Clinical outcome and explant histology after using a cellular bone allograft in two-stage total hip arthroplasty.

BACKGROUND: Although use of cellular bone allografts (CBA) in orthopedic surgery has become increasingly common, little information is available regarding their short-term clinical performance. In these two case reports of two-stage hip arthroplasties, ViviGen Formable CBA (V-CBA) was used in stage one to fill voids left by previous metal implants. METHODS: The two patients had distinctly different health profiles, but each of them had previous metal implants due to a hip fracture. In the otherwise healthy 49-year-old male patient, the total hip arthroplasty (THA) was performed 7 weeks after nail removal and V-CBA backfill. In the 64-year-old female patient with Type 1 diabetes and severe osteoporosis, stage 2 was performed after 12 weeks. At the time of THA for each patient, bone containing some V-CBA was removed to accommodate the hip implant. The explants were histologically analyzed for bone matrix, mineralization, and neovascularization. RESULTS: Histological staining showed substantial new bone formation and neovascularization in both explants albeit at different levels of maturity. CONCLUSIONS: Although limited, these results suggest that V-CBA may facilitate new bone formation in healthy as well as in metabolically challenged patients. LEVEL OF EVIDENCE: V, case report.