Mid-term CT assessment of bone healing after nanohydroxyapatite augmentation in open-wedge high tibial osteotomy

The aim of the present study was to confirm the effectiveness of adding nanohydroxyapatite (NHA) to a heterologous bone graft in open-wedge high tibial osteotomy (OWHTO) by measuring the bone density via multislice computed tomography (CT) of the tibial osteotomy gap in a mid-term follow-up (five years).Twenty-six patients undergoing OWHTO were randomly assigned to two groups: a pure graft group (Group A), in which the osteotomy gap was filled with only heterologous bone graft, and an NHA group (Group B), in which the osteotomy gap was filled with heterologous bone graft and NHA. CT was performed within one week of the operation, after two months, after 12 months and after five years. CT volume acquired in Hounsfield units (HU) was measured on three planes.The normal bone density was 110.2 ± 11.7 HU. The value of mean density at five years in Group A was 296.8 ± 81.8 HU, while in Group B, it was 202.2 ± 45.1 HU, showing a density more similar to normal bone and greater bone uniformity inside the osteotomy. The difference between the two groups was statistically significant (p 0.05). Furthermore, both groups showed excellent mid-term clinical outcomes without significant differences.This study revealed that absorbability and bone formation at the osteotomy site in the NHA group was significantly higher as compared with the pure graft group at five years postoperatively.