Note:

• The following document is a working draft of in vitro protocol and likely to change until stated otherwise

Decisions to make

...

PART I: Indentation

See Specifications/InVitroTesting/PartII for Part II: Surgery

Logistics

Target Outcome

• Demographic documentation (age, gender)
• Anthropometric measurements (body mass, height, extremity lengths and circumferences)
• A set of MR and CT images of upper and lower leg.
• Ultrasound images at unloaded state to extract tissue thickness for various extremity locations
• Ultrasound imaging during indentation to extract tissue thickness for various extremity locations
• Mechanical testing of tissue and tissue-interface to characterize mechanical properties at ultrasound indentation locations

Prerequisites

Specifications

• Specifications/Specimen

• Specifications/SpecimenPreparation

• Specifications/Labeling

• Specifications/MagneticResonanceImaging

• Specifications/CT

Infrastructure

• Infrastructure/TestingRoom

• ImagingFixture

• Infrastructure/InstrumentedUltrasound

• Infrastructure/InstrumentedSurgicalTools

• Infrastructure/MagneticResonanceImaging

• Infrastructure/TissueCharacterization

• Infrastructure/SpatialStrainMeasurement

• Infrastructure/MotionAnalysis

• Infrastructure/DigitalVideo

• Infrastructure/HapticInterfaces

• Infrastructure/SimulationSoftware

• Infrastructure/DataManagement

Protocols

Input

Cadaver upper and lower legs and arms of the same donor. See Specifications/Specimen for details.

Procedures

Supplies/Equipment needed for experimentation

• Supplies: scalpel, forceps, 16 registration markers, Optotrak sensor (for specimen), Optotrak sensor (for ultrasound), drill, drill bit+tap 8-32 (for registration markers), drill bit (pre-drill for screws), drill bit+tap (for Optotrak sensor plug), ultrasound gel, pens, washable markers, cloth tape measure, wash cloths
• Equipment: Optotrak camera system, Optotrak probe, Ultrasound system with foot-switch, 14L5 probe, 9L4 probe, probe casings, load-transducer computer, load-transducer unit, ATI IFPS box, blue DAQ unit, beige DAQ unit, cadaver fixture

Antropometric Measurements

Refer to in vivo protocol as it is the same.

Specimen Preparation for MRI/Indentation

One specimen (e.g. Upper and Lower Leg) will be used at a time. See Specifications/SpecimenPreparation for details.

MRI protocol

See

• Specifications/MagneticResonanceImaging

• Infrastructure/MagneticResonanceImaging

Preparing Ultrasound

Refer to in vivo ultrasound set-up as it is the same.

Optotrak Marker Assembly on Bones

• Mounting of Optotrak markers:

• Leg

  1. Place the femur Optotrak marker on femur base plug
  2. Place the tibia Optotrak marker on tibia base plug

• Arm

  1. Place the radius Optotrak marker on radius base plug
  2. Place the humerus Optotrak marker on humerus base plug

Acquisition of Registration Marker Locations

1. Registration marker data collection
   1. Keep specimen within Optotrak measurement view.
   2. Use the digitizing probe to record registration marker locations along with Optotrak marker position/orientation output, measured with respect to the global Optotrak coordinate system for each respective bone
   3. Ten points on each spherical marker should be digitized such that they are distributed evenly about the sphere surface
   4. The spheres should be digitized in the following order:

2. Leg

   1. Femur
      1. F1. Anterior neck
      2. F2. Superior neck
      3. F3. Posterior neck
      4. F4. Lateral epicondyle
      5. F5. Posterior lateral condyle
      6. F6. Medial epicondyle
   2. Tibia
      1. T1. Laterial tibial condyle
      2. T2. Tibial tuberosity
      3. T3. Medial tibial condyle
      4. T4. Anterior margin
      5. T5. Distal anterior lateral surface
      6. T6. Medial malleolus

3. Arm

   1. Humerus
      1. H1. H1-H3 equidistant around circumference of head interface
      2. H2. H1-H3 equidistant around circumference of head interface
      3. H3. H1-H3 equidistant around circumference of head interface
      4. H4. Lateral epicondyle
      5. H5. Medial epicondyle
      6. H6. 1 cm superior of olecranon fossa (distal posterior middle)
   2. Radius
      1. R1. 1 cm superior of styloid process (distal lateral)
      2. R2. 1 cm lateral and superior of distal radioulnar joint (distal anterior medial)
      3. R3. Distal posterior middle
      4. R4. Lateral neck (superior lateral just below head)
      5. R5. Posterior neck (superior posterior just below head)

Ultrasound Indentation

Refer to in vivo wiki as it is the same protocol.

Tissue Harvesting

A region of tissue (skin fat muscle) will be excised from the indentation region of the thigh. This will be labeled and immediately frozen as is. Samples will be cut to size prior to mechanical testing.

Mechanical Testing

Need:

• Skin and Muscle Punch (dumbbell)
• Fat Punch (cylinder)

Preparation

Six equally sized samples will be collected from the indentation region. The region will be excised, then samples will be dissected.

• 

• Skin
  • 3 dumbbell strips at 45 degree orientation to each other using punch

  • 

• Fat
  • 1 cylindrical sample
    • how will this be excised?

    

• Muscle
  • 1 cylindrical sample along transverse axis
    • how will this be excised?
  • 1 dumbbell shaped sample

  • 

• Equally sized samples will be collected from the various interfaces
  • Skin-fat
  • Skin-muscle
  • Muscle-muscle
  • Fat-muscle (if any)
• 4 samples from each interface will be collected
  • Cylindrical shape across the interface
  • Strip across interface
  • Strip along interface (tensile test)
  • Strip along interface (shear test)

Testing

Tensile Testing

• Samples to be tested
  • 3 dumbbell skin
  • 1 dumbbell muscle
  • Strip across interface (4 total)
  • Strip along interface (4 total)

Compression (unconfined)

• Samples to be tested
  • Cylinder fat
  • Cylinder muscle ( + fascia) transverse axis
  • Cylinder samples across each interface (4 total)

Failure Tests

• yield, ultimate strength, failure strain each tissue sample

Output

Preliminary Work