Differential Diagnosis for Shoulder Pain

The patient presents with shoulder pain that started after initiating an intense workout regimen, with symptoms evolving over time to predominantly affect the left shoulder. The pain is exacerbated by specific movements and interferes with sleep. Based on the history and physical examination, the following differential diagnoses are considered:

• Single Most Likely Diagnosis

  • Subacromial Impingement Syndrome: This condition is likely given the patient's history of intense workout regimen, particularly with exercises like push-ups and weighted dips that can cause repetitive strain on the shoulder. The pain localization to the anterior shoulder over the deltoid junction and the positive "praying" test support this diagnosis. The symptoms are also consistent with impingement of the rotator cuff tendons under the acromion.

• Other Likely Diagnoses

  • Rotator Cuff Tendinopathy: Given the patient's age and the nature of the pain, which is described as muscular or tendinous, rotator cuff tendinopathy is a plausible diagnosis. The pain pattern and exacerbation with specific movements are consistent with this condition.
  • Bicipital Tendinopathy: The anterior shoulder pain and the positive "praying" test could also suggest bicipital tendinopathy, especially if the long head of the biceps tendon is involved.
  • Scapulothoracic Dysfunction: The patient's initial symptoms of aching pain across both clavicles attributed to poor posture, and the current symptoms that include pain with reaching posteriorly, could indicate scapulothoracic dysfunction contributing to the shoulder pain.

• Do Not Miss Diagnoses

  • Thoracic Outlet Syndrome: Although less likely, thoracic outlet syndrome could present with shoulder pain and must be considered, especially given the patient's history of neck and back issues. However, the absence of tingling, numbness, or dizziness makes this less probable.
  • Referred Pain from Cervical Spine: Referred pain from the cervical spine, potentially due to a herniated disc or cervical spondylosis, is a critical diagnosis not to miss. The patient's past back issues and current symptoms could be consistent with this, although the lack of neck pain, tingling, or numbness makes it less likely.
  • Polymyalgia Rheumatica: This condition, characterized by aching and stiffness in the shoulder girdle, could be considered, especially in older adults. However, the patient's age, the absence of systemic symptoms like fever or weight loss, and the specific nature of the pain make this less probable.

• Rare Diagnoses

  • Adhesive Capsulitis (Frozen Shoulder): Although the patient's pain and stiffness could suggest adhesive capsulitis, the absence of significant restriction in range of motion and the specific exacerbating factors make this less likely.
  • Neer's Lesion (Terminology for a specific type of rotator cuff injury): A specific type of rotator cuff injury could be considered but is less common and would typically present with more acute trauma or a distinct incident of injury.
  • Osteonecrosis of the Humeral Head: This is a rare condition that could cause shoulder pain but would typically be associated with more systemic symptoms or risk factors such as long-term steroid use, and the patient does not have a clear history suggestive of this condition.