Rupture of the Fibro-Osseous Septum of the Second Extensor Compartment as the Cause of True Dorsal Trigger Wrist: Case Report

Abstract

This article presents a case of a dorsal trigger wrist, which was brought on by a rupture of the fibro-osseous septum of the second extensor compartment. This situation is highly uncommon and has not been previously documented. The septum, which divides the extensor carpi radialis brevis and the extensor carpi radialis longus on the second extensor compartment, is present in almost 45% of the population. The patient underwent surgical reconstruction of the septum, and a complete resolution of symptoms was achieved.

Introduction

A true trigger wrist is an uncommon pathology characterized by triggering, clicking, or snapping around the wrist. ¹ The term “true trigger wrist” implies that the origin is precipitated only by wrist movements.^{2 -4} Several potential causes have been identified, including pathology of the flexor and extensor tendons, carpal bones, and adjacent soft tissues. ⁵ However, there are few reports where the pathology affecting the second extensor compartment is responsible for the development of this syndrome.^{2,6 -8}

Compared to previously reported cases, this case is unusual, as no previous reports have shown that the rupture of the fibro-osseous septum of the second extensor compartment was the cause for the development of a trigger wrist.

Case Report

A 39-year-old right-handed male professional guitar player presented with a dorsal trigger wrist at the level of the second extensor compartment of the dominant hand. One month before the presentation, the patient had a bicycle accident with an outstretched hand. At that time, the patient reported pain in both the wrist and ipsilateral elbow. According to imaging results, radiographs were normal, while bone marrow edema was observed in the radial head and scaphoid on magnetic resonance imaging (MRI). Pain at the level of the scaphoid and elbow was resolved with a wrist splint for 1 month and progressive mobilization of the elbow, respectively. Subsequently, the patient noticed dorsal triggering with wrist flexion and extension. He denied any symptoms prior to the trauma. Active wrist movement was associated with a blockade sensation, and the physical examination revealed that there was visible painless dorsal triggering over the second extensor compartment. However, this effect was not observed on the contralateral side.

Dynamic ultrasound evaluation showed that the extensor carpi radialis longus (ECRL) tendon was mounted over the extensor carpi radialis brevis (ECRB) tendon during movement (Figure 1) (supplemental video 1).

Figure 1.

Dynamic ultrasound showing the mounting of the ECRL over the ECRB during wrist movement from flexion to extension.

Note. (a) The ECRL and ECRB remain separated when the wrist is flexed or neutral. (b) With an increase in wrist extension, the ECRL starts to move over the ECRB. (c) Finally, the ECRL was mounted on the ECRB, with the wrist fully extended. ECRL = extensor carpis radialis longus; ECRB = extensor carpis radialis brevis; EPL = extensor pollicis longus.

Surgery was performed using the wide-awake, local anesthesia, no tourniquet (WALANT) technique to allow conscious mobilization of the patient. A dorsal approach was performed over Lister’s tubercle. The indemnity of the extensor pollicis longus (EPL), ECRL, and ECRB was confirmed. The patient was asked to reproduce a trigger that corroborated ECRL tendon mounting over the ECRB (Figure 2). Initially, tenodesis was performed between the tendons of the second compartment, which was unsatisfactory, and the trigger wrist persisted. The suture stitches for tenodesis were removed, and a suture from the extensor retinaculum to the periosteum was performed with a size 2-0 nonresorbable polyester suture (Ti-cron, Covidien, MN, USA) to reconstruct the septum dividing both tendons. Subsequently, the instability resolved without further triggering (Figure 3). Wound washing and closure of wound planes were performed. The patient was in a long-arm cast for 6 weeks after surgery. A progressive mobilization plan was implemented to recover the wrist movement. Upon 6 months of follow-up, the range of motion against the opposing side was as follows: 70°/78° for flexion, 70°/80° for extension, 80°/80° for pronation, 90°/90° for supination, 12°/14° for radial deviation, and 50°/50° for ulnar deviation. The Quick Disabilities of the Arm, Shoulder, and Hand questionnaire (Q-DASH) was 13.6, and the total Patient-Rated Wrist Evaluation questionnaire was 5.5, 4 points on the pain subscale, and 1.5 points on the function subscale. Dynamic ultrasound showed that both tendons moved freely without the ECRL riding on the ECRB (supplemental video 2). The patient returned to his previous activities without wrist triggering or limitation.

Figure 2.

Intraoperative trigger wrist before treatment.

Note. The trigger effect can be observed as the wrist goes from slightly flexed (a) to extension (b and c). The ECRL and ECRB are separated in flexion or neutral (a), and the ECRL mounts over the ECRB during wrist extension. ECRL = extensor carpi radialis longus; ECRB = extensor carpi radialis brevis.

Figure 3.

After the septum reconstruction (yellow circle), both the ECRL and ECRB remain separated during motion from flexion (a) to full extension (b and c).

Note. ECRL = extensor carpi radialis longus; ECRB = extensor carpi radialis brevis.

Discussion

A true trigger wrist due to the pathology of the second extensor compartment is rare. Four cases have been described. The first case was reported by Lemon and Engber, ⁶ in which the patient had a nodule in the ECRL tendon as it entered the second extensor compartment of the wrist. Reduction tenoplasty of the nodule and release of the second dorsal compartment relieved all symptoms.

The second case was described by Koob and Steffens. ⁷ They reported the case of a 23-year-old patient, a professional tennis player, with a “synovial mass” around the ECRB, ECRL, and EPL.

In 2010, Yamazaki et al ⁸ also reported a case of a 23-year-old who suffered an ECRL rupture at the musculotendinous junction in the middle forearm while playing tennis. One month later, the patient developed a true trigger wrist due to synovitis of the ECRL tendon. The patient underwent surgery, and a mass 2 cm in diameter was found in the second dorsal compartment connected to the enlarged ECRL tendon. The patient’s symptoms were relieved after the mass and the remnants of the enlarged ECRL tendon were resected. The last case was reported by Luenam et al. ² They described a partial rupture of the ECRB, where the partial tendon rupture was bunching and formed a nodule.

All of the cases described above shared a common characteristic: the presence of a nodule or occupying mass that caused the trigger on the dorsal aspect of the wrist. The treatment for this condition was directly related to addressing this nodule or mass. In contrast, our patient had an intact tendon without any nodules or masses. The anatomy of the second extensor compartment has not been as extensively detailed. However, Schmidt and Lahl ⁹ described the presence of a slender fibro-osseous septum in almost 45% of the population. This septum guides the ECRB and ECRL into separate channels. Zancolli and Cozzi ¹⁰ and Zbrodowski et al ¹¹ also described this septum between both tendons (Figure 4).

Figure 4.

Axial view of the anatomical dissection of the wrist. (a) The second extensor compartment and its tendons are marked; the yellow arrow indicates the septum that divides them. (b) Enlarged images of the second compartment of the wrist.

Note. ECRL = extensor carpi radialis longus; ECRB = extensor carpi radialis brevis.

In this case, we consider a rupture of the septum of the second extensor compartment as the origin of the trigger wrist. This disruption allowed the ECRL to be mounted on the ECRB, thus altering the normal functioning of the tendons. Although we cannot confirm this assumption, the trigger effect was resolved only after reconstructing this septum. This highlights one of the benefits of using the WALANT technique: the possibility of intraoperative evaluation with active patient participation. ¹² Finally, the resolution of the pathology was also demonstrated on the postoperative dynamic ultrasound.

Conclusion

The development of a trigger wrist is atypical, with multiple causes for its development. In addition to the already-known causes, we must add the injury of the fibro-osseous septum in the second extensor compartment as another probable cause. We recommend using dynamic ultrasound for preoperative assessment and the WALANT technique for surgery, as it allows for intraoperative evaluation and performs modifications if necessary.