Soft tissue and bone Flashcards
This 71-year-old female had a fall at home and fractured her left neck of femur. She was admitted to hospital, where she underwent an operation to fix the fracture. She developed a postoperative pneumonia and died a few days later. A few months earlier she had been admitted to hospital with a fractured humerus, which was put in a sling for stabilisation. On post-mortem examination she was also found to have a vertebral collapse fracture and a healing fracture of the humerus was confirmed (see specimen).
What is the most likely underlying condition rendering this patient susceptible to multiple fractures
osteoporosis
How would you diagnose osteoporosis during life?
Radiological assessment of bone mineral density. Osteoporosis is defined as a bone mineral density measurement of two standard deviations below the mean value for young adults of the same sex.
Osteoporosis is clinically asymptomatic until it presents with fractures and deformity.
Where are the common sites for osteoporosis fractures?
- vertebral crush (collapse) fractures, which may result in loss of height and a stooping deformity
- fractures of the neck of the femur
- distal radius (Colle’s fracture).
What’s the term for a fracture in the distal radius?
Colles fracture
Risk factors for osteoporosis
- elderly women (oestrogen deficiency is a key association)
- steroid therapy and Cushing’s syndrome
- immobility
Prevention of osteoporosis
- oestrogen treatment in post-menopausal females (hormone replacement therapy)
- bisphosphonates reduce bone reabsorption
- regular exercise
- dietary calcium also have beneficial effects
What is a pathological fracture ? Do you know any other (apart from osteoporosis) conditions predisposing to fractures?
A pathological fracture is a fracture of bone weakened by disease and may occur after relatively little trauma or even spontaneously.
- tumours (e.g. metastatic bone deposits)
- osteoporosis
- osteomalacia
- Paget’s disease.
What would cause moth-eaten areas in the cortex of the bone?
Inflammation causing bony destruction
What causes osteomyelitis?
Local infection:
- penetrating trauma
- open fracture
- adjacent infection
- post surgery)
Haematogenous spread of bacteria
What are the complications of osteomyelitis?
It can result in haematogenous spread of bacteria to other sites or local spread of infection, e.g. to include the joint cavity and cause a septic arthritis.
- Septicaemia
- septic arthritis
- alteration in growth rate (particularly in infants with damage to the epiphyseal growth plate, and chronic osteomyelitis)
- in adults, acute osteomyelitis may become chronic and very difficult to treat. There may be infectious exacerbations with abscesses and discharging sinuses. There may be secondary amyloidosis and occasionally a squamous cell carcinoma may arise from a chronic sinus..
What’s the most common causitive organism of osteomyelitis?
Staphylococcus aureus
Patients with sickle cell disease are predisposed to develop Salmonella osteomyelitis.
What are the presenting features of acute osteomyelitis?
Typically the patient is unwell with a raised temperature and complains of severe pain and tenderness aggravated by any movement.
However, immunosuppressed patients frequently have few symptoms and signs.
How do you treat osteomyelitis?
If acute osteomyelitis is suspected blood cultures should be taken and large doses of intravenous antibiotics given immediately to avoid septicaemia. X-ray changes do not appear for several days and magnetic resonance imaging shows abnormal signal much earlier.
Which part of the bone does haematogenous osteomyelitis typically involve?
Typically the metaphysis of long bones is involved where dilated vascular sinusoids with sluggish blood flow provide an ideal site for multiplying bacteria. They pass into the marrow spaces and cause an acute inflammatory response. Pus spreads through the medullary cavity and the cortex. It may elevate the periosteum and form a subperiosteal abscess. It may tract into surrounding tissues and eventually reach the skin surface forming a chronic discharging sinus. Vascular thrombosis or compression leads to bone necrosis. Necrotic bone in osteomyelitis is known as sequestrum. Meanwhile cytokines activate osteoclasts causing bone destruction. Eventually, subperiosteal new bone may form an incomplete shell (involucrum) around the dead bone..
Where’s the metaphysis?
The metaphysis is the narrow portion of a long bone between the epiphysis and the diaphysis. It contains the growth plate, the part of the bone that grows during childhood and as it grows, it ossifies near the diaphysis and the epiphyses
Who gets osteomyelitis?
Acute haematogenous osteomyelitis classically affects children and adolescents. The primary focus may be a minor lesion elsewhere (e.g. a boil) but frequently no source is found.
What might a paget’s disease scull bone look like?
Marked thickening and prominent vascular grooves on the inner surface. The latter are due to enlarged blood vessels caused by an attempt to supply the large volume of very metabolically active bone, which is continuously remodelling.
What is the underlying pathology of Paget’s disease?
Paget’s disease is characterised by excessive turnover of bone with resulting disorganisation of the bony architecture. It may affect part or all of a bone, several or many bones.
The aetiology is uncertain.
There is a genetic predisposition and rarely single gene mutations may be causative (e.g. in the sequestosome 1 gene SQSTM1, which is also called P62).
Whic bones are most frequently affected by Paget’s disease?
- vertebrae
- pelvis
- skull
- femur
- tibia
- humerus
What are the clinical features of Paget’s disease?
A large number of patients with Paget’s disease may have no symptoms and the diagnosis is made incidentally on radiological imaging.
The most common complaints are bone pain and deformity. Even though the bone is thickened, it is structurally weak and may lead to bowing of long bones.
There may be frontal bossing due to thickening of the skull.
Pathological fractures may result from weakened bone:
- Osteoarthritis may result from abnormal stresses across joints due to bone deformity.
- Skull thickening may cause a narrowed exit foramen of the 8th cranial nerve and cause deafness.
- Enlargement or collapse of vertebrae may manifest with spinal cord compression.
- Rarely, patient’s with extensive Paget’s disease may develop high cardiac output failure due to increased blood flow through the affected bones.
Serious complication of Paget’s disease
Approximately 1% of patients develop a sarcoma arising in one of the bones affected, usually an osteosarcoma or a high grade undifferentiated sarcoma.
Common sites are the femur and humerus.
The prognosis is poor and many patients develop early pulmonary metastases.
What’s the diagnosis?
A humerus, the superior aspect of which is expanded by a tan / grey crumbly tumour. There is extensive infiltration of the central marrow cavity. Where the tumour bulges out it has destroyed some of the bone and extends into the overlying soft tissue.
osteosarcoma
What cell type forms an osteosarcoma?
malignant osteoid producing cells
What’s the most common malignant primary bone tumour?
- Myeloma
2. Osteosarcoma
