Treatment of Distal Femur Nonunion Following Initial Fixation with a Lateral Locking Plate.

Objective: To report and evaluate the outcomes of patients undergoing definitive treatment for distal femur nonunion after initial treatment with a locking plate.

Methods: Fourteen patients who had undergone definitive treatment at an academic Level 1 trauma center from May 2007 to December 2013 for distal femur nonunion were identified from a fracture database. Thirteen of them were female; the average age was 65 years (range, 50-84 years). Ten patients had sustained their injuries in falls at ground level, and four in motor vehicle accidents. Twelve patients were obese (body mass index ≥30), 10 had diabetes, none were current smokers, and one had an open fracture classified as type IIIa according to the Gustilo-Anderson classification system for open fractures. The fractures were classified according to the AO classification system for distal femur fractures; there were three type 33-A1, six 33-A2, two 33-A3 and three 33-C3 fractures. Methods of definitive treatment involved open reduction and internal fixation (ORIF) revision, medial plating, bone grafting and the use of other biologic materials.

Results: Eight of the 14 patients (57%) achieved union during follow-up. Definitive treatment for nonunion involved ORIF revision in 11 cases. Three patients who did not undergo ORIF revision were treated with iliac crest stem cell autografts, bone graft substitutes or recombinant human-bone morphogenetic protein-2 (rh-BMP-2). Other treatments included rh-BMP-2 (12 cases), iliac crest bone autograft (five), iliac crest stem cell autograft (two), crushed cancellous bone allograft (three), CaSO 4 and tricalcium phosphate bone graft substitute (two) and demineralized bone matrix (one). The average time from definitive treatment to union was 19 weeks (range, 12-51 weeks). Two of the 11 cases who underwent ORIF revision had medial plates added to improve biomechanical stability and prevent varus collapse. This was also performed in one patient with a grade III open type 33-C3 fracture and one with a closed 33-A2 fracture. Five study patients had comminuted fractures. Two had type 33-A3 and three type 33-C3 fractures. Both patients with 33-A3 fractures and 2 two with 33-C3 fractures had persistent nonunion at the end of follow-up.

Conclusions: Definitive treatment of distal femur nonunion after initial treatment with a locking plate had a low rate of success in this study, suggesting that this procedure is ineffective as a definitive treatment for distal femur nonunion.