Use of Antibiotic Spacer with Syndesmotic "Fin" for Treatment of Septic Ankle Joint: Two-Stage Approach or Definitive Management?

Abstract

Septic ankle joint following orthopedic surgery is a rare but limb-threatening complication that requires emergent multi-modal management. Traditionally, spacers serve as stage one of a two-stage approach involving deep infections seeding to a joint. However, a paucity of literature exists regarding the outcomes and longevity of antibiotic spacers in patients who are poor candidates for a subsequent reoperation. We present a case of an 89-year-old female who sustained an open pilon fracture treated with external fixation, and a subsequent open reduction internal fixation following a fall from a height. The patient developed surgical site dehiscence that progressed to a septic ankle joint, confirmed via single-photon emission computed tomography and a three-phase bone scanning. The patient underwent a debridement with operative wash-out and fashioning of a methylmethacrylate antibiotic spacer containing 1 g of vancomycin and 1.2 g of tobramycin. This was positioned in the ankle joint with an adapted "fin" extending anteriorly and proximally in the tibiofibular syndesmosis, to provide stability to the spacer, and potentially increase its longevity interpositionally. With aggressive local wound care and an oral antibiotic course, the patient proceeded to complete reepithelialization of the sinus tract 6 weeks postoperatively. Serial imaging and computed tomographic scan confirmed a well-seated spacer, without evidence of migration or extrusion, 14 months after surgery. Outcome data regarding cement ankle arthroplasties are extremely limited. Retrospective case series have quantified average retention anywhere from 6 to 62 months with varying techniques. However, in the setting of multiple comorbidities, or other factors making a patient a poor candidate for reoperation, an antibiotic spacer may serve as a definitive treatment for such an infection with satisfactory outcomes. We believe the presented method, with use of a proximal fin articulating in the tibiofibular syndesmosis, not only improves implant retention, but also, maintains a functional, plantigrade ankle joint.