1. 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.

2. 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

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

4. 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

5. 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

6. 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

7. 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

8. Loading Systems

9. Loading Systems

10. Loading Systems

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

12. Free Body Analysis

13. Free Body Analysis =
Conservation of Energy
Constraints

14. Final Design

15. Manufacturing
Mill
Lathe
Drill press
Band saw
Sander

16. Materials and Costs

17. 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

18. 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:
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):
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):
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):
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:
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:
9. Komi PV. Stretch-shortening cycle: a powerful model to study normal and fatigued muscle. Journal of Biomechanics. 2000; 33:
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):
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:
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:
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:
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:
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:
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
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 ; 34(3):
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.

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