• The clavicle plays a crucial role in supporting and mobilizing the upper extremity, connecting it to the trunk and protecting subclavian vessels and the brachial plexus.
• Intra-articular disk between the clavicle and acromion helps correct bony incongruities but can degenerate over time.
• Injuries and arthritis are common causes of AC joint (ACJ) pain, with arthritis often resulting from constant stress on the joint, particularly in those who perform repeated overhead lifting activities.

• Important to rule out clavicular fractures or severe AC joint separation during screening.
• AC joint separations graded based on the Rockwood classification (I-VI), with grades I-III managed conservatively and grades IV-VI managed surgically.

• AC arthritis presents with progressively worsening shoulder pain, exacerbated by minor trauma or strenuous activity.
• Pain typically located anteriorly over the shoulder or referred to the shoulder and upper arm, worsened by overhead activities, weight lifting, and cross-body movements.
• Night pain, popping, clicking, grinding, and catching sensation with shoulder movement are common; careful history of trauma or injuries important for diagnosis.

• Painful arc from 170°-180° of flexion/abduction
• Orthopedic tests: Paxino sign, AC Shear Test, AC Resisted Extension Test, AC Joint Line Tenderness
• Higher validity to combine tests in cluster of which 2 are described in the literature

• Nonoperative management is first-line, including rest, activity modification, NSAIDs, corticosteroid injections, and physical therapy.
• Activity modification essential to prevent symptom re-aggravation; physical therapy aims to improve strength and range of motion.
• No clear evidence on effectiveness of steroid injections; surgery considered for severe ongoing symptoms unresponsive to conservative therapy, with arthroscopic surgery becoming more common.

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