Quantitative assessment of the yield of osteoblastic connective tissue progenitors in bone marrow aspirate from the iliac crest, tibia, and calcaneus.

BACKGROUND: It is well known that bone marrow aspirate from the iliac crest contains osteoblastic connective tissue progenitor cells. Alternative harvest sites in foot and ankle surgery include the distal aspect of the tibia and the calcaneus. To our knowledge, no previous studies have characterized the quality of bone marrow aspirate obtained from these alternative sites and compared the results with those of aspirate from the iliac crest. The goal of this study was to determine which anatomic location yields the highest number of osteoblastic progenitor cells.

METHODS: Forty patients were prospectively enrolled in the study, and separate bone marrow aspirate samples were harvested from the ipsilateral anterior iliac crest, distal tibial metaphysis, and calcaneal body. The aspirate was centrifuged to obtain a concentrate of nucleated cells, which were plated and grown in cell culture. Colonies that stained positive for alkaline phosphatase were counted to estimate the number of osteoblastic progenitor cells in the initial sample. The anatomic locations were compared. Clinical parameters (including sex, age, tobacco use, body mass index, and diabetes) were assessed as possible predictors of osteoblastic progenitor cell yield.

RESULTS: Osteoblastic progenitor cells were found at each anatomic location. Bone marrow aspirate collected from the iliac crest had a higher mean concentration of osteoblastic progenitor cells compared with the distal aspect of the tibia or the calcaneus (p < 0.0001). There was no significant difference in concentration between the tibia and the calcaneus (p = 0.063). Age, sex, tobacco use, and diabetes were not predictive of osteoblastic progenitor cell yield.

CONCLUSIONS: Osteoblastic progenitor cells are available in the iliac crest, proximal aspect of the tibia, and calcaneus. However, the iliac crest provided the highest yield of osteoblastic progenitor cells.

CLINICAL RELEVANCE: The study demonstrated that osteogenic progenitor cells are available in bone marrow aspirate harvested from the tibia or calcaneus as well as the iliac crest. All three sites are easily accessed, with a low risk of adverse events. However, larger volumes of aspirate may be needed from the tibia or calcaneus to approach the yield of cells from the iliac crest.