CHAPTER 32 Management of Osteochondral Lesions of the Talus

SURGICAL APPROACHES TO OSTEOCHONDRAL LESIONS OF THE TALUS

With osteochondral lesions (OCD) of the talus, surgery is performed only in symptomatic cases because the lesions do not show any marked tendency for progression and typically do not lead to osteoarthritis. These lesions are a very slowly progressive condition, so there should never be any sense of urgency to treat the lesion in the absence of symptoms that warrant intervention. I generally initiate treatment with arthroscopic debridement and microfracture. The results with arthroscopic treatment of OCD lesions are good to excellent in approximately 85% of patients at initial presentation. The results with repeat arthroscopy also are fairly good, depending on the extent of the lesion. If the lesion is very large, if previous operations have failed, or if the lesion is cystic, then osteochondral autograft or allograft procedures are preferable.

Once a decision has been made to proceed with surgical treatment, several factors should be considered in selecting a particular surgical approach: the size and depth of the lesion, the exact location of the lesion (medial versus lateral, anterior versus posterior), a history of previous surgical treatment, the stage of the disease, and the viability of the articular cartilage. Whenever possible, I treat the lesion either using arthroscopy or through anterior or posterior arthrotomy. To this end, flexion-extension lateral radiographs are useful to show the location of the lesion and its accessibility by arthrotomy as opposed to osteotomy, which is associated with far greater potential morbidity.

I generally initiate treatment arthroscopically, with abrasion, drilling, and microfracture (Figure 32-1). For lesions that are large and those that have not responded to arthroscopic treatment, use of an osteochondral graft should be considered. Moderate-size defects can be filled with several small osteochondral autografts from the ipsilateral knee. Larger defects, particularly those involving the medial or lateral talar wall, may require an allograft. These marginal sidewall lesions are difficult to treat with an osteochondral autograft because the graft must be inserted perpendicular to the axis of the talar dome. With these marginal defects, a medial or lateral malleolar osteotomy must be performed.

Figure 32-1 A, This is a typical posteromedial osteochondral lesion of the talus, as noted on the computed tomography scan, that is easily accessible and treatable arthroscopically. B, Arthroscopic view reveals softening demonstrated with use of a probe. C, The lesion was first debrided with curettage. D, This was followed by use of a shaver to create well-delineated margins.

Most anterior lesions are accessible for debridement and grafting with arthrotomy. However, if the lesion remains covered by the articular margin of the tibia, then creation of a small window in the anterior tibia is needed for further exposure. If extended visualization is required, this approach may be extended with an osteotomy of the anterior tibia, followed by replacement of the bone fragment and screw fixation.

APPROACH TO LATERAL TALAR DOME LESIONS

Most lateral talar dome lesions have a more anterior location, and if a graft is to be used, an anterolateral incision plus arthrotomy is used. The incision begins over the anterolateral aspect of the ankle, 2 cm proximal to the ankle joint, and is extended distally by 4 cm over the ankle joint (Figure 32-2). The intermediate dorsal cutaneous branches of the superficial peroneal nerve should be identified and protected. The extensor retinaculum is incised, the extensor digitorum longus tendon is identified and retracted medially, and the joint capsule is incised in line with the incision. Slight plantarflexion of the ankle will further facilitate exposure for access to debridement or grafting (Figure 32-3).

Figure 32-2 A, This large anterolateral osteochondral lesion of the talus had been twice treated with arthroscopy. B, An arthrotomy with osteochondral grafting was used for repair of the defect.

Figure 32-3 A-C, Anterolateral arthrotomy was used to treat an anterior lesion for which the patient had previously undergone unsuccessful arthroscopic debridement.

(Courtesy Dr. Clifford Jeng, Institute for Foot and Ankle. Mercy Medical Center, Baltimore, Maryland.)

A fibular osteotomy is rarely necessary to treat a lateral talar dome lesion and is used only for very large lesions that are located centrally or posterolaterally and that cannot be accessed with arthrotomy (Figure 32-4). If a fibular osteotomy is required, then I use a 6-cm incision over the distal fibula, starting from 1 cm distal to the joint and extending proximally. The osteotomy cut is made with a microsagittal saw, oriented obliquely at an angle from lateral and proximal to distal and medial, so that the distal edge is at the level of the joint line. The advantage of the oblique osteotomy is the greater surface area for healing, as well as preservation of the interosseous ligaments. The lesion is unlikely to be visible or accessible once the osteotomy has been performed. In the rare instance in which the lateral lesion has a more central location and cannot be accessed by simply inverting the ankle, an anterolateral tibial osteotomy, in addition to the fibular osteotomy, can provide excellent visualization of the lesion.

Figure 32-4 A, This large cystic lesion previously had been treated arthroscopically, which failed to relieve the patient’s symptoms. B, An osteotomy of the fibula was used to begin definitive surgical treatment. The osteotomy shown is not in an optimal location—it is too transverse and includes disruption of the syndesmosis. C and D, The fibula was retracted laterally and the lesion exposed. E, An osteotomy of the distal lateral tibia was performed to obtain complete exposure of the lesion. F, The defect was debrided and the matched graft inserted. G, The osteotomy both the tibia and the fibula was then repaired, with the syndesmosis included in the fixation. H and I, Appearance of the healed lesion at 3 years after surgery.

For any graft procedure to be performed, the lesion must be fully visible, and any graft must be inserted perpendicular to the talar surface. For this reason, an osteotomy of the lateral wall of the distal tibia often is required. The osteotomy cut must be large enough that after the graft is inserted, the piece of tibia that has been removed can be replaced and fixed with screw(s). At the completion of the intraarticular procedure, the fibular osteotomy is anatomically reduced and held with a lateral plate. The interosseous ligaments should be repaired if disrupted; likewise, if the syndesmosis was disrupted, one or more syndesmotic screws, as required, should be inserted through the plate.

For large cystic anterolateral lesions, an osteotomy of the fibula is not enough, and an osteotomy of the anterior tibia will be needed for exposure of the defect, as shown in Figure 32-5. In the case illustrated, a massive defect of the anterior talus was in a more central location and therefore inaccessible for grafting with the arthrotomy alone. The treatment plan was to use an osteoarticular allograft to fill the defect, but because the graft had to be inserted perpendicular to the axis of the talus, a tibial osteotomy was necessary. The osteotomy was made in an oblique plane (as a large fracture of the anterolateral distal tibia); 90% of the cut was made with a saw, with completion achieved by fracturing the tibia using an osteotome. The osteotomized bone was then peeled laterally, retaining the soft tissue attachments including the anterior inferior syndesmotic ligament (see Figure 32-5).