Unicameral bone cyst

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Unicameral bone cyst_table_infobox_0

Unicameral bone cystUnicameral bone cyst_header_cell_0_0_0
Other namesUnicameral bone cyst_header_cell_0_1_0 Solitary bone cystUnicameral bone cyst_cell_0_1_1

A unicameral bone cyst, also known as a simple bone cyst, is a cavity filled with a yellow-colored fluid. Unicameral bone cyst_sentence_0

It is considered to be benign since it does not spread beyond the bone. Unicameral bone cyst_sentence_1

Unicameral bone cysts can be classified into two categories: active and latent. Unicameral bone cyst_sentence_2

An active cyst is adjacent to the epiphyseal plate and tends to grow until it fills the entire diaphysis, the shaft, of the bone; depending on the invasiveness of the cyst, it can cause a pathological fracture or even destroy the epiphyseal plate leading to the permanent shortening of the bone. Unicameral bone cyst_sentence_3

A latent cyst is located away from the epiphyseal plate and is more likely to heal with treatment. Unicameral bone cyst_sentence_4

It is typically diagnosed in children from the aged 5 to 15. Unicameral bone cyst_sentence_5

Although unicameral bone cysts can form in any bone structure, it is predominantly found in the proximal humerus and proximal femur; additionally, it affects males twice as often as females. Unicameral bone cyst_sentence_6

Signs and symptoms Unicameral bone cyst_section_0

Most unicameral bone cysts do not cause any symptoms and are discovered as accidental findings on radiographs or CT scans made for other reasons. Unicameral bone cyst_sentence_7

Large lesions can cause nearby areas of bone to thin, which may result in a fracture and cause pain. Unicameral bone cyst_sentence_8

Cause Unicameral bone cyst_section_1

There is not a specific theory behind the etiology of the unicameral bone cyst, however, according to many researchers and doctors, there is a commonly known theory hypothesized by Jonathan Cohen in 1970. Unicameral bone cyst_sentence_9

Cohen studied interstitial fluid in six children undergoing treatment for unicameral bone cysts. Unicameral bone cyst_sentence_10

He believed that the chemical composition of the fluid found in the bone cyst was similar to the chemical make-up in serum. Unicameral bone cyst_sentence_11

Cohen theorized that the unicameral bone cyst occurs when interstitial fluids in cancellous bones quickly accumulate in one region from blockage. Unicameral bone cyst_sentence_12

One of the other theories is that the cysts result from a disorder of the growth plate. Unicameral bone cyst_sentence_13

Another is that the cysts result from problems with circulation that are caused by a developmental anomaly in the veins of the affected bone. Unicameral bone cyst_sentence_14

The role trauma plays in the development of these cysts is unknown. Unicameral bone cyst_sentence_15

Some speculate that repeated trauma puts the bone at risk for developing a bone cyst. Unicameral bone cyst_sentence_16

This, however, has not been proven. Unicameral bone cyst_sentence_17

Diagnosis Unicameral bone cyst_section_2

X-rays Unicameral bone cyst_section_3

Unicameral bone cysts are found incidentally on X-rays. Unicameral bone cyst_sentence_18

About 90 to 95% of the lesion is found in metaphysics of long bones. Unicameral bone cyst_sentence_19

The cyst is centered, oblong in shape along the long axis of a long bone. Unicameral bone cyst_sentence_20

Rarely, they are large and multicameral and are found in diaphysis. Unicameral bone cyst_sentence_21

When fracture is present, there may be a small bone fragment migrated in the cystic fluid. Unicameral bone cyst_sentence_22

This is called "fallen fragment sign" which is diagnostic of unicameral bone cyst. Unicameral bone cyst_sentence_23

Besides, a bubble migrating upwards (known as "rising bubble sign") is another feature suggesting of unicameral bone cyst. Unicameral bone cyst_sentence_24

Computerized tomography (CT) Scan Unicameral bone cyst_section_4

CT scan shows a thin-walled lesion with pseudo septum (incomplete septum or a septum with perforations that allows communications between two chambers). Unicameral bone cyst_sentence_25

CT scan is used to assess cyst wall thickness and risk of fracture. Unicameral bone cyst_sentence_26

Magnetic Resonance Imaging (MRI) Unicameral bone cyst_section_5

Magnetic resonance imaging scans are used to identify the precise location of the cyst, to see how aggressive the disease is, and to determine the actual shape and size. Unicameral bone cyst_sentence_27

The MRI uses a combination of magnets and radio-frequencies to produce various detailed, computerized images of the cyst and its surrounding body structures. Unicameral bone cyst_sentence_28

Bone scans Unicameral bone cyst_section_6

a nuclear imaging method to evaluate any degenerative and/or arthritic changes in the joints; to detect bone diseases and tumors; to determine the cause of bone pain or inflammation. Unicameral bone cyst_sentence_29

This test is to rule out other cysts (which are quite unusual) Unicameral bone cyst_sentence_30

Treatment Unicameral bone cyst_section_7

If there is a high probability of a fracture resulting from the unicameral bone cyst, then surgical treatment is necessary. Unicameral bone cyst_sentence_31

Specific methods can be determined by the physician based upon the patient’s age, medical history, tolerance for certain medical procedures or medicine, health, and extremity of the disease. Unicameral bone cyst_sentence_32

The treatment can involve or incorporate one or more of the following surgical methods, which are performed by a pediatric orthopedic surgeon: Unicameral bone cyst_sentence_33

Unicameral bone cyst_unordered_list_0

Unicameral bone cyst_description_list_1

  • Surgeons create an incision or opening in the bone to drain out the fluids inside the cyst. After the fluid is drained, a curette is used to scrape the lining tissue out of the lesion.Unicameral bone cyst_item_1_1

Unicameral bone cyst_unordered_list_2

Unicameral bone cyst_description_list_3

  • Bone grafting is proceeded with after curettage; the empty cavity is transplanted with donor bone tissue, bone chips taken from another bone, or artificial material.Unicameral bone cyst_item_3_3

Unicameral bone cyst_unordered_list_4

  • Steroid injection:Unicameral bone cyst_item_4_4

Unicameral bone cyst_description_list_5

  • An injection of methylprednisolone acetate into the lesion helps reduce the levels of prostaglandin. Prostaglandin is a fatty acid that reduces cyst’s ability to be reabsorbed into the bone. To begin an operation using steroids, biopsy needles are placed into the cyst and the interstitial fluids are drained. The cyst is then filled with radiographic contrast to determine the volume and shape of the cyst. If the cyst can be filled, it will be injected with methylprednisolone acetate in several intervals for a time span of six to twelve months. Once the level of prostaglandin decreases, the cyst will be reabsorbed into the bone and disappear. Treatments using steroid injections are preferred over curettage, but there are few risks from the method, which are limited to infection, fracture, and reappearance of the cyst.Unicameral bone cyst_item_5_5

If a patient needs to be treated with surgery, a standard surgical procedure would be called for; the patient would be resting in Fowler’s position, a semi-sitting position, under general anesthesia. Unicameral bone cyst_sentence_34

The exact size, shape, and distance between the acromion to the midpoint of the cyst are measured by a digital radiograph or MRI scan. Unicameral bone cyst_sentence_35

A small, longitudinal skin incision, about 1 cm long, is made at the center of the cyst. Unicameral bone cyst_sentence_36

Next, by using a trephine or drill bit, a small aperture is made inside the incision. Unicameral bone cyst_sentence_37

Fluids contained in the cyst are drained and curved, metal impactors are used to break any septa, or membranes, within the cyst. Unicameral bone cyst_sentence_38

Curettes are then used to remove the entire cyst from the diaphysis. Unicameral bone cyst_sentence_39

After the removal of the cystic membrane, a 95% ethanol solution is injected into the cavity to produce a chemical cauterization to burn away any residual active membrane for 30 seconds and then aspirated. Unicameral bone cyst_sentence_40

Saline solution is then immediately injected into the cavity to wash out any residual ethanol solution and to mitigate any damage to healthy tissue; this irrigation process of ethanol and saline solutions is repeated for another 2 to 3 times. Unicameral bone cyst_sentence_41

A curved impactor is inserted into the cavity and used to penetrate the boundary between the cyst and bone marrow; the intentional penetrations will allow bone marrow cells to migrate into the cavity to produce a source of osteoinductive cells, cells that induce bony growth. Unicameral bone cyst_sentence_42

Furthermore, the cavity is completely filled with bone graft substitute, such as calcium sulfate. Unicameral bone cyst_sentence_43

Finally, one cannulated screw is placed into the aperture. Unicameral bone cyst_sentence_44


Credits to the contents of this page go to the authors of the corresponding Wikipedia page: en.wikipedia.org/wiki/Unicameral bone cyst.