Which of the following is true regarding De Quervain’s tenosynovitis?

Correct Answer: A. It affects APL and EPB

De Quervain's tenosynovitis is a stenosing tenosynovitis affecting the first dorsal compartment of the wrist. This compartment contains two tendons: the Abductor Pollicis Longus (APL) and the Extensor Pollicis Brevis (EPB). The condition arises from repetitive wrist radial deviation and thumb abduction movements, causing inflammation and thickening of the synovial sheath. The hallmark clinical presentation is pain over the radial styloid process, positive Finkelstein's test (pain on passive thumb flexion with wrist ulnar deviation), and swelling in the first dorsal compartment. This is distinct from other dorsal compartment pathologies—the second compartment contains ECRB and ECRL, the third contains EIP, and so forth. The discriminating anatomical fact is that APL and EPB are the only two tendons sharing the first dorsal compartment at the wrist, making them the exclusive structures involved in De Quervain's tenosynovitis. Understanding this compartmental anatomy is essential for diagnosis and treatment planning in Indian clinical practice.

Why the other options are wrong

B. Fingers are held in mild extension — This describes the posture in intrinsic plus position or conditions affecting finger flexors/extensors, not thumb pathology. De Quervain's affects the thumb specifically, and the thumb is held in mild flexion and adduction (not extension) due to pain and protective muscle guarding. The fingers themselves are not characteristically held in any fixed posture in De Quervain's. This is an NBE trap confusing thumb vs. finger involvement. C. Most common involvement is index finger — De Quervain's tenosynovitis affects the thumb, not the index finger. The condition involves the first dorsal compartment at the wrist (APL and EPB), which are thumb muscles. The index finger is supplied by the second dorsal compartment (ECRB, ECRL). This option confuses compartmental anatomy and is a classic NBE distractor for students who do not clearly map tendons to compartments. D. Treatment is surgery — Conservative management is first-line in De Quervain's tenosynovitis, including rest, NSAIDs, thumb spica splinting, and corticosteroid injection into the first dorsal compartment sheath. Surgery (first dorsal compartment release) is reserved for refractory cases (typically after 6–12 weeks of conservative therapy failure). In Indian clinical practice, most cases resolve with conservative measures. This option reflects a common misconception that tenosynovitis requires immediate surgical intervention.

High-Yield Facts

Mnemonics

First Dorsal Compartment = APL + EPB Abductor Pollicis Longus and Extensor Pollicis Brevis share the first dorsal compartment. Remember: APL abducts the thumb (moves it away), EPB extends the thumb IP joint. Both are thumb muscles in the same compartment. Dorsal Compartments (Wrist) – Quick Recall 1st = APL + EPB (thumb); 2nd = ECRB + ECRL (wrist); 3rd = EIP (index); 4th = EDC + EIP (fingers); 5th = EDM (little); 6th = ECU (ulnar). De Quervain's = 1st compartment only.

NBE Trap

NBE pairs "fingers held in extension" with De Quervain's to trap students who confuse thumb pathology with finger postures, and pairs "index finger involvement" to test whether students can map tendons to dorsal compartments correctly.

Clinical Pearl

In Indian clinical practice, De Quervain's is common in women aged 30–50 and in workers with repetitive thumb-pinching activities (e.g., tailors, agricultural workers). A single corticosteroid injection into the first dorsal compartment sheath under ultrasound guidance often resolves symptoms within 2–4 weeks, avoiding surgery in >80% of cases.

_Reference: Bailey & Love Ch. 65 (Hand Surgery); Robbins Ch. 26 (Musculoskeletal Pathology)_