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Relative Motion Extension Splint For Treatment Of Flexor Tendon Adhesions: Proof of Concept
Nicole Badalyan, BE, BS
1, Brian Bueno, MD
2, Jared Escobar, MD
1, Alta Fried, OTR/L, CHT
3, Brian Katt, MD
1, Ajul Shah, MD
4; Emily Van Kouwenberg, MD
5(1)Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ, (2)NYU Langone Orthopedic Hospital, New York, NY, (3)Atlantic Hand Therapy Center, Toms River, NJ, (4)The Center for Hand and Upper Extremity Surgery, Shrewsbury, NJ, (5)Plastic and Reconstructive Surgery, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ
Hypothesis: Incorporating RMES splints during active range of motion exercises will position flexor tendons in relative extension, increasing total flexor tendon excursion during flexion exercises. Enhanced tendon excursion and differential glide between the FDS and FDP tendons can facilitate adhesion lysis.
Methods: A frozen cadaveric upper extremity was dissected to expose the middle finger FDS and FDP tendons and pulleys. The arm was mounted vertically with a fiberglass cast on the wrist to maintain it in neutral position. Sutures were placed at the FDS and FDP tendons at the wrist to hold a 10N weight, to replicate active contraction of the FDS or FDP muscle bellies. The relative starting positions of the tendons were marked at different levels (IIA, IIB, IIC). Differential glide between the FDS and FDP tendons were measured at each level under six test conditions: isolated FDS motion with and without RMES, isolated FDP motion with and without RMES, and non-isolated FDP motion with and without RMES. Non-isolated FDP motion was performed to represent active composite fist motion. After each test condition, the distance between the marked starting points at each level was measured to determine the distance of differential glide between the tendons. Each condition was measured three times by three separate individuals to confirm consistency.
Results: The addition of RMES during isolated FDS motion increased glide differential at zones IIA and IIB (0-1mm to 3mm), while zone IIC remained unchanged (3mm). The addition of RMES to isolated FDP exercises increased differential glide only at zone IIC (4mm to 6mm), while zones IIA and IIB remained unchanged (3mm and 4mm, respectively). The addition of RMES to non-isolated FDP exercises increased differential glide across all zones: IIA (4mm to 7mm), IIB (8mm to 10mm), and IIC (11mm to 13mm).
Summary Points: Our study measured the differential glide between FDS and FDP tendons in zone II with and without RMES and showed increased differential glide when RMES was in place. However, this study also shows that differential glide is not uniform throughout zone II which may explain why some zones are more prone to adhesion formation than others and why some adhesions are more resistant to therapy. This study demonstrates that the use of RMES during active range of motion exercises increases tendon excursion and the differential glide between the FDS and FDP tendons.
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