Constant, J Shoulder Elbow Surg 2008 - A Review of the Constant Score: Modifications and Guidelines for Its Use - Article Summary

A Review of the Constant Score: Modifications and Guidelines for Its Use

Constant, Boileau, et al.·J Shoulder Elbow Surg·2008·805 citations·Review article

This 2008 SECEC committee paper standardizes the methodology of the Constant-Murley shoulder score. It clarifies how each domain is measured, condemns manual muscle testing, and issues formal guidelines for consistent use across centers. It also introduces the relative Constant score as the recommended reporting standard.

Key Findings

The Constant-Murley score totals 100 points, split as 35 subjective (15 pain + 20 ADL) and 65 objective (40 ROM + 25 strength). The objective component dominates — a patient who cannot lift their arm loses more than half the score before subjective complaints are even counted.
Interobserver variability is clinically significant: a single observer measuring a single patient may fall within ±17.7 points of the true score (SD 8.86, 95% CI), and observers differed significantly in total scores (F = 4.22, P = .02). When comparing Constant scores across centers or over time, a difference smaller than ~18 points may reflect measurement error rather than a real clinical change.
Manual muscle testing is explicitly condemned as an acceptable strength method. The only two approved techniques are the Isobex isometric dynamometer and a fixed spring balance, both measured at 90° abduction in the scapular plane with the forearm pronated. Maximum of 3 reps, each separated by at least 1 minute, with the highest value recorded.
The Isobex and fixed spring balance are clinically interchangeable in pathologic shoulders (P < .76, no significant difference in 20 patients). In 50 healthy volunteers the difference was only 1-2 points, despite statistical significance (P < .001). This means the cheaper spring balance is an acceptable substitute in most clinical settings.
All ROM measurements must be active and pain-free. If a patient reaches 140° with pain but only 110° without, the score records 110°. Patients unable to reach 90° abduction for the strength test receive a strength score of 0.
Normal values come from 900 healthy individuals across age and sex groups. Scores decline substantially with age and diverge by sex in middle decades (e.g., males 21-30: mean 98 vs. females 71-80: mean 69). The relative Constant score, raw score divided by the age- and sex-matched norm, is the recommended reporting standard, because the same absolute score means something very different in a 25-year-old versus an 80-year-old.
Comparison with the contralateral shoulder is explicitly discouraged as a normative reference, because too many patients in a given population have bilateral shoulder pathology that would artificially lower the reference value.

Board PearlThe Constant score allocates 65 of 100 points to objective measures; always use age- and sex-matched norms, never manual muscle testing.

Reference

A Review of the Constant Score: Modifications and Guidelines for Its Use.

Constant, Boileau, et al.J Shoulder Elbow Surg2008805 citationsReview article