Coralline hydroxyapatite bone graft substitute in hindfoot surgery

BACKGROUND: Coralline hydroxyapatite bone graft substitute material is created by the conversion of the calcium carbonate structure of coral into hydroxyapatite. The microstructure of the material resembles cancellous bone and provides an osteoconductive scaffold for bone ingrowth. The use of this material is reported in the orthopedic oncology and trauma literature. Short-term reports in foot procedures have been reported. METHOD: A retrospective review identified 10 patients who had undergone hindfoot arthrodesis with coralline hydroxyapatite bone graft. The charts were reviewed for outcomes, operative complications, and time to union. Nine of the 10 patients were available for additional examination. RESULTS: The average followup was 6 years. There were three complications. One patient had sural nerve numbness with partial resolution which was unrelated to the graft material. A rheumatoid patient on methotrexate and prednisone developed a deep wound infection 9 months after surgery. One patient had a nonunion of the talonavicular joint. Eight of the 10 patients reported good or excellent results. Radiographs continued to demonstrate the presence of the graft material at 6 years. Radiographs showed extrusion of the graft from the joint in all patients. No patient had symptoms from the extruded material. DISCUSSION: Coralline hydroxyapatite bone graft substitute appears to be a clinically effective material for use in foot procedures. No adverse events could be linked to the graft material. The graft material is difficult to contain and extrusion was present in all patients. The slow resorption is a concerning characteristic of the graft material. At 6-year followup, the continued presence of the material has not shown any adverse effect.