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
- Balcells-Diaz E, Daunis IE. Shoulder strength value differences between genders and age groups. J.Shoulder.Elbow.Surg. 2017 des 18;(1058-2746 (Linking)).
- Blonna D, Scelsi M, Marini E, Bellato E, Tellini A, Rossi R, et al. Can we improve the reliability of the Constant-Murley score? J.Shoulder.Elbow.Surg. 2012 gen;21(1058-2746 (Linking)):4-12.
- Constant CR. Age Related Recovery of Shoulder Function After Injury. 1986;
- Constant CR. An evaluation of the Constant-Murley shoulder assessment. J.Bone Jt. Surg.Br. 1997 jul;79(0301-620X (Linking)):695-696.
- Constant CR, Gerber C, Emery RJ, Sojbjerg JO, Gohlke F, Boileau P. A review of the Constant score: modifications and guidelines for its use.[see comment]. J. Shoulder.& Elbow.Surgery.17(2)355.-61.,. 2008 març;Apr.
- Constant CR, Murley AH. A clinical method of functional assessment of the shoulder. Clin. Related.Research.(214.)160.-4,. 1987 gen;
- Katolik LI, Romeo AA, Cole BJ, Verma NN, Hayden JK, Bach BR. Normalization of the Constant score. J.Shoulder.Elbow.Surg. 2005 maig;14(1058-2746 (Linking)):279-285.
- Kristensen MT, Aagesen M, Hjerrild S, Lund Skov LP, Hovmand B, Ban I. Reliability and agreement between 2 strength devices used in the newly modified and standardized Constant score. J.Shoulder.Elbow.Surg. 2014 des;23(1058-2746 (Linking)):1806-1812.