Imaging technologist training the osteoarthritic knee 2014
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Transcript of Imaging technologist training the osteoarthritic knee 2014
Carolyn Bonaceto, BSRT(R)(MR)Sr. Manager, Imaging and CAD ManufacturingCONFORMIS, Inc. 28 Crosby Drive | Bedford, MA | 01730Imaging Support - 781.345.9170(O) 781.345.9111 | (F) 781.345.0147 Connect @:www.Conformis.comTwitter: @ConforMISFacebook: ConforMIS PageYouTube: PatientSpecific channel
THE OSTEOARTHRITIC KNEE
COMPANY CONFIDENTIAL © COPYRIGHT 2014 ConforMIS, Inc. 1
• This self-learning activity was approved for .50 Category A ARRT CE credits by the SMRT
• Directed readings, home study courses, or internet activities reported in a biennium may not be repeated for credit in the same or any subsequent biennium
COMPANY CONFIDENTIAL © COPYRIGHT 2014 ConforMIS, Inc. 2
KNEE ANATOMY Osseous Structures and Articulations Internal and External Joint Support
KNEE PATHOLOGY Osteoarthritis Cartilage Injuries
IMAGING CR CT CT Arthroscopy MRI
SURGICAL TREATMENTS Arthroscopy Hemi-Arthroplasty Total Knee Repair
POST SURGICAL FIT ASSESMENT
Outline
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Osseous StructuresFemur-
Longest, largest, strongest skeletal bone Cylindrical shaft made up of cortical
bone and fat filled medullary Condyles defined by trochlea anteriorly
and intercondylar notch posteriorly
• Image from:http://en.wikipedia.org/wiki/Femur
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Knee Anatomy
Osseous StructuresPatella-
Flat triangular sesamoid bone marking the anterior most portion of the knee joint
Thick superior border (base) and pointed inferior border (apex)
Cancellous bone enveloped by the quadriceps tendon
Image from: http://www.fpnotebook.com/_media/orthoLegPatellaAntGrayBB255.gif
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Knee Anatomy
Osseous Structures Tibia-
Large superior portion, head, divided into two distinct portions, the medial and lateral condyles, separated by the tibial spine
Flat superior surface is called the plateau Articulates with the femoral condyles Tibial tuberosity found on the anterior
portion serves as an articulation point for the patellar ligament
Fibula- Most slender of the long bones Articulates anteriorly and laterally with the
lateral tibial condyle
Images from:http://en.wikipedia.org/wiki/Tibiahttp://en.wikipedia.org/wiki/Knee
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Knee Anatomy
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Medial femoral condyle
Femoral shaft, distal end
Lateral femoral condyle
Patella
Medial tibial plateau
Head of fibula
Lateral tibial plateau
Knee Anatomy
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Femoral shaft, distal end
Patella
Tibial plateau
Head of fibulaTibial Tuberosity
Femoral condyles
Knee Anatomy
Cartilage Dense connective tissue
Made up of chondrocytes which produce the extracellular matrix of water, collagen, and proteoglycan Collagen is mostly type II, provides strength and structure No blood supply, nourishment is supplied by synovial fluid
Thickness Normally between 2 and 5mm’s
Thickness can be correlated with highest peak pressure areas. The thickest cartilage in the body is found in the patellofemoral joint
Four distinct zones Superficial zone- highest collagen content which is aligned parallel to the articular
surface, lowest concentration of proteoglycan, 10% to 20% of the overall thickness
Transitional zone- 40% to 60% of the overall thickness, collagen organization is random, composed almost exclusively of proteoglycans
Radial zone- distributes load and resists compression with parallel oriented highly organized collagen fibers, and lowest water content
Calcified cartilage zone- contains the tidemark which signals the transition between calcified and uncalcified cartilage
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Knee Anatomy
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Articular Cartilage
Knee Anatomy
Joint Support External Support
Fibrous Capsule Encloses the joint, consists of
synovial membrane, thin connective tissue which secretes synovial fluid. This thick, high viscosity fluid helps lubricate the knee and reduce friction.
Extracapsular Ligaments Anterior - Patella ligament Lateral – Lateral collateral
ligament Medial – Medial collateral
ligament Posterior- Oblique popliteal
ligament and arcuate ligament
Image from:http://papruddenmor.blogspot.com/2011_05_01_archive.html
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Knee Anatomy
Joint Support Internal Support
Anterior cruciate ligament (ACL) – provides rotation for the joint and prevents displacement anteriorly
Posterior cruciate ligament (PCL)- prevents posterior draw
Image from:http://www.ehealthmd.com/yms_images/anterior_cruciate_375.jpg
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Knee Anatomy
Menisci (from Greek meniskos, “crescent”) Medial and Lateral Fibrocartilaginous concave semicircles Articulates with the tibial plateaus Provides gliding surface for knee movement and absorbs tension
COMPANY CONFIDENTIAL 13
Knee Anatomy
Image from:http://morphopedics.wikidot.com/meniscal-tear
© COPYRIGHT 2014 ConforMIS, Inc.
Muscular SupportExtensors
Quadriceps femoris muscle group Rectus femorisVastus lateralis,Vastus medialusVastus intermedius
FlexorsHamstring muscle group
SemitendinosusSemimembranosusBiceps femoris
Assisting musclesGracilisSartoriusPopliteus COMPANY CONFIDENTIAL © COPYRIGHT 2014 ConforMIS, Inc. 14
Quadriceps tendon
Cortical bone
Cancellous bone
Vastus medialus
Semimembranosus Biceps femoris
Sartorius
Vastus lateralis
Knee Anatomy
Anterior cruciate ligament
Medial femoral condyle
Anterior cruciate ligament
Lateral femoral condyle
Tibial plateau
Head of the fibula
Medial compartment
Lateral collateral ligament
Lateral compartment
Knee Anatomy
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Knee Anatomy
Posterior cruciate ligament
Patellofemoral compartment
Articular cartilage
Tibial spine
Patellar tendon
Quadriceps tendon
Lateral meniscus
Cartilage bone interface
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Knee anatomy and pathology is generally demonstrated using
Routine radiographs, CR/DRCT with or without arthrogram contrastMR with or without arthrogram contrast
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Diagnostic Imaging
CR AP Lateral Tangential (sunrise) Full Leg – used for alignment
measurement
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Demonstrates Cartilage loss/Joint space
narrowing Osteophytes/bone spurs Subchondral cysts Sclerosis Bone marrow edema Traumatic injuries
Diagnostic Imaging
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AP - Position central ray at right angles to the joint space with no rotation. The resulting image should demonstrate the epicondyles in profile and the intercondylar eminence of the tibia centered within the intercondylar fossa of the femur
UnacceptableAcceptable
Diagnostic Imaging
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Lateral -Position central ray at right angles to the joint space with no rotation of the knee. The resulting image should demonstrate the posterior aspects of the femoral condyles superimposed.
Acceptable Unacceptable
Diagnostic Imaging
CT Demonstrates
Joint space narrowing Subchondral cysts Sclerosis Osteophyte formations
Reconstructions Axial Sagittal Coronal images
CT Arthrogram The use of diluted contrast in joint
delineates articular cartilage and ligaments
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MRI Used to evaluate soft tissue
structures Grade articular cartilage
damage Evaluate ligaments integrity Evaluate meniscal tears
*Knee MR protocols vary from site to site and can be dependent on the system
used to acquire the images*
Diagnostic Imaging
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Pathology commonly associated with patients considering a knee implant Osteoarthritis (OA) – defined as chronic inflammation characterized by
degeneration of the joints causing pain, stiffness, and swelling. OA is sometimes referred to as degenerative joint disease (DJD). Radiographically OA can be identified by the presence of osteophytes, bone edema, sclerosis, joint space narrowing and cyst formations.
Osteochondritis Defects (or Dissecans) (OCD) is characterized by cracks that occur in the articular cartilage and the underlying subchondral bone as a result of decreased blood flow. Avascular necrosis (AVN) or bone death as a result of the loss of blood flow leaves the articular cartilage vulnerable. Fragmentation of cartilage and bone, and subsequently loose bodies occur within the joint space, causing pain and additional damage. Radiographically loose bodies (bone fragments) can be seen. MR images demonstrate and stage OCD lesions in the cartilage.
Knee Pathology
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Osteoarthritis (OA)Morbidity
Affects as many as 26.9 million AmericansOne of the most common causes of disability due to limitations in joint movement. By age 40 almost 90% of the American population will have some form of OA in their weight-bearing joints OA results in 632,000 joint replacements each year300,000 TKR surgeries annually in the US for end-stage arthritis of the knee joint.
Causes ObesityGeneticsTraumaMetabolic disorders
SymptomsPain SwellingLoss of mobility
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OsteoarthritisJoint space narrowing
AP Lateral
Osteophyte formation
Tangential View (aka sunrise or merchant view)
Osteophyte
Weight bearing AP knees
Note- Because the image was acquired bilaterally neither knee is demonstrated in a true AP position since the central beam was focused between the knees.
OsteoarthritisJoint space narrowing
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Osteoarthritis
Image from:http://www.washingtonknee.com/knee-treatments/knee-osteoarthritis/
Osteophyte
Grade 1- Superficial lesions, cracks, and indentations
Grade 2 - Fraying, lesions extending down to <50% of cartilage depth
Grade 3 - Partial loss of cartilage thickness, cartilage defects extending down to >50% of cartilage depth as well as down to calcified layer
Grade 4 - Complete loss of cartilage thickness, bone only
ICRS Hyaline Cartilage Lesion Classification System
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Grade 4 articular cartilage loss- exposed subchondral bone, complete loss of cartilage
Grade 3 articular cartilage loss - >50%
Grade 3 articular cartilage loss - > 50%
Grade 4 articular cartilage loss- exposed subchondral bone, complete loss of cartilage
Cartilage LossMR images
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Grade 3 articular cartilage loss - >50%
Grade 3 articular cartilage loss - > 50%
Grade 4 articular cartilage loss- exposed subchondral bone, complete loss of cartilage
Grade 4 articular cartilage loss- exposed subchondral bone, complete loss of cartilage
Cartilage LossCT Arthrogram images
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Grade 3 articular cartilage loss - > 50%
Subchondral CystMR images
Osteophyte formation
Osteophyte formation
Subchondral cyst
Subchondral cyst
Subchondral cyst
Subchondral cyst
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Grade 3 articular cartilage loss - > 50%
Subchondral CystCT Arthrogram images
Osteophyte formation
Osteophyte formation
Subchondral cystSubchondral cyst
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SclerosisCR Images
Sclerotic changes – increased bone density
Sclerotic changes – increased bone density
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Bone Marrow EdemaMRI Image
Bone marrow edema
Osteochondritis Defect (OCD)
Injury to the cartilage and underlying bone
Results from interrupted blood flow to the area
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Osteochondritis Defect (OCD)
Stage Appearance on MRI & Stability of lesion Stage 1- Articular Cartilage Damage only Stage 2 - Cartilage injury with underlying fracture
a. Surrounding bony edema b. Without edema
Stage 3 - Detached but non-displaced fragment Stage 4 - Detached and displaced fragment
COMPANY CONFIDENTIAL © COPYRIGHT 2014 ConforMIS, Inc. 35
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OCD-MRI Image
Stage II OCDStage II OCD
COMPANY CONFIDENTIAL © COPYRIGHT 2014 ConforMIS, Inc. 37
OCD-MRI Image
Stage II OCD
Stage II OCD
Stage III OCDStage IV OCD
Surgical Treatments
Surgeons- Seek the least invasive method Encourage bone preservation
Less bleeding and post surgical pain Shorter recovery times Still have bone to work with for potential revisions; Prosthesis failure
rate requiring revision is ~1 percent per year
COMPANY CONFIDENTIAL © COPYRIGHT 2014 ConforMIS, Inc. 38
Surgical Treatments
Arthroscopy – via a scope inserted through a small incision the surgeon views the joint capsule and can perform small repairs including removal of damaged cartilage and any loose bodies.
Hemi-Arthroplasty –
Uni-compartmental Arthroplasty – this procedure replaces only the damaged area of a single joint compartment with a prosthetic device.
Duo-compartmental Arthroplasty – this procedure replaces only the damaged area of the patella femoral joint and either the medial or the lateral compartment with a prosthetic device.
Osteotomy – a high tibial osteotomy involves removal of a wedge shaped piece of bone that results in realignment allowing the patients weight to be distributed away from the damage compartment.
Total Knee Arthroplasty – involves replacing all joint surfaces
COMPANY CONFIDENTIAL © COPYRIGHT 2014 ConforMIS, Inc. 39
“The success of primary TKR in most patients is stronglysupported by more than 20 years of followup data. Thereappears to be rapid and substantial improvement in thepatient's pain, functional status, and overall health-relatedquality of life in about 90 percent of patients; about 85 percentof patients are satisfied with the results of surgery.”
-NIH Consensus Statement on Total Knee Replacement
COMPANY CONFIDENTIAL © COPYRIGHT 2014 ConforMIS, Inc. 40
Surgical Treatments
Surgical Treatments
COMPANY CONFIDENTIAL © COPYRIGHT 2014 ConforMIS, Inc. 41
ConforMIS iUni® is a Uni-Compartmental Device
ConforMIS iTotal® is a Total Knee Device
ConforMIS iDuo® is a Bi-Compartmental Device
ConforMIS CT Order Form
COMPANY CONFIDENTIAL © COPYRIGHT 2014 ConforMIS, Inc. 42
ConforMIS CT Protocol Immobilize the patient and remind them of the importance of holding still for the exam.
The patients toes should be straight up.
Do not place a pillow or bolster under the affected knee so that alignment between the hip, knee and ankle is maintained.
If the patient has an implant in the opposite knee please bend that knee out of the way so that the artifact does not run through the joint space of the knee of interest.
Slice positioning is critical. Please review the guides for examples of proper positioning.
Always check all series to verify that your scan meets coverage requirements and that there are no motion artifacts.
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ConforMIS CT Protocol
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Series
1 Scout FULL LEG, Hip through Ankle
Kernel /Algorithm
AxialReconstruction
Thickness X Increment
Projection
2Hip – Femoral head
only(acetabulum only)
Bone2mm X 2mm
or2.5mm X 2.5mm
Axial
3
Knee – distal 1/3 of the femur through
proximal 1/3 of tibia (should include the
entire patella through the fibula
head)
Bone1mm X .5mm
or1.25mm
X .625mm Axial
4
Ankle – center at tibiotalar joint space scan 2cm above the joint to 2cm below
Bone2mm X 2mm
or2.5mm X 2.5mm
Axial
5Multi Planar
Reformat– knee only
Bone 1mm X 1mm Coronal
6Multi Planar
Reformat– knee only
Bone 1mm X 1mm Sagittal
Post Surgical Radiographic Assessment
COMPANY CONFIDENTIAL © COPYRIGHT 2014 ConforMIS, Inc. 45
Routine CR images are acquired as part of a clinical assessment of patients post knee arthroplasty to evaluate for common post operative complications that can cause pain and the need for revision surgeries.
Assess for fit – overhang or underhang of either component can lead to post–op pain
Alignment – one of the goals of PKR or TKR is to restore mechanical alignment
Loosening – Failure of PKR and TKR can be associated with component loosening
Osteolysis – bone reabsorption can occur in the area of the prosthetic
Wear – can occur in some of the components of the prosthetic
Post Surgical Radiographic Assessment
COMPANY CONFIDENTIAL © COPYRIGHT 2014 ConforMIS, Inc. 46
Proper positioning is critical- unless directed to do so by your radiologists or the orthopedic surgeon avoid bilateral images. The central beam should be directed at the knee joint
Weight bearing full leg –assess for alignment and leg length
AP and Lateral – assess for component position and fit
Tangential (aka sunrise or merchant view) – demonstrates the PF joint
Post Surgical Radiographic Assessment
AP
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Acceptable positioning Poor positioning
Post Surgical Radiographic Assessment
Lateral
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Acceptable positioning Poor positioning
Post Surgical Radiographic Assessment
Tangential
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Acceptable positioning Poor positioning
Post Test1. The Patella is cancellous bone surrounded by the _____________
a. Lateral collateral ligamentb. Medial collateral ligamentc. Patella tendond. Quadriceps tendon
2. Normal knee cartilage is between ________ thicka. 2 and 5mm’s b. 1 and 3mm’sc. 6 and 7mm’sd. None of the above
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Post Test3. Cartilage is dense connective tissue that is ___________
a. Made up of chondrocytes which produce the extracellular matrix of water, collagen, and proteoglycan
b. Collagen which is mostly type II, providing strength and structurec. Has no blood supply, nourishment is supplied by synovial fluidd. All of the above
4. The following statement is true regarding diagnostic imaging of the knee.a. Joint space narrowing can only be identified on CT imagesb. CT arthrography will not help in the evaluation of articular cartilage lossc. CR images can demonstrate osteophyte formations d. MR images will not demonstrate soft tissue structures
COMPANY CONFIDENTIAL © COPYRIGHT 2014 ConforMIS, Inc. 51
Post Test5. A true AP CR image of the knee is acquired with
a. Bilaterally with the central beam between the kneesb. Uni laterally with the central beam focused at the joint spacec. Bilaterally with the central beam focused on one knee or the otherd. The knee bent 30 degrees
6. Osteoarthritis can be identified radiographically by the presence ofa. Osteophytes and bone edemab. Sclerosis and cyst formationsc. Joint space narrowingd. All of the above
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Post Test7. By age 40 almost______of the American population will have some form of OA in their weight-
bearing joints a. 100%b. 50%c. 90% d. 20%
8. Osteoarthritis is caused by __________________e. Genetics and metabolic disordersf. Traumag. Obesityh. All of the above
COMPANY CONFIDENTIAL © COPYRIGHT 2014 ConforMIS, Inc. 53
Post Test9. The Hyaline Cartilage Lesion Classification System (2000) describes Grade 4 lesions as
a. Superficial lesions, cracks, and indentationsb. Fraying, lesions extending down to <50% of cartilage depth 0 and 2mm’sc. Partial loss of cartilage thickness, cartilage defects extending down to >50% of cartilage
depth as well as down to calcified layerd. Complete loss of cartilage thickness, bone only
10. The Hyaline Cartilage Lesion Classification System (2000) describes Grade 2 lesions asa. Superficial lesions, cracks, and indentationsb. Fraying, lesions extending down to <50% of cartilage depth 0 and 2mm’s c. Partial loss of cartilage thickness, cartilage defects extending down to >50% of cartilage
depth as well as down to calcified layerd. Complete loss of cartilage thickness, bone only
COMPANY CONFIDENTIAL © COPYRIGHT 2014 ConforMIS, Inc. 54
Post Test11. Sclerotic changes are identified as
a. Decreased bone densityb. Increased bone density c. Bone edemad. Bone cysts
12. Osteochondritis defects result from ___________a. injury to the cartilage and underlying boneb. Interrupted blood flow to the areac. (a) and (b) d. None of the above
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13. Osteochondritis Defects Stage III is identified on MRI by _____________a. Articular Cartilage Damage onlyb. Cartilage injury with underlying fracture c. Detached but non-displaced fragment d. Detached and displaced fragment
14. Osteochondritis Defects Stage IV is identified on MRI by _____________a. Articular Cartilage Damage onlyb. Cartilage injury with underlying fracture c. Detached but non-displaced fragment d. Detached and displaced fragment
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Post Test
15. Bone preservation is desirable because ______. a. Surgeons prefer to seek the least invasive methodb. Surgical procedures that involve fewer bone cuts result in less bleeding and post surgical
pain, and shorter recovery time.c. Less drastic approaches to surgical repair early on means that later there is still bone to
work with when total knee arthroplasty is the only solutiond. All of the above
16. Prosthesis failure rate requiring revision is approximately _____ percent per yeare. 1 f. 5g. 15h. 25
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Post Test
17. ________ hemi arthroplasty replaces only the damaged area of a single joint compartment with a prosthetic device
a. Duo compartmentalb. Uni compartmental c. (a) and (b) d. None of the above
18. High tibial osteotomy is a procedure that ___________a. involves removal of a wedge shaped piece of bone b. results in realignment c. allows the patient’s weight to be distributed away from the damage compartment d. All of the above
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Post Test
19. Post surgical CR images are acquired to ___________a. Evaluate implant fitb. Assess for osteolysisc. Evaluate leg alignment d. All of the above
20. The Tangential view (aka sunrise or merchant view) is acquired to demonstrate the ___________
a. Lateral compartment of the knee jointb. Medial compartment of the knee jointc. Patellafemoral jointd. Tibiotalar joint
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Post Test