Achondroplasia is the most common skeletal dysplasia characterized by short stature and distinctive craniofacial skeletal features due to a mutation in the FGFR3 gene. It is typically inherited in an autosomal dominant manner, with 90% of cases arising from spontaneous mutations, affecting approximately 10,000 individuals in the U.S. Diagnosis involves history taking, physical examination, laboratory tests, and radiographic findings, with management strategies focused on addressing clinical manifestations, including growth hormone therapy and monitoring for potential complications.

1. ACHONDROPLASIA

2. Introduction
 Structural abnormality in the bone leads to
disturbances in growth of the trunk or
extremities.
 More than 300 bone dysplasias have been
described, most of which are extremely rare
 Most of the bone dysplasias result in short
stature
 Some of the dysplasias are genetically
inherited, whereas others are not.

3. Anatomy of epiphysis

4. The Stages of Long Bone Development
 During ossification, osteoblasts transform into
osteoid, which progressively calcified, also by
osteoblast action. As the bone grows, the
osteoblasts become trapped in the matrix of
their own making and become osteocytes.
 In mature bone, a fine balance of osteoblast
and osteoclast activity maintains normal bone
structure

5. Definition
 “Achondroplasia” was first used by Parrot in 1878 to
describe a rhizomelic form of short-limbed dwarfism
associated with enlarged head, depressed nasal bridge,
short stubby trident hands, lordotic lumbar spine,
prominent buttocks, and protuberant abdomen.
 According to Salter Harris, Achondroplasia is the failure of
longitudinal growth in the cartilage of epiphyseal plate.
 Achondroplasia is inherited as an autosomal dominant trait
 Ninety percent of cases are the result of spontaneous
mutation

6. Epidemiology
 Worldwide, achondroplasia is the most common skeletal
dysplasia and dwarfism-form
 Incidence range between 1.3 per 100.000 live births and
1.5 per 10.000 live births
 Approximately 10,000 individuals are estimated to have
achondroplasia in the United States.
 About 80% of all "little people" have achondroplasia.
 The frequency is equal in males and females and all
races

7. Ossification
Enchondral Ossification
• Bone replace a cartilage template
• Osteoclast removes the cartilage, and
osteoblasts make the new matrix, which is then
mineralized
• Longitudinal bone growth
Netter’s Concise Orthopaedic Anatomy 2nd
Edition. 2010

8. Intramembranous Ossification
• Bone develops directly from mesenchymal
cell, then differentiate into osteoblast
• Flat Bone formation : Cranium, Pelvic, Clavicle
Ossification
Netter’s Concise Orthopaedic Anatomy 2nd
Edition. 2010

9. Ossification
Appositional
• Periosteal –mediated long bone growth (width)
• Osteoblasts make new matrix/bone on top of
existing bone.
Miller’s review of Orthopaedics Seventh Edition. 2016

10. The physis provides
longitudinal growth in
long bones.
In Proliferative zone,
chondrocytes divide and
stack into columns

11. In Achondroplasia, there is a mutation in the gene coding for Fibroblast Growth
Factor Receptor 3 (FGFR3)

12. Diagnosis
 Anamnesis
 Physical examination
 Laboratory examination
 Radiographic findings

13. Anamnesis
 Previous disease
 Family history
 History of development and growth
 Pregnancy history
 Uterine trauma
 Infection while pregnant
 Teratogenic events
 History during labour
 Nutritional status
 Previous trauma

14. Physical Examination
Penting untuk menentukan potensi tinggi genetik anak
dan dihitung dengan cara sebagai berikut:

15. Physical Examination
Craniofacial features
are as follows:
-Large calvarial bones in
contrast to the small
cranial base and facial
bones
-True megalencephaly
(large head) with frontal
bossing
-Midface hypoplasia

16. Physical Examination
Skeletal features are as follows:
 Disproportionate short stature: Male average adult
height 131 ± 5.6 cm; female average adult height
124 ± 5.9 cm; average adult height for both
approximately 4 feet

17. Thoracolumbar kyphosis
Genu Varum

18. Physical Examination
Neurologic
findings are as
follows:
-Hypotonia in
infancy and early
childhood
-Delayed motor
milestones

19. Laboratory Examination
 Direct DNA analysis of FGFR3 mutations is
used for prenatal screening in families at risk
(ie, parents who are heterozygous for either
the G1138A or the G1138C mutation).

20. Radiology Examination
 Fetal USG → Early diagnosis, skeletal anomalies
and measure long bones (fetal femoral length)
and evaluate the skull.

21. Plain X-Ray:
- Os cranium is relatively
enlarged compared to the face
accompanied by frontal
protrusion.
- Foramen magnum shrinks and
irregular funnel-shapped shape.
Plain X-Ray:
- Chest anteroposterior diameter
decreases with anterior rib
shortening.

22. -Bones of bone from the
hands and feet look short
and wide
-Trident-shaped hands are
often found
lumbar kifosis

23. - its length
decreases,
especially in the
proximal limb
segment
- The fibula
extends and
bends

24. Radiology Examination
Head CT Scan → neuroanatomic
abnormalities consistent with arrested
hydrocephalus, enlarged cranial ventricles,
changes in the corpus callosum are seen.
MRI → narrowing of the foramen
magnum and lumbar canal stenosis

25. MRI Brain
A large cranial vault with relatively short skull base with prominent forehead,
depressed nasal bridge Narrowing of the foramen magnum with cervicomedullary
kinking.

26. Differential Diagnosis
 Hypochondroplasia (skeletal displasia)
 Thanatophoric dysplasia
 SADDAN Syndrome → Severe Achondroplasia
with Development Delay and Acanthosis
Nigricans(skin pigmentation)
 Pseudoachondroplasia

27. Treatments and Managements
Based on clinical manifestations
 Short stature → GH therapy, extended limb
lengthening (complications are frequent)
 Kyphosis → bracing support to prevent
persistence of thoracolumbar kyphosis
 Hydrocephalus → know the symptomps of
increased ICP → ventriculoperitoneal shunting

30. Thoracolumbar Spinal Brace

31. Complications
Infants Toodlers and
Children
Adults
Neurologic • Intracranial hypertension
• Ventriculomegaly
• True hydrocephaly
• Sudden infant death
(rare)
Orthopedic • Kyphosis up to standing
position
• Knee hypermobility
• Hyperlordosis
• Genu vara
• External rotation
of the hips
• Lumbar spinal
stenosis
• Back pain
• Peripheral nerve
compression

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