Pediatric orthopedic cases 32

CASE                               32                               

 

You are called to the emergency room to evaluate an 11-month-old, nonambulatory girl with a femur fracture. On examination, she is in the bottom 5% for height and weight. She has a triangular face, white sclerae, normal dentition, and reacts to your words with turning of the head to follow you. There is an obvious deformity of the right femur with tenderness to palpation and deformity of the left tibia without any tenderness to palpation. There is no bruising or skin lesions. On skeletal survey she

has irregular intrasutral bones in addition to the normal cranial bones. There are multiple vertebral compression fractures, a right midshaft femur fracture, and deformity of the left tibia with evidence of healing.

What is causing these fractures?

1. Child abuse

2. Nutritional deficiency

3. Abnormal collagen type I

4. Normal

 

Discussion

The correct answer is (C). This case describes a classical presentation of osteogenesis imperfecta (OI). Osteogenesis imperfecta is a condition of abnormal collagen type I, either quantitative or qualitative. The most popular described mutation is a glycine substitution that decreases cross-linking and prevents the formation of the triple helix. Child abuse (A) should always be considered in a child who presents with multiple fractures, but other features (triangular face, wormian bones, vertebral compression fractures) suggest osteogenesis imperfecta. Long bone fracture in a nonambulatory child is never a normal presentation (D), and child abuse or bone disease should always be considered.

What type of OI is this?

1. I

2. II

3. III

4. V

5. VIII

 

Discussion

The correct answer is (A). Type I OI is mild and presents with blue sclerae, 50% have hearing deficits, may have dental involvement, and is autosomal dominant (A). Type II OI is lethal at birth with blue sclerae and is autosomal recessive (B). Type III OI is described in the above scenario with normal sclerae, triangular face, wormian bones, multiple fractures, vertebral compression fractures, or “codfish” vertebrae, can have basilar invagination, and is autosomal recessive (C). This is the most severe of the survivable types. Type V OI is autosomal recessive and presents with hypertrophic callus formation and ossification of the interosseus membranes

between the radius and ulna and tibia and fibula (D). Type VIII OI has white sclera, bulbous metaphyses, involves a mutation in the LEPRE 1 gene, is often lethal at birth, and is autosomal recessive (E).

This child has another tibia and femur fracture over the past year. What is treatment?

1. Vitamin D

2. Vitamin D and calcium

3. Vitamin C

4. Bisphosphonates

 

Discussion

The correct answer is (D). While vitamin D (A) and vitamin D with calcium (B) may improve the mineral availability to build stronger bones, they have not been shown to decrease fracture rates in children with osteogenesis imperfecta. Vitamin C (C) deficiency results in abnormal cross-linking of collagen, but this is not the underlying cause of OI and has not been demonstrated to change bone health in children with OI. Bisphosphonate treatment (D) is the correct answer and has been shown to decrease fracture frequency and increase cortical thickness in children with OI. Bisphosphonate therapy is recommended for children with OI who sustain two or more fractures within a year.

The radiographs at age 5 have multiple horizontal densities at the metaphyses, most notably at the distal femoral metaphyses.

What is the most likely cause?

1. A change in the child’s nutritional status

2. The child has had multiple significant illnesses

3. Multiple fractures at physis with growth arrest

4. Increased densities corresponding to bisphosphonates

5. This is a common finding due to OI collagen disruption

 

Discussion

The correct answer is (D). Nutritional status (A) and illnesses (B) can often cause changes in bone density with recovery described above and referred to as Harris growth lines (or growth arrest lines), these also are a key finding with cyclical bisphosphonate treatment in children with OI (D). A fracture at the physis can cause a growth line, growth arrest with shortening, or angular deformity (C), but is not

the most likely cause in this case with multiple horizontal densities). Growth arrest lines are common in OI due to bisphosphonate treatment, but are not common in untreated OI (E).

At age 6, despite bisphosphonate treatment she fractured her right femur again. What is the appropriate treatment?

1. Cast

2. Flexible nails

3. Expandable rod

4. Traction

 

Discussion

The correct answer is (C). While in children with normal bones cast treatment (A) or flexible nail (B) would be appropriate, children with osteogenesis imperfecta should be treated with an expandable rod (C). Traction may be used for older children in developing nations, but this is not the most appropriate treatment.

At age 11 the child develops scoliosis with a curve of 37 degrees. What is the treatment for her scoliosis?

1. Observe

2. Brace

3. Tethering

4. Fusion

 

Discussion

The correct answer is (D). In children with OI and scoliosis, bracing is ineffective

(B) and should be treated with a fusion (D). Fusion is recommended in curves greater than 45 degrees for mild types of OI and 35 degrees for severe OI, such as in this case. Fusion is often difficult and accompanied by halo traction and multiple rods due to the poor bone quality and high pullout rate. Tethering is not an indicated procedure for OI scoliosis (C). Observation is not recommended for curves in severe scoliosis greater than 35 degrees (A).

 

Objectives: Did you learn...?

 

 

Common findings in osteogenesis imperfecta? Fracture treatment for children with OI?

 

 

Radiographic findings in children with OI? Scoliosis treatment for children with OI?