Changes in Flexion and Extension Gaps After Tibial Tubercle Osteotomy and Quadriceps Snip During Total Knee Arthroplasty: A Sequential Cadaveric Study

Abstract

Purpose: Quadriceps snip (QS) and tibial tubercle osteotomy (TTO) are extensile exposure techniques used during revision total knee arthroplasty (TKA) and complex primary TKA. We evaluated whether QS and TTO alter intraoperative flexion and extension gaps in a cadaveric TKA model.

Methods: Six fresh cadaveric knees from three cadavers underwent medial parapatellar exposure and standardized bone resection. The flexion gap at 90° and extension gap at 0° were measured using a tensioning device applying 40 lb (178 N) of force. TTO was performed, and both gaps were remeasured. The tibial tubercle was anatomically fixed, after which QS was performed and the measurements were repeated. This was a sequential within-specimen design with a fixed procedural order. Changes after TTO and QS were compared using paired t-tests.

Results: Mean true flexion and extension gaps were 13.24 ± 3.06 mm and 9.47 ± 1.52 mm, respectively. TTO increased the flexion gap by 3.64 ± 1.48 mm, whereas QS increased it by 1.50 ± 1.13 mm. The mean difference in flexion-gap change was significant (2.14 mm; 95% CI, 0.89 to 3.38; P = 0.007). Extension-gap changes were small: 0.79 ± 1.20 mm after TTO and 0.20 ± 0.67 mm after QS, without a significant difference (0.59 mm; 95% CI, −0.41 to 1.60; P = 0.190).

Conclusions: In this sequential cadaveric TKA model, TTO produced a greater flexion-gap increase than the subsequent QS stage, whereas no significant difference in extension-gap change was detected. The fixed procedural sequence should be considered when interpreting these exploratory findings.