Anteromedial Gap Opening and Osteotomy Sufficiency Are Associated With Multiplanar Correction Errors in Open‐Wedge High Tibial Osteotomy: A Computed Tomography‐Based Study

PURPOSE: To evaluate 3-dimensional correction errors in the coronal, sagittal, and axial planes using computed tomography and identify surgical and anatomical factors associated with multiplanar correction errors after open-wedge high tibial osteotomy. METHODS: This retrospective study included patients who underwent biplanar open-wedge high tibial osteotomy between September 2014 and October 2022. The opening-angle error, posterior tibial slope (PTS) change, and axial rotation were measured using preoperative and 1- to 2-week postoperative computed tomography images; hinge angle and osteotomy sufficiency were evaluated. Analysis involved mixed-effects models adjusted for age, sex, and body mass index. RESULTS: Of 110 included knees (94 patients), the mean opening-angle error, PTS increase, and internal rotation were -0.1°, 2.6°, and 2.7°, respectively. Planned opening angle was associated with coronal undercorrection (β = 0.230, P = .001) and internal rotation (β = 0.321, P = .001); hinge angle with coronal undercorrection (β = 0.023, P = .039) and PTS increase (β = 0.045, P = .044); and osteotomy sufficiency was associated with a smaller PTS increase (β = -0.039, P = .005) but greater internal rotation (β = 0.046, P < .001). Sex-stratified analyses identified factors associated with correction errors: planned opening angle in both sexes; hinge angle, biplanar and sagittal osteotomy angles, and osteotomy sufficiency in women; and entry height and osteotomy sufficiency in men. Each degree of internal rotation was associated with a 1.6-point lower 1-year Lysholm score (β = -1.572, P = .018). Lateral hinge fractures occurred in 23.6% of knees. Type I fractures exhibited greater internal rotation, and type III fractures showed greater PTS increases and reduced postoperative flexion. CONCLUSIONS: Anteromedial gap opening was associated with coronal undercorrection and increased PTS during open-wedge high tibial osteotomy. Greater osteotomy sufficiency was associated with a reduced PTS increase but greater distal tibial internal rotation. Greater internal rotation was associated with lower 1-year Lysholm scores. LEVEL OF EVIDENCE: Level III, retrospective case-control study.