development of a system to test anterior cruciate ligament ...ach75/acl_presentation.pdf ·...

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]


Bone


Ligaments

Medial Collateral Ligament (MCL)

Posterior Cruciate Ligament (PCL)

Lateral Collateral Ligament (LCL)

Anterior Cruciate Ligament (ACL)


Muscle


Tendons


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


Given the significant

number of ACL injuries in the United States,

research must be done to

determine what causes ACL

injuries.


Long Term Objective

Design a mechanical device to reproduce the jump landing ACL injury mechanism in cadaver knees in a

clinically significant manner.


Project Background


The ACL injury loading case is quite complex, making it difficult to determine exactly what is happening.


Visualizing the “Jump Landing”

Injury Mechanism

Axial Compression

Anterior Tibial Shear

Valgus Rotation

Knee Flexion

Internal Tibial Rotation


Group 10 Objective

Simulate muscle loads in the quadriceps and hamstring muscles of cadaver specimens.


A cable-pulley system was used along with

pneumatic actuators to create and direct

muscle loads.


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








Requirement #1: Design a pneumatic system to create tensile muscle forces


Pneumatic Cylinders

Hamstrings Quadriceps








Requirement #2: Design a cable-pulley system to direct tensile muscle forces


Design 1

Cable Pulley Design Choice

Design 2 Design 3


Design Adaptation: Alteration of Actuator-Cable Attachment


Requirement #3: Adjustability

Pulley position and orientation

Hamstring and quadricep loading

ratios


Adjustability in Pulley Position


Adjustability in Pulley

Orientation


Adjustability in Hamstring and Quadriceps Loading Ratios

If, 𝑀𝑎𝑥𝑖𝑚𝑢𝑚 𝐻𝑎𝑚𝑠𝑡𝑟𝑖𝑛𝑔 𝑇𝑒𝑛𝑠𝑖𝑙𝑒 𝐿𝑜𝑎𝑑

𝑀𝑎𝑥𝑖𝑚𝑢𝑚 𝑄𝑢𝑎𝑑𝑟𝑖𝑐𝑒𝑝 𝑇𝑒𝑛𝑠𝑖𝑙𝑒 𝐿𝑜𝑎𝑑< 0.6, ACL injury probability increases.

Hamstrings Quadriceps


Final Product


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


Acknowledgements

• Dr. Smolinski

• Dr. Szabo

• Dr. Schmidt

• Jeff Speakman

• Andy Holmes


[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.


Appendix

The hamstrings contract to flex the knee while quadriceps contract to straighten the knee.


Past group contributions

● Aluminum frame

● Rail that supports femoral mount

● Femoral mount

● Machining of McMaster-Carr pulleys

● Mounting of two cylinders


Actuator Pressure Determination


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


L-Beam Static Structural Simulation

Beam #1

(Hamstring

Actuators)

Beam #2

(Quadricep

Actuator)


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)


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)


Pulley Strength Validation

Maximum allowable load (from vendor) = 200 lbf

FOS = 1.4


Cable Strength Validation

Maximum allowable load (from vendor) = 340 lbf

FOS = 3.36


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.


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

development of a system to test anterior cruciate ligament ...ach75/acl_presentation.pdf ·...

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