Summary
This retrospective study aimed to identify the risk factors of abnormal knee laxity after anatomical ACL reconstruction. The study analyzed data from 291 patients who underwent ACL reconstruction and found that higher initial graft tension protocol, chronicity of ACL deficiency, and lateral meniscus resection were the risk factors for abnormal knee laxity after anatomical ACL reconstruction.
Abstract
Purpose
Graft failure or recurrence of instability without obvious trauma remains one of the problems after anterior cruciate ligament (ACL) reconstruction. This retrospective study aimed to identify the risk factors of abnormal knee laxity after anatomical ACL reconstruction.
Methods
A total of 291 patients who underwent primary anatomical ACL reconstruction and whose complete perioperative data records were available for follow-up for =24 months after the operation were included in this study. Gender, age, body mass index (BMI), time to surgery, medial meniscal status, lateral meniscal status, graft materials, initial graft tension, and preoperative and postoperative side-to-side differences in anterior tibial translation using the arthrometer were reviewed. Abnormal knee laxity was defined as constituting one or both of the following criteria: (1) a side-to-side difference of =3 mm on arthrometer, and (2) a positive pivot-shift test, being “glide,” “clunk,” or “gross”.
Results
Abnormal knee laxity occurred in 30 patients (10.3%) at a median follow-up of 25 months. Nineteen patients (6.5%) showed a side-to-side difference of =3 mm by arthrometer. A total of 21 patients (7.2%) showed a positive pivot shift test, of whom 19 were graded as glide and 2 as clunk; there was no patient graded as gross. Results of the univariate analysis indicated that a higher likelihood of abnormal knee laxity was associated with female, greater BMI, longer time to surgery, higher initial graft tension protocol, and lateral meniscus resection. No significant difference was observed between the stable and unstable groups in terms of mean age at ACL reconstruction, graft material, preoperative laxity, and medial meniscus. The result of subanalysis revealed that ACL reconstruction using hamstring tendon graft was more susceptible to the effects of the initial graft tension protocol. The multivariate logistic regression analysis showed that abnormal knee laxity was significantly associated with time to surgery (1-month increase; odds ratio (OR), 1.01), higher initial graft tension protocol (vs. lower tension; OR, 3.5), and lateral meniscus resection (vs. intact and repaired lateral meniscus; OR, 12.8).
Conclusion
Higher initial graft tension protocol, chronicity of ACL deficiency, and lateral meniscus resection were the risk factors for abnormal knee laxity after anatomical ACL reconstruction.