Novel analysis model for implant osseointegration using ectopic bone formation via the recombinant human bone morphogenetic protein-2/macroporous biphasic calcium phosphate block system in rats: a proof-of-concept study

PURPOSE: The osseointegration around titanium mini-implants installed in macroporous biphasic calcium phosphate (MBCP) blocks was evaluated after incubation with recombinant human bone morphogenetic protein-2 (rhBMP-2) in an ectopic subcutaneous rat model. METHODS: Mini-implants (phi1.8x12 mm) were installed in MBCP blocks (bMBCPs, 4x5x15 mm) loaded with rhBMP-2 at 0.1 mg/mL, and then implanted for 8 weeks into subcutaneous pockets of male Sprague-Dawley rats (n=10). A histomorphometric analysis was performed, and the bone-to-implant contact (BIC) and bone density were evaluated. RESULTS: Significant osteoinductive activity was induced in the rhBMP-2/bMBCP group. The percentage of BIC was 41.23+/-4.13% (mean+/-standard deviation), while bone density was 33.47+/-5.73%. In contrast, no bone formation was observed in the bMBCP only group. CONCLUSIONS: This model represents a more standardized tool for analyzing osseointegration and bone healing along the implant surface and in bMBCPs that excludes various healing factors derived from selected animals and defect models.

Irreducible traumatic posterior hip dislocation with entrapment and a buttonhole effect / 中华创伤杂志(英文版)

The authors reported the case of a 27-year-old man who sustained an irreducible postero-lateral traumatic dislocation of the hip with capsular and labral entrapment. Initial X-rays showed only a small acetabular fragment. After two attempts to reduce the hip with muscle paralysis under general anaesthesia failed, the patient was treated by immediate open reduction through a postero-lateral approach. Surgical exploration of the hip revealed a small osteochondral fragment attached to a large piece of labrum and capsule, clogging the acetabulum. The femoral head crossed over the torn capsule with a buttonhole effect. These elements were relieved, the bone fragment was fixed with a 2 mm screw and the capsule was repaired. At the 10-year follow-up, the functional outcome was excellent with a Harris score of 100 points and no signs of necrosis or osteoarthritis. The authors propose a literature review of this uncommon lesion.