Osteochondritis Dissecans of the Talus: A New Transmalleolar Fixation Technique

Abstract

Background:

Conservative management is the first line of treatment in most osteochondritis dissecans (OCD) cases and can be sufficient for small and stable lesions in skeletally immature patients. Unstable lesions commonly require surgical interventions and may need fixation. The standard surgical approach to fix posteromedial lesions of the talus involves an osteotomy of the medial malleolus. This technique is invasive and requires multiple weeks of immobilization after the surgery. In this video, we present a minimally invasive transmalleolar approach used for the fixation of an OCD lesion of the talus.

Indications:

The main indication for this procedure is the failure of conservative management with persistent ankle pain and functional impairment of an unstable osteochondral lesion with poor potential for revascularization.

Technique Description:

There are 3 key steps to this surgery: ankle arthroscopy, retroarticular drilling, and transmalleolar fixation. The transmalleolar approach is achieved by creating a tunnel through the medial malleoli oriented toward the lesion. To do so, the surgeon combines fluoroscopy and ankle arthroscopy to first insert a Kirschner wire (K-wire) through the medial malleoli. Once the correct orientation is confirmed, a 4.5-mm cannulated drill bit is used to create the tunnel. Arthroscopic visualization is used to avoid iatrogenic cartilage damage during drilling. Once the tunnel is created, ankle dorsiflexion and plantar flexion are used to access the entire lesion and insert screws. The malleolar tunnel is then filled with a bone graft and the wound closed. The patient is immobilized for 2 weeks after which gentle range of motion is initiated. The patient remains non-weight-bearing for 2 months and is then allowed to bear weight using a boot.

Results:

Transmalleolar fixation for osteochondritis dissecans of the talus is a minimally invasive procedure that does not require an osteotomy of the medial talus. This approach permits early postoperative range of motion and decreases postoperative pain and edema, but the adequate positioning of the tunnel can prove challenging.

Conclusion:

Transmalleolar approach to the talus is minimally invasive and allows adequate fixation of certain osteochondral lesions. Studies comparing the reoperation and complication rate with the standard malleolar osteotomy are lacking and need to be performed.

The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.

Graphical Abstract

This is a visual representation of the abstract.

Video Transcript

We present a case of unstable osteochondritis dissecans (OCD) of the talus treated using a new transmalleolar fixation technique. The authors have no conflict of interest to disclose.

The common surgical approach for grafting and fixation of posteromedial lesions of the talus involves an osteotomy of the medial malleoli. Other treatment options include arthroscopic techniques such as bone marrow stimulation. We present in this video a new minimally invasive transmalleolar approach to the talus. We describe this technique which first includes the arthroscopy of the ankle, followed by retroarticular drilling and finally transmalleolar fixation of the lesion.

The patient is a 16-year-old boy presenting with a 1-year history of incapacitating left ankle pain. His symptoms include pain, locking of the ankle with ambulation, and an abnormal gait. On examination, he had no effusion, a normal range of motion (ROM), and tenderness on palpation of the medial talar dome.

He has failed conservative management, which included non-weight-bearing with crutches for 6 months followed by physical therapy.

Magnetic resonance images show a 1 by 2 cm osteochondritis dissecans lesion on the talus. In addition to radiological signs of instability, a subchondral hollow and focal concavity are seen.

Clinical and radiological findings confirm the diagnosis of OCD of the talus. Combining the failure for conservative treatment, the unstable lesion needing fixation, and the medial lesion accessible by transmalleolar tunnel, the patient was consented for arthroscopic retrograde drilling and transmalleolar fixation using a transmalleolar tunnel.

Surgical indications for this treatment are unstable and symptomatic OCD lesions, failure of conservative management, and failure of previous retroarticular drilling. The OCD lesion must be salvageable (viable cartilage, reducible lesion). The size of the lesion that can be treated with this technique depends on the ability of the surgeon to reach it and insert the required number of screws or pins using the transmalleolar tunnel.

Contraindications are unsalvageable osteochondral fragments (extensive subchondral necrosis, cartilage fragmentation or degeneration), a patient unable to follow the postoperative instructions, and a central lesion inaccessible from the medial malleolar tunnel.

Other surgical techniques include OCD drilling to promote revascularization in stable lesions and debridement with microfracturing for small unstable non-salvageable lesions. Other procedures such as osteochondral autograft transfer system (OATS) and autologous chondrocyte implantation (ACI) are also options to restore cartilage in unstable larger lesions. As stated by Chau et al, treatment of OCD depends mostly upon skeletal maturity, stability of the lesion, and success or failure of nonoperative strategy.

The patient is positioned in a supine position with the operated leg bent at 90% and supported at the thigh. After being intubated, the patient’s leg is prepped and draped. A sterile external traction device is applied at the ankle. Using standard technique, anteromedial and anterolateral arthroscopy portals are created. The intra-articular anatomy is visualized, and the OCD lesion is identified. Using a hook probe, the OCD lesion is palpated. Its instability and the need for fixation are confirmed. A key step of this procedure is preparing the base of the lesion by exposing healthy subchondral bone to promote healing through retrograde drilling of the lesion. The surgeon identifies the entry point of the first K-wire approximately 3 cm distal to the external malleoli. Using anteroposterior and lateral views, the first wire is advanced aiming for the center of the OCD lesion.

Two additional K-wires are advanced parallel to the trajectory of the first wire. All wires are now removed of the talus. The next step of the procedure consists in creating a tunnel through the medial malleoli through which screws are going to be inserted. Under fluoroscopy visualization, a K-wire is inserted through the medial malleoli aiming toward the OCD lesion. Once adequate positioning and orientation are achieved, a cannulated 4.5-mm drill bit is used to drill a tunnel through the medial malleoli. Arthroscopic visualization is used to see the drill bit enter the joint space and make sure no cartilage is injured. To fix the OCD fragment, 3 headless screws are going to be inserted through the lesion. First, the posterior screw is to be inserted. To position the ankle adequately, the surgeon is about to diminish traction, put it in maximal plantar flexion, and the screw is to be inserted into the posterior third of the lesion. To insert the second screw in the middle third of the talus, the plantar flexion is slightly released and the screw is inserted. For the insertion of the last screw, the ankle is positioned in full dorsal flexion and the screw is inserted in an orientation parallel to the other 2 screws. Using the arthroscope through the malleolar tunnel, we are able to visualize the adequate positioning of the 3 screws. Fluoroscopy films allow us to appreciate the adequate positioning of the 3 screws. Once the screws are adequately positioned, the medial malleolar tunnel is closed using bone graft. The surgical wound is now closed in the usual manner, and the patient is transported in a stable position to the postoperative care unit.

Benefits of this approach include a minimally invasive procedure that does not require an osteotomy, decreased risk of tendons or neurovascular injury, decreased postoperative pain, and edema. Disadvantages of this procedure include specialized arthroscopic skills that are required, a more complex screw positioning that depends on the alignment and orientation of the malleolar tunnel, and a potentially weakened tibial plafond.

Potential complications include synovial cutaneous fistula, risk of infection, a weakened medial malleolus that can predispose the patient to the risk of a secondary fracture, and neurovascular injury which comes with any arthroscopy of the ankle.

Postoperative management includes non-weight-bearing for 2 months, followed by 1 month of weight-bearing with a boot. Range of motion is started at 2 weeks and the patient is followed up at 2 weeks for suture removal and at 3 months. The return to sport is gradual once the patient is able to ambulate and has a normal gait. At the last follow-up of this patient (8 months postoperatively), he reported no pain, a normal ROM, and complete return to his usual activities. Plain radiographs showed consolidation of the lesion and occlusion of the malleolar tunnel.

There is a lack of high-quality evidence in the literature to conclude on a definitive superior treatment for OCD of the talus. There are not enough reports in the literature about outcomes of surgical treatment of OCD in the pediatric population. Pallamar et al described good to excellent outcomes in 50% to 88% of their patients (n = 7) after fixation of OCD fragments. Outcomes of drilling were better than those of fixation of the lesion. Nevertheless, it is estimated that around 25% of patients who underwent retroarticular drilling for OCD will require a revision surgery.

The transmalleolar approach to the talus offers a minimally invasive option with a likely easier recovery but is technically challenging. The position of the screws depends on the adequate orientation and position of the malleolar tunnel. The outcomes of this novel surgical approach have not yet been compared with standard malleolar osteotomy.