MULTIPLE EPIPHYSEAL DYSPLASIA
DEFINITION:
A disorder of bones characterized by multiple abnormal epiphyses
resulting in stiff and painful joints and waddling gait.
EPIDEMIOLOGY:
- incidence: ?
- age of onset:
- childhood (2-10 years of age)
- risk factors:
- familial
- usually autosomal dominant with variable expression
- appears to be genetically heterogeneous:
- chrom.#: 1p32
- gene: COL9A2 which encodes the alpha-2 chain of type
IX collagen
- chrom.#: 19p13.1
- gene: cartilage oligomeric matric protein (COMP)
- M = F
PATHOGENESIS:
- first described by H.A.T. Fairbank in 1935 in a report to
the Royal Society of Medicine
- in 1937, S. Ribbing described a "hereditary multiple
epiphyseal disorder"
- in 1947, called "Dysplasia Epiphysialis Multiplex" by
Fairbank
- Multiple Epiphyseal Dysplasia (MED) appears to be
genetically heterogeneous with 2 basic variants:
- as many patients lie in a continuum between these two
variants it may be difficult to identify the form of disease in
a patient
- MED is characterized by abnormal ossification and thought to
be one of the more common osteochondrodysplasias
2. Genetic Defect
- genetic mutations -> delayed and irregular mineralization of
the epiphyseal ossification centres of various long bones ->
altered endochondral ossification within the affected epiphysis
-> phenotypic expression usually involving the hips, knees,
shoulders, ankles, hands, and feet
CLINICAL FEATURES:
- slowly progressive pain and stiffness of affected joints
- begins between 2-10 years of age
- usually affects the joints of the lower limbs (hips,
knees, and ankles) but upper limb joints may also be affected
(shoulders, elbows, wrists)
2. Others
- waddling gait and/or limp
- short hands and feet
- back pain
3. Complications
- osteoarthritis with advancing age - especially of knees
and hips
- avascular necrosis of the hips - usually unilateral
- osteochrondritis dissecans of the knee or hips
- dislocated patellae
- coxa vara, genu varum, genu valgum
- slight-to-moderate short stature (adult stature: 145-170
cm) due to lower limb shortening
INVESTIGATIONS:
- the radiologic finding of multiple abnormal epiphyseal
ossification centres is diagnostic
- affected epiphyses are:
- late ossifying
- small, irregular, mottled and/or fragmented
- irregularly mineralized
- usually found in the long bones of the lower limbs
- the involved epiphyses in the Fairbank Variant may be
small while those in the Ribbing Variant may be flat
- a single deformed mature epiphyseal centre may arise from
multiple late-appearing smaller coalescing centres
- involvement of epiphyses is usually symmetrical but not
necessarily uniform
- upper extremity involvement:
- may be minimal or severe
- affects the proximal humerus (shoulder), elbow, and
wrist joints
- the distal ulna may be longer than the radius leading to
subluxation
- the carpal (and tarsal) bones may be affected with
delayed, small, and irregular ossification centres
- the tubular bones of the hands are often shortened with
the middle and distal phalanges most commonly affected
2. Bones
- short, broad femoral neck
- mild metaphyseal flaring
- short metacarpals and phalanges
- diminished length of tubular bones
- double-layed patellae
- flattening and deformation of the joint surfaces
eventually leads to articular deformation of the affected
joints and osteoarthritis
3. Thoracic Vertebrae
- usually spared but also:
- blunted, ovoid, or flattened
- mild end-plate deformities
- Schmorl nodes
- no kyphosis or scoliosis
MANAGEMENT:
- multidisciplinary approach:
- Paediatrics, Orthopedic Surgery, Physiotherapy
- genetic counseling
- pain control
- osteoarthritis management
2. Surgery
- osteotomy of the pelvis or the collum femoris
2. Genu Varum or Valgum
3. Prognosis
- normal life span
- osteoarthritis especially of the hip
ADDITIONAL REFERENCES:
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