Musculoskeletal Imaging Study Materials

Musculoskel etal Imaging Trauma (fractures)    Definition: A break in the continuity of a bone or cartilage Classifications: o Closed fractures (simple): No communication with outside environment o Open fractures (compound): Communicates with outside environment (skin broken) Locations: o Neck  Subcapital  Transcervical o Intertrochanteric o Subtrochanteric shaft o Isolated greater or lesser trochanter Terms used for describing fracture positions      Angulation: refers to the degree of angular deformity caused by fracture fragments Displacement: change in the anatomical axis, are fragment in respect to another (i.e. side-to-side movement) Distraction: a separation of fragments that have been pulled apart Impaction: occurs when fragments driven together Foreshortening: occurs when fragments override each other Terms used in fracture follow-up      Position: Changed or unchanged Healing: Central or peripheral bony bridging (Remember clinical and radiographic healing is not the same) Delayed union: Healing process is slower than normal Non-union: Healing has stopped before union occurred Mal-union: Fracture has healed in unacceptable position Terms used in disruption of joints   Subluxation: An incomplete loss of contact between articular surfaces Dislocation: A complete loss of contact between articular surfaces Infection (osteomyelitis) Imaging of osteomyelitis    Plain films (changes may lag for 10-14 days) o Early changes: soft tissue swelling and periosteal reaction o Intermediate changes: bone destruction o Late changes: sequestrum formation, involucrum and bony sclerosis Nuclear Medicine o Increased uptake of tracer in bone scan and white cell scan o Higher sensitivity but other diseases, such as arthritis and soft tissue infection, can have same appearance Magnetic Resonance Imaging (MRI) o Highest sensitivity (best choice) – Excellent for demonstration of associated soft tissue infection Assessing patients with suspected osteomyelitis  If a patient presents with suspected osteomyelitis, it is usually not necessary to immediately administer the wide spectrum antibiotics, except if the infection is life threatening, e.g. where there is a risk of closing off the trachea. Needle biopsy of the area should be obtained in order to culture causative organism. Then initial broad-spectrum antibiotics can be started, followed by tailored antibiotic regimen once organism is isolated / sensitivity obtained. Arthritis  90+% of patients will have one of 3 main types: Osteoarthritis: affects mainly cartilage joint surface, Rheumatoid arthritis: affects mainly synovium with inflammation, and Gout: depositional arthritis due to (urate) crystals Imaging of osteoarthritis   Diagnosis by plain film for identification of: o Asymmetric joint space narrowing o Osteophytes – bone spurs o Degenerative cysts o Subchondral bone sclerosis CT and MRI may be useful in certain situations Imaging of rheumatoid arthritis   Diagnosis clinically, with plain film confirmation o Osteopenia – demineralisation of bone from increased blood flow due to inflammation. o Uniform joint space narrowing o Marginal erosions at joint margins o Subluxation (ligamentous of capsular laxity) MRI may be useful if there is cord compression. Tumours involving bone Imaging of tumours  Plain films are essential for assessing tumour characteristics, biological activity, cortical destruction, periosteal reaction. CT / MRI is better in evaluation of the lesion extent and soft tissue invasion and for following treatment response. Bone scan is helpful in identifying metastatic foci, as it is able to image the whole skeleton at one time Metabolic bone disease   Radiographic features: o Bone enlarged o Coarsened trabeculae o Whole bone evolved o Dense bone Mainly uses X-rays and/or bone scans.