Infratuberosity osteotomies require greater wedge resection and result in increased cortical mismatch compared to supratuberosity: A morphometric study supporting individualized planning in posterior tibial slope correction.

Purpose: Posterior tibial slope (PTS) reducing anterior closing wedge osteotomies are increasingly used to address the elevated risk of anterior cruciate ligament (ACL) graft failure in patients with increased PTS. This study evaluates the wedge height required at two osteotomy levels-supratuberosity and infratuberosity-for equivalent PTS correction and examines its relationship with tibial anatomy.

Methods: Fifty patients undergoing multiple revision ACL reconstruction (ACL-R) with PTS ≥ 12° were retrospectively analyzed using standardized lateral knee radiographs. Simulated osteotomies at supratuberosity and infratuberosity levels were performed using MATLAB. Wedge thickness per degree, anterior cortical step-off, defined as the mismatch or offset between the anterior cortices of the proximal and distal tibial fragments following wedge removal, and tibial anterior-posterior width were measured. Correlations were assessed using Pearson's r. Model fit was evaluated with the coefficient of determination (R²), standard error of the estimate and root mean square error. Levene's test compared residual variance. A p value of <0.05 was considered statistically significant.

Results: The mean PTS was 14.6 ± 2.5°. Infratuberosity osteotomies required 1.2 ± 0.2 mm per degree correction versus 1 ± 0.1 mm for supratuberosity (p < 0.01). Cortical step-off was greater at the infratuberosity than the supratuberosity level (4.4 ± 1.6 mm vs. 1.8 ± 1.3 mm, respectively, p < 0.01). Tibial width strongly predicted wedge thickness at the supratuberosity level (r = 0.83, R² = 0.69), and moderately at the infratuberosity level (r = 0.66, R² = 0.48). Residual variance was not significantly different (p = 0.147).

Conclusion: Infratuberosity anterior closing wedge osteotomy (ACWO) requires significantly greater wedge resection and leads to a larger mismatch at the anterior tibial cortex compared to supratuberosity ACWO for the same amount of PTS correction. Considerable variability existed regarding tibial morphology at both levels. These results highlight the importance of patient-specific, anatomy-based planning when performing ACWO in the setting of revision ACL-R.

Level of evidence: Level IV.