De Quervain's Tenosynovitis on MRI & X-ray: Imaging Findings

Up to 30% of individuals have a fibrous or bony septum creating a separate subcompartment for the extensor pollicis brevis tendon within the first dorsal compartment. When a corticosteroid injection is placed into the main compartment containing the abductor pollicis longus, the EPB subcompartment may not be reached, explaining failure rates of approximately 30% when septation is present compared to less than 10% without septation. MRI or ultrasound can identify septation preoperatively, guiding whether a two-compartment injection technique or surgical release with deliberate opening of both subcompartments is required.

MRI directly visualizes the first dorsal compartment extensor retinaculum thickening, fluid surrounding the APL and EPB tendons, peritendinous and subcutaneous edema around the radial styloid, and tendon signal abnormality indicating tendinopathy. Importantly, MRI simultaneously evaluates the scaphoid for fracture or nonunion, the first CMC joint for osteoarthritis, the intersection zone at the second dorsal compartment crossing for intersection syndrome, and the superficial radial nerve for Wartenberg syndrome. This differential evaluation is critical because radial-sided wrist pain has numerous causes with distinct treatments, and De Quervain's is a clinical diagnosis that imaging can confirm or refute.

First-line management includes thumb spica splinting maintaining the wrist and thumb in neutral, anti-inflammatory medication, and activity modification avoiding repetitive pinching and twisting. Corticosteroid injection into the first dorsal compartment achieves resolution in 70-90% of primary cases. When septation is present, ultrasound-guided dual-compartment injection improves success rates. Surgical first dorsal compartment release is reserved for cases failing two to three injections and is highly effective with low recurrence. MRI findings of severe tendon degeneration or large subcompartment septation support earlier consideration of surgical release over repeated injection.