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If people with a painful limp would just take more exercise, they
will live longer; that is the peverse conclusion of both a cohort study
from Somerset[1] and the accompanying editorial [2]. Most people with a
painful limp would find this suggestion unhelpful.
Neither article makes much of the overwhelming dominance of age as a risk
factor: an effect 20 times more powerful than any other in this study.
Age is a fair but imperfect surrogate for 'miles on the clock' as any car
dealer will confirm. This leads to a simpler alternative conclusion that
does not rely upon a chronic inflammatory or osseovascular conjecture.
Joints usually wear out through overuse. This fatigue failure is
associated with overuse of other structures such as heart valves, arteries
and veins which share the same barely measureable metabolic rates and
minimal ability to heal.
The implications of this more physical explanation are less peverse and
the exact opposite of those proposed, but may ring true to anyone who owns
any mechanical mode of transport, from a pair of shoes upwards: wearing
out of any machinery can be delayed by careful use, or accelerated by
overuse or overloading, or by faulty materials.
If a knee does start to wear out, the timely partial replacement of the
worn out compartment may not prolong the life of a body that is already
wearing out, but it will enhance the quality of it in a highly cost
effective way[3]. Preventing humans from wearing out painfully while
trying to maintain a healthy and fulfilling lifestyle is a much tougher
proposition.
1. Nuesch, E., et al., All cause and disease specific mortality in
patients with knee or hip osteoarthritis: population based cohort study.
BMJ. 342: p. d1165.
2. Cooper, C. and N.K. Arden, Excess mortality in osteoarthritis. BMJ.
342: p. d1407.
3. Willis-Owen, C.A., et al., Unicondylar knee arthroplasty in the UK
National Health Service: an analysis of candidacy, outcome and cost
efficacy. Knee, 2009. 16(6): p. 473-8.
Painful limping and early death
If people with a painful limp would just take more exercise, they
will live longer; that is the peverse conclusion of both a cohort study
from Somerset[1] and the accompanying editorial [2]. Most people with a
painful limp would find this suggestion unhelpful.
Neither article makes much of the overwhelming dominance of age as a risk
factor: an effect 20 times more powerful than any other in this study.
Age is a fair but imperfect surrogate for 'miles on the clock' as any car
dealer will confirm. This leads to a simpler alternative conclusion that
does not rely upon a chronic inflammatory or osseovascular conjecture.
Joints usually wear out through overuse. This fatigue failure is
associated with overuse of other structures such as heart valves, arteries
and veins which share the same barely measureable metabolic rates and
minimal ability to heal.
The implications of this more physical explanation are less peverse and
the exact opposite of those proposed, but may ring true to anyone who owns
any mechanical mode of transport, from a pair of shoes upwards: wearing
out of any machinery can be delayed by careful use, or accelerated by
overuse or overloading, or by faulty materials.
If a knee does start to wear out, the timely partial replacement of the
worn out compartment may not prolong the life of a body that is already
wearing out, but it will enhance the quality of it in a highly cost
effective way[3]. Preventing humans from wearing out painfully while
trying to maintain a healthy and fulfilling lifestyle is a much tougher
proposition.
1. Nuesch, E., et al., All cause and disease specific mortality in
patients with knee or hip osteoarthritis: population based cohort study.
BMJ. 342: p. d1165.
2. Cooper, C. and N.K. Arden, Excess mortality in osteoarthritis. BMJ.
342: p. d1407.
3. Willis-Owen, C.A., et al., Unicondylar knee arthroplasty in the UK
National Health Service: an analysis of candidacy, outcome and cost
efficacy. Knee, 2009. 16(6): p. 473-8.
Competing interests: No competing interests