Lateral ankle instability

[The periosteal flap augmentation technique in chronic lateral ankle instability]

OBJECTIVE

Anatomic repair of the lateral ligament complex of the ankle joint and augmentation with an autologous pedicled periosteal flap of the distal fibula following identification and concomitant treatment of intra-articular pathologies.

INDICATIONS

Symptomatic chronic mechanical lateral ankle instability. As a modular step in the treatment of osteochondral lesions in conjunction with lateral ankle instability.

CONTRAINDICATIONS

Higher degree osteoarthritis of the ankle joint (>Kellgren/Lawrence 2 and 4 or Outerbridge 3 and 4) and/or hindfoot deformity; mechanical incompetence of both the fibulotalar anterior ligament and the fibulocalcaneal ligament preventing anatomical reinsertion; general risk factors.

SURGICAL TECHNIQUE

Diagnostic arthroscopy for identification and treatment of intraarticular pathologies; verification and grading of ligamentous instability (medial, lateral, combined). Open exposure of the distal fibula and the ruptured components of the lateral ankle ligament complex. Anatomic reinsertion of the original ligaments and assessment of their mechanical competence. Apart from the situation in the juvenile patient with a thick periosteal layer a doubled and pedicled periosteal strip of the distal fibular periosteum will suffice for the augmentation in one ligamentous component, only. Fixation in the talus or calcaneus is achieved via suture anchors, screws with a washer or transosseous fixation via interference screw.

POSTOPERATIVE MANAGEMENT

Postoperative immobilization in a lower leg split cast or a splint until wound healing (5-8 days), mobilization in a walker or an ankle orthosis with consecutive full weight-bearing for further 4-5 weeks. Proprioceptive and pronator muscle training, optionally insole or lateral wedge at the shoe sole for 6 months postoperatively. Avoidance of contact sports for 4-6 months.

RESULTS

Several studies have reported reliable restoration of ligamentous ankle stability with overall success rates >90% and good to excellent total results in >90% of patients with limited minor complications. In view of the heterogeneous data from previous studies, some recent studies have demonstrated that the outcome after periosteal augmentation is comparable to that after techniques employing free tendon graft for anatomic restoration of ligamentous ankle stability. The technique has been applied successfully in cases of poor mechanical properties of the formerly ruptured ligaments and in patients with a high functional demand.