Congenital Disorders of the MSK System

Question 1

Brittle bone disease is known by which other name?

Answer 1

Osteogenesis imperfecta

Question 2

What causes osteogenesis imperfecta?

Answer 2

A defect in the maturation and organisation of type 1 collagen in bone

Question 3

The majority of osteogenesis imperfecta are autosomal ___________

Answer 3

Dominant

Question 4

How does osteogenesis imperfecta present?

Answer 4

• Multiple fragility fractures
• Short stature
• Multiple deformities
• Blue sclerae
• Loss of hearing

Question 5

Rarer cases of osteogenesis imperfecta are autosomal __________ and are either ________ in the perinatal period or associated with __________ __________

Answer 5

Rarer cases of osteogenesis imperfecta are autosomal recessive and are either fatal in the perinatal period or associated with spinal deformity

Question 6

As well as osteogenesis imperfecta, osteopenia can occur in which other key circumstance?

Answer 6

Prematurity

Question 7

How do bones appear in osteogenesis imperfecta?

Answer 7

1. Thin and gracile
2. Thin cortices
3. Osteopenic

Question 8

How do fractures heal in osteogenesis imperfecta?

Answer 8

Poorly with abundant but poor quality callus

Question 9

How are fractures treated in osteogenesis imperfecta?

Answer 9

Splintage, traction or surgical stabilisation

Question 10

Some cases of progressive osteogenesis imperfecta may require which types of treatment?

Answer 10

Osteotomies

or

Intramedullary stabilisation for correction via the Sofield procedure

Question 11

What are connective tissue disorders?

Answer 11

Genetic disorders of mainly type 1 collagen synthesis affecting bone, tendon and ligaments

Question 12

How do connective tissue disorders affect joints?

Answer 12

They can cause hypermobility

Question 13

How is osteogenesis imperfecta different from other connective tissue disorders such as Marfan’s syndrome?

Answer 13

It predominantly affects the type 1 collagen of bone rather than the soft tissues

Question 14

How is generalised joint laxity inherited?

Answer 14

In a dominant manner

Question 15

What are the two main downsides to generalised joint laxity?

Answer 15

1. More prone to soft tissue injuries (sprains etc)
2. Recurrent dilocations of joint (shoulder etc)

Question 16

What is Marfan’s syndrome?

Answer 16

A condition caused by autosomal dominant (or sporadic mutation) of the fibrillin gene causing tall stature with disproportionately long limbs and ligamentous laxity.

Question 17

What are the main associated features of Marfan’s syndrome?

Answer 17

• High arched palate
• Scoliosis
• Pectus excavatum
• Eye problems (lens dislocation, retinal detachment, glaucoma)
• Aortic aneurysm and regurgitation
• Cardiac valve incompetence (mitral valve prolapse and regurgitation)
• Spontaneous pneumothorax
• Abical blebs
• Arachnodactyly
• Long limbs

Question 18

Arachnodactyly is a feature of Marfan’s syndrome, but what does it describe?

Answer 18

Long fingers

Question 19

What is the main cause of premature death in Marfan’s syndrome?

Answer 19

Cardiac abnormalities

Question 20

What is the medial term for short stature?

Answer 20

Skeletal dysplasia

(dwarfism is a redundant term)

Question 21

What causes short stature?

Answer 21

Genetic error (either inheritied or sporadic mutation) which impacts bone and connective tissue development

Question 22

Short stature can be either __________ or _______________

Answer 22

Short stature can be either proportionate or disproportionate

Question 23

What is the most common type of short stature?

Answer 23

Achondroplasia

(AD or sporadic mutation)

Question 24

How does achondroplasia present?

Answer 24

• Prominent forehead
• Disproportionately short limbs
• Widened nose
• Joint laxity
• Normal mental development

Question 25

What is the relevant orthopaedic treatment for achondroplasia or a skeletal dysplasia?

Answer 25

* Deformity correction (e.g. scoliosis) * Limb lengthening * Potentially growth hormone therapy

Question 26

How are muscular dystophies generally aquired?

Answer 26

X-linked recessive inheritance | (hence, they are rare)

Question 27

Muscular dystophies result in what over time?

Answer 27

Progressive muscle weakness and wasting

Question 28

Duchenne muscular dystophy is caused by what?

Answer 28

A defect in the dystophin gene responsible for calcium transport (hence, muscle weakness is implicated)

Question 29

What is Gower's sign?

Answer 29

A sign of muscle weakness in young boys with Duchenne muscular dystrophy The boy will get onto all fours, then progress to putting their hands on their knees before standing up which highlights the struggle

Question 30

Why do patients with Duchenne muscular dystrophy die early?

Answer 30

By around age 20 they suffer from respiratory failure and progressive cardiac failure

Question 31

How is Duchenne muscular dystrophy diagnosed?

Answer 31

1. Raised serum CK 2. Abnormalities on biopsy

Question 32

How can Duchenne muscular dystrophy be treated?

Answer 32

* Physiotherapy * Splitange * Deformity correction * Spinal surgery (for severe scoliosis) These are all supportive options, there is no cure

Question 33

What is Becker's muscular dystrophy?

Answer 33

Essentially a milder version of Duchenne muscular dystrophy Boys can walk into their teens and survive into their 30s or 40s

Question 34

What is Ehlers-Danlos syndrome?

Answer 34

A heterogenous condition which is often AD inherited It results in abnormal elastin and collagen formation

Question 35

How does Ehlers-Danlos syndrome present?

Answer 35

1. Joint hypermobility and instability 2. Vascular fragility (bruising is seen) 3. Scoliosis

Question 36

How can Ehlers-Danlos syndrome be treated?

Answer 36

Bony surgery - for dislocating joints

Question 37

Why is surgery an issue for patient's with Ehlers-Danlos syndrome?

Answer 37

Bleeding is an issue (vascular fragility) and healing is poor

Question 38

Down syndrome results in short stature, which other symptoms often co-exist with this?

Answer 38

1. Joint laxity 2. Recurrent dislocation (especially patella) 3. Atlanto-axial instability in the c-spine