Radius and ulna fracture repair with the IMEX miniature circular external skeletal fixation system in 37 small and toy breed dogs: A retrospective study

Bierens D, Unis MD, Cabrera SY, Kass PH, Owen TJ, Mueller MG. Vet Surg. 2017 May; 46 (4): 587-595.

OBJECTIVE: To determine outcome and prognostic factors after radius and ulna fracture repair with a modified IMEX miniature circular external skeletal fixation (MCESF) in small and toy breed dogs.

STUDY DESIGN: Retrospective study.

SAMPLE POPULATION: Thirty-seven young small and toy breed dogs with 41 radial and ulnar fractures.

METHODS: Records of radial and ulnar fractures repaired with a modified IMEX MCESF were reviewed. Constructs included 3-4 complete rings, 2 threaded rods, 4 mm-diameter nuts and 6-8 transfixation wires. MCESF configuration, type of fracture reduction, dynamization of the apparatus, inclusion of a dowel pin, and implantation of allograft were recorded. Outcome measures included complications, limb alignment, time to clinical union, and functional outcomes, scored as excellent, good, fair, or poor.

RESULTS: Radiographic union was achieved in 40/41 fractures. Fractures reached bony union within 33-84 days after repair. Time to union was not influenced by the type of fracture reduction (P = .11), use of a dowel pin (P = .099), or implantation of an allograft (P = .45). Fracture dynamization delayed radiographic union (P = .0005). At implant removal, mean frontal (FPA) and mean sagittal plane alignments (SPA) were 7.9° ± 6.5° and 7.5° ± 5.8°, respectively. Limb alignment did not differ between radiographs obtained immediately after surgery and those obtained at time of radiographic union in the frontal (P = .062) or sagittal (P = .14) planes. Ninety-five percent of cases had good-to-excellent outcomes, based on return to function at final re-evaluations.

CONCLUSION: This modified IMEX MCESF construct provided an effective alternative to treat young small and toy breed dogs with radius and ulna fractures.