Background: In patients with unicompartmental medial knee arthritis, medial opening wedge high tibial osteotomy is used to shift the mechanical weightbearing line laterally to reduce pain and improve function. There have been concerns that opening wedge high tibial osteotomy is associated with a reduction of patellar height and increase in the sagittal posterior tibial slope, both of which can adversely affect the final result.
Hypothesis: A more distal oblique osteotomy at the level of insertion of the patellar tendon should decrease these effects when compared with a horizontal osteotomy made proximal to the patellar tendon insertion.
Study design: Cohort study; Level of evidence, 3.
Methods: Review of 22 horizontal and 19 oblique high tibial osteotomies with a mean follow-up of 4.2 +/- 1.8 years (mean +/- SD) was performed. Anatomic tibiofemoral angle, mechanical weightbearing line, medial coronal tibial plateau angle, patellar height (Blackburne and Peel ratio), and sagittal tibial slope were measured.
Results: In both groups, the weightbearing line was equally shifted toward the center of the plateau. In the horizontal group, the Blackburne and Peel ratio decreased from 0.85 +/- 0.16 to 0.67 +/- 0.12, and the sagittal tibial slope was increased from 7.7 degrees +/- 4.6 degrees to 10.7 degrees +/- 3.8 degrees (P < .001). In comparison, the oblique group did not show any significant postoperative changes for these 2 parameters. In the oblique group, 2 patients sustained loss of correction and early failure when the osteotomy remained below the metaphyseal flare on the lateral cortex.
Conclusion: The oblique osteotomy group showed more normalized postoperative sagittal tibial slope and patellar height. Caution should be exercised not to osteotomize too distally.