Imaging of the cartilage
and subchondral bones.
DR/ ABD ALLAH NAZEER. MD.
Definition: The cartilage covering the articular surfaces of the
bones forming a synovial joint. Also called arthrodial cartilage,
diarthrodial cartilage, investing cartilage.
Articular cartilage. A type of hyaline connective tissue that
covers the articulating surfaces of bones within synovial joints.
Cartilage. A specialized, fibrous connective tissue present in
adults, and forming most of the temporary skeleton in the
embryo, providing a model in which most of the bones develop,
and constituting an important part of the organism's growth
mechanism; the three most important types are hyaline
cartilage, elastic cartilage, and fibrocartilage. Also, a general
term for a mass of such tissue in a particular site in the body.
• CHONDROCYTES: (1‐2%)
• EXTRACELLULAR MATRIX:
Collagens‐Type II (15‐20%).
• draws water & maintains osmotic pressure
• counteracts swelling pressures
• provides force in tension & shear
• resists compression
Imaging modalities of articular cartilage disease.
Radiography have been the traditional imaging modality used to
evaluate patients with acute cartilage injury. However radiograph
can only assess joint space loss(Indirect imaging of cartilage) and
osteophytic formation and are insensitive for early cartilage
Arthrography and CT arthrography.
For this reason MRI is has become the imaging modality of choice
for evaluating articular cartilage, especially T2 mapping. Because
of its high resolution, multiplaner capabilities and excellent tissue
contrast, MRI can detect and characterize morphologic changes
associated with cartilage degeneration and acute cartilage injury.
Lack of exposure to ionizing radiation is an additional attractive
feature of MR imaging particularly in young patients.
Detecting biochemical or functional changes in cartilage is
Visualization in multiple planes.
Real time, dynamic assessment.
No radiation and in expensive.
But, no visualization of deep articular cartilage.
Low contrast between cartilage and fluid.
Low negative predictive value.
OA of the knee. Coronal ultrasound scans through the distal femur
of a normal knee (A) and an osteoarthritic knee (B) demonstrate
the intracondylar notch. The red arrows indicate the cortical surface
of the femur, and the yellow arrows indicate the superficial surface
of the cartilage. Note that compared with the normal knee, the
cartilage in the osteoarthritic knee is more echoic, there is loss of
definition of the margins, and it appears thinner laterally.
Tomographic technique :
High spatial resolution.
Acute traumatic injury.
More available than MRI.
Excellent to depict superficial cartilage damage.
(probably superior to MRI).
Very poor assessment for other articular structures.
No well validated for early intra-substance changes.
Correlation of CT arthrography and MR imaging. (A) Sagittal reformatted CT
arthrography of the medial knee compartment shows posterior horn meniscal
tear (arrow). Note superficial cartilage thinning at the femoral condyle
adjacent to the meniscus. (B) Sagittal proton density-weighted MR image of
the same knee demonstrates the posterior horn meniscal tear (arrow). (C)
Coronal reformatted CT arthrography of the medial compartment shows focal
cartilage defect in the central femoral condyle (arrow). (D) Coronal fat-
suppressed T2-weighted MR image shows the same defect (arrow).
Focal cartilage defect at CT arthrography and MRI Fat sat images.
The International Cartilage Repair Society has
set up an arthroscopic grading system by which
cartilage defects can be ranked:
grade 0: (normal) healthy cartilage
grade 1: the cartilage has a soft spot or blisters
grade 2: minor tears visible in the cartilage
grade 3: lesions have deep crevices (more than
50% of cartilage layer)
grade 4: the cartilage tear exposes the
underlying (subchondral) bone.
Chondromalacia can be divided into 4 grades by MRI, typically using fat
saturated proton density sequences. This grading system is the modified
outer bridge grading system, which was devised for arthroscopy initially for
assessment of chondromalacia patella, but then modified and extended for
all chondral surfaces.
Focal areas of hyperintensity with normal contour
arthroscopically : softening or swelling of cartilage.
Blister-like swelling/ fraying of articular cartilage extending to surface
arthroscopically : fragmentation and fissuring within soft areas of
Partial thickness cartilage loss with focal ulceration
arthroscopically : partial thickness cartilage loss with fibrillation (crab-
Full thickness cartilage loss with underlying bone reactive changes
arthroscopically : cartilage destruction with exposed subchondral bone.
• Assesses early cartilage damage as GAG loss
prior to development of macroscopic cartilage
• Negatively charged MRI contrast (Gadolinium;
Gd), (IV or intra‐articular) is repelled by
negatively charged GAG.
Less GAG in cartilage less negative charge
relative to normal cartilage. The more the
negatively charged contrast will penetrate
GAG deplete cartilage.
• Gd penetrates normal cartilage, high [GAG], in
a reciprocal manner.
↑ Gd ↓ T1 value (MRI property of Gd)
• Double negative:
↓*GAG+ = ↑Gd = ↓ T1
↑*GAG+ = ↓Gd = ↑T1
• *GAG+ is directly proportional to T1 value
• T1 value = T1 relaxation =me
= dGEMRIC index.
• IV Gd – double dose.
• Wait 30‐90min for penetration.
• IA be over than IV.
• T1 maps of cartilage.
• No difference between 1.5T & 3T (5).
• Excellent in vitro
• Higher dGEMRIC index
(less Gd , higher [GAG])
= higher resistance to
Color-coded T1ρ map overlays on SPGR images in the posterior
femoral cartilage. (a) a healthy volunteer, male, 30; (b) a patient
with early OA, female, 27. The T1ρ values were 40.05±11.43 ms
in the volunteer and 50.56±19.26 ms in the patient, respectively.
Case study of dGEMRIC as a function of time before and after PCL injury. A decline in the
dGEMRIC Index is apparent at one month, with a further decrease at three months and
recovery at six months. These data illustrate the potential for biochemical monitoring of
cartilage to demonstrate degeneration and recovery of the tissue from a traumatic
injury. Similar studies might be used to monitor cartilage status improvement with other
mechanical, surgical, or pharmaceutical interventions. (From Young AA, Stanwell P,
Williams A, et al. Glycosaminoglycan content of knee cartilage following posterior
cruciate ligament rupture demonstrated by delayed gadolinium-enhanced magnetic
resonance imaging of cartilage (dGEMRIC).
Mild diffuse increased intra-substance signal
within morphologically normal cartilage.
Transverse T2 weighted MR of
patella. Blister is seen at surface
of cartilage (arrow) suggestive
of grade 2 chondropathy.
Transverse T2 weighted MR of
patella. Crabmeat appearance is
apparent (arrow) compatible with
grade 2 chondropathy.
Thinning, fissuring or fibrillation involving depth < 50% over small area.
Transverse T2 weighted MR of patella. Focal
ulceration is seen (arrow) Grade 3 chondropathy.
Transverse (T2 fat sat)
weighted MR of patella. Focal
ulceration is seen (arrow)
Grade 3 chondropathy.
Thinning, fissuring or fibrillation involving depth > 50% over large area.
Transverse CT arthrographic image.
several patellar fissures are seen
extending to subchondral bone,
compatible with grade 4 chondropathy.
Transverse proton density weighted MR
with FS of patella. Fissures are seen (thin
arrows) extending to subchondral bone
compatible with grade 4 chondropathy.
Patchy subchondral edema is also
evident (bold white arrow).
Full thickness chondral lesion , exposed subchondral bone.
Various changes may be seen in the subchondral bone, and are
often associated with cartilage changes. Subchondral bony
changes can be described in more detail by grading
MR changes according to signal intensity or by assessment from a
morphological pattern. MR signal intensities usually are
compatible either with edematous changes or with sclerotic
changes. A small sclerotic focus of subchondral thickening of the
Cortex or a subchondral semilunar area is commonly seen in
degenerative disease. A cortical impaction, bowing fracture or a
subchondral branching fracture line can be seen in trauma and
may be accompanied by bone marrow edema. Geodes or cysts
may be seen in degenerative disease . Bone marrow edema is
non-specific and can be seen in degenerative disease or
traumatic injury . Osteophytes are a clear indication of
Sagittal STIR weighted MR. Subchondral patchy high signal
intensity consistent with edema (arrow) following ankle trauma.
T1 weighted MR (A) and STIR weighted MR (B) in tibial plateau specimen.
Thinning of cartilage is seen in A (white bold arrows) associated with
subchondral semilunar-shaped very low signal intensity (black arrows), and
larger area of mildly lowered signal intensity. In B larger area revels diffuse
patchy high signal intensity compatible with “edema”(arrow) surrounding
the semilunar area.
Coronal T1 weighted MR in knee trauma. Focal thickening of
cortical line (black arrow) and larger area of patchy subchondral
changes (white arrows). Note that this appearance could also
be seen in avascular necrosis.
Sagittal T2 weighted MR obtained following meniscectomy. In A (initially)
meniscal remnant is apparent (arrowhead),as well as diffuse patchy
subchondral changes (arrows).In (follow-up) B cortical impaction is
seen (curved arrow) and semilunar subchondral change (arrow).
Sagittal T2 weighted MR image. Note linear band of subchondral edema (long
arrow) and deeper foci of branching subchondral changes (short arrows).
Sagittal proton density weighted MR. Abnormal concavity of lateral
tibial plateau is seen (arrows) compatible with “bowing” fracture.
Transverse T2 weighted MR with FS. Marginal (bold arrows)
and central osteophytes (long thin arrow) are evident.
Coronally reconstructed CT image of ankle. Subchondral cysts (arrows)
and cartilage defect (arrowhead) are seen after ankle trauma.
Sagittal fat saturated T2. Degenerative disease with severe cartilage
thinning is apparent (arrows). Note subchondral edema (short arrow).
Most common benign skeletal tumor
20-50% of all benign bone tumors.
Most frequent in 1 1st and 2nd decade of life
Male : female = 1.5 : 1.
Most often in juxta -epiphyseal / metaphaseal.
area of long bones (distal femur, proximal tibia)
40% around the knee (also shoulder, hip).
Bony exostosis with cartilage cap.
Typically grow away from physis.
Growth ceases after maturity.
Growth after maturity indicates malignant
< 1% risk of malignant transformation for solitary lesions.
Painless bony mass.
Can be painful if mechanical irritation (nerves, vessels,
muscles, tendons, bones).
Sessile or stalk -like
Metaphyseal bone may be
expanded and remodeled.
Cartilage cap may be calcified.
Base of lesion contiguous
with cortex of bone.
Peak incidence in 3 3rd rd
Male : female = 1 : 1
Common in short tubular
bones of hands and feet
Most common primary
tumor in the hand,
usually in the diaphysis.
Hand > Foot lesions more commonly active.
Cortical bone erosion resulting in pain, bony mass,
or pathologic fracture.
Expansile lesions may cause palpable bony mass
Found incidentally in long bone .
< 1% risk of malignant transformation< transformation.
Most common in femur and humerus.
Tubular bone Diaphysis Matrix – “popcorn ”
“comma shaped ”
Rare, benign tumor derived from chondroblasts
(5% of benign bone tumors)
Epiphysis of long bones (also apophyseal
Most common sites
Femur, humerus, tibia
Male : female = 3 : 2
Mean age: skeletally immature
May have behavior not normally associated
with benign tumors (pulmonary metastases,
local bone / soft tissue invasion).
Pain near a joint without history of trauma
Tumor can induce a secondary synovitis
Patient may have a joint effusion
Pathological fracture rare.
Lytic well-defined margins
Scalloping or erosion
of cortical bone may be present
Fine calcifications (punctate , rings).
Malignant tumor that produces cartilage matrix
Very uncommon, arises centrally in bone, found in
children found children Secondary chondrosarcoma
Secondary Arises from benign cartilage defects
(osteochondroma – surface , enchondroma -
Occurs in 5th or 6th
decade of life.
Male : female = 1.5 : 1
humerus, ribs, pelvis
Higher risk to occur in
patients with Ollier
disease and Maffucci
(3rd rd or 4th decade of