OBJECTIVE Subchondral decompression and revascularization in Osteochondrosis dissecans (OCD) of the talus with cartilage preservation. METHODS Symptomatic talar OCD stage I and II, i.e., cartilage intact or almost intact. METHODS Talar OCD stage III and IV, i.e., cartilage not intact. METHODS Diagnostic ankle arthroscopy. Insertion of dynamic reference base (DRB) in the talar neck through a stab incision. After 3D image acquisition and planning of the drilling, navigated drilling with a 5 mm drill. Insertion of a 1 mm titanium wire into the canal and 3D image acquisition for evaluation of the canal. Autologous cancellous bone transplantation into the canal. Arthroscopic evaluation. METHODS For 6 weeks, 15 kg partial weight bearing without immobilization. After 6 weeks full weight bearing. RESULTS A total of 52 patients with symptomatic talar OCD stage I and II were included in a clinical follow-up study. Time needed for preparation, including the placement of the DRB, scanning time, and preparation of the trajectories was 7 min 32 s (4-30 min). In 50 cases (96%), the drilling was judged with 3D imaging to be correct. In the remaining 2 cases (4%), the drilling ended in the caudal portion of the lesion. A perforation of the cartilage was not registered arthroscopically. Follow-up after 12 months (range 6-36 months) was possible in 48 patients (92%). Three patients (6%) had been converted to bone cartilage transplantation (OATS) due to recurrent symptoms. These patients were excluded from follow-up. The follow-up scores were Visual Analogue Scale Foot and Ankle (mean 93 points [range 86-100 points]) and the SF 36 (standardized to 100 point maximum, 90 points [range 79-100 points]).