More Pain, More to Gain from New Joints

Joint replacement surgery for more severe osteoarthritis may offer greater benefits

/ Author:  / Reviewed by: Joseph V. Madia, MD

(RxWiki News) With the aging population of baby boomers, the number of joint replacement procedures is rising steadily. But the risks and benefits of surgery might not be the same for every patient.

A recent study found that following total joint replacement, patients with more severe pain, a single affected joint, relatively fewer other health problems and osteoarthritis (OA) had better post-operative outcomes compared with those with less pain, multiple affected joints and inflammatory arthritis.

"Consider the severity of your arthritis before choosing surgery."

The study conducted by Gillian A. Hawker, MD, from the Women's College Hospital and the Institute for Clinical and Evaluative Sciences, Toronto, Ontario, Canada, and colleagues aimed to find predictors of good outcomes after joint replacement surgery, also called total joint arthroplasty (TJA).

The researchers conducted a study of 2,411 patients reporting moderately severe hip and/or knee arthritis. Of this patient population, the researchers were able to obtain and analyze complete scoring data for 202 of these patients (133 knee and 69 hip replacement surgeries).    

The majority of patients, around 80 percent, were female and the mean (average) age of the population was 71 years. More than 90 percent of the participants had osteoarthritis and the remaining had inflammatory arthritis, such as rheumatoid arthritis (RA), based on self-reported physician diagnosis, use of medication and physical examinations. About 83 percent had more than one “troublesome” hip/knee.

Western Ontario McMaster Universities OA Index (WOMAC) score, a widely used standard questionnaire-based score, was calculated for each patient both before and after a primary TJA.

The WOMAC score takes into account pain, stiffness and functional limitations including difficulty with routine tasks such as getting up from chairs and climbing stairs. Higher WOMAC scores indicate higher severity.

A "good outcome" was defined as a WOMAC summary score improvement of at least one minimal important difference (MID), defined by the researchers as half of one statistical unit change in the average, which in this study was 9 points, or more. Basically, a good outcome meant a clinically important improvement in pain and disability.

About 53.5 percent of TJA recipients (51.9 percent of knee replacements and 56.5 percent of hip replacements) reported good outcomes. The average improvement in WOMAC summary score following surgery was 10.2 points. 

According to the study, the best predictive model had four variables, including preoperative WOMAC summary score, number of troublesome hips/knees, type of arthritis and comorbidities.

The study found that the probability of a good outcome was significantly higher for patients with worse pre-TJA WOMAC summary scores. In other words, patients with higher self-reported pain and disability before the surgery were more likely to experience better results than those with relatively lower pain and disability.

Also, participants with osteoarthritis were 33 percent more likely to report positive experiences as compared to those with rheumatoid arthritis. Patient satisfaction with the outcome of TJA was not taken into account.

The results of this study suggest that not all patients experience the same types of benefits after surgery and that there might be a point at which the pain and disability is so high that the pros of surgery outweigh the risks.

For patients with lower pain and disability and for those with rheumatoid arthritis, it might be a better idea to wait before choosing to go the joint replacement route.

Since the study was conducted on a relatively smaller and older population, the researchers conceded that it might be premature to make clinical decisions solely based on the results of this study, and larger studies are called for in this area. But the findings might be a good starting point for patients and clinicians trying to make important decisions about scheduling joint surgery.  

"While demand for joint replacement surgery has increased as our population ages, physicians lack a set of established criteria to help determine what patients will benefit from surgery and at what point during the course of the disease. As physicians, we need to do a better job of targeting treatments to the right patient at the right time by the right provider," said Dr. Hawker.

This study was published in the May issue of Arthritis and Rheumatism.

The study received funding from the Canadian Institutes of Health Research and the Institute for Clinical Evaluative Sciences, which is funded by a grant from the Ontario Ministry of Health and Long-Term Care. The authors disclosed no conflicts of interest or financial affiliations.

Reviewed by: 
Review Date: 
May 15, 2013
Last Updated:
August 12, 2013