Abstract
Introduction and Objectives:
Anterior cruciate ligament (ACL) injury is one of the most common knee injuries in sport activities. Diagnosis of ACL injury relies on examining primary and secondary signs through magnetic resonance imaging (MRI) and definitively through arthroscopy. Anterior translation of the tibia (ATT) of ≧7 mm has been an established secondary sign of ACL injury visualised in MRI. Furthermore, patellar malalignment was associated with ACL injury which can be detected through several patellar height measurements. The present study aimed to examine the differences in patellar height measurements between ACL insufficient knees with ATT ≧7 mm and <7 mm, and the association between ATT and patellar height measurements.
Materials and Methods:
A total of 133 study participants with ACL injury were included in this study. Study participants were examined clinically and radiologically. Furthermore, all study participants underwent arthroscopic ACL reconstruction surgery. Age, gender, and BMI were recorded during admission. All study participants underwent MRI scan to assess ATT and patellar height measurements which include Insall-Salvati ratio, Modified Insall-Salvati ratio, Caton-Deschamps index, and Blackburne-Peel ratio. Independent sample T-test was carried out to compare parameters between ATT values. Linear regression was done to examine the association between ATT and patellar height measurements.
Results:
There were significant differences between those with ≧7 mm and <7 mm of ATT in patellar tendon length [42.14 (4.95) vs 43.98 (5.33), p=0.045] and Insall-Salvati ratio [1.04 (0.16) vs 1.11 (0.16), p=0.017]. Every increase in ATT was negatively associated with Insall-Salvati ratio (regression coefficient -5.71, 95%CI -8.67, -2.75, p<0.001) and Caton-Deschamps index (regression coefficient -2.90, 95%CI -5.75, -0.04, p=0.047) after adjusting to age, sex, and BMI.
Conclusion:
Greater anterior translation of the tibia was associated with a reduction in Insall-Salvati ratio and Caton-Deschamps index. Lower value of patellar tendon length and Insall-Salvati ratio was observed in subjects with ATT ≧7 mm. The findings in this study signify the role of ACL injury in demonstrating patellar malalignment secondary to increased ATT.