Arthroscopic Lateral Tibial Plateau Translation Correlates With Pivot-Shift Severity in Anterior Cruciate Ligament-Deficient Knees.

Abstract

Purpose: To quantify arthroscopic lateral tibial plateau (LTP) translation in anterior cruciate ligament (ACL)-deficient knees using a standardized intraoperative protocol and to evaluate its association with pivot-shift grade and lateral tibial slope, including its ability to discriminate high-grade pivot-shift.

Methods: Patients aged 18 to 45 years with an isolated ACL rupture confirmed by clinical examination, magnetic resonance imaging, and arthroscopy who met the predefined eligibility criteria and had arthroscopic video of adequate quality for measurement underwent standardized arthroscopic assessment of LTP translation. Arthroscopic LTP translation was quantified from standardized high-definition arthroscopic video recordings using a calibrated probe during valgus and internal rotation stress at 30° of knee flexion. Measurements were independently repeated by 2 observers. Associations with preoperative pivot-shift grade and lateral tibial slope were assessed. Diagnostic performance was evaluated using receiver operating characteristic analysis.

Results: Sixty patients (38 men, 22 women; mean age 29.8 ± 6.7 years) were included in the final analysis. Mean arthroscopic LTP translation was 4.6 ± 1.7 mm (range, 2-8 mm). Reproducibility was excellent (intraclass correlation coefficient intra = 0.91; inter = 0.89). LTP translation strongly correlated with pivot-shift grade (r = 0.72, P < .001) and moderately with lateral tibial slope (r = 0.51, P = .003). Receiver operating characteristic analysis showed an area under the curve of 0.85 (95% confidence interval, 0.77-0.93). A threshold of >5 mm yielded 82% sensitivity and 78% specificity for detecting high-grade pivot-shift.

Conclusions: Arthroscopic quantification of LTP translation is a reproducible and clinically relevant method for objectively assessing rotational instability in ACL-deficient knees. Arthroscopic quantification of LTP translation showed excellent inter- and intraobserver reliability and was strongly associated with preoperative pivot-shift grade. A translation threshold greater than 5 mm showed good discriminative performance for identifying high-grade pivot-shift.

Level of evidence: Level III, retrospective comparative study.