This page provides specifications of knee specimen OKS004. This is a pilot specimen to go over the whole experimentation process.

TableOfContents()

Specimen Characteristics

Right knee

Gender: Female

Age: 46 years

Race: White

Height: 62 in. (1.575 m)

Weight: 120 lbs. (54.43 kg)

BMI: 21.9

Serologically tested: Yes

X-Ray

attachment:right-xray.png

Experimentation

Specimen

Reference Specification: ["Specifications/Specimens"] - [http://wiki.simtk.org/openknee/Specifications/Specimens?action=recall&rev=40 Revision as of April 28, 2014]

Leading Team Member: Snehal Chokhandre

Supporting Team Members:

Timeline:

Data Location:

Protocol Deviations:

1. Specimen Characteristics. Donor age (46 yrs) does not match specifications.

2. Specimen Size. The specimen is not hip to toe rather mid-femoral shaft to toe.

Notes:

• None

Specimen Preparation

Reference Specification: ["Specifications/SpecimenPreparation"] - [http://wiki.simtk.org/openknee/Specifications/SpecimenPreparation?action=recall&rev=114 Revision as of July 9, 2014]

Leading Team Member: Tara Bonner

Supporting Team Members: Snehal Chokhandre, Craig Bennetts, Dylan Beckler, Katie Stemmer

Timeline:

• Specimen Thawing: 22.5 hours (12:30pm 7-20-14 to 11:00am 7-21-14)
• Specimen Dissection: 1.75 hours (12:45pm-2:30pm 7-21-14)
• Optotrak Base Plug Placement on Bones: 1.5 hours (2:35pm-4:10pm 7-21-14)
• Potting: 35 minutes (1:25pm-2pm 7-22-14)

Data Location:

• Patella Registration and Optotrak Marker Alignment:
  • Sensor in state files are saved in main configuration folder for project
  • The two data files are found in specimen configuration folder
    1. digitized_MRI_marker_state.cfg
    2. Patella_sensor_to_Reference.tdms

Protocol Deviations:

1. Femur Anatomical Landmarks. As the specimen did not include femoral head, landmarks on femoral shaft at its most proximal circumference were digitized.

Notes:

1. Registration Markers - Preparation. Drilling axis (for screw placement) and marker center are not concentric. Careful handling is necessary not to rotate the markers after their installation on bones. Preparation of the markers beforehand, by drilling on the lathe may be helpful to establish concentricity.

2. Registration Markers - Digitization. Digitization order for femur spherical markers are: 1 - anteromedial, 2 - medial, 3 - lateral. Digitization order for tibia spherical markers are: 1 - lateral, 2 - medial, 3 - posterior.

3. Specimen Dissection

   • Mention that quad tendon must be isolating by removing fat around it and then kept moist with saline towel (suggest using tweezers and squeezing to remove muscle that is on tendon)
   • Mention that four inch strip of tibia and fibula shafts must be completely cleaned 360 degrees around shaft and should be made as far proximal as possible without damaging joint capsule to allow room for plugs
   • Add that fibula should be fixed to tibia for MRI

4. Optotrak Base Plug Placement on Bones

   • From step 2: Specify that 3 plastic optotrak plugs are needed
   • From step 5:
     • Oks004 had the 2 screw holes on posterior side instead of anterior side
     • Mention if a screw shears off it is okay to have 2 full screws and a sheared one in the plug
     • Mention if all screws shear then remove screws and try drilling bigger holes first (tip: test with non-cemented screws first to see if they shear)
     • Suggest using k-wire in one hole to hold plug still when screwing in others
     • Suggest checking that drill bit is short enough to prevent going through cartilage on patella (from section 3 of step 5)
     • Mention cut vertical line in skin over patella and pull apart sides to make room for plug (from section 3 of step 5)
   • From step 6: mention wiping off excess cement from screw before inserting
   • General:
     • have section on cement
       • suggest making small batches and doing one plug at a time to avoid cement hardening before you are ready
       • mention that if cement clumps up when screwing in then it is time for new batch
       • Add caution that cement should be made in a hood and masks should be worn

5. Registration Marker Placement on Femur and Tibia

   • From step 1: mention that it is being driven by field of view from MRI spec
   • General: Specify drill bit size, specify type of retractor (mention to check that it is sharp for grip), mention that tissue must be cut to make room for spheres

6. Preparation of Specimen for Mechanical Joint Testing

   • Oks004 fibula was screwed/fixed to tibia at this point
   • suggest checking that sensors will fit on plugs with the pot before actually potting
   • mention removing wood metal that hardens over edge of pot with chisel
   • mention liquid nitrogen is used to secure tendon
   • mention that chuck should be used to protect knee when pouring liquid nitrogen onto tendon
   • 0ks004 liquid nitrogen was added to tendon every 15-20 minutes
   • consider smaller grommet size
   • explain that size of sensor is determined by if it is small enough to fit in knee and large enough to collect all data
   • From step 4 mention to check during dissection if any important features were cut when incisions were made

Joint Imaging

Specimen Preparation

Reference Specification: ["Specifications/SpecimenPreparation"] - [http://wiki.simtk.org/openknee/Specifications/SpecimenPreparation?action=recall&rev=114 Revision as of July 9, 2014]

Leading Team Member: Craig Bennetts

Supporting Team Members: Snehal Chokhandre

Timeline:

Data Location:

Protocol Deviations:

1. Patella registration marker assembly was not placed on the patella for imaging. This can be prevented by cross-checking with specifications. Alternative imaging or digitization is necessary to align patella local coordinate systems between imaging and motion analysis. This can be accomplished by i) imaging patella only with the registration marker assembly after dissection, or ii) by digitizing patella anatomy using Optotrak along with patella motion analysis markers. Snehal will follow up to resolve this issue.
2. As an alternative solution to obtain the transformation matrix between the patella Optotrak marker coordinate system to image coordinate system, 48 points on the anterior bony surface of the patella was digitized using the Optotrak probe. First (and last) three points correspond to lateral, medial, and inferior points, respectively.

Notes:

Imaging

Reference Specification: ["Specifications/ExperimentationAnatomicalImaging"] - [http://wiki.simtk.org/openknee/Specifications/ExperimentationAnatomicalImaging?action=recall&rev=117 Revision as of June 25, 2014]

Leading Team Member: Craig Bennetts

Supporting Team Members: Snehal Chokhandre, Katie Stemmer

Timeline:

Data Location:

1. SEQUENCE 2: General Purpose Imaging
   • t1_f13d_sag_p2_150_0.4_we
     • Position R1.5 A20.3 F4.4
2. SEQUENCE 3: Cartilage Imaging
   • t1_f13d_sag_350x350x700_fs
     • Position R1.5 A20.3 F4.4
3. SEQUENCE 4: Connective Tissue Imaging
   • pd_tse_sag_1.4mmslice_1avg_axial
     • Position L0.7 A21.8 F1.5
   • pd_tse_sag_1.4mmslice_1avg_sag
     • Position L2.9 A18.2 H8
   • pd_tse_sag_1.4mmslice_1avg_coronal
     • Position L.2.9 A18.2 H8

Protocol Deviations:

1. After localizer we ran ACRT1 Axial test (a localizer/scout)

Notes:

1. General purpose imaging seems very noisy; data source SEQ1_t1_fl3d_sag_iso_0.4_we (@ staging server for data organization)

   • ImageLink(oks004-SEQ1_t1_fl3d_sag_iso_0.4_we.png, width=400)

2. Cartilage imaging seems acceptable; data source SEQ2_t1_fl3d_sag_350x350x700_fs_11 (@ staging server for data organization)

   • ImageLink(oks004-SEQ2_t1_fl3d_sag_350x350x700_fs_11.png, width=400)

3. Connective tissue imaging (axial) seems acceptable; data source SEQ3_pd_tse_sag_1.4mmslice_1avg_axial (@ staging server for data organization)

   • ImageLink(oks004-SEQ3_pd_tse_sag_1.4mmslice_1avg_axial.png, width=400)

4. Connective tissue imaging (sagittal) seems acceptable; data source SEQ4_pd_tse_sag_1.4mmslice_1avg_sagittal_10 (@ staging server for data organization)

   • ImageLink(oks004-SEQ4_pd_tse_sag_1.4mmslice_1avg_sagittal_10.png, width=400)

5. Connective tissue imaging (coronal) seems to be a repetition of sagittal scan; data source SEQ5_pd_tse_sag_1.4mmslice_1avg_coronal (@ staging server for data organization)

   • ImageLink(oks004-SEQ5_pd_tse_sag_1.4mmslice_1avg_coronal.png, width=400)

Joint Mechanics

Equipment Preparation

Reference Specification: ["Specifications/PressureCalibration"] - [http://wiki.simtk.org/openknee/Specifications/PressureCalibration?action=recall&rev=11 Revision as of July 17, 2014]

Leading Team Member: Jason Halloran

Supporting Team Members: Robb Colbrunn, Katie Stemmer

Data Location:

Timeline:

Protocol Deviations:

Notes:

1. Mention that equilibration might have to be run twice in order to successfully equilibrate sensor

Specimen Preparation

Reference Specification: ["Specifications/SpecimenPreparation"] - [http://wiki.simtk.org/openknee/Specifications/SpecimenPreparation?action=recall&rev=114 Revision as of July 9, 2014]

Leading Team Member: Tara Bonner

Supporting Team Members: Snehal Chokhandre, Craig Bennetts, Dylan Beckler, Ahmet Erdemir

Timeline:

Data Location:

Protocol Deviations:

Notes:

1. The specifications did not explicitly detail securing of the fibula to the tibia. A drill bit was passed through the fibula and the tibia to prevent fibula's movements during tibiofemoral joint testing. It may be necessary to secure fibula to the tibia during specimen preparation (before detaching the foot) to approximate anatomical alignment. This will require MRI compatible screws, etc. and will ensure keeping the fibula at the same position relative to the tibia in imaging and during robotics testing.

Testing

Reference Specification: ["Specifications/ExperimentationJointMechanics"] - [http://wiki.simtk.org/openknee/Specifications/ExperimentationJointMechanics?action=recall&rev=81 Revision as of May 25, 2014]

Leading Team Member: Tara Bonner

Supporting Team Members: Snehal Chokhandre, Craig Bennetts, Katie Stemmer, Jason Halloran, Ahmet Erdemir

Data Location:

Timeline:

Protocol Deviations:

1. For tibiofemoral joint testing, the knee was assembled upside down. This approach circumvented the need for gravity compensation during force measurements. The tibia was fixed directly to the load transducer, which was assembled on the testing frame.
2. For patellofemoral joint testing, 20N compressive force for tibiofemoral joint was applied to increase stability

Notes:

1. For tibiofemoral joint testing, reprogramming of the robotics testing system was required to accommodate optimization of the joint coordinate system.
2. During tibiofemoral joint testing, the control system had issues loading the knee joint flexed at 90 degrees with a 2.5 Nm valgus moment from an unloaded state. This may be related to a possible singularity of the robot configuration.
3. During tibiofemoral joint testing at 90 degrees flexion, visibility of the femur Optotrak markers was problematic.
4. During patellofemoral joint testing, the knee needed to be oriented axially to accommodate loading direction of the quadriceps tendon. This caused the loss of tibia Optotrak marker data. Robotic system provides redundant information to reconstruct relative locations of patella, femur, and tibia.
5. For patellofemoral joint testing, measurement of quadriceps line of action needs to be detailed.
6. During patellofemoral joint testing, patellofemoral kinematics data were not recorded for 0, 15, and 30 degrees flexion conditions. These conditions were repeated. In both case cases (initial and repeat) pressure data were collected.
7. Knee should be aligned obliquely to accommodate line of action of quad because tibia markers are lost and data is not seen in camera
8. During laxity testing at higher flexion angles (30, 60 and 90) non-zero external rotation torque caused the "Anterior Drawer" laxity condition to not truly be an anterior drawer test. The AP translations were not proportional to the AP loads due to coupling with ER rotation. In the future, attention should be made to ensure off-axis loads are zero during laxity testing. Gains and/or settling time can be increased to ensure this.

Tissue Mechanics

Specimen Preparation

Reference Specification: ["Specifications/SpecimenPreparation"] - [http://wiki.simtk.org/openknee/Specifications/SpecimenPreparation?action=recall&rev=114 Revision as of July 9, 2014]

Leading Team Member: Snehal Chokhandre

Supporting Team Members: Craig Bennetts

Timeline:

Data Location:

Protocol Deviations:

Notes:

Testing

Reference Specification:

Leading Team Member: Snehal Chokhandre

Supporting Team Members:

Data Location:

Timeline:

Protocol Deviations:

Notes:

1. The knee joint was dissected by a fellow. Observations during dissection noted no apparent injuries or damage to knee structures and cartilage.
2. Same compression sample is used for both unconfined and confined compression. Sample lable ends with -01. Data label ends with 01 for unconfined and 02 for confined compression.

oks004-FMC-ACXX-01

• Thickness: 2.457 mm

  DAQ : 100Hz

  No video

  Room tempterature

result:

Data Analysis

Modeling & Simulation