What is the treatment for a patient with medial subluxation of the right extensor carpi ulnaris wrist, considering potential comorbidities such as rheumatoid arthritis?

Treatment of Medial Subluxation of the Extensor Carpi Ulnaris Tendon

For medial (volar) subluxation of the extensor carpi ulnaris (ECU) tendon, surgical reconstruction of the ECU subsheath is the definitive treatment, particularly when conservative management fails or in cases of recurrent subluxation. 1, 2

Initial Conservative Management

• Immobilization should be attempted first in acute cases (within 2-3 weeks of injury) using a short-arm cast or splint with the forearm in pronation for 4-6 weeks, as this position relocates the ECU tendon into its anatomic groove 1, 2
• Conservative treatment is less successful in chronic cases or when there is significant subsheath attenuation 1, 2

Surgical Indications

Proceed to surgery when:

• Conservative management fails after 6 weeks 1, 2
• Chronic subluxation is present (>3 months) 2
• Recurrent subluxation occurs with activities 1, 2
• Associated pathology is identified (TFCC tears, lunotriquetral ligament tears, ulnar styloid nonunion) 2

Surgical Technique

The standard surgical approach involves:

• Reconstruction of the ECU subsheath using extensor retinaculum when the subsheath is attenuated or torn 1, 2
• Advancement of the ECU sheath to periosteum using suture anchors for secure fixation 3
• Address any associated pathology identified intraoperatively, including TFCC tears (present in 39% of cases) or lunotriquetral ligament tears (present in 14% of cases) 2

Special Considerations in Rheumatoid Arthritis

If the patient has rheumatoid arthritis with ECU subluxation:

• Wrist arthrodesis becomes the treatment of choice when ECU subluxation is combined with carpal bone destruction and instability 4
• Modern plating techniques allow high primary stability without cast immobilization, which is particularly beneficial for multimorbid RA patients 4
• Splinting, orthoses, and/or compression are conditionally recommended for wrist involvement in RA patients as part of comprehensive management 5
• Refer to occupational therapy for proper fitting and guidance on orthotic use 5

Diagnostic Workup

Before proceeding with treatment:

• MRI without contrast is the ideal imaging modality to evaluate ECU tendon pathology, subsheath integrity, and associated soft tissue injuries (TFCC tears, ligament injuries) 6
• MRI will show increased T2 signal around the ECU tendon consistent with inflammation and can demonstrate the subluxation pattern 1
• Dynamic ultrasound can demonstrate ECU subluxation during supination and relocation during pronation 3

Expected Outcomes

• Surgical reconstruction typically prevents recurrent dislocation with good functional outcomes at 12-month follow-up 1
• Approximately 79% of patients (22 of 28) return to previous activities after surgical treatment 2
• Common pitfalls include: failure to identify associated ulnar-sided pathology (TFCC tears in 39%, lunotriquetral tears in 14%), anatomic variants (anomalous tendon slips in 25%, ulnar styloid nonunion in 14%), and inadequate subsheath reconstruction leading to recurrence 2

Rehabilitation

• Post-surgical immobilization in pronation for 4-6 weeks is standard 1, 2
• Joint protection techniques and hand therapy are conditionally recommended to optimize functional recovery 5
• Some patients may require tenolysis if adhesions develop (occurred in 7% of cases) 2