Relationship between anterior tibial translation and bony morphology around the knee after anterior cruciate ligament injury / 中华骨科杂志

ABSTRACT

Objective:To investigate the relationship between anterior tibial translation (ATT) and bony morphology around the knee after anterior cruciate ligament (ACL) injury.Methods:A total of 67 patients diagnosed with acute ACL injury without any meniscal lesions were enrolled in this study between September 2019 and August 2020. Preoperative magnetic resonance imaging (MRI) scans were used to measure the ATT of the lateral compartment, and bony morphology was assessed by measuring lateral femoral condyle (LFC) length, LFC height, lateral tibial plateau (LTP) length, LTP slope and by calculating the following ratios LFC ratio (LFC length/LFC height), knee extension ratio (LFC length/LTP length), and knee flexion ratio (LFC height/LTP length). The status of the anterolateral ligament (ALL) was assessed by preoperative MRI scans and classified as completely injured (44 patients), partially injured (19 patients), or intact (4 patients). The ATT was compared between patients with completely injured ALL and those with partially injured or intact ALL. Pearson correlation analysis between the ATT and each bony variable was performed in ALL-completely-injured patients and ALL-partially-injured or intact patients.Results:Of the 67 patients, 33 were male and 34 were female, with a mean of age 31.7±9.7 years (range 15-47 years). The average of time interval between ACL injury and MRI examination was 26.0±22.0 days (95% CI 20.7, 31.4 d). The ATT of the lateral compartment was 5.6±4.0 mm (range, -4.9-16.2 mm), the average of LFC length was 37.3±2.5 mm (range, 30.5-43.2 mm), the average of LFC height was 37.4±3.6 mm (range, 30.6-46.3 mm), the average of LTP length was 46.9±4.1 mm (range, 39.0-56.8 mm), the average of LTP slope was 6.3°±3.1° (range, -3.7°-11.6°), LFC ratio was 100.4%±8.1% (range, 84.1%-119.0%), knee extension ratio was 80.0%±5.8% (range, 66.1%-96.3%), and knee flexion ratio was 80.0%±6.0% (range, 66.4%-93.8%). The ATT was greater in patients with completely injured ALL than in patients with partially injured or intact ALL (6.4±4.3 mm vs. 3.9±2.8 mm, t=2.52, P=0.014). The ATT was negatively correlated with LFC height ( r=-0.43, P<0.001) and LTP length ( r=-0.35, P=0.004) and was positively correlated with LFC ratio ( r=0.48, P<0.001), knee extension ratio ( r=0.36, P=0.003), and LTP slope ( r=0.29, P=0.018). All these correlations were still statistically significant in patients with complete ALL injury ( P<0.05), but were no significant in patients with partial ALL injury or intact ALL ( P>0.05). Conclusion:Bony morphology of the distal femur and proximal tibia was associated with ATT after ACL injury. Such an association was more dramatic in patients with a complete ALL injury.