Wrist osteoarthritis is a degenerative disease that causes severe pain. This pain limits functional abilities and frequently causes the inability to work. One of the most reliable methods to reduce pain is surgery. However, current surgical treatments permanently decrease wrist range of motion and grip strength. This loss of grip strength is particularly detrimental because it limits patient's abilities to perform activities ofdaily living, including picking up a saucepan and opening a door. The objective of this proposal is to identify the biomechanical factors that limit grip strength following two procedures to treat osteoarthritis: proximal row carpectomy (PRC) and scaphoid-excision four-corner fusion (SE4CF). PRC and SE4CF are of particular interest because there is no consensus regarding which is better at preserving grip strength, even though there are a large number of retrospective studies comparing these procedures. Additionally, PRC and SE4CF change the biomechanical design of the wrist in different ways, suggesting that different factors limit grip strength following each procedure. In the proposed study, post-operative muscle moment-generating (Aim 1) and force-generating parameters (Aim 2) will be measured and evaluated in the context of post-operative impairments in strength (Aim 3).
In Aim 1, a cadaveric experiment will be conducted to measure the muscle moment arms of the primary wrist and extrinsic thumb muscles following simulated PRC and SE4CF.
In Aim 2, post-operative muscle fiber length of the primary wrist muscles will be measured in vivo using ultrasound. In Am 3, post-operative wrist and hand strength will be measured in vivo, and these data will be used in musculoskeletal computer models to evaluate how changes in moment arm and fiber length influence wrist, pinch, and grip strength. Completion of this work will improve the scientific understanding of how the design of the wrist influences the forces produced by the hand, and thereby affects hand function. Ultimately, clinicians will be able to use knowledge gained from this study to develop rehabilitation protocols and surgical techniques to overcome post-operative impairments, thereby improving patient outcomes and quality of life. Through this research, the applicant will gain experience in performing experiments involving both cadavers and human subjects as well as using computer modeling to enhance the interpretation of experimental results. The applicant will receive additional training on teaching effectively, collaborating on interdisciplinary teams, and presenting to both scientific and clinical audiences. These experiences will teach the applicant technical and professional skills that are essential for a lifelong research career.

Public Health Relevance

Surgical treatment of wrist osteoarthritis, a painful degenerative disease, relieves pain, but impairs hand strength;how surgically altering the wrist influences hand strength is not well understood. The proposed research will identify the biomechanical factors that limit hand strength following two surgeries used to treat wrist osteoarthritis: proximal row carpectomy (PRC) and scaphoid-excision four-corner fusion (SE4CF). This study will enhance the understanding of how these procedures influence both wrist and hand function, and aid clinicians in developing rehabilitation strategies and surgical techniques to overcome impairment.

National Institute of Health (NIH)
National Institute on Aging (NIA)
Predoctoral Individual National Research Service Award (F31)
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Special Emphasis Panel (ZRG1-F10B-S (20))
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Joseph, Lyndon
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Northwestern University at Chicago
Biomedical Engineering
Schools of Engineering
United States
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Nichols, Jennifer A; Bednar, Michael S; Wohlman, Sarah J et al. (2017) Connecting the wrist to the hand: A simulation study exploring changes in thumb-tip endpoint force following wrist surgery. J Biomech 58:97-104
Nichols, Jennifer A; Bednar, Michael S; Havey, Robert M et al. (2017) Decoupling the Wrist: A Cadaveric Experiment Examining Wrist Kinematics Following Midcarpal Fusion and Scaphoid Excision. J Appl Biomech 33:12-23
Nichols, Jennifer A; Bednar, Michael S; Murray, Wendy M (2016) Surgical Simulations Based on Limited Quantitative Data: Understanding How Musculoskeletal Models Can Be Used to Predict Moment Arms and Guide Experimental Design. PLoS One 11:e0157346
Nichols, Jennifer A; Bednar, Michael S; Havey, Robert M et al. (2015) Wrist salvage procedures alter moment arms of the primary wrist muscles. Clin Biomech (Bristol, Avon) 30:424-30