Improvements in spinal alignment after high tibial osteotomy in patients with medial compartment knee osteoarthritis

•Pre- and post-operative spinal alignment parameters were compared.•All spinal alignment parameters after HTO were closer to those of healthy controls.•HTO had a positive effect on spinal alignment as well as lower extremity alignment.•HTO reduced abnormality that may result in spinal problems such as degeneration.

Since the correlation between spinal and lower extremity alignments is high, high tibial osteotomy (HTO) surgery may also affect spinal alignment, where the spinal alignment parameters are the most important parameters for the evaluation of spinal disorders. In this study, the effect of HTO surgery on spinal alignment during gait was investigated by comparing spinal alignment parameters between patients with knee osteoarthritis (OA) and healthy young controls. Eight patients (age, 55.0 ± 5.1 years; height, 160.3 ± 7.0 cm; weight, 71.3 ± 14.1 kg) with a medial compartment knee OA participated in the gait experiment two times approximately one week before and one year after HTO surgery and eight healthy young controls (age, 26.7 ± 1.7 years; height, 163.4 ± 6.5 cm; weight, 58.4 ± 11.3 kg) participated only once. Cervical curvature angle, thoracic curvature angle, lumbar curvature angle, coronal vertical axis, and coronal pelvic tilt in the coronal plane and cervical lordosis, thoracic kyphosis, lumbar lordosis, sagittal vertical axis, and sagittal pelvic tilt in the sagittal plane were estimated using motion analysis system with skin markers. All spinal alignment parameters after HTO surgery were significantly closer to those of healthy young subjects than those before HTO, especially in the coronal plane. These findings suggest that the HTO had a positive effect on spinal alignment, as well as lower extremity alignment, and moreover, reduced the abnormality that may result in spinal problems such as degeneration or pain.