Diseases of the tendons in the upper limbs and their surrounding tissues – upper extremity soft tissue disorders, or UESTDs – are a common cause of upper limb pain. While the exact causes and development of these diseases are not known, some studies have linked obesity and diabetes to the prevalence of tendon disorders in the upper limbs.
Animal experiments as well as studies conducted with human tissue samples have found evidence of inflammation in tendons, suggesting that pro-inflammatory cytokines play a role in UESTDs. However, the significance of cytokines in this process has barely been studied, and the role of adipokines, which are secreted by fatty tissue, in these disorders has not been researched at all.
Obesity changes the blood levels of both cytokines and adipokines.
In his doctoral dissertation, Martti Rechardt, MD, studied the connection of metabolic and inflammation factors to shoulder pain and upper extremity soft tissue disorders. The study, focusing on shoulder disorders, involved 6,354 Finns of working age (from the Health 2000 survey conducted by the National Institute of Health and Welfare). The investigation of upper extremity soft tissue disorders involved 163 Finns who had sought occupational healthcare due to upper limb pain (data from the Finnish Institute of Occupational Health) and 42 healthy control subjects.
Approximately 16% of Finns of working age in the survey reported shoulder pain during the past 30 days. Through clinical examination, 3% of them were found to suffer from chronic rotator cuff syndrome. The patient data from occupational healthcare showed that the most common diagnoses were rotator cuff tendinitis and lateral epicondylitis, both of which were diagnosed in approximately one third of the cases. A fifth of the patients experienced pain with no specific diagnosis. A third of the patients reported either full or substantial recovery within three months.
BMI, waist circumference and type 2 diabetes were linked to shoulder pain in the population data, and waist circumference was additionally associated with chronic rotator cuff syndrome. Large waist circumference, low HDL cholesterol and elevated serum lipids were associated with upper limb pain.
“According to these results, obesity and diabetes are associated with shoulder pain and chronic rotator cuff syndrome, but the mechanisms underlying this association are currently not fully understood.<0} The cytokines circulating in the blood of an obese person may render the patient more sensitive to pain and promote inflammation in the tendon structures,” says Rechardt.
The dissertation can be accessed through the E-thesis service: https://helda.helsinki.fi/handle/10138/179228