There are several different shoulder conditions and with that several different causes to those conditions. Shoulder pain can arise from the joints and muscles directly related to the area, it can be radicular as in a pinched nerve from the neck, or it can be a referral from another organ in the body.
Simply put: shoulder pain can be complex and debilitating as we use and rely on our shoulders for most every activity we do. To fully understand shoulder pain, let’s first look at what structures are involved in making up the shoulder girdle and how they function in the human body.
Causes of shoulder pain can be broken down into a couple different categories:
> The Shoulder Dysfunction Continuum
There is a progression of muscular imbalances in the shoulder girdle that, if left untreated, will progressively worsen and ultimately end up with rupture of the rotator cuff. This is non-traumatic and typically affects the desk worker as it is driven by poor posture and overuse. Let me explain: The continuum goes like this: Scapular Dyskinesis to Subacromial Impingement Syndrome to Rotator Cuff Tears to Rotator Cuff Rupture. It is important to note that this is COMPLETELY PREDICTABLE
- Scapular Dyskinesis: this is simply malposition of the scapula and results from poor posture. As the poor posture is left unaddressed overuse begins to occur and leads to compensation and ultimately alteration of the normal biomechanics of the shoulder girdle. This is generally not a painful condition but more a postural observation that has a characteristic pattern of tight and weak muscles. It is also a good predictor of future problems!
- Subacromial Impingement Syndrome (SAIS): As the muscle imbalances in the shoulder girdle continue, the muscles along the inferior tip of the shoulder blade become weaker while the muscles of the anterior shoulder become stronger which allows the shoulder blade to “roll forward”. This creates an impingement on the Supraspinatuis tendon of the rotator cuff (image(s) here). This will create pain in the anterior shoulder especially when trying to lift or internally rotate the arm.
- Rotator Cuff Tears: If the problem is further ignored this can lead to partial- or full-thickness tears of the rotator cuff muscles. This causes further breakdown and dysfunction of the muscle tissues and can be quite painful with even simple tasks.
- Rotator Cuff Rupture: This is the ultimate result of ignoring the problem. The muscle fibers will continue to tear until it completely ruptures apart. This results in complete loss of function of the muscle and requires surgical repair.
> Other Mechanical Causes
- Cervical Radiculopathy
- Peripheral Neuropathy (Thoracic Outlet Syndrome)
- Injury to Spinal Accessory Nerve (Cranial Nerve 11), The Long Thoracic Nerve or Suprascapular Nerve
3. Specific Joint Pathology
- AC Joint Separation
- AC Joint Instability
- AC Joint Arthrosis
- Labral Injury
- GH Joint Internal Derangement
- GH Joint Instability
- AC Joint/GH Joint DIslocations
- Fractures of the collarbone, shoulder blade or upper arm
4. Other Causes
- AutoImmune Disease
- Bone Spurs
- Referred Pain from Gallbladder or Heart Attack
- Torn Cartilage or Ligaments