Copyright © 2008 by The Journal of Bone and Joint Surgery, Inc.

Commentary & Perspective

Commentary & Perspective on
"Inpatient Compared with Home-Based Rehabilitation Following Primary Unilateral Total Hip or Knee Replacement: A Randomized Controlled Trial"
by Nizar N. Mahomed, MD, ScD, FRCSC, et al.

Commentary & Perspective by
Elizabeth A. Lingard, BPhty, MPhil, MPH*,
Freeman Hospital, Newcastle Upon Tyne, United Kingdom

Posted August 2008

Defining the optimal setting for rehabilitation after the acute perioperative period following hip and knee replacement has been the subject of much discussion. The National Institutes of Health (NIH) found that although rehabilitation was the most widely used practice associated with knee replacement, it was the least studied1. Perioperative management previously has been driven primarily by changes in the reimbursement infrastructure and to a certain extent by surgeon's preferences rather than being guided by evidence-based literature1,2. Mahomed and his colleagues have contributed to the evidence base with this publication, but their paper reveals the complexity of evaluating rehabilitation delivered in different health-care settings and the need for more robust research. Can these authors really justify their recommendation to use home-based rehabilitation based on their results?

Results from their study highlight the enormous variation in the quantity and potentially the quality of rehabilitation offered to patients following total hip and knee arthroplasty. Rehabilitation after joint replacement requires treatment from a multidisciplinary group of health professionals who contribute to different aspects of patient care during this period. This type of health care intervention has more recently been defined as a complex intervention as it requires various interconnecting parts and is affected also by the skill mix of the health professionals and the facilities available3,4. In the paper by Mahomed et al., the input by the physical therapy team was clearly defined in the Appendix but the additional input from other health professionals which would have occurred in the inpatient setting as part of the care pathway is not described. The Community Care Access Centre that provided the home-based care had the potential to provide nursing and home support as well as physical therapy, but in this cohort of patients, the sessions received from the Community Care Access Centre were only physical therapy visits.

The evaluation of complex interventions is difficult because often the complex intervention has not been fully developed and defined prior to the randomized controlled trial being conducted3. Unlike drug trials, where the dose of the drug can be carefully monitored, clinical trials comparing outcomes between two different nonstandardized complex interventions provide limited ability to draw robust conclusions from the data collected. In 2000, the United Kingdom Medical Research Council published a framework for development and evaluation of randomized controlled trials for complex interventions to improve health4. The main recommendation of this document was the need to identify the preliminary work that needs to be undertaken before embarking on the randomized controlled trial. The document recommends the use of an exploratory trial or pilot trial to evaluate if the complex intervention can be delivered in a standardized manner by all contributors to the intervention. Additionally, for studies of rehabilitation after joint replacement, these preliminary studies can establish the acceptable limits of how much the therapist can individualize the intervention, either with respect to the method of delivery or content of the intervention.

In the paper by Mahomed et al., although inpatient rehabilitation patients were managed along established care pathways, there was great variability in the inpatient length of stay, which, on the average, exceeded the fourteen-day target by almost four days. Similarly, the home-based group had great variability in the number of home visits, with vague criteria for discharge, and it is clear that some of these patients went on to receive outpatient physical therapy. The additional health-care costs for continued outpatient care are not included in the economic analysis.

Presentation of the results as means also offers a limited insight into this patient population. It is now well established that hip and knee replacement patients have highly significant improvements in WOMAC and SF-36 physical function and component scores and that the majority of patients are very satisfied with the results of their surgery. What is of more interest is the group of patients who fail to have a good outcome and have persistent pain and functional limitation after surgery and are dissatisfied with the results of surgery. This small group of patients who require ongoing input in terms of consultations, investigations, additional rehabilitation, and potentially additional surgery can incur considerable health-care costs. This group of patients should be included in any study of differences in rehabilitation programs after joint replacement.

Since patient-reported measures such as the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and Short Form-36 have become widely used in studies of hip and knee replacement, there has been a tendency to pool these groups of patients. This trend discounts the fact that these procedures are technically different and result in different postoperative rehabilitation, with knee replacement requiring a much greater input from patients. Although the authors report that they ran the analyses for hip and knee replacement patients in isolation, this would have been on relatively smaller groups and it is therefore unlikely that there was sufficient power to draw the conclusions they report.

This paper highlights the difficulty in studying the efficacy and effectiveness of the rehabilitation process after hip and knee replacement. There is a need to conduct studies that follow the Medical Research Council framework in setting up randomized controlled trials of complex interventions. These trials should study hip and knee replacement patients separately and ideally require a combination of quantitative and qualitative methods. To evaluate the total cost of rehabilitation, such studies need to include not only inpatient and home-based care but also outpatient rehabilitation. Most importantly, future studies need to identify clinical failures and dissatisfied patients, as the rehabilitation program that consistently reports the lowest frequency of these patients has potentially the greatest ability to reduce total health-care costs.

*The author did not receive any outside funding or grants in support of her research for or preparation of this work. Neither she nor a member of her immediate family received payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, division, center, clinical practice, or other charitable or nonprofit organization with which the author, or a member of her immediate family, is affiliated or associated.


1. National Institutes of Health. NIH consensus development conference on total knee replacement. 2003 Dec 8-10. Accessed 2008 Jun 24.
2. Brander V, Stulberg SD: Rehabilitation after hip- and knee-joint replacement: an experience- and evidence-based approach to care. Am J Phys Med Rehabil 2006;85(11 Suppl):S98-S118.
3. Campbell M, Fitzpatrick R, Haines A, Kinmonth AL, Sandercock P, Spiegelhalter D, Tyrer P. Framework for design and evaluation of complex interventions to improve health. BMJ. 2000;321:694-6.
4. Medical Research Council. A framework for development and evaluation of RCTs for complex interventions to improve health. 2000 Apr 1. Accessed 2008 Jun 24.