Chapter 39 Lateral Ankle Reconstruction
Ankle Instability
• Chronic lateral ankle instability is defined as instability and associated symptoms for greater than 6 months. These signs and symptoms are caused by either mechanical or functional instability.
• Mechanical instability, referred to as laxity, is defined as ankle movement beyond the physiological limit of the ankle’s range of motion (ROM).
1 True mechanical instability may be demonstrated using clinical tests, including the anterior drawer, the talar tilt, or diagnostically using a wide variety of radiographic tests, including stress radiography, magnetic resonance imaging (MRI), computed tomography (CT scan), and bone scan.
• Functional instability, a term first defined by Freeman et al., is a subjective feeling of “giving way” or evidence of recurrent, symptomatic ankle sprains. As well documented, mechanical instability is not a reliable indicator of a functionally unstable ankle.
• Studies have shown that joint position sense and kinesthesia are greatly diminished in individuals with chronic ankle instability (CAI), which, in turn, leads to repetitive lateral ankle sprains. Other proprioceptive deficits may be accountable for these levels of instability.
• Additional contributing factors leading to functional instability include deficits in center of pressure excursion measures, postural stability, ROM, and invertor and evertor muscles strength.
• The focus of conservative rehabilitation for this population has been placed on challenging and regaining postural-control strategies, in addition to strengthening, flexibility, and regaining ROM.
• The 10% to 20% of individuals who have functional instability, with or without true mechanical instability, may require surgical intervention. These individuals have failed conservative treatment with guided physical therapy and are still having subjective complaints and recurrent incidents of instability.
• More than 50 surgical procedures have been described to treat lateral ankle instability. The surgical procedures for treating this pathology may be described as anatomical or nonanatomical.
Surgical Overview
• The ATFL resists inversion of the talus within the ankle mortis (talar tilt). The CFL acts as a restraint against subtalar inversion and thereby indirectly acts as a restraint for talar tilt. Without these restraints the ankle will be mechanically unstable.
• Anatomical repairs involve the ATFL and the CFL being imbricated and sutured. In cases where the ATFL and CFL tissues are obliterated, ligament augmentation may also be performed, using fascia lata, plantaris tendon, Achilles tendon, or allograft.
• The nonanatomical procedures are checkrein and tenodesis procedures using the peroneus brevis tendon.
• A tenodesis is the procedure of choice when an individual has general ligamentous laxity, has failed a modified Broström-Gould procedure, is an obese individual, or a direct repair is not possible because of chronic, repetitive trauma.
• Because all of these tenodesis procedures somewhat change the biomechanics of the subtalar joint, instability may be a complication for any of the tenodesis surgical procedures. Subjective complaints of instability following anatomical procedure tend to be less prevalent (0% to 3%).
• In 1966, Broström repaired the ATFL and CFL by attenuating and shortening the ATFL and CFL ligaments. This allowed for isometry of the ligaments as well as full ROM at the talocrural and subtalar joints. However, this procedure had a high rate of subtalar instability.
• In 1980, Gould et al. addressed this instability by developing the modified Broström procedure, whereby the extensor retinaculum was sutured to the anterior aspect of the fibula.
• The surgical procedure entails the foot being placed in a vertical or slightly internally rotated position.
• A curvilinear incision is made anteriorly to the distal fibula, stopping at the peroneals. Care must be taken because the sural nerve lies just below this incision over the peroneal tendons.
• The joint capsule is dissected along the anterior border of the lateral malleolus. The ATFL lies within the joint capsule, and the CFL lies deep to the capsule. Once both structures are identified, the repair can be made.
• The final phase is to attach the posterior portion of the extensor retinaculum to the distal fibula via sutures passed through holes in the fibula.
• This type of procedure reinforces the repair as well as limits inversion. This limitation of inversion is considered an acceptable outcome of the procedure given that instability was the initial pathology being corrected.
• The patient is placed in a short leg cast or bivalve cast and is non–weight-bearing following surgery.
Rehabilitation Overview
• Rehabilitation following a modified Broström procedure begins immediately postoperatively with gait training, patient education, and a home exercise program.
• Once active range of motion (AROM) is allowed, special care must be taken in limiting forces into inversion through the earliest phase of the healing process. Excessive tensile forces on the repair could potentially disrupt the repair.
• Formal physical therapy is initiated 6 weeks following surgery.
1 The patient bears weight as tolerated in an Aircast and uses either a cane or crutches as an assistive device.
• During the initial physical therapy outpatient evaluation, it is necessary to assess for intrinsic mechanical factors, including hind foot varus or generalized ligamentous laxity, because this will affect postoperative stresses on the repair as well as overall treatment approaches.
• It is important to note that most of the research and literature supporting this proposed guideline is relative to functional ankle instability (FAI). Lateral ankle reconstruction and FAI are comparable in their philosophies.
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