Stress fracture of the palmar, distal cortex of the third metacarpal bone: A diagnostic challenge with a good prognosis.
Authors: Shan Ran, Johnston Anna S, Rosanowski Sarah M, O'Shea John, Riggs Christopher M
Journal: Equine veterinary journal
Summary
# Editorial Summary: Stress Fracture of the Palmar Distal Third Metacarpal Bone Transverse stress fractures of the palmar cortex at the distal third metacarpal bone remain poorly characterised in the equine literature despite causing significant diagnostic difficulty in racehorses. Ran and colleagues conducted a retrospective analysis of 23 cases diagnosed at the Hong Kong Jockey Club between 2011 and 2019, documenting clinical presentation, radiological features, and return-to-work outcomes through training records and lameness assessment. The majority of cases occurred in horses recently commencing or resuming training (57%), with most presenting as lame (87%, including severe lameness in 39%), localised soft tissue swelling (65%), and pain on palpation or flexion testing (65% and 52% respectively); radiographically, diffuse increased radiopacity, periosteal disruption, and splint bone button displacement were consistent findings. Strikingly, 61% of cases were initially misdiagnosed, yet 78% of horses successfully returned to training and racing with a median recovery time of 83 days to resume training and 246 days to race—a considerably favourable prognosis that should inform clinical decision-making. For practitioners managing racehorses in the early stages of preparation, heightened awareness of this injury pattern, recognition of its subtle but characteristic radiological signs, and understanding of its good long-term outlook may reduce diagnostic delay and inform more optimistic prognostication with owners.
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Practical Takeaways
- •Young racehorses at the start of or returning from training breaks are at high risk for this injury—maintain awareness during early training phases
- •This injury commonly mimics other conditions and is frequently missed on initial diagnosis; maintain high clinical suspicion when lameness and distal metacarpal pain occur in training horses without clear radiological findings
- •Prognosis is favourable with appropriate management; most affected horses return to racing, offering owners and trainers realistic expectations for recovery and return to work
Key Findings
- •23 cases of TSF PCD McIII identified; 57% had recently started or returned to training, with 35% sustaining injury before timed gallops
- •87% of cases presented with lameness (39% severe); 65% showed localised soft tissue swelling and pain on distal McIII palpation
- •61% of cases were initially misdiagnosed due to subtle radiological findings and inconsistent clinical presentation
- •78% of horses (18/23) successfully returned to training and racing with median recovery times of 83 days to training and 246 days to racing