Medial-sided bony procedures: why, what, and how?

The adult acquired flat foot deformity is a common clinical entity; rupture or incompetence of the posterior tibial tendon is a frequent cause. The natural history is characterized by progressively worsening deformity and early recognition is important. Nonoperative treatment can alleviate symptoms and control progression in nearly all stages of the disease. Should this fail to control symptoms or prevent progression of deformity, operative intervention should be considered. In stage I disease, exploration and debridement, with or without FDL tendon transfer, is a viable option. In stage II disease, the PTT becomes elongated and the medial soft tissues become attenuated. Exploration and debridement of the PTT is performed, but frequently a FDL tendon transfer or side-to-side anastomosis is required. It has been shown that soft tissue procedures alone may fail to correct deformity and this can lead to deterioration of results over time. Combined procedures, including soft tissue reconstructions to restore PTT function and bony procedures to correct deformity, have become popular. When the PTT is intact and degeneration or elongation is minimal, as in stage I or early stage II disease, reconstruction of the medial column with advancement of an osteoperiosteal flap based on the PTT insertion, combined with selective arthrodeses of the medial column, may be considered. These procedures have been well described for the treatment of symptomatic flexible flat foot in children and adolescents but experience in adults is lacking. Although it may be theoretically possible to passively correct hindfoot valgus with these procedures, it seems prudent to limit the indications to patients who have early disease accompanied by an isolated midfoot sag. In more advanced stage II disease, correction of deformity with a tendon transfer combined with a medial displacement calcaneal osteotomy or a lateral column lengthening is currently recommended. This allows for correction of deformity while sparing the hindfoot joints, which may be particularly important in young or active patients. Short-term studies showed excellent results, but long-term results are lacking. In stage III disease, in which the deformity is fixed, arthrodesis is the procedure of choice. Isolated talonavicular arthrodesis has been shown to correct nearly all aspects of the deformity with long-lasting results. This procedure results in nearly complete lack of hindfoot motion and may predispose the patient to adjacent joint arthrosis. In a patient who has stage III disease with arthrosis confined to the talonavicular joint, isolated talonavicular arthrodesis may be considered. This clinical situation is rare, and, in most patients, a triple arthrodesis is probably preferred. If residual deformity is present after these procedures, it must be addressed. Residual medial column instability may be addressed by adding a selective arthrodesis of the naviculo-cuneiform or first metatarsocuneiform joint, whereas residual forefoot varus or supination may be addressed with selected midfoot fusions with or without a cuneiform osteotomy.