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How good is a joint replacement?

Study
Results
Comment

Patient perspectives of osteoarthritis are not always captured by clinical trials, which use outcomes like WOMAC scales, or pain in the rather contrived setting of walking on a flat surface. Though these are important outcomes, and necessary for proving clinical efficacy, they do not always help patient or professional understand the full benefit of a treatment. With surgery it may be more difficult to understand the benefits, especially when the aim is to cure as much as ameliorate symptoms.

Understanding the patient perspective, and the underlying problems with arthritis should come first. A UK survey of 3,127 patients whose diagnosis of osteoarthritis had been confirmed by a GP, contained results on 18 quality of life indicators [1]. Figure 1 shows that sleeping, walking, and such everyday activities as bathing and dressing affected people often. It is little wonder that in chronic diseases, the largest negative impact on quality of life is seen in musculoskeletal disorders of osteoarthritis, rheumatoid arthritis, and back pain (Bandolier 83).


Figure 1: Everyday tasks causing problems for patients with OA



A North Yorkshire survey suggested that over and above those already having a joint replacement, about 380/100,000 persons aged 55 and over might benefit from hip replacement, with as few as 45/100,000 actually on a waiting list (Bandolier 103). If quality of life is low with arthritis, what happens to quality of life after joint replacement?

Study

An Australian study [2] reported on part of an ongoing prospective trial that included patients of nine orthopaedic surgeons in four Sydney hospitals. Patients with a diagnosis of osteoarthritis or rheumatoid arthritis were eligible, though here only results for osteoarthritis were reported.

Preoperatively, and every three months after joint-replacement operation for 12 months, patients were mailed monthly self-administered WOMAC and SF-36 questionnaires, and reminded to complete them by telephone. WOMAC is the Western Ontario and McMaster Universities Osteoarthritis index, measuring dimensions of pain, stiffness and physical function. SF-36 is a generic quality of life questionnaire assessing 36 items in eight domains. WOMAC scoring is on a 1-5 scale, which was transformed to a 0-100 scale, and SF-36 scores on a 0-100 scale.

Results

There was a 67% response rate in 252 patients recruited. The 194 participants had an average age of 74 years, and 86 had osteoarthritis of the hip and 108 of the knee. The overall follow up averaged 11 months. Disease duration averaged 10 years, and half were women.

There were significant improvements for all three areas of the WOMAC scale of physical function (Figure 2), where lower scores are better), pain, and stiffness for both hip and knee replacement. For physical functioning (Figure 2), hip replacement resulted in a beneficial reduction in the WOMAC score from 37 to 12.


Figure 2: Physical functioning (WOMAC). Higher scores are worse.



There were significant improvements in the SF-36 quality of life questionnaire for most of the eight domains for both hip and knee replacement (Table 1, where higher scores are better). Bodily pain, physical functioning and physical role functioning were most improved. Exceptions were emotional role function for both hip and knee, and general health and mental health for knee replacements, though both scores were high initially.


Table 1: Preoperative and 12 month scores in SF-36 domains (0-100) for hip and knee replacement


Hip replacement
Knee replacement
SF-36 domain
Preop
12 months
Preop
12 months
General health
66
74
71
70
Bodily pain
33
73
33
57
Physical function
27
67
25
50
Physical role function
15
59
18
50
Social function
53
89
59
77
Mental health
71
82
70
77
Emotional role function
60
72
54
65
Vitality
47
68
47
59
Bold, shaded areas show statistical significance at 5% level. Higher scores indicate a better health state.

For both of the scales the first three months following joint replacement found the largest changes. Improvements tended to continue over the succeeding nine months, but at a lower rate.

Comment

These are major beneficial changes from joint replacement surgery. A previous report [3] demonstrated that at all ages from 55 years, hip replacement brought SF-36 scores for osteoarthritis patients back to population norms for age. Knee replacement was almost as good, except that in the age group of 55-64 years population norms were not all achieved.

For most patients having hip or knee replacement large quality of life gains will occur. With the modest cost of the operations, this will mean the cost per quality-adjusted life year will be low. These results also underscore the quality of life losses by people with osteoarthritis who have not had a joint replacement. Large gains in quality of life after joint replacement means that quality of life must have been pretty low with osteoarthritis. This ties together the information we have rather neatly.

References:

  1. B Crichton, M Green. GP and patient perspectives on treatment with non-steroidal anti-inflammatory drugs for the treatment of pain in osteoarthritis. Current Medical Research & Opinion 2002 18: 92-96.
  2. CJ Bachmeier et al. A comparison of outcomes in osteoarthritis patients undergoing total hip and knee replacement surgery. Osteoarthritis and Cartilage 2001 9: 137-146.
  3. LM March et al. Outcomes after hip or knee replacement surgery for osteoarthritis. Medical Journal of Australia 1999 171: 235-238.

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