1 Introduction

The acute extensor carpi ulnaris (ECU) tenosynovitis presents with pain at the dorsal ulnar aspect of the wrist, particularly during wrist supination, wrist flexion, and ulnar deviation. The most common causes are overuse syndromes (athletes) and inflammatory pathologies (rheumatoid arthritis). It is mandatory to exclude coexistent pathologies such as triangular fibrocartilage complex, lunotriquetral ligament, distal radioulnar joint, or ulnar styloid injuries. The ECU synergy test, ultrasound, and MRI confirm the diagnosis^1–3. Most patients are managed nonoperative with splints, rest, lifestyle and sports activity modifications, pain medications, and rarely steroid injections^1–4. There are situations where patients have persistent or chronic tenosynovitis with positive clinical features and diagnostic findings. The treatment of such symptomatic chronic tenosynovitis is challenging.

ECU tenosynovitis associated with tendon subluxation/dislocation or tendon tears/rupture benefits from the surgical reconstruction of the sub sheath with or without tendon grafting^1,2. The functional outcome is good in ECU tenosynovitis associated with tendinous pathologies⁵. But the cases requiring surgical treatment for ECU tenosynovitis with minimal sub-sheath involvement must be promptly recognized because they may result in chronic discomfort or permanent disability⁶. However, we recommend reconstructing a new sub-sheath using an extensor retinaculum flap and ECU dorsal transposition for chronic tenosynovitis.

1.6

1.6 Illustrative case

A 34-year-old woman was reported to the hand surgery department with severe right-side ulnar wrist pain for 12 months. She had failed steroid injections, splints, and pain medications. Tenderness over the ECU tendon (dorsal ulnar wrist) and a positive ECU-synergy test confirmed tenosynovitis. There was no bowstring of the tendon (subluxation). Wrist radiographs were normal. The ultrasound and the MRI confirmed ECU tenosynovitis (Fig. 1) without instability or subluxation. Surgical exploration showed yellowish-discolored tissues in the subcutaneous plane due to multiple steroid injections. The extensor retinaculum over the sixth compartment was incised to expose the ECU tendon. Tenosynovectomy was performed, and the torn edges of the sub sheath were debrided. Sub-sheath reconstruction with the extensor retinaculum was done (Fig. 2), and the wrist was immobilized for 4 weeks. At 24 months follow-up; the wrist extension was 66°, flexion 65°, radial deviation 16°, ulnar deviation 32°, pronation 83°, and supination 84°. The patient improved after the surgery with a DASH of 5 and a patient-reported wrist evaluation (PRWE) of 20. The grip strength was 31 kg, and the patient returned to the previous work.

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Fig. 1 A- T2- MRI image shows thickened ECU tendon surrounded (red arrows) by high signal intensity consistent with fluid. B- T1-weighted MRI image displays the thickening of the ECU tendon. There is intermediate signal intensity surrounding the ECU tendon consistent with fluid and thickening of the tendon sheath (red arrows). C- Axial MRI image shows thickening of the ECU tendon at the level of the ulnar styloid and high signal intensity of the tendon sheath (red arrows). . (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)

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Fig. 2 The extensor retinaculum flap was passed under the ECU tendon, wrapped around it, and sutured to itself with non-absorbable sutures.

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2 Discussion

Chronic ECU tenosynovitis is rare. Patients usually present to the clinic with a long duration of chronic pain and tenderness in the dorsum of the ulnar aspect of the wrist and dysfunction. These patients have tried multiple nonoperative treatments and steroid injections with little benefits. Most of these patients cannot do their daily activities. Surgical release of the sixth extensor compartment, debridement, and synovectomy is the treatment of choice if conservative treatment fails. Hajj et al. reported that synovectomy and sixth compartment release completely relieved the symptoms of chronic tenosynovitis⁴. The authors released the ECU tendon osseous canal in their series and tightly repaired the extensor retinaculum to prevent ECU subluxation⁴. However, the tight repair may lead to tendon tightness, adhesions, stenosing tenosynovitis recurrence, and sometimes retinaculum rupture causing tendon subluxation. The surgical reconstruction must aim to debride and stabilize the ECU tendon during pronation and supination.

In our case, we performed synovectomy, sixth compartment release, ECU tendon dorsal transposition, and created a new sub-sheath using the ulnar-based retinaculum flap. The sub-sheath reconstruction allowed free movement of the ECU tendon and prevented adhesions and subluxation/dislocation. It is also mandatory to adjust the intraoperative retinacular flap suturing at ECU's maximum stress (wrist flexion, supination, and ulnar deviation) to prevent further complications.

Recommending dorsal transposition of the ECU tendon and a new sub-sheath reconstruction by an extensor retinaculum flap for all chronic ECU tenosynovitis based on this single case may not be accepted and is a limiting factor. Moreover, we need a more prospective study to design robust guidelines for this symptomatic and rare presentation of chronic ECU tenosynovitis with minimal sub-sheath pathologies.

3 Conclusion

The treatment of chronic tenosynovitis of the ECU depends on the patient's symptoms, age, functional requirements, and degree of tendon inflammation. Synovectomy, compartment release, and a new sub-sheath reconstruction stabilize the ECU and relieves the symptoms of chronic tenosynovitis. The ulnar-based extensor retinaculum flap and dorsal transposition of the ECU achieve good wrist movements and long-term functional outcomes in chronic tenosynovitis.

Author contribution

TJJ: Roles/writing – original draft, Data curation, Conceptualization.

SN and GRP: Writing – review & editing.

Registration of research studies

1.Name of the registry: Not applicable.2.Unique Identifying number or registration ID: Not applicable.3.Hyperlink to your specific registration (must be publicly accessible and will be checked): Not applicable.

Informed consent

Written informed consent was obtained from the patient(s) for their anonymized information to be published in this article.

Ethical approval

Ethical approval for this study was obtained from the Ethical Committed Board of OHRC Approved. No 05/2022.

Funding

None.

Provenance and peer review

Not commissioned, externally peer-reviewed.

Guarantor

J Terrence Jose Jerome.