Background
There is sparse evidence on how the treatment of concomitant medial collateral ligament (MCL) or lateral collateral ligament (LCL) injuries in the setting of an anterior cruciate ligament (ACL) rupture affects outcome after ACL reconstruction.
Purpose
To determine how concomitant MCL and LCL injuries affect outcome after ACL reconstruction.
Study Design:
Cohort study, Level III
Methods
Patients aged > 15 years who were registered in the Swedish National Knee Ligament Registry for primary ACL reconstruction between 2005 to 2016 were eligible for inclusion. One isolated ACL reconstruction group was created and six groups were stratified according to treatment of a concomitant MCL or LCL injury (non-surgical, repair or reconstruction). The outcomes were ACL revision and the two-year Knee Injury and Osteoarthritis Outcome Score (KOOS). Univariable and adjusted multivariable Cox regression were used to determine the proportional hazards of ACL revision, and the KOOS was compared using an analysis of covariance.
Results
A total of 19,457 patients (mean age 27.9 years, 59.4% males) met the inclusion criteria. An isolated ACL reconstruction implied a lower risk of ACL revision compared with presence of a non-surgically treated MCL injury (HR=0.61 [95% CI 0.41-0.89], p=0.0097), but not compared with MCL suture repair or reconstruction. The risk of ACL revision did not differ between isolated ACL reconstruction and patients with a concomitant LCL injury. A concomitant MCL or LCL injury was associated with a worse two-year KOOS compared with an isolated ACL injury. The largest difference was found in the sports and recreation subscale across all groups, with MCL reconstruction resulting in the largest difference (14.1 points [95% CI 4.3-23.9], p=0.005).
Conclusion
Non-surgical treatment of a concomitant MCL injury in the setting of an ACL reconstruction may increase the risk of ACL revision. However, surgical treatment of an MCL injury was associated with a worse two-year patient-reported knee function. A concomitant LCL injury does not impact the risk of ACL revision compared with an isolated ACL reconstruction.