Summary

Understanding factors involved in discharge outcomes after UKA places important focus, among others, on modifiable risk factors such as medical management, smoking, and prevention of weight loss in optimizing outcomes.

Abstract

Background

As unicompartmental arthroplasty (UKA) is becoming an increasingly utilized treatment option for knee osteoarthritis, disposition planning remains a critical component of postoperative care and rehabilitation. This study sought to (1) investigate differences in outcomes in patients undergoing UKA subsequently discharged to home, skilled nursing facilities (SNF), and inpatient rehabilitation facilities (IRF); and (2) identify predictors of major adverse events (AEs), reoperation, and nonhome disposition.

Methods

The American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database was queried for all patients undergoing UKA from 2011-2018. Bivariate analyses were performed to compare demographics, comorbidities, perioperative variables, and 30-day AEs. Multivariable logistic regressions were conducted to identify patient characteristics associated with nonhome disposition, IRF as opposed to SNF disposition, postdischarge major AEs, and readmission and reoperation within 30 days of surgery.

Results

10,243 patients underwent UKA between 2011-2018 who were discharged to home, SNF, or IRF. Compared to home and SNF discharge, disposition to an IRF demonstrated a tripled (IRF: 3.8% vs. Home: 1.3%, P=0.001) and quadrupled (IRF: 3.8% vs. SNF: 1.0%, P=0.011) rate of minor AEs, respectively. While patients sent to a nonhome facility had higher overall rates of major AEs (IRF: 2.7% vs. SNF: 2.3% vs. Home: 1.6%), these differences were not statistically significant (P>0.05). Overall rates of unplanned readmission (Nonhome: 1.7% vs. Home: 1.6%, P=1.00) and reoperation (Nonhome: 1.3% vs. Home: 0.9%, P=0.267) did not significantly vary between nonhome and home disposition. Factors significantly associated with nonhome discharge were increasing age (OR: 1.50), female sex (OR: 1.84), American Society of Anesthesiologists (ASA) class >2 (OR: 2.04), >10% loss of body weight preoperatively (OR: 4.42), dependent functional status (OR: 1.82), longer hospital stay (OR: 2.17 per 1-day increase), and intra-/post-operative myocardial infarction (OR: 4.56). Predictors of enduring a major AE post discharge include male sex (OR: 1.51), dependent functional status (OR: 2.24), and current smoking status (OR: 2.04). Requiring an unplanned reoperation after UKA was associated with smoking (OR: 2.52), dependent functional status (OR: 2.35), longer operating times (OR: 1.0045), and enduring a predischarge minor AE (OR: 9.57).

Conclusion

Overall rates of major AEs did not significantly differ by discharge destination, but patients sent to nonhome facilities were more likely to endure a myocardial infarction or develop a venous thromboembolism. The risk of nonhome discharge may be reduced by optimizing medical comorbidities, preventing >10% weight loss preoperatively, and minimizing long hospital stays. Smoking cessation, better control of medical comorbidities, and judicious wound, genitourinary, and pulmonary care may help reduce the occurrence of postoperative major AEs, readmissions, and reoperations. Nonhome disposition was not significantly associated with having a major AE post discharge, readmission, or reoperation within 30 days of UKA.