Causes and diagnosis of recurrent fractures in children

In life, I find that some children break bones after falling. They are very fragile. I believe that you often see children suffering from recurrent fractures around you. How much do you know about this phenomenon? Do you also want to know how it was triggered? Below I will introduce some knowledge about recurrent fractures in children. I hope it will be helpful to you and help you protect your children’s health.

1. Causes

The cause of this disease is unknown and it is a congenital developmental disorder. Males and females are equally affected. It can be divided into congenital type and delayed type. The congenital type refers to the onset of the disease in the uterus, which can be further divided into fetal type and infantile type. The condition is serious, and most cases result in death, or death within a short period after delivery. It is an autosomal recessive inheritance. The late-onset patients have milder symptoms and can be divided into childhood type and adult type. Most patients can survive long term and the disease is inherited in an autosomal dominant manner. More than 15% of patients have a family history.

The disease is inherited in an autosomal dominant or recessive manner and may be a sporadic case. The blue sclera has a 100% transmission and hearing loss varies with age. Sporadic cases are mostly caused by new mutations and are often related to the advanced age of the parents.

The occurrence of osteogenesis imperfecta is mainly due to mutations in the genes (i.e., COL1A1 and COL1A2) that constitute the α 1 or α 2 procollagen (Pro-α 1 or Pro-α 2) chains of type I collagen, which leads to type I collagen synthesis disorders and a decrease in the amount of collagen in connective tissue, especially type I collagen. Collagen is the main collagen component of tissues such as bones, skin, sclera and dentin, so the lesions in these areas are more obvious.

2. Pathogenesis

It is mainly manifested in the maldevelopment of collagen, the main component of the skin, tendons, bones, cartilage and other connective tissues throughout the body. Some authors reported that the patient's collagen tissue contained too much proline. When the patient took proline orally, the peak level of proline in the blood was lower than that of normal children.

In bones, the main symptoms are decreased osteoblast production or decreased activity, inability to produce alkaline phosphatase, or both. As a result, subperiosteal ossification and endochondral ossification are hindered and normal bone formation cannot occur. The histological changes are that the trabeculae in the cancellous bone and cortical bone become small and incompletely calcified, and groups of chondrocytes, cartilage-like tissue and incompletely calcified bone-like tissue can be seen in between. Calcium deposition in bones proceeds normally. The above pathological changes cause bone brittleness and osteomalacia.

1. Diagnosis

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

X-ray examination:

X-rays mainly show bone deficiency and general osteoporosis.

① In long bones, they appear slender, with sparse trabeculae that are translucent, and the cortex is as thin as a pencil drawing. The medullary cavity becomes relatively larger and may become cystic in severe cases. The two ends of the bone are enlarged and clubbed, and multiple old or fresh fractures can be seen. Some have abnormal connections and bent backbones. Some deformities are caused by traction on muscle attachments, such as hip vara and bowing of the femur and tibia. Some patients will develop abundant spherical callus after a fracture, the large number and wide range of which may lead to misdiagnosis of it as osteosarcoma. Some other patients have thicker cortical bone, which is called "thick bone type". Rare.

② Skull calcification is delayed, the bone plates become thinner, the bilateral temporal bones are bulging, the anterior fontanelle is wide, the petrous bones are relatively dense, and the skull base is flat. The deciduous teeth are poorly calcified, but the permanent teeth are developing well.

③ The vertebral body becomes thinner and biconcave, the trabeculae are sparse, and the intervertebral disc is compensatory and enlarged in a biconvex shape. There may be scoliosis or kyphosis.

④ The ribs bend downward from the costal angle, and multiple fractures are often seen. The pelvis becomes triangular and the pelvic cavity becomes smaller.

2. Joints: There are mainly four types of changes: ① In some patients, osteomalacia may cause the acetabulum and femoral head to sink into the pelvis; ② The intramembranous ossification of the bone shaft is impaired, which may cause the bone shaft to become thinner, but the cartilage calcification and endochondral ossification are still normal, so the bone ends that make up the joint are relatively thick; ③ Some patients have many calcification points in the epiphysis. This may be due to the failure to absorb calcium in the cartilage during endochondral ossification; ④ Pseudarthrosis. Due to multiple fractures, soft bone callus forms at the fracture site, which looks very much like pseudoarthrosis on X-ray films.

3. Bones: The manifestations of bone damage in early-onset and late-onset osteogenesis imperfecta are different. Early-onset patients often present with multiple fractures of long bones throughout the body, accompanied by callus formation and bone deformation; late-onset patients have obvious osteoporosis, multiple fractures, long bone bending or short and thick femurs with "accordion" changes. The shaft is too thin or too thick, and the bone becomes cystic or honeycomb-like. The long bone cortex is defective and rough. The ribs become thinner, the lower edge becomes irregular or curved with varying thickness, and the fingers become peanut-shaped. Alveolar plate resorption. Scoliosis, flattening of the vertebral body, or increase in the upper and lower diameters of the vertebral body, may also be manifested as growth of the vertebral bodies and pedicles. The skull is thin, with sutures present, bulging front and back, and a drooping occipital part. There are many transverse dense lines in the epiphyseal ends of the long bones of the limbs, and the density near the epiphyseal cartilage disc at the epiphyseal end increases and is uneven. MRI and CT examinations can reveal the formation of proliferative callus at the site of osteogenesis imperfecta lesions, which sometimes resemble bone tumors.

4. Ultrasound examination

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

5. Laboratory examination:

Generally, they are normal. Sometimes, there may be an increase in blood alkaline phosphatase, which may be due to the increased activity of osteoblasts after traumatic fracture. In extremely severe cases, there may be a decrease in plasma calcium and phosphorus, but this is extremely rare.

The patients' blood calcium, phosphorus and ALP are generally normal. ALP may be elevated in a few patients, and urinary hydroxyproline is elevated, and some are accompanied by aminoaciduria and mucopolysacchariduria. Serum T4 was elevated in 2/3 of the patients. Due to increased thyroid hormone, white blood cell oxidative metabolism is hyperactive and there is platelet aggregation disorder.

(III) It should also be noted that since this disease can cause bone deformity, fractures and callus formation, it should be differentiated from osteosarcoma, rickets, dysplasia of bone fibers and congenital pseudarthrosis in X-ray diagnosis.

1. Late-onset juvenile osteoporosis is characterized by generalized osteoporosis, biconcave vertebral deformation or flat vertebral bodies, kyphosis and easy fracture of the spine, which are similar to osteogenesis imperfecta; but the latter also has a large head, bilateral temporal bone protrusions, a flat skull base, a small triangular face, blue sclera, multiple suture bones, and a family history, which are different from the former.

The diagnosis of type I OI is sometimes very difficult. Whenever osteoporosis occurs in adolescents or severe osteoporosis occurs during perimenopause, the possibility of type I OI should be considered.

2. Osteomalacia and rickets without brittle bones and blue sclera. The mineralization front zone is fuzzy and brush-shaped or cup-shaped, and the epiphyseal cartilage disc is widened. Osteomalacia is more common in pregnant or lactating women, with bone pain and decreased serum calcium and phosphorus.

3. Patients with vitamin C deficiency also have osteoporosis, but there may be bleeding spots under the skin, between the muscles, and periosteum, severe pain and pseudoparalysis, and calcification may occur after fracture healing.

4. A large amount of callus may appear in the fractured part of patients with osteosarcoma and osteogenesis imperfecta. Most are benign. Only a few have elevated erythrocyte sedimentation rate and blood ALP, and bone biopsy can be performed for differentiation if necessary.

5. Joint hypermobility syndrome Joint laxity and hypermobility are one of the characteristics of OI, which should be differentiated from other collagen deficiency diseases that cause this change, such as benign joint hypermobility syndrome, Morquio syndrome, Ehlers-Danlos syndrome, Marfan syndrome, Larsen syndrome, etc. In addition, special types of OI may manifest as Cole-Carpenter syndrome, juvenile osteoporosis, Ehlers-Danlos syndrome, OI combined with primary hyperparathyroidism, OI combined with dentinogenesis imperfecta (DI), and OI-like syndrome, and they should be carefully differentiated.

The above is a detailed introduction to recurrent fractures in children. From it we can see the causes and some symptoms of fractures in children. I hope it will be helpful to you. Children's health is very important. They need to have a good physique from an early age to prevent their frequent fractures from causing the impact of other diseases. This requires us to strengthen our understanding of this aspect, increase our attention to it, protect the health of babies, and let them say goodbye to repeated fractures forever!