Case of the Week – Distal Intersection Syndrome

Dr Tom Entwisle

MRI in a 53 year old woman with persisting dorsal wrist pain after a fall 6 months previously demonstrates a short segment of moderate grade EPL tendinopathy and tenosynovitis (red arrow) as it passes around Lister’s Tubercle ( * ) and over the ECRB and then ECRL tendons. The EPL tendon demonstrates grey / intermediate signal thickening in keeping with tendinopathy. Multiple delaminations are present. There is high signal fluid in the thickened tendon sheath consistent with tenosynovitis. There is no reactive periostitis or marrow oedema in the region. Note the 4mm dorsal scapholunate ganglion (yellow arrow) and the small amount of
fluid around the ECRB tendon distally (blue arrow).

 

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Anatomy & Pathology

The EPL (extensor compartment 3) and the ECRB and ECRL tendons (extensor compartment 2) intersect distal to the radiocarpal joint and Lister’s tubercle. The tubercle acts as a pulley, altering the angle of the EPL tendon so that it crosses superficial to ECRB and ECRL.

There are several anatomical factors that contribute to the pathology. Lister’s tubercle can cause mechanical irritation / friction due to the change in the angle of pull. Extensor compartment 2 (ECRB and ECRL) communicates with compartment 3 (EPL) in this region, allowing inflammation to spread. The extensor retinaculum may cause constriction of the tendons. Finally, EPL has a watershed vascular supply in this
region which makes it vulnerable to ischaemia and limits its ability to heal.

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Clinical

Most patients present with dorsal wrist pain and swelling, sometimes after a traumatic event. Autoimmune diseases such as rheumatoid arthritis or lupus are risk factors.cotw_july3

Distal intersection syndrome involving compartments 2 and 3 distal to the wrist is less common than forearm intersection syndrome involving APL and EPB (extensor compartment 1) and ECRL and ERCB (compartment 2) proximal to the extensor retinaculum (figure to the right).

Treatment

If not related to distal radial fracture or autoimmune disease, then most cases of distal intersection syndrome tend to be mild and respond well to conservative treatment (immobilisation, physical therapy, NSAIDS). in severe cases where there is tendon rupture, surgery is required but often difficult due to retraction and the poor quality of residual tendon. A tendon transfer or graft may be needed in these cases.

 

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References

  1. Parellada AJ, Gopez AG, Morrison WB, Sweet S, Leinberry CF, Reiter SB, Kohn M. Distal intersection tenosynovitis of the wrist: a lesser-known extensor tendinopathy with characteristic MR imaging features. Skeletal Radiol. 2007 Mar;36(3):203-8.
  2. RadSource http://radsource.us/tendon-intersection-syndromes/