Methylene Blue Infiltration As a Method for Distinguishing Superficial and Deep Infections

Background There are no established objective methods to reliably differentiate between superficial and deep infection in the setting of total hip arthroplasty. We employed a technique of distinguishing superficial and deep infections by infiltrating methylene blue to a prosthetic hip during infection workup to determine its effectiveness and to characterize its utility in defining the joint cavity where deep debridement is required. Methods An analysis was conducted on 35 patients who preoperatively received an injection of methylene blue under radiological guidance to their total hip arthroplasty. Where established periprosthetic joint infection (PJI) criteria were not met, without signs of methylene blue beyond the deep fascia, the infection was considered superficial, and debridement remained superficial to the deep fascia. Where diagnosis of PJI was confirmed preoperatively or the presence of methylene blue in the wound cavity confirmed deep contamination, the prosthesis was addressed with methylene blue staining defining the joint cavity as a guide for debridement. Results There were 11 patients who had no methylene blue extrusion into the superficial compartment and did not meet PJI criteria. Eight patients failed to meet PJI criteria preoperatively, but had extrusion of methylene blue, confirming a deep infection intraoperatively. There were 16 patients who met PJI criteria preoperatively with methylene blue acting as a visual guide to the joint space. Conclusion Infiltrating methylene blue in a prosthetic hip is useful in differentiating between superficial or deep infections where PJI workup is indeterminate. Where deep infection is present, its utility in defining the joint cavity may be advantageous.