First Study to Visually Capture Biofilm Structure of Retrieved Implants from Spine Patients with Pseudarthrosis

Elizabeth Hofheinz, M.P.H., M.Ed.

If seeing is believing, then researchers from the University of Toledo, Primus Super Speciality Hospital, the University of Southern California (USC) Spine Center, the Spine Center Cedars Sinai Medical Center, and the Department of Orthopaedics at the University of California, are “there.”

Given recent findings indicating that the association between pseudarthrosis and pedicle screw loosening often involves bacterial contamination, a multicenter team of researchers indicates that it set out to “visually capture the architecture of these undiagnosed infections, which have been described in other studies as biofilms on supposedly ‘aseptic’ screw loosening”

Their study, “High Prevalence of Biofilms on Retrieved Implants from Aseptic Pseudarthrosis Cases,” appears in Spine Surgery and Related Research.

The researchers examined explants from 10 patients undergoing revision spine surgery for pseudarthrosis. Each implant was fixed in glutaraldehyde solution and imaged thoroughly by using scanning electron microscopy and X-ray spectroscopy. Eight patient swabs from tissues surrounding the implants were sent for cultures to assess bacterial infiltration in tissues beyond the biofilm. Furthermore, the researchers analyzed the implants via energy dispersive x-ray spectroscopy. Implants involving a clinically diagnosed infection (current or previous) and/or mechanical failure of the implant due to falls/accidents were excluded.

Jeffrey C. Wang, M.D., Co-director of the University of Southern California, Spine Center, told OSN, “We are just starting to understand the biological issues that can arise from some patients with pseudarthrosis cases, and the potential for the formation of biofilms being either a potential consequence of a non-union, or even a potential contributing factor.”

The researchers were indeed able to capture the visual architecture of the biofilm on retrieved implants. They wrote, “A total of 77% of pseudarthrosis cases presented with loose pedicle screws, which were diagnosed by a preoperative computed tomography scan showing radiolucency along the screw track and were confirmed intraoperatively, and 72% of the cases showed biofilm on explants.”

“In the absence of the clinical presentation of infection, impregnated bacteria could form a biofilm around an implant, and this biofilm can remain undetected via contemporary diagnostic methods, including swabbing. Implant biofilm is frequently present in ‘aseptic’ pseudarthrosis cases.”

Dr. Wang: “Further research into this area is needed, along with surgeons understanding that there is likely some relationship that exists.”