Periosteal reaction

Introduction In the pathological condition, osteoblast activity in the periosteal inner layer is increased by the periosteal new bone produced. The periosteal reaction generally means that the bone is damaged or damaged. Histologically, osteoblasts in the periosteum can be seen to form new bone trabeculae. The periosteum is the structural structure of the bone, which is divided into the endosteal and the epithelium. The epicardium covers the surface of all bones outside the articular surface, consisting of the fibrous layer of the outer layer, the cell-forming layer of the inner layer, and the transition layer therebetween. The fibrous layer contains coarse collagen fiber bundles, and some fibers (sharpey fibers) penetrate the outer ring bone plate to fix the periosteum to the bone surface; the cell formation layer mainly contains bone cells, blood vessels, nerves and the like. The resting periosteum contains less cellular components, mainly mature fibrous tissue. When the periosteum is activated, each layer of cells can change into bone.

Cause

In the pathological condition, the osteoblast activity in the periosteal inner layer is increased by the periosteal new bone produced. The bone is damaged or damaged.

Many diseases can have a periosteal reaction, such as acute suppurative osteomyelitis.

an examination

Related inspection

CT examination of bones and joints of limbs and joints

Periosteal reaction

a. periosteal edema

Most studies have demonstrated that periosteal edema is an important sign for the diagnosis of occult fractures and early occult fractures. MRI T2WI and enhanced T1WI can clearly show periosteal edema, which is a linear high signal shadow next to the cortical bone. MRI dynamic enhancement scan of the lesion also obtained a time-signal intensity curve of the edematous periosteum, ie the periosteum began to strengthen gradually within 40 seconds of injection of the contrast agent, followed by an enhancement peak. Pathologically, the periosteal tissue structure of edema was loose, the gap of collagen fiber bundles increased, and the cell formation layer showed no significant change. Periosteal edema often coincides with bone marrow edema and surrounding soft tissue edema, and the mechanism may be congestive edema. In the animal model of bone tumor, periosteal edema occurred within 15 days after implantation of the tumor in the bone marrow cavity, and edema was also observed in the periosteum adjacent to the normal site during the late growth of the tumor, which was consistent with the clinical bone tumor case. Therefore, periosteal edema is considered to be an early periosteal reaction before the formation of new bone in the periosteum.

b. periosteal gingling, thickening

With the development of the lesions, pathological exudation, tumor tissue, etc. along the volkmann tube to the periosteum to pick up the periosteum, while stimulating periosteal hyperplasia, thickening. On MRI, the thickened periosteum was a linear image similar to the soft tissue signal on T1WI, and a higher signal line shape on T2WI (Fig. 2a), which was significantly enhanced, and the x-ray plain film could not show periosteal thickening. Histologically, the intraperiosteal and outer layer cells proliferated, and the number and shape of the cells in the cell formation layer were prominent. The outer fiber bundles also proliferated and thickened, and the thickened periosteum was observed to form bone-like tissue. The mechanism of periosteal thickening is that the fibrous layer of the outer layer of periosteum is transformed by the surrounding soft tissues such as fascia, fat and muscle. The fibroblasts of the fibrous layer are transformed into osteogenic cells through the enlargement of the nucleus and the increase of cytoplasm. It is further enlarged and accompanied by mitosis to form a cell-forming layer in which cells having a bone matrix secreting ability appear. Periosteal thickening occurs before the formation of new periosteal bone. During the process of continuous formation of periosteal bone, thickened periosteum is always seen covering the surface of the periosteal bone. Therefore, periosteal thickening is not only an early periosteal abnormality before the formation of new periosteal bone, but also necessary preparation for the continuous formation of periosteal new bone.

c. periosteal destruction

The destruction of periosteal bone is a common x-ray sign of malignant tumor. The tumor can destroy the periosteum after the destruction of the periosteal bone. The periosteal destruction on MRI is interrupted by the periosteal line shadow, and the damaged periosteum of the tumor invades the surrounding tissue. In the dynamic observation of the animal model of bone tumor, it was found that the bilayer structure of the periosteum was not simultaneously eroded by the tumor, but the cell layer of the periosteal inner layer was first replaced by the tumor cell, while the collagen fiber layer remained intact, in MRI. Shown above is the tumor pseudo envelope. The tumor continues to grow, the fibrous layer is destroyed, the periosteum is completely interrupted locally, and the tumor invades the surrounding fat and muscle from the broken periosteum. At this time, MRI can show the incompleteness of the periosteum. This result is consistent with the sign of the "pseudo-envelope" that separates the tumor from the normal tissue in the clinical bone tumor cases. The pathologically can also be considered as the unpermitted periosteal fibrous layer. . Some scholars in the staging of tumors, whether the tumor is destroyed by the cortical bone after invasion of the periosteum as one of the indicators of tumor growth staging, although the periosteum is still not clearly indicated the prognosis of the tumor, but the periosteum and periosteal bone will be the normal tissue Separation of tissues may have a preventive and slowing effect on tumor growth.

The periosteal changes observed by imaging scholars are not limited to the post-osteogenesis stage, but include periosteal edema, periosteal thickening, and periosteal destruction. These periosteal changes without calcification or calcification are traditional x-rays. The flat sheet cannot be displayed. If the "periosteal reaction" is still equated with "periosteal bone", the multiple periosteal changes shown by modern imaging cannot be fully described. Therefore, it is proposed that "periosteal new bone" represents the traditional "periosteal reaction", "periosteal reaction" represents periosteal edema, periosteal thickening and periosteal destruction that x-rays cannot show, and "periosteal abnormalities" including periosteal reaction and periosteal bone, Thereby achieving a comprehensive and accurate description of the purpose of periosteal changes.

Differential diagnosis

The periosteal reaction needs to be differentiated from the following symptoms.

Diffuse periosteal thickening: Perioid hyperplasia (pachydermoperiostosis) is divided into primary and secondary. The primary is autosomal dominant. Secondary is often triggered by liver, lung and digestive tract diseases or malignant tumors. This disease is more common in men.

Proliferative periostitis: The periosteum consists of dense connective tissue that coats the surface of the bone other than the articular surface and has many fiber bundles that protrude into the bone. In addition, the tendons and ligaments attached to the bone are woven together with the periosteum at the attachment site. Therefore, the periosteum is very strong in binding to bone. The periosteum is rich in blood vessels and nerves and is distributed in the bone and bone marrow through the nourishing pores of the bone. The medullary cavity and cancellous mesh are also lined with a thin connective tissue membrane called endosteum. The inner layer of the periosteum and the endosteal have the ability to differentiate into osteoblasts and osteoclasts to form new Bone and destruction, transformation of the generated bone, so it is of great significance for the occurrence, growth and repair of bone.

In childhood, osteoblasts in the periosteum can continuously produce new bone tissue, thicken the surface of the bone, make the bone thick, and heal after the fracture - bone regeneration, also depends on the osteoblasts of the periosteum. If the periosteal peeling is too much during surgery, the nutrition and regeneration of the bone will cause obstacles, affecting the healing of the fracture end and even causing bone necrosis. In the elderly, the periosteal thinning, the differentiation ability of osteoblasts and osteoclasts is weakened, and the repair function of the bone is reduced.

Periostitis: Periostitis is an infective periosteal injury caused by stress periosteal damage or purulent bacterial invasion caused by periosteal and periosteal vasodilatation, hyperemia, edema, or subperiosteal hemorrhage.

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