Extensor Pollicis Brevis Subcompartment Characteristics in the 1st Dorsal Extensor Compartment: An Anatomic and Radiographic Study
Brittany J. Behar, MD, Emma Dahmus, BS, Logan Carr, MD, John Ingraham, MD.
Penn State Hershey Medical Center, Hershey, PA, USA.
PURPOSE: We aim to characterize the 1st dorsal compartment anatomy and examine radiographic correlation with the presence of EPB subsheath.
METHODS: First, freshly-preserved cadaveric arms were dissected and data including the presence or absence of EPB subsheath were noted. Standard wrist x-rays were obtained. Then a retrospective review of DeQuervain’s patients with 1st dorsal compartment releases was completed. Those with notation of the presence or absence of a subsheath and preoperative x-rays were included. Radiologists reviewed x-rays for an osseous ridge comparing them to cadaveric specimen standards.
RESULTS: Nine of the 10 arms were male. The APL tendon had a mean of 3.3 ± 1.3 slips. The EPB tendon had one slip in all specimens. Seven compartments (70%) had an identifiable EPB subcompartment and four (57%) were thick. An osseous ridge was seen in 2 specimens, both with a thick subcompartment. The two arms with osseous ridges revealed radiopaque ridges on x-ray. Radiologists’ x-ray reviews revealed an osseous ridge in 58.9% of reads. Interrater reliability using Fleiss’ kappa was 0.33 ± 0.05. Presence or absence of EPB subsheath correlated with presence or absence of an osseous ridge in 48% of radiologists’ reads.
CONCLUSION: Most EPB subcompartments were thick and well-defined which may contribute to non-operative failures. Preoperative radiographs can help screen patients for early referral for ultrasound guided injection or surgical intervention in refractory cases.cases.
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