A 34 year old male presenting to the emergency department for left shoulder pain. The pain is constant and worse with movement. He frequently has been feeling similar pain but was in a motor vehicle accident yesterday that exacerbated the pain. He was noted to have a left shoulder deformity with intact range of motion at the shoulder. What’s the diagnosis and treatment?
Answer: Grade III acromioclavicular joint separation; immobilize with a sling for 6-12 weeks and follow up with orthopedic surgery.
| Grade | Ligament involvement | X-ray Findings and Exam | Treatment |
| I | – AC ligament sprain – No instability of clavicle  | Exam: Tenderness over AC joint X-ray: Normal imaging | Ice, rest, analgesics, immobilization Early range of motion 1-2 weeks |
| II | – AC ligament rupture – Sprain of coracoclavicular ligament  | Exam: Tenderness and mild step off of AC joint X-ray: Clavicle elevated 25-50% above acromion, widening of the AC joint | Ice, rest, analgesics, immobilization Early range of motion 1-2 weeks |
| III | – AC ligament rupture – Coracoclavicular ligaments partially ruptured – Deltoid and trapezius muscles detached  | Exam: Shoulder droops, prominent distal clavicle X-ray: Clavicle elevated 100% above acromion, widening of coracoclavicular space | Conservative with sling immobilization Some cases may be operative |
| IV | – AC joint dislocation with AC ligament rupture – Complete or partial rupture of coracoclavicular ligament – Clavicle displaced posteriorly  | Exam: Posterior displacement of clavicle X-ray: Axillary radiograph required to see posterior dislocation | Surgical repair |
| V | – AC joint dislocation with AC ligament rupture – Complete rupture of coracoclavicular ligament  | Exam: Gross clavicular deformity X-ray: AC joint dislocated, coracoclavicular interspace with 200-300% disparity | Surgical repair |
| VI | – AC joint dislocation with AC ligament rupture – Intact coracoclavicular ligament – Clavicle displaced inferiorly – Intact, partial or complete deltoid and trapezius detachment  | Exam: Severe swelling X-ray: AC joint dislocated, clavicle displaced inferiorly | Surgical repair |
References:
Gorbaty JD, Hsu JE, Gee AO. Classifications in Brief: Rockwood Classification of Acromioclavicular Joint Separations. Clin Orthop Relat Res. 2017 Jan;475(1):283-287. doi: 10.1007/s11999-016-5079-6. Epub 2016 Sep 16. PMID: 27637619; PMCID: PMC5174051.
Tintinalli’s Emergency Medicine: A Comprehensive Study Guide, 9th Edition. Bjoerson, L. Ebinger, A. Chapter 271. Page 1824-1826. McGraw Hill Professional, 22 Oct. 2019.
