Results of calcaneocuboid distraction arthrodesis.

BACKGROUND: One powerful method of reconstructing an adult acquired flatfoot deformity is a calcaneocuboid distraction arthrodesis. We performed a retrospective review of a small series of patients who underwent a calcaneocuboid distraction arthrodesis with a femoral head allograft. MATERIALS AND METHODS: Sixteen feet (14 patients) were identified with an average follow up of 23 months (8-39 months) and an average age of 43 years (16-60 years). A calcaneocuboid distraction arthrodesis was performed with a femoral head allograft, secured with a 3 hole 1/3 tubular plate with 7 of the grafts being supplemented with platelet rich plasma (PRP). Patients were kept non-weight bearing for 6 weeks with an additional 6 weeks in a walking cast or boot. Plain radiographs and if necessary a CT or MRI were used to evaluate for union. RESULTS: Seven of the 16 feet developed a nonunion. Five of 9 patients without PRP developed a nonunion vs 2 of 7 patients where PRP was used. CONCLUSION: Due to the unacceptably high complication rate with this procedure, the authors have abandoned this procedure. If an allograft is to be used for a calcaneocuboid arthrodesis, the authors strongly recommend using rigid locking fixation with a longer period of protected immobilization.

Spatial distribution of osteocyte lacunae in equine radii and third metacarpals: considerations for cellular communication, microdamage detection and metabolism.

Osteocytes, which are embedded in bone matrix, are the most abundant cells in bone. Despite the ideal location of osteocytes to sense the local environment and influence bone remodeling, their functions, and the relative importance of these functions, remain controversial. In this study, we tested several hypotheses that address the possibilities that population densities of osteocyte lacunae (Ot.Lc.N/B.Ar) correlate with strain-, remodeling- or metabolism-related aspects of the local biomechanical environments of mid-third diaphyseal equine radii and third metacarpals from skeletally mature animals. Ot.Lc.N/B.Ar data, quantified in multiple cortical locations, were analyzed for possible correlations with (1) structural and material characteristics (e.g., cortical thickness, percent ash, secondary osteon population density, mean osteon cross-sectional area, and predominant collagen fiber orientation), (2) strain characteristics, including prevalent/predominant strain magnitude and mode (tension, compression, shear), (3) hypothesized strain-mode-related microdamage characteristics, which might be perceived by osteocyte 'operational' networks, and (4) variations in remodeling dynamics and/or metabolism (i.e. presumably higher in endocortical regions than in other transcortical locations). Results showed relatively uniform Ot.Lc.N/B.Ar between regions with highly non-uniform strain and strain-related environments and markedly heterogeneous structural and material organization. These results suggest that population densities of these cells are poorly correlated with mechanobiological characteristics, including local variations in metabolic rate and strain magnitude/mode. Although osteocytes hypothetically evolved both as strain sensors and fatigue damage sensors able to direct the removal of damage as needed, the mechanisms that govern the distribution of these cells remain unclear. The results of this study provide little or no evidence that the number of osteocyte lacunae has a functional role in mechanotransduction pathways that are typically considered in bone adaptation.