Shoulder Injuries

What is the shoulder composed of?

The shoulder (shoulder girdle complex) is commonly thought to be made up of just one joint, but in fact there are 4 different joints that help the shoulder function. All 4 of these joints must be working properly to attain full motion of the shoulder. These 4 joints include:¹

• Glenohumeral- head of the shoulder in the socket
• Sternoclavicular- collar bone connecting to your sternum
• Coracoclavicular- shoulder blade to the collar bone
• Scapulothoracic- shoulder blade to the middle of your back

The majority of your motion (2/3rds) comes from the glenohumeral joint and a 3^rd comes from the scapulothoracic.¹ Conditions such as arthritis, causes the individual to use more shoulder blade motion than from the shoulder itself. The body is smart in that we try to avoid motions in areas that are painful, but then we start to rely on different areas to pick up the slack. This can lead to faulty movement mechanics that may lead to pain and discomfort.

The importance of the shoulder blade (scapula)

The scapula is an often-overlooked area for many healthcare practitioners. It helps to connect the shoulder to the skeleton. The scapula’s role is to¹

• Help stabilize the shoulder within the joint
• Allows for greater motion of the shoulder
• Serve as an area of attachment for 17 different muscles in the body!

In order for the scapula to work properly, a balance between different muscles in the front and back of the body are needed. Imbalances can also lead to faulty movement patterns that may lead to pain, discomfort, and/or poor performance.²

The role of the rotator cuff

This is the most well recognized area of the shoulder but is often not well understood and can place a lot of fear in the everyday person. The rotator cuff is a group of 4 different muscles that attach from the shoulder blade to the head of the shoulder (humeral head).² They each have an important role in stabilizing the shoulder at rest or with activity and help to move the shoulder in different directions.^2,3

These 4 muscles include:²

1. Supraspinatus- raises the arm such as with reaching overhead
2. Infraspinatus- turns the shoulder outward as in starting a lawnmower
3. Teres Minor- also turns the arm outward but more so with the arm overhead such as combing your hair
4. Subscapularis- turns the arm inward such as reaching behind your back to fasten a bra or throwing a baseball

Shoulder injuries

There are a lot of different shoulder injuries out there that can impact your everyday function. Here are just a few.

1. Rotator Cuff Injury

As described above, the rotator cuff is very important for daily shoulder motion and stability. Injuries to this group of muscles comes in all shapes and sizes and can occur from a fall or from overuse.³ Tears can range in a variety of different sizes and can be treated most commonly with Physical Therapy or surgery depending on the patient’s history and extent of the tear.³ One thing to note is that after a certain age, most of us will have some sort of tear in our rotator cuff muscles. This can be a normal part of aging and does not necessarily mean you will need surgery.

Overuse can occur in those who do repetitive overhead motions of the shoulder or recently participated in a more strenuous job or recreational activity (ex. starting tennis 7 days a week without playing before).³ Often times our best remedy for treating this is taking a step back from the activity and then slowly building back up.

2. Shoulder impingement (Subacromial Pain Syndrome)

There are several different types of shoulder impingement. The most commonly recognized hypothesis is that impingement occurs when the rotator cuff, shoulder bursa, or tissue in the shoulder is compressed between the humeral head and shoulder blade/collarbone.⁴ This can be due to many reasons including the shape of our shoulder blade, weakness of the shoulder muscles causing increased movement of the humeral head, and bony changes within the shoulder complex.⁴ Although the cause is still up for debate, the condition is defined as a non-traumatic, shoulder problem that causes pain localized to the front of the shoulder (acromion) that often worsens with lifting of the arm.⁴

3. Frozen Shoulder (Adhesive Capsulitis)

To this day there is still no definitive consensus for why this occurs. Some people are more at risk including those with a history of thyroid issues and diabetes.⁵ The condition is characterized by the development of adhesions and thickening, of the shoulder capsule.⁵ People often complain of a loss of motion and increased pain without any specific event they can associate with this issue.

4. A neck issue (cervical referral/radiculopathy)

Many issues related to the neck can be felt in the shoulder. This can include many different structures in the cervical spine that are perceived in the shoulder or below.⁶ One tell-tale sign for if an issue in the shoulder is in fact coming from somewhere else such as the neck, is if symptoms are felt past the elbow. Most often, issues perceived below the elbow are in fact caused by somewhere other than the shoulder.

References

1. Neumann, D. A. (2016). Kinesiology of the musculoskeletal system (3rd ed.). Mosby.
2. Reinold MM, Escamilla RF, Wilk KE. Current concepts in the scientific and clinical rationale behind exercises for glenohumeral and scapulothoracic musculature. J Orthop Sports Phys Ther. 2009;39(2):105-117. doi:10.2519/jospt.2009.2835
3. Weber S, Chahal J. Management of Rotator Cuff Injuries. J Am Acad Orthop Surg. 2020;28(5):e193-e201. doi:10.5435/JAAOS-D-19-00463
4. Diercks R, Bron C, Dorrestijn O, et al. Guideline for diagnosis and treatment of subacromial pain syndrome: a multidisciplinary review by the Dutch Orthopaedic Association. Acta Orthop. 2014;85(3):314-322. doi:10.3109/17453674.2014.920991
5. Kelley MJ, Shaffer MA, Kuhn JE, et al. Shoulder pain and mobility deficits: adhesive capsulitis. J Orthop Sports Phys Ther. 2013;43(5):A1-A31. doi:10.2519/jospt.2013.0302
6. Neck Pain Guidelines: Revision 2017: Using the Evidence to Guide Physical Therapist Practice. J Orthop Sports Phys Ther. 2017 Jul;47(7):511-512. doi: 10.2519/jospt.2017.0507. PMID: 28666402.