Presence of post-operative IKDC B Lachman or pivot-shift does not impact patient-reported outcome scores 2 years following ACL reconstruction
While a primary goal of anterior cruciate ligament reconstruction is to reduce pathologically increased anterior and rotational laxity of the knee, the relationship between degree of knee laxity after ACLR and patient-reported knee function remains clear. The goal of this study is to evaluate the relationship between the degree of knee laxity and patient-reported outcomes in a cohort of young patients injured in sports without graft tear or contralateral ACL tear 2 years following primary ACL reconstruction. We hypothesized that there would be no significant correlation between the degree of anterior and rotational knee laxity and patient-reported outcomes.
From a prospective multi-center cohort of patients, 433 patients under age 35 years injured in sports with no history of concomitant ligament surgery, revision ACL surgery, or surgery of the contralateral knee were identified at a minimum 2 years following primary ACL reconstruction and evaluated. These patients underwent physical examination by an independent examiner that included Lachman and pivot-shift evaluation as well as a KT-1000 assessment of anterior knee laxity and measurement of range of motion with a goniometer. Patients also completed patient-reported outcome assessments with KOOS and IKDC scores. A proportional odds logistic regression model to predict each patient-reported outcome score that included pre-op score, age, BMI, smoking status, Marx activity score, sex, level of education, whether they had additional surgery following ACLR, meniscus and cartilage status, graft type, and range of motion asymmetry was created. Measures of knee laxity (Lachman, pivot-shift, and KT-1000) were independently added to each model to determine whether these measures of laxity correlated with patient-reported outcomes.
Side to side manual Lachman differences were IKDC A (0-2mm) in 246 patients, IKDC B (2-6 mm) in 183 patients, and IKDC C (6-10 mm) in 4 patients. Pivot-shift was classified as IKDC A in 209 patients, IKDC B in 183 patients, and IKDC C in 11 patients. Patients with IKDC B Lachman were noted to have significantly increased KOOS-Sport/Rec scores compared to those with IKDC A Lachman (p = 0.031). Lachman grade did not correlate with any other patient-reported outcome measure. There were no significant correlations noted between pivot-shit or tibial translation as assessed by KT-1000 and any patient-reported outcome. All predicted differences in patient-reported outcome scores based on IKDC A versus B pivot-shift and anterior tibial translation were less than 4 points.
Discussion And Conclusion
Neither the presence of IKDC A versus B pivot-shift nor increased anterior tibial translation of up to 6 mm compared to the contralateral side are associated with poorer patient-reported outcomes 2 year following ACL reconstruction