Clinical outcomes and risk factors for failure of nano-hydroxyapatite/polyamide 66 bracing rod combined with allogeneic bone in treatment of early-stage osteonecrosis of the femoral head

PurposeThis study was performed to analyse the clinical factors associated with failure of nano-hydroxyapatite/polyamide 66 (nHA/PA66) bracing rods combined with allogeneic bone in the treatment of early-stage osteonecrosis of the femoral head (ONFH).MethodsIn total, 96 patients were treated with nHA/PA66 bracing rods combined with allogeneic bone for ONFH between October 2016 and September 2020. The patients were classified according to aetiology, Association Research Circulation Osseous (ARCO) type, Japanese Investigation Committee (JIC) type, age, and body mass index(BMI). The outcome measures were the Hip Harris Score (HHS), imaging changes, and the need for total hip arthroplasty (THA) (performed in cases of clinical failure, at which point follow-up was discontinued).ResultsAll patients were included in the study, with a mean follow-up duration of 50.76 +/- 17.94 months. The preoperative HHS was 79.00 +/- 13.61 and that at the final follow-up was 81.73 +/- 17.67(P = 0.149). The excellent and good rate improved from 43.88% preoperatively to 65.47% at the final follow-up(P = 0.000). The radiographic progression rate was 36.70% and the incidence of THA was 23.02%. Univariate analysis identified ARCO type (P = 0.000), JIC type (P = 0.000), and age (P = 0.003) as independent risk factors for postoperative failure. Postoperative multivariate analysis also confirmed ARCO type, JIC classification, and age as risk factors.ConclusionThis technique is not recommended for patients older than 44 years or those with ARCO type 3 or JIC type C ONFH.