Treatment strategies for proximal femur fractures in osteoporotic patients.

摘要

Fractures of the proximal end of the femur, together with vertebral fractures, are greatly exacerbated by osteoporosis and can be regarded as the most typical and most serious complications of this disease. The demand for prompt mobilisation with full loading of the affected limb, combined with a desire for the gentlest of treatments, becomes increasingly difficult to meet in ageing patients with advanced osteoporosis. The advantages of osteosynthesis in respect to these demands when operating on elderly patients with fractures do not apply due to the inability of the osteoporotic bone to hold the osteosynthetic components sufficiently until fracture healing occurs. This inability is related to the anatomy of the proximal end of the femur and its loading patterns. Under eccentric loading, high bending loads occur, leading to failure of the osteosynthetic anchorage at the center of the femoral head. This leads subsequently to stressful revision operations for the patient. The prosthetic replacement is agood option in cases of dislocated intracapsular fractures, but in cases of trochanteric fractures it is still debated. Therefore, it is vital for the trauma surgeon to have specific knowledge of the patient's bone quality in order to optimise the result of the preferred procedure. With reference to our own experimental research and a study of the current literature, this knowledge can be summarised as follows: the most stable anchorage for the implant is achieved by placing the implant through the midpoint of the femoral head (highest bone mineral density) or just below ("best backing"). Anchoring femoral head implants so that they are stable in rotation within the head-neck fragment will significantly raise their load bearing capacity. This is also true for intramedullary load bearing devices in trochanteric fractures. The distance between the load-bearing device in the femoral neck and the articular surface is inversely correlated to the stability at yield, as other studies have already shown. There seems to be a limit for a successful realisation of an osteosynthesis that lies at a femoral head bone mineral density of 250 mg/cm(3) calcium-hydroxyapatite (CaHAp). Nevertheless, high precision surgery in regard to fracture reduction and implant placement is a essential requirement for a successful osteosynthesis. Reproducible local measurements of bone mineral density and trabecular alterations, as well as quick screening methods, are very much desired by the authors.