Zong-Ming Li

Interests

Research

Carpal tunnel syndrome, Hand Arthritis, Musculoskeletal Imaging, Biomechanics and motor control of the hand, Neuromuscular control, Musculoskeletal Biomechanics and Rehabilitation, Biomechanics of shoulder arthroplasty, Biomechanical modeling, Biomechanics of orthopaedic implants, Experimental methods in biomechanics, Biorobotics, EMG, Finger coordination, Finger joint stiffness, Gait analyses, Hand biomechanics, Human motor redundancy problem, Human movement analyses, Ligament and tendon mechanics and mechanobiology, Mathematical (optimization) modeling, Molecular mechanisms of flexor tenosynovitis and ligament hypertrophy, Motion analysis, Musculoskeletal Ultrasonography, Neural network modeling, Neuromuscular control of hand and upper extremity, Neural rehabilitation, Posture and balance, Rehabilitation engineering, Shoulder biomechanics, Ultrasonic imaging, Wrist kinematics, Wrist morphometry

Teaching

Biomechanics

Courses

Scholarly Contributions

Books

• Li, Z., Wayne, J. S., Chen, C., & Woo, K. (2012). Tributes to Savio L-Y Woo on His 70th Birthday. doi:10.1142/8477

Journals/Publications

• Jordan, D., Elfar, J., Kwoh, C., & Li, Z. (2024). Estimation of radiographic joint space of the trapeziometacarpal joint with computed tomographic validation. Journal of Medical Imaging, 11(2). doi:10.1117/1.JMI.11.2.024001
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  Purpose: Joint space width (JSW) is a common metric used to evaluate joint structure on plain radiographs. For the hand, quantitative techniques are available for evaluation of the JSW of finger joints; however, such techniques have been difficult to establish for the trapeziometacarpal (TMC) joint. This study aimed to develop a validated method for measuring the radiographic joint space of the healthy TMC joint. Approach: Computed tomographic scans were taken of 15 cadaveric hands. The location of a JSW analysis region on the articular surface of the first metacarpal was established in 3D space and standardized in a 2D projection. The standardized region was applied to simulated radiographic images. A correction factor was defined as the ratio of the CT-based and radiograph-based joint space measurements. Leave-one-out validation was used to correct the radiograph-based measurements. A t-test was used to evaluate the difference between CT-based and corrected radiograph-based measurements (α ¼ 0.05). Results: The CT-based and radiograph-based measurements of JSW were 3.61 ∓ 0.72 mm and 2.18 ∓ 0.40 mm, respectively. The correction factor for radiograph-based joint space was 1.69 ∓ 0.41. Before correction, the difference between the CT-based and radiograph-based joint space was 1.43 mm [95% CI: 0.99 − 1.86 mm; p < 0.001]. After correction, the difference was −0.11 mm [95% CI: −0.63 − 0.41 mm; p ¼ 0.669]. Conclusions: Corrected measurements of radiographic TMC JSW agreed well with CT-measured JSW. With in-vivo validation, the developed methodology has potential for automated and accurate radiographic measurement of TMC JSW.
• Li, Z. (2024). Estimation of radiographic joint space of the trapeziometacarpal joint with computed tomographic validation. Journal of Medical Imaging, 11(02). doi:10.1117/1.jmi.11.2.024001
• Li, Z., Coleman, K., Zhang, H., Kwoh, C. K., & Li, V. (2024). Trapeziometacarpal Joint Laxity in Pre- and Post-Menopausal Females by Dynamic Ultrasound. Journal of Orthopaedics and Sports Medicine, 6(4). doi:DOI:10.26502/josm.511500171
• Li, Z., Elfar, J. C., Kwoh, C. K., Jordan, D. B., & Daulat, S. (2024). Trapeziometacarpal joint movement during pinching measured by ultrasonography. Osteoarthritis Imaging, 4(4). doi:https://doi.org/10.1016/j.ostima.2024.100252
• Zhang, H., Elfar, J., Kwoh, C., & Li, Z. (2024). Shear wave elastography of transverse carpal ligament increased with simulated carpal tunnel pressure. Journal of Orthopaedic Surgery and Research, 19(1). doi:10.1186/s13018-024-04874-x
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  Background: Elevation of carpal tunnel pressure is known to be associated with carpal tunnel syndrome. This study aimed to correlate the shear wave elastography in the transverse carpal ligament (TCL) with carpal tunnel pressures using a cadaveric model. Methods: Eight human cadaveric hands were dissected to evacuate the tunnels. A medical balloon was inserted into each tunnel and connected to a pressure regulator to simulate tunnel pressure in the range of 0-210 mmHg with an increment of 30 mmHg. Shear wave velocity and modulus was measure in the middle of TCL. Results: SWV and SWE were significantly dependent on the pressure levels (p < 0.001), and positively correlated to the tunnel pressure (SWV: R = 0.997, p < 0.001; SWE: R = 0.996, p < 0.001). Regression analyses showed linear relationship SWV and pressure (SWV = 4.359 + 0.0263 * Pressure, R2 = 0.994) and between SWE and pressure (SWE = 48.927 + 1.248 * Pressure, R2 = 0.996). Conclusion: The study indicated that SWV and SWE in the TCL increased linearly as the tunnel pressure increased within the current pressure range. The findings suggested that SWV/SWE in the TCL has the potential for prediction of tunnel pressure and diagnosis of carpal tunnel syndrome.
• Abraham, I., Lewandrowski, K., Elfar, J. C., Li, Z., Fiorelli, R. A., Pereira, M. G., Lorio, M. P., Burkhardt, B. W., Oertel, J. M., Winkler, P. A., Yang, H., León, J. F., Telfeian, A. E., Dowling, A., Vargas, R. A., Ramina, R., Asefi, M., de Carvalho, P. S., Defino, H., , Moyano, J., et al. (2023). Randomized Clinical Trials and Observational Tribulations: Providing Clinical Evidence for Personalized Surgical Pain Management Care Models. Journal of personalized medicine, 13(7), 1044. doi:https://doi.org/10.3390/jpm13071044
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  Proving clinical superiority of personalized care models in interventional and surgical pain management is challenging. The apparent difficulties may arise from the inability to standardize complex surgical procedures that often involve multiple steps. Ensuring the surgery is performed the same way every time is nearly impossible. Confounding factors, such as the variability of the patient population and selection bias regarding comorbidities and anatomical variations are also difficult to control for. Small sample sizes in study groups comparing iterations of a surgical protocol may amplify bias. It is essentially impossible to conceal the surgical treatment from the surgeon and the operating team. Restrictive inclusion and exclusion criteria may distort the study population to no longer reflect patients seen in daily practice. Hindsight bias is introduced by the inability to effectively blind patient group allocation, which affects clinical result interpretation, particularly if the outcome is already known to the investigators when the outcome analysis is performed (often a long time after the intervention). Randomization is equally problematic, as many patients want to avoid being randomly assigned to a study group, particularly if they perceive their surgeon to be unsure of which treatment will likely render the best clinical outcome for them. Ethical concerns may also exist if the study involves additional and unnecessary risks. Lastly, surgical trials are costly, especially if the tested interventions are complex and require long-term follow-up to assess their benefit. Traditional clinical testing of personalized surgical pain management treatments may be more challenging because individualized solutions tailored to each patient's pain generator can vary extensively. However, high-grade evidence is needed to prompt a protocol change and break with traditional image-based criteria for treatment. In this article, the authors review issues in surgical trials and offer practical solutions.
• Hawk, J., Zhang, H., Margolis, D., & Li, Z. (2021). Robot and ultrasound assisted needle insertion to the transverse carpal ligament. Clinical Biomechanics, 101(1), 105851. doi:10.1016/j.clinbiomech.2022.105851
• Jordan, D., Zhang, H., & Li, Z. (2023). Spatial Relationship of the Median Nerve and Transverse Carpal Ligament in Asymptomatic Hands. Journal of Biomechanical Engineering, 145(3). doi:10.1115/1.4056290
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  The spacing between the median nerve and transverse carpal ligament (TCL) within the carpal tunnel can potentially affect the nerve morphology. This study aimed to quantify the spatial relationship between the median nerve and transverse carpal ligament in asymptomatic hands. Twelve subjects were recruited to image the carpal tunnel using robot-assisted ultrasound. The median nerve and TCL were segmented from each image and three-dimensionally reconstructed using kinematic information from the robot. The TCL-median nerve distance, nerve cross-sectional area, circularity, and position were measured along the entirety of the nerve length within the carpal tunnel. Results were averaged at every 5% of nerve length. At the nerve length percentages of 0% (distal), 25%, 50%, 75%, and 100% (proximal), the TCL-median nerve distance (±SD) was 0.7±0.4, 0.7±0.2, 0.5±0.2, 0.5±0.2, and 0.6±0.3 mm, respectively. The corresponding nerve cross-sectional area was 9.4±1.9, 10.6±2.6, 11.2±2.1, 11.2±1.7, and 9.7±1.9mm2. A one-way analysis of variance showed no significant differences between the respective percentages of nerve length for TCL-median nerve distance (p=0.219) and cross-sectional area (p=0.869). Significant (p
• Lewandrowski, K., Elfar, J. C., Li, Z., Burkhardt, B. W., Lorio, M. P., Winkler, P. A., Oertel, J. M., Telfeian, A. E., Dowling, A., Vargas, R. A., Ramina, R., Abraham, I., Assefi, M., Yang, H., Zhang, X., Ramírez León, J. F., Fiorelli, R. K., Pereira, M. G., de Carvalho, P. S., , Defino, H., et al. (2023). The Changing Environment in Postgraduate Education in Orthopedic Surgery and Neurosurgery and Its Impact on Technology-Driven Targeted Interventional and Surgical Pain Management: Perspectives from Europe, Latin America, Asia, and The United States. Journal of personalized medicine, 13(5), 852. doi:https://doi.org/10.3390/jpm13050852
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  Personalized care models are dominating modern medicine. These models are rooted in teaching future physicians the skill set to keep up with innovation. In orthopedic surgery and neurosurgery, education is increasingly influenced by augmented reality, simulation, navigation, robotics, and in some cases, artificial intelligence. The postpandemic learning environment has also changed, emphasizing online learning and skill- and competency-based teaching models incorporating clinical and bench-top research. Attempts to improve work-life balance and minimize physician burnout have led to work-hour restrictions in postgraduate training programs. These restrictions have made it particularly challenging for orthopedic and neurosurgery residents to acquire the knowledge and skill set to meet the requirements for certification. The fast-paced flow of information and the rapid implementation of innovation require higher efficiencies in the modern postgraduate training environment. However, what is taught typically lags several years behind. Examples include minimally invasive tissue-sparing techniques through tubular small-bladed retractor systems, robotic and navigation, endoscopic, patient-specific implants made possible by advances in imaging technology and 3D printing, and regenerative strategies. Currently, the traditional roles of mentee and mentor are being redefined. The future orthopedic surgeons and neurosurgeons involved in personalized surgical pain management will need to be versed in several disciplines ranging from bioengineering, basic research, computer, social and health sciences, clinical study, trial design, public health policy development, and economic accountability. Solutions to the fast-paced innovation cycle in orthopedic surgery and neurosurgery include adaptive learning skills to seize opportunities for innovation with execution and implementation by facilitating translational research and clinical program development across traditional boundaries between clinical and nonclinical specialties. Preparing the future generation of surgeons to have the aptitude to keep up with the rapid technological advances is challenging for postgraduate residency programs and accreditation agencies. However, implementing clinical protocol change when the entrepreneur-investigator surgeon substantiates it with high-grade clinical evidence is at the heart of personalized surgical pain management.
• Li, Z. (2023). Non-surgical carpal arch space augmentation for median nerve decompression, A paper for ASME 2022 Savio L-Y. Woo Translational Biomechanics Medal.. Journal of Biomechanical Engineering, 145(8), 080801. doi:https://doi.org/10.1115/1.4056651
• Li, Z. (2023). Carpal arch space increased by volar force applied to the skin surface above the carpal tunnel. Clinical Biomechanics. doi:10.1016/j.clinbiomech.2023.105888
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  Carpal arch space augmentation can help decompress the median nerve. The augmentation can be achieved by mechanical manipulations utilizing the biomechanics of the tunnel structure. The purpose of this study was to expand the carpal arch in vitro by applying volar forces on the surface of the wrist.The mechanism was implemented in eight cadaver hands by attaching a volar force transmitter to the palmar surface of the wrist and pulling the transmitter volarly at six force levels (0, 3, 6, 9, 12, and 15 N). Ultrasound images of the cross section at the distal carpal tunnel were collected for morphological analysis.The carpal arch height, width, and area were significantly altered by the volarly applied force (P < 0.001). The arch height and area were increased but the arch width was decreased by the force. Pearson's correlation coefficient showed that there was a positive correlation between the arch height and force magnitude; and between the arch area and force magnitude. A negative correlation existed between the arch width and force magnitude (P < 0.001). The magnitude of change of the arch height, width, and area was increased as the force magnitude increased.This study demonstrated that applying external forces on the wrist skin to increase the carpal arch space was feasible. The magnitude of the force influenced its effect on altering the carpal arch. Study limitations include small sample size and inclusion of male specimens. Future in vivo work is needed for clinical translation feasibility.
• Li, Z., & Jordan, D. (2023). Carpal tunnel mechanics and its relevance to carpal tunnel syndrome, https://doi.org/10.1016/j.humov.2022.103044. Human Movement Science, 87(2), 103044. doi:https://doi.org/10.1016/j.humov.2022.103044
• Li, Z., & Jordan, D. (2023). Carpal tunnel mechanics and its relevance to carpal tunnel syndrome. Human Movement Science, 87. doi:10.1016/j.humov.2022.103044
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  The carpal tunnel is an elaborate biomechanical structure whose pathomechanics plays an essential role in the development of carpal tunnel syndrome. The purpose of this article is to review the movement related biomechanics of the carpal tunnel together with its anatomical and morphological features, and to describe the pathomechanics and pathophysiology associated with carpal tunnel syndrome. Topics of discussion include biomechanics of the median nerve, flexor tendons, subsynovial tissue, transverse carpal ligament, carpal tunnel pressure, and morphological properties, as well as mechanisms for biomechanical improvement and physiological restoration. It is our hope that the biomechanical knowledge of the carpal tunnel will improve the understanding and management of carpal tunnel syndrome.
• Li, Z., Jordan, D., & Zhang, H. (2023). Spatial relationship of the median nerve and transverse carpal ligament in asymptomatic hands, https://doi.org/10.1115/1.4056290. Journal of Biomechanical Engineering.
• Li, Z., Lui, S., Roemerb, F., Bedricka, E., Guermazic, A., Sun, X., & Kwoh, C. K. (2023). Comparison of evaluation metrics of deep learning for imbalanced imaging data in osteoarthritis studies. Osteoarthritis and Cartilage, 31(9), 1242-1248. doi:10.1016/j.joca.2023.05.006
• Li, Z., Zhang, H., & Jordan, D. (2023). Carpal arch space increased by volar force applied to the skin surface above the carpal tunnel, https://doi.org/10.1016/j.clinbiomech.2023.105888. Clinical Biomechanics, 101, 105851. doi:https://doi.org/10.1016/j.clinbiomech.2023.105888
• Alsafar, F., & Li, Z. (2021). Thenar and hypothenar muscle coverage on the transverse carpal ligament. Journal of Wrist Surgery. doi:10.1055/s-0041-1735887
• Hawk, J., Daulat, S., Margolis, D., & Li, Z. (2022). Dose- and time-dependent effects of collagenase clostridium histolyticum injection on transverse carpal ligament elastic modulus and thickness in vitro. PLoS ONE, 17(12). doi:10.1371/journal.pone.0277187
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  A potential treatment for carpal tunnel syndrome is to biochemically alter the mechanical properties of the transverse carpal ligament (TCL) through Collagenase Clostridium Histolyticum (CCH) injection. The purpose of this study was to determine the time- and dose-dependent effects of CCH injection on TCL elastic modulus and thickness. Nine TCLs were dissected from cadaveric hands for this study. CCH doses of 50U, 100U, 150U, 200U, and 250U were injected into five points on the TCL, respectively. B-mode and shear wave elastography images were taken of each injection point using robot-assisted ultrasound imaging immediately after injection, as well as 2, 4, 6, 8, and 24 hours after injection. TCL thickness and mean shear wave speed were measured for each CCH dose at each time point. CCH doses of 200U and 250U decreased shear wave speed by 18.70% and 30.01% (p
• Jordan, D., & Li, Z. (2021). Cross-sectional changes of the distal carpal tunnel with simulated carpal bone rotation. Computer Methods in Biomechanics and Biomedical Engineering.
• Jordan, D., & Li, Z. (2022). Cross-sectional changes of the distal carpal tunnel with simulated carpal bone rotation. Computer Methods in Biomechanics and Biomedical Engineering, 25(14). doi:10.1080/10255842.2022.2028143
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  This study simulated the cross-sectional changes in the distal carpal tunnel resulting from inward rotations of the hamate and trapezium. Rotations which decreased the carpal arch width, increased the carpal arch area. For example, simultaneous rotation of 5 degrees around the hamate and trapezium centroids decreased the carpal arch width by 1.69 ± 0.17 mm and increased the carpal arch area by 6.83 ± 0.68 mm2. Although the bone arch area decreased, decompression of the median nerve would likely occur due to the adjacent location of the nerve near the transverse carpal ligament.
• Jun, B., Ricchetti, E., Li, Z., & Iannotti, J. (2021). Validation of a 3-D CT Imaging Method for Quantifying Implant Migration following Anatomic Total Shoulder Arthroplasty. https://doi.org/10.1002/jor.25170. Journal of Orthopaedic Research.
• Li, Z., Daulat, S., Hawk, J., & Margolis, D. S. (2022). Dose- and time-dependent effects of collagenase clostridium histolyticum injection on transverse carpal ligament elastic modulus and thickness in vitro.  https://doi.org/10.1371/journal.pone.0277187. PLOS ONE.
• Li, Z., Grandy, E. L., Jenkins, L., Norman, C., Bena, J., Hou, J., Evans, P. J., Seitz, W. H., & Kwoh, C. K. (2022). A preliminary study of radioulnar wrist compression in improving patient-reported outcomes of carpal tunnel syndrome https://doi.org/10.1186/s12891-022-05943-0. BMC Musculoskeletal Disorder.
• Li, Z., Grandy, E., Jenkins, L., Norman, C., Bena, J., Hou, J., Evans, P., Seitz, W., & Kwoh, C. (2022). A preliminary study of radioulnar wrist compression in improving patient-reported outcomes of carpal tunnel syndrome. BMC Musculoskeletal Disorders, 23(1). doi:10.1186/s12891-022-05943-0
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  Previous studies have shown radioulnar wrist compression augments carpal arch space. This study investigated the effects of radioulnar wrist compression on patient-reported outcomes associated with carpal tunnel syndrome. Subjects underwent thrice-daily (15 min each time 45 min daily) wrist compression over 4 weeks with an additional four weeks of follow-up without treatment. Primary outcomes included Boston Carpal Tunnel Questionnaire symptom and functional severity scales (SSS and FSS) and symptoms of numbness/tingling based on Visual Analog Scales. Our results showed that radioulnar wrist compression improved SSS by 0.55 points after 2 weeks (p < 0.001) and 0.51 points at 4 weeks (p < 0.006) compared to the baseline scale. At the four-week follow-up, SSS remined improved at 0.47 points (p < 0.05). Symptoms of numbness/tingling improved at two and 4 weeks, as well as the follow-up (p < 0.05). Hand motor impairment such as weakness had a lower frequency across carpal tunnel syndrome sufferers and does not significantly improve (p > 0.05). Radioulnar wrist compression might be an effective alternative treatment in improving sensory related symptoms in patients with mild to moderate carpal tunnel syndrome.
• Li, Z., J, Z., Y, X., N, W., L, L., & K, L. (2022). Reach-to-grasp kinematics and kinetics in early-stage Alzheimer’s disease. https://doi.org/10.1186/s12984-022-01108-1. Journal of NeuroEngineering and Rehabilitation.
• Nadeem, M., Li, Z., & Seitz, W. (2021). Functional wrist kinematics during activities of daily living. Journal of Hand Surgery.
• Nadeem, M., Loss, J., Li, Z., & Seitz, W. (2022). Ulnar Extension Coupling in Functional Wrist Kinematics During Hand Activities of Daily Living. Journal of Hand Surgery, 47(2). doi:10.1016/j.jhsa.2021.03.026
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  Purpose: Wrist circumduction is increasingly used as a functional motion assessment for patients. Thus, increasing our understanding of its relation to the functional motion envelope is valuable. Previous studies have shown that the wrist is preferentially extended during hand activities of daily living (ADLs), with greater ulnar than radial deviation. The purpose of this study was to characterize the functional wrist motions of 22 modern ADLs in healthy subjects. We hypothesized that the subjects would perform ADLs predominantly in ulnar extension. Methods: Ten right-handed, healthy subjects performed flexion-extension, radioulnar deviation, maximal circumduction, and 22 modern ADLs. Angular wrist positions were obtained by tracking retroreflective markers on the hand and forearm. Angular motion data were analyzed with a custom program for peak/trough angles in flexion extension and radioulnar deviation, ellipse area of circumduction data, and ellipse area of combined motion data. Results: The required ranges of motion for ADLs were from 46.6° ± 16.5° of flexion (stirring task) to 63.8° ± 14.2° of extension (combing) in flexion-extension and from 15.6° ± 8.9° of radial deviation (opening a jar) to 32.5° ± 8.3° of ulnar deviation (picking up smartphone) in radioulnar deviation. Ellipse area of combined motion data of the 22 ADLs were, on average, 58.2% ± 14.3% of the ellipse area of maximal circumduction. A motion data quadrantal analysis revealed that 54.9% of all ADL wrist motion occurred in ulnar extension. Among the average wrist positions for 22 ADLs, 16 were located in the ulnar extension quadrant. Conclusions: This study revealed a functional wrist motion envelope that was less than 60% of wrist maximal motion capacity on average. Our results also showed that the majority of ADLs are performed in ulnar extension of the wrist. Clinical relevance: Baseline values for healthy subjects performing 22 wrist ADLs can inform future studies assessing dysfunction, postsurgical changes, and rehabilitation progress.
• Shah, R., & Li, Z. (2021). Three-dimensional carpal arch morphology using robot-assisted ultrasonography. Transactions on Biomedical Engineering.
• Shah, R., & Li, Z. (2022). Three-Dimensional Carpal Arch Morphology Using Robot-Assisted Ultrasonography. IEEE Transactions on Biomedical Engineering, 69(2). doi:10.1109/TBME.2021.3108720
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  Objective: The morphology of the carpal arch implicates the available space for the median nerve within the carpal tunnel. The purposes of this study were to 1) reconstruct the three-dimensional (3D) carpal arch by robot-assisted ultrasonography with a linear array transducer using cadaveric hands, and 2) investigate the 3D morphological properties of the carpal arch. Methods: An ultrasound probe with two-dimensional (2D) linear array was integrated on a robotic arm and maneuvered over the cadaveric carpal tunnels to scan the entire transverse carpal ligament and its osseous attachments to carpal bones. The acquired series of 2D ultrasound images together with robot positioning were utilized to reconstruct the 3D carpal arch for morphometric analyses. Results: Total carpal arch volume was 1099.4 ± 163.2 mm3 with the distal, middle, and proximal regions contributing 18.2 ± 1.5%, 32.7 ± 1.2%, and 49.1 ± 2.3%, respectively. The ligament surface area was 420.1 ± 63.9 mm2. The carpal arch width, height, curvature, length, area, and palmar bowing index progressively increased from the distal to proximal locations within the tunnel (p < 0.01). Conclusion: The incorporation of the robot technology with the ultrasound system advanced the applications of traditional 2D ultrasound imaging for a 3D carpal arch reconstruction, allowing for comprehensive morphological assessment of the carpal arch. Significance: The developed workflow can be used for the reconstruction and analysis of other anatomical features in vivo.
• Zhang, H., Loss, J., & Li, Z. (2021). Carpal arch changes in response to thenar muscle loading. Journal of Biomechanical Engineering.
• Lakshminarayanan, K., Shah, R., & Li, Z. M. (2020). Morphological and positional changes of the carpal arch and median nerve associated with wrist deviations. Clinical biomechanics (Bristol, Avon), 71, 133-138.
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  Carpal tunnel and median nerve dynamically change with wrist motion. The purpose of this study was to investigate the morphological changes and positional migration of the carpal arch and median nerve, as well as nerve-arch positional relationship associated with wrist deviation in healthy volunteers.
• Loss, J., & Li, Z. M. (2020). Biometry of thenar muscle origins on the flexor retinaculum. Clinical anatomy (New York, N.Y.), 33(8), 1176-1180.
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  The transverse carpal ligament (TCL), the main part of the flexor retinaculum, serves as an anchor for the thenar muscles: abductor pollicis brevis (APB), superficial head of the flexor pollicis brevis (sFPB), and opponens pollicis (OPP). Biomechanically, the thenar muscles rely on their TCL anchoring to transmit muscle contractions distally for thumb force and motion production, and reciprocally, muscle contraction interacts with the TCL at the proximal end through the origins. However, scarce knowledge exists regarding the distribution pattern of the thenar muscle origins. The purpose of this study was to understand the anatomical interface between the thenar muscles and TCL by examining the origin distributions of the individual muscles. Ten cadaveric specimens were dissected for digitization of the muscle origins and TCL volar surface. Digitized data were used for mesh reconstruction and calculation of surface areas and centroids. The origin areas for APB, sFPB, and OPP were 105.8 ± 30.3, 64.6 ± 15.2, and 245.9 ± 70.7 mm , respectively. The surface area of the TCL was 386.2 ± 86.9 mm . The origin areas of APB and OPP on the TCL were comparable, 18.4 ± 4.8% and 17.3 ± 9.6% of the TCL area, respectively. The origin locations for APB, sFPB, and OPP were in proximal-radial quadrant of the TCL, on distal aponeurosis outside the TCL, and around the ridge of trapezium, respectively. The knowledge of the anatomical interface provides a foundation for the understanding of biomechanical interactions between the muscles and ligaments and pathomechanical implications.
• Shah, R., & Li, Z. M. (2020). Ligament and Bone Arch Partition of the Carpal Tunnel by Three-Dimensional Ultrasonography. Journal of biomechanical engineering.
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  The carpal tunnel is structurally complex and geometrically irregular due to the many intercalated carpal bones by numerous intercarpal ligaments. The purpose of the study was to investigate the relative contributions of the ligament and bone arches to carpal tunnel space at the proximal, middle, and distal tunnel regions. A catheter ultrasound probe acquired fan-like images inside cadaveric carpal tunnels for three-dimensional reconstruction of the tunnel. The total tunnel volume was 5367.6 ± 940.1 mm3 with contributions of 12.0%, 6.9%, and 4.1% by proximal, middle, and distal ligament arches, respectively, and 27.0%, 25.3%, and 24.7% by proximal, middle, and distal bone arches, respectively. The bone arch occupied more tunnel space than the ligament arch at all regions (p
• Yao, Y., Grandy, E., Evans, P. J., Seitz, W. H., & Li, Z. M. (2020). Impairment of median nerve mobility in the segmental carpal tunnel of patients with carpal tunnel syndrome. Muscle & nerve, 62(4), 522-527.
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  The purpose of this study was to investigate in vivo median nerve longitudinal mobility in different segments of the carpal tunnel associated with active finger motion in carpal tunnel syndrome (CTS) patients in a comparison with healthy controls.
• Yao, Y., Grandy, E., Jenkins, L., Hou, J., Evans, P., Seitz, W., & Li, Z. (2019). Changes of median nerve conduction, cross-sectional area and mobility by radioulnar wrist compression intervention in patients with carpal tunnel syndrome. Journal of Orthopaedic Translation, 18. doi:10.1016/j.jot.2019.01.002
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  Background: Owing to the compressive nature of the neuropathy, patients with carpal tunnel syndrome (CTS) have prolonged distal motor latency (DML), sensory nerve latency (SNL), median nerve swelling and restricted median nerve mobility. The purpose of this study was to noninvasively augment carpal tunnel space using radioulnar wrist compression (RWC) and evaluate its effects on median nerve pathological properties in patients with CTS. It was hypothesized that the RWC intervention would reduce the median nerve DML, SNL and cross-sectional area (CSA) and enhance longitudinal median nerve mobility in patients. with CTS. Methods: Eleven patients diagnosed with CTS participated in this study. A portable RWC intervention splint was developed to apply 10 N of compressive force across the wrist. Three daily sessions of RWC were performed over 4 weeks of intervention (15 min per session, 45 min per day, 7 days per week). Each 15-min session consisted of three 5-min blocks of RWC, with a 1-min rest in between consecutive blocks. Patients were evaluated at Week 0 (baseline), Week 2 (mid-intervention) and Week 4 (end of intervention). DML and SNL of the median nerve were evaluated using established nerve conduction study techniques. Median nerve CSA at the distal wrist crease was obtained by ultrasound imaging. Median nerve motion associated with finger flexion/extension was captured by dynamic ultrasound imaging and quantified using a speckle cross-correlation algorithm. Finger flexion/extension was recorded using an electrogoniometer. The slope of the regressed linear equation of median nerve displacement as a function of finger flexion angle was used to quantify nerve mobility. Results: Patients with CTS showed significantly decreased DML (p = 0.048) and median nerve CSA (p < 0.001) and increased nerve mobility (p < 0.001) at mid-intervention compared to baseline. However, DML, CSA and mobility of the median nerve did not differ significantly between Weeks 2 and 4 (p = 0.574, 1.00 and 0.139, respectively). Median nerve SNL was not significantly affected throughout the 4-week intervention (p = 0.330 for Week 0 vs. 2; p = 1.00 for Week 2 vs. 4). Conclusion: This study revealed that RWC intervention with 10-N force applied to the wrist in the radioulnar direction could restore impaired neurophysiological and biomechanical functions of the median nerve. The beneficial effects of RWC intervention for the median nerve were in evidence after a relatively short period of two weeks. These functional improvements could be explained by intermittent decompression of the median nerve via RWC-induced augmentation of the carpal arch. The translational potential of this article: Biomechanically manipulating the carpal tunnel by RWC decompresses the median nerve and has the potential to become an alternative treatment for CTS.
• Grandy, E., Xiu, K., Marquardt, T., Li, C., Evans, P., & Li, Z. (2018). Carpal tunnel syndrome impairs index finger responses to unpredictable perturbations. Journal of Electromyography and Kinesiology, 38. doi:10.1016/j.jelekin.2017.03.001
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  The fine-tuning of digit forces to object properties can be disrupted by carpal tunnel syndrome (CTS). CTS’ effects on hand function have mainly been investigated using predictable manipulation tasks; however, unpredictable perturbations are commonly encountered during manual tasks, presenting situations which may be more challenging to CTS patients given their hand impairments. The purpose of this study was to investigate muscle and force responses of the index finger to unpredictable perturbations in patients with CTS. Nine CTS patients and nine asymptomatic controls were instructed to stop the movement of a sliding plate by increasing index finger force following an unexpected perturbation. The electrical activity of the first dorsal interosseous muscle and forces exerted by the index finger were recorded. CTS patients demonstrated 20.9% greater muscle response latency and 12.0% greater force response latency compared to controls (p < 0.05). The duration of plate sliding was significantly different between groups (p < 0.05); the CTS group's duration was 142.2 ± 5.8 ms compared to the control group's duration of 133.1 ± 8.4 ms. Although CTS patients had increased muscle and force response durations comparatively, these differences were not statistically significant. Findings from this study suggest CTS-induced sensorimotor deficits interfere with accurate detection, processing and response to unpredictable perturbations. These deficits could be accounted for at multiple levels of the peripheral and central nervous systems. Delayed and decreased responses may indicate inefficient object manipulation by CTS patients and may help to explain why CTS patients tend to drop objects.
• Yao, Y., Erdemir, A., & Li, Z. (2018). Finite element analysis for transverse carpal ligament tensile strain and carpal arch area. Journal of Biomechanics, 73. doi:10.1016/j.jbiomech.2018.04.005
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  Mechanics of carpal tunnel soft tissue, such as fat, muscle and transverse carpal ligament (TCL), around the median nerve may render the median nerve vulnerable to compression neuropathy. The purpose of this study was to understand the roles of carpal tunnel soft tissue mechanical properties and intratunnel pressure on the TCL tensile strain and carpal arch area (CAA) using finite element analysis (FEA). Manual segmentation of the thenar muscles, skin, fat, TCL, hamate bone, and trapezium bone in the transverse plane at distal carpal tunnel were obtained from B-mode ultrasound images of one cadaveric hand. Sensitivity analyses were conducted to examine the dependence of TCL tensile strain and CAA on TCL elastic modulus (0.125–10 MPa volar-dorsally; 1.375–110 MPa transversely), skin-fat and thenar muscle initial shear modulus (1.6–160 kPa for skin-fat; 0.425–42.5 kPa for muscle), and intratunnel pressure (60–480 mmHg). Predictions of TCL tensile strain under different intratunnel pressures were validated with the experimental data obtained on the same cadaveric hand. Results showed that skin, fat and muscles had little effect on the TCL tensile strain and CAA changes. However, TCL tensile strain and CAA increased with decreased elastic modulus of TCL and increased intratunnel pressure. The TCL tensile strain and CAA increased linearly with increased pressure while increased exponentially with decreased elastic modulus of TCL. Softening the TCL by decreasing the elastic modulus may be an alternative clinical approach to carpal tunnel expansion to accommodate elevated intratunnel pressure and alleviate median nerve compression neuropathy.
• Yao, Y., Grandy, E., Evans, P., Seitz, W., & Li, Z. (2018). Enhancement in median nerve mobility during radioulnar wrist compression in carpal tunnel syndrome patients. Clinical Biomechanics, 60. doi:10.1016/j.clinbiomech.2018.10.017
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  Background: Carpal tunnel syndrome is a compression neuropathy at the wrist associated with compromised median nerve mobility. The purpose of this study was to investigate the effects of radioulnar wrist compression on median nerve longitudinal mobility within the carpal tunnel in carpal tunnel syndrome patients as well as healthy subjects. Methods: Dynamic ultrasound images captured longitudinal median nerve motion in the carpal tunnel during radioulnar wrist compression force application in 11 healthy subjects and 11 carpal tunnel syndrome patients. Findings: We found that median nerve mobility was not significantly affected by radioulnar wrist compression in healthy subjects (P = 0.34), but improved by 10 N radioulnar wrist compression in carpal tunnel syndrome patients (P < 0.05). Analysis of segmental median nerve mobility in carpal tunnel syndrome patients showed significantly improved mobility in the proximal tunnel section under 10 N radioulnar wrist compression force condition compared to the no compression condition (P < 0.05). Interpretation: Moderate radioulnar wrist compression force application helps restore impaired median nerve mobility and may be effective in improve nerve function and symptoms associated with carpal tunnel syndrome.
• Li, K., Evans, P., Seitz, W., & Li, Z. (2015). Carpal tunnel syndrome impairs sustained precision pinch performance. Clinical Neurophysiology, 126(1). doi:10.1016/j.clinph.2014.05.004
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  Objective: The purpose of this study was to investigate effects of carpal tunnel syndrome (CTS) on digit force control during a sustained precision pinch. Methods: Eleven CTS individuals and 11 age- and gender-matched healthy volunteers participated in the study. The subjects were instructed to isometrically pinch an instrumented apparatus for 60. s with a stable force output. Visual feedback of force output was provided for the first 30. s but removed for the remaining 30. s. Pinch forces were examined for accuracy, variability, and inter-digit correlation. Results: CTS led to a decrease in force accuracy and an increase in amount of force variability, particularly without visual feedback (p< 0.001). However, CTS did not affect the structure of force variability or force correlation between digits (p > 0.05). The force of the thumb was less accurate and more variable than that of the index finger for both the CTS and healthy groups (p< 0.001). Conclusions: Sensorimotor deficits associated with CTS lead to inaccurate and unstable digit forces during sustained precision pinch. Significance: This study shed light on basic and pathophysiological mechanisms of fine motor control and aids in development of new strategies for diagnosis and evaluation of CTS.
• Nataraj, R., Evans, P., Seitz, W., & Li, Z. (2014). Effects of carpal tunnel syndrome on reach-to-pinch performance. PLoS ONE, 9(3). doi:10.1371/journal.pone.0092063
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  Background: Carpal tunnel syndrome (CTS) compromises fine sensorimotor function during activities of daily living. Reach-to-pinch for a small object requires not only dexterity of the grasping digits, but also coordinated transport of the hand to the target. This study examined the effects of CTS on the kinematic performance of reach-to-pinch maneuver. Methods: Eleven CTS subjects and 11 able-bodied (ABL) controls donned markers for motion capture of the hand, thumb and index finger during reach-to-pinch. Subjects were presented with a virtual target they could see without seeing their reaching upper-extremity. Subjects were instructed to reach to and grasp a virtual object as accurately and precisely as possible. Performance was assessed by variability of the movement trajectories of the digits and hand, the accuracy relative to the target, and precision of pinch contact over repetitive trials. Findings: The CTS group demonstrated significantly increased movement variability in inter-pad distance, joint angles, and transport of the hand compared to ABL controls (p
• Nataraj, R., Evans, P., Seitz, W., & Li, Z. (2014). Pathokinematics of precision pinch movement associated with carpal tunnel syndrome. Journal of Orthopaedic Research, 32(6). doi:10.1002/jor.22600
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  Carpal tunnel syndrome (CTS) can adversely affect fine motor control of the hand. Precision pinch between the thumb and index finger requires coordinated movements of these digits for reliable task performance. We examined the impairment upon precision pinch function affected by CTS during digit movement and digit contact. Eleven CTS subjects and 11 able-bodied (ABL) controls donned markers for motion capture of the thumb and index finger during precision pinch movement (PPM). Subjects were instructed to repetitively execute the PPM task, and performance was assessed by range of movement, variability of the movement trajectory, and precision of digit contact. The CTS group demonstrated shorter path-length of digit endpoints and greater variability in inter-pad distance and most joint angles across the PPM movement. Subjects with CTS also showed lack of precision in contact points on the digit-pads and relative orientation of the digits at contact. Carpal tunnel syndrome impairs the ability to perform precision pinch across the movement and at digit-contact. The findings may serve to identify deficits in manual dexterity for functional evaluation of CTS. © 2014 Orthopaedic Research Society.
• Chandler, J., Stabile, K., Pfaeffle, H., Li, Z., Woo, S., & Tomaino, M. (2003). Anatomic parameters for planning of interosseous ligament reconstruction using computer-assisted techniques. Journal of Hand Surgery, 28(1). doi:10.1053/jhsu.2003.50033
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  Purpose: Longitudinal radioulnar dissociation may result when both interosseous ligament (IOL) disruption and radial head fracture occur. Although radial head salvage or arthroplasty and temporary distal radioulnar joint pinning constitute the standard treatment for this injury, IOL reconstruction has been proposed to restore more normal forearm axis mechanics. To help provide an anatomic basis for IOL reconstruction, the purpose of this study was to characterize the geometry of the central band of the IOL and simulated IOL reconstructions. Methods: Twenty forearms free of pathology were dissected to bone-IOL-bone and computed tomography scans were taken. Computer models of radius-IOL-ulna were created from the computed tomography CT images, and computer-aided design software was used to measure key parameters for IOL reconstruction and simulate anatomic IOL reconstructions. Results: The insertion site locations of the IOL central band along the radius and ulna from the wrist were 57 ± 3% and 34 ± 4% of bone length, respectively. The angle at which the IOL central band inserts with the ulna was 24 ± 4 degrees, which agrees with previously reported values. We found that the minimum graft length needed to anatomically span both cortices through tunnels was 112 ± 14 mm. Conclusions: These data will help to provide a basis for planning and performing IOL reconstruction in cases of longitudinal radioulnar dissociation. Copyright © 2003 by the American Society for Surgery of the Hand.

Presentations

• Alsafar, F., Shah, R., & Li, Z. (2021, February). Thenar and hypothenar muscular coverage on the transverse carpal ligament. Annual meeting of the Orthopedic Research Society (ORS), February 13-16, 2021, Virtual (Podium).
• Coleman, K., Li, V., Zhang, H., Kwoh, K., & Li, Z. (2022). Thumb Carpometacarpal Joint Laxity in Pre- and Post- Menopausal Women. 2022 Annual Meeting of Orthopaedic Research Society (ORS).
• Hawk, J., Zhang, H., Margolis, D., & Li, Z. (2022). In Situ Needle Insertion to the Transverse Carpal Ligament Using Robot-Assisted Ultrasound. 2022 Annual Meeting of Orthopaedic Research Society (ORS).
• Huo, J., Zhang, H., Li, Z., & Roveda, J. (2022). Segmentation of Transverse Carpal Ligament in Ultrasound Images Using Convolutional Neural Network. 2022 Annual Meeting of Orthopaedic Research Society (ORS).
• Jordan, D., & Li, Z. (2022). Cross-sectional Changes of the Distal Carpal Tunnel with Simulated Carpal Bone Rotation. 2022 Annual Meeting of Orthopaedic Research Society (ORS).
• Li, Z. (2022, June/Summer).

  Thumb Carpometacarpal Joint Laxity in Young and Postmenopausal Women

  . IFSSH, IFSHT & FESSH Combined Congress 6-10 June 2022. London, UK.
• Li, Z., & Zhang, H. (2021, Jun). Finite element analysis for carpal arch under varying thenar muscle force magnitudes and directions. Summer Biomechanics, Bioengineering and Biotransport Conference (Virtual). June 14-18, 2021.
• Shah, R., & Li, Z. (2021, February). Three-dimensional carpal arch morphological analysis using robot assisted ultrasonography.. Annual meeting of the Orthopedic Research Society (ORS), February 13-16, 2021, Virtual (Poster). Virtual.
• Tamimi, E., Hawk, J., Witte, R., & Li, Z. (2022). Tamimi E, Hawk J, Witte R Li ZM, Load-dependent shear wave elastography of the transverse carpal ligament. 2022 Annual Meeting of Orthopaedic Research Society (ORS).
• Zhang, H., & Li, Z. (2021, February). Effect of musculoligamentous junction location on biomechanical interaction between the thenar muscles and transverse carpal ligament — a finite element study.. Annual meeting of the Orthopedic Research Society (ORS), February 13-16, 2021, Virtual (Poster).
• Zhang, H., & Li, Z. (2022). In Vivo Examination of Thenar Muscle Origins on the Transverse Carpal Ligament by 3-D Ultrasound Reconstruction. 2022 Annual Meeting of Orthopaedic Research Society (ORS).

Poster Presentations

• Li, Z., Tamimi, E., Hawk, J., & Witte, R. (2022). Load-dependent shear wave elastography of the transverse carpal ligament, February 04-08, 2022, Tampa, FL [Poster]. Annual Meeting of Orthopaedic Research Society (ORS).