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Realignment Surgery for Valgus Ankle Osteoarthritis


Indications

  • Physically active patients with lateral ankle joint degeneration associated with valgus malalignment (e.g., posttraumatic malalignment, ankle joint instability)

  • Lateral osteochondritis dissecans of the talus associated with valgus malalignment

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

Indications Pitfalls

  • Loss of >50% of tibiotalar joint surface (anteroposterior 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 with ankle fusion.

Indications Controversies

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

  • Tobacco use should be considered as a relative contraindication for supramalleolar osteotomy.

  • Operative technique (medial closing vs. lateral open wedge, ± fibula osteotomy) used for the correction depends on the extent of the deformity and soft tissue condition.

Examination/Imaging

  • Assessment of the patients gait and the entire 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. Evaluate to which a present deformity is correctable.

  • Ask the patient to go to tiptoe position and analyze the foot for varisation of the heel und supination of the foot.

  • A weight-bearing anteroposterior radiograph of the ankle, lateral and dorso-plantar radiographs of the foot, and a Saltzman hindfoot view are necessary to assess the nature and location of the deformity (supramalleolar, through the ankle joint, inframalleolar, or a combination). If a deformity at the level of the knee joint or the femur can not be excluded clinically, long leg radiographs are also necessary ( Fig. 51.1 ).

    FIG. 51.1

  • The medial distal tibial angle (angle between the tibial axis and the tibial joint surface) is measured on weight-bearing anteroposterior radiographs for assessment of the deformity. The required correction can be measured out of the radiographs 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.

  • Next to plane weight-bearing radiographs, (weight-bearing) computed tomography (CT) scans and magnetic resonance imaging (MRI) are not routinely required. However, they could be of value when assessing rotational malalignment, osteochondral lesions, and tendon disorders.

  • Combined single-photon emission and computed tomography (SPECT) scan has been found to be a valuable tool for assessment and staging of ankle osteoarthritis.

  • Distinction between congruent and incongruent joints is helpful in determining the type of osteotomy performed (tibia only vs. tibia and fibula).

  • The aim of surgical correction is to unload the lateral tibiotalar joint and talofibular joint. Most authors recommend an overcorrection of 3–5°.

  • Patients with an excessive heel valgus may need an additional calcaneus osteotomy to shift the heel contact point medially to the mid-diaphyseal tibial axis.

  • After ankle fracture, malunion of the distal fibula with shortening and external rotation may be the cause of the valgus deformity. An additional fibula osteotomy may be necessary in these cases.

  • Additional rotational or translational deformities must be taken into consideration when planning the osteotomy.

Treatment Options

  • Conservative treatment (i.e., pain medication, shoe modification, orthoses) should always be considered before surgery is performed.

  • Malalignment that is due to forces from the neighboring structures, such as unbalanced muscle forces, can be treated with physiotherapy or footwear modifications. Deforming forces, such as forefoot abnormalities, may require other surgical procedures than supramalleolar osteotomies.

  • An alternative surgical treatment is the medial calcaneal displacement osteotomy. Commonly, correction of any kind of malalignment is best performed at the level of the deformity.

  • Resurfacing of destroyed articular surfaces by TAR may allow for earlier weight bearing, but may not fully correct the deformity and instability and thus may fail in the case of an asymmetric wear pattern.

  • Ankle fusion may enable high activity, but compensatory movements of adjacent foot joints may cause degenerative osteoarthritis.

Surgical Anatomy

  • A medial or lateral approach to the distal tibia/fibula is used.

  • In the case of a medial approach, the great saphenous vein and the saphenous nerve usually lie anterior to the incision. The neurovascular bundle runs along the anterior border of the medial malleolus. Be also aware of the posterior tibial tendon, which lies immediately on the posterior aspect of the medial malleolus ( Fig. 51.2 ).

    FIG. 51.2

  • In the case of a lateral incision, take care of the sural nerve and the short saphenous vein. Both run dorsal to the line of incision and are usually not seen during this procedure. However, extended proximal dissection may require identification, exposure, and protection 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 ( Fig. 51.3 ).

    FIG. 51.3

Positioning

  • Medial approach: Supine, ipsilateral knee in slight flexion with a sandbag under the calf. A support can be placed on the opposite iliac crest to tilt the table away from the surgeon.

  • Lateral approach: Lateral decubitus position or supine with a sandbag under the buttock of the affected limb.

Positioning Pearls

  • More space for the surgeon is available if the operated leg is elevated with cushions or the opposite leg is lowered. In addition, lateral radiographs can be taken more easily.

Positioning Pitfalls

  • The surgeon should control the draping to ensure the appropriate implementation of the procedure.

Positioning Equipment

  • A radiolucent operating table

  • A tourniquet can be used to ensure optimal conditions during surgery

Positioning Controversies

  • In order to compare the corrected alignment of the foot and ankle intraoperatively, the contralateral ankle may also be draped.

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