Low field magnetic resonance imaging of palmar osteochondral fragmentation of the distal phalanx

Summary Background The presence of palmar osteochondral fragments of the distal phalanx is a newly recognised cause of foot lameness with only a few cases having been reported. Objectives To describe the low field magnetic resonance imaging (MRI) appearance of palmar articular fragmentation of the distal phalanx and concurrent abnormalities of the distal interphalangeal joint (DIPJ); to investigate the prevalence of these fragments in a population of sports and pleasure horses and their potential clinical significance. Study design Retrospective descriptive case series. Methods This is a retrospective descriptive case series in which all Sports and Pleasure horses undergoing standing low‐field MRI of the feet between 2015 and 2023 were reviewed. Appearance, location and number of palmar articular fragments were recorded. When a palmar fragment was present, abnormal findings of the DIPJ were graded. Results A total of 855 horses underwent MRI examination of one or both front feet. Palmar osteochondral fragmentation of the distal phalanx was identified in four horses (0.4% prevalence), three Lusitanos and one Warmblood. The age range was 4–17 years old. All fragments were located along the palmarolateral margin of the glenoid of the distal phalanx in front feet. Concurrent imaging abnormalities of the joint were present in all four horses. Main limitations Lack of histopathology. Conclusions The prevalence of palmar articular fragments of the distal phalanx was low in this population of horses. Palmar osteochondral fragmentation must be considered when evaluating lameness localised to the foot, since it was identified only in lame limbs and associated with other imaging abnormalities of the DIPJ.