NONTRAUMA
ARTHRITIS
RSNA ARTHRITIS DEGENERATIVE CONDITIONS.pdfRSNA ARTHRITIS INFLAMMATORY CONDITIONS.pdfHallmark of arthritis is cartilage destruction, evident on xray as joint space narrowing.
Broad categories:
Degenerative (OA)
Inflammatory: RA, spondyloarthropathies, juvenile idiopathic arthritis
Crystal deposition: gout, CPPD, hydroxyapatite
Hematologic: hemophilia
Metabolic
OSTEOARTHRITIS / OA
Altered local mechanical factors in a susceptible individual resulting in break down of articular cartilage, bone, ligaments, menisci, joint capsule, synovium and mm.
MCC of cartilage loss in the middle-aged and older population.
When in younger patients or unusual location such as shoulder, elbow or ankle then there is usually prior trauma or other underlying arthritis.
Involves weight-bearing joints and the hands in a specific distribution.
Radiograph & CT
Osteophytes
Subchondral cystic change: 2/2 herniation of joint fluid into bone through a cartilage defect.
Sclerosis of subchondral bone: 2/2 reactive remodeling.
Lack of periarticular osteopenia
MRI findings
Osteophytes
Subchondral cystic change
Subchondral edema 2/2 inflammatory and reactive changes.
Synovitis w thickened, irregular, and hyperenhancing synovium
Joint space narrowing is present in all arthritides.
OA can be diagnosed w confidence when subchondral sclerosis, osteophytes, and subchondral cystic changes are present + absence of erosions and periarticular osteopenia.
HAND
Decreasing order of sites involved:
DIPs
first carpometacarpal joint
PIPs
The metacarpophalangeal joints (MCPS) are less commonly affected, unlike RA.
Large osteophytes cause characteristic ST swelling
DIP: Heberden nodes
PIP: Bouchard nodes
Erosive OA:
Typically affects elderly females w combo of clinical findings of RA w findings and distribution more similar to conventional OA.
Distribution is limited to hands and MC involves the DIPS.
Gull-wing appearance of DIP joint 2/2 central erosion and marginal osteophytes.
SHOULDER
Grashey view (obtained posteriorly in 40 degrees obliqued external rotation) shows the glenohumeral joint in profile and best demonstrates cartilage space narrowing.
FOOT
MC joint affected by OA is the metatarsophalangeal joint (MTP) of the great toe which can lead to hallux rigidus (stiff big toe)
OA also affects the talonavicular joint and causes dorsal beaking.
KNEE
3 joint compartments of the knee:
Medial and lateral tibiofemoral compartment
Patellofemoral compartment
Typical pattern for OA of the knee is asymmetrical involvement of the medial tibiofemoral compartment. If severe, can involve all 3 compartments.
Osteophytes determine if OA is present. Degree of joint space narrowing determines the severity of OA.
Degree of tibiofemoral cartilage space narrowing is best determined on standing weight-bearing views, often on standing films in slight flexion.
Bilateral involvement of knees is typical.
HIP
In addition to the typical features of OA, hip OA also features characteristic superolateral cartilage space narrowing. Less commonly, medial or axial (concentric) cartilage space loss can be seen in hip OA.
Axial cartilage space loss is the typical pattern in RA; however, since OA is far more common than RA, axial cartilage space narrowing w osteophytes is more likely to represent OA rather than RA. If axial cartilage space loss is seen w/o osteophytes, RA is more likely.
SPINE
Vertebral body-disc articulations are cartilaginous joints. There are 3 components:
Annulus fibrosus + nucleus pulposus = together make disc
Cartilaginous endplates (hyaline cartilage analogous to articular cartilage in other joints)
OA affects synovial joints and can occur at the facet (zygapophyseal), atlantoaxial, uncovertebral joints (C spine C3-7), costovertebral and sacroiliac joints.
The spectrum of intervertebral disc (IVD) and endplate degeneration is characterized by dessication and eventual collapse of the IVDs, endplate sclerosis and remodeling, and osteophyte formation.
Chronic response to injury rather than an acquired disease.
Discovertebral degeneration (DVD) is more accurate than the informal phrase DDD.
Gas in the IVD (vacuum phenomenon) is commonly seen and is pathognomonic for degenerative change.
Dont confuse it with Kummell dz which is gas w/n vertebral body compression fx representing osteonecrosis.
Complications of DVD: spinal stenosis, neural foraminal stenosis and degenerative spondylolisthesis.
Diffuse idiopathic skeletal hyperostosis (DISH): flowing bridging anterior osteophytes spanning at least 4 vertebral levels, with normal disc spaces and sacroiliac joints.
Etiology is unknown; occurs in elderly
Usually asx but may cause dysphagia when affecting C spine.
Associated w/ ossification of the PLL which may be a cause of spinal stenosis. OPLL may be difficult to identify on MRI and best seen on CT.