Suture-related pseudoinfection after total hip arthroplasty

Absorbable sutures are widely used for wound closure after total hip replacement. Here we present two cases of suture-related foreign-body reaction that perfectly mimicked a periprosthetic joint infection, with sterile abscess formation and physical and laboratory signs of inflammation acutely presenting 7-8 weeks after surgery, at the time of suture absorption. Both recurred with analogous timing after irrigation and debridement, likely due to re-using the same suture material. Multiple negative microbiological samples and positive histological samples showing a foreign-body reaction are the fundamental steps towards the diagnosis of a suture-related pseudoinfection (SRPI). Only three other cases have been reported to date, but the recurrence, together with the self-healing course after relapse, represents a completely novel feature and possibly the strongest demonstration of the supposed aetiopathogenesis. The knowledge of this possible complication leads to some clinical implications: all potential periprosthetic joint infections should routinely undergo not only microbiological but also histological sampling; caution should be used when recommending prosthesis exchange for potential infections occurring in the time range of suture absorption; lastly, if SRPI is suspected, a suture with low propensity to induce foreign-body reactions should be chosen after irrigation and debridement and the volume of absorbable material left in the wound should be as small as possible.