Subtalar Distraction Bone Block Arthrodesis for Calcaneus Fracture Malunion

Abstract

Intra-articular calcaneus fractures are associated with a high rate of malunion resulting in hindfoot and ankle impingement, peroneal tendinitis, sural neuritis, arthritis, hindfoot varus or valgus deformity, loss of hindfoot height, and resulting gastrocnemius-soleus complex weakness and gait dysfunction. These issues can arise whether the patient’s injury is treated conservatively with non–weight-bearing precautions, neglected/missed, or treated surgically with open reduction and internal fixation. The sequelae of calcaneal malunions can arise early or late in this process. For patients undergoing subtalar arthrodesis following calcaneus fracture malunion, the use of a bone block wedge can assist with achieving a stable ,well-aligned, pain-free hindfoot. Patient selection, preoperative planning, careful surgical technique, and compliance with postoperative care pathways are critical to optimize patient outcomes and healing of this complex reconstruction. Recent evidence supports the utility of weight-bearing CT to assist with preoperative planning for subtalar arthrodesis. Wedges used in subtalar distraction arthrodesis include bulk autograft (tricortical iliac crest), allograft (pre-fashioned or intraoperatively fashioned wedges from femoral head allograft or other source), and metallic wedges. These wedges are typically secured with screws spanning and compressing the arthrodesis site, which is filled with a mixture of concentrated bone marrow aspirate, bone growth factors, and allograft bone. Concomitant procedures may be indicated to ensure the overall success of the procedure, such as extra-articular, calcaneal osteotomy for additional realignment purposes and/or arthrolysis. A review of the literature shows high rates of union following subtalar bone block arthrodesis with improved functional outcomes. Our preferred technique for a bone block distraction subtalar arthrodesis, described herein, includes the use of an allograft wedge. Ongoing advances, such as the development of novel materials and structures for use in subtalar bone block arthrodesis, but most importantly, the incorporation of weight-bearing CT technology and potential for preoperative CT navigation to make this procedure more predictable, are all important areas for further exploration and future research. Level of Evidence: Level—4.