Review Question - QID 218525

This patient presents with recurrent ankle instability secondary to a cavovarus foot deformity with a plantarflexed first ray on initial radiographs. In the setting of a plantarflexed first ray, increased ankle inversion compared to the contralateral side, and rigid hindfoot varus deformity as demonstrated with lack of correction with Coleman block testing, a peroneus longus to peroneus brevis tendon transfer, lateral ankle ligament reconstruction, and lateralizing calcaneus osteotomy would be appropriate (Answer 4).

Cavovarus deformity of the hindfoot may be associated with ankle inversion instability, as this deformity predisposes patients to chronic insufficiency of the lateral ankle ligaments (anterior talofibular ligament, calcaneofibular ligament). Careful physical exam and radiographic evaluation are crucial to help guide surgical decision-making. Surgical management requires correction of the osseous deformities and soft-tissue imbalances, with a variety of surgical options available to address the multitude of possible concomitant pathoanatomic abnormalities. In the order presented above, each of the radiographic or physical exam findings is addressed separately with a corresponding surgical procedure (e.g., plantarflexed first ray addressed with peroneus longus to brevis tendon transfer).

Vienne et al. reviewed their postoperative outcomes of 8 patients (9 feet) presenting with cavovarus foot deformities and recurrent chronic lateral ankle instability. All were treated with lateralizing calcaneal osteotomy and peroneus longus to peroneus brevis transfer, with four patients undergoing additional Broström ligament reconstruction. The overall AOFAS-Score improved from 57 points preoperatively to 87 points postoperatively. They concluded that insufficiency of the lateral ligaments should be assessed and treated in a combined operative procedure to correct structured, static and dynamic components of the instability.

Strauss et al. reviewed the incidence of associated conditions in patients with chronic lateral ankle instability. Peroneal tendon injuries were the most common finding (28%), followed by os trigonum lesions (13%), lateral gutter ossicles (10%), and hindfoot varus alignment (8%). Twenty revision lateral ankle ligament reconstructions were required for either persistent pain or recurrent instability, and in this cohort the most common associated conditions were undiagnosed hindfoot varus alignment abnormalities (28%) followed by untreated peroneal injuries (25%). The authors concluded that awareness of these associated conditions is crucial, since they should be addressed concurrently at the time of surgery.

Figures A is the lateral radiograph of a cavovarus foot, with an increased lateral talo-first metatarsal angle (Meary's angle). Illustration A is a similar radiograph in a separate patient, with the typical findings of an increased apex-dorsal Meary's angle seen in cavovarus deformity.


Incorrect Answers
Answer 1: This combination of exam findings suggests a flexible hindfoot deformity, in which case lateralizing calcaneus osteotomy would likely be unnecessary. 
Answer 2: Patients with cavovarus foot deformities present with increased ankle inversion rather than eversion.
Answer 3: Patients with cavovarus foot deformities typically demonstrate increased ankle inversion rather than decreased eversion, as recurrent inversion sprains often leads to chronic attenuation of the lateral ankle ligament complex.
Answer 5: This patient would likely not need a lateral ankle ligament reconstruction, given their symmetric ankle inversion to the contralateral side. Furthermore, correction with Coleman block testing suggests that they have a flexible hindfoot deformity, foregoing the need for lateralizing calcaneus osteotomy.