FAQs

What is the Constant Score?

The “Constant Score”, CS for short, is a shoulder function measurement tool developed by Christopher Constant while working in his Master of Surgery thesis published in 1986³. Since then, its use has become widely spread and in 1992, the European Society of Shoulder and Elbow surgery recommended its use in publications and communications.

The Constant Score scoring system has four variables which are given a value according to a detailed items grid that adds up to 100.

From a perfect score of 100, it allocates 35 points for self-reported subjective assessment, including the presence of pain and the ability to perform activities of daily living, and 65 points for objective measurement, including 40 points allocated to range of motion and 25 points allocated to strength⁶.

You will find a Constant Score calculator in this website.

What is the Strength Normalized Constant Score (snCS)?

Since its description, some aspects of the CS have been controversial, in particular, the 25 points given to the objective measure of strength, because the strength of the normal shoulder could be different by gender and decrease by age, so the CS would be decreased although could be reflecting a normal function⁴,²,²,⁸,⁷.

The strength component of the CS accounts for 25% of the total score, it is therefore a very significant part of the whole score and the methodology of obtaining and interpreting it is very relevant. Perhaps this would be better explained with an example of everyday practice. Let’s say that we have operated on an 85 years old lady after a four parts fracture of the humeral head, and one year later we obtain a shoulder strength reading of 5. That would probably be a good or very good result, strength wise. Now, let’s say that we obtain the same value one year after the repair of the rotator cuff in a 22 years old construction worker. These same 5 points in the strength section of the CS, wouldn’t count as a very good result at all for him.

The CS without standardization is a useful tool to monitor a particular patient in time but, as the example above shows, it has no meaning comparing two patients results, let alone comparing groups or series of patients

So, we present you with a strength normalized Constant Score (snCS) calculator based on work previously published at the JSES that describes how of shoulder strength decreases with age and how this variation is different for both genders ¹

What is the strength normalized Constant Score (snCS) for?

If you need to monitor progress in a single patient, the “raw” Constant Score might be just fine.

If you want to compare your patient progress with other’s patients, you will need to account for differences in gender or age, otherwise the measurements might mislead you. We advise you to use the snCS

If you want to compare a group of patients Constant Score’s to another, unless you use the snCS, the comparison might be meaningless, because shoulder strength decreases with age and decreases differently for males than for females.

The snCS takes this different age variations into account and allow the comparison to be meaningful

How is shoulder strength measured?

In 2008, a group of experts of the Research and Development Committee of the European Society of Shoulder and Elbow Surgery, published a set of modifications and guidelines regarding the measurement of the Constant Score ⁵.

In particular, regarding strength measurement they released a set of guidelines to which we encourage adherence:

A digital dynamometer is attached distal on the forearm.
A strap is applied to the level of the wrist
Strength is measured with the arm in 90 degrees of elevation in the plane of the scapula (20 degrees in front of the coronal plane) and elbow straight.
Palm of the hand facing the floor (pronation).
The patient is asked to maintain this resisted elevation for 5 seconds.
It is repeated 3 times with at least a minute in between pulls.
The highest reading is noted.
If patient is unable to achieve 90 degrees of elevation in the scapula plane the patient gets 0 points.

References