Why you feel pain on your shoulder
1. Acromioclavicular (AC) Joint Sprain and Dislocation
his injury typically occurs following a direct fall onto the shoulder or a fall onto an outstretched hand.
• Sprain: Partial elongation or incomplete tearing of the supporting ligamentous structures of the AC joint.
• Dislocation: Complete rupture of the acromioclavicular and coracoclavicular ligaments, resulting in superior displacement of the distal clavicle. This deformity is often visually apparent on physical inspection as a prominent “step-off” deformity.
2. Acromioclavicular Osteoarthritis
This condition arises from age-related degeneration or cumulative mechanical stress leading to progressive articular cartilage loss within the AC joint.
• Narrowing of the joint space results in direct osseous contact, producing pain with loading and motion.
• It is particularly prevalent among individuals engaged in heavy manual labor or overhead-intensive athletics over an extended period.
3. Distal Clavicle Osteolysis (Weightlifter’s Shoulder)
Repetitive high-load axial stress — most commonly from bench pressing and similar resistance exercises — leads to resorption and erosion of the distal clavicle.
• Colloquially referred to as “weightlifter’s shoulder,” this condition is characteristically observed in individuals engaged in frequent, heavy resistance training.
4. AC Joint Synovitis / Inflammatory Arthropathy
In the absence of discrete traumatic injury, repetitive mechanical stress from overhead activities or horizontal adduction of the upper extremity can precipitate intra-articular inflammation of the AC joint.
• Patients typically report pain with end-range shoulder elevation and cross-body adduction maneuvers.