Timing and Factors Associated with Revision for Infection after Primary Total Knee Arthroplasty Based on American Joint Replacement Registry Data

BACKGROUND

Infection following total knee arthroplasty (TKA) remains a challenging clinical problem. Using American Joint Replacement Registry (AJRR) data, this study examined factors related to the incidence and timing of infection.

METHODS

Primary TKAs performed from January 2012 through December 2018 among patients ≥65 years of age at surgery were queried from AJRR and merged with Medicare data to enhance capture of revisions for infection. Multivariate Cox regressions incorporating patient, surgical, and institutional factors were used to produce hazard ratios (HR) associated with revision for infection and mortality after revision for infection.

RESULTS

Among 525,887 TKAs, 2,821 (0.54%) were revised for infection. Men had an increased risk of revision for infection at all time intervals (≤90 days, HR=2.06, 95% confidence interval (CI): 1.75-2.43, P<0.0001; >90 days to 1 year, HR=1.90, 95% CI: 1.58-2.28, P<0.0001; >1 year, HR=1.57, 95% CI: 1.37-1.79, P<0.0001). TKAs performed for osteoarthritis had an increased risk of revision for infection at ≤90 days (HR=2.01, 95% CI: 1.45-2.78, P<0.0001), but not at later times. Mortality was more likely among patients who had a Charlson Comorbidity Index (CCI)≥5 compared to those who had a CCI≤2 (HR=3.21, 95% CI: 1.35-7.63, P=0.008). Mortality was also more likely among older patients (HR=1.61 for each decade, 95% CI: 1.04-2.49, P=0.03).

CONCLUSION

Based on primary TKAs performed in the United States, men were found to have a persistently higher risk of revision for infection, while a diagnosis of osteoarthritis was associated with a significantly higher risk only during the first 90 days after surgery.

Migration Patterns for Revision Total Hip Arthroplasty in the United States as Reported in the American Joint Replacement Registry

BACKGROUND

Revision total hip arthroplasty (revTHA) is associated with higher rates of complications and greater costs than primary procedures. The aim of this study is to evaluate the effect of hospital size, teaching status, and indication for revTHA, on migration patterns in patients older than 65 years old.

METHODS

All THAs and revTHAs reported to the American Joint Replacement Registry from 2012 to 2018 were included and merged with the Centers for Medicare and Medicaid Services database. Migration rate was defined as a patient's THA and revTHA procedures that were performed at separate institutions by different surgeons. Migratory patterns were recorded based on hospital size, teaching status, and indication for revTHA. Analyses were performed by statisticians.

RESULTS

The number of linked procedures included was 11,906. Migration rates in revTHA due to infection were higher for small hospitals than large hospitals (46.6% vs 28.6%, P < .0001). Migration rates were higher comparing non-teaching with teaching hospitals (55% vs 34%, P < .0001). This difference was significant for periprosthetic fractures (70.6% vs 37.2%, P = .005), instability (56.5% vs 35.5%, P = .04), and mechanical complications (88.9% vs 34.7%, P < .05). Most patients migrated to medium or large hospitals rather than small hospitals (89% vs 11%, P < .0001) and to teaching rather than non-teaching institutions (82% vs 18%, P < .0001).

CONCLUSION

Hospital size and teaching status significantly affected migration patterns for revTHA. Migration rates were significantly higher in small non-teaching hospitals in revTHA due to infection, periprosthetic fracture, instability, and mechanical complications. Over 80% of patients migrated to larger teaching hospitals.