Relationship of ACL Injury and Posterior Tibial Slope With Patient Age, Sex, and Race

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.

Do age, gender, and region affect tibial slope? A multi-center study

INTRODUCTION

Tibial slope is a parameter that is important to recognize in knee kinematics and knee surgery. A very wide range of values governing posterior tibial slope exist in the literature. This study is based on the hypothesis that age, gender and region may have an effect on the tibial slope.

MATERIALS AND METHODS

A total of 1800 lateral knee radiographies from five different countries [Turkey, Germany, Italy, Spain, and the United Kingdom (UK)] were utilized to measure the native posterior tibial slope. Participants were categorized in deciles with each decade of age after 40 years determined as a separate age group. Accordingly, four different age categories were formed in total, namely, the 40- to 49-, 50- to 59-, 60-69, and 70- to 79-year-old groups. Patients with severe knee osteoarthritis, those with a history of arthroscopic and open surgery around the knee, and those with severe morbid obesity and those outside the specified age group were excluded from the study. The angle between the line tangential to the medial tibial plateau and the proximal anatomical axis of the tibia was measured.

RESULTS

The tibial slope values of both males and females in the Turkish population were found to be higher than those in other populations. It was observed that tibial slope values increased with age in females in all populations, except for those in the Spanish and UK populations. In the male population, it was found that tibial slope values increased with age in all populations except in the Spanish population.

CONCLUSIONS

Region, age, and gender affect tibial slope in different populations in various ways. Our study shows that the region an individual lives in and living conditions affect the tibial slope.

Association Between Posterior Tibial Slope and Clinical Outcomes After Isolated Anterior Cruciate Ligament Reconstructions

Background Increased posterior tibial slope (PTS) is an important risk factor for non-traumatic graft failure and revision surgery after anterior cruciate ligament reconstruction. If a tibial posterior slope is an important factor for graft failure after anterior cruciate ligament reconstruction, does it affect clinical outcomes? This study aimed to evaluate the association between PTS and clinical outcomes after anterior cruciate ligament reconstruction. Material and methods Patients undergoing arthroscopic anterior cruciate ligament reconstruction with hamstring tendons in the clinic were evaluated retrospectively. Inclusion criteria were: patients with at least an 18-month follow-up period who were evaluated with the Tegner Lysholm scoring system, aged between 18 and 40 years, with only an anterior cruciate ligament rupture. PTSs were measured from the lateral radiographs of the knees. The patients were divided into two groups with a PTS of 10° or less. Results The mean Tegner Lysholm score was 86.8 ± 8.9. The mean PTS was 9.7° ± 1.5°. In total, 14 and 15 patients had a PTS of above 10° and below 10°, respectively. The mean age and follow-up time of patients were 28.5 ± 5.3 years and 24.6 ± 7.2 months in the group with a PTS of above 10° and 30.2 ± 5.3 years and 24.2 ± 5.18 months in the group with a PTS of below 10°, respectively. Tegner Lysholm scores were 88.2 ± 8.8 and 85.6 ± 9.1 in the group with values above 10° and below 10°, respectively. Statistically, there was no significant difference between the clinical outcomes of both groups. Conclusion PTS does not affect the clinical outcomes of patients who underwent arthroscopic anterior cruciate ligament reconstruction in the early period.

First revision ACL reconstruction combined with tibial deflexion osteotomy improves clinical scores at 2 to 7 years follow-up

PURPOSE

To report outcomes of first revision anterior cruciate ligament reconstruction (ACLR) with tibial deflexion osteotomy (TDO) in patients with posterior tibial slope (PTS) >10° at >2 years.

METHODS

The authors studied outcomes of a consecutive series of 16 patients that underwent first revision ACLR with TDO, including Lysholm score, IKDC subjective and objective scores, Lachman test, PTS, and signs of osteoarthritis. One woman was excluded because of early signs of knee arthritis, as the first revision ACLR took place 27 years following the primary ACLR. This left a final cohort of 15 patients assessed at minimum follow-up of 2 years.

RESULTS

The final cohort comprised 14 men and 1 woman aged 25.3 ± 6.6 years (range 16-39) at first revision ACLR. At final follow-up of 4.4 ± 1.5 years (range, 2-7), PTS was corrected from 12.5 ± 1.8° (range 8-15°) to 1.9 ± 3.6° (range - 4 to 8°), and none of the knees had radiographic signs of osteoarthritis. Lysholm score was 83.8±12.5, IKDC subjective score was 80.3±16.2, and IKDC objective score was A in 5 (33%), and B in 10 (67%). The net improvement exceeded the minimal clinically important difference (MCID) in 93% of patients for the IKDC subjective score and in 80% of patients for the Lysholm score. None of the knees had any retears, and only one required a reoperation to re-suture a medial meniscal tear due to trauma.

CONCLUSION

At 2-7 years following revision ACLR combined with TDO, net improvement exceeded the MCID in 93% of patients for IKDC subjective score and in 80% of patients for Lysholm score, with no retears or major complications. These results suggest that TDO is a safe technique to protect the ACL graft and might be considered as of first revision ACLR to correct excessive PTS.

LEVEL OF EVIDENCE

Level IV.

A posterior tibial slope angle over 12 degrees is critical to epiphyseal fracture of the proximal tibia: Three-dimensional finite element analysis

Introduction

The effects of the proximal tibial slope angle on the proximal tibial epiphysis remain unknown. To elucidate those effects, we investigated the strain distribution in proximal tibial epiphysis with different proximal tibial slope angles and proximal tibial epiphysis closure periods using finite element analysis.

Materials and methods

The finite element models of the proximal tibia were reconstructed from CT images and consisted of cancellous/cortical bone and epiphyseal plate. The variations in proximal tibial slope angle (range: 6-16°) and four closure variations in proximal tibial epiphysis (open, semi-open, semi-closed, and closed) were prepared. The loading force on the medial and lateral joint surface, and the tensile force by the patellar tendon were applied to the models, and the distal area of the tibia was fixed. The ratio of the equivalent strain in semi-open/semi-closed proximal tibial epiphysis to the strain in open proximal tibial epiphysis on different proximal tibial slope angles were calculated.

Results

The strain ratio between the semi-open/semi-closed and open proximal tibial epiphysis models indicated significant differences between 6 or 8° of proximal tibial slope angle and 12, 14, and 16° of proximal tibial slope angle models. In the increased proximal tibial slope angle model, a hoop-shaped strain in the closing proximal tibial epiphysis was found, and the maximum strain was found in the tibial tubercle.

Discussion

During epiphyseal closure, adolescents with an increased proximal tibial slope angle over 12° are significantly at risk for suffering from proximal tibial epiphyseal fractures compared with those under 10°.

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.

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.

Relationship Between Lateral Tibial Posterior Slope and Tibiofemoral Kinematics During Simulated Jump Landings in Male Cadaveric Knees

Background

It is not known mechanistically whether a steeper lateral posterior tibial slope (LTS) leads to an increase in anterior tibial translation (ATT) as well as internal tibial rotation (ITR) during a given jump landing.

Hypothesis

A steeper LTS will result in increased ATT and ITR during simulated jump landings when applying knee compression, flexion, and internal tibial torque of increasing severity.

Study Design

Descriptive laboratory study.

Methods

Seven pairs of cadaveric knees were harvested from young male adult donors (mean ± SD; age, 25.71 ± 5.53 years; weight, 71.51 ± 4.81 kg). The LTS of each knee was measured by a blinded observer from 3-T magnetic resonance images. Two sets of 25 impact trials of ∼700 N (1× body weight [BW] ±10%) followed by 2 sets of 25 trials of 1400 N (2× BW ±10%) were applied to a randomly selected knee of each pair. Similarly, on the contralateral knee, 2 sets of 25 impact trials of ∼1800 N (2.5× BW ±10%) followed by 2 sets of 25 trials of ∼2100 N (3× BW ±10%) were applied. Three-dimensional knee kinematics, including ATT and ITR, were measured at 400 Hz using optoelectronic motion capture. Two-factor linear mixed effect models were used to determine the relationship of LTS to ATT and ITR as impact loading increased.

Results

As LTS increased, so did ATT and ITR during increasingly severe landings. LTS had an increasing effect on ATT (coefficient, 0.50; 95% CI, 0.29-0.71) relative to impact force (coefficient, 0.52; 95% CI, 0.50-0.53). ITR was proportional to LTS (coefficient, 1.36; 95% CI, 0.80-1.93) under increasing impact force (coefficient, 0.49; 95% CI, 0.47-0.52). For steeper LTS, the increase in ITR was proportionally greater than the increase in ATT.

Conclusion

In male knee specimens, a steeper LTS significantly increased ATT and ITR during jump landings.

Clinical Relevance

Increases in ITR and ATT during jump landings lead to increased strain on the anterior cruciate ligament and are therefore associated with greater risk of ligament failure.

Effect of Posterior Tibial Slopes on Graft Survival Rates at 10 Years After Primary Single-Bundle Posterior Cruciate Ligament Reconstruction

BACKGROUND

Recent biomechanical studies have reported that stress on the posterior cruciate ligament (PCL) graft increases as the posterior tibial slope (PTS) decreases (flattened) in knees with single-bundle (SB) and double-bundle PCL reconstruction. Clinical studies of SB PCL reconstruction have shown that a flattened PTS is associated with a lesser reduction in posterior tibial translation. There is no long-term study on the clinical outcomes and graft survival rates of SB PCL reconstruction based on the medial and lateral PTSs measured on magnetic resonance imaging.

HYPOTHESIS

Flattened medial and lateral PTSs are associated with poor clinical outcomes and graft survival rates at a minimum 10-year follow-up after SB PCL reconstruction.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

In this cohort study, we retrospectively reviewed 46 patients (mean age, 28.8 ± 9.9 years) who underwent primary SB PCL reconstruction between 2000 and 2009. They were followed up for a minimum of 10 years. The medial and lateral PTSs were measured on preoperative magnetic resonance imaging. As a previous study reported that a steeper medial or lateral PTS showed a higher risk of anterior tibial translation at thresholds of 5.6° and 3.8°, respectively, the patients were divided into 2 groups based on the cutoff values of both the medial (≤5.6° vs >5.6°) and lateral (≤3.8° vs >3.8°) PTSs. Clinical scores (International Knee Documentation Committee subjective score, Lysholm score, and Tegner activity score), radiological outcomes (side-to-side difference [SSD] on stress radiography and osteoarthritis progression), and graft survival rates were compared between the groups at the last follow-up.

RESULTS

All clinical scores and the progression of osteoarthritis demonstrated no significant difference between the 2 subgroups of both the medial and lateral PTS groups. The mean SSD on stress radiography after SB PCL reconstruction was significantly greater in patients with a medial PTS ≤5.6° than in patients with a medial PTS >5.6° (8.4 ± 3.9 vs 5.1 ± 2.9 mm, respectively; P = .030), while the lateral PTS subgroups after SB PCL reconstruction demonstrated no significant difference. The minimum 10-year graft survival rate was significantly lower in patients with a medial PTS ≤5.6° (68.4% vs 92.6%, respectively; P = .029) and a lateral PTS ≤3.8° (50.0% vs 91.7%, respectively; P = .001).

CONCLUSION

A flattened medial PTS (≤5.6°) was associated with an increased SSD on stress radiography, and both flattened medial (≤5.6°) and lateral (≤3.8°) PTSs resulted in lower graft survival rates at a minimum 10-year follow-up after primary SB PCL 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.

Loading mechanisms of the anterior cruciate ligament

This review identifies the three-dimensional knee loads that have the highest risk of injuring the anterior cruciate ligament (ACL) in the athlete. It is the combination of the muscular resistance to a large knee flexion moment, an external reaction force generating knee compression, an internal tibial torque, and a knee abduction moment during a single-leg athletic manoeuvre such as landing from a jump, abruptly changing direction, or rapidly decelerating that results in the greatest ACL loads. While there is consensus that an anterior tibial shear force is the primary ACL loading mechanism, controversy exists regarding the secondary order of importance of transverse-plane and frontal-plane loading in ACL injury scenarios. Large knee compression forces combined with a posteriorly and inferiorly sloped tibial plateau, especially the lateral plateau-an important ACL injury risk factor-causes anterior tibial translation and internal tibial rotation, which increases ACL loading. Furthermore, while the ACL can fail under a single supramaximal loading cycle, recent evidence shows that it can also fail following repeated submaximal loading cycles due to microdamage accumulating in the ligament with each cycle. This challenges the existing dogma that non-contact ACL injuries are predominantly due to a single manoeuvre that catastrophically overloads the ACL.

Narrow Notch Width and Low Anterior Cruciate Ligament Volume Are Risk Factors for Anterior Cruciate Ligament Injury: A Magnetic Resonance Imaging-Based Study

BACKGROUND

The relationship between anterior cruciate ligament (ACL) injury and anatomical structures is still a topic of debate.

PURPOSE

The aim of this study was to compare knee geometry in demographically matched ACL-injured and ACL-intact athletes.

METHODS

We conducted a case-control study comparing 2 groups, each consisting of 55 professional athletes (44 men and 11 women): 1 group with complete ACL tears (cases) and 1 group with intact ACLs (controls). The groups were compared using magnetic resonance imaging (MRI) in terms of intercondylar notch geometry, tibial plateau characteristics, and ACL volume.

RESULTS

Among cases and controls, we found the cases had lower notch width (20.24 ± 2.68 mm vs. 22.04 ± 2.56 mm, respectively) and notch width index (0.29 ± 0.03 vs. 0.31 ± 0.03, respectively). The mean ACL volume in the cases (1181.63 mm³ ± 326 mm³) was also lower than in controls (1352.61 mm³ ± 279.84 mm³). The parameters of tibial slope geometry were comparable between groups. In addition, women had lower ACL volume than men (1254 ± 310 mm³ vs. 890 ± 267 mm³, respectively) and higher medial posterior tibial slope (4.76 ± 2.6 vs. 6.63 ± 1.83, respectively). Among cases, women had narrower notch width than men (16.9 ± 2.42 mm vs. 21.08 ± 2.03 mm). However, notch width index was comparable between male (0.3 ± 0.02) and female (0.28 ± 0.03) cases.

CONCLUSION

Our findings suggest that narrow notch width and low ACL volume may enhance the risk of ACL injury among athletes. There was no association found between posterior tibial slope and ACL injury between athletes with injured ACLs and controls. Further study is indicated.

Correlation of tibial parameters like medial, lateral posterior tibial slope and medial plateau depth with ACL injuries: randomized control study

BACKGROUND

This study aims to compare variables such as medial posterior tibial slope, lateral posterior tibial slope, medial tibial plateau depth calculated by preoperative MRI, and posterior tibial slope calculated by lateral knee X-ray on randomly selected patients with ACL injuries to a control group of patients without the injury. The secondary aim is to determine the critical value of these parameters and ascertain whether they can be used as a screening tool to identify at-risk individuals.

METHODS

Study participants included 426 subjects with noncontact knee injuries. Using stratified systematic random sampling, they were randomly divided into two equal groups of sixty, one for patients with ACL tears, and the other for those with ACL that was intact based on clinical and MRI findings. Based on the blinded assessment, MPTS, LPTS, MTPD, and PTS were assessed in MRI and lateral knee X-ray (PTS only), and the results were compared between groups using appropriate statistical models.

RESULTS

There were higher MPTS, LPTS, and PTS scores in the ACL tear group when compared to the control group (p < 0.01), while MTPD was lower when compared to the control group (p > 0.05). ROC analysis for predicting ACL tear revealed an area under the curve for MPTS, LPTS, PTS, and MTPD as 0.942, 0.907, 0.967, and 0.878, respectively. The critical angle for MPTS, LTPS, PTS and MTPD was 8.25°,6.75°,8.5° and 2.25 mm, respectively, which has sensitivity of 91.0%, 86.7%, 93.3% and 80%; specificity of 86.7%, 78.3%, 90.0% and 71.7%, respectively.

CONCLUSIONS

Medial posterior tibial slope, lateral posterior tibial slope, and posterior tibial slope were significantly higher in individuals in the ACL tear group but there was no significant difference in medial tibial plateau depth. MPTS, LPTS, and PTS are better predictors of identifying at-risk individuals predisposed to ACL injury than MTPD.

Anterior Slope Correction-Flexion Osteotomy in Traumatic Genu Recurvatum

A decreased posterior tibial slope has been associated with an increased risk of posterior cruciate ligament failure, anterior knee pain, and premature knee osteoarthritis. Trauma is a common cause of osseous genu recurvatum. Surgical management is recommended to correct the tibial slope and prevent knee pain and osteoarthritis progression. This article discusses our preferred treatment using a proximal tibial opening-wedge osteotomy for surgical management of genu recurvatum secondary to significant anterior tibial slope.

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.

Disparities in ACL Reconstruction: the Influence of Gender and Race on Incidence, Treatment, and Outcomes

PURPOSE OF REVIEW

Anterior cruciate ligament (ACL) rupture is a common injury that has important clinical and economic implications. We aimed to review the literature to identify gender, racial and ethnic disparities in incidence, treatment, and outcomes of ACL injury.

RECENT FINDINGS

Females are at increased risk for ACL injury compared to males. Intrinsic differences such as increased quadriceps angle and increased posterior tibial slope may be contributing factors. Despite lower rates of injury, males undergo ACL reconstruction (ACLR) more frequently. There is conflicting evidence regarding gender differences in graft failure and ACL revision rates, but males demonstrate higher return to sport (RTS) rates. Females report worse functional outcome scores and have worse biomechanical metrics following ACLR. Direct evidence of racial and ethnic disparities is limited, but present. White athletes have greater risk of ACL injury compared to Black athletes. Non-White and Spanish-speaking patients are less likely to undergo ACLR after ACL tear. Black and Hispanic youth have greater surgical delay to ACLR, increased risk for loss to clinical follow-up, and less physical therapy sessions, thereby leading to greater deficits in knee extensor strength during rehabilitation. Hispanic and Black patients also have greater risk for hospital admission after ACLR, though this disparity is improving. Females have higher rates of ACL injury with inconclusive evidence on anatomic predisposition and ACL failure rate differences between genders. Recent literature has suggested inferior RTS and functional outcomes following ACLR in females. Though there is limited and mixed data on incidence and outcome differences between races and ethnic groups, recent studies suggest there may be disparities in those who undergo ACLR and time to treatment.

Regression model for predicting knee flexion angles using ankle plantar flexion angles, body mass index and generalised joint laxity

Increased knee flexion angles are associated with reduced non-contact anterior cruciate ligament (ACL) injury risks. Ankle plantar flexion angles and internal risk factors could influence knee flexion angles, but their correlations are unknown. This study aimed to establish and validate a regression model to predict knee flexion angles using ankle plantar flexion angles, body mass index (BMI) and generalised joint laxity (GJL) at initial contact of single-leg drop landings. Thirty-two participants performed single-leg drop landings from a 30-cm-high platform. Kinematics and vertical ground reaction forces were measured using a motion capture system and force plate. A multiple regression was performed, and it was validated using a separate data set. The prediction model explained 38% (adjusted R2) of the change in knee flexion angles at initial contact (p = 0.001, large effect size). However, only the ankle plantar flexion angle (p < 0.001) was found to be a significant predictor of knee flexion angles. External validation further showed that the model explained 26% of knee flexion angles (large effect size). The inverse relationship between ankle plantar flexion and knee flexion angles suggests that foot landing strategies could be used to increase knee flexion angles, thereby reducing non-contact ACL injury risks.

A Prediction Model for Primary Anterior Cruciate Ligament Injury Using Artificial Intelligence

Background

Supervised machine learning models in artificial intelligence (AI) have been increasingly used to predict different types of events. However, their use in orthopaedic surgery has been limited.

Hypothesis

It was hypothesized that supervised learning techniques could be used to build a mathematical model to predict primary anterior cruciate ligament (ACL) injuries using a set of morphological features of the knee.

Study Design

Cross-sectional study; Level of evidence, 3.

Methods

Included were 50 adults who had undergone primary ACL reconstruction between 2008 and 2015. All patients were between 18 and 40 years of age at the time of surgery. Patients with a previous ACL injury, multiligament knee injury, previous ACL reconstruction, history of ACL revision surgery, complete meniscectomy, infection, missing data, and associated fracture were excluded. We also identified 50 sex-matched controls who had not sustained an ACL injury. For all participants, we used the preoperative magnetic resonance images to measure the anteroposterior lengths of the medial and lateral tibial plateaus as well as the lateral and medial bone slope (LBS and MBS), lateral and medial meniscal height (LMH and MMH), and lateral and medial meniscal slope (LMS and MMS). The AI predictor was created using Matlab R2019b. A Gaussian naïve Bayes model was selected to create the predictor.

Results

Patients in the ACL injury group had a significantly increased posterior LBS (7.0° ± 4.7° vs 3.9° ± 5.4°; P = .008) and LMS (-1.7° ± 4.8° vs -4.0° ± 4.2°; P = .002) and a lower MMH (5.5 ± 0.1 vs 6.1 ± 0.1 mm; P = .006) and LMH (6.9 ± 0.1 vs 7.6 ± 0.1 mm; P = .001). The AI model selected LBS and MBS as the best possible predictive combination, achieving 70% validation accuracy and 92% testing accuracy.

Conclusion

A prediction model for primary ACL injury, created using machine learning techniques, achieved a >90% testing accuracy. Compared with patients who did not sustain an ACL injury, patients with torn ACLs had an increased posterior LBS and LMS and a lower MMH and LMH.

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 deep lateral femoral notch sign: a reliable diagnostic tool in identifying a concomitant anterior cruciate and anterolateral ligament injury

PURPOSE

The aim of the present study was to investigate the validity and reliability of the deep lateral femoral notch sign (DLFNS) in identifying a concomitant anterior cruciate ligament (ACL)/anterolateral ligament (ALL) rupture and predicting the clinical outcomes following an anatomical single-bundle ACL reconstruction. It was hypothesized that patients with a concomitant ACL/ALL rupture would have an increased DLFNS compared to patients without a concomitant ACL/ALL rupture.

METHODS

The lateral preoperative radiographs and MRI images of 100 patients with an ACL rupture and 100 control subjects were evaluated for the presence of a DLFNS and ACL/ALL rupture, respectively. The patients were evaluated clinically preoperatively and at a minimum 1 year following the ACL reconstruction. A receiver operator curve (ROC) analysis was performed to define the optimal cut-off value of the DLFNS for identifying a concomitant ACL/ALL injury. The relative risk (RR) was also calculated to determine whether the presence of the DLFNS was a risk factor for residual instability or ACL graft rupture following an ACL reconstruction.

RESULTS

The prevalence of DLFNS was 52% in the ACL-ruptured patients and 15% in the control group. At a minimum 1-year follow-up, 35% (6/17) of the patients with DLFNS > 1.8 mm complained of persistent instability, and an MRI evaluation demonstrated a graft re-rupture rate of 12% (2/17). In patients with a DLFNS < 1.8 mm, 8% (7/83) reported a residual instability, and the graft rupture rate was 2.4% (2/83). A DLFNS > 1.8 mm demonstrated a sensitivity of 89%, a specificity of 95%, a negative predictive value of 98%, and a positive predictive value of 89% in identifying a concomitant ACL/ALL rupture. Patients with a DLFNS > 1.8 mm had 4.2 times increased risk for residual instability and graft rupture compared to patients with a DLFNS ≤ 1.8 mm.

CONCLUSIONS

A DLFNS > 1.8 mm could be a clinically relevant diagnostic tool for identifying a concomitant ACL/ALL rupture with high sensitivity and PPV. Patients with a DLFNS > 1.8 mm should be carefully evaluated for clinical and radiological signs of a concomitant ACL/ALL rupture and treated when needed with a combined intra-articular ACL reconstruction and extra-articular tenodesis to avoid a residual rotational instability and ACL graft rupture.

LEVEL OF EVIDENCE

III.

Predictors of Pediatric Anterior Cruciate Ligament Injury: The Influence of Steep Lateral Posterior Tibial Slope and Its Relationship to the Lateral Meniscus

PURPOSE

To examine the relationship between posterior tibial slope and lateral meniscal bone angle (LMBA) on anterior cruciate ligament (ACL) tear risk in a pediatric population.

METHODS

In this case-control study, non-contact ACL-injured pediatric patients with no significant lateral meniscal lesions were matched by age and sex in a 1:1 ratio to a group of radiologically normal controls. Knee magnetic resonance imaging (MRI) studies were analyzed by 3 independent, blinded observers measuring the medial posterior tibial slope (MTS), lateral posterior tibial slope (LTS), and LMBA. Sagittal slope asymmetry was calculated as the absolute difference in degrees between slopes, and the relationship between LMBA and LTS was calculated as a ratio. Binary logistic regressions identified independent predictors of ACL injury. Receiver operator characteristics were performed to determine predictive accuracy.

RESULTS

20 study patients were compared with 20 sex- and age-matched controls (age 14.8 ± 2.42, mean ± standard deviation). LTS was significantly higher in the ACL-injured group (11.30° ± 3.52° versus 7.00° ± 2.63°, P = .0001), as were the absolute slope difference (7.10 ± 2.92° versus 3.14 ± 3.25°, P = .0002) and LTS:LMBA ratio (0.46 ± 0.17 versus 0.26 ± 0.12, P = .0001). No significant differences were observed for MTS or LMBA. Independent predictors were LTS (odds ratio [OR] 1.58, 95% confidence interval [CI] 1.18 to 2.13, P = .002), LTS:LMBA ratio (OR 3.13, 95% CI 1.48 to 6.62, P = .003), and absolute slope difference (OR 1.65, 95% CI 1.17 to 2.32, P = .005). LTS:LMBA ratio was the strongest predictor variable (area under the curve 0.86).

CONCLUSION

This study suggests that LTS, absolute slope difference, and LTS:LMBA ratio are significant pediatric ACL-injury risk factors. All 3 demonstrate good predictive accuracy; however, the relationship between steep LTS and shallow LMBA was the strongest predictor.

LEVEL OF EVIDENCE

III, case-control study.

Influence of Posterior Tibial Slope on Clinical Outcomes and Survivorship After Anterior Cruciate Ligament Reconstruction Using Hamstring Autografts: A Minimum of 10-Year Follow-Up

PURPOSE

To investigate the influence of medial and lateral posterior tibial slope (PTS) on long-term clinical outcomes and survivorship after anterior cruciate ligament (ACL) reconstruction using hamstring autografts.

METHODS

A total of 232 patients (mean age, 28.2 ± 8.9 years) who underwent primary ACL reconstruction from October 2002 to July 2007 were retrospectively reviewed. Patients with multiple ligament reconstruction, total meniscectomy, contralateral knee surgery before ACL reconstruction, open growth plate, and less than 10-year follow-up were excluded in the study. The medial and lateral PTS were measured from preoperative magnetic resonance imaging. Based on Li et al.'s previous study, the patients were divided into 2 groups according to their medial PTS (≤5.6° vs >5.6°) and lateral PTS (≤3.8° vs >3.8°), respectively. Clinical outcomes (clinical scores, stability tests and failure rate) were compared between the groups at the last follow-up. Furthermore, survival analysis was performed using the Kaplan-Meier method.

RESULTS

All clinical scores (International Knee Documentation Committee subjective, Lysholm, and Tegner activity scores) and stability tests (physical examinations and side-to-side difference in Telos stress radiographs) were insignificantly different between the 2 groups classified based on medial or lateral PTS. However, the failure rate was significantly higher in patients with medial PTS >5.6° (16.1% vs 5.1%, P = .01) or lateral PTS >3.8° (14.5% vs 4.7%; P = .01). The odds ratios of graft failure due to increased medial and lateral PTS were 3.18 (95% confidence interval, 1.22-8.28; P = .02) and 3.43 (95% confidence interval, 1.29-9.09; P = .01), respectively. In addition, the 10-year survivorship was significantly lower in patients with medial PTS >5.6° (83.9% vs 94.9%, P = .01) or lateral PTS >3.8° (85.5% vs 96.0%; P = .01).

CONCLUSIONS

Increased medial (>5.6°) and lateral (>3.8°) PTS were associated with higher failure rate and lower survivorship at a minimum of 10-year follow-up after primary ACL reconstruction using hamstring autografts.

LEVEL OF EVIDENCE

Level III, retrospective comparative trial.

Study of relationship of posterior tibial slope in anterior cruciate ligament injury

OBJECTIVE

To determine the relationship between Posterior Tibial slope in terms of medial and lateral in Anterior cruciate ligament deficient patients.

METHODS

Magnetic resonance images (MRI) of the knee of 100 ACL injured patients and 100 ACL intact patients were studied. Their medial and lateral posterior tibial slopes were measured using MRI. Of 200 subjects, 100 (Male- 63, Female- 37) were controls, other 100 (Male - 68, Female-32) were ACL injured cases. Using DIACOM viewer software,the slopes of both medial and lateral slopes were measured. Range of Variation, mean value and standard deviation of medial tibial plateau slope (MTS), lateral tibia plateau slope (LTS) of controls and ACL injured patients were measured. The data collected were entered into Microsoft excel worksheet and analysed using statistical package for social sciences, Version 15.0 (SPSS Inc. Chicago, IL, USA). Distribution of data was confirmed using Shapiro's Wilk Test and appropriate parametric statistics were applied. For all analysis p value < 0.05 was set to be significant.

RESULTS

In control (ACL uninjured) population mean MTS was 5.95° with SD 3.09°, mean LTS was 6.08° with SD 3.48°. In ACL injured population mean MTS 6.41° with SD 2.66°, mean LTS was 8.12° with SD 3.65°. So ACL injured population had MTS steeper than control population with no statistical significance (p value < 0.27) and LTS was steeper than control population with statistical significance (p value < 0.001),where as there were comparable results between male and females.

CONCLUSION

Our current results indicate that lateral PTS is a risk factor for patients with primary ACL tears as compared with ligament-intact controls. Therefore,PTS should be considered as independent modifiable risk factors in ACL injury.

Sex Differences in Anatomic Features Linked to Anterior Cruciate Ligament Injuries During Skeletal Growth and Maturation

BACKGROUND

Several anatomic features of the knee have been shown to affect joint and anterior cruciate ligament (ACL) loading and the risk of subsequent injuries. While several studies have highlighted sex differences between these anatomic features, little is known on how these differences develop during skeletal growth and maturation.

HYPOTHESES

(A) Anatomic features linked to an ACL injury will significantly change during skeletal growth and maturation. (B) The age-related changes in anatomic features linked to an ACL injury are different between male and female patients.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

After institutional review board approval, magnetic resonance imaging data from 269 unique knees (patient age 3-18 years; 51% female), free from any injuries, were used to measure femoral notch width, posterior slope of the lateral tibial plateau (lateral tibial slope), medial tibial depth, tibial spine height, and posterior lateral meniscal bone angle. Linear regression was used to test the associations between age and quantified anatomic indices. Patients were then divided into 4 age groups: preschool (3-6 years), prepubertal (7-10 years), early adolescent (11-14 years), and late adolescent (15-18 years). Also, 2-way analysis of variance with the Holm-Sidak post hoc test was used to compare morphology between male and female patients in each age group.

RESULTS

The femoral notch width, medial tibial depth, and tibial spine height significantly increased with age (P < .001). The lateral tibial slope decreased with age only in male patients (P < .001). Except for the posterior lateral meniscal bone angle, the age-related changes in anatomy were different between male and female patients (P < .05). On average, early and late adolescent female patients had smaller femoral notches, steeper lateral tibial slopes, flatter medial tibial plateaus, and shorter tibial spines compared with age-matched male patients (P < .01).

CONCLUSION

Overall, the findings supported our hypotheses, showing sex-specific changes in anatomic features linked to an ACL injury during skeletal growth and maturation. These observations help to better explain the reported age and sex differences in the prevalence of ACL injuries. The fact that most of these anatomic features undergo substantial changes during skeletal growth and maturation introduces the hypothesis that prophylactic interventions (ie, activity modification) would have the potential to reshape a maturing knee in a manner that lowers the risk of noncontact ACL injuries.

Knee Morphological Risk Factors for Anterior Cruciate Ligament Injury: A Systematic Review

BACKGROUND

Anterior cruciate ligament (ACL) reconstruction incidence has increased substantially in the past 25 years. Recently, there has been a focus on knee morphology as a contributor to ACL injury risk. The purpose of this study was to systematically review the literature to assess the influence of knee morphology on ACL injury.

METHODS

In accordance with PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, PubMed, Embase, and MEDLINE were searched in September 2017 for studies reporting on knee morphology and ACL injury. The search was updated in June 2018. The following inclusion criteria were used: English language; full text available; Level-I, II, or III evidence; human studies; and skeletally mature patients.

RESULTS

After systematically screening 6,208 studies, 65 studies met the inclusion/exclusion criteria. Three additional studies were identified in the search update, for a total of 68 studies comprising 5,834 ACL-injured knees. Intercondylar notch stenosis, most commonly defined by an "A-shaped" notch, decreased notch width, or decreased notch width index, was the most commonly reported femoral morphological risk factor for ACL injury. Increased femoral condylar offset ratio (>63%) and decreased condylar radius of curvature also were associated with an increased risk of ACL injury. Increased medial and lateral tibial slopes were the most commonly reported tibial risk factors. A smaller tibial eminence, reduced ACL size, and poor tibiofemoral congruity were also associated with increased injury risk.

CONCLUSIONS

Intercondylar notch stenosis, variations in sagittal condylar shape, increased tibial slope, reduced tibial eminence size, poor tibiofemoral congruity, and reduced ACL size are substantial risk factors for ACL injury. In future research, it would be valuable to identify a slope beyond which slope correction should be performed concomitantly with ACL reconstruction, and to determine whether an optimal relationship of notch size to graft size exists. To achieve optimal outcomes, the osseous morphological risk factors should be considered in individualized anatomic ACL reconstructions.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Tibial slope and medial meniscectomy significantly influence short-term knee laxity following ACL reconstruction

PURPOSE

To determine demographic, anatomic, and surgical factors associated with static and dynamic Anterior Tibial Translation (ATT) following ACL reconstruction. The hypothesis was that both static and dynamic ATT would be greater in knees with high tibial slope or that required meniscectomy.

METHODS

The authors prospectively enrolled 280 consecutive patients that had primary ACL reconstruction using hamstring autografts at one center for which preoperative tear type, meniscal tears, and medial tibial slope were documented. A total of 137 were excluded due to concomitant extra-articular tenodesis or surgical antecedents on either knee, and 18 were lost to follow-up, leaving 125 that were evaluated at a minimum of 6 months including: static ATT on monopodal weight-bearing radiographs, and dynamic ATT on differential stress radiographs using the Telos™ device.

RESULTS

Both postoperative static and dynamic ATT were strongly associated with preoperative static and dynamic ATT (respectively, β = 0.068 and β = 0.50, p < 0.001). Multivariable regression confirmed that postoperative static ATT increased with tibial slope (β = 0.24; CI 0.01-0.47; p = 0.042) and in knees that had partial medial meniscectomy (β = 2.05; CI 0.25-3.84; p = 0.025), while dynamic ATT decreased with age (β = - 0.11; CI - 0.16 to - 0.05; p < 0.001), and increased with tibial slope (β = 0.27; CI 0.04-0.49; p = 0.019) and in knees that had partial medial meniscectomy (β = 2.20; CI 0.35-4.05; p = 0.019).

CONCLUSION

Both static and dynamic ATT following ACL reconstruction increased with tibial slope and in knees that had partial medial meniscectomy. These findings could help surgeons tailor their techniques and 'à la carte' rehabilitation protocols, by preserving the menisci and sometimes delaying full weight-bearing and return to sport in patients at risk, and hence improve outcomes and prevent graft failures.

STUDY DESIGN

Cohort study.

LEVEL OF EVIDENCE

V.

External loads associated with anterior cruciate ligament injuries increase the correlation between tibial slope and ligament strain during in vitro simulations of in vivo landings

BACKGROUND

The aim of the present study was to evaluate the relationship between tibial slope angle and ligament strain during in vitro landing simulations that induce ACL failure through the application of variable external loading at the knee. The hypothesis tested was that steeper posterior tibial slope angle would be associated with higher ACL strain during a simulated landing task across all external loading conditions.

METHODS

Kinetics previously derived from an in vivo cohort performing drop landings were reproduced on 45 cadaveric knees via the mechanical impact simulator. MRIs were taken of each specimen and used to calculate medial compartment posterior tibial slope, lateral compartment posterior tibial slope, and coronal plane tibial slope. Linear regression analyses were performed between these angles and ACL strain to determine whether tibial slope was a predictive factor for ACL strain.

FINDINGS

Medial and lateral posterior tibial slope were predictive factors for ACL strain during some landings with higher combined loads. Medial posterior slope was more predictive of ACL strain in most landings for male specimens, while lateral posterior and coronal slope were more predictive in female specimens, but primarily when high abduction moments were applied.

INTERPRETATION

Tibial slope has the potential to influence ACL strain during landing, especially when large abduction moments are present at the knee. Deleterious external loads to the ACL increase the correlation between tibial slope and ACL strain, which indicates that tibial slope angles are an additive factor for athletes apt to generate large out-of-plane knee moments during landing tasks.

20-Year Outcomes of Anterior Cruciate Ligament Reconstruction With Hamstring Tendon Autograft: The Catastrophic Effect of Age and Posterior Tibial Slope

BACKGROUND

No well-controlled studies have compared the long-term outcome of anterior cruciate ligament (ACL) reconstruction with hamstring tendon autograft between adolescents and adults. Increased posterior tibial slopes (PTSs) have been reported in the ACL-injured versus controls, but the effect of PTS on the outcome after reconstruction is relatively unexplored.

PURPOSE

To compare the prospective longitudinal outcome of "isolated" ACL ruptures treated with anatomic endoscopic ACL reconstruction using hamstring tendon autograft over 20 years in adolescent and adult cohorts and to examine factors for repeat ACL injury.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

A single-surgeon series of 200 consecutive patients undergoing isolated primary ACL reconstruction with hamstring tendon autograft were prospectively studied. Subjects were assessed preoperatively and at 2, 7, 15, and 20 years postoperatively. Outcomes included International Knee Documentation Committee (IKDC) Knee Evaluation, IKDC subjective scores, KT-1000 instrumented laxity testing, and radiological evaluation of degenerative change and medial tibial slope. Twenty-year outcomes were compared between those who underwent surgery at the age of 18 years or younger (adolescent group, n = 39) and those who underwent surgery when older than 18 years (adult group, n = 161).

RESULTS

At 20 years, 179 of 200 subjects were reviewed (89.5%). ACL graft rupture occurred in 37 subjects and contralateral ACL injury in 22 subjects. Of those with intact ACL grafts at 20 years, outcomes were not statistically different between adolescents and adults for the variables of IKDC subjective score ( P = .29), return to preinjury activity level ( P = .84), current activity level ( P = .69), or degree of radiological degenerative change at 20 years ( P = .51). The adolescent group had a higher proportion of grade 1 ligamentous laxity testing compared with the adult group ( P = .003). Overall, ACL graft survival at 20 years was 86% for adults and 61% for adolescents (hazard ration, 3.3; P = .001). The hazard for ACL graft rupture was increased by 4.8 in adolescent males and 2.5 in adolescent females compared with adults. At 20 years, the ACL survival for adolescents with a PTS of ≥12° was 22%. The hazard for ACL graft rupture was increased by 11 in adolescents with a PTS of ≥12° ( P = .001) compared with adults with a PTS <12°.

CONCLUSION

Repeat ACL injury after isolated ACL reconstruction is common, occurring in 1 in 3 over 20 years. In the absence of further injury, isolated ACL reconstruction using this technique was associated with good long-term outcomes with respect to patient-reported outcomes and return to sports, regardless of age. However, mild ligament laxity and ACL graft rupture after ACL reconstruction are significantly more common in adolescents, especially adolescent males, compared with adults. PTS of 12° or more is the strongest predictor of repeat ACL injury, and its negative effect is most pronounced in adolescents.