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C H A P T E R 66

Supramalleolar Osteotomy with Internal Fixation: Perspective 2

Markus Knupp and Beat Hintermann

DEFINITION

IMAGING AND OTHER DIAGNOSTIC STUDIES ■ Weight-bearing radiographs of the entire foot, the ankle, the tibial shaft (full-length radiographs), and the Saltzman hind- foot view are necessary to assess the nature and location of the deformity. Unless deformity at the level of the knee joint or the femur can be excluded clinically, whole lower limb radiographs are obtained. ■ Next to conventional radiography, computed tomography (CT) and magnetic resonance imaging are not routinely required. However, they could be of value when assessing rotational malalignment, osteochondral lesions, and pero- neal tendon disorders or evaluating the aspect of the liga- ment insufficiency. ■ Combined single-photon emission and conventional com- puted tomography (SPECT-CT) has been found to be a valu- able tool for the assessment and staging of osteoarthritis in asymmetric osteoarthritis of the ankle joint.

■ A supramalleolar osteotomy is an osteotomy at the level of the distal tibia with or without osteotomy of the fibula. ■ The correction is intended to normalize altered load distribu- tion across the joint and may be indicated in cases of asym- metric osteoarthritis, malunited fractures of the distal tibia, osteochondral lesions, and recurrent instability with deformity.

ANATOMY

■ Trauma and neurologic disorders leading to varus or valgus alignment around the ankle joint predispose to asymmetric joint load. ■ This causes cartilage wear, in particular in the presence of associated ligamentous instability and muscular imbalance.

PATHOGENESIS

■ Various conditions such as neurologic disorders, congenital and acquired foot deformities, posttraumatic malunions, and instability may be associated with malalignment of the ankle joint complex.

DIFFERENTIAL DIAGNOSIS

■ Symmetric or end-stage osteoarthritis ■ Muscular imbalance (eg, in neurologic disease) ■ Forefoot-driven hindfoot deformities

NATURAL HISTORY

■ Malalignment of the hindfoot may result from bony defor- mities above or below the level of the ankle joint. ■ Ligamentous instability or muscular imbalance of the ankle or the adjacent joints may be a contributing or even an ini- tiating factor in the natural history of malalignment around the ankle joint.

NONOPERATIVE MANAGEMENT

■ Asymptomatic, moderate malalignment usually is treated conservatively. ■ Malalignment that is due to forces from the neighboring structures, such as plantarflexed first metatarsal or unbal- anced muscle forces can be treated with physiotherapy or shoe wear modifications. Deforming forces, such as forefoot abnormalities or muscular imbalance, may require surgical procedures other than supramalleolar osteotomies. ■ Recommendations whether surgical or conservative therapy should be aimed for in asymptomatic but severe malaligned hindfeet are controversial. Because the deformity is likely to lead to excessive wear, surgery should be considered. ■ An alternative surgical treatment is the calcaneal displace- ment osteotomy (medial or lateral). Commonly, however, correction of malalignment is best performed at the level of the deformity.

PATIENT HISTORY AND PHYSICAL FINDINGS

■ A thorough medical history should be taken.

■ Systemic diseases such as diabetes mellitus (Charcot ar- thropathy), rheumatoid arthritis, and neurovascular dis- orders need to be assessed carefully. ■ Tobacco use should be considered a relative contraindica- tion to supramalleolar osteotomy. ■ Disorders that alter the bone quality and healing ca- pacity (medication, osteoporosis, age) should be assessed carefully. ■ Physical examination should include the following: ■ Drawer test and talar tilt test to assess ankle joint stability ■ Assessment of the inversion and eversion force to exclude peroneal tendon insufficiency

SURGICAL MANAGEMENT

■ Supramalleolar osteotomies are divided into opening/closing wedge osteotomies and dome-shaped osteotomies. ■ Ideally, the correction is carried out at the center of rotation of angulation (CORA), preferably in the metaphyseal bone.

■ Subtalar range of motion

■ Coleman block test to exclude a forefoot driven hindfoot varus

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