Staged treatment of first metatarsal osteonecrosis using a custom titanium spacer for first metatarsophalangeal joint arthrodesis: A case report and literature review✰,✰✰,★

Purpose: Osteonecrosis of the first metatarsal is rarely seen in the current foot and ankle literature, but is commonly reported as a complication associated with sustained corticosteroid use. This case study presents our staged treatment of a patient who developed complications after repeat corticosteroid injections into the first metatarsophalangeal (MTP) joint for osteoarthritis secondary to hallux rigidus. Case Study: A 61 year old female was referred to the Foot and Ankle Service with a complaint of a painful bump at the dorsomedial aspect of the right first MTP joint following numerous corticosteroid injections to address underlying osteoarthritis. Plain radiographs revealed a large extra-articular soft tissue mass, significant erosion at the head of the first metatarsal, and overall appearance concerning for a possible malignant neoplasm. MRI showed mixed signal on T2 and T1, representative of a complex fluid collection with internal debris or blood products. Excision was recommended for pathology analysis. Procedures: Excision of soft tissue mass and partial excision of first metatarsal followed by a staged first MTP arthrodesis with custom titanium truss was performed without complication. Results: Surgical pathology was negative for malignancy and the patient went on to successful fusion following truss arthrodesis. She was able to return to regular shoe gear with pain-free ambulation. Analysis & Discussions: Osteonecrosis following regular corticosteroid use has been commonly reported in the literature, but to our knowledge there have been no recorded cases of osteonecrosis at the first metatarsal head following intra-articular injections for the treatment of hallux rigidus. In our case, a significant amount of necrotic bone was resected, leaving a large defect prior to arthrodesis of the 1st MTP joint which required custom titanium truss to be a successful adjunct in achieving a solid fusion mass.