A 7‐year‐old Holsteiner gelding was presented with a left common digital extensor sheath effusion of one‐year's duration. Radiographic examination revealed two extra‐articular mineralised bodies adjacent to the dorsolateral carpometacarpal joint. Ultrasonography confirmed an intrathecal location of one mineralised body in the common digital extensor sheath, palmar fraying of the common digital extensor tendon and tenosynovitis. Ultrasound could not confirm whether the second mineralised body was intrathecal or located external to the common digital extensor sheath. Common digital extensor tenoscopy facilitated removal of both mineralised bodies and revealed a fistula communicating with the carpometacarpal joint. The mineralised bodies, initially thought to be synovial osteochondromas, were histologically identified as para‐articular osteochondromas. There are no previously published reports of para‐articular chondroma/osteochondroma in the horse. Despite surgical removal of the para‐articular osteochondromas, concern for future extensor sheath distension remained given the communication between the carpometacarpal joint and common digital extensor sheath.

中文翻译：

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普通指伸肌腱鞘与掌指关节之间的关节旁骨软骨瘤伴滑膜间瘘

出现了7岁的Holsteiner胶凝，伴有持续时间为一年的左侧常见数字伸肌鞘积液。影像学检查发现在背外侧腕掌关节附近有两个关节外矿化体。超声检查证实在一个普通指伸肌鞘中一个矿化体的鞘内位置，一个普通指伸肌腱的手掌磨损和腱鞘炎。超声无法确定第二个矿化体是鞘内还是位于普通指伸肌鞘外部。常见的数字伸肌腱镜检查有助于去除两个矿化体，并揭示了与腕掌关节相通的瘘管。矿化体最初被认为是滑膜骨软骨瘤，在组织学上被鉴定为关节旁骨软骨瘤。以前没有关于马关节旁软骨瘤/骨软骨瘤的报道。尽管通过外科手术切除了关节旁骨软骨瘤，但由于腕掌关节和普通指伸肌鞘之间的连通，仍对未来的伸肌鞘扩张仍然存在担忧。