Why Shoulder Ultrasound Scans Don’t Tell The Full Story

MRIs, CT, and ultrasound scans have improved healthcare enormously, these imaging techniques are an important tool, but don’t give us the whole story. The tendency is to blame any pain on the structural abnormality seen in the scan. Both patients and clinicians make this mistake. (7)

• Studies have shown in a pain-free shoulder group with ages ranging from 40 -70 years, abnormalities were found in 96% of shoulders scanned. (1)
  
  
• Over 20% of the over 50-year-old group studied had muscle tears (with the frequency increasing with age). None had shoulder pain. This was seen as a normal consequence of ageing. (2)
  
  
• 50% of young elite baseball pitchers had damage to the muscles or cartilage in the shoulder joint with no effect on their performance (3)
  
  

Similar results have been found with MRIs for low back and neck and scans for knees. (5,4) Abnormal findings in the sample group of pain-free subjects. If pain were present there is a significant risk of those ‘pathologies’ being blamed for the presenting pain or injury. Just by taking the scan results as confirmation that the cause of pain and disability are the abnormalities seen in the investigation.

There can be a wide difference in report results by different reviewers for the same scan, particularly with MRIs for back pain. There is poor agreement between reports, (6) suggesting that opinions regarding pathological change can vary significantly. Ultrasound for shoulders shows a fair to good correlation between sonographers. (8)

Other studies have highlighted the importance of noting pathological changes compared to the prevalence in a matched population, so they sound less sinister (9) or noting changes in a less negative way (10). In our experience, negative reports can impact attitudes to injury and take a lot of effort to explain that they may not be relevant.

Scans are often ordered to identify the cause of shoulder pain, but it’s very confusing when scans come back clear with no structural abnormality reported. There are a multitude of causes that we see in the clinic that will not show on a scan, such as poor motor control, muscle weakness, overactivity or inhibition, nerve tension or compression, a referral from the neck, thoracic spine, or remote drivers to mention a few.

Our treatment experience and the research suggest that changes seen on a scan can have a very little connection with the pain people are experiencing and that the results of the scan itself are not significant unless there also is a comprehensive assessment, and a clinical reasoning process is used to find the main cause of the shoulder pain.

Ideally, if no ‘’red’’ or caution flags are raised on assessment (if so, immediate referral back to a GP or further investigation is warranted) a treatment plan can be formulated. In the early acute phase, a period of unloading or rest is appropriate. This then progresses to finding and treating the cause of the shoulder pain and dysfunction. A graduated exercise program is essential here to improve tolerance to ‘loading’ of the injured tissue. There is then a gradual increase in exercise resistance, repetitions, speed, and complexity and a return to full activity. We recommend that further investigation or scans be organised in conjunction with the treating doctor if there is slower than expected recovery.

In summary ultrasound for shoulder pain can be a valuable adjunct to treatment when referred appropriately. The findings of structural damage must be seen in the context of the clinical presentation rather than as a definite causal factor.

At Northwest Physiotherapy Group, we look at the whole person. You are not just the sum of the negative changes seen on scans. If you have pain or issues with your shoulder the experienced physios at NWPG look at all the possible causes rather than just the ultrasound results.