A computer assisted surgical technique for retrograde autologous osteochondral grafting in talar osteochondritis dissecans (OCD): a cadaveric study

This study describes a new method for the treatment of osteochondritis dissecans (OCD) in the medial talar dome. Ten cadaveric lower extremities were used to develop and evaluate a retrograde osteochondral grafting technique applying computer-assisted surgery. With the help of a computed tomography (CT)-based navigation system, a guide wire was placed from the lateral talar process into the posteromedial talar trochlea where OCD lesions are predominantly located. Cannulated reamers and arthroscopic shavers were used for the preparation of the recipient hole. The grafts, with diameters of 4.5 mm, 6.5 mm or 8.5 mm were harvested from the lateral femoral trochlea and inserted in a retrograde fashion. The last five cadavers were analyzed for accuracy of surface reconstruction and graft stability. For this purpose a medial malleolar osteotomy and a CT scan was performed. We found steps in the joint surface to range from 0.5 mm to 1.5 mm (mean 0.9 mm, SD 0.4) with the graft always below the surrounding cartilage. Graft subsidence occurred at an applied force of 26.4 +/- 4.6 N. This study indicates that osteochondral cylinders can be inserted in a retrograde fashion to reconstruct the posteromedial talus. Good surface congruency and sufficient graft stability can be achieved.