Soft Tissue Reconstruction Does Not Compromise Infection Control in Chronic Knee Periprosthetic Joint Infection Treated with Two-Stage Exchange Arthroplasty Despite Increasing Complexity

The role of soft tissue reconstruction in infection control of knee periprosthetic joint infection (PJI) treated with a two-stage exchange strategy remains controversial. This retrospective observational study analysed consecutive patients with chronic knee PJI managed with a two-stage protocol between 2010 and 2023, comparing outcomes between cases requiring flap-based soft tissue reconstruction and those achieving primary closure. A total of 118 patients with a minimum follow-up of 24 months were included. Forty patients (33.9%) required soft tissue reconstruction (STR), including 25 pedicled medial gastrocnemius flaps and 15 anterolateral thigh (ALT) microsurgical free flaps. Patients requiring STR showed greater baseline complexity, with a higher number of previous surgical procedures (3.03 vs. 2.08; p = 0.0057) and a higher prevalence of diabetes mellitus and sinus tracts. Despite this, infection control was superior compared with non-reconstructed cases (100% vs. 88.5%; p = 0.029). Within the STR group, both pedicled and microsurgical techniques achieved complete infection eradication; however, ALT flaps were associated with higher complication rates (46.7%), with partial flap necrosis being the most frequent event. The use of microsurgical reconstruction increased progressively over time, reflecting growing reconstructive complexity. Formal soft tissue reconstruction does not compromise and may facilitate infection control within a multidisciplinary pathway.