103 Investigating Whether Coronal Alignment Changes at the Knee Joint After Medial Opening Wedge High Tibial Osteotomy Influences the Coronal Alignment Changes at the Hip Joint

Abstract

Abstract Aim High tibial osteotomy (HTO) is used as an effective treatment for varus knee osteoarthritis (OA). However, the biomechanical relationship between the hip and knee is important. An observation was made by the senior author of this paper that patients reported a change in their hip function after a medial opening wedge high tibial osteotomy (MOWHTO). The effect of a MOWHTO on the hip joint has not been well documented. Therefore, we analysed coronal alignment changes at the hip after MOWHTO. Method We retrospectively analysed lower limbs imaging of patients who underwent MOWHTO for varus OA. Pre-operative and follow up standing bilateral full leg length anteroposterior radiographs were taken. The medial proximal tibial angle (MPTA) and mechanical axis deviation (MAD) were measured to assess the coronal alignment of the knee. The coronal alignment of the hip was evaluated using the mechanical greater trochanter angle (MGTA). Results After exclusion criteria were applied 31 osteotomies in 29 patients were included in this study. A positive correlation between the changes in MPTA and MAD with MGTA were found. The change in the MGTA had a stronger correlation with the MAD than with the change in MPTA (r = 0.749 vs 0.589). It was found that age, weight, height, and BMI had little influence on these correlations. Conclusions Increased correction by the MOWHTO lead to increased change in the MGTA at the hip. These changes are likely to result in an alteration in the weight bearing portion of the femoral head and the function of the abductors.