• Specifications
• ExperimentationTissueMechanics

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TableOfContents

Target Outcome

Material behavior for all primary and secondary tissues necessary for required representative constitutive models.

Prerequisites

Infrastructure

For more details see ["Infrastructure/ExperimentationMechanics"].

Previous Protocols

For more details see ["Specifications/Specimens"].

For more details see ["Specifications/ExperimentationAnatomicalImaging"]

For more details see ["Specifications/Registration"].

For more details see ["Specifications/SpecimenPreparation"].

For more details see ["Specifications/ExperimentationJointMechanics"]

Tissue types

Primary tissues

Cartilage

1. Medial femoral condyle
2. Lateral femoral condyle
3. Medial tibial plateau
4. Lateral tibial plateau
5. Patellar groove / femoral groove
6. Patella

Meniscus

1. Medial meniscus
2. Lateral meniscus

Ligaments

1. Anterior collateral ligament
2. Posterior collateral ligament
3. Lateral collateral ligament
4. Medial collateral ligament
5. Patellar ligament

Tendon

1. Quadriceps tendon

Secondary tissues

Capsule

1. TBD

Protocols

Ligaments

Conditions

• Uniaxial tension
  • Preload: 0.1 N (OR pre-stress value: TBD)
  • Wait: 10 min
  • Preconditioning: amplitude: 0.5% strain, 10 cycles
  • 10 preconditioning cycles are applied at 0.25 mm amplitude.

-- ["bonnert2"] DateTime(2014-07-01T13:09:49Z) What is the rate of the preconditioning cycles? Are we doing two preconditions; 10 cycles at 0.5% strain AND 10 cycles and 0.25 mm amplitude? I assume the 0.25 mm IS 0.5% strain for the dogbone press we are using but it is not super clear.

• Stress relaxation: 2.5%, 5%, 7.5% and 10% strain at 20%/s (OR 100%/s, TBD)
• Hold time after each strain application will be 60 min OR a rate change criterion will be set.

Measurements

• Force-deformation behaviour

Operating Procedure

• Once the ligaments are separated for tissue testing sample preparation, the thicker ligaments (ACL, PCL, MCL and LCL) will be thinned for tensile testing. This is done using a cryostat (Available at Histochemistry Core at Biomedical Engineering, CCF). The ligaments will be thinned to be under 1 mm.
• Once the thin segments are obtained, using a dummbell shaped punch, tensile testing samples will be prepared.
• The punch is 10 mm by 2mm between the flared sections used for clamping the tissue.
• MCL is thin enough to be punched without any further thinning.
• Samples will be taken from the mid-substance region of the ligaments and along the long axis of the fibers. attachment:mcl-sample.png Sample MCL
• Once the samples are punched out, the thickness of the samples will be measured.
• Decision is still pending on whether the thickness will be measured optically or using a constant-pressure (~0.001 MPa) linear variable displacement transducer (LVDT) probe.
• It is recommended that the load cell be calibrated before each test.
• The sample will be placed in serrated metal clamps for mounting in the tissue testing machine.
• Sand paper and tissue adhesive will be used along with the metal clamps to prevent the test samples from slipping during the mechanical tests.
• Tests will be conducted on MA056-V500c material testing machine (Biomomentum Inc, Laval, Québec, Canada). attachment:mach1.png

-- ["bonnert2"] DateTime(2014-07-01T13:09:49Z) A lot of the stuff above seems more appropriate in "sample preparation." Maybe we could just put a link?

• Specimens will be kept immersed in a saline bath and kept at 37 °C during testing.
• Stress relaxation tests will be conducted on each sample. The protocols with entire sequences are programmed in the system and can be repeated with adjustments based on sample dimensions.
• For tensile tests the 'find contact' step is performed first to obtain the initial length of the sample (this is application of prestrain for the first time).
• Recommended: before running any test with longer hold times, the test should be run once with 2-3 sec hold time to ensure the procedure is working as expected.

Cartilage

Conditions

• Uniaxial tension
  • Preload: 0.05 N (OR pre-stress value: TBD) (to obtain the initial length)
  • Unload
  • Wait: 20 min
  • upload test sequence, adjust parameters based on intial length.
  • Preload: 0.05 N (OR pre-stress value: TBD)
  • Wait: 10 min
  • Preconditioning: amplitude: 1% strain, 10 cycles

-- ["bonnert2"] DateTime(2014-07-01T13:09:49Z) What's the rate for all preconditioning?

• Stress relaxation: 2.5%, 5%, 7.5%, 10%, 12.5% and 15% strain at 20%/s (OR 100%/s, TBD)
• Hold time after each strain application will be 45 min OR a rate change criterion will be set.
• Unload
• Video data will be recorded at 10Hz.
• Data acquisition frequency will be set to 100Hz.

• Confined compression
  • Preload: 0.05 N (OR pre-stress value: TBD)
  • Unload
  • Wait: 10 min
  • Preconditioning: amplitude: 1% strain, 10 cycles
  • Stress relaxation: 2.5%, 5%, 7.5%, 10%, 12.5% and 15% strain at 20%/s (OR 100%/s, TBD)
  • Hold time after each strain application will be 45 min OR a rate change criterion will be set.
• Unconfined compression
  • Preload: 0.05 N (OR pre-stress value: TBD)
  • Unload
  • Wait: 10 min
  • Preconditioning: amplitude: 1% strain, 10 cycles
  • Stress relaxation: 2.5%, 5%, 7.5%, 10%, 12.5% and 15% strain at 20%/s (OR 100%/s, TBD)
  • Hold time after each strain application will be 45 min OR a rate change criterion will be set.

-- ["bonnert2"] DateTime(2014-07-01T13:09:49Z) As a general rule, it might be a good idea to put the formulas for calculating strain for tension and compression(s). This can maybe be done at the top with an example. I know this is an easy thing to figure out, but it might help prevent mistakes. Maybe put it in the operating procedure?

Measurements

• Force-deformation behaviour

Operating Procedure

• Tensile test
  • once the tibia and femur articular surfaces are exposed after dissection, rectangular strips of cartilage will be separated from the bone using a scalpel.
  • Using a 5 mm by 1 mm punch tensile samples will be obtained.
  • A vibratome will be used to obtain thin uniform thickness samples (settings will be optimized and reported).
  • Once the samples are punched out, the thickness of the samples will be measured.
  • Decision is still pending on whether the thickness will be measured optically or using a constant-pressure (~0.001 MPa) linear variable displacement transducer (LVDT) probe.
  • Tests will be conducted on MA056-V500c material testing machine (Biomomentum Inc, Laval, Québec, Canada).
  • The sample will be placed in serrated tensile clamps (using tissue adhesive and sand paper) and the whole assembly will be fixed in a saline bath (in the testing system) and kept at 37 °C during testing.
  • Stress relaxation tests will be conducted on each sample.
• Confined compression
  • once the tibia and femur articular surfaces are exposed after dissection, rectangular strips of cartilage will separated from the bone using a scalpel.
  • A 5 mm diameter punch will be used to obtain cylindrical, full thickness cartilage samples.
  • A vibratome will be used to obtain uniform thickness samples (settings will be optimized and reported).
  • Once the samples are punched out and cut uniformly, the thickness of the samples will be measured.
  • Decision is still pending on whether the thickness will be measured optically or using a constant-pressure (~0.001 MPa) linear variable displacement transducer (LVDT) probe.
  • It is recommended that the load cell be calibrated before each test.
  • Tests will be conducted on MA056-V500c material testing machine (Biomomentum Inc, Laval, Québec, Canada).
  • The sample will be placed in a confined compression chamber and the whole assembly will be fixed in a saline bath and kept at 37 °C during testing.
  • A stainless steel filter will be placed on the sample and an indentor will be used to compress the sample while it is enclosed in the compression chamber.
  • Stress relaxation tests will be conducted on each sample.
• Unconfined compression
  • Samples used in confined compression will be allowed to rest (no load) and will be reused in unconfined compression tests.
  • The sample will be placed on a flat compression platform and the whole assembly will be fixed in a saline bath and kept at 37 °C during testing.
  • Stress relaxation tests will be conducted on each sample using a flat indentor.

Menisci

Conditions

• Uniaxial tension
  • Preload: 0.05 N (OR pre-stress value: TBD)
  • Wait: 10 min
  • Preconditioning: amplitude: 0.5% strain, 10 cycles

-- ["bonnert2"] DateTime(2014-07-01T13:09:49Z) What's the rate for all the preconditioning?

• Stress relaxation: 2.5%, 5%, 7.5%, 10%, 12.5% and 15% strain at 20%/s (OR 100%/s, TBD)
• Hold time after each strain application will be 45 min OR a rate change criterion will be set.

• Confined compression
  • Preload: 0.05 N (OR pre-stress value: TBD)
  • Wait: 10 min
  • Preconditioning: amplitude: 0.5% strain, 10 cycles
  • Stress relaxation: 2.5%, 5%, 7.5%, 10%, 12.5% and 15% strain at 20%/s (OR 100%/s, TBD)
  • Hold time after each strain application will be 45 min OR a rate change criterion will be set.
• Unconfined compression
  • Preload: 0.05 N (OR pre-stress value: TBD)
  • Wait: 10 min
  • Preconditioning: amplitude: 0.5% strain, 10 cycles
  • Stress relaxation: 2.5%, 5%, 7.5%, 10%, 12.5% and 15% strain at 20%/s (OR 100%/s, TBD)
  • Hold time after each strain application will be 45 min OR a rate change criterion will be set.

Measurements

• Force-deformation behaviour

Operating Procedure

• Tensile test
  • Each meniscus will be divided into three sections radially. The middle section will be selected so that it is just enough to accommodate the tensile punch (5 mm by 1 mm test length).
  • Thin strips will be obtained (depth wise) from the middle section and tensile sample will be punched from the circumference.
  • Once the samples are punched out, the thickness of the samples will be measured.
  • Decision is still pending on whether the thickness will be measured optically or using a constant-pressure (~0.001 MPa) linear variable displacement transducer (LVDT) probe.
  • It is recommended that the load cell be calibrated before each test.
  • Tests will be conducted on MA056-V500c material testing machine (Biomomentum Inc, Laval, Québec, Canada).
  • The sample will be placed in serrated tensile clamps (using tissue adhesive and sand paper) and the whole assembly will be fixed in a saline bath and kept at 37 °C during testing.
  • Stress relaxation tests will be conducted on each sample.
• Confined compression
  • 5 mm diameter samples will be punched from the anterior and posterior sections of the menisci and used in compression tests.

-- ["bonnert2"] DateTime(2014-07-01T13:09:49Z) picture would be nice here

• A vibratome will be used to obtain uniform thickness samples (settings will be optimized and reported).
• Once the samples are punched out and cut uniformly, the thickness of the samples will be measured.
• Decision is still pending on whether the thickness will be measured optically or using a constant-pressure (~0.001 MPa) linear variable displacement transducer (LVDT) probe.
• It is recommended that the load cell be calibrated before each test.
• Tests will be conducted on MA056-V500c material testing machine (Biomomentum Inc, Laval, Québec, Canada).
• The sample will be placed in a confined compression chamber and the whole assembly will be fixed in a saline bath and kept at 37 °C during testing.
• A stainless steel filter will be placed on the sample and an indentor will be used to compress the sample while it is enclosed in the compression chamber.
• Stress relaxation tests will be conducted on each sample.

• Unconfined compression
  • Samples used in confined compression will be allowed to rest (no load) and will be reused in unconfined compression tests.
  • The sample will be placed on a flat compression platform and the whole assembly will be fixed in a saline bath and kept at 37 °C during testing.
  • Stress relaxation tests will be conducted on each sample using a flat indentor.

Tendons

Conditions

• Uniaxial tension
  • Preload: 0.1 N (OR pre-stress value: TBD)
  • Wait: 10 min
  • Preconditioning: amplitude: 0.5% strain, 10 cycles

-- ["bonnert2"] DateTime(2014-07-01T13:09:49Z) preconditioning rate? Again, confusing with the 0.5% strain and 0.25 mm

• 10 preconditioning cycles will be applied at 0.25 mm amplitude.
• Stress relaxation: 2.5%, 5%, 7.5% and 10% strain at 20%/s (OR 100%/s, TBD)
• Hold time after each strain application will be 60 min OR a rate change criterion will be set.

Measurements

• Force-deformation behaviour

Operating Procedure

• Once the tendon is separated for tissue testing sample preparation, it will be thinned for tensile test. This is done using a cryostat (Available at Histochemistry Core at Biomedical Engineering, CCF). The tendon will be thinned to be under 1 mm.
• Once the thin segments are obtained, using a dummbell shaped punch, tensile testing samples will be prepared.
• The punch is 10 mm by 2mm between the flared sections used for clamping the tissue.
• Once the samples are punched out, the thickness of the samples will be measured.
• Decision is still pending on whether the thickness will be measured optically or using a constant-pressure (~0.001 MPa) linear variable displacement transducer (LVDT) probe.
• The sample will be placed in serrated metal clamps for mounting in the tissue testing machine.
• Sand paper and tissue adhesive will be used along with the metal clamps to prevent the test samples from slipping during the mechanical tests.
• Tests will be conducted on MA056-V500c material testing machine (Biomomentum Inc, Laval, Québec, Canada).
• Specimens will be kept immersed in a saline bath and kept at 37 °C during testing.
• Stress relaxation tests will be conducted on each sample.

Capsule

Conditions

Measurements

• Force-deformation behaviour

Operating Procedure

References

1. Seitz, Andreas Martin, Fabio Galbusera, Carina Krais, Anita Ignatius, and Lutz Dürselen. “Stress-relaxation Response of Human Menisci Under Confined Compression Conditions.” Journal of the Mechanical Behavior of Biomedical Materials 26 (October 2013): 68–80. doi:10.1016/j.jmbbm.2013.05.027. http://www.sciencedirect.com/science/article/pii/S175161611300204X

---

-- ["aerdemir"] DateTime(2013-10-15T13:42:41Z) I provided an outline above to help categorize activities.

-- ["aerdemir"] DateTime(2013-10-15T13:42:41Z) Should sample descriptions go to "Specifications/Specimens"? Ideally tissue-specific operating procedure should be followed for any given sample from that tissue.

Data acquisition by Elvis Danso

Note:

• As part of his pre-doctoral work, Elvis Danso collected mechanical testing data for 30 tissue samples. The findings will be summarized here.
• Tissues tested:
  • Medial/ lateral, femoral and tibial cartilage (indentation and tensile test)
  • Patellar groove, cartilage (indentation and tensile test)
  • Patella (indentation and tensile test)
  • Medial/ lateral menisci (indentation and tensile test)
  • ACL, PCL, MCL, LCL, patellar ligament, quadriceps tendon(tensile test)
• ACL
  • attachment:acl.pdf

Pilot tissue mechanical tests

attachment:sample-list.xls

Sample 1

Sample: Cylindrical compression sample

Tissue: Cartilage

Location: Lateral tibial plateau

Dimensions (measured using LVDT): Thickness = 2.47 mm, Diameter= 5 mm.

Test: Unconfined compression

Data:

attachment:data.txt

Note: Pre-stress value is determined from 1. finding load when the load cell starts accumulating load (as close to zero as possible and as allowed by the load cell resolution) 2.and the area of cross section. For this sample the diameter was measured using a ruler (thickness measurement system is currently not calibrated for >3 mm, need gauges). This prestress value will be used for all the test samples for cartilage compression tests.

Sample 2

Sample: Dumbbell tensile sample

Tissue: Cartilage

Location: Lateral Femoral Condyle

Dimensions (measured using LVDT): Thickness = mm, Length= mm, width = mm

Test: Uniaxial tensile test

Data:

Sample 3

Sample: Dumbbell tensile sample

Tissue: MCL

Location: Mid-substance

Dimensions (measured using LVDT): Thickness = mm, Length= mm, width = mm

Test: Uniaxial tensile test

Data: