Frontal plane fractures of the accessory carpal bone and implications for the carpal sheath of the digital flexor tendons

• DOI: 10.1111/evj.12203
• Publication Date: 2013-10-25T06:43:23Z
• Authors: G. J. Minshall; I. M. Wright
• Keywords: Male; 04 agricultural and veterinary sciences; Radiography; 0403 veterinary science; Fractures, Bone; Carpus, Animal; Tendon Injuries; Animals; Female; Horse Diseases; Horses; Retrospective Studies

SummaryReasons for performing studyAccurate radiological and ultrasonographic descriptions of frontal plane fractures of the accessory carpal bone (ACB) are lacking, and implications of these fractures for the carpal sheath and its contents have not previously been reported.ObjectivesAims were as follows: 1) to describe the location and radiological features of frontal plane fractures of theACB; 2) to document communication of displaced fractures with the carpal sheath and consequent injury to the deep digital flexor tendon (DDFT); 3) to describe ultrasonographic identification of lesions; and 4) to report tenoscopic evaluation and treatment.Study designRetrospective case series.MethodsAnalysis of frontal plane fractures of theACBreferred to a single hospital between 2006 and 2012, including review of radiographic, ultrasonographic and tenoscopic images.ResultsNine fractures were identified, of which 8 displaced fractures all communicated with the carpal sheath. Comminuted fragments and/or protruding fracture margins lacerated the lateral margin of the enclosedDDFT. This was identifiable ultrasonographically and confirmed at tenoscopy in 7 cases. Treatment in these horses consisted of removal of torn tendon tissue together with fragmentation and protuberant fracture edges, and 7 of 7 cases returned to work. One horse with a nondisplaced fracture was managed with immobilisation; the fracture healed, and the horse returned to work. One horse with a displaced fracture was retired to stud.ConclusionsFrontal plane fractures of theACBoccur palmar to the groove in its lateral margin for the tendon of insertion ofulnaris lateralis. Comminuted fragments can displace distally within the carpal sheath to a mid‐metacarpal level or abaxially to lie extrathecally, lateral to the parent bone. Displaced fractures communicate with the carpal sheath and traumatise theDDFT.