Outcomes of nonunion repair for distal femur fracture nonunion.

Objectives: To report the outcomes aseptic distal femur nonunion repair and to identify factors associated with recalcitrant nonunion.

Methods: Design: Retrospective cohort study.

Setting: Single academic level 1 trauma center.

Patient selection criteria: All skeletally mature patients undergoing repair of a presumed aseptic distal femur nonunion (AO/OTA 33A or 33C) between 2005-2023 were eligible for inclusion.

Outcome measures and comparisons: The primary outcome was the success of an initial nonunion repair attempt. Univariate and multivariable analysis was used to examine patient, injury, and treatment factors associated with recalcitrant nonunion.

Results: One hundred and two patients were included. Their average age was 56 (SD 15) and 64 were female. Forty-seven patients had open fractures and 60 patients had high energy mechanisms. Fifty three fractures were AO/OTA type 33A, while 49 were type 33C. The rate of recalcitrant nonunion was 23%. Diagnosis of fracture related infection (FRI) after the index nonunion repair was associated with increased risk of recalcitrant nonunion (47% with FRI vs 18% without FRI, p=0.021). Nonunion repair with a nail plate combination was significantly associated with decreased risk of recalcitrant nonunion (0/27, 0%) compared to repair with plate alone (8/28, 29%), nail alone (4/10, 40%), or graft alone (9/25, 36%), p<0.001. Looking at dual-column fixation constructs as a whole (including nail + plate, plate + endosteal plate or medial strut, dual-plate), fixation with a dual column construct was again associated with a lower rate of recalcitrant nonunion (1/36, 3%) compared to nail alone (4/10, 40%), plate alone (8/28, 29%), or graft alone (9/25, 36%), p<0.001.

Conclusions: Nearly one in four patients developed a recalcitrant nonunion after attempted nonunion repair. Fixation with a dual-column construct was associated with decreased risk of recalcitrant nonunion.

Level of evidence: III.