Association between clinical symptoms and lateral thrust 12 months after high tibial osteotomy

[Purpose] This study aimed to assess the correlation between lateral thrust and clinical symptoms after high tibial osteotomy and determine lower limb alignments that may decrease lateral thrust. [Participants and Methods] We included 54 patients (73 knees) who underwent high tibial osteotomy. Clinical symptoms, including the Japanese Orthopaedic Association score and the hip-knee-ankle angle measured via radiography, were assessed 12 months postoperatively. Lateral thrust was measured using three-dimensional motion analyses. Logistic regression was used to calculate the cut-off values with good Japanese Orthopaedic Association score and lateral thrust as dependent variables and both lateral thrust and hip-knee-ankle angle as independent variables. [Results] The lateral thrust cut-off was 3.1° (sensitivity: 0.83; specificity: 0.74; area under the curve: 0.76), while that of the hip-knee-ankle angle was 1.9° of valgus (sensitivity: 0.71; specificity: 0.81; area under the curve: 0.72). [Conclusion] Good clinical outcomes after high tibial osteotomy can be expected with a lateral thrust of ≤3.0°, indicating that the target hip-knee-ankle angle should be 2.0° valgus. In cases where valgus alignment is insufficient, lateral thrust may develop, which should be assessed using gait analysis.