Can a direct electrical shock of 120 AC volts to the arm or shoulder of an adult with possible occupational exposure cause tendinopathy that is amenable to treatment with a shoulder bursa steroid injection, such as triamcinolone acetonide?

Electrical Shock and Shoulder Tendinopathy: Injection Considerations

A 120 AC volt electrical shock to the arm/shoulder does not cause the typical overuse tendinopathy that responds to corticosteroid injections; however, if true tendinopathy or bursitis develops secondarily from the injury, subacromial bursa steroid injection may provide short-term pain relief but should be approached with significant caution given the lack of evidence for corticosteroids in non-overuse tendon pathology.

Understanding the Mechanism of Injury

Electrical injuries cause tissue damage through different mechanisms than mechanical overuse:

• Rotator cuff tendinopathy typically results from repetitive mechanical impingement of the coracoacromial arch onto the supraspinatus tendon, combined with hypovascularity in the region proximal to the tendon insertion 1
• Electrical shock injuries cause thermal damage, muscle tetany, and direct cellular injury—fundamentally different pathophysiology than the degenerative changes seen in classic tendinopathy 1
• The provided evidence addresses overuse tendinopathies in athletes and laborers with repetitive overhead work, not acute electrical trauma 1

Clinical Assessment Requirements

Before considering injection therapy, specific diagnostic criteria must be met:

• Perform Hawkins' test (92% sensitive for impingement) with forcible internal rotation at 90 degrees forward flexion 1
• Perform Neer's test (88% sensitive) eliciting pain with full forward flexion between 70-120 degrees 1
• Obtain MRI or ultrasound imaging to confirm true tendinopathy or bursitis rather than electrical injury sequelae 1, 2
• Look for specific findings: tendon signal abnormalities, bursal fluid, or impingement rather than acute trauma patterns 1

Corticosteroid Injection Considerations

If imaging confirms subacromial bursitis or secondary tendinopathy, injection may be considered with important caveats:

Injection Technique

• Use ultrasound guidance for accurate peritendinous (not intratendinous) injection to avoid tendon weakening 2, 3
• Inject into the subacromial-subdeltoid bursa, not directly into tendon substance 2, 3
• Consider high-volume injection (1 mL triamcinolone acetonide 40mg with 9 mL anesthetic) which provides superior early pain recovery compared to low-volume (2.837 times higher chance of complete recovery at 1 year) 4

Corticosteroid Selection

• Triamcinolone acetonide appears superior to methylprednisolone acetate for shoulder bursa injections, with 5 times higher chance of reaching complete functional recovery (Constant Score = 100) at 180 days 5
• The American Academy of Family Physicians notes no definitive recommendation exists for optimal corticosteroid selection, but triamcinolone acetonide has the strongest evidence for shoulder injections 2, 5

Critical Safety Warnings

Corticosteroid injections carry significant risks that are particularly relevant in non-typical tendinopathy:

• Corticosteroids may inhibit healing and reduce tensile strength, predisposing to spontaneous rupture 1, 2
• The role of inflammation in tendinopathies is unclear, making the theoretical basis for corticosteroid use questionable 1, 2
• Injections provide short-term pain relief but do not alter long-term outcomes 1, 2
• If re-injection is needed, wait at least 3 weeks as intervals shorter than 21 days cause irreversible cellular damage and prevent recovery of cell viability 6
• Doses above 0.1 mg/mL (equivalent to 40mg total) cause irreversible damage to rotator cuff-derived cells 6

Alternative Treatment Approach

Given the atypical etiology (electrical injury rather than overuse), conservative management should be prioritized:

• NSAIDs for acute pain management (topical formulations eliminate GI hemorrhage risk) 1
• Ice application through wet towel for 10-minute periods 1
• Physical therapy focusing on proper biomechanics once acute injury resolves 1
• If conservative treatment fails after several months, consider imaging-guided injection or surgical evaluation 1, 2

Key Clinical Pitfall

The fundamental issue is that electrical shock does not cause the degenerative tendinopathy described in the available evidence. The guidelines address repetitive overuse injuries in athletes and overhead laborers 1. Applying these treatment paradigms to electrical injury assumes similar pathophysiology, which is unsubstantiated. If shoulder pain persists after electrical injury, thorough imaging is essential to identify the actual pathology (acute trauma, nerve injury, muscle damage) rather than assuming classic tendinopathy amenable to steroid injection 1.