- Osteochondral talar lesions and Ankle biomechanics

An osteochondral defect (OCD) of the talus involves the articular cartilage and subchondral bone. Patients are often young, active people with deep ankle pain during weightbearing. Trauma, like an ankle sprain, is the most frequent etiologic factor. Most talar OCDs are treated by means of arthroscopy, during which a bone marrow stimulation technique aims at filling of the defect and covering the subchondral bone.

This thesis aims at defining the most effective surgical treatment for talar OCDs, and how to improve treatment by investigating ankle biomechanics, evaluating existing techniques and developing new techniques. To accomplish this aim, treatment results, complications in ankle arthroscopy, normal motion patterns of the ankle and arthroscopic access to the talar dome were studied. Furthermore, a new secondary treatment method for talar OCDs was developed. The aims were investigated in a total of 11 chapters.

The most important findings were: Arthroscopic treatment by means of bone marrow stimulation is the treatment of choice for primary osteochondral lesions. Use of the dorsiflexion method in ankle arthroscopy is related to a significantly lower number of complications than average mentioned in literature. The mean orientation of the finite helical axes during ankle motion leads to coupling of inversion to internal rotation and eversion to external rotation. Absence of this coupling may indicate pathology. On average, a part of the posterocentral talar dome is hard to reach by arthroscopy. A new focal metal implant is a promising secondary treatment option for talar OCDs.