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The four muscles making up the rotator cuff originate on the shoulder blade (scapula) and insert via strong tendons onto the top of the upper arm bone (humerus). A common pneumonic we use to remember these muscles, also correlates to the order of which ones are most commonly injured: 'SITS':

1. Supraspinatus
   • Location: Lies on top of the shoulder blade, tucked under the acromion (the bony roof of the shoulder).
   • Main job: Starts (initiates) arm elevation (abduction) for the first 15-20 degrees. It is the most commonly torn rotator cuff tendon because it passes through a narrow space between the humeral head and the acromion, where it can get pinched.
   • Action: Abduction (lifting the arm out to the side).
2. Infraspinatus
   • Location: Covers the back of the shoulder blade.
   • Main job: The strongest external rotator of the shoulder. It turns the arm outward (e.g., when you cock your arm to throw or opening doors and cupboards).
   • Action: External rotation and helps stabilise the humeral head during overhead motions.
3. Teres Minor
   • Location: Small muscle just below infraspinatus.
   • Main job: Also an external rotator, working together with infraspinatus. It is injured less often but is important for fine control.
   • Action: External rotation and adduction.
4. Subscapularis
   • Location: Covers the front of the shoulder blade, but remains behind the ribs (the only cuff muscle on the front side of the scapula).
   • Main job: The primary internal rotator (turning the arm inward, like reaching across your body). It also acts as a strong anterior stabiliser to prevent the humeral head from sliding forward.
   • Action: Internal rotation and anterior stabilisation.

Together, these four muscles compress the humeral head into the glenoid like a golf ball on a tee, providing dynamic stability at the joint.

How Do Injuries Happen?

When speaking of muscle injuries in general, we tend to use ‘tear’ and ‘strain’ interchangeably. Effectively, a muscle injury has some grade of tearing within the muscle matrix. When considering rotator cuff injuries, strains may be low-grade mild tears, or complete ruptures and loss of integrity. Although they are independent muscles, the rotator cuff works in unison, which does mean that injury can happen to one or multiple muscles at a time. Again, there may be low grade tears across multiple muscles, or ‘massive tears’ when 2 or more muscles in the cuff are ruptured. It is important when considering shoulder pain that the mechanism of injury is established, as it can lead to clues around grading, specific muscle integrity and the management moving forward. Two main mechanisms cause injury:

1. Degenerative Tears
   • These can vary between mild fraying to complete ruptures, usually devoid of any sudden event.
   • Most common after age 40-50. Some literature suggests nearly 90% of our elderly population are living without 1 or more rotator cuff muscles due to degenerative tears.
   • Predisposed by years of repetitive overhead motion or minor impingement causing micro-trauma. Blood supply to the tendons also decreases with age, making healing harder.
2. Acute Traumatic Tears
   • Due to the high energy nature of traumatic tears, these are typically higher grade than minor fraying or their degenerative counterparts.
   • Sudden forceful injury: falling on an outstretched arm, heavy lifting, or dislocation (especially in people over 40 where degenerative changes may already be occuring).
   • Younger patients usually tear the cuff only with major trauma or during high-impact sports (wrestling and other contact sports).

A common pattern we see at Spectrum is long-standing degeneration; which makes the tendon weak; and a relatively minor event which causes the final tear.

Signs and Symptoms

Rotator cuff injuries can be extremely painful and debilitating, making them difficult to accurately identify amongst other diagnoses. Here are some key signs and symptoms that point to rotator cuff as the primary cause of pain:

• Pain on the outside (lateral) or front (anterior) part of the shoulder.
• Pain can sometimes radiate to the upper arm.
• Pain when sleeping on the affected shoulder, or when turning over in bed.
• Weakness and / or pain lifting the arm overhead.
• Weakness and / or pain in specific rotator cuff muscle actions.
• Visible muscle wasting / atrophy in longstanding tears.

Imaging

There are plenty of hands-on tests our Spectrum experts are knowledgeable in to help identify what is causing your shoulder pain. In some cases, we may wish to refer for further investigation via imaging:

• MRI: As usual, the gold standard for soft tissue related injuries. The MRI can best visualise the rotator cuff in great detail.
• Ultrasound: Not our first preference at Spectrum, however there are advantages to this imaging modality: it is quick, there is no radiation, and has the ability to dynamically assess the shoulder.
• X-rays: In some cases, X-ray may be used to investigate the shoulder. Whilst not commonly used for the purposes of assessing rotator cuff tears, there are some clues which indicate a tear has occurred. One example is a high-riding humerus, which would indicate loss in function of the rotator cuff to hold the upper arm in place in the glenoid fossa.

How Can Spectrum Help You?

Spectrum specialises in conservative care, meaning non-operative care; and in most cases, rotator cuff tears respond well. Here, we like to use a combination of hands-on and rehabilitation to help get you back to your best:

• Pain management: At Spectrum, we can use our advanced technology available to us, for example the Game Ready hot and cold contrast system, which blends the advantages of heat, cold and compression therapies.
• Manual therapies: such as dry needling, soft tissue massage, cupping, joint mobilisation and many more, are options to help you manage symptoms and restore function at the shoulder..
• Taping and protection: Modalities like K-taping and rigid taping can help prevent flare ups and manage symptoms during unavoidable work tasks, or important sports competitions.
• Rehabilitation: targeted exercises to strengthen the elbow, wrist and shoulder muscles are vital to returning to normal function, particularly as function can change down the chain with shoulder injuries.

In some cases, conservative care may not suffice. Spectrum can help lead you in the right direction for further management in these cases. Platelet-rich plasma (PRP) injections, where your blood is spun to concentrate healing factors and re-injected into the injury site can be beneficial. In some cases surgery is indicatd:, generally after significant trauma or in massive tears. In each case, surgical or non-surgical, there is a period of acute pain management and rehabilitation to return to normal function.