msk
Table of Contents
Tumor Prevalence by Age
| AGE (years) | TUMOR |
|---|---|
| 1 | neuroblastoma |
| 1 - 10 | Ewing's of tubular bones |
| 10 - 30 | osteosarcoma, Ewing's of flat bones |
| 30 - 40 | reticulum cell sarcoma (Primary histiocytic lymphoma), fibrosarcoma |
| parosteal osteosarcoma, malignant giant cell tumor, lymphoma | |
| 40+ | metastatic carcinoma, multiple myeloma, chondrosarcoma |
Tumors by Location
Epiphyseal Lesions
- Giant Cell Tumor
- EG
- Infection
- Chondroblastoma (5-25 yrs old)
Arthritis Distribution in the Hand
Wrist
Arcs of Gilula
Carpal Bones
- Scaphoid axis
- The true axis of the scaphoid is the line through the midpoints of its proximal and distal poles. Since the midpoint of the proximal pole is often difficult to appreciate, an almost parallel line can be used that is traced along the most ventral points of the proximal and distal poles of the bone.
- Lunate axis
- The axis of the lunate runs through the midpoints of the convex proximal and concave distal joint surfaces and can best be drawn by finding the perpendicular to a line joining the distal palmar and dorsal borders of the bone as demonstrated.
- Scapholunate angle
- Normal: 30 - 60°
- Questionably abnormal: 60 - 80°
- Abnormal: > 80° (indicates instability of the wrist)
- Capitate axis
- The capitate axis joins the midportion of the proximal convexity of the third metacarpal and that of the proximal surface of the capitate.
- Capitolunate angle
- Normal: < 30°
- Abnormal: > 30° (indicates instability of the wrist)
DISI or dorsiflexion instability
- DISI is short for dorsal intercalated segmental instability
- The intercalated segment is the proximal carpal row identified by the lunate. The term 'intercalated segment' refers to it being the part in between the proximal segment of the wrist consisting of the radius and the ulna and the distal segment, represented by the distal carpal row and the metacarpals. In DISI or dorsiflexion instability the lunate is angulated dorsally.
- If you think lunate is tilted, measure the scapholunate and capitolunate angle.
VISI or volarflexion instability
- Volar intercalated segmental instability or palmar flexion instability is when the lunate is tilted too palmarly. Results in a scapholunate angle of < 30°.
- While most DISI is abnormal, in many cases VISI is a normal variant, especially if the wrist is very lax.
SLAC wrist
- Scapholunate advanced collapse (SLAC) refers to a specific pattern of osteoarthritis and subluxation which results from untreated chronic scapholunate dissociation (scapholunate ligament injury) or from scaphoid non-union (Scaphoid nonunion advanced collapse (SNAC). Other etiologies include Preiser disease (avascular necrosis of the scaphoid), midcarpal instability, intra-articular fractures involving the radioscaphoid or capitate-lunate joints, Kienböck disease, capitolunate degeneration, and inflammatory arthritis, such as seen in the crystalline deposition disorders of gout and calcium pyrophosphate dihydrate deposition disease (CPPD). The radiographic findings of arthropathy in SLAC wrist are nearly identical to those occurring in CPPD.
- Wrist radiographs reveal radioscaphoid joint narrowing, sclerosis, osteophytes, cysts, scapholunate dislocation, and carpal collapse. In SLAC secondary to scapholunate dissociation, increased distance between the scaphoid and lunate as well as lunate ulnar translocation will be obvious. A lateral view can show an increase in the scapholunate angle with a dorsiflexion of the lunate (dorsal intercalated segment instability - DISI deformity).
- Staging:
- Stage 1 A: Narrowing of the radioscaphoid joint first begins at the radial styloid aspect
- Stage 1 B: The rest of the radioscaphoid joint is narrowed (the entire scaphoid fossa is involved).
- Stage 2: The capitolunate joint is additionally narrowed and sclerotic. This results in a radial or dorsal radial position of the capitate (midcarpal SLAC).
Scoliosis
DDx
- congenital (secondary to vertebral anomalies, which may have associated tethered cord or diastematomyelia)
- neuromuscular
- diseases of collagen synthesis
- neurofibromatosis
- tumors (especially osteoid osteoma)
- radiation injury
Vertebral Anomalies Causing Scoliosis
DDx of Soft Tissue Calcifications
| Cause | Typical Appearance | Prevalence |
|---|---|---|
| Dystrophic | small to large amorphous Ca++ in the damaged tissue – may progress to ossification (formation of cortex and medullary space are then seen) | 95 - 98 % |
| CPPD | chondrocalcinosis; occasionally associated with calcifications in the soft tissues of the spine | 1 - 2 % |
| Metastatic calcification | finely speckled Ca++ throughout soft tissues | 1 - 2 % |
| Tumoral calcinosis | big globs of Ca++, usually near a joint | << 1 % |
| Metastatic osteosarcoma | amorphous, fluffy, confluent collection of Ca++ | <<< 1 % |
| Primary soft tissue osteosarcoma | amorphous, fluffy, confluent collection of Ca++ | <<<< 1 % |
DDx Periostial Reaction
- Hypertrophic Osteoarthropathy
- Thyroid Acropachy
- Hypervitaminosis A
- Fluorosis
- Infection
- Child Abuse
- Caffey's
- SAPHO
- Synovitis
- Acne
- Pustulosis (skin)
- Hyperostosis
- Osteitis
DDx Acroosteolysis
- Psoriasis
- Scleroderma/Raynaud's
- Diabetes
- Hyperparathyroid
- Frostbite
- Sarcoidosis
- Leprosy
- Occupational exposures (polyvinyl chloride)
- Post-traumatic
- Congenital (Hajdu-Cheney)
- Progeria
- Pyknodysostosis
- Lesch-Nyhan
DDx Vertebra Plana (FETISH)
- Fracture
- EG
- Tumor (leukemia,NB)
- Infection
- Steroids
- Hemangioma
Causes of AVN
- Trauma
- Steroids
- Sickle Cell
- Collagen Vascular Disease
- Chronic Renal Disease
- Asprin
- Alcohol
- Caisson Disease
Stages of AVN
| Stage | Findings |
|---|---|
| 0 | asymptomatic, normal radiographs |
| I | normal radiographs (abnormal MRI) |
| II | radiolucency and sclerosis |
| III | crescent sign, normal contour |
| IV | subchondral collapse, flattening |
| V | degenerative joint disease |
Trevor-Fairbanks Disease
- Intraarticular osteochondromas arising from the epiphysis
- May occur in single or multiple epiphyses and generally is found on only one side of the body
- Knee and the ankle are the most common sites
- Histologically identical to an exostosis
Cystic Soft Tissue Tumors
- Ganglion Cyst
- Synovial Cyst
- Cystic Schwannoma
- Synovial Sarcoma
- Mucoid Liposarcoma
- Myxomatous Tumors
Paget's Degenerates Into
- MFH
- Osteosarcoma
- Giant Cell
McCune-Albright
- precocious puberty
- cafe-au-lait spots
- polyostotic fibrous dysplasia
Mazabraud Syndrome
- Association of soft tissue myxomas and polyostotic fibrous dysplasia
Common Locations for Insufficiency Fractures
- Sacrum
- Femoral Neck
- Pubic Rami
- Spine
Soft Tissue Calcifications in the Hand
- Scleroderma
- Gout
- Giant Cell Tumor of Tendon Sheath
Arthritis w/ SI Involvement
- Ankylosing Spondylitis/IBD
- symmetric SI involvement
- thin, vertical, anterior syndesmophytes
- Reiters/Psoriatic
- asymmetric SI involvement
- asymmetric, bulky, noncontiguous syndesmophytes
Ivory Vertebrae
- Lymphoma
- Paget's
- Sclerotic Met
AC Separation
- Grade I
- Minor sprains with normal radiographs
- Grade II
- Moderate ligament sprains with acromioclavicular ligament disruption and demonstrable subluxation on stress views
- Grade III
- Disruption of the acromioclavicular and coracoclavicular ligaments with widening and dislocation of the joint
Acromion Types
DDx Deep Muscle Edema
- Deep venous thrombosis
- Rhabdomyolysis
- Myositis
- Infection
- Chronic repetitive injury
- Acute injury
- Acute or subacute denervation
Pes Anserine Bursitis
- pes anserine bursa is proximal and medial to the primary attachment of the medial hamstrings on the proximal tibia
- medial hamstrings that form the roof of the pes anserine bursa are the sartorius, gracilis, and semitendinosus (SGT)
Soft Tissue Tumors of Hand
- Ganglion cyst
- 60% of tumor cases
- Mucoid cyst
- dorsal to DIP joint
- Lipoma
- Hemangioma
- Glomus tumor
- subungual or palmar aspect of hand
- Epidermoid cyst
- distal finger
- Neuromas
- well-defined, high intensity on T2WI, and low intensity on T1
- digital nerves course along the lateral and medial aspects of the finger
- Giant Cell Tumor of tendon sheath
- low intensity on T2WI due to hemosiderin
- along the volar or dorsal aspect of the tendon sheath
Charcot Joint
- 5 “D’s”
- Density → increased or normal
- Distension → effusion
- Debris → bone fragments
- Disorganization
- Dislocation
- 40% of Charcot is the primary atrophic type in which you don’t have the 4 D’s, just resorption of bone
- Etiology → secondary to loss of pain perception and altered sympathetic control of blood flow
- diabetes
- alcoholism
- nerve/spinal cord injury
- polio
- neurosyphilis
- syrinx
- myelomeningocele
- steroids
- scleroderma
Charcot Spine
- usually secondary to tabes dorsalis or syrinx
- increased density, deformity, fragmentation, and dislocation
- destruction usually involves the intervertebral disc as well as the vertebral body
Sinus Tarsi Syndrome
- Associated with inversion injury and PTT dysfunction/pes planus
Calcaneal Pitch
- A line is drawn from the plantar-most surface of the calcaneus to the inferior border of the distal articular surface. The angle made between this line and the transverse plane (or the line from the plantar surface of the calcaneus to the inferior surface of the 5th metatarsal head) is the calcaneal pitch. A decreased calcaneal pitch is consistent with pes planus.
- 18 to 20° is generally considered normal, although measurements ranging from 17 to 32° have been reported to be normal.
Hallux Valgus
- Intermetatarsal Angle (IMA)
- Normal < 10 degrees
- Hallux Valgus Angle
- Normal < 15-18 degrees
- When the valgus angle of the 1st MTP joint > 30-35 deg, pronation of the great toe results and other structures are also affected
- Sesamoids
- Moderate subluxation
- lateral sesamoid is uncovered 50 to 75 % within 1st IM space
- medial sesamoid is located in a central position plantar to the first metatarsal head
- Severe subluxation
- lateral sesamoid moves to the lateral aspect of the first metatarsal head is dorsal to the medial sesamoid
Lisfranc Ligaments
- C1 = Medial cuneiform
- M2 = 2nd metatarsal base
- M3 = 3rd metatarsal base
- Red = dorsal Lisfranc ligament
- Blue = interosseous Lisfranc ligament
- Green = plantar Lisfranc ligament
Patella Alta
Insall-Salvati Ratio
- ratio of the patella tendon length (TL) to the length of the patella (PL). This can be measured on a lateral knee xray or sagittal MRI. Ideally the knee is 30 degrees flexed.
- The traditional number used to TL:PL is < 1.2 (between 0.8 and 1.2), although more recent literature 2 suggests that the true range of normal is more forgiving - up to 0.74 to 1.50.
- Patellar length (PL) is the greatest pole - pole length
- Patellar tendon length (TL) is defined as the length of the post surface of the tendon from the lower pole of patella to its insertion on the tibia.
- patella alta : > 1.2 (>1.5)
- patella baja : < 0.8 (<0.74)
Modified Insall-Salvati Ratio
- Also applied on a lateral 30 degree flexed knee radiograph. Measures distance from inferior margin of patella articular surface to the patella tendon insertion and compares this to the length of the patella articular surface (see diagram). Normal mean of 1.25. Ratio more than 2 is diagnostic of patella alta.
Mnemonics
Dense Bones (3M's PROOF)
- Mets
- Myelofibrosis
- Mastocytosis
- Sickle Cell
- Pyknodysostosis
- Renal Osteodystrophy
- Osteopetrosis
- Others
- Fluorosis
DDx Multiple Lucent Bone Lesions (FEMHI)
- Fibrous Dysplasia
- Metastasis / Myeloma
- Hyperparathyroidism (brown tumors) / Hemangioma
- Infection
- Eosinophilic Granuloma / Enchondroma
MSK Interventional
Shoulder Arthrogram
- Use 22 G spinal needle
- MR Arthrogram:
- Inject 12 cc of a solution of 5 cc normal saline, 5 cc Omnipaque 300, 10 cc 1% lidocaine, and 0.1 cc gadolinium
- CT Arthrogram:
- Inject 12 cc of a solution of 5 cc normal saline, 10 cc Omnipaque 300, and 5 cc 1% lidocaine
msk.txt · Last modified: 2024/07/16 15:47 by 127.0.0.1