Clinical Considerations of First Extensor Wrist Compartment (FEWC) Variants and De Quervain’s Disease: A Review Study

Abstract

The first extensor wrist compartment (FEWC) displays significant variants. This review highlights all possible variants that may be associated with the occurrence and pathophysiology of de Quervain's tenosynovitis. A thorough search of PubMed and MEDLINE databases, following the PRISMA guidelines, was conducted from 2002 to 2022 to evaluate all FEWC variants, including the following: 1) the presence of an inter-tendinous septum, 2) the number of tendinous slips of the abductor pollicis longus (APL) and the extensor pollicis brevis (EPB) muscles, 3) their distal insertions and 4) the presence of a bony ridge within the FEWC. A total of 3878 wrists (1277 cadaveric and 1296 de Quervain patients) were included. Of the 1234 cadavers, a total of 701 (56.8%) were males and 533 (43.2%) were females. Regarding the 883 patients, 178 (20.2%) of them were males and 705 (79.8%) were females. An inter-tendinous septum was identified in 42.9% (47% of the patients' wrists compared to 39.3% of the cadaveric wrists, p<0.0001). Cadaveric wrists presented two or more slips for the APL in a significantly higher percentage (92.5%, p < 0.0001) compared to de Quervain patients' wrists (74.5%). Regarding the EPB muscle, de Quervain patients' wrists had a single slip in 93% (p=0.0007) and two or more slips in 3.6%, compared to cadaveric wrists (a single slip in 87%, and two or more slips in 11%, p< 0.0001). A bony ridge over the radial styloid process was recorded in 58.9% of the cadaveric wrists compared to 17.8% of the patients' wrists (p < 0.0001). Remarkable diversity concerning the structures within the FEWC was reported. The presence of an inter-tendinous septum dividing the FEWC and a single EPB muscle slip is more likely to be found in patients with de Quervain's disease.

Variations in the Extensor Pollicis Brevis-Extensor Pollicis Longus Tendon Complex

“…EPB tendon variations are important for clinical practice. EPB variations may directly impact the development of de Quervain's disease by altering the mechanical conditions within the first extensor compartment of the wrist [ 3 ]. Interestingly, the incidence of distal EPB insertion on the distal phalanx is higher in patients with separate first compartments, suggesting a relationship between EPB variation and inter-tendinous septum [ 12 ].…”

“…During extension of the thumb, the extensor pollicis longus (EPL), extensor pollicis brevis (EPB), and extensor hood all originate from the metacarpophalangeal (MP) to the interphalangeal (IP) joint, forming a complex [ 1 - 2 ]. Among the elements that make up this complex, the EPB is known to have a large number of variations [ 3 - 5 ]. Because the muscle bodies of the EPB and abductor pollicis longus (APL) are often continuous, the EPB has been considered a separate structure from the APL [ 6 ].…”

“…Conversely, recent studies have revealed that limb muscles and tendons have different ontogenetic processes [ 8 - 9 ]. Although there are many reports on the running of the EPB tendons, the classification of tendon insertions differs among reports and is not unified [ 1 - 3 , 5 , 10 - 16 ]. Thus, the present study aimed to observe the running and insertion of the EPB tendons in detail and examine their classification from the perspective of the process of tendon development.…”