Anatomic location of the first dorsal extensor compartment for surgical De-Quervain's tenosynovitis release: A cadaveric study

Abstract

Background: De-Quervain's tenosynovitis is a disorder arising from the compression and irritation of the first dorsal extensor compartment of the wrist. Patients who fail conservative treatment modalities are candidates for surgical release. However, risks with surgery include damage to the superficial radial nerve and an incomplete release due to inadequate dissection. Currently, there is a paucity of literature demonstrating the exact anatomic location of the first dorsal extensor compartment in reference to surface anatomy. Thus, this cadaveric study was performed to determine the exact location of the first extensor compartment and to devise a reliable surgical incision to prevent complications.

Aim: To describe the location of the first dorsal compartment in relation to bony surface landmarks to create replicable surgical incisions.

Methods: Six cadaveric forearms, including four left and two right forearm specimens were dissected. Dissections were performed by a single fellowship trained upper extremity orthopaedic surgeon. Distance of the first dorsal compartment from landmarks such as Lister's tubercle, the wrist crease, and the radial styloid were calculated. Other variables studied included the presence of the superficial radial nerve overlying the first dorsal compartment, additional compartment sub-sheaths, number of abductor pollicis longus (APL) tendon slips, and the presence of a pseudo-retinaculum.

Results: Distance from the radial most aspect of the wrist crease to the extensor retinaculum was 5.14 mm ± 0.80 mm. The distance from Lister's tubercle to the distal aspect of the extensor retinaculum was 13.37 mm ± 2.94 mm. Lister's tubercle to the start of the first dorsal compartment was 18.43 mm ± 2.01 mm. The radial styloid to the initial aspect of the extensor retinaculum measured 2.98 mm ± 0.99 mm. The retinaculum length longitudinally on average was 26.82 mm ± 3.34 mm. Four cadaveric forearms had separate extensor pollicis brevis compartments. The average number of APL tendon slips was three. A pseudo-retinaculum was present in four cadavers. Two cadavers had a superficial radial nerve that crossed over the first dorsal compartment and retinaculum proximally (7.03 mm and 13.36 mm).

Conclusion: An incision that measures 3 mm proximal from the radial styloid, 2 cm radial from Lister's tubercle, and 5 mm proximal from the radial wrist crease will safely place surgeons at the first dorsal compartment.

Keywords: Cadaveric study; De-Quervain’s tenosynovitis; First extensor compartment; Lister’s tubercle; Radial styloid; Superficial radial nerve.

Figure 1

Histogram demonstrating superficial landmark data points for six cadaveric specimens. Each data bar demonstrates the value obtained for the cadaveric forearm specified in the legend provided. Notably, all variables do not demonstrate a significant outlier and maintain a close distribution of variables independent of laterality, age, and sex of the specimen. This demonstrates that the radial styloid, wrist crease, and Lister’s tubercle are all reliable markers to use to determine the location of the first dorsal compartment.

Figure 2

Cadaveric dissection. A: Initial cadaveric dissection of the first dorsal compartment. Right forearm cadaver model with a longitudinal incision centered over the first dorsal extensor compartment. Superficial dissection through the subcutaneous fat was performed with a scalpel blade and Metzenbaum scissors. Deep dissection and retraction of the soft tissues demonstrates the underlying musculature and extensor retinaculum as shown by the black arrow; B: Full length view of the extensor retinaculum. Cadaveric dissection demonstrating the full extent of the extensor retinaculum. Caliper measurements were performed as demonstrated in this graphic. The average length of the extensor retinaculum from its proximal to its distal length was 26.82 mm ± 3.34 mm; C: Deep dissection of the radial styloid and extensor retinaculum. Dissection demonstrating the most distal aspect of the radial styloid to the most distal aspect of the extensor retinaculum. An 18-gauge needle is used to mark the radial styloid process. The length from the radial styloid to the initial aspect of the extensor retinaculum measured 2.98 mm ± 0.99 mm; D: Anatomic relationship shown between Lister’s tubercle to the first dorsal extensor compartment. Lister’s tubercle is seen marked by the most distal aspect of the caliper, while the first extensor compartment shown by the proximal caliper marker. The distance from Lister’s tubercle to the proximal aspect of the retinaculum measured 13.37 mm ± 2.94 mm while distance from Lister’s tubercle to the start of the first dorsal compartment was 18.43 mm ± 2.01 mm; E: Multiple abductor pollicis longus (APL) tendon slips and sub-sheaths. Deep dissection into the first extensor compartment demonstrates multiple tendon slips of the APL tendon as shown by the black arrow. Four separate tendon slips are shown by the arrow, ultimately resulting in incomplete compartment release if not thoroughly dissected. The average number of APL tendon slips was three. A pseudo-retinaculum was also present in four out of six cadavers.