Bone disease Flashcards
What is osteoporosis?
A skeletal disorder characterised by decreased bone mass leading to decreased bone strength and increased fracture risk
What is the BMD definition of osteoporosis and osteopenia?
Osteoporosis - T score less that - 2.5
Osteopenia - T score between 1 and 2.5
What test is used to diagnose osteoporosis?
DEXA scan (usually of the lumbar spine and hip)
What is the brief pathophysiology of osteoporosis?
Imbalance between the rate of bone resporption and formation (osteoclast and osteoblast activity)
How do bisphosphonates work?
Inhibit osteoclasts and so stop resporption of bone.
How does raloxifene work?
It is an oestrogen receptor modulator that can be used in post menopausal women.
How does denosumab work?
A humanized monoclonal antibody against RANK ligand that reduces the formation of osteoclasts. It improves BMD and reduces fracture in post menopausal women
How does strontium work?
This is a second line agent when bisphosphonates aren’t tolerated and works by remodelling the bone structure with anti resorptive and bone formation effects.
What is an example of a bisphosphonate?
Alendronic acid (oral) Zolendronic acid (IV infusion)
How and why is zolendronic acid given?
5mg infusion once yearly in osteoporosis
5mg dose once in pagets disease
What is the first line treatment for osteoporosis?
Oral bisphosphonates (alendronic acid/risedronate)
What does the fracture risk have to be in someone who has not had a fracture in order to get a bisphosphonate?
10% in 10 years
What is teriparatide?
A recombinant form of PTH. It is an effective bone growing treatment used in severe osteoporosis, Small bursts of PTH increase osteopblast activity and are helpful for improving bone density
What drug is used in people with severe spinal osteoporosis?
Teriparatide. This is a recombinant PTH which is used to grow bone
Describe the treatment pathway for someone with newly diagnosed osteoporosis?
- Oral bisphosphonates (also calcium and vitamin D)
If unable to tolerate/poor response - IV bisphosphonates or denosumab (monoclonal antibody)
- HRT, tibolone, ibandronic acid or raloxifene
- Strontium
Which patients should not get strontium?
Ischaemic heart disease
Periperal artery disease
Cerebrovascular disease
Uncontrolled hypertension
What is tibolone and how does it work in osteoporosis?
Has weak estrogenic, progestegenic and androgenic activity
What is pagets disease?
A disorder of bone remodelling whereby there is a large increase in bone resprption , mediated by large multinucleated osteoclasts. The osteoblasts respond by producing weak disorganised bone. Repeated cycles of this lead to areas of bone becoming abnormally large and deformed.
What are common sites for pagets to effects?
Pelvis Lumbar spine Femur Skull Tibia
What are some of the complications that can arise a result of pagets disease?
- Deafness (auditory nerve entrapment)
- Cranial nerve palsy
- Cardiac hypertrophy
- Spinal stenosis
- Secondary OA
- Fractures
- Osteosarcoma
- Tibial bowing
How do you investigate pagets disease and what results will you see?
Blood: High alkaline phosphatase levels (correlate with the extent of skeletal involvement)
X Ray: Disorganised patterns of bone with areas of lysis and sclerosis
Isotope bone scan: Areas of focal increased uptake
What is the treatment for pagets disease?
Bisphosphonates
Surgery if fracture or tumour
What is rickets?
Failure of bone mineralisation in the growing skeleton of children. This causes poor mineralisation of cartilage in the epiphyseal growth plates of children. It is causes by vitamin D deficiency
What is osteomalacia?
The softening of bones caused by impaired metabolism due to inadequate levels of phosphate, calcium and vitamin D
How does rickets present?
Bone pain Skeletal deformity Muscle wekness Fracture Rarely tetany or convulsion due to hypocalcaemia
How does osteomalacia present?
Bone pain
Muscle weakness
Fracture
Hypocalcaemia (chovsteks sign - abnormal reaction to facial nerve stimulation)
What do they laboratory results show in osteomalacia/rickets?
Low phosphate Low calcium Raised Alk Phos Low Vitamin D Raised PTH Low urinary calcium
What radiological changes are seen in rickets?
Delayed opacification of the epiphyses
Widened growth plates
Thin cotices
What radiological changes are seen in osteomalacia?
Loosers zones - spontaneous incomplete fractures
