Objectives: To report the outcome of unilateral surgery, by a plantaromedial approach, in 15 Labrador Retrievers with osteochondrosis dissecans (OCD) of the medial trochlear ridge of the talus. To evaluate the influence on outcome of age at surgery, bilateral involvement, periarticular soft tissue increase (PSI), osteophyte size (OS), decrease of range of joint motion and follow-up. To assess the extent of tarsal hyperextension in the standing dog. Methods: A retrospective clinical and radiographic study was conducted and the post-treatment gait was analysed using a force plate. Ground reaction force (GRF) data were compared with data derived from 24 healthy Labrador Retrievers (control group). Results: Six dogs had an excellent or good clinical result. Significant differences were found between the patients and the control group for many GRF data. Propulsive and vertical forces significantly decreased in the operated limb and increased in the contralateral pelvic and ipsilateral or both thoracic limbs. The lameness was significantly correlated to the OS postoperatively, the range-of-motion, the PSI, the length of the follow-up period, and the vertical ground force. No hyperextension in stance was recorded. Clinical significance: Although most dogs improved, the prognosis remains guarded. This seems to be independent of age, bilateral involvement, or preoperative OS in these dogs. No relation between medial talar OCD and tarsal hyperextension in stance was found in these dogs.