Four horses presenting for lameness were diagnosed with unilateral osteochondral fragmentation (OCF) of the palmarolateral/plantarolateral aspect of the distal phalanx within the distal interphalangeal joint (DIPJ). Histological evaluation of one case supported a diagnosis of osteochondritis dissecans (OCD), with patient age and history from two cases suggesting a traumatic origin. Lesion appearance on conventional radiography, computed tomography (CT), nuclear scintigraphy and magnetic resonance imaging (MRI) are described. Fragmentation was best identified on dorsal 65° proximal-palmaro/plantarodistal oblique (D65°PrPDiO/D65°PrPlDiO) and dorsal 65° proximal-palmaro/plantarodistal lateral oblique (D65°Pr45°L-PDiMO/D65°Pr45°L-PlDiMO) radiographic projections of the foot, but articular pathology appeared more severe on cross-sectional imaging modalities. In all cases, lameness was refractory to conservative management. Arthroscopic evaluation of the DIPJ was performed in three horses, although the lesion was inaccessible in two. In one horse, access to the lesion was possible due to increased joint laxity, presumably due to concurrent soft tissue injury. One horse was euthanased after failed conservative management, one was pasture sound following palmar digital neurectomy 12 months after initial presentation, one returned to racing and one was lost to follow-up. Osteochondral fragmentation at this location has not previously been described, treatment options are limited and the prognosis appears to be poor.

中文翻译：

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四匹马远端指骨掌外侧/跖外侧的骨软骨碎裂：一个新的位置

出现跛行的四匹马被诊断为远端指间关节 (DIPJ) 内远端指骨掌外侧/跖外侧的单侧骨软骨碎裂 (OCF)。一个病例的组织学评估支持剥脱性骨软骨炎 (OCD) 的诊断，两个病例的患者年龄和病史表明创伤起源。描述了常规射线照相、计算机断层扫描 (CT)、核闪烁扫描和磁共振成像 (MRI) 上的病变外观。在背侧 65° 掌近端/跖远端斜肌 (D65°PrPDiO/D65°PrPlDiO) 和背侧 65° 掌近端/跖远端侧斜肌 (D65°Pr45°L-PDiMO/D65°Pr45°L-PlDiMO) 上最好识别碎片) 足部的射线照相投影，但在横断面成像模式下，关节病变似乎更为严重。在所有情况下，跛行都是保守治疗难以治愈的。DIPJ 的关节镜评估在三匹马中进行，尽管有两匹马无法触及病变。在一匹马中，由于关节松弛度增加，可能接近病变部位，这可能是由于同时发生的软组织损伤。一匹马在保守治疗失败后被安乐死，一匹马在初次就诊后 12 个月在手掌指状神经切除术后恢复正常，一匹马重返赛场，一匹失访。该位置的骨软骨碎裂以前没有被描述过，治疗选择有限，预后似乎很差。DIPJ 的关节镜评估在三匹马中进行，尽管有两匹马无法触及病变。在一匹马中，由于关节松弛度增加，可能接近病变部位，这可能是由于同时发生的软组织损伤。一匹马在保守治疗失败后被安乐死，一匹马在初次就诊后 12 个月在手掌指状神经切除术后恢复正常，一匹马重返赛场，一匹失访。该位置的骨软骨碎裂以前没有被描述过，治疗选择有限，预后似乎很差。DIPJ 的关节镜评估在三匹马中进行，尽管有两匹马无法触及病变。在一匹马中，由于关节松弛度增加，可能接近病变部位，这可能是由于同时发生的软组织损伤。一匹马在保守治疗失败后被安乐死，一匹马在初次就诊后 12 个月在手掌指状神经切除术后恢复正常，一匹马重返赛场，一匹失访。该位置的骨软骨碎裂以前没有被描述过，治疗选择有限，预后似乎很差。一匹马在保守治疗失败后被安乐死，一匹马在初次就诊后 12 个月在手掌指状神经切除术后恢复正常，一匹马重返赛场，一匹失访。该位置的骨软骨碎裂以前没有被描述过，治疗选择有限，预后似乎很差。一匹马在保守治疗失败后被安乐死，一匹马在初次就诊后 12 个月在手掌指状神经切除术后恢复正常，一匹马重返赛场，一匹失访。该位置的骨软骨碎裂以前没有被描述过，治疗选择有限，预后似乎很差。