Review Question - QID 213017

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Intersection Syndrome Anatomy Extensor tendon compartments QID: 213017 (OBQ18.121)

QID 213017 (Type "213017" in App Search)

A 23-year-old professional rower presents with pain over the radial wrist when pronating and supinating his forearm. He denies any recent history of trauma and reports that the pain has been worsening over the past few months. On physical examination, there is crepitus over the distal forearm with wrist and thumb extension. Which of the following matches the correct extensor tendon compartment with the structures most likely affected in this pathology?

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Compartment 2; Abductor pollicis longus (APL) and extensor pollicis brevis (EPB) muscle bellies

69/2190

Compartment 2; Extensor carpi radialis brevis (ECRB) and extensor carpi radialis longus (ECRL) tendons

86%

1876/2190

Compartment 2; APL and EPB tendons

134/2190

Compartment 1; ECRB and ECRL muscle bellies

36/2190

Compartment 1; Extensor pollicis longus (EPL) tendon

56/2190

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This patient is presenting with intersection syndrome (IS), which affects the ECRB and ECRL.

IS in an inflammatory tendon disorder occurring at the area where the muscle bellies of the APL and EPB cross the underlying ECRB and ECRL tendons. It is an overuse disorder that is seen with sporting activities such as racket sports, rowing, weight lifting, canoeing, and skiing. Patients with IS have pain and tenderness on the radial side of the distal forearm that is associated with crepitus when flexing and extending the wrist. IS must be differentiated from de Quervain's tenosynovitis (DQT), which is a disorder of the first dorsal compartment (APL and EPB tendons). DQT is more common in women and often presents in patients over 40. Pregnant or lactating women also commonly present with DQT.

Skinner performed a review of intersection syndrome, also known as crossover tendinitis. The author reported that symptoms may worsen after pregnancy. He stated that IS is differentiated from DQT as it affects the first dorsal compartment. He concludes that having squeaking sensation may also differentiate the two diagnoses.

Sato et al. performed a study to determine the demographic characteristics of patients who were diagnosed with IS and compared that with DQT. They found that, compared to DQT, IS occurred more frequently in men and in the dominant hand. IS also occurred in a younger age group and presented with a much shorter duration of symptoms. They conclude that, regardless of age, a peripartum woman likely has DQT.

Illustration A is a photograph detailing the structures involved in IS and DQT. Illustrations B and C are photographs detailing the anatomic locations of pain in IS and DQT, respectively.

Incorrect Answers:
Answers 1 & 3: The APL and EPB are affected in DQT and are located in the first dorsal wrist compartment.
Answer 4: The ECRB and ECRL muscle bellies are located more proximally. The tendons are affected in IS and these structures are located in the second dorsal compartment.
Answer 5: The EPL is located in the third dorsal compartment and is not affected in IS.

ILLUSTRATIONS: