Abstract
Introduction: Lateral insufficiency fractures following total hip replacements have been reported with the femoral stems positioned in varus, together with osteopenia of the lateral femoral cortex. Any abnormal alignment of the lower limbs, such as genu valgum, will alter the load distribution across the femoral cortices, and repetitive loading during walking will predispose the bones to stress fractures at any stress riser point, such as the tip of a femoral component. Bilateral femoral stress fractures post total hip replacements have not been previously described
Materials and Methods: We present a 55 yr old lady, diagnosed with juvenile idiopathic arthritis aged 5 years, and had undergone bilateral total hip replacements at the age of 29 and 30 years and bilateral knee replacements aged 37 and 42 years. The right hip required revision of the cup 15 years later. The knees were in valgus and the left knee was extremely stiff flexing to just 5 degrees. She presented to us as an emergency with bilateral thigh pain with plain radiographs confirming bilateral peri-prosthetic fractures of the femur at the tip of well fixed femoral components. There had been no history of injury and her hips were functioning well up to this time.
Results: The patient required revision of both hips to long stem un-cemented components, bypassing the fractures, and revision of both knees to stemed seni-constrained implants, thereby correcting the alignment of both lower limbs.
Both fractures healed and the patient is currently pain free and mobile with walking aids.
Discussion: Surgeons must remain aware that when implants are in situ, abnormal alignments will lead to abnormal forces, and stress fractures are likely to occur at any stress riser around the implant. Avoiding mal-alignment will avoid this complication.
Bilateral peri-prosthetic stress fractures following total hip replacements have not been previously reported.
Correspondence should be addressed to Mr John Hodgkinson, BHS, c/o BOA, The Royal College of Surgeons, 35–43 Lincoln’s Inn Fields, London WC2A 3PE.
