Sarasota, FL (WorkersCompensation.com) – Workers who spend much of their time lifting and carrying are at risk of severe shoulder injuries that may require surgery. A new study out of Denmark suggests organizations would be wise to find ways to alleviate these activities, as well as pushing and pulling.
Researchers analyzed data on thousands of working adults with high exposure to certain shoulder-related activities who had undergone surgery for subacromial impingement syndrome (SIS), a common disorder of the shoulder.
“We found an increased risk of surgery for SIS for both exposure duration and intensity of lifting/carrying loads ≥10 kg (about 22 pounds) and pushing/pulling loads ≥50 kg (roughly 110 pounds),” the researchers wrote in the BMJ Journal Occupational and Environmental Medicine. “There were higher risks for lifting/carrying loads compared with pushing/pulling loads. After 10 years with high intensity of lifting/carrying loads, the risk was almost three times higher among the most exposed compared with the non-exposed. For pushing/pulling loads, there was a maximum of 72% increase in risk compared with the non-exposed.”
SIS, also known as ‘swimmers shoulder,’ is an inflammation and irritation of the rotator cuff tendons as they pass through the subacromial space, causing pain, weakness, and reduced range of motion. It encompasses a range of pathology, including rotator cuff tendinosis, subacromial bursitis and calcific tendinitis. Complications from it include rotator cuff degeneration and tear, adhesive capsulitis, cuff tear arthropathy and complex regional pain syndrome, according to experts.
Most SIS cases resolve with conservative care. Surgery may be required for more severe cases, at a cost between $8,000 and $18,000 and a typical recovery period of six to eight weeks.
The prevalence of SIS is about 2 percent to 8 percent in the general working population, and up to 10 percent among workers with higher exposures, such as slaughterhouse workers, fish processors, sewing machine operators and manufacturing and trade workers.
Previous studies have established associations between occupational mechanical exposures and SIS in systematic reviews, with highest risks seen for forceful shoulder exertions. The researchers were specifically interested in the effects of other force activities, including lifting, carrying, pushing and pulling.
They conducted a register-based cohort study from 2003 to 2008 consisting of persons born in Denmark between 1933 and 1977 with at least five years of work experience. A Danish National patient registry identified 14,188 who had undergone SIS surgery.
Among those included, the authors created three intensity-specific exposure duration variables – low, medium and high, depending on weight loads and times per day of the activities. The researchers also summed up the number of years in each exposure category for a 10-year time window.
The adjusted odds ratio increased with exposure duration and intensity for both groups – lifting/carrying and pushing/pulling.
The ratios among the lifting/carrying workers were:
- Low – 1.78
- Medium – 2.52
- High – 2.96
For pushing/pulling the ratios were slightly less:
- Low – 1.44
- Medium – 1.68
- High – 1.72
“These results indicate that among the different force activities, lifting and carrying loads, in particular, should be considered hazardous,” the authors wrote.
The researchers were also looking to provide insight into safe exposure intensities that do not increase the risk of surgery for SIS – even after prolonged exposure duration.
“This was not possible as all exposure to lifting/carrying and pushing/pulling loads above minimal lead to an increase in risk of surgery for SIS either straight away for lifting/carrying loads, or after only a few years with pushing/pulling loads,” they said. “In the search for exposure thresholds, the low exposure groups (lifting/carrying loads: >0.0–0.0–0.0–0.0–0.0–0.0–
Organizations looking to keep affected workers safe should look for ways to reduce exposure to lifting and carrying loads, the writers advised. Also, lifting/carrying and pushing/pulling loads should be included in the assessment of ergonomic exposures for the shoulder, along with other known risks – shoulder force, repetitive shoulder movements and upper arm elevation.
“In clinical practice workers with shoulder pain should be advised to avoid or at least reduce lifting/carrying and pushing/pulling loads to maybe alleviate their shoulder pain,” they concluded. “At the workplace there are several technical solutions to reduce lifting/carrying and pushing/pulling loads.”