Bone Loss Progression in Two-stage Revision Total Knee Arthroplasty: The Potential Role of Reimplantation Timing in Prosthetic Joint Infection Management

BACKGROUND: Periprosthetic joint infection (PJI) after total knee arthroplasty (TKA) and its management with two-stage exchange arthroplasty can lead to notable femoral and tibial bone loss, further complicating subsequent reconstruction. This study aims to characterize the extent of bone loss in two-stage TKA revision for infection and assess the effect of reimplantation timing on bone loss progression. METHODS: We conducted a retrospective cohort study of patients who underwent a two-stage TKA revision for PJI between 2007 and 2022. The primary outcome was the degree of bone loss between the index and reimplantation procedures, and whether it was influenced by the rate of timing of reimplantation. Patients undergoing single-stage revisions were excluded. A total of 160 patients met the inclusion criteria. Bone loss was characterized using the Anderson Orthopaedic Research Institute (AORI) classification (1/2A/2B/3) before the index procedure and after reimplantation, with progression defined as an increase in AORI classification. RESULTS: Among the 160 patients, 100 (62.5%) experienced bone loss progression. This included 19 patients (11.9%) with a progression score of 1, 75 patients (46.9%) with a progression score of 2, and six patients (3.75%) with a progression score of 3. A higher AORI score at the index procedure showed a statistically significant association with bone loss progression (P < 0.001). Time to reimplantation was statistically significant (P = 0.034), with patients progressing from AORI 1 to AORI 3 experiencing the longest reimplantation interval (mean: 147 days). No notable differences were observed in revision surgery rates, time to revision surgery, infection eradication rates, or baseline medical comorbidities across progression groups. CONCLUSION: This study demonstrates that two-stage revision TKA for PJI is associated with a notable degree of bone loss, particularly in cases of delayed reimplantation. These findings emphasize the importance of timely reimplantation, or other strategies, to mitigate bone loss and surgical complexity.