Does the size of Rotator Cuff Tears Relate to the Amount of Pain Experienced?

In 2016 I attended the brilliant Musculoskeletal and Sports International Master Class for physiotherapists by Dr Chris Littlewood. Dr Littlewood was at that time a Senior Research Fellow with the University of Sheffield. This event was organised by the Australian Physiotherapists Association. New treatment ideas were presented for physiotherapists treating shoulder injuries, and I have subsequently incorporated some of these into my clinical practice. It is interesting to note that although it is likely that 99% of physiotherapists in Australia assess, diagnose and treat people with shoulder injuries every day, many people do not consider having a consultation with a physio for their shoulder injury.

My experience since making these changes is that my patients with shoulder pain and dysfunction are improving more so than before. As many patients with shoulder pain present with ultrasound images and associated reports indicating a tear of their tendons in the shoulder, I felt the need to create this blogpost to help them understand the implications of these reports. It also helped me to reflect more on what I had learnt at the seminar. This article concentrates on shoulder injuries related to the rotator cuff.

What is the basic anatomy of the shoulder?

Typically muscles change into tendons to join onto bones. There are many muscles around the shoulder, but a sub-set of four of these are called the rotator cuff muscles. Many will be familiar with their names: supraspinatus, infraspinatus, subscapularus, and teres minor. In general these muscles & their tendons have two attachments, one being closer to the middle of the body and is called the proximal attachment, and the other being further from the middle of the body and is called the distal attachment. These four muscles have a distal attachment on the arm bone, which is called the humerus.

The tendons can be thought of as thick ribbons of varying widths. A tear may therefore cut through only part of the thickness of the tendon, or the entire thickness of the tendon, being called partial-thickness tears or full-thickness tears respectively. When a tendon is completely torn, the proximal remnant of the tendon may pull back towards the middle of the body as it is no longer anchored distally. This pulling back is called retraction. The amount of retraction that develops appears to relate to the size of the tear and how long ago it occurred.

How to describe a rotator cuff tear?

Full-thickness tears have often been measured and graded according to the system of DeOrio and Colfield (1984). Their system was based on the anterior poster length of the tendon that was torn off the humeral head as measured during surgery. Grading was said to be: small if less than 10 mm, medium if between 10 and 30 mm, large between 30 and 50 mm, and massive if more than 50 mm.

Another system was devised by the Southern California Orthopaedic Institute. Their rotator cuff tear classification system graded complete tears as follows:

  • CI A small complete tear, such as a puncture wound;
  • CII A moderate tear (usually less than 20 mm) that only involves one tendon and no retraction of that tendon;
  • CIII A large tear (usually 30 to 40 mm) with little retraction;
  • CIV A massive tear involves more than two rotator cuff tendons, often with retraction and scarring, and often an L shaped tear.

How common are shoulder tears?

Studies have shown that the prevalence of shoulder tears, both partial- and full-thickness tears, in asymptomatic patients (ie. patients without any symptoms) is over 50% in people older than age 60 years, and 80% in those older than 80 years. These tears may have come about through various means, some of which may have been traumatic (e.g falls) and some non-traumatic (such as wear and tear).

What is the pain level and types of rotator cuff tears?

Many of us are accustomed to considering the amount of pain as being related to the amount of visible damage. It is normal to think that a person with a small gash to their forearm will have less pain than a person with a large cut. However, we are also aware that sometimes a small cut to some areas of the body, like a paper cut to a finger, can generate a lot more pain than we expect. What is really interesting is that the presence and even the magnitude of rotator cuff tendon tears appears to have very little relationship to the amount of pain experienced. Here is some of the evidence supporting this concept:

A 2011 research publication concerned 211 people that had 283 shoulders with full-thickness tears visible through ultrasound imaging. Surprisingly, nearly two-thirds (65.4%) of the shoulders did not cause the person to experience any symptoms of pain or disability. It was noted though that the presence of tears in the dominant arm had some association with symptoms.

As a physiotherapist I have noted that the presence of physical signs of damage do not always cause pain or decreased function. It seems that shoulder injuries involving rotator cuff tears often fit into this scenario. The good news is that although the physical presence of a tear is often not relevant, other factors are, and these usually respond favourably to physiotherapy treatment.

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