Arthralgia - shoulder joint inflammation
Arthralgia is shoulder joint pain (or any other joint) where arthritis is inflammation within the joint. Acute inflammatory joint lesions may occur and show any characteristic of inflammation. Possible signs could be pain (may be throbbing), redness, swelling, local heat in the shoulder joint and a loss of functional movement of the shoulder.

Infection of The Shoulder Joint
Generally may cause arthritis which is unilateral with redness, swelling, heat around the joint and irritated or burning pain of the shoulder.

Restricted Movement of the Shoulder Joint
Restriction of any joint may be caused by mechanical defects, soft tissue contractures, joint effusion, muscle pain, muscle spasms or muscle paralysis.

Shoulder Joint Dislocation
This occurs when all opposition between the ball and socket joint and the muscles/ligaments is lost allowing a subluxation of the joint.

Swelling of Shoulder Joint
There may be a joint effusion causing excess synovial fluid within the shoulder joint. Firm palpation with a finger will reveal a boggy feeling of the shoulder. There may be displacement of the fluid which causes extra swelling to develop in proximal areas to the shoulder. This can be detected by a clear sense of fluctuation between two palpating fingers. Joint swelling may also be caused by pus or haemorrhage within the shoulder.

Acromioclavicular Arthritis
This type of shoulder joint pain will give rise to tenderness over the acromioclavicular joint, especially when the arm is brought in front and across the chest (adduction). This joint pain suggests arthritis in the acromion and calvicular joint. The pain will often be aggravated with a shrugging movement of the shoulders. This may be due to direct trauma to the shoulder girdle.

Tendonitis of the Shoulder - Bicipital or Rotator Cuff Tendons

Bicipital Tendonitis
Tenderness over the long head of the biceps where a groove can be felt. When pressure is added to this groove general pain will be felt. Shoulder pain will also be felt when the shoulder is flexed and the arm is supinated against resistance.

Rotator Cuff Tendonitis
Shoulder joint pain originating over the rotator cuff when the elbow is passively lifted posteriorly or with a "dropped arm" maneuver. If pain occurs with this type of shoulder movements, it generally points at tendonitis of the rotator cuff. This type of shoulder pain is common after the age of 50 but is found in all ages. The shoulder pain begins with localized supraspinatus tendonitis, extending to other rotator cuff tendons insertions and subacromial bursa. This type of shoulder disorder may lead to a frozen shoulder from adhesive capsulitis. Adhesive capsulitis arises from impingement of the rotator cuff against the undersurface of the acromion and coracromial ligament. This condition leads to inflammation and degeneration of the shoulder muscles and tendons.

Subacromial and Subdeltoid Bursitis
This type of shoulder joint pain will radiate anterior and superior to the aspect of the shoulder and be greatly aggravated when the arm is raised overhead. This pain suggests subacromial bursitis. There may also be shoulder joint pain and tenderness anterolateal to the acromion, in the hollow recess formed by the acromiohumeral sulcas. This type of pain is generally due to overuse from repetitive motion like throwing a ball in base ball or swimming. The joint pain is caused by impingement of the acromion, acromioclavicular ligament and coracoid process against the underlying bursa. This will result in inflammation of the burs giving rise to shoulder pain in and around the joint.

References

Welsby, P.D.
Clinical History Taking and Examination
An Illustrated Colour Test, Second Edition, @002
Churchill Livingstone

Wallach, J.
Handbook of Interpretation of Diagnostic Test
1998, Lippincott-Raven

Mosby Medical Encyclopedia
Revised Edition 1996