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

Medial and Lateral Posterior Tibial Slope in the Skeletally Immature: Variability Across Pediatric Ages Without a Consistent Trend

INTRODUCTION

Increased knee posterior tibial slope (PTS) angle elevates anterior cruciate ligament (ACL) strain and ACL injury risk. Adult biomechanical research indicates that decreasing the PTS may reduce ACL injuries. Younger patients have much higher risk of ACL injury than adults, with limited anatomic research on tibial slope. The purpose of this study is to evaluate the pediatric medial and lateral PTS in a larger cohort group than prior research.

METHODS

83 CT scans of the knee from children aged <2 to 11 were evaluated using OsiriX imaging software. The PTS was evaluated at two distinct points on sagittal CT sections: (1) At the medial and 2) lateral tibial plateaus, both aligned with the central part of the coronal view of the femoral condyles.

RESULTS

The medial and lateral PTS demonstrated variability across ages <2 to 11, with mean values ranging from 3.6° ± 1.8° to 8.7° ± 5.3° for medial slopes and 5.1° ± 3.3° to 12.4° ± 3.6° for lateral slopes. The proportion of patients with at least one slope >10° peaked at age 8 (100%) and age 6 (67%). Simple linear regression revealed no statistically significant relationship between age and tibial slope for medial (coefficient of -0.07, p = 0.574, R2 = 0.004) or lateral slopes (coefficient of -0.08, p = 0.459, R2 = 0.007).

CONCLUSION

Corrective osteotomy of increased PTS to lower the risk of ACL injury may be performed in high injury risk adult patients. However, such invasive procedures are not recommended for the skeletal immature because osteotomy in the growth plates in the proximal tibia could induce growth disturbance. In a unique skeletally immature patient with high risk of recurrent ACL injury, guided growth might be an option in high risk for lowering PTS in a controlled manner. As younger patients have some of the higher risks of primary and recurrent ACL injury, future research in this area may offer another approach to lower the risk of these injuries.

LEVEL OF EVIDENCE

Level III.

Increased Posterior Tibial Slope is a Risk Factor for Anterior Cruciate Ligament Injury and Graft Failure After Reconstruction: A Systematic Review

IMPORTANCE

Anterior cruciate ligament (ACL) injury and ACL reconstruction (ACLR) graft failure are important clinical concerns that result in long recovery periods, potential long-term knee instability and poor patient outcomes. Identifying risk factors such as posterior tibial slope (PTS), meniscal slope (MS) and meniscal bone angle (MBA) is important for improving risk stratification, guiding management decisions and reducing the incidence of both ACL injury and ACLR graft failure.

OBJECTIVE

This systematic review and meta-analysis aims to determine whether increased PTS, increased MS and decreased MBA serve as independent predictors of both ACL injury and ACLR graft failure.

EVIDENCE REVIEW

A comprehensive search of the literature was conducted following PRISMA guidelines. For evaluating ACL injury, the review included comparative studies measuring PTS, MS, or MBA between ACL injury patients and ACL-intact controls. For ACLR graft failure, studies comparing these measurements between patients with ACLR graft failures and those with successful ACLR outcomes were included. Data was pooled using a random-effects model to calculate the overall mean difference (MD) between groups.

FINDINGS

Out of 1,683 initially identified studies, 75 studies were selected for detailed analysis, 53 analyzing ACL injury and 24 studies analyzing ACLR graft failure. The meta-analysis revealed that increased PTS significantly increases the risk of both ACL injury (MD 1.64°; 95%CI 1.08-2.20, p<0.01) and ACLR graft failure (MD 1.76°; 95%CI 1.03-2.48, p<0.01). This is statistically significant for both lateral and medial PTS, and across both radiograph and MRI. A higher lateral MS (MD 3.25°; 95%CI 1.70-4.80, p<0.01) and a lower lateral MBA (MD -3.85°; 95%CI -6.38--1.32, p<0.01) were also significantly associated with an increased risk of ACL injury. However, no statistically significant differences were observed for MS or MBA between ACLR graft failure and successful ACLR groups.

CONCLUSION

and Relevance: The findings indicate that increased PTS, whether measured medially or laterally, is a statistically significant risk factor for both ACL injury and ACLR graft failure. Additionally, increased lateral MS and decreased lateral MBA are associated with ACL injury. This evidence supports the consideration of tibial slope in risk assessment, preoperative planning, and surgical decision-making for both prevention of ACL injury and ACLR procedures. Further research is necessary to fully understand the role of MS and MBA in ACL injury.

LEVEL OF EVIDENCE

Level IV; systematic review of level III-IV studies.

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.

A small notch width index, steeper medial and lateral tibial slope and higher lateral/medial tibial slope ratio are relevant knee morphological factors for ACL injuries in skeletally immature patients-A systematic review

Purpose

The incidence of anterior cruciate ligament (ACL) injuries in skeletally immature patients has drastically increased over the last decades. Morphology of the knee might play an important role. This literature review provides a systematic overview of knee morphological factors relevant to ACL injury in skeletally immature patients. The hypothesis of the present study is that multiple knee morphological parameters-such as a steep medial and lateral tibial slope (MTS and LTS) and a narrow intercondylar notch-can be identified as potentially relevant factors for ACL injury in this population.

Methods

Systematic review according to PRISMA guidelines. MEDLINE, Embase and Cochrane were searched in December 2023 for studies reporting on knee morphology and ACL injury in skeletally immatures. The following inclusion criteria were used: English/Dutch studies, full-text available, human studies and skeletally immature patients. Parameters with clinical homogeneity and presented in two or more studies as means with standard deviation were included in a meta-analysis using RevMan. Parameters that could not be included in the meta-analyses were presented in a descriptive manner.

Results

After screening 1825 studies, a total of 18 studies were included, of which 16 studies had parameters included in the meta-analyses. These studies investigated 31 knee morphological factors for ACL injury in skeletally immatures. Meta-analyses identified a smaller notch width index (NWI) (0.25 vs. 0.26, mean difference: -0.02 95% confidence interval [CI]: -0.03 to -0.01, p ≤ 0.00001) steeper MTS and LTS (4.8° vs. 3.6° (mean difference: 0.55° 95% CI: 0.09-1.01, p = 0.02) and 4.3° vs 2.8° (mean difference: 2.04° 95% CI: 0.75-3.32, p = 0.0003), respectively) and higher LTS/MTS ratio as risk factors for ACL injury in skeletally immature patients.

Conclusions

A small NWI, steeper MTS and LTS and higher LTS/MTS ratios were identified as relevant knee morphological factors for ACL injuries in skeletally immature patients.

Level of Evidence

Level III.

Comparison of coronal and sagittal alignment in patients without osteoarthritis but with knee complaints

Purpose

This study aimed to clarify lower limb alignment characteristics and the relationship between coronal and sagittal lower limb alignment in Japanese patients with knee complaints but without knee osteoarthritis (KOA).

Methods

This retrospective study included 200 knees from Japanese patients with knee complaints but without KOA aged 60 years and under presenting with knee complaints between May 2020 and May 2023. We assessed coronal parameters, including mechanical hip knee angle (mHKA), arithmetic HKA (aHKA) mechanical lateral distal femoral angle and medial proximal tibial angle (MPTA), and sagittal parameters, such as medial posterior tibial slope (MPTS) and lateral posterior tibial slope (LPTS). In addition, we compared differences between CPAK types.

Results

A weak positive correlation was found between mHKA and MPTS, but not with aHKA. Moderate negative and moderate positive correlations were found between mHKA and MPTA and between medial and LPTS, respectively.

Conclusions

Little correlation was found between the coronal and sagittal parameters in patients with knee complaints but without KOA.

Level of Evidence

Level Ⅲ.

Evaluating the Mechanical Axis for Detection of Posterior Tibial Slope Malalignment in ACL-Deficient Knees on Lateral Radiographs

Background

Distal tibial deformities are not assessed using the proximal anatomical axis (PAA) to determine the posterior tibial slope (PTS). Therefore, it seems advantageous to measure PTS on full-length lateral tibial radiographs using the mechanical axis (MA).

Purposes

To (1) compare the PTS measurements using the MA and the PAA and (2) determine whether using the PAA fails to detect a certain number of significantly elevated PTS values compared with using the MA.

Study Design

Cohort study (Diagnosis); Level of evidence, 3.

Methods

Full-length lateral tibial radiographs of 218 consecutive cases were reviewed. Radiographs were checked for malrotation. Therefore, the distance between the posterior tibial condyles was measured in millimeters. Patients with a difference of ≥7 mm between the posterior tibial condyles were excluded, leaving 196 cases for the final statistical analysis. The PTS was measured using the MA and the PAA. Differences between these 2 techniques were analyzed. The sensitivity and specificity of the PAA as a screening method for pathological PTS were calculated, with the MA as the standard for comparison. Four subgroups were formed, all with PAA <12° and different lower limits for the MA: group 1, MA ≥10°; group 2, MA ≥10.5°; group 3, MA ≥11°; and group 4, MA ≥11.5°.

Results

Radiographs with ≥7 mm between the posterior tibial condyles showed an increased inconsistency between the PTS measurement with the MA and the PAA. In the group with a distance of <7 mm between the posterior tibial condyles (n = 196), the mean PTS measured with the MA was 9.4°± 3.8° (range, 0.4° to 21.9°), and the mean PTS was 10.5°± 3.5° (range, 1.7° to 20.9°) according to the PAA. The mean difference in PTS between the PAA and the MA was 1.1°± 1.2° (range, -2.4° to 4.1°; P < .001). Group 1 had a sensitivity of 73% and specificity of 98%; group 2, sensitivity of 84% and specificity of 97%; group 3, sensitivity of 87% and specificity of 93%; and group 4, sensitivity of 95% and specificity of 89%.

Conclusion

Measuring the PTS using the MA was advantageous, as the measurement with the PAA did not correctly identify all cases with sagittal alignment changes. The proportion of patients with pathologically increased PTS not identified with the proximal anatomical measurement, reflected by the sensitivity, depended on the threshold value defined for the MA. Lateral radiographs, showing an increased distance between the posterior tibial condyles, indicated malrotation of the tibia leading to measurement inaccuracy.

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.

Posterior tibial slope angle in contact versus non-contact anterior cruciate ligament injuries

BACKGROUND

Increased Posterior Tibial Slope (PTS) angle has been reported to be a risk factor for primary anterior cruciate ligament (ACL) tears. However, it is unknown whether increased PTS has an associated increased risk for non-contact versus contact ACL injury.

PURPOSE

The purpose of this study is to determine whether patients with non-contact ACL injury have a higher PTS angle than those with contact ACL injury.

METHODS

A total of 1700 patients who underwent primary ACL reconstruction between January 2011 and June 2023 at a single academic institution were initially included. Electronic medical records were reviewed for demographic information as well as evidence that the patient sustained a contact or non-contact ACL injury. Patients in the contact cohort were propensity score matched to patients in the non-contact cohort by age, sex and BMI. Additionally, patients in the contact cohort were then propensity score matched to a control group of patients with intact ACLs also by age, sex and BMI.

RESULTS

One hundred and two patients with contact injury were initially identified and 1598 patients with non-contact injuries were identified. Of the 102, 67 had knee X-rays that were suitable for measurement. These 67 contact injury patients were propensity score matched to 67 noncontact patient and 67 patients with intact ACLs based on age, sex and BMI. There were no significant differences between contact and non-contact cohorts in age (28.7±6.3 vs. 27.1±6.5, p = 0.147), sex (Female: 36.0% vs. 34.3%, p = 0.858), or BMI (26.7±5.6 vs 26.1±3.4, p = 0.475). There was no significant difference in PTS angle between contact versus non-contact ACL injury patients (11.6±3.0 vs.11.6±2.8, p = 0.894). There was a significant difference in PTS between the contact ACL injury and the intact cohort (11.6±3.0 vs. 10.0±3.9, p = 0.010) and the non-contact ACL injury and the intact cohort (11.6±2.8 vs. 10.0±3.9, p = 0.010).

CONCLUSION

There was no significant difference in the degree of PTS between patients who sustained contact versus non-contact ACL injuries. Additionally, there was a significantly increased PTS in both the contact and non-contact ACL injury cohorts compared to patients with intact ACLs.

Tibiofemoral bone configuration is not associated with hamstring muscle strength in male and female patients with ACL reconstruction

PURPOSE

Previous evidence indicated that the tibiofemoral bone configuration might elevate the risk of an anterior cruciate ligament (ACL) injury. Furthermore, a low hamstring-to-quadriceps muscle ratio predisposes especially females to unfavourable knee kinematics. The primary objective of the present study was to investigate sex-specific associations between tibiofemoral bone geometry and isokinetic knee flexion torque in patients with primary ACL injury followed by ACL reconstruction.

METHODS

N = 100 patients (72 = male, 28 = female, age = 31.3 ± 10.2, body mass index = 25.3 ± 3.6) with primary ACL rupture with isokinetic knee flexion torque assessments before and 6 months after ACL reconstruction surgery were analysed. Magnetic resonance imaging scans were analysed for medial posterior tibial slope (MPTS) and lateral posterior tibial slope, notch width index (NWI) and lateral femoral condyle index (LFCI). Additionally, isokinetic knee flexion torque (60°/s) and hamstring-quadriceps ratios were evaluated. Subsequently, functional parameters were correlated with imaging data for gender subgroups.

RESULTS

The findings showed that presurgical isokinetic knee flexion torque was not associated with any marker of femoral or tibial bone geometry. Further, while significant differences were observed between female (0.883 ± 0.31 Nm/kg) and male (1.18 ± 0.35 Nm/kg) patients regarding preoperative normalized knee flexion torque (p < 0.001), no significant sex differences were found for percentage increases in normalized knee flexion torque from presurgery to postsurgery. Generally, female patients demonstrated significantly higher MPTS magnitudes (p < 0.05) and lower LFCI values (p < 0.05) compared to men.

CONCLUSION

The present results demonstrated no association between tibial or femoral bone geometry and muscle strength of the hamstrings in patients with ACL reconstruction, indicating an important mismatch of muscular compensation to deviations in bone geometry. There were no sex-specific differences in tibiofemoral bone parameters.

LEVEL OF EVIDENCE

Level III.

Anterior Cruciate Ligament Reconstruction in Patients Aged 50 Years and Older Results in Improvements in Activity and Functional Outcome Measures, Whereas Reported Complication Rates Vary Widely: A Systematic Review

PURPOSE

To systematically review the contemporary literature and evaluate patient-reported outcome measures (PROMs), functional knee measures, and the incidence of complications in patients aged 50 years and older undergoing anterior cruciate ligament reconstruction (ACLR) at short- to mid-term follow-up.

METHODS

A literature search was conducted across the PubMed, Embase, and Scopus databases, spanning from database inception to November 2023, in accordance with the 2020 Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. The inclusion criteria consisted of clinical studies reporting PROMs, measures of knee stability, and complication rates after ACLR in patients aged 50 years and older with minimum 2-year follow-up. The Methodological Index for Non-randomized Studies criteria were used to assess study quality. Primary outcome measures consisted of changes in PROMs and complication rates after ACLR.

RESULTS

A total of 17 studies, consisting of 1,163 patients undergoing ACLR, were identified. Autografts were used in 90.3% of patients, whereas 9.7% of patients were treated using allografts. At minimum 24-month follow-up, mean International Knee Documentation Committee scores ranged from 67.4 to 92.96; mean Lysholm scores, from 84.4 to 94.8; and mean Tegner scores, from 0.3 to 5.4. The mean side-to-side difference at final follow-up ranged from 1.2 to 2.4 mm, and the rates of recurrent instability ranged from 0% to 18%. Complication and revision rates ranged from 0% to 40.4% and 0% to 37.5%, respectively, with the highest rates observed in studies noting a high incidence of intraoperative cartilage lesions.

CONCLUSIONS

ACLR in patients aged 50 years and older results in favorable International Knee Documentation Committee scores, Lysholm scores, and Tegner activity scores and improvements in functional knee measures. However, a wide range of reoperations and complications are reported, attributed to varying levels of chondral injury and osteoarthritis, which warrant consideration when discussing expectations in patients aged 50 years and older undergoing ACLR.

LEVEL OF EVIDENCE

Level IV, systematic review of Level II to IV studies.

Demographic and Injury Characteristics as Potential Risk Factors for Anterior Cruciate Ligament Injuries: A Multicentric Cross-Sectional Study

Background: Anterior cruciate ligament (ACL) injuries are prevalent and can have debilitating consequences, with various factors potentially influencing their occurrence. This multicentric study aimed to comprehensively analyze the epidemiological characteristics of ACL injuries. We hypothesized that specific patient characteristics, such as age, sex, body mass index (BMI), and sports involvement, would be associated with distinct injury patterns and risk profiles. Methods: This cross-sectional study analyzed the medical records of 712 patients aged 15-60 diagnosed with ACL rupture. Data on demographics, injury mechanisms, associated injuries, graft type, and sports involvement were collected. Results: The majority of patients were male (93.1%), aged 15-30 years (80.2%), and overweight (66.7%). Autografts were the predominant graft choice (96.07%). Associated injuries were present in 79.5% of cases, with medial meniscus ruptures being the most common (37.36%). Sports-related (49.3%) and non-sports-related (50.7%) injuries were nearly equal, with non-contact injuries more prevalent (71.1%). In the sports-related subgroup, associated injuries emerged as a significant risk factor for ACL rupture (p = 0.014, OR = 1.596, 95% CI: 1.101-2.314), whereas non-contact mechanisms showed borderline significance (OR = 0.75, p = 0.09). Moreover, younger athletes were more susceptible to sports-related injuries (p = 0.024), with football being the primary sport involved. Conclusions: This study identified a high prevalence of concomitant injuries with ACL injury, which increased the risk of ACL injury, particularly in sports-related cases. Age-related differences in injury patterns highlight the need for age-appropriate preventive measures, especially for younger athletes participating in high-risk sports. This underscores the need for comprehensive injury assessment, targeted prevention strategies, and optimized clinical management approaches tailored to different populations' specific characteristics and risks.

Precise and efficient measurement of tibial slope on magnetic resonance imaging (MRI): two novel autonomous pipelines by traditional and deep learning algorithms

Background

The measurement of posterior tibial slopes (PTS) can aid in the screening and prevention of anterior cruciate ligament (ACL) injuries and improve the success rate of some other knee surgeries. However, the circle method for measuring PTS on magnetic resonance imaging (MRI) scans is challenging and time-consuming for most clinicians to implement in practice, despite being highly repeatable. Currently, there is no automated measurement scheme based on this method. To enhance measurement efficiency, consistency, and reduce errors resulting from manual measurements by physicians, this study proposes two novel, precise, and computationally efficient pipelines for autonomous measurement of PTS.

Methods

The first pipeline employs traditional algorithms with experimental parameters to extract the tibial contour, detect adhesions, and then remove these adhesions from the extracted contour. A cyclic process is employed to adjust the parameters adaptively and generate a better binary image for the following tibial contour extraction step. The second pipeline utilizes deep learning models for classifying MRI slice images and segmenting tibial contours. The incorporation of deep learning models greatly simplifies the corresponding steps in pipeline 1.

Results

To evaluate the practical performance of the proposed pipelines, doctors utilized MRI images from 20 patients. The success rates of pipeline 1 for central, medial, and lateral slices were 85%, 100%, and 90%, respectively, while pipeline 2 achieved success rates of 100%, 100%, and 95%. Compared to the 10 minutes required for manual measurement, our automated methods enable doctors to measure PTS within 10 seconds.

Conclusions

These evaluation results validate that the proposed pipelines are highly reliable and effective. Employing these tools can effectively prevent medical practitioners from being burdened by monotonous and repetitive manual measurement procedures, thereby enhancing both the precision and efficiency. Additionally, this tool holds the potential to contribute to the researches regarding the significance of PTS, particularly those demanding extensive and precise PTS measurement outcomes.

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

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

Is conventional magnetic resonance imaging superior to radiography in the functional integrity evaluation of anterior cruciate ligament in patients with knee osteoarthritis?

BACKGROUND

The functional integrity of the anterior cruciate ligament (ACL) influences surgical decision-making in patients with knee osteoarthritis (KOA). This study aimed to compare the diagnostic value of radiography and magnetic resonance imaging (MRI) in determining the functional status of ACL.

METHODS

We analyzed 306 knees retrospectively using preoperative hip-to-ankle anteroposterior standing (APS) radiographs, anteroposterior (AP) and lateral knee radiographs, AP valgus stress (VS) force radiographs, and standard orthogonal MRI. Based on the intraoperative visualization, the knees were grouped into ACL functionally-intact and ACL functionally-deficient (ACLD) groups. The diagnostic validity and reliability were calculated based on the radiograph parameters such as hip-knee-ankle angle (HKA), medial proximal tibial angle (MPTA), lateral distal femoral angle (LDFA), posterior tibial slope (PTS), sagittal tibiofemoral subluxation (STFS), coronal tibiofemoral subluxation (CTFS), joint line convergence angle (JLCA), the maximum wear point of the proximal tibia plateau (MWPPT%), and MRI parameters including ACL grades and MWPPT%.

RESULTS

HKA, MPTA, PTS, STFS, JLCA, and CTFS on APS and AP radiographs, and MWPPT% on radiographs and MRI showed a significant diagnostic value (P < 0.05). There were no statistically significant differences in the single parameters from radiographs and MRI. After constructing the logistic regression models, MRI showed higher sensitivity, specificity, and accuracy, reaching 96.8%, 79.9%, and 83.3%, respectively (P < 0.001).

CONCLUSIONS

In patients with KOA, the diagnostic value of single radiographic or MRI parameter in assessing the functional integrity of the ACL are equivalent. However, by constructing predictive models, MRI could significantly improve diagnostic validity compared with radiography.

Finite element graft stress for anteromedial portal, transtibial, and hybrid transtibial femoral drillings under anterior translation and medial rotation: an exploratory study

Stress concentration on the Anterior Cruciate Ligament Reconstruction (ACLr) for femoral drillings is crucial to understanding failures. Therefore, we described the graft stress for transtibial (TT), the anteromedial portal (AM), and hybrid transtibial (HTT) techniques during the anterior tibial translation and medial knee rotation in a finite element model. A healthy participant with a non-medical record of Anterior Cruciate Ligament rupture with regular sports practice underwent finite element analysis. We modeled TT, HTT, AM drillings, and the ACLr as hyperelastic isotropic material. The maximum Von Mises principal stresses and distributions were obtained from anterior tibial translation and medial rotation. During the anterior tibia translation, the HTT, TT, and AM drilling were 31.5 MPa, 34.6 Mpa, and 35.0 MPa, respectively. During the medial knee rotation, the AM, TT, and HTT drilling were 17.3 MPa, 20.3 Mpa, and 21.6 MPa, respectively. The stress was concentrated at the lateral aspect of ACLr,near the femoral tunnel for all techniques independent of the knee movement. Meanwhile, the AM tunnel concentrates the stress at the medial aspect of the ACLr body under medial rotation. The HTT better constrains the anterior tibia translation than AM and TT drillings, while AM does for medial knee rotation.

[Magnetic resonance imaging of the knee joint : What does the orthopedic surgeon expect from the radiologist?]

Magnet resonance imaging (MRI) offers a precise visualization of structural changes with high sensitivity and specificity. However, not all these soft tissue damages or bony lesions are clinically relevant or require treatment. Therefore, it is important to provide the radiologist with a specific clinical request when asking for an MRI examination of the knee. In this article, all important anatomical structures of the knee joint will be addressed with emphasis on the relevant questions for the radiologist. Based on the clinical examination, the MRI provides information about the damage of anatomical structures. This information is of utmost importance for therapeutic decision-making in order to allow an adequate and personalized treatment of patients.

Anterior Proximal Tibial Screw Hemiepiphysiodesis Decreases Posterior Tibial Slope in Knee Flexion Contracture: A Case Report

CASE

A 13-year-old adolescent boy with hemiplegic cerebral palsy suffering from fixed knee flexion deformity of 10° despite extensive conservative treatment. Owing to a posterior tibial slope (PTS) of 16°, anterior hemiepiphysiodesis was applied to the proximal tibia. The 2 screws were removed after 9 months. Final follow-up at 16 months showed complete knee extension and a PTS of 4°.

CONCLUSION

The presented technique is a good alternative in knee flexion deformity with an increased PTS and has surprisingly not been described in the literature. This might be worth considering for other pathologies such as pediatric anterior cruciate ligament injury with an increased PTS.

Correlation between vascular endothelial growth factor A gene polymorphisms and tendon and ligament injury risk: a systematic review and meta-analysis

BACKGROUND

Relevant evidence suggests that angiogenic factors contribute significantly to fibril matrix reconstruction following physical injuries to tendon ligaments. Vascular endothelial growth factor A (VEGFA), with its potent angiogenic effect, has been studied extensively, and its functional polymorphisms, including rs699947, rs1570360, and rs2010963, have been the focus of numerous investigations. Some scholars have explored the association between gene polymorphisms in the VEGFA and the risk of tendon ligament injury, but the findings are not entirely consistent.

OBJECTIVES

The purpose of this study was to investigate the association between rs699947, rs1570360, and rs2010963 gene polymorphisms in VEGFA and the risk of tendon and ligament injuries.

METHODS

After including articles about the association of VEGFA rs699947, rs1570360, and rs2010963 polymorphisms with tendon and ligament injuries according to the search strategy, we assessed their quality and conducted meta-analyses to examine the link between these polymorphisms and the risk of tendon and ligament injuries using odds ratios and 95% confidence intervals.

RESULTS

Of 86 related articles, six were included in the meta-analysis. Some of these suggest an association between VEGFA rs2010963 and the risk of tendon and ligament injury in the population, with the specific C allele being one of the adverse factors for knee injury. Some studies suggest that VEGFA rs699947 and VEGFA rs1570360 single-nucleotide polymorphisms are associated with anterior cruciate ligament rupture. The risk of non-contact anterior cruciate ligament rupture is nearly doubled in individuals with the rs699947 CC genotype compared to the control group. Our analysis did not find any significant relationship between VEGFA gene polymorphisms (rs699947, rs1570360, and rs2010963) and the chance of tendon and ligament injury without consideration of race. However, the European population reveals that the CC genotype of VEGFA rs699947 can result in a greater risk of tendon and ligament injury, whereas the AG genotype for rs1570360 provides some protection. Additionally, rs2010963 was significantly associated with tendon and ligament injury; individuals with the C allele and the CC genotype had higher risk. False-positive report probability confirmed the high credibility of our results.

CONCLUSION

Overall, this study found no significant association between VEGFA rs699947, rs1570360, and rs2010963 polymorphisms and the risk of tendon ligament injury. However, in subgroup analysis, some genotypes of VEGFA rs699947, rs1570360, and rs2010963 were found to increase the risk of tendon ligament injury in European populations.

[Influence of the bony alignment on the ligaments of the knee joint]

In recent years biomechanical and clinical studies have shown that the three-dimensional bony alignment of the lower extremities has a relevant influence on the ligamentous structures of the knee and consequently on the stability of the knee joint. Therefore, in the case of pathological ligamentous damage of the knee joint, a possible malalignment must always be thoroughly evaluated and if necessary, included in the treatment planning. Varus malalignment plays an important role especially with respect to the cruciate ligaments as well as the posterolateral ligamentous structures and has been identified as a significant risk factor for failure after surgical reconstruction of these ligamentous structures. Similar data have also been published for valgus malalignment particularly with respect to its negative influence on the anterior cruciate ligament and the medial capsuloligamentous complex. Alignment deviations in the sagittal plane, especially the inclination of the tibial articular surface (slope), have been extensively investigated in several recent studies. It has been demonstrated that the tibial slope has a relevant influence on the anteroposterior stability of the knee joint and hence on the cruciate ligaments. First clinical studies on the surgical correction of the axis in selected patients showed very promising results with the potential of protecting ligament reconstructions against repeated failure; however, further data especially regarding the importance and the exact indications for an additional alignment correction are necessary.

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.

The Posterior Tibial Slope Is Not Associated With Graft Failure and Functional Outcomes After Anatomic Primary Isolated Anterior Cruciate Ligament Reconstruction

BACKGROUND

Biomechanical studies have shown that an increased medial posterior tibial slope (MPTS) may affect anteroposterior knee laxity and tibial shear forces, ultimately increasing the risk for graft failure after anterior cruciate ligament (ACL) reconstruction. Previous clinical studies have, however, reported inconclusive results.

PURPOSE

The purpose of this study was to evaluate the relationship between the MPTS and graft failure as well as functional outcomes after anatomic primary isolated ACL reconstruction using a hamstring tendon autograft. It was hypothesized that an increased MPTS would be associated with a higher ACL graft failure rate. Furthermore, a higher MPTS would negatively correlate with functional outcomes in patients without ACL graft failure.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

Consecutive patients who underwent isolated primary ACL reconstruction with an anteromedial portal drilling technique between January 2011 and December 2019 were retrospectively reviewed. The MPTS was measured on preoperative lateral knee radiographs. At a minimum of 24 months postoperatively, the ACL graft failure rate and patient-reported outcome measures (PROM; International Knee Documentation Committee subjective knee form, Lysholm score, Tegner Activity Scale, visual analog scale for pain and subjective instability) were evaluated. Differences in the MPTS between patients with and without ACL graft failure as well as the frequency of graft failure between those with an MPTS <12° and those with an MPTS ≥12° were assessed for statistical significance. Binary logistic regression analysis was performed to stratify the risk of graft failure with the following variables: MPTS, age at surgery, and sex. Correlation analysis was performed to evaluate the relationship between the MPTS and PROM in patients without ACL graft failure.

RESULTS

In total, 326 patients were included (median follow-up, 71.0 months [IQR, 49.0-104.0 months]). There was no significant difference in the MPTS between patients with and without graft failure (10.6°± 3.2° vs 11.2°± 2.8°, respectively; P = .264). Additionally, there was no significant difference in the frequency of graft failure between patients with an MPTS <12° and those with an MPTS ≥12° (15.6% vs 16.5%, respectively; P = .835). Binary logistic regression showed that younger age at the time of surgery (odds ratio, 1.069 [95% CI, 1.031-1.109]) was associated with graft failure; sex and MPTS were not associated with graft failure. In patients without ACL graft failure, there was no significant correlation between the MPTS and PROM.

CONCLUSION

In patients who underwent anatomic primary isolated ACL reconstruction, an increased MPTS was not associated with a higher rate of graft failure or inferior functional outcomes. Younger age was a significant nonmodifiable risk factor for ACL graft failure.

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.