Session II Foot and Ankle

Subtalar Bone Block Fusion in the Management of Symptomatic Subtalar Malunion

Charles N. Cornell, MD, Martin O'Malley, MD, Michael Diminick, MD, Jean O'Doherty, MA

Hospital for Special Surgery, New York City, NY

Hypothesis: The purpose of this retrospective analysis was to review the outcome of distraction subtalar fusion for the treatment of painful malunion of calcaneal fractures.

Conclusion: Subtalar bone block fusion is an effective salvage procedure for calcaneal malunion and post-traumatic subtalar arthritis.

Materials and Methods: Since 1991, all patients with symptomatic calcaneal malunions with subtalar arthritis and loss of calcaneal height presenting to our service have been managed with a bone-block, distraction subtalar fusion using the technique described by Carr et. al.* During this period twenty-three patients (15M, 8F) have been treated with this procedure and have been followed for at least two years ranging from two to five years. Results were retrospectively reviewed radiographically, and by applying the Foot and Ankle Society functional hindfoot scale. A visual analogue scale for pain was also completed by the patients. Radiographic parameters measured on pre-op, post-op and final follow-up Xray included talocalcaneal declination angle, talocalcaneal height, successful subtalar fusion, and development of talar bossing and anterior ankle osteophyte formation.

Results: Twelve patients completed the questionnaire. At the time of follow-up 6 of 12 patients scored excellent results with no complaint of pain using the AOFAS rating system and visual analogue scale for pain. An excellent rating implies no limitations in walking with excellent calf strength and ankle function. Of the five poor results two patients complained of persistent pain from sural neuroma, two patients have persistent discomfort from associated injuries and deformity of the os calcis and one patient has a nonunion of the subtalar fusion. Two of the five poor results required screw removal. Hardware removal has not been required in 22 patients. Radiographic analysis verified solid fusion in 23 of 29 patients. The average increase in talocalcaneal declination angle was 4 degrees (0-10) and the increase in talocalcaneal height averaged 6 mm (5-20 mm).

Discussion: Subtalar distraction fusion is an effective treatment for symptomatic calcaneal malunion with subtalar arthritis and shortening. Fusion is predictably reliable as is relief of pain and restoration of excellent hindfoot strength and function. Patient satisfaction is high. Poor results occur when sural injury, and nonunion result. Although improved, patients with persistent calcaneal deformity have persistent disability.

* Carr JB, Hansen ST, Benirschke SK: Subtalar Distraction Bone Block Fusion for Late Complications of Os Calcis Fractures. Foot and Ankle 9:81-85 1988