The role of “cell therapy” in osteonecrosis of the femoral head A systematic review of the literature and meta-analysis of 7 studies

Background and purpose — The value of core decrompression for treatment of osteonecrosis of the femoral head (ONFH) is unclear. We investigated by a literature review whether implan- tation of autologous bone marrow aspirate, containing high con- centrations of pluripotent mesenchymal stem cells, into the core decompression track would improve the clinical and radiological results compared with the classical method of core decompression alone. The primary outcomes of interest were structural failure (collapse) of the femoral head and conversion to total hip replace- ment (THR). Patients and methods — All randomized and non-randomized control trials comparing simple core decompression with autolo- gous bone marrow cell implantation into the femoral head for the treatment of ONFH were considered eligible for inclusion. The methodological quality of the studies included was assessed inde- pendently by 2 reviewers using the Cochrane Collaboration tool for assessing risk of bias in randomized studies. Of 496 relevant citations identified, 7 studies formed the basis of this review. Results — The pooled estimate of effect size for structural fail- ure of the femoral head favored the cell therapy group, as, in this treatment group, the odds of progression of the femoral head to the collapse stage were reduced by a factor of 5 compared to the CD group (odds ratio (OR) = 0.2, 95% CI: 0.08–0.6; p = 0.02). The respective summarized estimate of effect size yielded halved odds for conversion to THR in the cell therapy group compared to CD group (OR = 0.6, 95% CI: 0.3–1.02; p = 0.06). Interpretation — Our findings suggest that implantation of autologous mesenchymal stem cells (MSCs) into the core decom- pression track, particularly when employed at early (pre-col- lapse) stages of ONFH, would improve the survivorship of femo- ral heads and reduce the need for hip arthroplasty.