What Is the Ulna?

The ulna is the stable bone of the forearm. It is the long bone that is located on the inside of the two forearm bones and is integrated at two ends.

The ulna is the stable bone of the forearm. It is the long bone that is located on the inside of the two forearm bones and is integrated at two ends.

Chinese name

Ulna

Foreign name

ulna

Department

orthopedics

Nature

Medial forearm bone

Pinyin

ch g

Anatomical structure and composition of ulna

Its proximal end has a half-moon-shaped sunken groove. There are two protrusions at the upper and lower ends of the notch, the upper part is the beak and the lower part is the crown. The shallow depression outside the coronary process is the radial notch and the related head of the radial head. Under the coronoid process there is a rough ulnar tuberosity. The ulnar body is triangular in shape, and the outer edge is sharp so that the interosseous is opposite to the interosseous of the radius. The distal end is small and disc-shaped, called the ulna head. A small round protrusion from the medial side of the ulnar head is the ulnar styloid process. The position of the ulnar styloid process is 1 cm higher than the radial styloid process.

There is a distinct condyle under the radial incision on the lateral side of the ulna, called the supinator. There is a depression between the supinator condyle and the distal part of the coronary process, the supinator fossa. The deep part of the supinator is attached to the condyle and the fossa. The ulnar body is thick and cylindrical at the proximal end, but gradually tapered toward the distal end and gradually reduced in diameter. At its narrow distal end it suddenly becomes slightly swollen, forming a disc-shaped head and a small conical styloid process. Note that the ulnar head is distal (such as on the wrist). Although the forearm has a slight abduction-adduction "swing" during pronation and supination, the joint between the ulna and humerus only allows the elbow to flex and extend.

The ulna olecranon may fracture due to direct violence, but it is more common that the triceps brachial muscles contract and tear off where they stop.

Ulna imaging structure

1. The ulna is upright on the orthosis, the upper end of the ulna is swollen, and the protruding olecranon is not square. Most of the eagle's beak overlaps with the humerus tackle and is densely developed. The coronal process is located below the eagle's mouth, and it develops into a slightly convex convex dense line, so the curved dense line shows the orthotopic image of the coronal process. The arc dense line itself is the articular surface above the coronoid process, which corresponds to the lower edge of the humerus pulley, and forms the humerus-ulnar joint, and sees the joint space. The radial notch on the outside of the coronary process is sagittal and cannot be fully displayed, but it corresponds to the radial head and forms a proximal radius ulnar joint. This joint is often not overlapped due to the overlap of the two bones, or it shows only a less transparent Partial gap shadow.

The ulna is a tubular bone shadow with thick cortex on both sides and a bone marrow cavity. The medial cortex is slightly narrower but clear, and the edges of the lateral cortex are blurred. A lightly developed interosseous shadow can be seen along its edges.

The ulnar head and the ulnar styloid process at the lower end of the ulna are clearly visible. The ulnar head corresponds to the ulnar notch of the radius, forming the distal radius ulnar joint. Most of the two bones overlap each other, and sometimes the joint space is visible. The joint disc below the ulna head and the wrist bone cannot be visualized, and the distance between the two on the X-ray is wide.

Ulna related diseases and treatment

1. Single ulna fractures are rare. If the ulna and radial joint dislocations are combined, improper treatment will cause residual pain and affect the forearm rotation function. Most of them are direct violent injuries, which mostly occur in the lower 1/3 of the ulna, and the lower 1/3 fractures are accompanied by severe angulation and overlapping displacement. Attention should be paid to the dislocation of the lower ulnar radial joint. And lower ulnar radial joint to avoid missed diagnosis, if necessary, take forearm pronation and supination radiographs to confirm the diagnosis. The purpose of ulna fracture with ulnar radius joint treatment is to ensure the normal movement of the forearm. Clinically seen ulna fractures are mostly severe comminuted fractures with rotation and angular deformities. Closed reduction is often difficult to achieve satisfactory reduction. Forearm muscle movement, fractures are not easy to maintain in the initial reduction position, affecting the treatment effect.

2. The surgical method is anesthesia with brachial plexus block, and an inflatable tourniquet is applied during the operation. Take a small incision on the dorsal side of the ulna, peel off the periosteum in a small area, and expose the fracture end. If the fracture is not serious, fix it with a compression plate after satisfactory reduction. When the fracture is severe, there is a serious angle or rotation deformity, do not force the anatomical reduction, restore the ulnar line of force, and fix it with a 2 ~ 3mm bone needle. Correct the angulation and rotation deformity, take the autologous iliac bone graft when there is obvious bone defect, understand the reduction and stability of the lower ulnar and radial joint under the perspective of C-arm X-ray machine. If there is instability, fix it with a fine Kirschner wire. Ulnar radial joint. After the operation, the incision is sutured.

3. Postoperative treatment can avoid external fixation by internal fixation with a compression steel plate. External fixation of the plaster support is performed when the bone needle is fixed. Antibiotics are routinely applied to prevent infection and early guidance of wrist function exercises. The Kirschner wire of the lower ulna radial joint was removed 4 weeks after the operation.

Research on ulna related clinical technology

Ulna fractures are common clinical fracture types, which are mainly manifested by local swelling, pain and deformity of the ulna, and there are obvious bone fricatives and forearm rotation dysfunction. In the past, the reduction plate was used for internal fixation in the treatment of ulna fractures, but it requires a long incision in the patient's fracture, and the plate is then fixed with screws, which can cause the surgical incision to be too long, resulting in poor fracture healing and incision infection. And serious problems such as failure of fixation, therefore, the choice of a reasonable and effective surgical method has become an urgent problem in the treatment of ulna fractures. With the continuous development of medical technology, various types of minimally invasive surgery are continuously applied in orthopedic treatment. It mainly uses the role of internal fixation to reduce the fracture and treat the fracture without affecting the normal growth of broken bones. In order to better protect the soft tissue of the fracture and reduce the incidence of postoperative complications. Among them, minimally invasive plate internal fixation is one of the common minimally invasive internal fixation methods, which is minimally invasive and safe, and can accelerate postoperative fracture healing, reduce the incidence of complications such as infection and nonunion.