Tarsocrural arthroscopy for osteochondrosis dissecans: clinical features of a referral hospital population and prevalence of abnormalities within the plantar pouch

Reasons for performing study:

There is limited information on tarsocrural arthroscopy for osteochondrosis dissecans lesions (OCD) in Great Britain, and routine examination of the plantar pouch has not been described.

Objectives:

To describe clinical features of cases undergoing tarsocrural arthroscopy for OCD and estimate the prevalence of abnormalities within the plantar pouch.

Study design:

Retrospective case review.

Methods:

Case records of all horses that had tarsocrural arthroscopy for OCD at Rossdales Equine Hospital between 1 January 2005 and 31 December 2013 were included (n = 99). Descriptive data and 95% confidence intervals (CI) were constructed in Microsoft Excel.

Results:

Warmbloods/Warmblood-crosses were significantly over-represented compared to the normal hospital population, comprising 42.4% (CI 32.7–52.2%) of the study (P<0.001), followed by Thoroughbreds/Thoroughbred-crosses (33.7%, CI 25.0–43.7%), 22 other horse breeds and one pony. Cases were predominantly male (70.7%, CI 63.6–81.3%) with 48.5% geldings, 19.2% colts and 3.0% stallions. Median age was 2.9 years (0.1–13.5 years) and median weight was 523 kg (112–919 kg). Most were nonracing sports horses (40.4%, CI 30.7–50.1%), or unbroken (27.0%, CI 18.5–36.0%) with the remainder used for breeding, general purpose or racing. Reasons for presentation were lameness (52.7%, CI 42.5–63.0%), effusion (36.3%, CI 26.4–46.1%), or survey radiographs (11.0%, CI 4.6–17.4%). Tarsocrural arthroscopy was most frequently performed bilaterally (41.8%, CI 32.1–51.6%), followed by left hind (35.7%, CI 26.2–45.2%), then right hind (22.4%, CI 14.2–30.7%). Irrespective of pathology in the dorsal pouch, examination of the plantar pouch was performed in 70 joints (50 horses), and in 78.0% (CI 66.5–89.5%) abnormalities were found. Of these, 10 required removal of organised fibrinous debris or osteochondral fragments (25.6% CI 11.9– 39.3%), none of which were recorded using diagnostic imaging presurgery.

Conclusions:

Investigation of the plantar pouch is indicated in routine tarsocrural arthroscopy for OCD as it often reveals additional pathology, which may necessitate surgical intervention. Further work will evaluate how plantar pouch pathology may influence prognosis.