Congenital Disorders of the MSK System Flashcards
Brittle bone disease is known by which other name?
Osteogenesis imperfecta
What causes osteogenesis imperfecta?
A defect in the maturation and organisation of type 1 collagen in bone
The majority of osteogenesis imperfecta are autosomal ___________
Dominant
How does osteogenesis imperfecta present?
- Multiple fragility fractures
- Short stature
- Multiple deformities
- Blue sclerae
- Loss of hearing
Rarer cases of osteogenesis imperfecta are autosomal __________ and are either ________ in the perinatal period or associated with __________ __________
Rarer cases of osteogenesis imperfecta are autosomal recessive and are either fatal in the perinatal period or associated with spinal deformity
As well as osteogenesis imperfecta, osteopenia can occur in which other key circumstance?
Prematurity
How do bones appear in osteogenesis imperfecta?
- Thin and gracile
- Thin cortices
- Osteopenic
How do fractures heal in osteogenesis imperfecta?
Poorly with abundant but poor quality callus
How are fractures treated in osteogenesis imperfecta?
Splintage, traction or surgical stabilisation
Some cases of progressive osteogenesis imperfecta may require which types of treatment?
Osteotomies
or
Intramedullary stabilisation for correction via the Sofield procedure
What are connective tissue disorders?
Genetic disorders of mainly type 1 collagen synthesis affecting bone, tendon and ligaments
How do connective tissue disorders affect joints?
They can cause hypermobility
How is osteogenesis imperfecta different from other connective tissue disorders such as Marfan’s syndrome?
It predominantly affects the type 1 collagen of bone rather than the soft tissues
How is generalised joint laxity inherited?
In a dominant manner
What are the two main downsides to generalised joint laxity?
- More prone to soft tissue injuries (sprains etc)
- Recurrent dilocations of joint (shoulder etc)
What is Marfan’s syndrome?
A condition caused by autosomal dominant (or sporadic mutation) of the fibrillin gene causing tall stature with disproportionately long limbs and ligamentous laxity.
What are the main associated features of Marfan’s syndrome?
- 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
Arachnodactyly is a feature of Marfan’s syndrome, but what does it describe?
Long fingers
What is the main cause of premature death in Marfan’s syndrome?
Cardiac abnormalities
What is the medial term for short stature?
Skeletal dysplasia
(dwarfism is a redundant term)
What causes short stature?
Genetic error (either inheritied or sporadic mutation) which impacts bone and connective tissue development
Short stature can be either __________ or _______________
Short stature can be either proportionate or disproportionate
What is the most common type of short stature?
Achondroplasia
(AD or sporadic mutation)
How does achondroplasia present?
- Prominent forehead
- Disproportionately short limbs
- Widened nose
- Joint laxity
- Normal mental development
What is the relevant orthopaedic treatment for achondroplasia or a skeletal dysplasia?
- Deformity correction (e.g. scoliosis)
- Limb lengthening
- Potentially growth hormone therapy
How are muscular dystophies generally aquired?
X-linked recessive inheritance
(hence, they are rare)
Muscular dystophies result in what over time?
Progressive muscle weakness and wasting
Duchenne muscular dystophy is caused by what?
A defect in the dystophin gene responsible for calcium transport
(hence, muscle weakness is implicated)
What is Gower’s sign?
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
Why do patients with Duchenne muscular dystrophy die early?
By around age 20 they suffer from respiratory failure and progressive cardiac failure
How is Duchenne muscular dystrophy diagnosed?
- Raised serum CK
- Abnormalities on biopsy
How can Duchenne muscular dystrophy be treated?
- Physiotherapy
- Splitange
- Deformity correction
- Spinal surgery (for severe scoliosis)
These are all supportive options, there is no cure
What is Becker’s muscular dystrophy?
Essentially a milder version of Duchenne muscular dystrophy
Boys can walk into their teens and survive into their 30s or 40s
What is Ehlers-Danlos syndrome?
A heterogenous condition which is often AD inherited
It results in abnormal elastin and collagen formation
How does Ehlers-Danlos syndrome present?
- Joint hypermobility and instability
- Vascular fragility (bruising is seen)
- Scoliosis
How can Ehlers-Danlos syndrome be treated?
Bony surgery - for dislocating joints
Why is surgery an issue for patient’s with Ehlers-Danlos syndrome?
Bleeding is an issue (vascular fragility) and healing is poor
Down syndrome results in short stature, which other symptoms often co-exist with this?
- Joint laxity
- Recurrent dislocation (especially patella)
- Atlanto-axial instability in the c-spine
