Isolated Extensor Carpi Ulnaris Tenosynovitis

A 28-yr-old male patient presented with a 5-day history of ulnar-sided left wrist pain that began after a full/excess extension of the wrist and elbow due to falling backward. His past medical history was unremarkable. Physical examination revealed severe pain in the ulnometacarpal joint upon palpation. He experienced pain around the ulnar styloid process during radial deviation, and all three triangular fibrocartilage complex tests—known as the load test, press test, and gripping rotatory impaction test—were positive. Ultrasound (US) examination performed on the 4th day after the injury revealed hypoechoic thickening of the extensor retinaculum of the extensor carpi ulnaris (ECU) tendon and fluid within tendon sheath, consistent with tenosynovitis (Fig. 1). Sono-palpation was also positive. Magnetic resonance image revealed mild tendinosis of the ECU tendon with normal triangular fibrocartilage complex (Fig. 1). The patient was prescribed a resting splint, cold therapy, and nonsteroidal anti-inflammatory drug. He reported substantial symptom relief at his second-week follow-up.FIGURE 1: When compared with the normal side (A, C), longitudinal (B) and axial (D) ultrasound images demonstrate the significant fluid (asterisks) around the ECU tendon just above the triangular fibrocartilage complex. Magnetic resonance imaging (T2 sequence-axial view) shows the very mild tendinosis in the ECU tendon (arrow) at the ulnar styloid level (E). Tri, triquetrum; U, ulna.The ECU tendon is located in the 6th extensor compartment of the wrist and can be affected by trauma, inflammation, overuse, and certain medications.1 Although ECU tendinopathy is most commonly seen in sports-related injuries, it can, albeit rarely, occur after fall episodes.1 For sure, US can be used as a complementary/initial imaging/diagnostic modality for these cases and has numerous advantages including being handy, patient-friendly, and radiation-free. In addition, real-time/dynamic evaluation of musculoskeletal structures (e.g., tendon, triangular fibrocartilage complex, muscle, bone) can be conducted with US.2 Needless to say, US may reveal musculoskeletal soft tissue pathologies more accurately, and its findings might align more closely with the clinical presentation of patients than other imaging techniques like magnetic resonance imaging. For instance, in our patient, the clinical symptoms (visual analog scale score was eight before the treatment) were more compatible with the US findings than the magnetic resonance imaging findings, as the US findings were more consistent with a more severe clinical picture (significant fluid/tendinosis in the US examination compared with mild tendinosis findings on magnetic resonance imaging). Last but foremost, US also helped us to distinguish tendinitis from possible triangular fibrocartilage complex pathology, as it was the most likely diagnosis before the US imaging based on the patient’s physical examination and history.3