Osteochondromata of the caudal distal radius are an important cause of tenosynovitis of the carpal sheath of the digital flexor tendons in young racing Thoroughbreds. When present in the most common location of the middle one-third of the bone, they are likely to cause impingement damage to the deep digital flexor tendon. Tenoscopic surgery offers a good prognosis.

COMP concentrations in DFTS synovial fluid were significantly greater than those in normal horses with noninfected tenosynovitis caused by intrathecal tendon/ligament tearing, but not by other lesions.

In contrast to previously described amputation techniques, subtotal (cranial wedge) ostectomy removes only impinging portions of SPs. General anaesthesia and lateral recumbency facilitate access and enable a short surgery time. The procedure maintains the contour of the back and has fewer complications, but produces functional outcomes similar to more invasive procedures.

Tearing of the calcaneal insertions of the SDFT should be included in the differential diagnoses of lame horses with distended calcaneal bursae. Tearing of the tendon fibrocartilage cap in horses with unstable displacement of the SDFT is a plausible explanation of the clinical features of the injury and explains previously unreliable results of reconstructive surgeries. Subtotal resection is a technically demanding technique but appears to offer an improved prognosis.

Summary Reasons for performing study: Clinical association between the branches of insertion of the suspensory ligament (SL) and metacarpophalangeal (MCP) and metatarsophalangeal (MTP) joints has been reported. However, there has been no assessment of the lengths of the SL branches which are subsynovial with respect to the joints or reports of involvement of the MCP/MTP joints in injuries of the SL branches. Objectives: To establish proportions of SL branches subsynovial with respect to the MCP/MTP joints and report clinical and arthroscopic findings in horses with desmitis of SL branches identified as having an articular component to the lesion. Hypothesis: Arthroscopic surgery enables identification and potential treatment of intra‐articular injuries of SL branches. Methods: Twelve forelimbs and 13 hindlimbs were dissected and the total and subsynovial lengths of the SL branches recorded. Case records of horses with intra‐articular injuries of the SL branches were reviewed and 18 animals identified. Diagnostic information and arthroscopic findings were recorded and results of treatment determined by telephone follow‐up. Results: Of SL branches, 28.45% in the forelimb and 29.56% in the hindlimb were subsynovial to the MCP and MTP joints. All animals with intra‐articular lesions of the SL branch were lame and had distension of the affected MCP/MTP joint. In 16 horses (17/22 branches), there was palpable thickening of the affected SL branch. Disrupted infrastructure was evident ultrasonographically in 15/17 branches and involvement of the dorsal articular surface of the ligament was predicted in 12/17 branches. Following arthroscopic intervention, 13 horses returned to work at a level equal to or greater than that achieved prior to injury and 2 returned to work at a lower level. Three horses incurred separate injuries and were retired or subjected to euthanasia. Conclusions: Articular involvement should be considered in animals with injuries of an SL branch and concurrent distension of the MCP/MTP joint. Arthroscopy is necessary to identify such lesions confidently and to direct case management. Potential relevance: Arthroscopy of the MCP/MTP joints can make a positive contribution to the assessment and management of some SL branch injuries.