This twin study asked how much of rotator cuff degeneration is inherited versus environmental. Using MRI-based Sugaya grading in 33 elderly monozygotic and dizygotic twin pairs, the authors calculated heritability by comparing correlation between the two twin types. The goal was to separate genetic from shared and unique environmental contributions.
Family history of rotator cuff tears is real but should not be treated as destiny. This study puts a number on it: genetics explains roughly 18% of degeneration, while environment explains more than 80%.
That matters when you counsel a patient whose sibling had a cuff tear. The modifiable factors, occupation, smoking, metabolic disease, BMI, deserve the emphasis because they carry most of the weight. The job-type correlation is the practical anchor. Heavier manual work tracked with worse Sugaya grades even in identical twins, meaning load, not just biology, drives tendon breakdown.
Keep the caveats in mind. This is a small cross-sectional twin sample of 33 pairs, too few for full quantitative genetic modeling, so the 18% figure is an estimate rather than a fixed truth. It also complements, not contradicts, the gene-association literature confirming cuff disease is polygenic.
This twin study asked how much of rotator cuff degeneration is inherited versus environmental. Using MRI-based Sugaya grading in 33 elderly monozygotic and dizygotic twin pairs, the authors calculated heritability by comparing correlation between the two twin types. The goal was to separate genetic from shared and unique environmental contributions.
Family history of rotator cuff tears is real but should not be treated as destiny. This study puts a number on it: genetics explains roughly 18% of degeneration, while environment explains more than 80%.
That matters when you counsel a patient whose sibling had a cuff tear. The modifiable factors, occupation, smoking, metabolic disease, BMI, deserve the emphasis because they carry most of the weight. The job-type correlation is the practical anchor. Heavier manual work tracked with worse Sugaya grades even in identical twins, meaning load, not just biology, drives tendon breakdown.
Keep the caveats in mind. This is a small cross-sectional twin sample of 33 pairs, too few for full quantitative genetic modeling, so the 18% figure is an estimate rather than a fixed truth. It also complements, not contradicts, the gene-association literature confirming cuff disease is polygenic.