The osteoarthritic knee and hip 2016

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COMPANY CONFIDENTIAL © COPYRIGHT 2016-2017 ConforMIS, Inc. 2

Outline
COMPANY CONFIDENTIAL
© COPYRIGHT 2016-2017 ConforMIS, Inc. 3
KNEE
ANATOMY
IMAGING
OA PATHOLOGY
SURGICAL TREATMENTS
POST SURGICAL FIT ASSESMENT
HIP
ANATOMY
IMAGING
OA PATHOLOGY
SURGICAL TREATMENTS

Knee Anatomy
Osseous Structures
 Femur-
 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

Knee Anatomy
Patella-
 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

Knee Anatomy
 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/Tibia
http://en.wikipedia.org/wiki/Knee

Medial femoral condyle
Femoral shaft, distal end
Lateral femoral condyle
Patella
Medial tibial
plateau
Head of fibula
Lateral tibial plateau
Knee Anatomy

Femoral shaft, distal end
Patella
Tibial plateau
Head of fibula
Tibial 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
Knee Anatomy

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
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
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
Knee Anatomy

Muscular Support
Extensors
Quadriceps femoris muscle group
Rectus femoris
Vastus lateralis,
Vastus medialus
Vastus intermedius
Flexors
Hamstring muscle group
Semitendinosus
Semimembranosus
Biceps femoris
Assisting muscles
Gracilis
Sartorius
Popliteus
Vastus medialus
Quadriceps tendon
Cancellous bone
Vastus lateralis
Biceps femorisSemimembranosus
Cortical bone
Sartorius
Knee Anatomy

Knee Anatomy
Lateral collateral
ligament
Anterior cruciate
ligament
Medial
compartment
Lateral
compartment
Lateral femoral
condyle
Medial femoral
condyle
Anterior cruciate
ligament
Head of the
fibula
Tibial plateau

Knee Anatomy
Patellofemoral compartment
Quadriceps
tendon
Patella
r
tendon
Tibial
spine
Posterior cruciate
ligament
Cartilage bone interface
Articular cartilage
Lateral
meniscus

Knee Imaging
Knee anatomy and pathology is generally demonstrated using
Routine radiographs, CR/DR
CT with or without arthrogram contrast
MR with or without arthrogram contrast

Knee Imaging
CR
AP
Lateral
Tangential (sunrise)
Full Leg – used for alignment
measurement
Demonstrates
Cartilage loss/Joint space
narrowing
Osteophytes/bone spurs
Subchondral cysts
Sclerosis
Bone marrow edema
Traumatic injuries

Knee Imaging
UnacceptableAcceptable
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

Knee Imaging
Acceptable Unacceptable
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.

Knee Imaging
CT
Demonstrates:
Joint space narrowing
Sclerosis
Osteophyte formations
CT Arthrogram
The use of diluted contrast in joint
delineates articular cartilage and
ligaments
MRI
Demonstrates
Grade of articular cartilage
damage
Ligaments integrity
Meniscal tears
*Knee MR protocols vary from site to site
and can be dependent on the system
used to acquire the images*

Knee Pathology
 Pathology commonly associated with patients considering a
knee arthroplasty
 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.

Osteoarthritis (OA)
Morbidity
Affects as many as 26.9 million Americans
One 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 year
300,000 TKR surgeries annually in the US for end-stage arthritis of the knee joint.
Causes
Obesity
Genetics
Trauma
Metabolic disorders
Symptoms
Pain
Swelling
Loss of mobility

Osteoarthritis
Joint space narrowing
AP Lateral
Osteophyte formation
Tangential View
(aka sunrise or
merchant view)

Osteoarthritis
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.
Weight bearing AP knees

Osteoarthritis
Image from:
http://www.washingtonknee.com/knee-treatments/knee-osteoarthritis
/

ICRS Hyaline Cartilage Lesion
Classification System
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

Grade 4 articular cartilage loss-
exposed subchondral bone,
complete loss of cartilage
Grade 3 articular cartilage
loss - >50%
Grade 3 articular
cartilage loss - > 50%
exposed subchondral bone,
complete loss of cartilage
Cartilage Loss
MR images

Grade 3 articular cartilage loss -
>50%
loss - > 50%
exposed subchondral bone, complete
loss of cartilage
Grade 4 articular cartilage loss- exposed
subchondral bone, complete loss of
cartilage
Cartilage Loss
CT Arthrogram images

Subchondral Cyst
MR images
loss - > 50%
Subchondral cyst
Subchondral cyst
Subchondral cyst
Subchondral cyst

Subchondral Cyst
CT Images
loss - > 50%
Subchondral cystSubchondral cyst

Sclerosis
CR Images
Sclerotic changes –
increased bone density
Sclerotic changes –
increased bone density

Bone Marrow Edema
MR Image
Bone marrow edema

Results
From interrupted blood flow to the area
Injury to the cartilage and underlying bone
Osteochondritis Defect (OCD)

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

Stage II OCD
Stage II OCD
OCD
MR images

Stage II OCD
Stage II OCD
Stage III OCDStage IV OCD
OCD
MR images

Surgical Treatments - Knee
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

 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

“The success of primary TKR in most patients is strongly
supported by more than 20 years of followup data. There
appears to be rapid and substantial improvement in the
patient's pain, functional status, and overall health-related
quality of life in about 90 percent of patients; about 85 percent
of patients are satisfied with the results of surgery.”
-NIH Consensus Statement on Total Knee Replacement

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

ConforMIS CT Protocol
Patient Identification
DICOM data reflects patient’s legal name with supporting documentation.
Patient Position
The patient’s foot is perpendicular to the table.
Toes up, use positioning aids if available.
Device in the opposite knee? Bend that knee prior to acquiring any images to avoid
scatter (see image). If available use an artifact reduction technique.
No pillows or sponges under the knee or ankle of interest.
Immobilization is essential, remind the patient to hold as still as possible.
Remove foreign objects from field.

Exam Acquisition and Scan Review (also see side two)
Bilateral Imaging is acceptable. Please reconstruct each leg independently.
Review all images before the patient leaves the scan table.
Anatomy cut-off? Reconstruct to include all anatomy.
Motion or positional changes detected? All anatomic areas must be reacquired in
their entirety.
Exam Archive and Transfer— Send all images to ConforMIS ASAP
Retain a permanent copy of the study. Retain the raw data for as long as possible.
Send ALL acquired data including the scout, images and dose page.
Send via ConforMIS secure web, cloud sharing networks, direct connection or
overnight priority shipping.

Protocol Build
We recommend building a ConforMIS protocol in
your CT scanner(s) with all of the appropriate
ranges
Table increment should not exceed slice thickness
KV/MaS Settings should be set at your standard
setting for each of the anatomic ranges to be
scanned. ConforMIS suggests employing dose
reduction techniques whenever possible.
All scans should be acquired in the helical/spiral
mode, rotation speed not less than 1sec, pitch as
close to 1:1 as possible, using the body filter
From the full leg scout the hip, knee and ankle
images may be acquired in a single scan acquisition
(alternatively these anatomic areas can be acquired
in separate series)
Provide reconstructed series in the coronal and
sagittal planes of the knee
Send all images that are acquired including the
scout and dose page if available*

Examples of Unacceptable Motion for ConforMIS
Protocol CT Scans

Protocol CT Scans
Multiple areas of
excessive motion

Protocol CT Scans
Motion is difficult to see on coronal
reconstruction image. It is essential to
review all series to detect motion.

Protocol CT Scans

Protocol CT Scans
The “wavy” appearance
evident on these
images indicates a
problem with table
motion. It can also
happen when the
gantry tilt is not at zero,
although it may read
zero. These issues
need to be addressed
before scanning
ConforMIS protocol
studies

Post Surgical Radiographic Assessment
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

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

APAcceptable positioning Poor positioning

LateralAcceptable positioning Poor positioning

Sunrise or Merchant ViewAcceptable positioning Poor positioning

Hip Anatomy
• Image and information from:
http://www.healthpages.org/anatomy-function/hip-structure-function-common-problems/
Hip
Ball (femoral head) and
socket joint (acetabulum)
joining the pelvis and femur
Acetabulum – composed of
the innominate bone which
includes the ilium, pubis,
and ishium forming the
socket into which the
femoral head fits
Ilium
Ischium
pubis

Hip Anatomy
Image from:
http://www.wikiradiography.net/page/Hip+Radiographic+Anatomy

Hip Anatomy
https://
www.studyblue.com/notes/note/n/practical-2-structure-set-2/deck/8022588
• http://www.healthpages.org/anatomy-function/hip-structure-function-common-problems
/
Cartilage
Labrum- The labrum is a
fibrocartilaginous structure
that outlines the acetabular
socket, usually triangular in
shape

Hip Anatomy
http://
mywwwzone.heckyeahllc.netdna-cdn.com/wp-content/uploads/2010/07/liofemoral-ligament.png
• http://www.healthpages.org/anatomy-function/hip-structure-function-
common-problems/
Ligaments
Iliofemoral ligament
-strongest ligament in the
body
Ischiofemoral ligaments
Pubofemoral
These ligaments
surround the hip joint
providing stability

Hip Anatomy
Hip motion is performed when several muscles act
simultaneously. Several muscles are responsible for each
directional motion. Some play a primary role in carrying out
the motion and others function in a secondary role.

Hip Anatomy
Muscles of the Hip – allow for movement, most
contribute to more than one type of movement
Four Main Groups
 Gluteal group - gluteus maximus, gluteus medius, gluteus
minimus, and tensor fasciae latae.
 Adductor group - adductor brevis, adductor longus, adductor
magnus, pectineus, and gracilis
 Iliopsoas group - iliacus and psoas major
 Lateral rotator group - externus and internus obturators, the
piriformis, the superior and inferior gemelli, and the quadratus
femoris.
***The rectus femoris and satorius contribute to hip motion but
are generally considered as primarily knee muscles***

Hip Anatomy
• Image from:
https://en.wikipedia.org/wiki/Muscles_of_the_hip

Hip Anatomy
Hip Movement
Flexion - Bending
Extensions - Straightening
Abduction – Moving the leg outward away from the body
Adduction - Moving the leg outward away from the body
Medial rotation
Lateral rotation
Circumduction

Hip Anatomy
Flexion -
Iliopsoas group -
iliacus and psoas
major
Rectus femoris
Satorius
Tensor fascia latae
Pectineus
Adductors longus
and brevis
Gracilis
Extension -
Gluteus Maximus
Semitendinosus
Biceps Femoris
Semimembranosus

Hip Anatomy
Adduction -
Adductor brevis
Adductor magnus
Adductor longus
Adductor minumus
Pectineus
Gracilis
Obturator externus
Abduction –
Gluteus Medius
Gluteus Minimus
Tensor Fascia Latae

Hip Anatomy
Medial Rotation -
Gluteus medius
Gluteus minimus
Tensor fascia latae
Adductor brevis and
longus
Adductor magnus
Lateral Rotation -
Superior gemellus
Inferior gemellus
Obturator externus
Obturator internus
Quadratus femoris
Piriformis

Diagnostic Imaging
Hip anatomy and pathology is generally demonstrated using
Routine radiographs, CR/DR
CT with or without arthrogram contrast
MR with or without arthrogram contrast

Diagnostic Imaging
CR – Protocol variable by site but
generally
AP
Full pelvis - usually for
the initial evaluation
Affected hip only –
subsequent evaluations
Lateral
Demonstrates
Joint narrowing
Sclerosis
Osteophytes
Bone cysts

Diagnostic Imaging
AP – Full Pelvis - Position the central ray at the mid point between syphysis pubis and ASIS.
Internally rotate the patients foot 15o
to 20o
. Ensure there is no rotation.
Image from: https://www.dreamstime.com/photos-
images/medical-xray-spine-pelvis.html

Diagnostic Imaging
AP – Unilateral - Position the central ray perpendicular to the femoral neck in question, at the mid
point between syphysis pubis and ASIS over head of femur. Internally rotate the patients foot 15o
to
20o
. Ensure there is no rotation.
Image from : https://www.google.com/search?
q=Hip+Radiograph&biw=1920&bih=897&source=lnms&tbm=isch
&sa=X&ved=0ahUKEwjR56vUi7fOAhUCSBQKHW1jDXIQ_AUIB
igB#imgrc=VwiKQMXwndKEaM%3A

Diagnostic Imaging
AP oblique– Demonstrates the lateral aspects of the femoral head and trochanters. Patients hips
and knees are flexed 90o
with the feet up, soles facing or touching if possible, and the knees abducted
45
o
(frog leg). The CR should be placed between the ASIS and the pubic symphysis angled cephalad 10-
15
o
. For unilateral imaging center on the affected acetabulum.
Information and
image from:
http://cdn.auntminnie.
com/user/documents/
content_documents/X
-
Ray_Patient_Position
ing_Manual_080402.
pdf

Diagnostic Imaging
CT
Demonstrates
Joint space narrowing
Sclerosis
Osteophyte formations
Reconstructions
Axial
Sagittal
Coronal images
CT Arthrogram
The use of diluted contrast in joint
delineates articular cartilage and
ligaments and some soft tissue
structures
MR
Demonstrates
Grade articular cartilage damage
Ligaments integrity
Meniscal tears
*Hip MR protocols vary from site to site and can
be dependent on the system used to acquire the
images*

Osteoarthritis (OA)

Osteoarthritis
Image from:
http://www.parkclinic.com.au/home/conditions-treatment/hip/hip-
osteoarthritis/

Grading Hip Osteoarthritis (OA)
Radiographic Assessment
Grade 0 - Normal
Grade 1 – Possible joint space narrowing and small
osteophytes
Grade 2 – Joint space narrowing, small osteophytes,
sclerosis in acetabulum
Grade 3 – Marked joint space narrowing, small
osteophytes, sclerosis and cysts, with deformity of the
femoral head and acetabulum
Grade 4 – Extreme joint space narrowing, bone on
bone, large osteophytes and severe deformities

Osteoarthritis CT Images
Sclerosis
Osteophyte
Cysts
Joint space na

Sclerosis
Osteophyte
Cysts

Femoral head deformity
Osteophyte
Cysts
Sclerosis

Surgical Treatment of Hip OA
Patients requiring hip arthroplasty
have moderate to severe arthritis in
the hip, including osteoarthritis,
rheumatoid arthritis or post-traumatic
arthritis, that causes pain and/or
interferes with daily living

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; Approximately 15% of hip
arthroplasties annually in the US are revisions

 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.
 Osteotomy – Acetabular bone cuts are made to realign the hip to a more natural
position
 Varus Rotational Osteotomy (VRO) – Corrects femoral neck valgus anatomy (too straight)
 Pelvic Osteotomy – Addresses acetabular deformities
 Total Hip Arthroplasty – involves the removal of the femoral head and damaged
surface of the acetabulum. The replacement implant consists of a metal or
ceramic ball (replaces femoral head) on a femoral stem , a metal socket (replaces
the acetabulum) and a liner between the ball and socket to provide a gliding
surface.

 CR images – AP, Lateral, Frog lateral and or cross table lateral 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.
 AP and Lateral – Must include full femoral stem and cement. Assess for component
loosening, stem failure and infection
 Frog lateral – Evaluate the proximal portion of the femoral component
 Cross table lateral – Evaluate the position of the acetabular component and the
integrity of the surrounding osseous structures
 Weight bearing or push pull views – Demonstrates implant loosening or component
wear
 Full leg – Determine leg length differences

The osteoarthritic knee and hip 2016

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