Retro-tubercular Biplanar Medial Opening-Wedge High Tibial Osteotomy Results in Superior Patellofemoral Alignment Versus Supra-tubercular Osteotomy.

PURPOSE

To compare the changes in patellofemoral (PF) joint alignment, focusing on multiple planes, between two different types of biplanar medial opening-wedge high tibial osteotomy (OWHTO).

METHODS

Patients who underwent biplanar OWHTO between July 2017 and May 2021 were retrospectively evaluated. They were allocated to either the supra-tubercular (ST)- or retro-tubercular (RT)-OWHTO group. The following radiologic parameters were compared between the two groups: 1) weight-bearing line ratio (WBLR), 2) patellar height, 3) posterior tibial slope (PTS), 4) tibial tubercle-trochlear groove (TT-TG) distance, 5) TT-TG angle, and 6) femoral shaft-patellar tendon (FS-PT) angle. Clinical outcomes and the minimal clinically important difference (MCID) were also evaluated.

RESULTS

In total, 104 knees that underwent ST-OWHTO and 105 knees that underwent RT-OWHTO were evaluated. The patellar height significantly decreased only after ST-OWHTO (P < .001). The TT-TG distance and FS-PT angle significantly increased, more after ST-OWHTO than RT-OWHTO (mean change value: 5.72 mm vs 1.91 mm; P < .001 for TT-TG distance; and 4.72° vs 1.80°; P < .001 for FS-PT angle). The TT-TG angle increased significantly after ST-OWHTO (mean change value: 7.62°; P < .001) but decreased after RT-OWHTO mean change value: -4.30°; P < .001). The PTS more increased after RT-OWHTO than after ST-OWHTO (mean change value: 0.91° vs 1.69°; P = .003). Clinical outcomes in both groups improved postoperatively, and no significant differences were observed between the groups.

CONCLUSIONS

RT-OWHTO resulted in lesser changes in multiplane PF joint alignment than ST-OWHTO. However, no difference was observed in clinical outcomes between both groups, and PTS increased after RT-OWHTO. Therefore, these aspects of RT-OWHTO should also be considered.

LEVEL OF EVIDENCE

Level III, retrospective cohort study.