Identification of biological risk factors for persistent postoperative pain after total knee arthroplasty.

BACKGROUND: There is growing evidence that cytokines and adipokines are associated with osteoarthritis (OA) severity, progression, and severity of associated pain. However, the cytokine response to total knee arthroplasty (TKA) and its association with persistent postoperative pain is not well understood. This study aims to describe the perioperative systemic (plasma) and local (synovial fluid) cytokine profiles of patients who do and do not develop persistent pain after TKA. METHODS: Patients undergoing primary unilateral TKA for end-stage OA were prospectively enrolled. Demographic and clinical data were gathered preoperatively and postoperatively. Synovial fluid was collected pre arthrotomy and plasma was collected at multiple time points before and after surgery. Persistent postoperative pain (PPP) was defined as Numerical Rating Score≥4 at 6 months. Cytokine levels were measured using the V-Plex Human Cytokine 30-Plex Panel (Mesoscale-Rockville, Maryland, USA). Cytokine levels were compared between PPP and minimal pain groups. Given that the study outcomes are exploratory, no adjustment was performed for multiple testing. RESULTS: Incidence of persistent pain at 6 months post TKA was 15/162 (9.3%). Postoperative plasma levels of four cytokines were significantly different in patients who developed persistent postoperative pain: interleukin (IL)-10, IL-1ß, vascular endothelial growth factor, and IL12/IL23p40. Significantly lower IL-10 levels in the prearthrotomy synovial fluid were associated with development of postoperative persistent pain. CONCLUSIONS: This prospective cohort study described a distinct acute perioperative inflammatory response profile in patients who developed persistent post-TKA pain, characterized by significant differences in four cytokines over the first 2 postoperative days. These results support the growing evidence that the patient-specific biologic response to surgery may influence longer-term clinical outcomes after TKA. TRIAL REGISTRATION NUMBER: Clinicaltrials.gov NCT02626533.

Medicaid payer status is associated with increased mortality and morbidity after inpatient shoulder arthroplasty: a multistate analysis, 2007-2014.

BACKGROUND AND OBJECTIVES: Inpatient shoulder arthroplasty is widely performed around the USA at an increasing rate. Medicaid insurance has been identified as a risk factor for inferior surgical outcomes. We sought to identify the impact of being Medicaid-insured on in-hospital mortality, readmission, complications, and length of stay (LOS) in patients who underwent inpatient shoulder arthroplasty. METHODS: We analyzed 89 460 patient discharge records for inpatient total, partial, and reverse shoulder arthroplasties using data from the Healthcare Cost and Utilization Project's State Inpatient Databases for California, Florida, New York, Maryland, and Kentucky from 2007 through 2014. We compared patient demographics, present-on-admission comorbidities, and hospital characteristics by insurance payer. We estimated multilevel mixed-effect multivariate logistic regression models and generalized linear models to assess insurance's effect on in-hospital mortality, readmission, infectious complications, cardiac complications, and LOS; models controlled for patient and hospital characteristics. RESULTS: Medicaid-insured patients had greater odds than patients with private insurance, other insurance, and Medicare of inpatient mortality (OR: 4.61, 95% CI 2.18 to 9.73, p<0.001) and 30-day and 90-day readmissions (OR: 1.94, 95% CI 1.57 to 2.38, p<0.001; OR: 1.65, 95% CI 1.42 to 2.38, p<0.001, respectively). Compared with private insurance, other insurance, and Medicare patients, Medicaid patients had increased likelihood of developing infectious complications and were expected to have longer LOS. CONCLUSIONS: Our study supports our hypothesis that among inpatient shoulder arthroplasty patients, those with Medicaid insurance have worse outcomes than patients with private insurance, other insurance, and Medicare. These results are relatively consistent with previous findings in the literature.