Nanohydroxyapatite promotes the healing process in open-wedge high tibial osteotomy. A CT study

Background The aim of this prospective and randomized study was to evaluate the effectiveness of adding nanohydroxyapatite (NHA) to heterologous bone graft in open wedge high tibial osteotomy (OWHTO) by measuring the bone density of the tibial osteotomy gap. Methods Twenty-seven patients (26 knees) were operated by OWHTO and randomly divided into two groups: pure graft group, in which the osteotomy gap was filled with only heterologous bone graft; nanohydroxyapatite group, in which the osteotomy gap was filled with heterologous bone graft and NHA. All patients underwent computed tomography (CT) examination within one week after operation (Time 0), and after two months (Time 1) and 12 months (Time 2). CT volume acquired Hounsfield Units (HU) were calculated and the mean value of bone density on three planes was measured. Results At Time 0, the mineral density of the nanohydroxyapatite group appeared significantly higher compared with the pure graft group, due to the presence of NHA. At Time 1, the mineral density of the nanohydroxyapatite group had decreased relative to Time 0, while in the pure graft group it remained unchanged. At Time 2, the mineral density in the nanohydroxyapatite group had further decreased, reaching values close to the mineral density of normal bone. In contrast, in the pure graft group the mineral density had increased, probably due to the lack of reabsorption of the graft and the development of sclerosis in the osteotomy borders. Conclusions The results of the present study show better osseointegration of the heterologous graft when nanohydroxyapatite is added.