The Efficacy of Bisphosphonates with Core Decompression and Mesenchymal Stem Cells Compared with Bisphosphonates Alone in the Treatment of Osteonecrosis of the Hip: a Retrospective Study.

INTRODUCTION: Osteonecrosis of the femoral head (ONFH) is a devastating disease with complete collapse of the femoral head often reported in greater than 70% of patients within 3 to 4 years of diagnosis. Early intervention prior to collapse may improve the chance of success of joint preserving procedures.

QUESTIONS/PURPOSES: The purpose of this study was to evaluate whether core decompression with mesenchymal stem cells combined with bisphosphonate therapy can improve the clinical outcomes and reduce the risk of hip replacement when compared to treatment with bisphosphonate therapy alone.

METHODS: Between 2006 and 2014, 84 consecutive patients who were diagnosed with ONFH were identified from our institution's registry. Of these 84 patients, 49 patients (62 hips), fit inclusion/exclusion criteria. Twenty-nine patients (40 hips) were treated with bisphosphonate therapy only. Twenty patients (20 hips) were treated with bisphosphonates, core decompression, and mesenchymal stem cells. Functional outcomes were assessed using the Modified Harris Hip Score (MHHS), the visual analog score (VAS), and evaluation of support system. Clinical failure was defined as deterioration of the MHHS/VAS scores and support system used severe enough to require THR. Radiologic outcome measures included the XR and MR imaging staging of the hip. Survival analysis was performed with total hip replacement as the end point failure. Collapse was defined as progression from Ficat stage I or II to stage III and from Steinberg I, II, III to IV, V, VI.

RESULTS: Failure requiring THR occurred in 21/40 (52.5%) of bisphosphonates (BP)-treated hips at a mean follow-up of 25.3 ± 11.5 months and 5/22 (22.73%) of BP + CD + MSC-treated hips at a mean follow-up of 22.7 ± 19.5 months. The median (Q1, Q3) time to collapse was 24.9 (7.4, 33.0) months in BP-treated hips and 27.3 (27.3) months in BP + CD + MSC-treated hips. There was no evidence of a difference in functional outcomes between the two treatment groups. After adjusting for baseline Ficat stage, age, and sex, an unreplaced hip treated with BP + CD + MSC had 0.42 (95% CI 0.11, 1.57) times the risk of being replaced in the next moment compared to an unreplaced hip treated with bisphosphonates only (P = 0.196).

CONCLUSION: Our results demonstrate that treatment with BP alone or BP + CD + MSC can postpone the need for total hip arthroplasty (THA) in the first 24 months in patients with ONFH compared to previously reported data, but there is no statistically significant difference between the two treatment groups. Combination therapy of BP + CD + MSC may be more effective in delaying the progression of collapse in early stage ONFH. Future prospective studies are warranted to determine the efficacy of these treatment strategies in the long term.