The Effect of Mild Residual Rotational Laxity on Performance After Anterior Cruciate Ligament Reconstruction.

Background: Some patients still experience mild residual rotational laxity of the knee after anterior cruciate ligament reconstruction (ACLR). The clinical symptoms of this residual rotational laxity are controversial, and methods for evaluating the symptoms have become a focus of academic interest in recent years. It is unclear whether there is a correlation between mild residual rotational laxity after ACLR and performance.

Purpose: To investigate the influence of residual mild rotational laxity after ACLR on subjective outcomes, performance, psychological readiness, and return to sports (RTS).

Study design: Cross-sectional study; Level of evidence, 3.

Methods: A total of 81 patients who underwent ACLR at our sports medicine center were observed for >2 years. The follow-up included KT-2000 measurements, the pivot shift test (PST), subjective outcome scores (Lysholm, International Knee Documentation Committee Subjective Knee [IKDC], Knee injury and Osteoarthritis Outcome Score [KOOS], ACL-Return to Sport after Injury Score [ACL-RSI], Tegner score, and Marx score), and performance evaluations, such as isokinetic testing at 60 deg/sec, hop tests, and Y-balance tests (YBT). Patients were grouped based on the results of the last PST follow-up on the operated knee. The stable group (SG) consisted of 42 patients with negative PST results, while the mild rotational laxity group (MIG) comprised 39 patients with PST grade 1. Statistical analysis was conducted to compare patient characteristics, subjective outcome scores, and performance between the 2 groups.

Results: Significant differences were observed between the 2 groups in the single-leg hop test, the triple hop test, and the cross-over hop limb symmetry index, respectively (P = .013; P = .017; P = .046). In addition, the SG had significantly higher ACL-RSI scores than the MIG (69.54 ± 21.34 vs 53.60 ± 21.66; P = .006); and postoperative Tegner scores were significantly higher in the SG compared with the MIG (5.81±1.70 vs 4.95 ± 1.93; P = .036). No significant differences were observed in Lysholm, IKDC, KOOS score, postoperative Marx, or KT-2000 side-to-side difference scores, and no significant differences were found in isokinetic testing at 60 deg/sec, hamstring-to-quadriceps ratio, or YBT results between the 2 groups.

Conclusion: Residual mild rotational laxity in the knee after ACLR leads to poorer performance in hop tests and a lower level of activity, and poor psychological readiness. Furthermore, in short- to medium-term follow-up after ACLR, regardless of knee rotational laxity, the return to preinjury activity rate remains low, with the majority not meeting the safe RTS criteria.