First Compartment Extensor Tendons
Principal Investigator: Peter C. Amadio, M.D.
Project Coordinator: Chunfeng Zhao, M.D. — zhao.chunfeng@mayo.edu
Extensor Tendon Gliding Resistance and Implications for de Quervain's Disease
The etiology of de Quervain's disease is still unknown, but repetitive motion, awkward wrist position and septation within the first dorsal compartment are considered to be possible causes. The purpose of this study was to measure the gliding resistance of the extensor pollicis brevis (EPB) and abductor pollicis longus (APL) tendons within the first dorsal compartment using human cadavers. The results showed differences in EPB (but not APL) gliding resistance between speciemens with and without septation and 60 degrees wrist flexion had highest gliding resistance. Finkelstein's test is the classic diagnostic test for de Quervain's disease. At the position simulating Finkelstein's test (30 degrees ulnar deviation with neutral extension/flexion), we measured excursion and terminal gliding resistance of EPB and APL tendons within the first compartment. In the position of Finkelsteins's test the EPB tendon had a greater distal excursion, and a higher bulk and tethering effect compared to the APL. These results suggest that an abnormal Finkelstein's test reflects pathology of the EPB more than it does the APL.
Gliding Resistance of Extensor Tendons within the Extensor Retinaculum
The etiology of spontaneous extensor pollicis longus (EPL) tendon rupture is still largely unknown. It is possible that friction within the sheath may play a role. The purposes of this study were to compare gliding resistance of the EPL tendon with that of the extensor digitorum communis of the index finger (EDC II) tendon and to find the wrist position that gives the EPL tendon the least gliding resistance.
The gliding resistance of the EPL tendon was higher than the EDC II tendon. For the EPL tendon, the gliding resistance was significantly greater in 60 degrees wrist flexion compared to the other wrist positions tested. Positioning the wrist close to neutral flexion/extension, and in some ulnar deviation, minimizes the friction within the EPL sheath, which may be advantageous for splinting patients at risk for EPL rupture.
Effect of Oblique Pulley on Extensor Tendon Gliding Resistance
After tendon repair, it is important for the repair site to pass smoothly under the edge of the pulley to promote gliding and reduce the risk of adhesion or rupture. The purpose of this study was to assess the effect of a partial excision of the oblique pulley on the gliding resistance of the flexor pollicis longus tendon after repair in vitro. Previous studies suggest that the trimming of the pulley would not result in any significant mechanical disadvantage if other parts of the pulley system are intact. However, our results suggest that the gliding resistance is increased in the trimmed pulley compared to the intact after tendon repair. Thus, the oblique pulley should be left intact if possible.
