Normalization of the Constant score in the Spanish population.

Background: Normal Constant score values for healthy shoulders can vary between regions and change over the years as life expectancy increases and physical condition improves. Spain's population is one of the healthiest and has one of the highest life expectancies in the world, which could be reflected in its normal Constant score values. The purpose of this study is finding the normal Constant score values in the Spanish population.

Methods: Cross-sectional study completed between 2023-2024, including subjects older than 18 years of age without any previous or ongoing shoulder condition. Constant score was taken for both shoulders of every subject. A stratified analysis of total and subtotal scores was performed, grouping subjects by age and sex.

Results: A total of 505 subjects and 1010 shoulders were included, with a mean age of 52.3 ± 18.6 years and men/women ratio of 39.6%/60.4%. Five groups were formed according to age: 18-30 years-old (18.4%), 31-45 years-old (16.4%), 46-60 years-old (29.8%), 61-75 years-old (23.7%), and over 75 years-old (11.7%). Each of these groups were divided in two groups according to sex, making a total of 10 groups. Mean Constant score was 88.9 ± 10.9, the group of men between 18-30 years-old having the highest mean score (99.2 ± 3.0) and the group of women over 75 years-old having the lowest mean score (75.3 ± 8.8). A statistically significant inverse correlation was found between total score and age (r = -.47, p < .001). Total score was also significantly lower in the women (84.5 ± 8.2 vs 92.6 ± 8.5, p < .001). The decrease in mobility (r = -.45, p < .001) and strength (r = -.40, p < .001), and the difference in strength between the men and the women (10.6 ± 3.8 vs 6.0 ± 2.0, p < .001) were the main underlying causes of the difference in total Constant score between groups.

Conclusion: Normal values of the Spanish version of the Constant score in healthy shoulders of the Spanish population decrease with age and are lower in women, the main differences being found in shoulder mobility and strength. Global scores found in this population are higher than those previously published for English, American, and Swiss populations.