CHAPTER 19 Complex Ankle, Subtalar, and Triple Fusions
Arthroscopic ankle arthrodesis can be extended to include cases with some bone deformity or extensive osteophyte formation if the surgeon is patient and experienced with simpler cases.1 These cases should be performed after the surgeon has achieved proficiency with arthroscopic ankle and subtalar fusion. When the soft tissue envelope is compromised, the additional time required for the more complex operation may be justified by the prevention of soft tissue complications.
NORMAL AND PATHOLOGIC ANATOMY
Anatomic considerations are addressed in Chapter 17. Talonavicular arthritis with deformity or subtalar arthritis is a clear indication for triple arthrodesis. Isolated talonavicular arthritis may be amenable to isolated talonavicular fusion. However, an isolated talonavicular fusion is more likely to progress to a nonunion because there may be motion across the joint despite two screws being used for fixation. Because no significant gain in motion is achieved with an isolated talonavicular fusion compared with a full triple arthrodesis, a triple arthrodesis may be preferable because a larger fusion mass is obtained and better stabilization performed.
PATIENT EVALUATION
History and Physical Examination
Degree of Disability
Patients should be assessed for their degree of disability. Their walking tolerance and standing tolerance are good indicators of disability. They might have had to stop work because of the hindfoot pain. Sports might have been permanently discontinued or restricted due to pain or instability. Before treatment, the degree of disability should be outlined to determine success of intervention.
TREATMENT
Complex Arthroscopic Ankle Fusion
Bone Deformity
When there is erosion of the medial or lateral side of the joint, a standard arthroscopic fusion can be performed and augmented by correction of the deformity by sculpting of the prominent side of the joint with a burr to allow correction of the varus or valgus plane deformity. Removal of some of the tip of the medial or lateral malleolus may be required to allow joint compression. The edge of the bone deformity often is located within the joint and can indicate where to start applying the burr to reduce the deformity. The degree of bone removal can be estimated using intraoperative fluoroscopy.