Short Incomplete Sagittal Fractures of the Proximal Phalanx in Ten Horses Not Used for Racing

Abstract

To describe short incomplete sagittal fractures of the proximal phalanx (type Ia P1 fractures) in horses not used for racing and report outcome. Retrospective study. Horses (n=10) with type Ia P1 fractures. Retrieved data of horses with type Ia P1 fractures were signalment, history and results of orthopedic examination. Radiographs were re-evaluated for position and length of the fracture line, presence of osteoarthritis or subchondral cystic lesions (SCL), periosteal new bone formation and subchondral sclerosis. Conservative treatment (n=4) included box confinement for 2 months followed by 1 month of hand walking. Surgical therapy (n=6) consisted of internal fixation by screws inserted in lag fashion in 5 horses. Concurrent SCL were debrided by curettage via a transcortical drilling approach. In 1 horse, only SCL curettage but not internal fixation was performed. Outcome was assessed on a clinical and radiographic follow-up examination in all horses. Mean follow-up time was 27 months (median, 13.5 months; range, 9 months to 9 years). All horses treated with internal fixation were sound at follow-up and had radiographic fracture healing. Of the 4 horses managed conservatively, 3 remained lame and only 1 horse had radiographic evidence of fracture healing. Catastrophic fracture propagation occurred in 2 horses not treated by internal fixation, 20 and 30 months after diagnosis, respectively. Horses with a type Ia P1 fracture treated surgically had a better outcome than those managed conservatively and lack of fracture healing seemingly increases the risk of later catastrophic fracture. Surgical repair of type Ia P1 fractures should be considered to optimize healing and return to athletic use.