Infection Following Lower Limb Transfemoral and Transtibial Osseointegration Surgery: A Single-Centre Retrospective Review

Lower limb osseointegration (OI) surgery is a novel surgical procedure performed on patients with lower extremity amputations at a limited number of US centers. Traditional socket-based prostheses can negatively impact quality of life and carry many functional restrictions. The OI surgical procedure is performed in one or two stages, which involves implanting a stem into either the femur or tibia depending on the level of the amputation, and the creation of a stoma through which the external prosthesis attaches to said stem. The stoma lacks a physiologic skin seal and creates a portal of entry for bacteria directly to the underlying osseous structures, soft tissue, and implant. As such, infection rates for osseointegration surgeries outpace those of other orthopaedic surgical procedures. More information is needed regarding the microbiological profile of these infections, infection-related outcomes, and risk factors for these patient cohorts. Our study aims to describe the microbiology and clinical characteristics of lower limb OI infections, to assess outcomes in those with lower limb OI infections, and assess if pre-operative antibiotic choice predisposes to OI related lower limb infection. An institutional review board (IRB) approved retrospective analysis was performed on all patients who underwent either transtibial or transfemoral lower limb osseointegration surgery at our institution from September 16th, 2019 through September 12th, 2024. Demographic, medical, operative, and outcomes data were collected for all patients in the cohort. Twenty-six infection events occurred in twenty-four unique patients out of eighty-one total patients who met inclusion criteria, for an infection rate of 29.6%. Patients were followed for a minimum of twelve months, with a range of follow up from 12 to 71.9 months. Twelve infection events were monomicrobial (46.1%), and seventeen (65.4%) had gram positive organisms only. The most common type of infection was skin and soft tissue or stoma-related, with eleven (42.3%). Nineteen (73.1%) infection events required a return trip to the operating room. Twenty-three events (88.5%) maintained retention of the osseointegrated implant. This study helps to advance the knowledge base surrounding osseointegrated lower limb implant infections and describes the predominantly gram-positive microbiological characteristics and outcomes of those infections. Though there is a high infection rate, the outcomes are generally good with a high implant retention rate. Additionally, we found that the use of appropriate pre operative anti-microbials with cefazolin is protective against developing infection. Finally, this study highlights the need for multi-disciplinary management of these patients.