Preliminary Results and a Treatment Algorithm for Osteomyelitis of the Distal Tibia and Talus

Abstract

Category: Hindfoot; Ankle Introduction/Purpose: Management of hindfoot osteomyelitis involves eradication of infection, deformity correction, and bony stabilization in the setting of bone loss and poor bone quality. This case series of 20 patients presents a two-stage technique: debridement, deformity correction, joint surface preparation, intramedullary reaming with antibiotic-impregnated polymethyl methacrylate rod and ring external fixation, followed by a second stage of external fixator removal and exchange of antibiotic rod for definitive hindfoot fusion rod. The purpose of the study is to highlight techniques and preliminary results that can improve the success of obtaining stable fixation, remission of infection and ultimately fusion. Techniques highlighted are ring fixator placement, antibiotic rod formulation, intramedullary canal preparation, rod exchange and use of blocking screws to enhance compression and axial loading of the fusion. Methods: Twenty patients were treated with this two-stage protocol. The most common indication was post-traumatic osteomyelitis followed by neuropathic (Charcot) joint. All were treated with an initial debridement of nonviable tissue including osteomyelitic bone. The tibiotalar and talocalcaneal joint surfaces were prepared for fusion at the initial debridement. Provisional stabilization and compression were obtained using a ring external fixator for patients without rotational stability. The polymethyl methacrylate-antibiotic impregnated rod (PMMA with gentamycin and vancomycin) was introduced through the calcaneus, talus, and the intramedullary space of the tibia. The patients were kept in the fixator until the skin was healed and all incisions were dry. At this point, the fixator was removed, and the antibiotic rod was exchanged for the definitive hindfoot fusion rod. Results: Cultures were positive for Staphylococcal or Streptococcal species in 60% of cases, Fingeoldia magna 10%, Cutibacterium Acnes 2%, and Gram-negative organisms in 30%. On average patients spent 80 days in the fixator while wounds were healing, and were receiving systemic antibiotics. One patient died while in the frame. There have been no amputations in the series. Of the patients that have completed the protocol, all have gone on to either bony fusion or stable fibrous union. All are able to walk unaided and 25% used an AFO to control and protect the foot and equalize leg length. Secondary procedures are described. Conclusion: This technique of staged fusion for hindfoot osteomyelitis offers the following advantages. The first stage involves thorough debridement and deformity correction. Oftentimes, there is extensive scarring, and the soft tissue envelope is not conducive to internal fixation. This technique allows the soft tissues to heal before placing the definitive internal fixation. It also allows for graduated compression at the fusion site with the ring fixator. The antibiotic rod not only delivers high concentration of local antibiotics, but it prevents deformity recurrence during the compression phase. The definitive rod provides support of pathologic bone and maintains deformity correction.