Strategic medial gastrocnemius flap in two-stage revision knee arthroplasty for periprosthetic joint infections: Outcomes and costs in a matched cohort.

Abstract

Periprosthetic joint infection (PJI) after total knee arthroplasty (TKA) remains one of the most morbid and expensive complications. Although gastrocnemius flap coverage is traditionally reserved for salvage, its proactive use during two-stage revision may improve infection control and reduce downstream utilization. A single-center cohort of 75 adults who underwent two-stage revision for knee PJI (2013-2023) was reviewed. Thirteen patients received a medial gastrocnemius flap and were matched 1:1 to non-flap controls using coarsened exact matching on multidrug-resistant organism status, comorbidity burden, and prior ipsilateral knee surgeries. Outcomes included operative time, length of stay (LOS), infection recurrence, reoperation burden, and 24-month inpatient costs (index, readmission, and reoperation). Flap patients had longer cumulative operative time (12.2 vs. 7.9 h, P=0.006) and LOS (23.0 vs. 17.1 days, P=0.072), with higher index hospitalization costs (median $151,886 vs. $106,531; P=0.081). However, downstream utilization strongly favored flap use: reoperations were significantly less frequent (30.8% vs. 76.9%, P=0.047), and 24-month post-index inpatient costs were markedly lower (median $0 vs. $45,284; P=0.048). Total 2-year inpatient costs remained similar between the groups (median $176,733 vs. $198,040; P=0.758). Infection-free success trended higher in the flap group (92.3% vs. 53.8%, P=0.073), and functional outcomes were largely similar to the matched controls. These findings suggest that integrating medial gastrocnemius flap coverage as part of a planned orthoplastic strategy into the two-stage revision pathway may represent a high-value adjunctive strategy for selected high-risk knees, improving infection control and limiting downstream utilization without increasing the overall 2-year inpatient costs.