ECU Tendinitis: Initial Treatment Approach and the String Test
Understanding the "String Test" for ECU Tendinitis
The term "string test" appears to be a misinterpretation or colloquial reference to diagnostic provocative maneuvers for ECU tendinitis, most likely referring to the ECU synergy test or carpal supination test, which are the validated clinical examination techniques for this condition. 1, 2
Diagnostic Provocative Maneuvers
Most Sensitive Test: Carpal Supination Test
- The carpal supination test (both hand and forearm supination) is the most sensitive provocative maneuver for detecting ECU tendinitis, generating 27 times higher pressure in the ECU compartment compared to neutral position and 3 times higher than other tests. 2
- This test produces the highest extratendinous pressure and tendon strain in the sixth extensor compartment. 2
ECU Synergy Test
- The ECU synergy test differentiates between intra-articular and extra-articular pathology by utilizing the principle of muscle synergism. 1
- A positive synergy test with greater than 90% pain relief after ECU tendon sheath injection confirms isolated ECU tendinitis. 1
- This test helps minimize unnecessary MRI and diagnostic arthroscopy by distinguishing ECU tendinitis from ulnar-sided intra-articular pathology. 1
Initial Conservative Treatment (First 3-6 Months)
First-Line Interventions
Begin with relative rest, ice therapy, NSAIDs, and eccentric strengthening exercises for 3-6 months, as approximately 80% of patients with overuse tendinopathies fully recover with this approach. 3, 4
Relative rest means avoiding activities that provoke pain while maintaining some movement to prevent muscle atrophy and deconditioning. 4
Ice therapy provides short-term pain relief and reduces swelling in the acute phase. 4
NSAIDs (topical preferred): Topical NSAIDs are equally effective as oral formulations but eliminate the risk of gastrointestinal hemorrhage associated with systemic NSAIDs. 4, 5
- For patients with cardiovascular disease or risk factors, use a stepped-care approach starting with acetaminophen or aspirin at the lowest efficacious dose. 3
Eccentric strengthening exercises are the cornerstone of rehabilitation, stimulating collagen production and guiding proper alignment of newly formed collagen fibers. 4, 5
Activity Modification
- For athletes in stick and racquet sports (where ECU tendinopathy is common due to repetitive motion and axial loading), modify technique to minimize repetitive stresses on the tendon. 5
Second-Line Treatments (If Initial Management Fails)
Corticosteroid Injections
- Use corticosteroid injections with caution: They may provide more effective acute pain relief than oral NSAIDs but do not improve long-term outcomes. 4, 5
- Critical warning: Corticosteroids may inhibit healing, reduce tensile strength, and potentially predispose to tendon rupture; avoid direct injection into the tendon substance. 3, 4
Additional Modalities
- Therapeutic ultrasonography may decrease pain and increase collagen synthesis, though evidence is limited. 4
- Extracorporeal shock wave therapy (ESWT) appears safe and effective but requires further research. 4
- Splinting and manual therapy can be incorporated into the rehabilitation program. 5
Surgical Considerations (After 3-6 Months of Failed Conservative Treatment)
When to Consider Surgery
- Surgical evaluation is warranted if pain persists despite 3-6 months of well-managed conservative treatment. 4, 6
Surgical Approach
- Surgical techniques include excision of abnormal tendon tissue and longitudinal tenotomies to release scarring and fibrosis. 4
- Always perform diagnostic wrist arthroscopy during surgical planning: TFCC tears are identified in approximately 57% of patients with chronic ECU tendinopathy and should be treated concomitantly. 6
- Ultrasound-guided retinaculum release of the sixth dorsal compartment is a novel technique for chronic, recalcitrant cases. 7
Critical Pitfalls to Avoid
- Do not rush to surgery before completing an adequate 3-6 month trial of conservative therapy, as 80% of patients recover with conservative management alone. 3, 4
- Do not use corticosteroid injections as first-line treatment due to potential tendon weakening effects. 4
- Do not overlook concomitant TFCC pathology: If the patient has a positive ECU synergy test but also pain with lunotriquetral ballottement or TFCC compression, consider combined pathology requiring MRI or arthroscopy. 1, 6
- Avoid complete immobilization for prolonged periods as it leads to muscle atrophy and deconditioning. 4