AS: Ankle Spacer for Talar Osteochondral Defects

By means of the Ankle Spacer patients will be implanted, the clinical and radiological results of which will be prospectively recorded and analyzed at different points in time.

Ankle sprains can result in talar osteochondral defects (OCDs) which have a significant impact on the quality of life of patients. When these OCDs are of large nature (anterior-posterior or medial-lateral diameter \>1.5cm in diameter), cystic, have failed prior surgical treatment, or when there are multiple present on the talar articular surface, surgical care by means of fixation or bone marrow stimulation is contra-indicated. An ankle arthrodesis or fusion can be considered, but this results in functional limitation due to a decreased range of motion (ROM). In order to serve for a bone sparing prosthesis procedure, preserve range of motion, optimize physical functioning and to resurface the talus, the Ankle Spacer has been developed. It is a one-piece implant system that replaces the articulating upper talus surface of the tibio-talar joint, and offers several implant sizes in order to fit to the different talus sizes. It is anatomically designed to the native upper talus surface to provide an optimal fit to the distal articular surface. It has a rough titanium plasma spray (TPS) coated under surface with two posts and spikes for implant fixation. The rough surface enables secondary fixation by means of bone ingrowth and the spikes at the posterior part of the prosthesis allowing for optimal adherence of the implant and for minimal iatrogenic damage upon fixation. By these means, the anatomical situation and the natural congruency of the ankle joint are mirrored to a optimal extent. Despite the fact that no clinical trials have been published on this specific implant, it is hypothesized that the 5-year postoperative clinical outcomes concerning pain and prosthesis survival will be considered good.

Eligibility Criteria:
Inclusion Criteria:

* age ranging from 18 to 80 years
* talar osteochondral defect (multiple degenerative talar cysts present, and/or prior failed surgical treatment and/or multiple defects and/or large (\>15mm))
* willing to receive surgical implantation of the Ankle Spacer
* has been informed of the nature of the study and provided written consent
* The subject and treating physician agree that the subject will return for all required post-procedure follow-up visits
* failed previous conservative treatment
* complaints for at least 6 months

Exclusion Criteria:

* -severe ankle malalignement.(\> 5° varus/valgus).
* fracture \< 6 months - tendinitis - diabetes mellitus / rheumathoid arthritis
* advanced osteoporosis
* grade two or higher (Kellgren-Lawrence-Score) ankle joint degeneration on the tibia side.
* any ankle deformation that does not allow proper rasping of the cartilage and/or proper seating of the desired sized implant, as described in the surgical technique.
* blood supply limitations and previous infections, which may retard healing.
* foreign-body sensitivity. Where material sensitivity is suspected, appropriate tests should be made and sensitivity ruled out prior to implantation.
* active infection or blood supply limitations.
* conditions that tend to limit the patient's ability or willingness to restrict activities or follow directions during the healing period, including severe neuro-arthropathy.
* pathological conditions, such as insufficient quantity or quality of bone (e.g., cystic changes or severe osteopenia), which may compromise implant fixation.
* currently participating in an investigational drug or another device study that clinically interferes with the current study endpoints.
* Inability to be brought back to the surgery site for long term follow-up evaluations or the subject is unwilling to fill out the appropriate evaluation forms
* adiposity grade I (BMI \> 30 kg/m2)