JAAOS - 2026-05-07 - Journal Article
Bone Loss Progression in Two-stage Revision Total Knee Arthroplasty: The Potential Role of Reimplantation Timing in Prosthetic Joint Infection Management.
Najafi F, Hahn AK, Sherman M, Stein JM, Parvizi J, Grosso MJ
Topics
Key Takeaway
62.5% of patients undergoing two-stage revision TKA for PJI experienced AORI bone loss progression between stages, with the longest reimplantation interval (mean 147 days) seen in patients progressing from AORI 1 to AORI 3.
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Summary
This study quantified AORI bone loss progression between resection and reimplantation in 160 patients undergoing two-stage revision TKA for PJI from 2007–2022. 62.5% of patients progressed in AORI classification, with 46.9% progressing by two grades; higher baseline AORI score (p<0.001) and longer time to reimplantation (p=0.034) were both independently associated with progression. Infection eradication rates and revision rates did not differ across progression groups, isolating bone loss as the primary consequence of delayed reimplantation.
Key Limitation
Reimplantation timing was not randomized or protocolized, so patients with longer intervals likely had ongoing infection, medical comorbidity, or soft-tissue compromise driving both the delay and the bone loss, making causality between timing and progression impossible to establish.
Original Abstract
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.