Prognosis after autologous peripheral blood stem cell transplantation for osteonecrosis of the femoral head in the pre-collapse stage: a retrospective cohort study.

Objectives: Autologous peripheral blood stem cell (auto-PBSC) transplantation is an effective therapeutic for the osteonecrosis of the femoral head (ONFH) but without prognosis estimation. This study mainly aimed to (1) determine whether auto-PBSC transplantation is a promising option, (2) assess the risk of hip-preservation failure, (3) achieve a predictive model of femoral head survival after the intervention, and (4) eventually identify clinical indications for auto-PBSC transplantation in future.

Methods: After reviewing the in-patient database of the First Affiliated Hospital of Zhejiang Chinese Medicine University from June 2012 to June 2014, 37 eligible patients with Association Research Circulation Osseous stage I or II ONFH who were receiving intra-arterial infusion of auto-PBSCs were recruited. A case form was designed to retrieve relevant data. Hip-preservation failure was defined as the endpoint. All participants were stratified by the categorical risk of collapse, which was statistically tested through log-rank analysis. All significant factors were evaluated using Cox proportional hazards regression model, and a predictive nomogram plot was generated.

Results: In total, 47 hips were followed up for 53.96 ± 21.09 months; the median survival time was 60.18 months. Among the predictors, body mass index (BMI; P = 0.0015) and Harris hip score (HHS; P < 0.0001) independently affected femoral head survival. Patients with BMI ≥ 24 kg/m exhibited a 2.58 times higher risk of hip-preservation failure [95% confidence interval (CI), 1.32-5.45] than those with BMI < 24 kg/m, whereas those with HHS ≥ 70 exhibited a 0.19 times lower risk (95% CI, 0.09-0.38) than those with HHS < 70. Hazard ratios associated with age (P = 0.042), BMI (P = 0.012), HHS (P = 0.022), and necrotic volume (P = 0.000) were 1.038 (95% CI, 1.001-1.075), 1.379 (95% CI, 1.072-1.773), 0.961 (95% CI, 0.928-0.994), and 1.258 (95% CI, 1.120-1.412), respectively. A nomogram plot (score test P = 0.000; C-index = 0.8863) was available for the orthopedic doctor to predict hip survival probability.

Conclusions: The results suggest that intra-arterial infusion of auto-PBSCs prolongs femoral head survival. Age, BMI, HHS, and necrotic volume can influence the efficacy of this intervention. This study was approved by ethics committee of the trial center, number 2019-KL-075-01.