Background: Procedures involving release of the third dorsal wrist compartment have been thought to transpose the extensor pollicis longus (EPL) tendon from its anatomical position. Few studies, however, have reported on the effects this might have on function and mechanics of the thumb. We analyzed the impacts of intact extensor retinaculum, release of the third dorsal compartment, and removal of Lister’s tubercle on thumb extension.
Methods: A total of 15 fresh-frozen cadaveric upper extremities (eight male, seven female; mean age, 52 years; range, 38-59 years) were used. For each specimen, three phases of testing were analyzed: the extensor retinaculum was intact, third dorsal compartment was released, and Lister’s tubercle was released. Force-displacement measurements were obtained to determine maximum extension and stiffness of the thumb by applying 1 N increments on the EPL until full extension of the thumb occurred. A one-way analysis of variance was used for statistical comparison.
Results: In 14 of 15 specimens, the EPL tendon transposed during the first trial after release of the extensor retinaculum. No significant difference in mean maximum extension or stiffness of the thumb was found (P = 0.45 and P = 0.74, respectively).
Conclusion: Functional loss of thumb extension may not occur with EPL transposition after release of the third dorsal compartment or removal of Lister’s tubercle. In patients with weakness in thumb extension, repairing the third dorsal compartment or creating a new pulley may not be effective.
Salas, Christina; Drew K. Newhoff; Zainab Cheema; Allison A. Richards; Deana M. Mercer; Amanda K. Medoro; Ahmed M. Afifi; Moheb S. Moneim; and John M. Veitch. "Third Extensor Compartment Disruption and the Biomechanics of Thumb Extension." UNM Orthopaedic Research Journal 4, 1 (2015). https://digitalrepository.unm.edu/unm_jor/vol4/iss1/19