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Pain in the knee

Survey
Results
Comment

Most people working in primary care are aware that knee pain is common, especially in older people. Much is mild, and has little impact on how those with knee pain get on with their lives. But, as with most conditions, there is a gradation in severity, so that some have more pain, or are disabled, some should be getting specialist advice, and some of those perhaps need a joint replacement. Knowing the numbers would be helpful in planning services, and a Manchester study [1] provides them.

Survey

The survey was conducted in an urban part of Manchester. Populations were divided into eight groups defined by age and sex, and about 250 people in each group sampled in each medical practice, with 5,600 questionnaires sent initially. This first phase questionnaire asked about musculoskeletal symptoms, pain in various sites for more than one week in the past month, demographics, and employment status. This questionnaire also included a health assessment questionnaire to help define disability.

A second questionnaire was sent to those reporting knee pain (not multiple pain). This asked about severity, chronicity, and primary care and hospital consultations for knee pain. A sample of responders was invited for examination.

Results

Response rates at all levels of the study were generally good, at about 80% or above. Overall prevalence of knee pain was similar in adult men and women at about 19%, but was higher than this in older persons (Figure 1 for women and Figure 2 for men). Knee pain plus disability defined as a health assessment questionnaire score of 0.5 or above was lower (Figures 1 and 2), at about 6% overall. Knee pain plus disability defined as work disability in those aged below 65 years was 2.8%.



Figure 1: Knee pain reported by women, all reported pain, and pain plus disability







Figure 2: Knee pain reported by men, all reported pain, and pain plus disability





Responses to the second questionnaire were similar between women and men, and showed the same gradation with age. Overall, 12% of adults had knee pain that was moderate or severe, 9% had knee pain of more than five years, and 3.4% had moderate or severe pain and disability.

Predictors of knee pain were sought. Factors associated with increased knee pain were higher BMI (Figure 3), increasing social deprivation (Figure 4), and South Asian ethnicity. A significant proportion of knee pain could be ascribed to being overweight or obese. Of all knee pain, this was 21%, and up to 37% for moderate or severe pain with disability. Most of this came from being overweight (BMI 25-30), not being obese.



Figure 3: Adjusted odds ratio for knee pain and BMI







Figure 4: Adjusted odds ratio for knee pain and Townsend deprivation index





From an analysis of 66 patients seen by a consultant rheumatologist it was estimated that 4.5% of the adult population needed specialist treatment, most (2.8%) for orthopaedics. The unmet need was about twice the level of need currently being met. In a practice population of 10,000 adults, this unmet need amounts to 320 patients.

Comment

When planning services, it always helps if you have some idea of what you need to provide. A simple sentence this, but one for which it is often desperately difficult to provide numbers. For knee pain in the community, we have some numbers to help.

Bandolier 103 reported a survey showing a large unmet need for hip replacements, and the present survey shows another large unmet need for knee pain, probably including replacement. But it also demonstrates that there is an opportunity to reduce the burden of knee pain, by showing the link with being overweight. Reducing excess weight in the community will have many paybacks, not just heart disease and cancer, but also in a reduced requirement for specialist services for musculoskeletal conditions.

Reference:

  1. R Webb et al. Opportunities for prevention of clinically significant knee pain: results from a population-based cross sectional survey. Journal of Public Health 2004 26: 277-284.

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