A review of the Constant score: Modifications and guidelines for its use
Introduction
The requirement to assess surgical results and the means of quantifying them have always provoked intense debate.3 Since Codman's introduction of “the end result idea,” the main aim in assessment has not changed, but our requirements are now more sophisticated and include observation of natural history, follow-up, and disability quantification.
The Constant score was devised by Christopher Constant with the assistance of the late Alan Murley during the years 1981-1986. The score was first presented in a university thesis in 19866 and the methodology published in 1987.5 This functional assessment score was conceived as a system of assessing the overall value, or functional state, of a normal, a diseased, or a treated shoulder. If universally accepted, it would further progress in clinical research in shoulder surgery and enhance the value of multicenter trials.
In this score, 35 points are allocated for subjective assessments of pain and activities of daily living and 65 points are available for objective measures of range of movement and shoulder strength. A young healthy patient can therefore have a maximum score of 100 points.
Section snippets
Pain
Pain is allotted 15 points; the assessment is made on the most severe pain felt by the patient during ordinary activities over a 24-hour period. Thus, many patients will be recording the most severe pain at night. Previously, pain was graded as none, mild, moderate, or severe. This has been replaced by a visual analog scale. It has been proposed that a sliding cursor system with an ungraduated line marked at either end with “no pain” and “intolerable pain,” respectively, be used (Figure 1).
Validation
The Constant score has not been the subject of validation experiments until comparatively recently. In the original paper, this was limited to a study of interobserver error. Conboy et al,4 using a floor-based pulley and positioning as near as possible to 90° of abduction, calculated the interobserver SD as 8.86 and found, based on 95% confidence limits, that a single observer measuring a single subject will be within 17.7 points of the true score. Two- and three-way analyses of variance were
Normal values
The determination of normal values for age and sex is clearly important but will undoubtedly be difficult, as there are noticeable differences between geographically separated populations. It is conceivable that some shoulder centers will be inclined and able to establish their own reference values.
This is extremely important because we are still forced to report results of surgery in absolute terms. All of us know, however, that 110° of flexion and an abduction strength of 1 kg comprise a
Discussion
The limitations of scoring in general must be appreciated before we can embrace a particular method. The problem is to describe a rather complex, multiparametric situation in simple terms (ie, in a numeric figure). Consequently, a scoring system is a conscious simplification, with all the inherent advantages and disadvantages of such an approach. The chosen score's correct and wide use is dependent on its practicality and acceptability. The Constant score has suffered from imprecise terminology
Conclusion
The SECEC Research and Development Committee appreciates the concerns regarding and limitations of the Constant score but believes that we are already in possession of a score that is widely accepted in Europe and increasingly so in other parts of the world and is significantly better than any of the alternatives from the other side of the Atlantic.
This article makes recommendations and modifications, which are the result of considerable discussion and take into account many validation
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