Preoperative Knee Instability Affects Residual Instability as Evaluated by Quantitative Pivot-Shift Measurements...

Area of Science:

• Orthopedic surgery
• Biomechanical analysis
• Sports medicine

Background:

• The pivot-shift test is crucial for assessing functional outcomes post-anterior cruciate ligament reconstruction (ACLR).
• Preoperative knee instability, identified by the pivot-shift test, correlates with persistent instability after ACLR.
• Quantitative evaluation of the pivot shift after ACLR remains understudied.

Purpose of the Study:

• To examine the link between preoperative and residual knee instability.
• To identify risk factors for residual instability using quantitative pivot-shift measurements.
• To investigate the predictive value of preoperative instability on intraoperative findings.

Main Methods:

• A retrospective case-control study involving 91 patients undergoing primary double-bundle ACLR.
• Quantitative pivot-shift testing with inertial sensors to measure acceleration and external rotation (ER) angular velocity in ACL-deficient (ACLD) and ACLR knees.
• Comparison of instability ratios (ACLD/intact and ACLR/intact) to classify patients into residual instability or non-instability groups.

Main Results:

• Preoperative instability (ACLD/intact ratio) for acceleration (OR, 1.6) and ER angular velocity (OR, 1.9) were significant predictors of intraoperative residual instability.
• Female sex was associated with lower odds of residual instability (OR, 0.3).
• Moderate correlations were found between preoperative and intraoperative instability measurements (r = 0.435 for acceleration, r = 0.533 for ER angular velocity).

Conclusions:

• Elevated preoperative instability is a key risk factor for residual instability following ACL reconstruction, as quantified by the pivot-shift test.
• Intraoperative quantitative pivot-shift analysis can potentially predict postoperative residual instability.
• This quantitative approach offers valuable insights for surgical planning and patient management in ACLR.