Pivot-shift test: analysis and quantification of knee laxity parameters using a navigation system.

Lachman, drawer, and pivot-shift (PS) tests are important in the assessment of ACL reconstruction. The goal of this work was to analyze the reliability of the PS test using a navigation system, identifying a set of new quantitative parameters and evaluating their clinical relevance. Eighteen patients that underwent anatomic double-bundle ACL reconstruction were included. The new dynamic parameters were: anteroposterior translation of the medial and lateral compartments and the joint center and internal/external and varus/valgus rotations of the joint. For each parameter we measured the peaks and the areas obtained during the test. Intratester repeatability, comparisons of pre- and postoperative laxities, and correlations between the PS peaks and the corresponding peaks obtained with standard static tests were evaluated. Areas, peaks, and static laxity outcomes were compared, grouping patients according to the preoperative International Knee Documentation Committee (IKDC) score. The PS test was reliable in identifying the surgical reconstruction. Correlation analysis showed good coefficients both for pre- and postoperative values. Patients with IKDC grade "D" had larger areas during the PS compared to patients with grade "C". Our analysis is helpful for characterizing patient-specific laxity and surgical performance, thus highlighting the clinical relevance of the PS test.