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Osteotomies for the Correction of Varus Ankle


Indications

  • Malaligned ankles with medial osteoarthritis

  • Malunions after distal tibial fractures or malleolar fractures

  • Realignment prior to total ankle replacement (TAR) or ankle fusion

  • Corrections after malpositioned TAR or ankle fusion

  • Medial osteochondritis dissecans of the talus

Indications Pitfalls

  • Loss of >50% of tibiotalar joint surface (plain radiographs, magnetic resonance imaging, arthroscopy) may be treated with TAR or ankle fusion.

  • Lack of compliance with the postoperative non–weight-bearing program caused by neurologic disease or poor health status may be treated by ankle fusion.

Indications Controversies

  • Altered bone quality (medication, large cysts, osteopenia/osteoporosis).

  • Tobacco use should be considered a relative contraindication.

  • Inflammatory, systemic joint diseases incorporating the ankle joint are usually treated with TAR or ankle fusion.

Examination/Imaging

  • Assess the patient’s gait and the alignment of the lower extremity.

  • While the patient is sitting with free-hanging feet, perform the anterior drawer test and talar tilt test to assess ankle joint stability. Furthermore, assess the inversion/eversion force (function of posterior tibial and peroneal muscles) and subtalar range of motion.

  • Perform the Coleman block test to exclude a forefoot-driven hindfoot deformity.

  • Weight-bearing radiographs of the foot (dorsoplantar, lateral), the ankle (anteroposterior), and a Saltzman view are recommended to assess the nature and location of the deformity. If a deformity at the level of the knee joint or the femur cannot be excluded clinically, whole lower limb radiographs are obtained ( Fig. 52.1 ).

    FIG. 52.1

  • Next to radiographs, computed tomography (CT) and magnetic resonance imaging (MRI) are not routinely required. However, they could be of value when assessing rotational malalignment, osteochondral lesions, and tendon disorders or when evaluating the ligaments. Weight-bearing CT scans can additionally be performed in case of asymmetric ankle osteoarthritis (tilt of the talus in the ankle joint mortise).

  • Combined single-photon emission and computed tomography (SPECT) scan is a valuable tool for staging of ankle osteoarthritis.

  • Assess the medial distal tibial angle on a weight-bearing anteroposterior radiograph of the ankle joint (angle between the tibial axis and the tibial joint surface). The wedge to be corrected can be measured out of the radiograph or calculated with the mathematical formula tan α = H/W, where α is the angle to be corrected, H is the wedge height in millimeters, and W is the tibial width.

  • Distinction between congruent and incongruent ankle joints is helpful in determining the type of osteotomy performed (tibia only vs. tibia and fibula; wedge osteotomy vs. dome-shaped osteotomy).

  • A dome-shaped osteotomy should be considered for deformities that cannot be corrected at the center of rotation of angulation (CORA) as well as for large corrections (to avoid excessive translation of the distal fragment).

  • Congruent joints should be considered for dome-shaped osteotomies; incongruent joints usually qualify for wedge osteotomies.

  • Additional correction of the length and rotation of the fibula must be considered in order to preserve the ankle joint congruency.

Treatment Options

  • Conservative treatment (i.e., shoe modifications, braces, physical therapy for peroneal tendon strengthening)

  • Ankle fusion or TAR in advanced stages of ankle osteoarthritis

  • Calcaneal displacement osteotomy is an alternative surgical treatment. Commonly, correction of malalignment is best performed at the level of the deformity

Surgical Anatomy

  • Medial approach: the great saphenous vein and the saphenous nerve usually lie anterior to the incision. The posterior tibial tendon runs immediately posterior to the medial malleolus under the tendon sheet.

  • Lateral approach: the sural nerve and the short saphenous vein run dorsal to the line of the incision and are usually not seen during this procedure. Extended proximal dissection may require exposure of the branches of the superficial peroneal nerve. Cauterization of some of the branches of the peroneal artery, which lie deep to the medial surface of the distal fibula, may be necessary.

  • Anterior approach: the neurovascular bundle (deep peroneal nerve and the dorsalis pedis artery) lies lateral to the incision. The ankle joint is covered by an extensive fat pad that contains a venous plexus requiring partial cauterization.

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