Open debridement of osteochondral lesions can be performed through a variety of approaches.18 Most lateral lesions are anterior and can be treated through a standard anterolateral arthrotomy. A skin incision is made just medial to the fibula about 2 cm proximal to the joint and extended 1 to 2 cm distal to the joint. Branches of the superficial peroneal nerve are carefully protected, and the extensor retinaculum is incised. The extensor digitorum longus tendons are retracted medially, and the joint capsule is incised in line with the skin incision. Visualization of the articular surface may be improved with plantarflexion of the ankle. In the rare occurrence of a postero-lateral lesion, a fibular osteotomy and incision through the anterior syndesmosis can be performed.
Figure 67-9 Transmalleolar drilling with a small-joint drill guide inserted through the anteromedial portal. Visualization is through the anterolateral portal. OLT, osteochondral lesion of the talus. (From Ferkel TD, Scranton PR: Current concepts review: Arthroscopy of the foot and ankle. J Bone Joint Surg Am 1993;75:1233-1242.)
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Medial lesions may be difficult to visualize both arthroscop-ically or with a standard medial arthrotomy. In these cases, a medial malleolar osteotomy can be performed. Numerous techniques have been described in an attempt to minimize the complications associated with this procedure. Although this approach provides excellent visualization, there is a risk of malunion, nonunion, hardware complications, and articular cartilage injury.
Since there are no universally accepted guidelines in the literature, internal fixation of loose or displaced fragments remains somewhat controversial. In general, patients suitable for internal fixation are younger patients with acute traumatic lesions. The ideal type of fragment should be 1 cm or greater and have a large piece of attached subchondral bone, and the overlying articular cartilage should be in good condition.8 The ideal type of fixation is also controversial. Metal implants provide good fixation with excellent biocompatibility but may require a second procedure for removal. This is a particularly difficult problem for posteromedial lesions that required a medial malleolar osteotomy. Bioab-sorbable fixation devices are another alternative. These devices have the advantage of not requiring later removal, but bone resorption around the implants remains a concern.
Autologous osteochondral grafts from the ipsilateral knee are transplanted to the talus using the mosaicplasty technique.19 The procedure can be used as an initial procedure for larger lesions or for revisions that have failed previous arthroscopic procedures. Lesions should be over 1 cm in size, and the cartilage on the remainder of the tibia and talus should be normal. Specialized instruments are used to remove osteochondral plugs from the non-weight-bearing portion of the medial femoral condyle. The talar lesion is then prepared and the plugs are inserted perpendicular to the articular surface. Anterolateral arthrotomies are usually sufficient for lateral lesions, and medial lesions usually require a medial malleolar osteotomy. The procedure replaces the defect with hyaline cartilage and can replace lost subchondral bone stock. Disadvantages include potential donor site morbidity in the knee, and complications associated with open arthrotomies and osteotomies.
One of the newer techniques used to treat osteochondral lesions of the talus is autologous chondrocyte transplantation.20,21 The exact indications for this procedure are still evolving but are similar to mosaicplasty. The procedure is performed in two stages. The first stage requires an arthroscopic cartilage biopsy either from the knee or from the non-weight-bearing portion of the anterior talus. The chondrocytes are then grown in culture for approximately 2 to 3 weeks. This is followed by the second procedure that uses an arthrotomy or osteotomy. The lesion is debrided back to normal cartilage with a bleeding subchondral bed. A 10 X 10-mm cortical window is then made in the distal tibia metaphysis, and cancellous bone graft is removed. This graft is packed into the base of the defect to restore subchon-dral bone stock. A periosteal flap is then harvested from the ipsi-lateral proximal tibia and is sewn over the defect with a 5-0 polydiaxone monofilament suture. The cultured chondrocytes are then injected under the periosteal flap, and then the flap is sealed with fibrin glue. The theoretical advantage of this procedure is that it replaces lost subchondral bone stock and hyaline cartilage is restored to the articular surface. The two main disadvantages are the high cost of the procedure and the need for two operations. Further research comparing autologous chon-drocyte transplantation to other procedures are needed to determine whether the high cost of this procedure is justified in treating osteochondral lesions of the talus.
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