Osteochondral lesion of the talus (OLT) may cause significant pain and mechanical symptoms in the involved ankle.
The talar articular surface is enclosed within the osseous structures of the ankle mortise.
Sammarco and Makwana3 described treatment of OLT through a “trap door” osteotomy with an autogenous talar autograft obtained from a non–weight-bearing portion of the talus.
Surgical reconstruction of OLT may require osteotomy of the tibia or fibula for adequate exposure. Traditionally, osteotomy of the malleoli (medial and lateral) have been described in order to obtain access for cartilage grafting of these lesions. Malleolar osteotomies are unstable and typically require an extended period of non–weight bearing for adequate osseous healing. Nonunion of malleolar osteotomies may occur and may require further surgery.
The anterior trap door osteotomy was developed as a stable alternative to malleolar osteotomies. This osteotomy is intrinsically stable and can be fixed with absorbable pins, facilitating postoperative imaging.
INDICATIONS
The anterior trap door osteotomy is indicated for exposure during surgical treatment of OLT. Typically, this type of exposure is necessary for cartilage grafting procedures such as osteochondral allograft or autograft reconstruction of a defect.
The osteotomy can be used for lesion of the anterior two-thirds of the talar dome. The osteotomy can be placed medially, centrally, or laterally, depending on the location of the talus which requires exposure.
SURGICAL MANAGEMENT
Patient Positioning
The patient is positioned supine under appropriate anesthesia, with thigh tourniquet control. The patient is placed on a beanbag patient positioner to facilitate positioning of the extremity. The patient is rolled laterally toward the operative extremity for medial lesions and can be rolled medially for central and lateral lesions. The leg, ankle, and foot are prepared and draped from below the knee distally.
Approach
For a medial lesion, a 7-cm anteromedial longitudinal incision is made over the ankle joint parallel to the medial talar facet. Dissection is carried medial to the tibialis anterior tendon, taking care to identify and protect the saphenous vein and nerve.3
Central lesions use a midline incision centered over the ankle mortise. The superficial peroneal nerve is identified in the subcutaneous tissue over the anterior ankle and the extensor retinaculum is divided. The interval between the tibialis anterior and extensor hallucis longus (EHL) tendons is used, identifying the deep peroneal nerve and anterior tibial artery which must be protected and retracted laterally with the EHL tendon.2
An anterolateral osteotomy can be used for OLT in the lateral talar dome.1 An incision is made centered over the tibiofibular joint and dissection carried out through the extensor retinaculum. The superficial peroneal nerve will be directly in the field and must be identified and protected. Dissection over the anterior tibia is done, and the anteroinferior tibiofibular ligament must be incised in its midportion to remove the tibial trapdoor fragment. This should be sutured for repair during closure.
The soft tissue is dissected to the ankle joint and a capsulotomy performed.
Enough capsule is stripped from the tibia to expose the medial half of the joint.
A synovectomy is performed if needed.
TECHNIQUES
Tibial Osteotomy Using the Trap Door
Opening the Tibial Trap Door
Strip the periosteum proximally along the distal tibial metaphysis to the upper limit of the wound.
Make a 1-cm mark on the medial tibial plafond beginning at the angle of Hardy (TECH FIG 1A).
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