RESEARCH - Relationship between weakness and muscle wasting in RA

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ls of the Rheumatic Diseases, 1994, Vol 53, 726-728

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PAPERS

Relationship between weakness and muscle wasting in rheumatoid arthritis

PS Helliwell and S

Rheumatology and Rehabilitation Research Unit, Leeds, United Kingdom.

OBJECTIVE--To relate weakness of grip to loss of forearm muscle bulk, hand

joint deformity, and hand joint tenderness in patients with rheumatoid

arthritis (RA). METHODS--Using anthropometric data we have estimated the

anatomical cross-sectional area (CSA) of forearm muscles in 100 subjects

with RA compared with 100 aged and sex-matched normal subjects. We also

recorded hand joint tenderness using a modification of the Ritchie articular

index, and a simple index of hand joint deformity. RESULTS--We found a

significant reduction in anatomical CSA in RA (forearm CSA in normal

subjects 29.7 cm2 and in RA 25.9 cm2; p = 0.002). In simple linear

regression we found that 46.3% of the variation in grip strength in normal

subjects was explained by variation in muscle CSA; in RA this figure

decreased to 33.4%. Adding terms for joint deformity and pain in a multiple

regression model improved the amount of variation explained to 37.9%.

CONCLUSIONS-- Although there is significant muscle wasting in RA, it is

likely that reduction in strength is also attributable to joint deformity

and pain leading to inhibition of grip directly and, indirectly, by

arthrogenous muscle inhibition. Doubts remain about the quality of muscle in

RA.

http://ard.bmjjournals.com/cgi/content/abstract/53/11/726

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