Posteromedial Open-Wedge High Tibial Osteotomy to Avoid Posterior Tibial Slope Increase.

PURPOSE

The primary aim was to evaluate the influence of the surgical modification on posterior tibial slope (PTS) and patellar height in open-wedge high tibial osteotomy (OWHTO). The secondary aim was to evaluate the influence of preoperative mechanical axis deviations (MA) on PTS METHODS: Between January 2014 and February 2016, patients with a diagnosis of medial-compartment osteoarthritis who had undergone OWHTO with posteromedial osteotomy technique with a minimum follow-up of 3 months were included in this retrospective study. Preoperative and postoperative PTS angles with 3 different methods and patellar heights with respect to the Insall-Salvati and Caton-Deschamps indices were measured on lateral radiographs by 2 observers. Patients were grouped according to preoperative MA (either <10° or ≥10°). PTS changes were compared between groups RESULTS: Thirty consecutive knees of 28 patients were evaluated. Preoperative mean PTS angles were 9.50° ± 4.47° (posterior tibial cortex referenced), 11.51° ± 4.50° (tibial anatomical axis referenced), and 10.80° ± 4.58° (posterior fibular cortex referenced); postoperative angles were 6.10° ± 4.23°, 8.78° ± 4.57°, and 8.11° ± 4.55°, respectively. PTS was significantly decreased postoperatively with respect to all 3 methods (P < .0001). Mean preoperative and postoperative Insall-Salvati indices were 1.04 ± 0.16 and 1.07 ± 0.17, respectively (P = .088). Mean preoperative and postoperative Caton-Deschamps indices were 0.87 ± 0.18 and 0.78 ± 0.18, respectively (P = .017). PTS changes were not statistically significant between groups with respect to MA (P values .861, .723, and .727, respectively) CONCLUSIONS: It is possible to preserve and even decrease PTS with an OWHTO performed posterior to MCL in a posteromedial to anterolateral direction.

LEVEL OF EVIDENCE

Level IV, retrospective case series.