Abstract Hamstring injuries are one of the most common muscle maladies in athletes, especially in runners. Injury usually occurs late in swing phase when the hamstring is in eccentric contraction and needs to change the direction of the leg rapidly. Re-injury is very common after recovery from these injuries, so it is necessary to tailor rehabilitation programs to improve biomechanical function after healing. Most current imaging techniques that are used to assess this function can only do so under static conditions, thus they cannot provide direct measurements of muscle velocity under simulated load. We have developed a device that will load the leg at a percentage of a subject's maximum voluntary contraction via inertia through extension of the knee. Most of the semester was spent developing equations of motion that define our system and performing a free body analysis on our design to be sure that our inertial load was feasible for us to construct. The final prototype consists of the subject lying prone on the base of the device with the ankle attached to a plastic chain that turns three sprockets. The other end of the chain is connected to the counterweight that supports the weight of the shank and for each turn of the sprockets, the disks provide a rotational inertial load to the hamstring during extension. This device will be tested in the motion lab over the next few weeks to capture the motion of the shank and test the accuracy of the motion. Subsequently, the device will be used in conjunction with CINE-Phase Contrast MRI to determine muscle velocity of the injured hamstring. Any further modifications to the prototype will be determined after testing is complete.

Problem Statement Most current imaging techniques are static Require the use of a non-magnetic device Use Cine-PC (Phase contrast) imaging measure in-vivo musculotendon motion during a stretch-shortening cycle Requires multiple cycles of motion Repeatable motion at low loads

Motivation Measure velocity of muscle fibers around scar tissue Prevent re-injury Tailor rehabilitation programs Thelen Group

Muscle Anatomy/Injury 3 separate muscles Pulled hamstring Eccentric contraction Scar tissue formation Affects muscle performance Re-injury is common Human Locomotion Research Center, UCLA

Gait Cycle Interested in swing phase Eccentric contraction of hamstring at late swing phase Muscle must change leg direction Loudon, J.K. Biomechanics of Gait and Running

Summary of Current Devices 12 different devices in literature Subjects lay supine/prone in device Between 0 – 90 degrees flexion Weight attached to pulley Cons Motion not restricted Non-physiological load Patient fatigue Non-periodic motion Patel, V.V. Journal of Orthopedic Research

Design Constraints Provide repeatable, harmonic motion Same start/end points – bore size Generate physiological load on hamstring Simulate swing phase of running Support thigh – limit movement Non-metallic, non-ferrous materials

Loading Systems

Loading Systems

Loading Systems

Equations of Motion Angle θo 2θo Time (s) 0.5 1.0 1.5 2.0

Free Body Analysis

Free Body Analysis = Conservation of Energy Constraints

Final Design

Manufacturing Mill Lathe Drill press Band saw Sander

Materials and Costs

Future Work Motion capture lab Modify prototype Validation in MRI Determine accuracy of motion Modify prototype Reduce bulkiness Validation in MRI Obtain data from subjects

References 1. Asakawa DS, Nayak KS, Blemker SS, Delp SL, Pauly JM, Nishimura DG, Gold GE. Real-time imaging of skeletal muscle velocity. Journal of Magnetic Resonance Imaging. 2003; 18:734-739. 2. Asakawa DS, Pappas GP, Blemker SS, Dracce JE, Delp SL. Cine phase-contrast magnetic resonance imaging as a tool for quantification of skeletal muscle motion. Seminars in Musculoskeletal Radiology. 2003; 7(4):287-295. 3. Asakawa DS, Blemker SS, Gold BE, Delp SL. In vivo motion of the rectus femoris muscle after tendon transfer surery. Journal of Biomechanics. 2002; 35(8):1029-1037. 4. Asakawa DS, Pappas GP, Blemker SS, Drace JE, Delp SL. Cine phase-contrast magnetic resonance imaging as a tool for quantification of skeletal muscle motion. Seminars in Musculoskeletal Radiology. 2003; 7(4): 287-295. 5. Barance PJ, Williams GN, Novotny JE, Buchanan TS. A method for measurement of joint kinematics of 3-D geometric models with cine phase contrast magnetic resonance imaging data. Journal of Biomechanical engineering. 2005; 127:829-837. 6. Barrancce P, Williams G, Sheehan FT, Buchanan TS. Measurement of tibiofemoral joint motion using CINE-Phase Contrast MRI. 7. Barrancce P, Williams G, Sheehan FT, Buchanan TS. Measurement of tibiofemoral joint motion using CINE-Phase Contrast MRI. 8. Fellows RA, Hill NA, MacIntyre NJ, Harrison MM, Ellis RE, Wilson DR. Repeatability of a novel technique for in vivo measurement of three-dimensional patellar tracking using magnetic resonance imaging. Journal of Magnetic Resonance Imaging. 2005; 22: 145-153. 9. Komi PV. Stretch-shortening cycle: a powerful model to study normal and fatigued muscle. Journal of Biomechanics. 2000; 33:1197-1206. 10. Neu CP, Hull ML. Toward an MRI-based method to measure non-uniform cartilate deformation: an MRI-cyclic loading apparatus system and steady-state cyclic displacement of articular cartilage under compressive loading. Journal of Biomechanical Engineering. 2003; 125(2):180-188. 11. Pappas GP, Asakawa DS, Delp SL, Zajac FE, Drace JE. Nonuniform shortening in the biceps brachii during elbow flexion. Journal of Applied Physiology. 2002; 92:2381-2389. 12. Patel VV, Hall K, Ries M, Lotz J, Ozhinsky E, Lindsey C, Lu Y, Majumdar S. A three-dimensional MRI analysis of knee kinematics. Journal of Orthopedic Research. 2004; 22:283-292. 13. Patel VV, Hall K, Ries M, Lindsey C, Ozhinsky E, Lu Y, Majumdar S. Magnetic resonance imaging of patellofemoral kinematics with weight-bearing. Journal of Bone and Joint Surgery. 2003; 85:2419-2424. 14. Patel VV, Hall K, Ries M, Lindsey C, Ozhinsky E, Lu Y, Majumdar S. Magnetic resonance imaging of patellofemoral kinematics with weight-bearing. Journal of Bone and Joint Surgery. 2003; 85:2419-2424. 15. Rebmann AJ, Rausch T, Shibanuma N, Sheehan FT. The precision of CINE-PC and Fast-PC sequences in measuring skeletal kinematics. Proc. Intl. Soc. Mag. Reson. Med. 2001; 9: 83. 16. Rebmann AJ, Sheehan FT. Precise 3D skeletal kinematics using fast phase contrast magnetic resonance imaging. Journal of Magnetic Resonance Imaging. 2003; 17: 206-213. 17. Sheehan FT, Drace JE. Quantitative MR measures if three-dimensional patellar kinematics as a research and diagnostic tool. Medicine and Science in Sports and Exercise. 1999; 31(10): 1339-??. 18. Sheehan F, Zejac FE, Drace J. Imaging musculoskeletal function using dynamic MRI. Rehabilitation R&D Center Progress Report. 1996. 19. Thelen DG, Chumanov ES, Sherry MA, Heiderscheit BC. Neuromusculoskeletal models provice insights intot he mechanisms and rehabilitation of hamstring strains. Exercise and Sports Science Reviews. 2006; 34(3): 135-141. 20. Vedi V, Williams A, Tennant SJ, Spouse E, Hunt DM, Gedroyc WMW. Meniscal movement: an in vivo study using dynamic MRI. British Editorial Society of Bone and Joint Surgery. 1999; 81-B(1):37-41.

Acknowledgements William Murphy Darryl Thelen Amy Silder Larry Wheeler Wally Block Kelly Hellenbrand Physical Plant McMaster Carr