Inability to Straighten Arm with Elbow Pain
The most likely causes of your inability to extend your arm with elbow pain include elbow dislocation (with or without fracture), severe ligamentous injury, or nerve entrapment syndrome—all of which require immediate plain radiographs to exclude fracture or dislocation before considering soft tissue pathology. 1
Immediate Diagnostic Approach
Obtain plain radiographs of the elbow first to exclude:
- Acute fracture or dislocation 1
- Joint effusion (suggesting occult fracture) 2
- Heterotopic ossification 2
- Loose bodies or osteochondral lesions 2
The inability to fully extend the elbow (loss of terminal extension) combined with pain is a red flag for significant structural injury that requires urgent imaging. 1
Most Likely Causes Based on Mechanism
Traumatic Causes (Fall or Direct Blow)
- Elbow dislocation with ligamentous injury: Results in acute fractures and/or dislocation with inability to extend due to joint instability 1
- Collateral ligament complex injury: Causes decreased range of motion and instability 1
- Capsular injury: Leads to pain and mechanical block to extension 1
Soft Tissue Injuries Without Obvious Trauma
- Severe lateral or medial epicondylitis: Causes pain with wrist extension against resistance, though typically doesn't prevent passive extension 3, 4
- Ulnar nerve entrapment: Presents with elbow pain, weakness, and tingling, potentially limiting extension due to pain 2, 5
- Radial tunnel syndrome: Can mimic lateral epicondylitis but may have associated weakness 2, 4
Inflammatory/Arthritic Causes
- Elbow arthritis: Causes debilitating pain and stiffness with loss of range of motion 6
- Olecranon bursitis: Presents with posterior swelling and pain, though typically doesn't prevent extension unless severe 2, 4
Critical Pitfalls to Avoid
Do not assume this is simple tendinitis if you cannot fully extend the elbow—the mechanical inability to straighten the arm suggests either:
- Joint dislocation or subluxation 1
- Severe ligamentous instability 1
- Large joint effusion from fracture 2
- Nerve injury causing weakness 2, 5
Static imaging may miss dynamic instability—if initial radiographs are normal but you still cannot extend the elbow, consider stress radiographs or dynamic ultrasound to evaluate ligamentous integrity. 1, 7
Next Steps if Radiographs Are Normal
If plain films show no fracture or dislocation but extension remains limited:
- Consider MRI without contrast to evaluate soft tissue pathology including ligament tears, tendon injuries, or joint effusion 2
- Dynamic ultrasound has 96% sensitivity for detecting nerve dislocation and soft tissue abnormalities that may be missed on static imaging 7
- MR arthrography at 3T is more accurate than standard MRI for collateral ligament injuries if ligamentous pathology is suspected 7
When to Seek Urgent Evaluation
You need immediate medical attention if you have:
- Visible deformity of the elbow 1
- Inability to move the elbow at all 1
- Numbness or tingling in the hand (suggesting nerve injury) 2, 5
- Severe swelling or discoloration 1
Conservative Management (Only After Excluding Serious Injury)
If imaging excludes fracture, dislocation, and severe ligamentous injury:
- Rest and activity modification to reduce mechanical irritation 7
- NSAIDs for pain control 7, 4
- Physical therapy focusing on range of motion and strengthening once acute pain subsides 7, 4
- Corticosteroid injection may be considered for persistent symptoms after 5-9 months of conservative therapy 7
The key distinction is whether this is a mechanical block (requiring urgent intervention) versus pain-limited motion (amenable to conservative treatment). 1, 4