Clinical History
Pain over the dorsal ulnar aspect of right wrist. Chronic discomfort due to work with a pneumatic drill for years. A plain radiograph of wrist, taken months ago, was negative for pathologic findings. On clinical examination a minor swelling and pain over the distal ulna was evident on ulnar deviation.
Imaging Findings
The patient presented with pain over the dorsal ulnar aspect of his right wrist. He complained of chronic discomfort due to work with a pneumatic drill for years. A plain radiograph of his wrist, taken months ago, was negative for pathologic findings. On clinical examination a minor swelling and pain over the distal ulna was evident on ulnar deviation.
An MRI of the right wrist was performed, with spin echo T1-weighted and turbo spin echo T2-weighted fat-suppressed sequences in the coronal plane and a 3D FFE T2-weighted sequence in the axial plane. This showed presence of fluid within the extensor carpi ulnaris (ECU) tendon sheath. The tendon was mildly thickened with abnormally increased signal within it (Figs 1-3).
A diagnosis of ECU tenosynovitis was made. Conservative treatment was instituted by means of cortisone injection and temporary immobilization.
Discussion
The sixth dorsal compartment is the second most common site of tenosynovitis following de Quervain’s disease [1-4]. The extensor carpi ulnaris provides stability to the distal radioulnar joint by its dorsal position and the overlying extensor retinaculum [3-5]. An ECU tenosynovitis occurs in sports such as rowing and racquet sports, requiring a snapping wrist (e.g. squash, badminton) and presents with chronic pain along the ulna border of the wrist.
This is a primary tenosynovitis (without an underlying condition). The MRI appearance of this entity demonstrates fluid surrounding the tendon on T2-weighted images. Thickening of the surrounding sheath is best seen on T2-weighted images and on fast spin-echo fat suppressed Proton Density weighted images. Increased signal within the tendon consistent with tendinosis may be observed on Proton Density or T1-weighted images. Focal calcifications seen in some chronic cases may be detected as a signal void on MRI along the tendon sheath [4]. Treatment is conservative in the early stages with temporary immobilization and cortisone injection into the fibro-osseous tunnel. Progression of the condition to fibrosis of the sixth dorsal compartment may require surgical intervention [1, 3]. However such intervention may be complicated by subsequent recurrent ulnar subluxation of the ECU. This may be observed on an MRI done after surgery [4].
If the tenosynovitis is secondary (related to overuse relative to underlying wrist instability), then dorsal-medial subluxation of the ECU tendon with rupture of the overlying part of the extensor retinaculum occurs from a sudden supination, ulnar deviation and volar flexion force [3,4]. This has been reported in tennis players as well as golfers, weightlifters and even bareback broncho riders. In this condition the ECU tendon can recurrently sublux. This is characterized by a painful snap over the dorso-ulna area of the wrist with supination and ulna deviation [2,4]. This recurrent subluxation of the ECU tendon leads to chronic progressive pain and tendon thickening. In the acute stage treatment consists of immobilization for 6 weeks in a long arm cast in supination and radial deviation. For chronic cases immobilization is ineffective, and surgical restabilisation of the ECU tendon is required [1-3].
Differential Diagnosis List
Extensor Carpi Ulnaris tenosynovitis
Final Diagnosis
Extensor Carpi Ulnaris tenosynovitis
