Study: Patients Who Go Home After Knee Replacement Do As Well As Those Discharged to Rehab Facility

New York, NY—March 24, 2015

A study by researchers at Hospital for Special Surgery (HSS) finds that patients who go home after knee replacement and receive physical therapy at home do as well as those who go to an in-patient rehabilitation facility.

"There's a common belief that people should go to a rehab facility after joint replacement," said Douglas E. Padgett, MD, the lead investigator and chief of the Adult Reconstruction and Joint Replacement Service at HSS. "Our study found that patients can be safely discharged to their home following knee replacement, dispelling the notion that rehabilitation at an inpatient facility is essential for a successful recovery."

The study, which will be presented the annual meeting of the American College of Orthopaedic Surgeons in Las Vegas on March 24, analyzed data for more than 2,400 patients enrolled in Hospital for Special Surgery's Knee Replacement Registry from 2007 to 2011.  Researchers found no difference in complication rates within six months of knee replacement, whether patients went home or to an inpatient rehab facility after leaving the hospital. Both groups also had similar outcomes in terms of pain and function two years after surgery.

Stephen Lyman, PhD, co-chief investigator and director of the Healthcare Research Institute at HSS, underscores the importance of the study design. He notes that a statistical technique called "propensity score matching" ensured that the research focused on patients with similar characteristics when comparing those who went home versus those who went to inpatient rehab after surgery.

"With propensity score matching, we were able to match patients who had equivalent age, equivalent health conditions and equivalent pre-operative function when comparing their outcomes," Dr. Lyman explained. "So it was a fair comparison between the groups." He noted that this is the largest study on discharge destination to date and the first to validate results with propensity score matching.

"Many patients believe they will do better after knee replacement if they have rehabilitation at an inpatient facility because they will receive more physical therapy," Dr. Padgett notes. "However, in terms of early complications and outcomes at two years, we did not find an advantage."

When patients go home after knee replacement, a physical therapist generally goes to their house three days per week for four to six weeks to help them get back on their feet. Patients who go to a facility receive physical therapy six days per week and often stay for 10 to 14 days. They may then continue to receive PT after they go home, either at home or as an outpatient.

Dr. Padgett notes that the research is timely in light of "value-based" care initiatives introduced by the Centers for Medicare and Medicaid Services (CMS).  "Rehabilitation accounts for much of the health care costs in the first month after knee replacement," he says. "Clearly, it will cost the health care system much less if people can safely go home after surgery."

The vast majority of patients in the study (89 percent) had undergone knee replacement for painful osteoarthritis. The mean age of the patients in this study was 66 years.  Fifty-seven percent of the patients were female and 43 percent were male.

All of the patients completed a questionnaire before surgery to evaluate their pain, stiffness and function, followed by a six-month complication survey and another questionnaire two years after knee replacement to assess their outcomes.

Researchers found no difference in complications after surgery, including manipulation rates for knee stiffness and rate of infection. Two-year outcome scores on pain, function and how much patients improved were also similar. 

Investigators also evaluated how people fared if discharged to a skilled nursing facility versus  an inpatient rehab center after knee replacement.  Within these two groups, the study found no differences in two-year outcome scores.

Despite the study findings, when deciding on discharge destination, Dr. Padgett notes that a patient's social situation often comes into play and needs to be taken into account. "The present study found no difference in complication rate or functional improvements in patients who lived alone compared to patients who lived with others," he said. "However, in many instances, an older adult who lives alone and has no immediate help may require discharge to an inpatient facility based upon social needs."