Causes of Unequal Shoulders

Shoulder joint attaches the upper limb to the thorax. It is composed of several joints and muscles acting around it. If you think your shoulders are not equal, it could be due to several reasons.

1.      I could be totally normal – Even though humans appear symmetrical at a glance, there could be many differences in the right side and in the left side. Most of the people’s dominant side is said to be a little bigger than the non-dominant side. This is a completely normal phenomenon.

2.      Axillary nerve damage – Unequal shoulders could be a result of abnormality of the muscles in the shoulder joint area. One such muscle which frequently get affected is the deltoid muscle. Deltoid muscle makes up the most of the lateral aspect of the arm. Wasting of this muscle results in flattening or reduction of the bulge of the shoulder. 

How does the Deltoid muscle get wasted?

Every muscle in our body is supplied by a nerve, which carries the signals which command the muscle to contract. More the muscle contracts, bigger the muscle becomes. Therefore, if you are using one muscle more often, it becomes bigger. That’s how the body builders increase their muscle mass. On the other hand if you are not using your muscle it gets atrophied (reduce in mass)

So, the deltoid muscle also gets atrophied when it is not contracting any more. This occurs when the nerve supplying the deltoid muscle, the axillary nerve is not working. The axillary nerve gets damaged in anterior shoulder dislocations. Therefore, if you have a history of shoulder dislocation, then the most likely cause of your unequal shoulder is the axillary nerve damage.     

Related articles:

SIGNS OF AXILLARY ARTERY DAMAGE

Signs of Axillary Artery Damage

Axillary nerve damage is a common complication of the anterior shoulder dislocation. It is because of the close proximity of the axillary nerve to the shoulder joint. It can be confirmed by looking for the following signs.

1.      Wasting of the shoulder – To detect this, compare the affected shoulder with the normal one. Does the affected shoulder look thin and fat? Then it is due to wasting of the deltoid muscle, which is supplied by the axillary nerve.

2.      Loss of sensation over the regimental badge area- Regimental badge area is located in the lateral part of the upper aspect of the arm. This area is supplied by the axillary nerve and therefore, absence of sensation over that area indicates damage to the axillary nerve.

                                                        

RELATED ARTICLES

·         COURSE OF THE AXILLARY NERVE

Diagnose yourself: Pain in Shoulder: Examination of the Shoulder

Several diseases can affect the shoulder joint and these diseases can present with various signs and symptoms. 

DISEASES AFFECTING THE SHOULDER JOINT

Pain is one such symptom. It could be of two types.

·         Pain arising within the shoulder joint – this type of pain is felt anterolaterally

·         Referred pain

If you have pain in your shoulder, follow the following 3 steps to diagnose what it is.

1.      Look

2.      Feel

3.      Move

Look

Look at your shoulder carefully to detect following.

1.      Look at the Skin – Look at the skin for scars, bruises, wounds. Even a bruise can be indicative of an underlying fracture of the bone.
2. Compare the painful shoulder with the other one. Does it appears smaller/flatter than the other? This is due to wasting of the deltoid muscle. This muscle gets wasted when the nerve supplying it is damaged. That nerve is the axillary nerve and it commonly gets damaged in anterior shoulder dislocation

SHOULDER DISLOCATION? IS THE AXILLAY NERVE DAMAGED? SIGNS  OF AXILLARY NERVE DAMAGE

            Rotator cuff injuries also cause wasting of rotator cuff muscles, which would be visible.

3.      Is the normal shoulder contour is lost? Then it might be due to dislocation. If it is anterior shoulder dislocation there will be an anterior bulge and a squared-off shoulder.

FEEL

1.      Is the pain generalized or localized?

a.      Generalized pain – arise from neck or the shoulder joint

b.      Localized pain- from acromioclavicular joint

2.      Check the skin sensation – Is there a loss of sensation over the upper part of the lateral aspect of the arm?  This area is also called regimental badge area. This also indicates axillary nerve damage.
 

Regimental Badge Area

 

MOVE

Movements of the upper arm occur in two points. They are at,

1.      Shoulder joint movements

2.      Scapulothoracic joint movements

If the pain is coming from the shoulder joint itself the patient will be moving the arm from the scapulothoracic joint. Follow the following steps to assess the movements of the shoulder joint.

1.      Start in the neutral position.

                                                              i.      Arms by the sides

                                                            ii.      Elbows extended

                                                          iii.      Palm facing forwards

Neutral Position of the body

2.      Stabilize the scapula

                                                              i.      Place the thumb over coracoids process

                                                            ii.      Place the other fingers of the same hand over the spine of the scapula

3.      Forward flexion

                                                              i.      Keep the elbow extended

                                                            ii.      Raise the hands as to touch the roof

4.      Extension

5.      Abduction (painful arc test)

                                                              i.      Raise the arms sideways as to touch the roof

                                                            ii.      First 60⁰ – glenohumeral

                                                          iii.      Then – glenohumeral and scapulothoracic

                                                           iv.      Last – entirely scapulothoracic

                                                             v.      Impingement syndrome – presence of pain from 60⁰ – 120⁰   It indicates rotator cuff pathology.

                                                           vi.      Jobe’s test is also used to identify impingement syndrome.

6.      Adduction

                                                              i.      Touch the other shoulder tip

7.      Internal rotation

                                                              i.      Touch the back with the dorsum of the hand

                                                            ii.      Raise the hand up the back as high as possible

                                                          iii.      A normal person can raise up to 7the thoracic spine level

8.      External rotation

                                                              i.      Bend the elbow to 90⁰

                                                            ii.      Keep the forearm mid prone

                                                          iii.      Now separate the hands

9.      Apprehension test for anterior shoulder instability.

                                                              i.      Flex the elbow to 90⁰

                                                            ii.      Abduct the shoulder to 90⁰

                                                          iii.      Externally rotate the shoulder

Diseases Affecting the Shoulder

Following are some orthopaedic conditions that affect the shoulder joint. If there is something wrong with your shoulder, the following conditions are the most likely causes. How to differentiate each of the following will be discussed in my later posts.

Diseases affecting the bones –

·         Fractures – fractures in clavicle, scapula, neck of the humerus

·         Neoplasm – secondary deposits

Diseases in the joint

·         Dislocation

·         Osteoarthritis

·         Rheumatoid arthritis

·         Septic arthritis

·         Tuberculous arthritis

·         Adhesive capsulitis (frozen shoulder)

Diseases affecting the muscles and the tendons

·         Rotator cuff tears

·         Impingement syndrome

·         Supraspinatus tendinitis

Congenital diseases

·         Kippel-Feil Syndrome

Neurological

·         Winged scapula

Referred Pain

·         From the cervical spine – cervical spondilosis and pancaost tumour

·         From Heart 

·         From the mediastinum

·         Irritation of the diaphragm – could be both due to pleurisy or ascites