FEMORAL SPLIT FRACTURE AFTER UNCEMENTED TOTAL HIP REPLACEMENT.

Abstract

Introduction: Since 2000 all total hip replacements have been subjected to a continuous quality control. We report an increasing rate of postoperative fractures around uncemented femoral components after minimal or no trauma.

Methods: Four to 6 weeks after the THR all patient files and radiographs are evaluated and demographic data, complications and radiographic position of the implant registered. Surgery was performed according to the manufacturer’s instructions, and full weight bearing was allowed. If a fracture occurred during the first postoperative weeks a further analysis of the case was performed.

Results: During the 9 years 3.295 primary total hip replacements were performed. In the period the use of uncemented THR increased from 41% to 99%. Totally 69 fractures in 2.408 uncemented THR’s (2.9%) were registered, and 28 of these were of the proksimal split fracture type occurring without any previous trauma. The fractures occurred after a few days up to 4 weeks after surgery and were characterised by a vertical femoral fracture from the calcar to the medial femoral region 5 to 7 cm below the lesser trochanter. All cases were seen in women, but were not correlated to age, BMI or previous femoral neck fracture. In most cases treatment was internal fixation with a trochanteric grip and cables and insertion of a new uncemented femoral component.

Conclusion: The increased use of uncemented femoral components implies a substantial risk of subtrochanteric femoral fracture. The cause of these fractures is unknown, but probably multifactorial. It could be due to a mismatch between the instruments and the prosthesis, to undiagnosed weakness of the bone, or to the vigorous mobilisation made possible by the effective modern treatment of postoperative pain.