Session VIII - Foot and Ankle

Subtalar Fusion for Post-Traumatic Arthritis Secondary to Calcaneal Fractures

Samuel Flemister, MD, Anthony F. Infante, Jr., DO, Michael Sirkin, MD, Roy Sanders, MD

Florida Orthopaedic Institute, Tampa, Florida, USA

Purpose: To evaluate and compare the subtalar fusion rate using different bone graft materials in patients with post-traumatic arthritis secondary to isolated calcaneal fractures.

Materials and Methods: Between 1989 and 1996, 82 hindfoot fusions in 75 patients were performed by the senior author secondary to post-traumatic arthritis. Of these, 58 patients with 64 post-traumatic arthritic subtalar joints secondary to isolated calcaneal fractures were treated with subtalar fusions and make up this study population. Of the 64 fractures, 41 were referred after failure of nonoperative treatment or limited internal fixation and had developed Sanders type II or type III calcaneal malunions. Fourteen had failed open reduction and internal fixation (ORIF) for Sanders type II or III calcaneal fractures, and 9 had Sanders type IV displaced calcaneal fractures treated with ORIF and primary fusion. Fusions for malunions or failed ORIF were performed utililizing a Seattle modified Kocher incision, removal of articular cartilage only using a sharp periosteal elevator and 2 retrograde 6.5, 7.0 or 7.3 cannulated cancellous lag screws compressing the subtalar joint. Primary fusions were performed utilizing either a 1 or 2 compression screw technique. Calcaneal Malunions - 27/41 received local graft from the lateral wall exostectomy alone, either for an in situ or bone block fusion, while 11/41 received iliac crest bone graft (ICBG), 1 received allograft alone, 2/41 received a combination of lateral wall exostectomy and allograft because of insufficient local graft for a bone block fusion. ORIF - 12/14 received ICBG and 2/14 received allograft only. Primary fusions - 4/9 received ICBG alone, 3/9 allograft alone and 2/9 ICBG with supplemental allograft. All patients were treated in a splint postoperatively, followed by a short leg non weight bearing cast for 8-10 weeks and a walking cast or boot for 4 weeks. All patients were analyzed for union, surgical complications and for length of hospitalization.

Results: One Sanders type IV calcaneus that underwent delayed ORIF and primary fusion required amputation for uncontrolled infection. This left 63 fusions for evaluation. 62/63 fusions united within 4 months, for a union rate of 98.4%. The union rate did not vary between patients with different primary treatments, nor did it vary with the use of different graft material. Complications included 1 nonunion in a calcaneal malunion, and 2 wound complications requiring debridement and IV antibiotics - one in a Sanders type IV fracture, and one in an insulin dependent diabetic patient failing initial ORIF. Length of hospital stay averaged 2.4 days for those fusions performed with allograft or local graft. For those patients receiving an ICBG, the average length of hospitalization was 3.7 days, with only 4/23 patients staying 48 hours or less.

Discussion and Conclusions: Based on our data, a subtalar fusion for post-traumatic arthritis after a calcaneal fracture will unite within four months of the index procedure, regardless of the primary treatment or the graft material used, if the articular cartilage is debrided and the subtalar joint compressed using large fragment cancellous lag screws. Furthermore, iliac crest bone is not needed for graft material when performing a subtalar fusion. The advantages of this include lack of donor site morbidity and decreased post-operative pain. Finally, in situ subtalar fusions performed with local graft or allograft, articular cartilage debridement and cannulated cancellous large fragment lag screws result in a decreased length of hospital stay thereby reducing overall costs to the insurer.