Safe femoral condyle range for the reverse Rigidfix femoral fixation device in anterior cruciate ligament reconstruction

Background: To determine the characteristics of cross-pin protrusion in patients treated with the reverse Rigidfix femoral fixation device for femoral tunnel preparation through the anteromedial portal in ACLR, analyse the reasons for this outcome, and identify safety hazards of this surgical technique for improvement. Methods: A retrospective analysis of patients who underwent ACLR using this technology at our hospital in 2018 was conducted. Patients with and without cross-pin protrusion were included in the case and control groups, respectively. The sex, age and imaging characteristics of the patients with cross-pin protrusion were identified, and the reasons for cross-pin protrusion were analysed. Results: There were 64 and 212 patients in the case and control groups, respectively. The proportion of cross-pin protrusion cases was 23.19% (64/276). There was a significant difference in the ratio of males to females (P <0.001, χ2=185.184), the mediolateral femoral condyle diameter (case group, 70.59 ±2.51 mm; control group, 82.65±4.16 mm; P <0.001, t=28.424), and the anteroposterior diameter of the lateral femoral condyle (case group, 58.34±2.89 mm; control group, 66.38±3.53 mm; P <0.001, t=16.615). The cross-pins did not penetrate the lateral femoral condyle cortex in patients with a mediolateral femoral condyle diameter ≥76 mm, but the cross-pins definitely penetrated the cortex when the diameter was ≤70 mm. The cross-pins did not penetrate when the anteroposterior lateral femoral condyle diameter was ≥66 mm, but the cross-pins definitely penetrated it when the diameter was ≤59 mm. Conclusion: The patients with cross-pin protrusion after reverse Rigidfix femoral fixation treatment to prepare the femoral tunnel through the anteromedial portal in ACLR were mainly females with small femoral condyles. For patients with a mediolateral femoral condyle diameter ≥76 mm and an anteroposterior lateral femoral condyle diameter ≥ 66 mm, there is no risk of cross-pin protrusion, so this technique can be used with confidence.

The Lateral Femoral Condyle Index Is Not a Risk Factor for Primary Noncontact Anterior Cruciate Ligament Injury

Background: The lateral femoral condyle index (LFCI)—a recently developed measure of the sphericity of the lateral femoral condyle—was reported to be a risk factor for anterior cruciate ligament (ACL) injury. However, issues have been raised regarding how the index was measured and regarding the patient group and the knee in which it was measured. Purpose: To investigate the association between the LFCI and the risk of sustaining a primary, noncontact ACL injury, and to examine whether this association was moderated by the posterior-inferior–directed slope of the lateral tibial plateau. Study Design: Cross-sectional study; Level of evidence, 3. Methods: A secondary analysis was conducted of deidentified magnetic resonance images of the uninjured knees of 86 athletes with ACL injury and the corresponding knees of 86 control athletes, matched for sports team, sex, and age. From those images, we measured the LFCI and the posterior-inferior–directed slope of the middle region articular cartilage surface of the tibial plateau’s lateral compartment. Conditional logistic regressions were performed to determine whether the LFCI was significantly associated with ACL injury risk and whether the lateral tibial compartment middle cartilage slope moderated this association. Data were analyzed for female and male participants separately as well as for both groups combined. Results: The LFCI was not found to be significantly associated with experiencing a primary, noncontact ACL injury for all analyses. The lateral tibial slope measure was not found to moderate the association between the LFCI and ACL injury. A conditional logistic regression analysis using the LFCI data of the injured knees, instead of the uninjured knees, of the participants with ACL injury revealed that the LFCI was significantly associated with ACL injury. Conclusion: In this population of athletically active female and male participants, the LFCI was not found to be a risk factor for noncontact ACL injury, regardless of the geometric features of the lateral tibial slope.

Increased Lateral Femoral Condyle Ratio Measured by MRI Is Associated with Higher Risk of Noncontact Anterior Cruciate Ligament Injury

Background Studies have shown a significant association between the radiographically measured lateral femoral condyle ratio (LFCR) and anterior cruciate ligament (ACL) injury. However, it is unclear whether the the LFCR measured by magnetic resonance imaging (MRI) is associated with risk of noncontact ACL injury. Objective 1 To investigate the effect of the LFCR on the risk of noncontact ACL injury by MRI. 2 To investigate the association of the LFCR measured by MRI with multiple bone morphological risk factors and evaluate the most sensitive risk predictors of noncontact ACL injury. Methods A total of 116 patients, including 58 subjects with noncontact ACL injury and 58 age-matched and sex-matched controls with only meniscus injury, were included in this retrospective case-control study. The LFCR, lateral tibial slope (LTS), lateral tibial height (LTH), medial tibial slope (MTS), and medial tibial depth (MTD) were measured on MRI. The differences in each index between the two groups were compared, and risk factors were screened by single-factor logistic regression analysis. Indicators with P values <0.1 were included in the logistic regression equation. The critical values and areas under the curve (AUCs) of independent risk factors were determined by receiver operating characteristic (ROC) curve analysis. Finally, the diagnostic performance of each risk factor was evaluated by the Z-test. Results A total of 116 patients who met the inclusion criteria were included in the final analysis (58 cases in the noncontact ACL injury group and 58 cases in the control group). Patients with noncontact ACL injury had a higher femoral LFCR (63.5±2.7%) than patients with simple meniscus tear. Among all the risk factors for ACL injury, the AUC for the LFCR was the largest, at 0.81 (95% CI, 0.73-0.88), and when the critical value was 61.35%, the sensitivity and specificity for the diagnosis of ACL injury were 79% and 67%, respectively. Combined with the LTH (> 2.35 mm), the diagnostic performance was improved. The AUC was 0.85 (95% CI, 0.78-0.92), the sensitivity was 0.83, and the specificity was 0.76 Conclusion This study shows that an increased LFCR is related to an increased risk of noncontact ACL injury by MRI. The LFCR and LTH are the most sensitive risk factors for noncontact ACL injury and may help clinicians identify individuals prone to ACL injury, allowing prevention and intervention measures to be applied.