Increased Rate of Complications Following Total Knee Arthroplasty in Patients Who Have Polymyositis.

BACKGROUND: Polymyositis (PM) is a systemic connective tissue disorder that can lead to early onset degenerative joint disease and a need for total knee arthroplasty (TKA). Outcomes of TKA in patients who have PM are not well-documented in the literature. The purpose of this study was to evaluate PM as a risk factor for complications after TKA.

METHODS: Using a national private payer insurance database from 2010 to 2022, PM patients undergoing primary TKA were compared to 10:1 matched controls based on age, sex, and comorbidities. Multivariable logistic regression analyses were done for medical complications up to 90 days and surgical complications up to 2 years. Also, 90-day ED-visit and inpatient readmissions were documented. A total of 25,039 patients undergoing primary TKA were queried, of which 2,290 had PM.

RESULTS: Compared to the matched controls, patients who had PM demonstrated higher rates of medical and surgical complications, including pulmonary embolism (1.0% versus 0.5%, P = 0.001), cerebrovascular accident (1.3% versus 0.7%, P = 0.002), wound complications (3.4% versus 2.1%, P < 0.001) and periprosthetic joint infection at 1 year (1.7% versus 1.3%, P = 0.042) and 2 years (2.6% versus 1.9%, P = 0.006). Patients who had PM displayed elevated 90 day emergency department (14.9% versus 13.3%, P = 0.032) and hospital readmission rate (7.1% versus 4.8%, P < 0.001).

CONCLUSION: Patients who have PM are at higher risks of postoperative medical and surgical complications, including pulmonary embolism, cerebrovascular accident, wound complication, and periprosthetic joint infection. Given these results, it is helpful for orthopaedic surgeons and patients to consider these risks when considering TKA for patients who have PM.