What is Cancellous Bone?

Bone is an organ with high-density connective tissue with a unique structure. It is mainly divided into cortical bone and cancellous bone in structure. Cancellous bone accounts for 20% of the human bone mass, but constitutes 80% of the bone surface. Cancellous bone has a lower bone density than cortical bone and is highly elastic. The scaffold structure of cancellous bone helps maintain skeletal shape and resist pressure, and forms most of the central axis bones such as skull, ribs, and spine.

Cancellous bone

Human bone is divided into bone cancellous and

[Introduction]

Cancellous bone transplantation has the advantages of large osteogenic stimulation, fast crawling replacement process, strong anti-infective power, and can form fragments to fill any cracks between bone ends. Therefore, it has a wide range of applications. Its disadvantages are soft texture and weak internal fixation. Therefore, it is often used clinically with cortical bone transplantation or metal internal fixation. Generally, cancellous bone transplantation is mostly used for bone cavity filling, joint fusion, fracture nonunion, bone defects, etc. formed after bone tumors or inflammation scraping. In addition, cancellous bone fragments can also be used to reduce fractures of poor blood supply (such as in the case of fractures below the 1/3 of the tibia).

The sacrum has more high-quality cancellous bone. When a large amount of cancellous bone is needed, it can be taken from the sacrum; it can also be taken from the ribs. When a small amount of cancellous bone is needed, it can be taken near the end of the diseased bone, but it contains more fat and is of poor quality.

[Indications]

1. Bone defects caused by bone tumor resection or injury.

2. Congenital tibial pseudoarthrosis, or pseudojoint caused by fracture nonunion.

3. A variety of benign bone tumors or inflammatory lesions can be left after surgery and can be filled with bone graft to restore the solidity of the bone.

4. Various internal and external joint fusions, limb lengthening, osteotomy, and fractures with poor blood flow for incision and reduction, bone grafts can fill defects, promote healing, and strengthen fusion.

5. Congenital dislocation of hip joints with acetabular cap or hip bone resection.

6. Poor blood supply fractures, such as femoral neck sac fractures, or ischemic osteonecrosis, such as adult femoral head necrosis, may be anastomosed bone grafts to replace sclerotic bone, increase local blood supply, and promote bone healing.

[Preoperative preparation]

1. Prevention of wound infection is an important guarantee for the success of bone transplantation. The graft's anti-infective power is very weak. Once infected, the graft bone is soaked with pus, which will cause necrosis and cause failure. Preventive measures are: skin must be prepared strictly for the receiving and donor areas; the storage of bone must be strictly sterilized; the patients with bone and soft tissue infections must be cured 3 to 6 months after the infection is cured Bone graft surgery, otherwise the surgery is likely to stimulate local latent bacteria and make the infection recur. Such patients should be treated with antibiotics before surgery. Cancellous bone graft or anastomotic bone graft should be used as much as possible during the operation.

2. The soft tissues surrounding the bone-receiving area and the blood flow to the bone must be abundant and the growth must be strong to ensure the healing process of the bone graft. If there is extensive scarring of local skin and soft tissue, blood flow is bound to be poor, and the content after bone transplantation increases, skin suture is difficult, and infection is easy to occur, forming sinus tract. Therefore, the scar should be removed before surgery for skin flap transplantation to create conditions for the healing of bone grafts.

3. Many patients who need bone grafting have undergone multiple operations or long-term external fixation, resulting in muscle atrophy of injured limbs, decalcification and loosening of bone, joint movement restrictions to varying degrees, poor blood circulation, and low anti-infective power. The tissue growth ability is also poor. External fixation, which is an essential period of time after bone grafting, will cause muscle atrophy and joint stiffness. Therefore, functional exercise and physical therapy should be performed for a period of time before surgery. For patients with non-displaced lower limb fractures that do not heal or bone defects, functional exercises can be performed under the protection of a stent or external fixation.

4. Take an x-ray film before surgery to understand the condition of the diseased bone, and design the surgery according to the condition (including the bone graft site, the size of the bone graft slice and the bone graft method). If anastomosed bone graft is to be prepared, the full length of the transplanted bone should be taken before the operation and the lateral x-rays should be taken to select the site and length of the bone graft.

5. Prior to anastomotic bone transplantation, an ultrasonic blood flow meter should be used to detect the presence and blood flow of the main arteries in the donor and recipient limbs in order to design the surgery. Generally, the arteries of the receiving area are mostly anastomized by branches of the main arteries of the limb, such as the deep femoral artery of the femoral artery, the internal and lateral femoral arteries, and the like. If there are 2 main arteries in the receiving area, such as the ulnar and radial arteries, the anterior and posterior tibial arteries, one of the main arteries can also be selected for anastomosis. The prerequisite must be confirmed by the ultrasound blood flow meter or clinical examination. Good blood supply. The superficial veins are generally used for anastomosis of the veins in the receiving area, such as the cephalic vein, the expensive vein, the great saphenous vein, the small saphenous vein, and their branches. Therefore, the superficial vein of the affected area should be checked for damage or inflammation before surgery. It is used as a puncture recently. The superficial vein for infusion cannot be used as a receiving vein.

[anesthesia]

Lower limbs are anesthetized with spinal or epidural anesthesia, and upper limbs are anesthetized with brachial plexus.

[Surgery steps]

Cancellous bone transplantation is often used in conjunction with other surgeries to fill bone defects and promote healing.

1. Select a suitable incision according to the fracture site to reveal the non-healing site of the fracture, thoroughly remove the scar tissue and the hardened bone at the folded end, and chisel the medullary cavity at both ends, and use the intramedullary nail, steel plate or cortical bone plate for internal fixation. [figure 1]. Bone defects fill all cracks and corners with cancellous bone fragments and gently tighten. Finally, the periosteum and incision are sutured.

2. After the benign bone cyst or bone tumor is exposed, first drill holes around the lesion, drill through only one side of the cortical bone, each drill is arranged in a rectangular shape, and then use a bone knife to cut the bone between the holes to remove one piece. Cortical bone, after scraping out the diseased tissue, fill in cancellous bone. If the lesion is located in the weight-bearing area, an appropriate amount of cortical bone graft should be added, and it should be lightly tightened and sutured in layers [Figure 2].

[Intraoperative precautions, postoperative management]

Same bone supplantation and internal fixation.