Fifty-four patients with precollapse osteonecrosis of the femoral head (ONFH) were randomized to core decompression plus autologous osteoblastic cells (n=25) or core decompression plus placebo (n=29). The primary outcome was a composite 24-month “treatment response” (WOMAC pain improvement ≥10 mm and no radiographic progression to ≥ARCO III). Secondary outcomes included the same composite at 12 months, its clinical and radiologic components at 12 months, and THA by 24 months. Follow-up was 24 months. Overall, the results of the study revealed no between-group differences in the primary composite at 24 months and no differences at 12 months for the composite, clinical response, or radiologic response. THA occurred in 24% vs 14% with the numbers available. In short, adjunct osteoblastic cells did not enhance outcomes over core decompression alone, while adverse events were uncommon and generally mild.