# Clinical Cases: Upper Limb - Shoulder Region

## Case 1: Rotator Cuff Tear

### Clinical Image
![Rotator Cuff Tear MRI](case_01_image.jpg)
*Source: [Wikimedia Commons - Rotator Cuff Tear MRI](https://commons.wikimedia.org/wiki/File:Rotator_cuff_tear_MRI.jpg) - CC BY-SA 3.0*

### Case Presentation
A 58-year-old house painter presents with 4 months of progressive right shoulder pain and weakness. He initially noticed pain when reaching overhead while painting ceilings, which has now progressed to difficulty lifting his arm to wash his hair. He reports night pain that disrupts sleep, particularly when lying on the affected side. He denies any acute injury or trauma. Physical examination reveals atrophy of the supraspinatus and infraspinatus fossae. Active range of motion is limited with painful arc between 60-120 degrees of abduction. Passive range of motion is full but painful. He has weakness with resisted external rotation and abduction. Empty can test (Jobe test) is positive with weakness and pain. Drop arm test is positive - he cannot slowly lower his arm from 90 degrees of abduction. Neer and Hawkins impingement signs are positive. Radiographs show superior migration of the humeral head with decreased acromiohumeral distance. MRI confirms a full-thickness tear of the supraspinatus tendon with retraction to the level of the glenoid, as well as partial thickness infraspinatus tear and moderate fatty infiltration of the supraspinatus muscle. Given the chronic tear with muscle atrophy, he undergoes arthroscopic rotator cuff repair with subacromial decompression.

### Key Learning Points
- The rotator cuff consists of four muscles: supraspinatus, infraspinatus, teres minor, and subscapularis (SITS)
- Supraspinatus initiates abduction (first 15 degrees) and passes through the narrow subacromial space
- The supraspinatus tendon has a watershed zone of relative hypovascularity predisposing to degeneration
- Full-thickness tears cause weakness and positive drop arm test; partial tears may have pain without weakness
- Fatty infiltration of muscle and tendon retraction indicate chronicity and affect surgical outcomes

---

## Case 2: Clavicle Fracture

### Clinical Image
![Clavicle Fracture](case_02_image.jpg)
*Source: [Wikimedia Commons - Clavicle Fracture X-ray](https://commons.wikimedia.org/wiki/File:Clavicle_fracture_X-ray.jpg) - CC BY-SA 3.0*

### Case Presentation
A 19-year-old cyclist is brought to the emergency department after a crash during a race. He went over his handlebars and landed directly on his left shoulder. He reports immediate pain over his left clavicle and is holding his left arm against his body for support. Physical examination reveals obvious deformity over the middle third of the left clavicle with visible tenting of the skin. There is significant swelling, tenderness, and palpable crepitus at the fracture site. The distal fragment is displaced inferiorly and medially due to the weight of the arm, while the proximal fragment is elevated by the sternocleidomastoid. Neurovascular examination of the left upper extremity is intact with normal radial pulse, sensation, and motor function. Chest examination is clear, and there is no subcutaneous emphysema. Radiographs confirm a displaced, comminuted fracture of the middle third of the clavicle with shortening greater than 2 cm. Given the significant displacement, comminution, and shortening (risk factors for nonunion), he undergoes open reduction and internal fixation with a superior clavicle plate. At 3-month follow-up, the fracture has healed with full return to cycling.

### Key Learning Points
- The clavicle is the most commonly fractured bone in the body; 80% occur in the middle third
- Middle third is the weakest point, lacking ligamentous attachments and having a transition in cross-section
- The sternocleidomastoid elevates the proximal fragment; arm weight pulls the distal fragment inferiorly and medially
- The subclavian vessels and brachial plexus lie posterior to the middle third clavicle and can be injured
- Operative indications include significant displacement, shortening >2cm, open fracture, and neurovascular injury

---

## Case 3: Acromioclavicular Joint Separation

### Clinical Image
![AC Joint Separation](case_03_image.jpg)
*Source: [Wikimedia Commons - AC Joint Separation](https://commons.wikimedia.org/wiki/File:AC_separation.jpg) - CC BY-SA 3.0*

### Case Presentation
A 32-year-old hockey player presents to the emergency department after being checked into the boards and landing directly on his right shoulder with his arm at his side. He reports immediate pain at the top of his shoulder. Physical examination reveals localized swelling and tenderness directly over the right acromioclavicular (AC) joint. There is a visible step-off deformity with the distal clavicle sitting higher than the acromion ("piano key" sign). Cross-body adduction elicits pain at the AC joint. Shoulder range of motion is limited by pain but neurovascular examination is intact. Weighted radiographs (holding 10 lb weights) demonstrate complete AC joint dislocation with the clavicle displaced superiorly by 100-300% of normal AC joint width, but the coracoclavicular (CC) distance is less than 100% increased compared to the opposite side. This is classified as a Rockwood Type III injury. The patient is given the option of nonoperative treatment with sling and physical therapy versus surgical reconstruction. He elects for initial conservative management. At 8-week follow-up, he has returned to full hockey participation with mild residual cosmetic deformity but full function.

### Key Learning Points
- The AC joint is stabilized by the AC ligaments (horizontal stability) and coracoclavicular ligaments (vertical stability)
- The coracoclavicular ligaments (conoid and trapezoid) prevent superior migration of the distal clavicle
- Rockwood classification: Type I (sprain), II (AC ligament tear), III (AC + CC ligament tear), IV-VI (severe displacement)
- Direct trauma to the point of the shoulder is the typical mechanism
- Type III injuries remain controversial; many athletes return to sport with conservative treatment