Identification and Analysis of the Ankle Microbiome Using Next-Generation DNA Sequencing: An Observational Analysis

Abstract

Category: Ankle; Basic Sciences/Biologics Introduction/Purpose: Next-generation DNA sequencing (NGS) technologies have increased the sensitivity of bacterial cultures and has been used in other areas of orthopaedics to better understand the native microbiome of various joints. This study uses NGS to determine whether (1) a unique microbiome exists in human ankle tissues, (2) if components of the ankle microbiome impact patient outcomes, and (3) whether microbes found on the skin are a normal part of the ankle microbiome. Methods: A prospective study recruited 32 patients undergoing total ankle arthroplasty (TAA, n=23) or ankle arthrodesis via an anterior approach (n=9) during 2020-2021 with one of two fellowship-trained foot and ankle surgeons at an academic medical center. During the operation, the surgeon would swab five layers of the ankle for analysis at a CLIA-licensed molecular diagnostic laboratory: skin (n=32), retinaculum (n=31), tibialis anterior tendon (n=31), joint capsule (n=31), and distal tibia (n=32). Demographics, medical comorbidities, surgical indication, postoperative complications, and readmission and reoperation rates were collected from patient records. Results: Of the 157 swabs sent for NGS, 19 (12.1%) indicated 27 bacteria were present (positive), while the remaining 138 (87.9%) had no bacteria present (negative). The most common organisms were Cutibacterium acnes, present in 11 ankles (34.4%), and Staphylococcus epidermidis, present in 3 ankles (9.4%). The most bacteria were found in the retinaculum (29.6%). No PROM nor follow-up duration was associated with the presence of bacteria, or the number of bacteria or affected layers. Similarly, complication (positive=18.2%, negative=23.8%; p=1.000), nonunion (positive=0.0%, negative=28.6%; p=1.000), infection (positive=0.0%, negative=4.8%; p=1.000), 90-day readmission (positive=0.0%, negative=4.8%; p=1.000), and reoperation (positive=0.0%, negative=4.8%; p=1.000) rates did not differ if a subject’s NGS profile was positive or negative. Conclusion: This study found that C. acnes and S. epidermidis were most commonly found in the ankle microbiome, with C. acnes being present in 34% of ankles. There was no difference in complication rates between patient with and without positive bacterial cultures following TAA or ankle arthrodesis.