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Development of a System to Test Anterior Cruciate Ligament
Failure
Austin Bussard
Alexander Houriet
Sydney Leonard
Griffin Monaghan
Group 10
Department of Mechanical Engineering and Materials Science
Noncontact ACL injuries are very common and have far reaching consequences for athletes.
150,000 ACL injuries occur annually in the US with recovery times for athletes exceeding nine months.
Among these injuries, roughly 70% were noncontact. [1]
Department of Mechanical Engineering and Materials Science
Bone
Department of Mechanical Engineering and Materials Science
Ligaments
Medial Collateral Ligament (MCL)
Posterior Cruciate Ligament (PCL)
Lateral Collateral Ligament (LCL)
Anterior Cruciate Ligament (ACL)
Department of Mechanical Engineering and Materials Science
Muscle
Department of Mechanical Engineering and Materials Science
Tendons
Department of Mechanical Engineering and Materials Science
The knee is comprised of four structures…
Bone• Purpose: Provides structural support to the leg• Specific parts: Femur, tibia, patella, fibula• Comprised of: Dense connective tissue
Ligaments• Purpose: Prevent excess motion of tibia relative to
femur• Specific parts: ACL, PCL, MCL, LCL• Comprised of: Fibrous connective tissue
Muscle• Purpose: Create forces required to move the leg• Specific parts: Quadriceps and hamstrings• Comprised of: Skeletal tissue
Tendons• Purpose: Direct tensile muscle forces to bones• Specific parts: Quadriceps tendon, patellar
tendon, and hamstring tendons• Comprised of: Fibrous connective tissue
Department of Mechanical Engineering and Materials Science
Given the significant
number of ACL injuries in the United States,
research must be done to
determine what causes ACL
injuries.
Department of Mechanical Engineering and Materials Science
Long Term Objective
Design a mechanical device to reproduce the jump landing ACL injury mechanism in cadaver knees in a
clinically significant manner.
Department of Mechanical Engineering and Materials Science
Project Background
Department of Mechanical Engineering and Materials Science
The ACL injury loading case is quite complex, making it difficult to determine exactly what is happening.
Department of Mechanical Engineering and Materials Science
Visualizing the “Jump Landing”
Injury Mechanism
Axial Compression
Anterior Tibial Shear
Valgus Rotation
Knee Flexion
Internal Tibial Rotation
Department of Mechanical Engineering and Materials Science
Group 10 Objective
Simulate muscle loads in the quadriceps and hamstring muscles of cadaver specimens.
Department of Mechanical Engineering and Materials Science
A cable-pulley system was used along with
pneumatic actuators to create and direct
muscle loads.
Department of Mechanical Engineering and Materials Science
Technical Requirements and Specifications
#1: Design a pneumatic system to create tensile muscle forces
#2: Design a pulley system to direct tensile muscle forces
#3: Adjustability in pulley position and orientation
Department of Mechanical Engineering and Materials Science
Bone• Purpose: Provides structural support to the leg• Specific parts: Femur, tibia, patella, fibula• Comprised of: Dense connective tissue
Ligaments• Purpose: Prevent excess motion of tibia relative to
femur• Specific parts: ACL, PCL, MCL, LCL• Comprised of: Fibrous connective tissue
Muscle• Purpose: Create forces required to move the leg• Specific parts: Quadriceps and hamstrings• Comprised of: Skeletal tissue
Tendons• Purpose: Direct tensile muscle forces to bones• Specific parts: Quadriceps tendon, patellar
tendon, and hamstring tendons• Comprised of: Fibrous connective tissue
Requirement #1: Design a pneumatic system to create tensile muscle forces
Department of Mechanical Engineering and Materials Science
Pneumatic Cylinders
Hamstrings Quadriceps
Department of Mechanical Engineering and Materials Science
Bone• Purpose: Provides structural support to the leg• Specific parts: Femur, tibia, patella, fibula• Comprised of: Dense connective tissue
Ligaments• Purpose: Prevent excess motion of tibia relative to
femur• Specific parts: ACL, PCL, MCL, LCL• Comprised of: Fibrous connective tissue
Muscle• Purpose: Create forces required to move the leg• Specific parts: Quadriceps and hamstrings• Comprised of: Skeletal tissue
Tendons• Purpose: Direct tensile muscle forces to bones• Specific parts: Quadriceps tendon, patellar
tendon, and hamstring tendons• Comprised of: Fibrous connective tissue
Requirement #2: Design a cable-pulley system to direct tensile muscle forces
Department of Mechanical Engineering and Materials Science
Design 1
Cable Pulley Design Choice
Design 2 Design 3
Department of Mechanical Engineering and Materials Science
Design Adaptation: Alteration of Actuator-Cable Attachment
Department of Mechanical Engineering and Materials Science
Requirement #3: Adjustability
Pulley position and orientation
Hamstring and quadricep loading
ratios
Department of Mechanical Engineering and Materials Science
Adjustability in Pulley Position
Department of Mechanical Engineering and Materials Science
Adjustability in Pulley
Orientation
Department of Mechanical Engineering and Materials Science
Adjustability in Hamstring and Quadriceps Loading Ratios
If, 𝑀𝑎𝑥𝑖𝑚𝑢𝑚 𝐻𝑎𝑚𝑠𝑡𝑟𝑖𝑛𝑔 𝑇𝑒𝑛𝑠𝑖𝑙𝑒 𝐿𝑜𝑎𝑑
𝑀𝑎𝑥𝑖𝑚𝑢𝑚 𝑄𝑢𝑎𝑑𝑟𝑖𝑐𝑒𝑝 𝑇𝑒𝑛𝑠𝑖𝑙𝑒 𝐿𝑜𝑎𝑑< 0.6, ACL injury probability increases.
Hamstrings Quadriceps
Department of Mechanical Engineering and Materials Science
Final Product
Department of Mechanical Engineering and Materials Science
Final Product
Department of Mechanical Engineering and Materials Science
Ability to compare effectiveness of ACL
reconstruction procedures
Research into how different factors
affect predisposition to ACL injuries
Development of non-surgical injury
prevention techniques
Potential Benefits of Project Success
Department of Mechanical Engineering and Materials Science
Acknowledgements
• Dr. Smolinski
• Dr. Szabo
• Dr. Schmidt
• Jeff Speakman
• Andy Holmes
Department of Mechanical Engineering and Materials Science
[1] - Boden, BP , Dean, GS , Feagin, JA , Garrett, WE Mechanisms of anterior cruciate ligament injury. Orthopedics. 2000;23:573–578.
[2] - Bates, NA, Schilaty, ND, Nagelli, CV, Krych, AJ, Hewett, TE. Novel mechanical impact simulator designed to generate clinically relevant anterior cruciate ligament ruptures. Clin Biomech (Bristol, Avon). 2017;44:36-44.
Department of Mechanical Engineering and Materials Science
Appendix
The hamstrings contract to flex the knee while quadriceps contract to straighten the knee.
Department of Mechanical Engineering and Materials Science
Past group contributions
● Aluminum frame
● Rail that supports femoral mount
● Femoral mount
● Machining of McMaster-Carr pulleys
● Mounting of two cylinders
Department of Mechanical Engineering and Materials Science
Actuator Pressure Determination
Department of Mechanical Engineering and Materials Science
Bill of MaterialsItem Name Description Quantity Vendor Part Number Price Per Unit Total Price
Round Body Air Cylinder Double-Acting, Universal Mount, 2" Bore, 12" Stroke Length 1 McMaster-Carr 6498K568 $125.93 $125.93
Steel U-Bolt 3/8"-16 Threads, 2-1/2" ID 4 McMaster-Carr 8880T91 $2.65 $10.60
Mounted Pulley Mounted, for 1/4" wire, 3' OD 1 McMaster-Carr 3099T38 $13.16 $13.16
Pressure Regulator 5-100 PSI outlet range, 1/4" NPT ports 1 McMaster-Carr 9891K43 $63.55 $63.55
Small Coupling Nut 1 3/4" long, 7/16-20 thread 2 McMaster-Carr 90977A190 $5.09 $10.18
Big Coupling Nut 1 3/4" long, 1/2-20 thread 1 McMaster-Carr 90977A034 $5.59 $5.59
Small Eye Bolt 7/16-20 thread 1 3/8" shank 2 McMaster-Carr 3013T961 $9.03 $18.06
Big Eye Bolt 1/2-20 thread 1 3/8" shank 1 McMaster-Carr 3013T344 $4.42 $4.42
Pressure Relief Valve 100 psi set pressure fast release valve, 1/4" NPT Port 4 McMaster-Carr 48435K72 $5.41 $21.64
Pressure Relief Valve 100 psi set pressure fast release valve 1/8" NPT Port 1 McMaster-Carr 48435K82 $16.61 $16.61
Hose Adapter for Large cylinder 3/8" NPT threading to 1/4" hose 1 McMaster-Carr 5350K33 $2.14 $2.14
Hose Adapter for Large cylinder 1/4" NPT threading to 1/4" hose 1 McMaster-Carr 5350K32 $2.01 $2.01
Hose Clamps 7/32" to 5/8" worm hose clamp 1 McMaster-Carr 5388K14 $6.26 $6.26
Hex Screws 1/4"-20 threaded, 1.5" length 3/8 hex drive screws 1 McMaster-Carr 90044A123 $13.25 $13.25
Compressor fitting 1/4" NPTF to 1/4" barb adaptor 1 McMaster Carr 5346K42 $15.94 $15.94
Compressor to Regulator connector 1/4" barb T Connector 1 McMaster Carr 91355K47 $6.55 $6.55
Total Cost: $335.89
Department of Mechanical Engineering and Materials Science
L-Beam Static Structural Simulation
Beam #1
(Hamstring
Actuators)
Beam #2
(Quadricep
Actuator)
Department of Mechanical Engineering and Materials Science
L-Beam Static Structural Simulation (cont.)
o Fixed supports at mounting bolt holes
o 450 N load distributed about the area where the actuator comes in contact with the beam
o Max Deformation: 0.887 mm
o Max Equivalent Stress: 6.03 MPa
o Yield Stress: 28 MPa (FOS = 4.64)
Total Deformation
Equivalent (von-Mises Stress)
Department of Mechanical Engineering and Materials Science
L-Beam Static Structural Simulation (cont.)
o Fixed supports at mounting bolt holes
o 225 N load distributed about the area where the two actuators comes in contact with the beam with the hole drilled by previous group in the center
o Max Deformation: 0.887 mm
o Max Equivalent Stress: 12 MPa
o Yield Stress: 28 MPa (FOS = 2.33)
Total Deformation
Equivalent (von-Mises Stress)
Department of Mechanical Engineering and Materials Science
Pulley Strength Validation
Maximum allowable load (from vendor) = 200 lbf
FOS = 1.4
Department of Mechanical Engineering and Materials Science
Cable Strength Validation
Maximum allowable load (from vendor) = 340 lbf
FOS = 3.36
Department of Mechanical Engineering and Materials Science
The ratio of hamstring to quadricep muscle loads have a significant effect on ACL injury predisposition. [1]
The hamstrings and quadriceps stabilize the knee during an imbalance reaction, for example a jump landing. As the tibia tries to translate forward or backwards because of the instability, the hamstrings and quadriceps impart a restoring force to keep the bone in place. But if the hamstrings are far weaker than the quadriceps the net force acting on the tibia will place the ACL in tension. If the imbalance in strength is large, the ACL is more likely to fail.
Department of Mechanical Engineering and Materials Science
Criteria Weight Baseline Design 1 Design 2 Design 3
Correct Lines of action 5 0 - + +
Position Adaptability 3 0 - 0 +
Cost 1 0 0 0 -
Ease of Implementation 2 0 + - -
Simplicity 1 0 ++ + -
Sustainability (e.g. maintenance needs) 1 0 + + -
Total 0 -3 5 3