Apple farmers demonstrate a higher prevalence of rotator cuff tears: magnetic resonance imaging-based cross-sectional cohort study in a rural Japanese population

Abstract

Background

Limited data are available on how fruit tree farmers are at risk for rotator cuff tears (RCTs). Using mobile magnetic resonance imaging, this study aimed to clarify the prevalence of RCTs in a rural Japanese area where a large proportion of the population works is apple farming.

Methods

A total of 371 participants ≥40 years old were recruited (average age: 59.3 years, 225 females) and underwent dominant-side shoulder magnetic resonance imaging. RCT was defined as full-thickness tear on imaging. Shoulder function was evaluated by the Constant–Murley Score. Regarding the participation in apple farming, full-time farming was defined as participating 5 days or more per week; part-time farming was defined as participation less than 5 days per week; non-apple farming was defined as not participating in apple farming at all.

Results

Sixty-four participants (17.3%) had RCTs. The prevalence of RCTs was 2.8%, 7.8%, 25.0%, and 34.2% in individuals in their 40s, 50s, 60s, and ≥70 years old, respectively. The receiver operating characteristic curve revealed that 60 years was the optimal age cut-off to detect RCTs (area under the curve: 0.751, 95% confidence interval (CI): 0.690-0.812) Logistic regression analysis demonstrated that the prevalence of RCTs in farmers ≥60 years old was 6.7 times higher (95% CI: 3.3-13.3) than in those <60 years old. Participants with RCTs showed a significantly worse Constant–Murley Score than those without. Twenty-nine farmers (7.8%) had full-time participation, 137 farmers (36.9%) had part-time participation, and 205 (55.3%) were non-apple farmers. Twelve full-time farmers (41.1%) had RCTs; the corresponding values for part-time and non-apple farmers were 26 (19.0%) and 26 (12.7%), respectively. Logistic regression analysis demonstrated that full-time farmers had a 3.8-times higher odds ratio of RCTs compared to non-apple farmers (95% CI of odds ratio: 1.4-10.0).

Conclusion

The prevalence of RCTs increased with age. Affected participants showed worse shoulder function than those without RCTs. Full-time farmers showed a higher odds ratio of RCTs compared to non-apple farmers. This indicates that frequent participation in fruit tree farming is associated with the development of full-thickness RCTs.