Shoulder Anatomy: Clavicle, Scapula and Humerus, These bones make 5 articulations, Sternoclavicular, Acromioclavicular, Glenohumeral, Scapulothoracic, Subacromial space. Yhe Glenohumeral joint has greater range of motion than any other joint. The end of the scapula called the glenoid meets the head of the humerus to form a flenohumeral cavity that acts as a flexible ball and socket joint. The joint cavity is cushioned by articular cartilage covering the head of the humerus and of the glenoid. The joint is stabilised by a ring of fibrous cartilage surrounding the glenoid called the labrum. There are at least 30 muscles that provide support for the shoulder complex.

Ligaments....are the main source of stability for the shoulder, they help hold the shoulder in place and keep it from dislocating. These ligaments of the shoulder complex are:

The rotator cuff muscles are important in shoulder movements and in maintaining glenohumeral joint (shoulder joint) stability.[1] These muscles arise from the scapula and connect to the head of the humerus, forming a cuff at the shoulder joint. They hold the head of the humerus in the small and shallow glenoid fossa of the scapula.

During abduction of the arm, the rotator cuff compresses the glenohumeral joint, a term known as concavity compression, in order to allow the large deltoid muscle to further elevate the arm. In other words, without the rotator cuff, the humeral head would ride up partially out of the glenoid fossa, lessening the efficiency of the deltoid muscle. The anterior and posterior directions of the glenoid fossa are more susceptible to shear force perturbations as the glenoid fossa is not as deep relative to the superior and inferior directions. The rotator cuff's contributions to concavity compression and stability vary according to their stiffness and the direction of the force they apply upon the joint.
During abduction of the arm, the rotator cuff compresses the glenohumeral joint, a term known as concavity compression, in order to allow the large deltoid muscle to further elevate the arm. In other words, without the rotator cuff, the humeral head would ride up partially out of the glenoid fossa, lessening the efficiency of the deltoid muscle. The anterior and posterior directions of the glenoid fossa are more susceptible to shear force perturbations as the glenoid fossa is not as deep relative to the superior and inferior directions. The rotator cuff's contributions to concavity compression and stability vary according to their stiffness and the direction of the force they apply upon the joint.

1) Rotator cuff tear/impingement-External rotation is weak / supraspinatus is weak / ++++ve impingement sign.

Impingement-Bursa and rotator cuff impinge between humeral head and acromion. Pain with overhead activities. Pain at night. Pain often radiates down arm to elbow. The rotator cuff holds the head of the humerus in its socket when performing overhead functions. As well is peing responsible for extenal and internal rotation of the humerus. When injured or fatigued the deltoid unapposed will therefore pull the humeral head upwards and cause impingement between the rotator cuff and the acromion.

Rotator cuff tears are very common, incidence increases vwith age.Diagnosis: Drop arm sign-The patient loses control of the arm when asked to adduct the arm slowly from a height. A patient may still have a rotator cuff tear if the sign is absent. Sensitivity 10%, Specificity 100%.
SERI tests: weakness in suoraspinatis, weakness in External rotation, and a positive Impingement sign.
Special points of interest: X-rays and ultrasound are the best investigators of a suspected rotator cuff repair. Acute, full theickness rotator cuff tears are best treated with surgical repair.

Less power in external rotation + loss in power in supraspinatus + Impingement in EER or IR then 98% Rotator cuff tear. If any 2 are positive then 98% cuff tear. If only 1 positive need further imaging.

2) SLAP lesions: Superior Labrum Anterior Posterior lesions involve the partial detachment of the labrum from the rim of the glenoid labrum from the rim of the glenoid cavity. SLAP lesions are classified both on their anatomical location and their size or severity. As to the repair procedure, the detached labrum is reattached to the glenoid rim using one or more bioabsorbable tackes.

3)Biceps injuries: Distal biceps ruptures, predisposition Male 100:1, 80% dominant side, average age 50 yrs. Mechanism of injury-acute extension force against agonist contracture, with a force > 40 kg with the elbow flexed at 90 degrees.
Classification: (A) Strain (B) Partial rupture (C) Complete rupture at the tuberosity.

Diagnosis: history of sudden tearing, dull ache persists, cosmetic complaints, weakness and pain (partial injury).
Physical findings: Ecchymosisn (skin discoloration caused by the escape of blood into the tissues from ruptured blood vessels). Defect. Tenderness. Weakness in flexion and or supination.
Repair: Acute complete disruption operative repair-suture to brachialis, interposition graft hamstrings.
Non-operative satisfactory results in 50% of patients. Avoids the risks of surgery, indicated in the elderly , non-dominant extremity. Usaually resultsin 40% loss of supination strength, 30% flexion strength deficit.

4)GLEN lesion Ganglion cyst arising from the superior Labrum with Entrapment of the inferior branch of the suprascpular Nerve. Suprascapular nerve entrapment can be caused by: Direct or indirect truama # or dislocation, Entrapment beneathe the superior transverse scapula ligament at the suprascapulaar notch. Compression by osteochonfroma or malignant tumour. Compression by ganglion cyst. Ganglion cyst arises from the posteriir-superior glenoid labrum.

Cause of the cyst has not yet been claerly defined, but the underlying pathology seems to be a labral tear, especially posterior type II SLAP lesions. Entrapment by ganlion cyst can lead to weakness and wasting of the infraspinatus muscle.

5) Shoulder pain in swimmers An estimated 100 million participants enjoy swimming at al ll levels. Swimming has nio impact activity and few inherent risks except for over use problems. Stroke characteristics inswimming have 4 phases: reach/catch/pull/recovery. Arm action provides the main (75%) propulsion in all strokes except breaststroke.

Elite swimmers rely on their shoulders for an average of 13,000metres per week. In addition competitive swimmers swim six days per week over a 10 month period, attaining approximately 2 million strokes per yearExtremes of the shoulder movement during swimming tend to cause glenohumeral (GHJ) laxity and these repeated stresses may result in cumulative microtrauma within the shoulder joint. The repetitive nature of swimming apparently predisposes the shoulder to mechanical and anatomical deficiencies which may lead to a spectrum of overuse injuries such as an undesirable increase in joint laxity, tendonitis and impingement of the rotstor cuff.

6)AC joint pain

7)Frozen shoulder/ Adhesive capsulitis: Functional anatomy- the surface area of the humeral head is two to four times that of the glenoid. The diameter of the humeral head is nearly twice that of the glenoid when measured in the transverse plane. This lack of articular contact contributes to the inherent instability of the gleno-humeral joint. Stability of the joint is provided by the surrounding musculature, by the fibro-cartilaginous labrum which creates a more conforming surface to the glenoid and by the shoulder capsule. Adhesive Capsulitis has been classified into primary(idiopathic) and secondary types. Primary cuses occur spontaneously. Secondary cases commonly develop in response to trauma to the upper extremity, upper exremety immobilisation , abnormal shoulder mechanics. While the defiinitive aetilogy of this condition is unknown, adhesive capsulitis has been reported to have associations with other conditions, including cervical spine disease , diabetes mellitus, rheumatoid arthritis, infectious myocardial infarctionand pulmonary cancer.occurs 40-60 yrs of age, Females more prevalent tham males, left shoulder more than right. Pathology involves fibrosis and thickening of the glenohumeral capsule. The condition is painful but self limiting with the average duration of symptoms 2.5 years. External rotation is decreased.

Adhesive capsulitis has been reported to have associations with other conditions specifically cervical pain 25%, calcium deposits 10%, diabetes 6%.

Pathology: There is an increased hypervascular synovium, in long term cases there was a significant fibrosis, hyalinzation, and fibrinoid degeneration in the latter phases of the disease in the sub-synovium capsule.

Operative observations of adhesive capsulitis.

• The capsule, synovial tissue and rotator cuff are thickened, fibrotic, contracted and closely adherent to the humeral head.
• The coracohumeral ligament and rotator interval are thickened, fibrotic and contracted and the humeral head is held tightly against the glenoid fossa.
• Inflammatory changes affect the synovium, bursae, rotator cuff and biceps tendon.
• The long head of biceps becomes stenosed in the bicipital groove.
• Articular surface changes affect the humeral head and glenoid fossa.
• Partail and full thickness tears are observed in the rotator cuff.
  
  

Calcific tendinitis-this is a painful condition of unknown aetiology, the calcific lesion develops in the substance of the rotator cuff tendon, most often in the supraspinatus.The precalcific stage is when fibrocartilaginous transformation, tenocytes converted into chondrocytes. Further progression results in vascular ingrowth, young fibroblasts, leading to type III collagen then type I collagen.
Clinical presentation "Acute Calcific Tendinitis" very painful especially with shoulder motion, treated with NSAID's + corticosteroids. Non-reponsive the indicated for surgical excision.

8)Instability

9)Gleno-humeral joint arthritis is another cause of shoulder pain and stiffness.

10) Arthritis

Apoptosis: Programmed cell death

Tennis elbow: Tendinopathy, degenerative, epicondylosis-extensor carpi radialis brevis.


11) Shoulder tendinopathy: Tendon disease: micro-tear causes tenocytes to secrete collagenases that decay fibrils causing tears. Overuse causes "proteoglycosis" caususes increased pain in tendon. There also neo-vasularisation with rupture of collagen.Aggrecan/ Bioglycan form proteoglycans.
Rx- Cortisone injections-used for decades, give short term pain releif, weaken the tendon, Symptom releif, Releive impingement, associated with tendon rupture.

What other injection options are there:
Prolotherapy-irritant(eg dextrose)
Deliberate tendon irritation
Autologous blood/PRP-Platelet Rich Plasma
Acetic acid iontophoresis for plantar fasciitis
|Aprotinin/collagenase inhibitors
Actovegin/Traumeel