Bones and Joints: Osteoarthritis, Osteoporosis, Calcium, VitD, Phosphate

Question 1

Osteoarthritis

• epidemiology
• pathophsyiology, risk factors
• presentation
• investigations, diagnosis

Answer 1

Increases with age

• equal in male and females
• obesity
• past injury

Wear and tear of joint

Joint pain worse with use
Unilateral
DIP (Heberdens), PIP(Bouchards), CMC hip, knee - crepitus
No systemic upset

Generally a clinical diagnosis
Xray can help 
-Loss of joint space
-Osteophytes
-Subchondral cysts
-Subchondral sclerosis

Conservative

• weight loss, regular exercise, heat and ice
• simple analgesia, NSAIDs, capsaicin => joint injections

Joint replacement if prolonged, severe

Question 2

Osteoporosis

• epidemiology
• pathophysiology, risk factors

Answer 2

Increased bone loss => low bone mass, reduced strength, increased fragility fracture risk

White, Asian
Post menopausal women
Past #/FHx of #
Underweight BMI
High alcohol, smoking, CS use
Low VitD, Ca
Inflammatory conditions
Bone mets, cancer

Question 3

Osteoporosis

• presentation
• investigations, diagnosis

Answer 3

Fragility fracture

• kyphosis, back pain - vertebral fracture
• low impact trauma

FRAX score - assess 10 year risk of fragility fracture

• low risk => reassure, lifestyle advice
• intermediate risk => DEXA needed for further info
• high risk => DEXA

Question 4

Criteria for assessing fragility fracture risk

Answer 4

Female 65+
Male 75+

Younger patients with

• past fragility fracture, falls, FHx of hip fracture
• current/frequent CS
• underweight BMI
• Smoking
• Alcohol intake above weekly recommendations

Question 5

Interpretation of DEXA scan results

Answer 5

T score - your measurement compared to the young reference population

T score

• -1+ = normal
• -1 - -2.5 = osteopenia
• U-2.5 = osteoporosis

Question 6

Osteoporosis

-low risk management

Answer 6

Regular exercise

• outdoors => VitD
• strength training

Balanced diet
Smoking cessation
REduce alcohol

NO DRUG MANAGEMENT

Question 7

Osteoporosis

-intermediate risk management

Answer 7

LOW RISK MANAGEMENT + DRUG MANAGEMENT if DEXA = U-2.5
If -2.5+ => low risk management

1st line - PO alendronate
-other options zolendronate, raloxifene, denosumab, teriparatide

Ca, VitD

• If only VitD low => prescribe VitD
• If Ca low => prescribe Ca + VitD

Question 8

Osteoporosis

-high risk management

Answer 8

LOW RISK + DRUG if DEXA = U-2.5
If -2.5+ => modify risk factors, treat underlying conditions and repeat DEXA

1st line - PO alendronate
-other options zolendronate, raloxifene, denosumab, teriparatide

Ca, VitD

• If only VitD low => prescribe VitD
• If Ca low => prescribe Ca + VitD

Question 9

Bisphosphonates

• MOA
• SE

Raloxifene
-MOA

Denosumab

• MOA
• SE

Teriparatide
-MOA

Answer 9

Bisphosphonate - Inhibit osteoclasts

• reflux => esophageal reaction
• MRONJ
• increased stress fracture risk

Raloxifene - SERM

Denosumab - inh RANKL => prevents osteoclast development
-infection, MRONJ, atypical fracture

Teriparatide - intermittent bone formation from anabolic action of PTH
-when stopped, use antiresorptive

Question 10

Bone profile blood test
-what is tested
Routine bone investigations and why

Answer 10

Bone profile blood test

• Ca, PO4
• Albumin
• ALP

FBC, CRP - signs of myeloma, lymphoma
U&E, LFTs - CKD, CLD
TFT, PTH - hyperthyroidism, PTH
VitD - deficiency
Urine cortisol/dexmeth suppression- Cushings 
Urine and serum - myeloma
Coeliac screen - malabsorption

Question 11

Most common bone metastases and locations

Answer 11

MOST COMMON - Prostate
Breast
Lung

MOST COMMON - Spine
Pelvis
Ribs
Skull
LEAST COMMON - Long bones

Question 12

Parathyroid hormone
-function

Active VitD
-function

Answer 12

PTH - increases serum Ca, decreases serum PO4

• Bone => Increase blood Ca
• Kidney => Increase Ca reabsorption from DCT, decreases PO4 reabsorption
• Intestine via kidney => VitD increases => increases GI Ca uptake

VitD - increases serum Ca AND PO4

• Bone => increase blood Ca
• Kidney => increase Ca and PO4 uptake
• GI => increase Ca uptake

Question 13

Hypocalcemia

• causes
• presentation
• management

Answer 13

Causes

• Low VitD, PTH, Mg
• CKD
• Acute pancreatitis

Neuromuscular irritability - tingling of peripheries and mouth, cramps
Fatigue, anxiety

Acute - IV Ca gluconate + ECG monitoring
Definitive - address underlying cause

Question 14

Osteomalacia

• presentation
• investigations and diagnosis
• management

Answer 14

Low Ca, PO4, VitD, high ALP => inadequate bone mineralization => soft bones

Diffuse joint, bone pain
Muscle weakness, difficulty walking
Easy fractures, bendy bones

VitD, Ca supplementation