A comparison of methods for shoulder strength assessment and analysis of Constant score change in patients aged over fifty years in the United Kingdom

Normal values for shoulder assessment are imperative for the diagnosis of pathology and measurement of treatment outcome. Normal values for the United Kingdom are currently not known. This study comprised 108 control patients aged over 50 years who were under the care of one general practitioner, and the Constant score was measured. The Constant score was assessed via 3 techniques for strength measurement: maximum strength with myometer, mean strength with myometer, and maximum strength with fixed spring balance. Myometer maximum strength values were very similar to fixed spring balance maximum strength values, with a mean difference of 0.5. Myometer mean strength was lower than myometer maximum strength by 3 points. Age and sex both significantly affected Constant score (P < .001 for both). The Constant score fell by 0.3 points per year over 50 years of age. Men had a score that was 7.5 points greater than that in women. The Constant score decreases predictably with age in the United Kingdom. Methods of strength assessment are not the same. A uniform method of shoulder strength assessment is required to allow for meaningful comparisons between series.