Summary Reasons for performing study: Subchondral cystic lesions of the medial femoral condyle (SCMFC) are well documented in horses 3 years; arthroscopic debridement or enucleation of the cyst is currently the surgical treatment of choice. However, studies of occurence and outcome following surgery in older horses are lacking. Objective: To identify factors important in outcome for horses with SCMFC treated by arthroscopic debridement. Hypothesis: Age of horse at presentation has a significant influence on return to work following arthroscopic treatment for SCMFC. Clinical and diagnostic findings are also significant with respect to prognosis. Methods: A retrospective review of medical records from 6 equine referral centres identified 85 horses that underwent arthroscopic debridement of SCMFC. Clinical examination, radiographic and arthroscopic findings were analysed together with follow‐up data. Univariable analysis and multivariable logistic regression models were used to determine factors affecting return to soundness. Event‐time analysis was performed to evaluate return to work. Results: Older horses (>3 years) were less likely to return to soundness (P = 0.02) or to work (P = 0.04) than younger horses (> 3 years). Of 39 horses age 0‐3 years, 25 (64%, 95% CI 49‐79%) returned to soundness. Of 46 horses age >3 years, 16 (35%, 95% CI 21‐49%) returned to soundness. In addition, cartilage damage at sites other than the SCMFC negatively affected prognosis (P = 0.05). The hospital where treatment was performed had no influence on return to soundness. Conclusions: Older horses carry a worse prognosis for both return to soundness and return to work. Potential relevance: It is important for clients to be made aware of the difference in outcome between age groups.

Summary Reasons for performing study: Radiography is a very important aspect of equine stifle imaging. The precise radiographic anatomy of the soft tissue structures of the equine stifle has not been described previously. Objective: To describe the anatomical relationship between sites of attachment of soft tissue structures of the equine stifle and their locations on standard radiographic views. Methods: The sites of bony attachments of the tendons, ligaments and fibrous portion of the joint capsules of equine stifles were determined by gross dissection. These sites of attachment were transposed onto one set of bones deprived of soft tissue and mapped using radiopaque markers. This specimen was then radiographed in the standard radiographic projections (lateromedial, caudocranial and caudal 60° lateral‐craniomedial oblique) to determine the position of the attachment sites on the radiographs. Results: Two radiographic maps were drawn per radiographic projection, one for the attachment sites of the ligaments and tendons and one for the attachment sites of the joint capsules. Conclusions and potential relevance: The radiographic maps of the precise position of the soft tissue attachments of the tendons, ligaments and joint capsules of the equine stifle should assist interpretation of equine stifle radiographs.

Horses with infection of the CDET and its sheath may be returned to long-term soundness without gait abnormality after radical resection.

Gentamicin-impregnated polymethylmethacrylate beads were used to treat infective arthritis in the small tarsal joints of 11 severely lame horses. Under general anaesthesia, between five and 10 beads were placed into a 7 to 8 mm tract drilled across the affected joint and, in all except one horse, they were left in place for 14 days. Two of the horses were euthanased for reasons other than persistent tarsal joint sepsis, but the other nine survived and seven of them returned to their previous level of athletic performance.