Influence of Staphylococcus epidermidis biofilm on the mechanical strength of soft tissue allograft. Issue 2 (19th May 2022)

• Record Type: Journal Article
• Authors: Sorensen, Hanna H.; Magnussen, Robert A.; DiBartola, Alex C.; Mallory, Noah T.; Litsky, Alan S.; Stoodley, Paul; Swinehart, Steven D.; Duerr, Robert A.; Kaeding, Christopher C.; Flanigan, David C.
• Is Part Of: Journal of orthopaedic research. Volume 41:Issue 2(2023)
• Page Start: 466
• Page End: 472
• Publication Date: 2022-05-19
• Subjects: ACL reconstruction -- graft failure -- infection -- Staphylococcus epidermis; Orthopedics -- Periodicals; Musculoskeletal system -- Periodicals; 616.7
• DOI: 10.1002/jor.25360
• Languages: English
• ISSNs: 0736-0266

Abstract

Abstract: We sought to determine the impact of bacterial inoculation and length of exposure on the mechanical integrity of soft tissue tendon grafts. Cultures of Staphylococcus epidermidis were inoculated on human tibialis posterior cadaveric tendon to grow biofilms. A low inoculum in 10% growth medium was incubated for 30 min to replicate conditions of clinical infection. Growth conditions assessed included inoculum concentrations of 100, 1000, 10, 000 colony‐forming units (CFUs). Tests using the MTS Bionix system were performed to assess the influence of bacterial biofilms on tendon strength. Load‐to‐failure testing was performed on the tendons, and the ultimate tensile strength was obtained from the maximal force and the cross‐sectional area. Displacements of tendon origin to maximal displacement were normalized to tendon length to obtain strain values. Tendon force‐displacement and stress‐strain relationships were calculated, and Young's modulus was determined. Elastic modulus and ultimate tensile strength decreased with increasing bioburden. Young's modulus was greater in uninoculated controls compared to tendons inoculated at 10, 000 CFU ( p = 0.0011) but unaffected by bacterial concentrations of 100 and 1000 CFU ( p = 0.054, p = 0.078). Increasing bioburden was associated with decreased peak load to failure ( p = 0.043) but was most significant compared to the control under the 10, 000 and 1000 CFU growth conditions ( p = 0.0005, p = 0.049). The presence of S. epidermidis increased elasticity and decreased ultimate tensile stress of human cadaveric tendons, with increasing effect noted with increasing bioburden. Clinical Relevance: Understanding the impact of subclinical and chronic infection on mechanical strength following ACLR may reduce graft failure and prolong the integrity of the reconstruction.