Newswise — WASHINGTON – While more than 900,000 total knee replacement surgeries were performed in the U.S. in 2011 to treat debilitating knee osteoarthritis, the success rate of post-operative functional gains vary widely, according to new research findings presented this week at the American College of Rheumatology Annual Meeting in Washington, D.C.
Knee osteoarthritis is caused by cartilage breakdown in the knee joint. Factors that increase the risk of knee osteoarthritis include obesity, age, prior injury to the knee, extreme stress to the joints, and family history. In 2005, 27 million Americans suffered from osteoarthritis, and one in two people will have symptomatic knee arthritis by age 85.
Starting in 2008, researchers at Arcadia University and the University of Massachusetts Medical School reached out to 179 people with knee OA patients who were undergoing total knee replacement surgery, 68 percent of these people were female – with a mean age of 65.1. All the participants wore an accelerometer ankle device to measure walking before surgery, with a mean use of 3.3 days worn. The accelerometer was worn by 174, 163 and 168 participants at least one valid day at baseline, eight weeks and six months after surgery. In addition to patient self-reports and accelerometer information on those patients, the researchers requested and examined physical therapy records of 90 individuals who completed outpatient rehabilitation and 27 who completed their rehabilitation in home-care.
The goal was to analyze how physical therapy might be related to levels of post-operative walking function, says Carol Oatis, PhD, PT, lead investigator in the study and a professor of physical therapy at Arcadia University.
“Our findings demonstrated wide variability in the utilization of physical therapy in these subjects, in the amount of physical therapy, the number of days in physical therapy, and also, wide variability in the kind of physical therapy after surgery,” says Oatis.
Examination of the accelerometer data showed that participants’ average and median daily step counts were approximately 1,000 steps fewer at eight weeks after surgery than they were prior to surgery. At six months after surgery, the mean and median increase in steps from pre-operative levels was only 738 and 354 steps, respectively. However, 30 percent of the participants ended physical therapy after eight weeks and were left to continue their rehabilitation alone, says Oatis. Approximately 40 percent completed their rehabilitation after nine weeks.
“What struck me was that a large percentage of people had been discharged from physical therapy while their physical activity level was still greatly below their preoperative levels,” she says. “I thought that was a pretty stunning picture of the relationship between the timing of rehabilitation services and functional activity.”
It is unclear what communication or direction physical therapists are giving to patients after total knee replacement, and there is no standardization of postoperative rehabilitation, Oatis notes. “We don’t know what physical therapists are saying to patients about what they need to work on after the rehabilitation ends. Many patients have a higher expectation of functional ability following surgery than they actually attain. By recognizing the disconnect, we can be more overt in conversations with patients, and help them focus on physical activity and behavioral goals after surgery.”
Funding for this study was provided in part by the National Institute of Arthritis and Musculoskeletal and Skin Diseases.
The American College of Rheumatology is an international professional medical society that represents more than 9,000 rheumatologists and rheumatology health professionals around the world. Its mission is to advance rheumatology. The ACR/ARHP Annual Meeting is the premier meeting in rheumatology. For more information about the meeting, visit www.acrannualmeeting.org or join the conversation on Twitter by using the official hashtag: #ACR2012.
Learn more about living well with rheumatic disease as well as rheumatologists and the role they play in health care. Also, discover the ACR’s Simple Tasks campaign, which highlights the severity of rheumatic diseases and the importance of early and appropriate referral to a rheumatologist.
Editor’s Notes: Carol Oatis, PhD, PT will present this research during the ACR Annual Meeting at the Walter E. Washington Convention Center at 9:00-11:00 AM on Monday, November 12 in the Poster Hall (Hall B). Dr. Oatis will be available for media questions and briefing at 1:30 PM on Tuesday, November 13 in the on-site press conference room, Room 203 A-B.
Presentation Number: 1585
Physical Activity and Timing of Discharge From Physical Therapy Following Total Knee Replacement
Carol A. Oatis (Arcadia University, Glendale, Pa.)
Wenjun Li (University of Massachusetts Medical School, Worcester, Mass.)
Milagros Rosal (University of Massachusetts Medical School, Worcester, Mass.)
David Ayers (University of Massachusetts Medical School, Worcester, Mass.)
Patricia D. Franklin (University of Massachusetts Medical School, Worcester, Mass.)
Background/Purpose: In 2009 over 620,000 total knee replacement (TKR) surgeries were performed. That number is expected to increase to 3.5 million annually by 2030. Post-operative functional gain is variable. On average physical activity and functional ability remain diminished one year post TKR when compared to age matched controls. The purpose of this study was to examine the recovery pattern of physical activity from TKR to 6 months post-surgery and its relation to the timing of physical therapy (PT) service received.
Methods: Subjects were 179 participants in an NIH funded RCT of telephone support interventions following unilateral, primary TKR. We requested the PT records from the first 102 participants who completed their TKR rehabilitation in outpatient PT and the first 40 participants who completed their PT rehabilitation in homecare and used no outpatient PT services. We received 90 outpatient and 27 homecare PT records. Participants were asked to wear an accelerometer (Step Activity Monitor™) at the ankle for four consecutive days (2 weekday and 2 weekend) before surgery and at 8 weeks and 6 months after surgery. Valid wear days required a minimum of 10 hours of wear time. Time from surgery to discharge from PT was extracted from PT records.
Results: Participants included 68% female, with a mean (SD) age of 65.1 (8.61). Mean (SD) age was 64 (8.4) and 66 (7.7) years for those completing rehabilitation in outpatient and home care respectively. All participants wore the accelerometer preoperatively with a mean of 3.3 days worn. 174, 163 and 168 participants had at least one valid wear day at baseline, 8 weeks and 6 months after surgery respectively. Mean (SD) steps/day were 7472 (3156), 6658 (3074) and 8295 (3531) at baseline, 8 weeks and 6 months respectively (Figure). Average and median (5970) daily step counts at 8 weeks were approximately 1000 steps fewer than preoperative levels. Mean (SD) and median change in daily steps at 6 months were 738 (2591) and 354 respectively. 30% of participants had completed their rehabilitation by 8 weeks post-surgery and 40% had completed it by 9 weeks. All but one participant who completed rehabilitation in home care had completed it by 8 weeks.
Conclusion: Although average physical activity at 8 weeks post TKR as measured by daily step counts was lower than pre-operative levels, almost one-third of patients had stopped receiving post TKR rehabilitation by that time. Increased functional ability and physical activity are frequent goals of TKR surgery. Our data show that many patients discontinue post TKR rehabilitation when their physical activity is still below pre-operative levels. Further research is needed to understand the association between recovery of physical activity and the timing of PT services post TKR.
Disclosure: C. A. Oatis, None; W. Li, None; M. Rosal, None; D. Ayers, None; P. D. Franklin, Zimmer, Inc.