The femoral head expandable peg: improved periimplant bone properties following expansion in a cadaveric model

Abstract

The femoral head expandable peg offers a new concept of bone-device purchase treating proximal femur fractures. We describe the expansion influence on both the periimplant bone properties and the intraosseous pressure. A 10 x 8 mm cannulated peg consisting of a stainless steel oval-shaped transversely sectioned rod was tested on 13 femoral heads retrieved from patients with subcapital fracture treated by hemiarthroplasty. Normal saline solution was used to expand the diameter of its membrane from 7.8 to 10.5 mm, resulting in abutment of the distal peg to the compacted cancellous bone of the femoral head. The intraosseous pressure was monitored using a 1.4 mm drill-hole. Dual-energy X-ray absorptiometry and microradiography demonstrated increased periimplant bone density following peg expansion, without significant increase in the intraosseous pressure. The new implant afforded improved periimplant bone density, less trabecular damage and preservation of bone stock, all contributing to reliable biomechanical support and potentially decreasing the high complication rate following screw fixation in osteoporotic femora. Further studies are needed in order to establish clinical safety and efficacy.