Surgical results of atypical femoral fractures in long-term bisphosphonate and glucocorticoid users - Relationship between fracture reduction and bone union

Atypical femoral fracture (AFF) associated with bisphosphonate (BP) use is common, and its pathophysiology is considered to involve severely suppressed bone turnover. Surgical results following AFF fixation have not been optimal, with some cases resulting in delayed union or nonunion. Regarding bone healing, glucocorticoid (GC) has similar properties to BP. We investigated the surgical results of AFF fixation in both users of BP and GC, especially with regard to intraoperative fracture reduction. We included 12 AFFs in 11 patients with a follow-up over one year who all took GC for autoimmune disease and BP for management of GC-induced osteoporosis. Their mean age was 62 years and 10 patients were female. Six fractures were located in the subtrochanteric region of the femur and six were in the diaphysis. Intramedullary nails were used to treat all fractures. Union rate was recorded, and the status of the reduction immediately after the operation was analyzed. Four of the 12 cases developed nonunion, and three of them required additional surgery. The relationship between alignment, cortical continuity, fracture gap, and bone union was not significant. In the nonunion cases, cortical continuity on the anteroposterior and lateral views were never confirmed. Even if cortical continuity in either of the views was there, the two limbs resulted in nonunion. One third of the patients with AFF secondary to long-term BP and GC use developed nonunion despite their fracture reductions being acceptable. We consider strict reduction should be needed for these cases with disadvantage condition to bone union.