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Purpose: Interphalangeal joint stabilization often is performed concomitantly with tendon transfers that restore key pinch (lateral pinch) to the paralyzed thumb. The goal of this study was to measure the effect of interphalangeal joint stabilization via percutaneous pin fixation on the thumb-tip force produced by the flexor pollicis longus (FPL).
Methods: We applied 10 N of force to the tendon of the FPL in 7 cadaveric specimens and measured the resulting thumb-tip force in the intact thumb and after stabilization of the interphalangeal joint.
Results: The nominal thumb-tip force was approximately 6 times less than the applied force and was directed primarily in the thumb's plane of flexion-extension at an oblique angle of 44 degrees relative to the palmar direction (the direction that is perpendicular to the thumb tip in the plane). Joint stabilization increased significantly the nominal force and oriented the force more toward the palmar direction (ie, decreased the obliqueness of the force).
Conclusions: After paralysis and a tendon transfer to the paralyzed FPL the FPL is often the only muscle actuating the thumb. We conclude that the oblique nominal force direction is prone to cause the thumb to slip during pinch. Joint stabilization, however, has the capacity to reduce the tendency for slippage because it rotates the force toward the palmar direction.
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http://dx.doi.org/10.1016/j.jhsa.2004.07.005 | DOI Listing |
J Biomech
October 2025
Swarthmore College, Department of Engineering, 500 College Ave, Swarthmore, PA 19081, United States. Electronic address:
Thumb tendon transfer surgical procedures in patients with cervical spinal injury engage the paralyzed flexor pollicis longus (FPL) muscle to enable lateral pinch grasp. However, functional outcomes are mixed, in part because the FPL cannot consistently produce force at the thumb-tip to promote a stable grasp. We used simulation to investigate whether a multiple recipient muscle tendon transfer, targeting sets of paralyzed muscles driven by a single donor muscle, could outperform a single recipient muscle tendon transfer with the FPL alone and restore lateral pinch.
View Article and Find Full Text PDFJ Hand Microsurg
September 2025
Department of Reconstructive Surgery and Hand Surgery, Azienda Ospedaliera Universitaria delle Marche, 60126, Ancona, Italy.
Introduction: The thumb plays a crucial role in hand biomechanics, particularly in fine and forceful grips. Due to its functional importance, trauma involving the thumb is frequent. In cases of pulp tissue loss, Moberg's 1964 principles for functional thumb reconstruction remain a cornerstone in hand surgery.
View Article and Find Full Text PDFOper Orthop Traumatol
February 2025
Handchirurgie, SRO AG Spital Region Oberaargau, St. Urbanstr. 67, 4900, Langenthal, Schweiz.
Objective: Improving the overall function of the hand by resection of the second ray applying the palmar approach in order to achieve an aesthetically pleasing postoperative result.
Indications: Mechanically disturbing proximal limb stump, high degree of instability of the index finger, chronic infection/osteomyelitis of the index finger, dystrophic index finger with impaired circulation, degloving injury, malformations, malignant tumours of the index finger, aesthetic improvement after index finger amputation.
Contraindications: Loss of grip strength that cannot be tolerated.
Annu Int Conf IEEE Eng Med Biol Soc
July 2023
A previous study showed in situ measurements of thumb-tip forces produced by muscles vary substantially among cadaveric specimens. Potential sources of variability include inter-specimen anatomic differences and postural deviations from the nominal posture in which the specimens were tested. This study aimed to theoretically determine the variation in thumb-tip force caused by inter-specimen differences in thumb anatomy and posture.
View Article and Find Full Text PDFJ Biomech
September 2023
J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL, USA. Electronic address:
Obtaining large biomechanical datasets for machine learning is an ongoing challenge. Physics-based simulations offer one approach for generating large datasets, but many simulation methods, such as computed muscle control (CMC), are computationally costly. In contrast, interpolation methods, such as inverse distance weighting (IDW), are computationally fast.
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