An OATs-type procedure is reserved for patients who have been treated with arthroscopic cleaning out (debridement) and microfracture and are still not doing well or patients that have a very large (>20mm²) talar OCL. This procedure may also be called a mosaicplasty. An OATs-type procedure involves taking a bone and cartilage plug for another site such as the knee and transplanting it into the talar lesion which is first cored out (See Figure 3). It is also possible to use a plug of bone and cartilage taken from a cadaver although there is some question about the viability of the cartilage cells in these grafts. The theoretical advantage of this procedure is that it replaced the damaged cartilage with real cartilage taken from somewhere else. However, the main disadvantage is that in order to gain access the injured part of the talus it is usually necessary to cut one of the bones of the ankle, essentially creating a controlled ankle fracture. This explains why the recovery time for this procedure is about three times longer for that of an arthroscopic debridement and microfracture and the complication rate is higher. Essentially it is a much more involved operation.
If there is other significant pathology this may also need to be addressed at the time of surgery. This may include:
- Surgery to address ankle instability such as a Brostom lateral ligament repair or a lateral ligament tendon reconstruction.
- Calcaneal osteotomy to address significant hindfoot alignment abnormalities (usually hindfoot varus treated with a lateralizing calcaneal osteotomy)
For and OATs-type procedure can be prolonged. Patients often require 6-8 weeks of non-weight bearing following surgery to allow the osteotomy (bone that was cut) site to heal. Physical therapy and gradually increasing activity is then undertaken. Full recovery can take 12-15 months although 80% of the recovery may be achieved within the first 6 months. Athletes can expect to return to their sport in 9-9 months. There is an estimated 75-85% success rate for this type of procedures.
This surgery may lead to a number of standard surgical complications such as:
- Wound healing problems
- Deep Vein Thrombosis (DVT)
- Pulmonary Embolism (PE)
- Nerve injuries
- Complex Regional Pain syndrome (CRPS)
- Persistence of symptoms
Along with above basic complications, there are specific complications associated with arthroscopic debribement and microfracture of talar osteochondral lesions including:
- Failure of graft
- Arthritis in the ankle joint
- Transmission of disease or infection if an allograft is used
- Non-union of the osteotomy site
- Pain or symptoms at the harvest site