de Quervain's Disease: Detection of Intracompartmental Septum of the First Extensor Compartment on Ultrasound
de Quervain's disease is tenosynovitis of the tendons of the first extensor compartment of the wrist. An intracompartmental septum (subcompartmentalization) divides the compartment into separate recesses, which has clinical significance in cases of ineffective conservative treatment and treatment planning.
Anatomical Basis
Normally, the first extensor compartment contains the tendons of the abductor pollicis longus (APL) and extensor pollicis brevis (EPB). An intracompartmental septum forms a separate subcompartment — more commonly for the EPB tendon. Sex differences have been noted in the anatomy of the radial grooves of the first compartment (Gurses IA et al., Skeletal Radiol 2016).
Ultrasound Signs of the Septum
Examination is performed predominantly in the axial plane at the level of the radial styloid process. The septum is visualized as a thin hyperechoic line dividing the compartment into subcompartments; at its attachment site to the radius, an additional bony ridge (groove) on the cortical surface is often identified. According to Choi et al. (Radiology 2011), ultrasound detects the intracompartmental septum with 100% sensitivity and 96% specificity.
Clinical Significance
The septum reduces the efficacy of injection therapy: the glucocorticoid must reach the affected subcompartment, otherwise part of the tendon sheath remains inaccessible. The presence of a septum detected on ultrasound is associated with failure of ultrasound-guided injection (De Keating-Hart E et al., J Hand Surg Eur 2016). In surgical treatment, it is important to open the sheath of the affected subcompartment — otherwise the release may be ineffective. Therefore, preoperative ultrasound identification of subcompartmentalization helps plan both targeted injection and the extent of surgical intervention.
Frequently asked questions
What does the first extensor compartment normally contain?
The tendons of the abductor pollicis longus (APL) and extensor pollicis brevis (EPB).
How does an intracompartmental septum appear on ultrasound?
As a thin hyperechoic line dividing the compartment into subcompartments; at its attachment site to the radius, an additional bony ridge is often visible. According to Choi et al. (Radiology 2011), ultrasound detects it with 100% sensitivity and 96% specificity.
In which plane is the septum best visualized?
In the axial plane at the level of the radial styloid process.
Why is subcompartmentalization clinically important?
The presence of a septum is associated with failure of injection therapy (De Keating-Hart et al., 2016): the medication must reach the affected subcompartment, and during surgery, the sheath of that specific subcompartment must be opened.