Correlates of Knee laxity change in early rehabilitation after anterior cruciate ligament reconstruction

Factors other than ligament graft length (knee ROM, knee swelling, initial knee laxity) may need to be accounted for in interpreting changes in knee laxity during rehabilitation following anterior cruciate ligament reconstruction (ACLR) surgery. Twenty-three patients recovering from ACLR surgery (16 M, 7 F, age mean = 30) were tested at 2 and 6 weeks after ACLR with knee laxity measured using th Knee Signature System arthrometer, passive ROM with a standard goniometer and swelling by measuring knee circumference at the mid-patella level using a cloth measuring tape. Spearman correlation coefficients (in parentheses) were calculated using rankings of the change in the injured minus uninjured knee laxity as the dependent variable and the following independent variables: pre-test injured minus uninjured knee laxity (ranked; -0.457; statistically significant two-tailed P < 0.05); change in injured knee maximum extension relative to the uninjured side (ranked; 0.127); change in injured knee maximum flexion relative to the uninjured side (unranked; -0.073); and change in the injured minus uninjured knee girth (unranked; -0.159). These results indicate that consideration should be given to the patient's knee laxity at the start of intervention when using changes in laxity to guide rehabilitation after ACLR.