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Failure Rates After Treatment of Periprosthetic Joint Infection Using Musculoskeletal Infection Society Outcome
John R Tyler1, Whisper Grayson1, Amy Wozniak2
1Department of Orthopaedic Surgery & Rehabilitation, Loyola University Medical Center, Maywood, Illinois.
Background:
Reported success rates after treatment of periprosthetic joint infection (PJI) vary widely, in part because treatment failure is not defined uniformly. Modern consensus outcome frameworks such as the Musculoskeletal Infection Society Outcome Reporting Tool (MSIS ORT) and Delphi criteria may not fully capture clinically meaningful outcomes. This study compared failure rates after treatment of PJI using MSIS-ORT, Delphi, and a pragmatic clinical definition; assessed agreement between these definitions at the patient level; and examined the criteria responsible for discordant classifications.
Methods:
A retrospective cohort study was performed of 198 unique hip and knee PJI episodes treated at a single academic medical center from 2007 to 2024. The primary analytic cohort consisted of 184 episodes with either a documented failure event before 12 months or documented follow-up of at least 12 months. Failure rates were calculated using MsSIS-ORT, Delphi, and pragmatic clinical definitions. Agreement between definitions was assessed using cross-tabulations, and discordant cases were reviewed to identify the criteria responsible for disagreement.
Results:
In the 184-episode primary analytic cohort, failure rates were 43.5% (80 of 184) by MSIS-ORT, 40.8% (75 of 184) by Delphi, and 47.3% (87 of 184) by the clinical definition. Among debridement, antibiotics, and implant retention procedures, failure rates were 44.8, 42.4, and 52.0%, respectively; among staged revisions, failure rates were 40.7, 37.3, and 37.3%, respectively. The MSIS ORT and Delphi showed high concordance, but 13 of 104 episodes (12.5%) classified as successful by MSIS-ORT were considered failures under the clinical definition.
Conclusions:
Failure after treatment of PJI remained common regardless of the outcome framework applied. Although MSIS ORT and Delphi produced similar aggregate estimates, these frameworks were not fully interchangeable with a pragmatic clinical definition at the patient level. Definitional choice materially influences interpretation of PJI treatment outcomes.
Insights
Treatment failure after periprosthetic joint infection (PJI) is common. Standard outcome tools like MSIS ORT and Delphi differ from clinical definitions, impacting PJI treatment success interpretation.
Area of Science:
- Orthopedic Surgery
- Infectious Diseases
- Biostatistics
Background:
- Periprosthetic joint infection (PJI) treatment success rates vary due to inconsistent failure definitions.
- Existing consensus frameworks like MSIS ORT and Delphi may not fully reflect clinically meaningful outcomes.
- This study evaluates PJI treatment failure rates using multiple definitions.
Purpose of the Study:
- Compare failure rates of PJI treatment using MSIS ORT, Delphi criteria, and a pragmatic clinical definition.
- Assess agreement between these definitions at the patient level.
- Identify criteria causing disagreements between PJI outcome classifications.
Main Methods:
- Retrospective cohort study of 184 hip and knee PJI episodes (2007-2024).
- Calculated failure rates using MSIS ORT, Delphi criteria, and a clinical definition.
- Assessed inter-definition agreement and reviewed discordant cases.
Main Results:
- Overall PJI treatment failure rates were 43.5% (MSIS ORT), 40.8% (Delphi), and 47.3% (clinical definition).
- Failure rates varied between debridement, antibiotics, and implant retention (DAIR) and staged revision procedures.
- 12.5% of cases deemed successful by MSIS ORT were classified as failures by the clinical definition.
Conclusions:
- PJI treatment failure remains high irrespective of the outcome framework used.
- MSIS ORT and Delphi criteria show high concordance but are not interchangeable with clinical definitions.
- The choice of definition significantly impacts the interpretation of PJI treatment outcomes.
