Lecture 4 and 5: Metabolic conditions, Suppurative OM and Non Suppurative OM Flashcards
What is a brodies abscess?
Clinical:
Localized, aborted form of suppurative osteomyelitis.
Mimics osteoid osteoma with localized limb pain, worse at night, dramatically relieved by aspirin.
History of recent infection or surgery (dental).
Most common in male children.
Metaphysis in long bone usually distal and prox. tibia, distal femur, fibula and radius.
What does a brodies abscess look like radiologically?
- Usually oval, elliptical with a halo or doughnut rim of heavy reactive sclerosis.
- Radiolucency usually 1cm or larger. (osteoid osteoma smaller)
- Osteoid osteoma and Brodies abscess cannot be determined radiologically.
What is vascuum phenomenon?
Vacuum phenomena involving the intervertebral discs are a result of accumulation of gas (principally nitrogen) within the crevices of the intervertebral discs or adjacent vertebrae.
Suppurative osteomyelitis on xray:
Latent period
Soft tissue
Bone destruction
Periosteal response
Spinal lesions
Latent period:
- no signs on xray
- extremity infections (10 days)
- spinal infections (21 days)
Soft tissue signs:
- within 3 days of infection
- deep ST swelling
- harder to detect in adults until swelling causes a soft tissue mass
Bone Destruction:
- Moth eaten or permeative
- Metaphyseal lesion usually dismminates to epiphysis or diaphysis
- May lead to joint invasion (either in 1st year of life or after physis closure)
- Over time = osteopenia and moth eaten lesion with sclerotic rim and sclerotic sequestrum
- Cortical disruption
Periosteal response:
- Laminated pattern of new bone formation common in kids and infants
- Codmans triangle
- New bone production = may create large involucrum (which is less dense than the sequestrum).
Suppurrative osteomyelitis: spinal lesions
Children and adolescence:
- Still have vascular channels to disc.
- Disc infection caused disc narrowing.
- Paraspinal oedema (abscess)
- End plate destruction
- Patchy lytic destruction throughout vertebral body
Adults:
- Vascular channels to endplate but disc is avascular.
- Infection usually in anterior subchondral endplate.
- Localised area of lucency and irregularity just beneath endplate.
- Vertebral destruction progresses. Collapse ensues.
- Para vertebral swelling; widened retropharyngeal space, retrotracheal space, displayed paraspinal lines. Lumbar or psoas abscess.
Tubercular Spondylitis (pott’s Dx.):
21 day latent period before plain film can detect bone lesions.
Earliest sign: Lytic destruction in anterior corner of endplate; some loss of disc space.
AP projection can show abscess formation
Tx: dense paraspinal mass overlying lucent lung
TL: soft tissue swelling into psoas shadow, often around a focus of vertebral destruction; opaque mass often pear shaped, frequently calcified.
See vertebral collapse and loss of disc space.
- Gibbus deformity: Acutely angulated flexion deformity, usually thoracic.
- Long vertebrae: Seen in young patients with open growth plates. Proceeds a long standing Gibbus deformity.
Vertical elongation of sub adjacent vertebral body (reaction to chronic infection).
Occurs without infection in quadriplegic patients know as a tall vertebrae.
Osteomalacia/rickets radiological features;
- General decrease in bone density with coarsened trabecular pattern (looks mottled).
- Cortical thinning
- Pseudofractures common at femoral neck, pubis, ribs and scapula.
- May see deformities in weight bearing bones as inferior sacral displacement, protrusio acetabuli, bowing of femur and tibia or a Kyphoscoliosis.
Acromegaly radiological features
- Thickened heel pad (>20mm suggests acromegaly)
- Skull see sella turcia enlargement, sinus enlargement and occipital overgrowth.
- Jaw see malocclusions and widened mandibular angle.
- Hands show widened phalangeal and metacarpal shafts.
- Spine see premature DJD, widened disc heights, thickened lamina and articular processes.
Fibrous dysplasia radiological features
Varied radiographic appearance
Plain radiograph:
- Ground-glass or smoky matrix
- May be completely lucent (cystic) or sclerotic
- Well circumscribed lesions often with sclerotic borders
- No periosteal reaction
- Can see bone expansion with widening of medullary canal
- Endosteal thinning and scalloping occur.
Pelvis and ribs: Most common site of monostotic fibrous dysplasia. FD is the most common cause of a benign expansile lesion. See bubbly cystic lesions, fusiform enlargement of ribs, protrusio acetabuli.
Extremities: Premature fusion of growth plates leading to short stature, bowing deformities, discrepant limb length.
CT: well-defined borders, expansion of the bone, with intact overlying bone, endosteal scalloping may be seen,
Pagets radiological features
Stage 1: osteolytic, destructive phase.
Stage 2: combined, mixed, or biphasic stage.
Stage 3: sclerotic or ivory stage.
Stage 4: malignant degeneration (osteosarcoma)
General features seen on X-ray will depend on stage in which bone is at. See density changes, coarsened trabeculae, cortical thickening, bone expansion, pseudofractures, bowing deformities, path fractures. In spine may see ivory vertebrae, picture frame vertebrae (appears squared off).
Sabre deformity of tibia = pseudofractures and anterior bowing
What are the 4 forms of spread for sup OM
1) Haematogenous spread: Most common. Represents a deposition into the blood stream of organisms that may reach distant skeletal sites.
2) Spread from a contiguous source of infection: Can extend into bone from adjacent contaminated site. Cutaneous, sinus, and dental infections are common sites of origin for OM.
3) Direct: Usually occurs as a result of direct penetrating injuries or puncture wounds, such as a nail, splinter or glass (most common in feet). Open fractures are an additional source of direct implantation.
4) Postoperative infection: Contamination of surgical sites
What is the usual location for sup OM:
Extremities:
- Usually metaphysis, may disseminate to diaphysis or epiphysis
- Most common in large tubular bone: femur most common then tibia, humerus, radius
Spine:
- Initial site in kids = disc
- Initial site in adults = anterior vertebral endplate
- Lx first, the Tx then Cx
- May not show for weeks
What are the 3 main features in sup OM
Sequestrum: Formation occurs. Dead bone from medullary and cortical infarcts “set Apart” from normal bone (osteoclasts remove smaller sequestered fragments, but larger fragments may require surgical removal).
As pus forms it lifts the periosteum, causing new bone proliferation and pain.
Involucrum: Periosteal new bone is attempt of body to wall of infection. This bony collar known as Involucrum (Latin to warp). Envelopes affected segment of shaft and in case of extensive lesions may cover almost entire shaft.
Cloaca: A defect in the involucrum though which inflammatory products drain; most commonly seen in chronic and antibiotic resistant osteomyelitis.
Empyema necessitatis: Discharge or decompression of inflammatory products via the Cloaca.
Describe this shit
Cortical destruction
Sequestrum
Moth eaten appearance
Solid periosteal response
Involucrum
What are the typical sites for pagets?
Pelvis
Sacrum
Femur
Skull
Tibia
Vertebra
What condition is this?
Pagets - osteolytic stage
What condition is this?
Pagets - biphasic stage
What condition is this?
Pagets - biphasic stage
What condition is this?
Pagets - sclerotic stage
What condition is this?
Pagets - metastatic stage
What condition presents with this appearance? Describe the appearance
Pagets
Cotton wool appearance
What is this condition? Describe the lesion
Ground-glass or smoky matrix
Lucent (cystic) or sclerotic
Well circumscribed lesions often with sclerotic borders, no periosteal reaction
Can see bone expansion with widening of medullary canal, endosteal thinning and scalloping occur.
See bubbly cystic lesions
What is this condition?
Polystotic fibrous dysplasia
