Repeated fractures in children

Introduction Repeated fractures in children are characterized by osteogenesis imperfecta. Traverse fractures and spiral fractures are the most common. About 15% of fractures occur at the metaphysis. It is mainly characterized by collagen dysplasia, which is the main component of the whole body skin, tendons, bones, cartilage and other connective tissues. In terms of bones, osteoblast production is reduced or viability is reduced, alkaline phosphatase is not produced, or both are combined. As a result, subperiosteal osteogenesis and endochondral ossification are impeded, and bone formation is not normal.

Cause

The cause of this disease is unknown, and it is a congenital developmental disorder. Male and female are equal. Can be divided into congenital and delayed hair. Congenital type refers to the onset in the uterus, and can be divided into fetal and infant types. The condition is severe, mostly death, or death shortly after delivery. It is an autosomal recessive inheritance. The delayed type is milder and can be divided into a child type and an adult type. Most patients can survive for long periods of time and are autosomal dominant. More than 15% of patients have a family history.

The disease is an autosomal dominant or recessive inheritance, which may be a sporadic case. The transmission of the blue sclera is 100%, and hearing loss varies with age. Sporadic cases are often caused by new mutations, often associated with the age of parents.

The occurrence of osteogenesis imperfecta is mainly due to mutations in the genes encoding the 1 or 2 procollagen (Pro-1 or Pro-2) chain of type I collagen (ie COL1A1 and COL1A2), resulting in type I collagen synthesis disorders, connective tissue The amount of collagen, especially the type I collagen, is reduced. Collagen is the main collagen component of tissues such as bones, skin, sclera and dentin, and the disease changes in these areas.

(two) pathogenesis

It is mainly characterized by collagen dysplasia, which is the main component of the whole body skin, tendons, bones, cartilage and other connective tissues. Some authors have reported that there are too many proline components in the patient's collagen tissue. When the patient takes oral proline, the peak of blood proline is lower than that of normal children.

In terms of bones, osteoblast production is reduced or viability is reduced, alkaline phosphatase is not produced, or both are combined. As a result, subperiosteal osteogenesis and endochondral ossification are impeded, and bone formation is not normal. The change in histology is that the trabecular bone in the cancellous and cortical bones becomes fine and calcified, with clusters of chondrocytes, cartilage-like tissue and calcified bone-like tissue. The calcium deposits of the bones proceeded normally. The above pathological changes cause bone fragility and bone softening.

an examination

Related inspection

X-ray examination of bone and joint MRI in mammography

The auxiliary examination methods for this disease are mainly X-ray examination and laboratory examination:

1, X-ray inspection:

X-rays are mainly characterized by bone deficiency and generalized bone sparseness.

(1) The long bones are slender, the trabecular bones are sparse, semi-translucent, and the cortex is as thin as a pencil. The medullary cavity is relatively large, and cystic changes may occur in severe cases. Both ends of the bone are swollen and sinuous, and there are many old or fresh fractures. Some have been deformed and the backbone is bent. Some malformations are caused by muscle traction, such as hip varus, arch of the femur and tibia. Some patients will form a rich spheroidal callus after the fracture. The number and scope of the patient will be misdiagnosed as osteosarcoma. In other patients, the cortical bone is thicker and is called "thick bone type." Rare.

(2) Delayed calcification of the skull, thinning of the bone plate, bulging of the double tibia, wide front anterior, relatively dense rock bone, and flat skull base. Calcium calcification is not good, and permanent tooth development is acceptable.

(3) The vertebral body is thin, double concave, and the trabecular bone is sparse, and the intervertebral disc is double convexly compensatory. There may be scoliosis or kyphosis.

(4) The ribs are bent downward from the rib corners, and multiple fractures are often seen. The pelvis is triangular and the pelvis becomes smaller.

(5) Joints: There are mainly four changes:

One part of the patient may cause depression of the acetabulum and femoral head into the pelvis due to osteomalacia.

2 Intramembranous osteogenesis of the backbone can cause the bone to become thinner, but the bone end of the joint is relatively coarse due to the normalization of the cartilage calcification and the cartilage osteogenesis.

Most of the patients had more calcifications in the epiphysis. It may be due to the unabsorbed calcium in the cartilage during cartilage osteogenesis.

4 pseudo-articular joint formation, due to multiple fractures, the formation of cartilage defects at the fracture, X-ray film looks like a pseudo-articular formation.

(6) Skeleton: The bone damage of early and late-onset osteogenesis is different. Early-onset patients showed multiple fractures of the long bones with osteophyte formation and skeletal deformation; late-onset patients had obvious osteoporosis, multiple fractures, long bone bending or short femur and thick "accordion"-like changes. The bone is too thin or the backbone is too thick, and the bone changes in a sac or honeycomb shape. The long cortical bone defect is rough. The ribs are thinner, the lower edge is irregular or the thickness is different, and the fingers are changed like peanuts. The alveolar plate absorbs. Scoliosis, vertebral body flattening, or increased vertebral body upper and lower diameter, can also be expressed as small vertebral body, pedicle growth. The skull is thin, the seam is present, the front and rear are convex, and the occiput is drooping. The metaphyseal ends of the long bones of the extremities have a majority of transverse dense lines, and the density of the periorbital cartilage discs is increased and uneven. MRI and CT examinations revealed proliferative osteophyte formation in the lesions of osteogenesis imperfecta, sometimes resembling bone tumors.

2. Ultrasound examination

Ultrasound examination of the fetal skeletal system can detect congenital bone development disorders early. The experience of Garjian et al. shows that three-dimensional ultrasound can obtain stereoscopic anatomical positioning, so it is superior to two-dimensional ultrasound examination, and the former is more likely to find deformities of the head, face and ribs.

3. Laboratory inspection:

Generally normal, sometimes there may be an increase in blood phosphatase, which may be due to increased osteoblast activity after traumatic fracture. Very severe cases have a reduction in plasma calcium and phosphorus, but are rare.

Patients with blood calcium, phosphorus and ALP are generally normal, a small number of patients with ALP can also be increased, urinary hydroxyproline increased, and some with amino acid urine and mucopolysaccharide urine. Two-thirds of patients had elevated serum T4. Due to the increase in thyroxine, there is a platelet aggregation disorder in leukocyte oxidative metabolism.

Differential diagnosis

First, some scholars believe that the key point in the diagnosis of this disease lies in the identification of achondroplasia.

Cartilage hypoplasia is a systemic symmetrical cartilage development disorder, mainly manifested as pygmy deformities with short limbs but almost normal trunk. Characteristics of severe cartilage hypoplasia: the fetal head is enlarged, the double top diameter is widened; the rib is thick and short, the thorax is narrow, but the lower thoracic cavity is relatively enlarged; the fetal abdomen is bulging and the abdominal circumference is enlarged; the fetal limbs are short and the long bone is short and long. More accompanied by bending, bone end enlargement; increased amniotic fluid volume. The limbs of these two malformed fetuses are short, but the osteogenesis is incomplete, the bone density is reduced, the cortex is thin, the fracture is very easy, and the bone deformity and thoracic deformation are caused by the fracture, and the chondroma hypoplasia is generally not associated with the fracture.

Second, it should also be noted that this disease can cause skeletal malformation, fracture and osteophyte formation, so the X-ray diagnosis should be differentiated from osteosarcoma, rickets, abnormal bone fiber and congenital pseudoarthrosis.

1. Delayed juvenile osteoporosis

General osteoporosis, vertebral biconcave deformation or flat vertebral body, as well as lateral kyphosis and easy fracture of the spine are similar to osteogenesis imperfecta. However, the latter still has a large head, bilateral humerus external protrusion, flat skull base, small triangular face, blue sclera, multiple suture bones, and family history are different from the former.

The diagnosis of type I OI is sometimes very difficult. I should think of type I OI in the case of osteoporosis in adolescents or severe osteoporosis in perimenopause.

2. Bone softening and rickets without bone fragile and easy to fold, no blue sclera. The front of the mineralization is blurred with a brush or cup, and the cartilage disc is widened. Bone softening is more common in pregnant women or lactating women, with bone pain, serum calcium and phosphorus are reduced.

3. Vitamin C deficiency

The patient also has osteoporosis, but there may be bleeding points in the subcutaneous, intermuscular, and epithelial membranes. There may be severe pain and pseudospasm, and calcification may occur after the fracture is healed.

4. Osteosarcoma

A large number of osteophytes can occur in the fractured part of patients with osteogenesis imperfecta. Most are benign. Only a few have erythrocyte sedimentation rate and elevated blood ALP, and bone biopsy can be identified if necessary.

5. Hyperactivity syndrome

Joint relaxation and hyperactivity are one of the characteristics of OI and should be associated with other collagen-deficient diseases that cause this change, such as benign joint hyperactivity syndrome, Morquio syndrome, Ehlers-Danlos syndrome, Marfan syndrome, Larsen syndrome. Identification. In addition, a special type of OI can be expressed as Cole-Carpenter syndrome, or adolescent osteoporosis, Ehlers-Danlos syndrome, OI with primary hyperparathyroidism, OI with dentinogenesis imperfecta (DI), OI-like syndrome should be noted for identification.

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