Slab fractures of the third carpal bone involving both radial and intermediate facets and outcomes after surgical repair in racing Quarter Horses.

BACKGROUND Characteristics and outcomes after surgical repair of third carpal bone (C3) slab fractures involving both radial and intermediate facets in racing Quarter Horses are unknown. OBJECTIVES To describe the pre- and intraoperative characteristics of C3 slab fractures of both radial and intermediate facets in Quarter Horses and to report on the long-term outcomes after internal fixation. STUDY DESIGN Retrospective case series. METHODS Case records were collected from racehorses with C3 slab fractures between 2008 and 2020. Inclusion criteria required arthroscopic-guided repair of C3 slab fractures involving both radial and intermediate facets in Quarter Horses. Routine C3 slab fractures (single facet), fractures in other breeds or those repaired with other techniques were excluded. Outcomes were obtained by standardised questionnaire. Data were presented as mean ± SD or as proportions with 95% confidence interval (CI). RESULTS Of 22 Quarter Horses with C3 slab fractures involving both radial and intermediate facets, 91% (CI 79%-100%; n = 20) were collapsing and 91% (CI 79%-100%; n = 20) had avulsion of the medial palmar intercarpal ligament. Articular cartilage erosion and osteochondral fracture of the radial carpal bone was observed in 91% (CI 79%-100%; n = 20) and 41% (CI 20%-62%; n = 9) cases respectively. At 5.5 ± 3.9 years after surgery, 86% (CI 72%-100%; n = 19) were alive and used for breeding or retirement. Of 18 horses with follow-up >1 year, 39% (CI 16%-61%; n = 7) resumed some athletic activity. MAIN LIMITATIONS Cases were referred specifically for surgical repair and horses with fractures considered too severe for surgical intervention or euthanasia at owner request were not included. Questionnaire responses are susceptible to recall bias. CONCLUSIONS Horses with C3 slab fractures of both radial and intermediate facets that are repaired have a favourable prognosis for retirement, breeding and potentially low-level athletic activity.