Union Rates and Reported Range of Motion Are Acceptable After Open Forearm Fractures in Military Combatants
Authors: Nappo Kyle E. , Hoyt Benjamin W. , Balazs George C. , Nanos George P. , Ipsen Derek F. , Tintle Scott M. , Polfer Elizabeth M. 
Published: March 2019

Abstract

Background
High-energy open forearm fractures are unique injuries frequently complicated by neurovascular and soft tissue injuries. Few studies have evaluated the factors associated with nonunion and loss of motion after these injuries, particularly in the setting of blast injuries.

Questions/purposes
(1) In military service members with high-energy open forearm fractures, what proportion achieved primary or secondary union? (2) What is the pronation-supination arc of motion as stratified by the presence or absence of heterotopic ossification (HO) and synostosis? (3) What are the risks of heterotopic ossification and synostosis? (4) What factors may be associated with forearm fracture nonunion?

Methods
A retrospective study of all open forearm fractures treated at a tertiary military referral center from January 2004 to December 2014 was performed. In all, 76 patients were identified and three were excluded, leaving 73 patients for inclusion. All 73 patients had serial radiographs to assess for HO and union. Only 64 patients had rotational range of motion (ROM) data. All patients returned to the operating room at least once after initial irrigation and débridement to ensure the soft tissue envelope was stable before definitive fixation. The indication for repeat irrigation and débridement was determined by clinical appearance. Patient demographics, fracture and soft tissue injury patterns, surgical treatments, neurovascular status at the time of injury, incidence of infection, heterotopic ossification (defined as the presence of heterotopic bone visible on serial radiographs), radioulnar synostosis, bony status after initial definitive treatment (union, nonunion, or amputation), and forearm rotation at final followup were retrospectively obtained from chart review by someone other than the operating surgeon. Seventy-six open forearm fractures in 76 patients were reviewed; 73 patients were examined for osseous union as three went on to early amputation, and 64 patients had forearm ROM data available for analysis. Union was determined by earliest radiology or orthopaedic staff official dictation stating the fracture was healed. Nonunion was defined as the clinical determination by the orthopaedist for a repeat procedure to achieve bony union. Secondary union was defined as union after reoperation to achieve bony union, and final union was defined as overall percentage of patients who were healed at final followup. Of the patients analyzed for union, 20 had less than 1 year of followup, and of these, none had nonunion. Of the patients analyzed for ROM, eight patients had less than 6 months of followup (range, 84-176 days). Of these, one patient had decreased ROM, none had a synostosis, and the remaining had > 140° of motion.

Results
Initial treatment resulted in primary union in 62 of 73 patients (85%); secondary union was achieved in eight of 11 patients (73%); and final union was achieved in 70 of 73 patients (96%). Although pronation-supination arc in patients without HO was 140° ± 35°, a limited pronation-supination arc was primarily associated with synostosis (arc: 40° ± 40°; mean difference from patients without HO: 103° [95% confidence interval {CI}, 77°-129°], p < 0.001); patients with HO but without synostosis had fewer limitations to ROM than those with synostosis (arc: 110° ± 80°, mean difference: 77° [35°-119°], p < 0.001). Heterotopic ossification developed in 40 of 73 patients (55%), including a radioulnar synostosis in 14 patients (19%). Bone loss at the fracture site (relative risk (RR) 6.2; 95% CI, 1.8-21) and healing complicated by infection (RR, 9.9; 95% CI, 4.9-20) were associated with the development of nonunion after initial treatment. Other potential factors such as smoking status, vascular injury, both-bone involvement, need for free flap coverage and blast mechanism were not associated.

Conclusions
Despite a high-energy mechanism of injury and high rate of soft tissue defects, the ultimate probability of fracture union in our series was high with a low infection risk. Nonunions were associated with bone loss and deep infection. Functional motion was achieved in most patients despite increased burden of HO and synostosis compared with civilian populations. However, if synostosis did not develop, HO itself did not appear to interfere with functional ROM. Future investigations may provide improved decision-making tools for timing of fixation and prophylactic means against HO synostosis.

Level of Evidence
Level III, therapeutic study.