Healing the humeral shaft nonunion: Prior surgery confers increased risk of recalcitrant nonunion.

Objectives: To determine the rate of successful humeral shaft nonunion repair in patients with no prior surgery on the humerus (failed nonoperative management), compared to patients with a history of prior surgery on the humerus (initial operative treatment complicated by nonunion, or prior attempted nonunion repair after failed nonoperative management).

Methods design: Retrospective.

Setting: Two academic trauma centers (one level 1 and one level 2).

Patient selection criteria: All skeletally mature patients undergoing nonunion repair of a presumed aseptic humeral shaft nonunion (AO/OTA 11A, 11B, 11C, 12A, 12B, 12C) were eligible for inclusion.

Outcome measures and comparisons: The primary outcome was osseous union. Univariate analysis was used to examine patient, injury, and treatment factors associated with recalcitrant nonunion between those with and without prior surgery.

Results: One hundred fifty-nine patients were included. Eighty-two patients had a history of prior operative treatment. The group with prior operative treatment was significantly younger (47 vs 52, p=0.047) and had fewer comorbidities (average Charlson comorbidity score 1.3 vs 1.9, p=0.015). There were 34 men in the group with prior operative treatment, compared to 37 in the group without (p=0.493). For patients with prior operative treatment, 17/82 (21%) developed a recalcitrant nonunion, versus 2/79 (3%) in patients with no prior operative treatment (p<0.001). The number of prior operations on the arm was significantly associated with increased risk of recalcitrant nonunion (3% risk if no prior surgeries, 19% risk with one prior surgery, 25% risk with 2 prior surgeries, 33% risk with 3 prior surgeries, p=0.004). No demographic factors were associated with development of a recalcitrant nonunion (p>0.05 for all). Nine patients had unexpected positive cultures but this was not associated with increased risk of recalcitrant nonunion (22% in patients with infection vs 26% in those without, p=0.907).

Conclusions: Patients undergoing nonunion repair after prior operative treatment of a humeral shaft fracture had a 1 in 5 rate of recalcitrant nonunion, while patients undergoing initial nonunion repair after failed nonoperative management had a 3 in 100 rate of recalcitrant nonunion. Increased risk of persistent nonunion stemmed not from initial treatment strategy for the acute fracture, but rather from the presence of any prior surgery.

Level of evidence: III.