury levels (P < .001). Return to sports was similar in both groups with >70% of patients returning to their previous level of competition. Regression analysis demonstrated increased risk for revision ACLR in younger patients, high school athletes, and those with higher postoperative activity levels.

Conclusion

QST-HTA ACLR with STA was associated with reduced risk for revision ACLR compared with nonaugmented QST-HTA ACLR in this young patient population. Furthermore, the addition of suture tape did not appear to affect postoperative patient-reported and return-to-sports outcomes.

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.

Posterior Tibial Slope Measurements of the Medial and Lateral Plateaus Vary Widely Between Magnetic Resonance Imaging and Computed Tomography

PURPOSE

To compare posterior tibial slope (PTS) measurements of the medial tibial plateau (MTP) and lateral tibial plateau (LTP) on magnetic resonance imaging (MRI) versus computed tomography (CT) to determine the agreement of measurement between imaging modalities.

METHODS

Patients aged 15 to 65 years with concurrent MRI and CT imaging were initially included. Knees with significant arthrosis (Kellgren-Lawrence grade >2), proximal tibia fracture, or artifact obscuring visualization were excluded. Two independent raters measured PTS of the MTP and LTP on paired MRI and CT. Inter- and intrarater reliability were assessed using the intraclass correlation coefficient (ICC). Intermethod agreement was assessed using ICC and Bland-Altman analyses. An acceptable Bland-Altman limit of agreement (LOA) was set at ±2°, requiring 95% of measurement differences between imaging modalities to fall between ±2° for an acceptable level of agreement.

RESULTS

Forty-six knees in 45 patients met final inclusion criteria. Inter-rater reliability was good for MRI (ICC 0.78-0.83) and moderate to good for CT (ICC 0.64-0.80) studies. Intrarater reliability was moderate to excellent (ICC 0.64-0.94). Intermethod agreement between MRI and CT was poor at the MTP (ICC 0.34-0.42) and moderate at the LTP (ICC 0.59-0.70). Bland-Altman analysis demonstrated high variability of PTS measurements between MRI and CT: 0.16° (95% LOA -6.10° to 6.41°) for MTP for Rater 1; 0.22° (95% LOA -5.01° to 5.45°) for LTP for rater 1; -0.95° (95% LOA -7.22° to 5.33°) for MTP for Rater 2; -0.99° (95% LOA -6.48° to 4.85°) for LTP for rater 2, with only 47.83% to 60.87% of measurement differences falling within the predetermined acceptable LOA of ±2°.

CONCLUSIONS

Although the inter- and intrarater reliability was moderate to excellent, the degree of agreement between PTS measurements on MRI and CT was highly variable at both medial and lateral plateaus. Although some variability may have been due to the study's limitations, PTS measurements at individual plateaus may not be interchangeable between MRI and CT.

LEVEL OF EVIDENCE

Level III, retrospective cohort study.

The influence of tibial length on radiographic posterior tibial slope measurement: How much tibia do we need?

PURPOSE

The purpose of this study was to determine whether significant differences exist when comparing posterior tibial slope (PTS) measured using increasing lengths of the tibia to determine the anatomical axis.

METHODS

Patients with full-length weight-bearing tibial radiographs were retrospectively identified from 2014 to 2022 at a single institution. Patients were excluded if there was any previous history of lower extremity fracture or osteotomy. The anatomical axis of the tibia was determined using the full length of tibial radiographs, and the "reference PTS" was measured using this axis. Using the same radiograph, the PTS was measured using four different anatomical axes at standardized tibial lengths. While the center of the proximal circle remained constant at 5-cm below the tibial plateau, the center of the distal circle was drawn at four points: a) overlapping circles; b) 10-cm distal to the tibial plateau; c) 15-cm distal to the tibial plateau; d) half the length of the tibia, measured from the tibial plateau to the tibial plafond. Bivariate correlation and frequency distribution analysis (measurements >2-degrees from reference PTS) were performed between the reference PTS and PTS measured at each of the four other lengths.

RESULTS

A total of 154 patients (39.8 ± 17.4 years old, 44.2% male) were included in the final analysis. Measurements at each of the four tibial lengths were all significantly different from the reference PTS (p < 0.001). The correlation strength improved with increasing tibial length (overlapping: R = 0.681, 10-cm: R = 0.821, 15-cm: R = 0.937, and half-tibia: R = 0.963). The number of PTS measurements >2-degree absolute difference from the reference PTS decreased with increasing tibial length (overlapping: 40.3%, 10-cm: 24.0%, 15-cm: 26.0%, and half-tibia: 18.8%).

CONCLUSION

Assessment of PTS is dependent on the length of the tibia utilized to obtain the anatomical axis. Accuracy and precision of PTS measurements improved with increasing length of tibia used to determine the anatomical axis.

STUDY DESIGN

Case series.

Around-the-knee osteotomies part 1: definitions, rationale and planning-state of the art

Knee osteotomies are essential orthopedic procedures with the ability to preserve the joint and correct ligament instabilities. Literature supports the correlation between lower limb malalignment and outcomes after knee ligament reconstruction and cartilage procedures. Concepts such as joint line obliquity, posterior tibial slope angle, and intra-articular deformity correction are integral components of both preoperative planning and postoperative evaluations. The concept of preserving and/or restoring joint line congruence during simultaneous correction of varus or valgus deformity can be achieved through several different approaches. With advancements in osteotomy research and surgical planning technology, the surgical decision-making has increased in complexity. Based upon a patient's specific deformity, decisions need to be made whether to perform a single-level (proximal tibia or distal femur) versus double-level (both proximal tibia and distal femur) osteotomy, and whether to correct deformity in a single plane (coronal or sagittal) or perform a biplanar osteotomy, correcting two of the malalignments in either coronal, sagittal, or axial planes. Osteotomy procedures prioritize safety, reproducibility, precision, and meticulous planning. Equally important is the proactive management of possible complications and the implementation of preventive strategies for complications such as hinge fractures and unintentional changes to alignment in other planes. This review navigates the intricate landscape of lower limb alignment, commencing with foundational definitions and rationale for performing osteotomies, progressing through the planning phase, and addressing the critical aspect of complication prevention, all while looking ahead to anticipate future advancements in this field. However, rotational osteotomies and tibial tubercle osteotomies in isolation or as an adjunct procedure are beyond the scope of this review.

Correlation between higher lateral tibial slope and inferior long term subjective outcomes following single bundle anterior cruciate ligament reconstruction

BACKGROUND

The impact of anatomical factors, such as the lateral tibial slope (LTS), on outcomes following anterior cruciate ligament (ACL) reconstruction is an area of growing interest. This study was led by the observation that patients with a higher LTS may have different recovery trajectories.

HYPOTHESIS/PURPOSE

The purpose of this study was to investigate the correlation between a higher LTS and long term subjective outcomes following single-bundle ACL reconstruction.

STUDY DESIGN

This study was designed as a retrospective cohort study.

METHODS

The study comprised 138 patients who underwent single-bundle ACL reconstruction. The LTS was measured on preoperative radiographs. Patient-reported outcome measures (PROMs) were collected, which included the Lysholm Knee Score, UCLA Activity Score, IKDC Score, and Tegner Activity Score, over a mean follow-up duration of 137 months.

RESULTS

A significant negative correlation was found between LTS and all measured PROMs (p < 0.001). The established cut-off value of LTS distinguishing between "Good" and "Fair" Lysholm scores was 8.35 degrees. Female patients have statistically significant higher LTS and lower PROMs scores than male. Patients with LTS greater than or equal to 8.35 had significantly lower PROMs, indicative of poorer functional and subjective outcomes.

CONCLUSION

Our findings suggest that a higher LTS is associated with inferior subjective outcomes following single-bundle ACL reconstruction in long term. The LTS cut-off value of 8.35 degrees could potentially be used as a reference in preoperative planning and patient counseling.

CLINICAL RELEVANCE

Understanding the relationship between LTS and ACL reconstruction outcomes could inform surgical planning and postoperative management. These findings highlight the need to consider anatomical variances, such as LTS, when assessing patient-specific risks and recovery expectations, contributing to the advancement of personalized care in sports medicine.

Anterior cruciate ligament zoobiquity: Can man's best friend tell us we are being too cautious with the implementation of osteotomy to correct posterior tibial slope

Anterior cruciate ligament (ACL) reconstruction (ACLR) is used to treat clinical instability post ACL rupture, however, there is a high rate of incomplete return to sport and rerupture. There is increasing interest in posterior tibial slope as an intrinsic risk factor for ACLR failure and persistent instability. Zoobiquity describes the collaboration between the human and veterinary professions in order to advance the scientific understanding of both fields. Given the cranial cruciate ligament (CCL) in dogs is synonymous with the anterior cruciate ligament in humans, functioning to control internal rotation and anterior translation, but osteotomies, rather than ligament reconstruction, are the mainstay of treatment for CCL rupture, this editorial sort to gain insights into this form of treatment from the veterinary world. Level of Evidence: Level V, evidence.

Finite element analysis of the effect of tibial osteotomy on the stress of polyethylene liner in total knee arthroplasty

AIM

To explore the effects of tibial osteotomy varus angle combined with posterior tibial slope (PTS) on the stress of polyethylene liner in total knee arthroplasty (TKA) by building finite element model (FEM).

METHODS

Established the FEM of standard TKA with tibial osteotomy varus angle 0° to 9° were established and divided into 10 groups. Next, each group was created 10 FEMs with 0° to 9° PTS separately. Calculated the stress on polyethylene liner in each group in Abaqus. Finally, the relevancy between tibial osteotomy angle and polyethylene liner stress was statistically analyzed using multiple regression analysis.

RESULTS

As the varus angle increased, the area of maximum stress gradually shifted medially on the polyethylene liner. As the PTS increases, the percentage of surface contact forces on the medial and lateral compartmental of the polyethylene liner gradually converge to the same. When the varus angle is between 0° and 3°, the maximum stress of the medial compartmental surfaces of polyethylene liner rises smoothly with the increase of the PTS. When the varus angle is between 4° and 9°, as the increase of the PTS, the maximum stress of polyethylene liner rises first and then falls, forming a trough at PTS 5° and then rises again. Compared to the PTS, the varus angle has a large effect on the maximum stress of the polyethylene liner (p < .001).

CONCLUSION

When the varus angle is 0° to 3°, PTS 0° is recommended, which will result in a more equalized stress distribution of the polyethylene liner in TKA.

Four to 6° Is the Target Posterior Tibial Slope After Tibial Deflection Osteotomy According to the Knee Static Anterior Tibial Translation

PURPOSE

To correlate changes in posterior tibial slope (PTS) with changes to static anterior tibial translation (SATT) with tibial deflexion osteotomy (TDO), in order to define a target postoperative tibial slope based on postoperative SATT.

METHODS

We reviewed a consecutive series of primary and revision anterior cruciate ligament reconstruction with TDO between 2011 and 2022. PTS and SATT were measured pre- and postoperatively directly from the radiographs by 2 independent reviewers. Regression analysis was performed to investigate the relationship of postoperative SATT with PTS, gender, graft type, and meniscal injury.

RESULTS

A total of 48 patients were included in this study. The mean (SD) decrease in PTS and SATT was 8.85° (3.03°; 12.5° to 3.59°, P < .01), and 7.93 mm (3.68; 5.37 to -2.55 mm, P < .01), respectively. Upon univariate analysis, the only factor influencing ΔSATT was ΔPTS. For each 1° of decreased slope, SATT was reduced by 0.46 mm. The mean (SD) PTS for a negative SATT was 2.81° (2.78°) compared to 5.09° (3.25°) for a SATT of 0 to 5mm (P < .01).

CONCLUSIONS

This study reports weightbearing SATT in association with PTS after TDO. The TDO successfully reduced the SATT, with the change in PTS the only significant predictor of postoperative SATT. Based on our results, our previously held target of 2° to 5° PTS overcorrected the SATT. Therefore, considering as a goal 0 to 5 mm of SATT, we suggest a new target of 4° to 6° PTS.

LEVEL OF EVIDENCE

Level IV, retrospective cohort study.

The increased lateral tibial slope may result in inferior long-term clinical outcome after DB-ACL reconstruction

PURPOSE

To determine if there is a correlation between lateral tibial slope and long-term clinical results in patients who underwent double-bundle ACL reconstruction.

METHODS

We retrospectively reviewed patients that received double-bundle ACL reconstruction at a single institution by a single surgeon from January 2011 to December 2014. All the magnetic resonance imaging were reviewed and lateral tibial slopes (LTS) were recorded by an experienced surgeon and rechecked by the other two authors of this study that specialized in orthopedic knee surgery. The relationship between PROMs measurement and lateral tibial slope were analyzed. The patients were then separated into two groups (LTS > 7.4° and < 7.4°) according to the previous study.

RESULTS

A total of 119 patients were enrolled in this study. All enrolled patients were followed for at least 8 years. The PROMS result were negatively correlated with the lateral tibial slope (p values all < 0.001). The patients with high lateral tibial slope had significantly lower PROMS values (Lysholm 94.26 ± 5.61 vs 80.15 ± 8.28, p = 0.013; IKDC 82.99 ± 4.55 vs 70.09 ± 7.15, p = 0.003; Tegner 9.32 ± 0.95 vs 6.85 ± 1.99, p < 0.001). Finally, the LTS cutoff value between patients with "Good" and "Fair" Lysholm score in our study was 7.55 degrees.

CONCLUSIONS

Patients with high lateral tibial slope may result in inferior long-term subjective outcomes. The using of double-bundle ACL reconstruction along cannot overcome the negative impact caused by steep lateral tibial slope. A lateral tibial slope of 7.55° may be used as a cut-off for a good clinical outcome.

LEVEL OF EVIDENCE

III retrospective comparative prognostic trial.

Editorial Commentary: Don't Neglect the Medial Side of the Knee in Patients With Anterior Cruciate Ligament Injury

The medial collateral ligament (MCL) of the knee, as well as the posteromedial complex (including the posterior oblique ligament [POL] and ramp lesions of the meniscus) is often considered the "neglected" ligament or corner because of the belief that these anatomic structures have enormous regenerative potential and therefore hardly ever need surgical treatment. In patients with anterior ligament cruciate (ACL) tears, the overall combined prevalence of MCL (superficial [sMCL] and deep [dMCL]) and isolated dMCL injuries is high (16.5% + 24.8% = 41.3%). In terms of the POL, with a restraint to both internal tibial rotation and valgus rotation during extension, I have some doubts regarding its role in anteromedial instability (AMRI). In fact, AMRI of the knee is caused mainly by injury to both the ACL and the MCLs, resulting in coupled anterior tibial translation and external rotation, causing the medial tibial plateau to subluxate anteriorly. The sMCL provides the most substantial restraint, and the dMCL and POL play more minor roles. Finally, in ACL-deficient knees, ramp lesions are prevalent (9.3%-24.0%), and failing to identify and treat these lesions results in knee instability. In my experience, all unstable ramp lesions should be repaired. In ACL-deficient knees in patients with a tibial slope >5°, an occult ramp lesion should be strongly suspected. In summary, the medial compartment of the knee is complex and encompasses many structures (MCL, POL, ramp, tibial slope), and I believe that we will increasingly move toward individualized treatment.

A non-weight bearing protocol after ACL reconstruction improves static anterior tibial translation in patients with elevated slope and increased weight bearing tibial anterior translation

PURPOSE

Aim of this study is to evaluate the impact of a non-weight bearing (NWB) protocol within 21 post-operative days after anterior cruciate ligament (ACL) reconstruction on static and dynamic anterior tibial translations (SATT and DATT, respectively). The hypothesis is that delayed WB would improve ATT at 9 months follow-up.

METHODS

A series of patients treated with ACL reconstruction was retrospectively reviewed, comparing a group with immediate post-operative weight bearing (WB group) and a group without post-operative weight bearing (NWB group). The NWB protocol was applied to patients with posterior tibial slope (PTS) ≥ 12°, pre-operative SATT ≥ 5 mm, and/or meniscal lesions of root or radial type. SATT, and PTS were measured on 20° flexion monopodal lateral x-rays, while DATT on Telos™ x-rays at pre-operative and 9-months follow-up.

RESULTS

One hundred seventy-nine patients were included (50 NWB group, 129 WB group). The SATT worsened in the WB group with a mean increase of 0.7 mm (SD 3.1 mm), while in the NWB group, the SATT improved with a mean decrease of 1.4 mm (SD 3.1 mm) from the pre-operative to 9 months' follow-up (p < 0.001). The side-to-side Telos™ evaluation showed a significant improvement in DATT within both the groups (p < 0.001), but there was no difference between the two groups (p = 0.99).

CONCLUSION

The post-operative protocol of 21 days without WB led to an improvement in SATT at 9 months without an influence on DATT, and it is recommended for patients with a SATT ≥ 5 mm and/or a PTS ≥ 12° as part of an "à la carte" approach to ACL reconstruction.

LEVEL OF EVIDENCE

Level IV, Retrospective case series.

Extra-articular location of the three-dimensional mechanical axis in advanced knee osteoarthritis: an upright computed tomography study

PURPOSE

One of the most widely used benchmarks of lower-limb alignment is the mechanical axis (MA), which passes through the centers of the femoral head and the ankle in the weight-bearing position. However, where the MA passes through three-dimensionally (3D) is unclear. We investigated the MA in 3D (3D-MA) in knee osteoarthritis (OA) using upright computed tomography (CT).

MATERIALS AND METHODS

This study included 66 varus OA knees from 38 patients [age 70.0 (64.8-77.0) years; median (interquartile range)]. The 3D-MA was determined using upright CT data and compared among Kellgren-Lawrence (KL) grades. Further, correlations between the 3D-MA and other parameters were evaluated.

RESULTS

The 3D-MA was located at 5.3 (1.3-14.4)% medially and 7.1 (0.7-15.3)% posteriorly on the tibial plateau in KL-1, and was translated medioposteriorly with increased KL grade. The 3D-MA in KL-3 [30.6 (22.6-42.6)% medially and 50.9 (45.8-80.2)% posteriorly] and KL-4 [56.7 (48.5-62.9)% medially and 92.3 (50.2-127.1)% posteriorly] was located extra-articularly. The mediolateral position of the 3D-MA correlated with the femorotibial angle [correlation coefficient (CC) = - 0.85, p < 0.001], and the anteroposterior position of the 3D-MA correlated with the knee flexion angle (CC = - 0.93, p < 0.001).

CONCLUSION

Our analysis demonstrated that the 3D-MA in low-grade OA knees passes slightly medial and posterior to the knee center, and the 3D-MA is translated medioposteriorly with the progression of knee OA. Further, the 3D-MA is translated medially with varus progression and posteriorly with the progression of knee flexion contracture.

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.

Management of Bone Loss and Tunnel Widening in Revision ACL Reconstruction

➤ Both mechanical and biological factors can contribute to bone loss and tunnel widening following primary anterior cruciate ligament (ACL) reconstruction.➤ Revision ACL surgery success is dependent on graft position, fixation, and biological incorporation.➤ Both 1-stage and 2-stage revision ACL reconstructions can be successful in correctly indicated patients.➤ Potential future solutions may involve the incorporation of biological agents to enhance revision ACL surgery, including the use of bone marrow aspirate concentrate, platelet-rich plasma, and bone morphogenetic protein-2.

Effect of Anterior Tibial Closing Wedge Osteotomy on Coronal Tibial Alignment in Relation to Preoperative Medial Proximal Tibial Angle and Wedge Height

BACKGROUND

The posterior tibial slope has been identified as an anatomic risk factor for anterior cruciate ligament insufficiency and reruptures after anterior cruciate ligament reconstruction. Anterior tibial closing wedge osteotomy for correction of sagittal plane deformities has the potential to cause an unintended change in coronal plane alignment.

PURPOSE

To evaluate the effects of anterior tibial closing wedge osteotomies for correction of posterior tibial slope on coronal plane alignment using an infratuberosity surgical approach and to identify predictive factors for a change in medial proximal tibial angle (MPTA).

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

This study reports on retrospectively obtained data from radiographic measurements of 38 anterior tibial closing wedge osteotomies. All patients underwent revision anterior cruciate ligament reconstruction and had undergone ≥1 previous anterior cruciate ligament reconstruction. In all patients, an infratuberosity approach was used with angular stable plate fixation. Pre- and postoperative radiographs were examined retrospectively to detect changes in the sagittal and coronal plane alignment (posterior tibial slope and MPTA). A multivariate regression analysis was used to identify predictors for a change in MPTA.

RESULTS

The study group consisted of 14 women and 24 men whose mean ± SD age at the index procedure was 31.6 ± 8.7 years (range, 17-51 years). Posterior tibial slope decreased significantly (by 7.2° ± 2.3°; P < .001) from 14.6° ± 2.0° preoperatively to 7.4° ± 2.1° postoperatively. MPTA decreased significantly by 1.3° ± 1.5° (P = .005) from pre- to postoperative measurement. Mean wedge height was 9.3 ± 1.1 mm. A lower preoperative MPTA (coefficient = 0.32; P = .017; 95% CI, 0.06-0.59) and larger wedge height (coefficient = 0.48; P = .029; 95% CI, 0.05-0.9) were significant predictive factors for a decrease in MPTA.

CONCLUSION

Anterior tibial closing wedge osteotomy for posterior tibial slope reduction resulted in a slight but significant decrease of the MPTA in the coronal plane. These changes were dependent on the preoperative MPTA and the wedge height.

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.

Posterior tibial slope, notch width index and tibial tubercle to trochlear groove distance contribute to development of mucoid degeneration of the anterior cruciate ligament: a systematic review

PURPOSE

To determine what knee morphological factors are associated with the development of mucoid degeneration of the anterior cruciate ligament (ACL).

METHODS

Three databases MEDLINE, PubMed and EMBASE were searched from inception to January 29th, 2023 for literature outlining knee morphological factors that potentially lead to the development of mucoid degeneration of the ACL. The authors adhered to the PRISMA and R-AMSTAR guidelines as well as the Cochrane Handbook for Systematic Reviews of Interventions. Data on receiver operating characteristic (ROC) curve parameters such as area under the curve (AUC), sensitivity and specificity, odds ratios, as well as p values for comparisons of values between mucoid degeneration of the ACL and control patients were recorded. The Methodological Index for Non-Randomized Studies (MINORS) score was used for all studies to perform a quality assessment of included studies.

RESULTS

A total of 7 studies comprising 1326 patients (1330 knees) were included in this review. Four studies reported a significant association between increasing posterior tibial slope angles and mucoid degeneration of the ACL presence, with one study specifying that posterolateral tibial slope had a greater association than posteromedial tibial slope. Two studies reported a significant association between lower notch width index values and mucoid degeneration of the ACL presence. One study found that the presence of trochlear dysplasia was correlated with mucoid degeneration of the ACL and two studies found that increased tibial tuberosity-trochlear groove distance (TT-TG) was associated with mucoid degeneration of the ACL.

CONCLUSION

Increased posterior tibial slope, decreased notch width index, and elevated TT-TG and trochlear dysplasia were associated with the presence of mucoid degeneration of the ACL. Information from this review can aid surgeons in understanding what morphological features predispose their patients to the development of mucoid degeneration of the ACL. Identifying what features predispose patients to mucoid degeneration of the ACL can help determine if regular screening or preventative strategies are necessary.

LEVEL OF EVIDENCE

Level III.

Evaluation of the short-term outcomes of anatomic ACL reconstruction with hamstring autograft in patients with generalized joint laxity: A retrospective case-control study

PURPOSE

The outcomes of anterior cruciate ligament reconstruction (ACLR) in patients with generalized joint laxity (GJL) are not clearly understood. In this study, we compared the outcomes of ACLR with quadruple hamstring autograft between GJL and non-GJL patients.

METHODS

In a retrospective case-control study, 36 patients with GJL, according to the Beighton and Horan Joint Mobility Index, who underwent ACLR surgery, were included. Forty-four group-matched non-GJL patients were included in the control group. The mean follow-up of the patients was 20.65 ± 6.93‏ months. The outcomes of ACLR were evaluated by the Lachman test, pivot shift test, anterior tibial translation and KT-1000 side-to-side difference, and International Knee Documentation Committee (IKDC) scale.

RESULTS

The results of the Lachman and pivot shift test were not significantly different between the GJL and non-GJL patients (P = 0.67 and P = 0.27, respectively). The mean anterior tibial translation was 7.06 ± 1.41 mm in the GJL group and 6.11 ± 1.53 mm in the non-GJL group (P = 0.006). The mean KT-1000 side-to-side difference was 2.25 ± 1.31 mm in the case and 2.5 ± 1.44 mm in the control group (P = 0.42). The mean IKDC score of the patients was not significantly different between the GJL and non-GJL groups (66.1 ± 20.6 vs. 69.9 ± 16.1, P = 0.35). ACLR failure occurred in 2 (5.5%) patients of the GJL group and no patients of the control group (P = 0.21).

CONCLUSION

The present findings suggest ACLR with quadruple hamstring autograft as an adequate treatment for GJL patients, at least in short-term follow-up.

Considerations of the Posterior Tibial Slope in Anterior Cruciate Ligament Reconstruction: a Scoping Review

PURPOSE OF REVIEW

The significance of posterior tibial slope (PTS) in the setting of anterior cruciate ligament (ACL) injury and reconstruction has been increasingly recognized in recent years. The purpose of this article is to review the biomechanical and clinical studies of PTS in conjunction with ACL injuries, providing an evidence-based approach for the evaluation and management of this patient population.

RECENT FINDINGS

Several biomechanical and clinical studies suggest that PTS > 12° may be considered with increased strain on the native ACL fibers (or reconstructed graft) and greater anterior tibial translation, predisposing patients to a recurrent ACL injury. The increased rates of ACL injury and graft failure seen in those with increased PTS have garnered attention to diagnose and surgically address increased PTS in the revision ACL setting; however, the role of a slope-reducing high tibial osteotomy (HTO) in primary ACL reconstruction (ACL-R) has yet to be defined. Various HTO techniques to decrease PTS during revision ACL-R have demonstrated promising outcomes, though conclusions are limited by the multifactorial nature of revision surgery and concomitant procedures performed. Recent evidence suggests that increased PTS is a risk factor for failure following ACL-R, which may be mitigated by a slope-reducing HTO. Further investigation is needed to elucidate abnormal PTS values and to determine appropriate indications for a slope-reducing HTO in primary ACL-R.