Revision osteosynthesis after primary treatment of atypical ulnar fractures associated with bisphosphonate usage - Nonunion after ordinary open reduction and internal fixation.

backgroundWe performed revision surgeries to treat nonunion of bisphosphonate-associated ulnar fractures that had originally been treated, after misdiagnosis, using the typical open reduction/internal fixation (ORIF).

methodsOf nine cases of ulnar nonunion initially treated at other institutions, we performed revision surgeries on four that met our inclusion/exclusion criteria. All previous implants were removed; the areas of nonunion were resected, and strut bone grafts were inserted and fixed with locking plates. Radiological assessments were performed monthly for 3 months after surgery and then every 3 months for 1 year.

resultsAll patients were female, with a mean age of 71.8 years. All patients had been taking bisphosphonate for a mean of 7.2 years. The primary fixation methods used at other institutions were intra-medullary nailing (n = 1) and placement of 3.5-mm locking plates (n = 3). In one patient (patient 1), the contralateral (right) ulna developed a new fracture at 1 month after revision surgery on the left ulna. Another patient (patient 3) exhibited an incomplete fracture in the contralateral (right) ulna. All four patients exhibited hip fractures (bilateral in three). All revisions resulted in final union at a mean of 4.8 months postoperatively.

conclusionAtypical ulnar fractures should be suspected in elderly women on long-term bisphosphonate treatment. Union will fail with standard ORIF for atypical ulnar fractures, because the fracture occurred due to compromised normal bone metabolism as reflected in the bone resorption, remodeling, and healing processes. Revision osteosynthesis using a locking plate with callus resection and strut/cancellous bone graft provided satisfactory results. LEVEL OF EVIDENCE: Therapeutic level IV.