Approach to Bone Pain Flashcards
Common causes of bone pain?
Trauma, Tumour, Infection
What are insufficiency/fragility fractures?
Fractures by normal physiological stress applied on abnormal (weakened) bones
@spine, tib/fib, pelvis
predisposing factors: osteoporosis, corticosteroid therapy, post-irradiation
What is stress fracture?
Fracture resulting from abnormal stress on normal bone
What are the imaging findings on a stress fracture?
Linear sclerosis on radiograph
Focal periosteal reaction (new bone formation)
Types of fractures
- Hairline
- Linear
- Oblique Non-displaced
- Oblique Displaced
- Spiral
- Comminuted (broken at 3 or more sites)
- Segmental
Stages of Fracture Healing
- Hematoma forms between 2 ends of bone, creating fibrin mesh, which seals fracture site. Periosteum is stripped from bone surface.
- Traumatic inflammation: Migration of inflammatory cells and macrophages
- Demolition: Macrophage invades and phagocytose the hematoma and tissue debris
- Granulation tissue: neovascularization and fibroblasts from surrounding cells
- Callus formation (soft bone) occurs over weeks: Periosteal reaction - haphazard osteoid formation producing a woven bone
-> external callus: bridges fracture site outside bone
-> internal callus: bridges fracture in medullary cavity
=> callus is well established (by 3rd week) but still woven bone (mechanically weak) - Remodelling occurs over months: Organised osteoclastic and osteoblastic activity replacing woven bone with compact lamellar bone
Principles of NORMAL fracture healing
- Close apposition of fractured bone ends
- Immobilisation
- Adequate healing capacity
Causes of delayed and impaired fracture healing
- Poor apposition of fractured bone ends
- Poor blood supply
- Poor general nutritional status
- Foreign bodies or non-viable tissue
- Infection
- Conditions that suppress healing: Corticosteroids, immunosuppression, immunodeficiency
Complications of fracture
- Problems related to union of bones:
- delayed union
- mal-union (union with angulation)
- fibrous union (fibrous scar -> false joint)
- non-union - Infection (osteomyelitis, septic arthritis)
- Thrombosis and embolism
- Soft tissue injury
What is osteoporosis?
A condition where the bones are weakened to a point that they can break easily.
Treatment for osteoporosis
- Lifestyle and diet
- exercise
- calcium
- vitamin D - Antiresorptive Agents
- Bisphosphonates
- Denosumab
- Oestrogens
- Calcitonin - Anabolic Agents
- Romosozumab
- Parathyroid hormone therapies
How do bisphosphonates work?
Slow bone loss by increasing osteoclast cell death
- [ORAL] Risedronate, Alendronate (take on empty stomach with 240ml plain water, wait 30 mins before taking food)
- [IV] Zoledronic acid
Significant adverse effects of bisphosphonates & contraindications
Atypical femoral fractures
Hypocalcaemia
Severe bone, joint, muscle pain
Osteonecrosis of jaw
contraindications: pts with hypocalcaemia, pregnant
How does denosumab work?
Human monoclonal antibody against RANKL
Prevents development of osteoclasts
- subcutaneous injection every 6 months
- co-administer with calcium and vitamin D
Adverse effects of denosumab & contraindications
Bone, joint, muscle pain
GI effects
(atypical femur fractures, osteonecrosis of jaw uncommon)
Do NOT discontinue as may cause increased risk of spinal column fractures when discontinued
contraindications: pts with hypocalcaemia, pregnant
How does oestrogen work?
Oestrogen can help maintain bone density
- oestrogen therapy used for bone health in younger women or women whose other menopausal symptoms also requires treatment
- Raloxifene:
– selective oestrogen receptor modulator
– mixed oestrogen receptor agonism and antagonism
– mimics effects of oestrogen on bone density in postmenopausal women
– reduces risk of breast cancer
– increases risk of blood clots and hot flashes
Adverse effects of oestrogen therapy
increases risk of breast cancer and blood clots which can cause stroke
How does calcitonin work?
Calcitonin is a peptide hormone secreted by parafollicular cells of the thyroid gland
Calcitonin reduces blood calcium levels, opposing effects of parathyroid hormone
Inhibits osteoclastic bone resorption
IV, SC, IM injection or nasal spray
Adverse effects and contraindications of calcitonin
Red streaks on skin
Injection site reaction (redness, warmth)
contraindications: hypocalcaemia, hypersensitivity
How does Romosozumab work?
Humanised mouse monoclonal antibody against sclerostin
Removes sclerostin inhibition of the canonical Wnt signalling pathway that regulates bone growth
-> increases bone formation and decreases bone resorption
- SC injection once monthly for 12 months
Adverse effects and contraindications of romosozumab
MI, increased risk of CV death, stroke
contraindications: hypersensitivity, hypocalcaemia, history of MI or stroke
How do parathyroid hormone therapies work?
Teriparatide
Stimulates new bone formation and increase bone strength
- once daily SC injection (max treatment 24 months)
Adverse effects and contraindications of parathyroid hormone therapies
Calciphylaxis, hypercalcaemia
contraindication: hypersensitivity, pre-existing hypercalcaemia, renal impairment, pregnancy
Primary vs Secondary bone tumours
Primary bone tumours
- uncommon
Metastasis
- common
What are some Benign Primary Tumours?
- Exostosis/Osteochondroma
- Enchondroma
- Simple Bone Cyst
- Osteoid osteoma
What is osteochondroma/exostosis?
- most common benign bone tumour that arises near end of long bone
- benign cartilage-capped tumour that is attached to the underlying skeleton by a bony stalk
- usually solitary
What is enchondroma?
- benign cartilaginous tumour that arises from diaphyseal medullary cavity
- painless swelling
- usually occurs at small bones eg phalanges of hands
imaging features:
- stippled, flocculent calcifications
- bulbous expansion
histological features:
- mature hyaline cartilage
- no cytological atypia
- no permeation of bone trabeculae or marrow invasion
- no invasion of soft tissue
What is simple bone cyst?
- occurs in metaphysis
- occurs in young child
- benign, fluid containing lesion
- cyst-like structure with fibrous wall
- amorphous pink material with a cementum-like appearance
What is osteoid osteoma/osteoblastoma?
- benign bone forming tumour characterised by extensive reaction and pain disproportionate to size
- more common in young males
radiographic appearance:
- oval lytic lesion located within cortical bone
- sclerosis may obscure underlying lytic nidus on radiograph
- +/- central sclerotic focus within nidus
CT imaging:
- calcified nidus
- reactive periosteal/cortical thickening
histological appearance:
- anastomosing woven bone trabeculae rimmed by abundant osteoblasts
- loose and vascular intratrabecular spaces
- no malignant features (ie. atypia, malignant osteoid, invasion)
What are some of the malignant primary bone tumours?
- Ewing’s sarcoma (occurs in very young pts in the paediatrics age group)
- Osteosarcoma (occurs in teenagers to young adults)
- Chondrosarcoma (occurs in elderly patients)
Look at patient’s age!
What are the features of osteosarcoma?
KEY features:
- BONE FORMING tumour
- Malignant histological features:
-> malignant tumour cells (ie. pleomorphic, cytological atypia, hyperchromatic nuclei)
-> malignant lace-like pattern of osteoid
-> invasive growth pattern
-> tumour necrosis
- Metastasise to lungs
other features:
- occurs in teenagers to young adults
- can be a sclerotic lesion
- classic sunburst periosteal reaction (seen in radiograph)
- occurs at metaphysis of long bones
- arises from the medullary cavity and extends to cortex
- fleshy appearance with necrosis and haemorrhage
What are the features of chondrosarcoma?
- malignant bone tumour that produces cartilaginous matrix
- cytological atypia
- permeation of bone trabeculae
- locally aggressive tumour that invades surrounding bone and soft tissue
- large lobulated tumour, pearly white or light blue, with focal calcification
Difference between enchondroma and chondrosarcoma
Enchondroma:
- mature hyaline cartilage
- no cytological atypia
- no permeation of bone trabeculae
- no soft tissue or marrow invasion
Chondrosarcoma:
- malignant tumour that produces cartilaginous matrix
- cytological atypia
- permeation of trabeculae
- soft tissue and marrow invasion
What are the features of Ewing’s Sarcoma?
- permeative destruction
- saucerisation defect
- onion skin periosteal reaction
due to translocation t(11,22)(q24;q12)
What modalities can be used in secondary bone tumour/metastasis?
- MRI
- Bone scan
- Plain film
What is Osteomyelitis?
Infection of bone that involves bone cortex, medulla and periosteum
- main causative agents:
staph aureus
e. coli
streptococci
h. influenzae
salmonella
mycobacterial tuberculosis
- infection through:
1. direct implantation (open wound)
2. bloodborne spread (lung TB to bone)
3. weakened immunity or vascular insufficiency
4. extension from contiguous site
likely location of osteomyelitis with age?
children: long bone (upper and lower limbs)
adult: feet, vertebral spine, femur
what is the progression of osteomyelitis?
- Bacterial infects and proliferates producing bone microabscesses
- Infection and inflammation spread within shaft of bone, Haversian system and periosteum
- If infection extends to joint or synovium -> septic arthritis
- Inflammation impairs blood supply to bone causing bone ischaemia and necrosis
- Inflammatory exudate lifts periosteum away from the bone cortex
- Rupture of the periosteum leads to an abscess in the surrounding soft tissue and the eventual formation of a draining sinus in chronic osteomyelitis
- The lifting of the periosteum by inflammatory exudate forms a layer of woven bone called involucrum
- The involucrum often surrounds the underlying dead infected bone
What is chronic osteomyelitis?
- acute osteomyelitis may persist and progress to chronic osteomyelitis
- due to weakened immunity
- potential complications of chronic OM:
pathological fracture and deformity
secondary amyloidosis
sepsis or distant sites of infection
malignant transformation
What is tuberculous osteomyelitis?
- type of chronic osteomyelitis caused by mycobacterium
- spread to bone from lung via blood borne route or lymphatic drainage
KEY histological features:
- chronic inflammation with epithelioid granulomas and necrosis
What is spinal tuberculous osteomyelitis?
- affects vertebral spine
- can cause:
compression fractures
severe deformities
neurological deficits due to cord and nerve compression
What is spondylodiscitis?
- infection of intervertebral disc and adjacent vertebrae
