PERIPROSTHETIC FRACTURES OF THE FEMUR AFTER HIP ARTHROPLASTY: REVISION OF THE STEM

Periprosthetic femoral fractures after hip replacement (HA) represent a difficult treatment challenge and often is associated with an high incidence of complications and failures. The true incidence of these fractures is uncertain ranging from 0.1 to 2.1%. With the increasing prevalence of HA and revision HA, along with an aging population, the number of these fractures can be expected to increase. Risk factors can be general, such as osteoporosis, or more localized such as osteolysis or iatrogenic cortical defects. Not rarely stem loosening is associated. This combination can lead to a fracture with minimal trauma. The aims of treatment should be a united fracture in anatomic alignment with a stable prosthesis. Treatment principles depend on the localization of the fracture in relation to the femoral component, stability of the stem, quality and quantity of the bone host, age and medical comorbidities as well as surgeon’s preference and experience. Vancouver classification is the most used classification system for these fractures and aids in the decision making process. Fractures around the stem with loose implants and adequate bone stock (B2) need to be revised. In loose implants with inadequate bone stock (B3) specialized implants and technique are necessary as well as some form of bone grafting. Dislocation of the existing stem, cement removal, reaming of the femoral canal and final insertion of the implant are all potentially hazardous. It is important to obtain adequate surgical exposure, which may involve a trochanteric osteotomy and sometimes transfemoral Wagner approach. Many surgeons suggest the use of long-stem cemented revisions. More recently, the use of uncemented prosthesis has been favoured because cement may interpose between the fracture fragments and inhibit union. Uncemented, proximally porous-coated implants have been used but this type of implant may not be stable in the femur in cases of poor proximal bone stock. Alternatively, revision with a long cementless stem, fixed distally with porous-coating, provides both implant stabilisation and fracture fixation. Distal fixation has also been achieved with good results using grooved or slotted long-stems like the Wagner system. Distally locked stems have recently used, but there is little objective data on the outcome of these devices. In these cases that need stem revision adequate reaming is essential and it is preferable to over-ream rather than to risk fracture during the insertion of press fit stems. It may be useful to strengthen the femur prophylactically with a bone clamp or using circlage wires.