Case Study: AC Joint Separation in a Competitive Cyclist

Patient Profile:
Sarah, a 28-year-old competitive cyclist, presents to the clinic after falling off her bike during a race two days ago. She landed directly on her right shoulder when she fell. Since the incident, she has been experiencing significant pain at the top of her shoulder, especially when trying to lift her arm above shoulder height or across her body. She also reports visible swelling and a "bump" at the top of her shoulder. Sarah is anxious about the upcoming cycling competition in four weeks and is concerned about how long her recovery will take.

She tried icing her shoulder and taking over-the-counter ibuprofen, but the pain persists, particularly with movements requiring shoulder flexion or adduction. She denies any numbness, tingling, or weakness in her arm or hand.

Physical Exam Findings:

• Inspection: Visible swelling and mild deformity over the acromioclavicular (AC) joint. A noticeable "step-off" deformity is present at the AC joint.
• Palpation: Significant tenderness over the AC joint and clavicle. No tenderness over the scapula or glenohumeral joint.
• Range of Motion (ROM): Limited active ROM due to pain, particularly with abduction and flexion above 90 degrees. Pain with shoulder adduction across the chest (horizontal adduction).
• Strength: Strength is 5/5 in all planes, but testing is limited by pain during shoulder flexion and abduction.
• Special Tests:
  • Cross-Body Adduction Test: Positive (pain over the AC joint)
  • O'Brien’s Test: Positive (pain over the AC joint)
  • Paxinos Sign: Positive
  • AC Shear Test: Positive
  • Apprehension Test: Negative
  • Neer and Hawkins-Kennedy Tests: Negative

Imaging:
X-ray shows elevation of the distal clavicle relative to the acromion, consistent with an AC joint separation. No fractures are noted.

Questions for Case Assessment:

Using this information, please answer these questions:

1. What is the likely diagnosis for Sarah’s shoulder injury based on her mechanism of injury, physical exam findings, and imaging results? How would you classify this injury based on the severity?
   Provide a diagnosis and use the Rockwood classification system to describe the severity of Sarah's AC joint separation.
    
2. Explain the significance of the positive Cross-Body Adduction Test, O'Brien’s Test, and AC Shear Test. What specific pathology do these tests assess, and how do they support the diagnosis of AC joint separation?
   Discuss what each test evaluates and why they are relevant in confirming an AC joint injury.
    
3. What are the primary treatment options for Sarah’s AC joint separation? How would you approach her treatment plan, considering her competitive cycling schedule and the severity of her injury?
   Outline both non-surgical and surgical treatment options based on the Rockwood classification, including pain management, physical therapy, and return-to-sport considerations.
    
4. What factors would influence whether Sarah’s AC joint separation requires surgical intervention? At what point would you consider referring her to an orthopedic surgeon, and what surgical options might be discussed?
   Provide guidance on when to refer for surgery and what type of surgical repair (e.g., Weaver-Dunn procedure, distal clavicle resection) may be indicated for more severe cases.