Congenital radial bone aplasia

　　The true cause of congenital radial bone agenesis is still unclear. According to the Gegenbauer theory, the upper limb is composed of a main ray and four secondary rays. The radius, navicular bone, trapezium bone, first metacarpal bone, and two phalanges of the thumb make up the first secondary ray. When the development of the first secondary ray is suppressed, congenital radial bone agenesis occurs, and the thumb is often absent as well.

　　Congenital radial bone agenesis is a relatively rare congenital malformation, but it is more common than ulna agenesis. This condition often coexists with other congenital malformations, such as: hydrocephalus, cleft lip, cleft palate, rib malformation, underdeveloped or atrophic lungs, hernia, scoliosis or kyphosis, hemivertebrae, anal atresia, clubfoot, Fanconi syndrome with severe anemia, etc.

　　The degree of malformation of congenital radial bone agenesis ranges from simple underdevelopment of the radial bone to complete absence of the radial bone. What are the symptoms of congenital radial bone agenesis? Let's see the introduction by the experts together.

　　1. This malformation can be divided into three types:

　　Type A is characterized by underdevelopment of the radius

　　The distal growth site of the radius is absent. The ossification of the epiphysis is delayed, the distal part of the radius is short, and the styloid process of the radius is at the same level as the styloid process of the ulna. The proximal part of the radius epiphysis has a normal relationship with the elbow joint. The shortening of the radius is relatively mild, the navicular bone and the trapezium bone are underdeveloped, the thumb is small or absent, the wrist is radially deviated, but relatively stable.

　　Type B is characterized by the partial absence of the radial bone

　　The middle and distal parts of the radius are underdeveloped, while the proximal part of the radius is normal, which maintains a certain degree of stability for the elbow joint. The radius is underdeveloped, fused with the ulna, forming one type of ulna-radiate bone fusion, and sometimes the radius fuses with the capitulum of the humerus. The ulna is shortened, thickened, and curved, pointing towards the radius. The wrist joint is unstable, and the hand is tilted towards the radial side.

　　Type C is characterized by the complete absence of the radial bone

　　This type is the most common, accounting for about 50% of the畸形. Due to the absence of radial bone support at the wrist, the soft tissues on the radial side of the forearm are severely contracted, and the hand forms a 90° or more radial deviation with the forearm. When the elbow is flexed, the hand may even be parallel to the upper arm. All radial bones are completely absent, including the navicular bone, the first metacarpal bone, and the thumb bone. If the thumb is present, it is often underdeveloped or floating. The humerus is shortened, the capitulum of the humerus is underdeveloped or absent, and the ossification of the distal humerus epiphysis is delayed.

　　2. There is a fibrous connection between the ulna and the wrist, without articular cartilage covering, the wrist joint subluxates towards the radial and palmar sides, and the soft tissue contracture on the radial side of the forearm is obvious. If the deformity is not treated, as the skeleton grows, the deformity becomes more severe. The metacarpophalangeal joints are hyperextended, and flexion is restricted. Fixed flexion deformities of the proximal interphalangeal joints. The X-ray films of the proximal interphalangeal joints and metacarpophalangeal joints show normal. Joint stiffness may be related to abnormal extensor muscles. The flexion of the finger joints gradually decreases from radial to ulnar.

　　In 1/4 of the cases, the elbow joint is rigid in the extended position. If the elbow joint extension contracture cannot be corrected, it is considered a contraindication for wrist centralization surgery.

　　Muscles are also involved. The radial extensor muscle is absent or hypoplastic, fibrotic, or fused together. The pronator quadratus, radial wrist flexor muscles, brachioradialis, and supinator muscles are often absent. However, the interosseous muscles, lumbricals, and hypothenar muscles are generally not involved.

　　The extensors of the wrist and fingers are normal, but often fused together. The superficial flexor muscle of the fingers varies greatly, can be hypoplastic, fibrotic, or fused with the deep flexor muscle of the fingers.

　　The long head of the biceps brachii is absent, but the short head exists, but the insertion is abnormal, often attached to the joint capsule or residual radial or humeral epicondyle. The pectoralis major, minor, and deltoid muscles exist, but the insertion is abnormal or fused with the deltoid or biceps muscle.

　　3. Nerve involvement, axillary and ulnar nerves are normal, the musculocutaneous nerve is often absent, and the radial nerve often terminates at the elbow, with the radial side of the hand sensation supplied by the median nerve. The median nerve is thicker than normal, located under the deep fascia on the radial side of the forearm. Pay attention not to damage the median nerve during surgery.

　　4. Vascular involvement, with the ulnar artery present, often becomes the main blood vessel supplying the forearm and hand. The interosseous artery develops well. The radial artery and palmar arch are abnormal, and the degree of vascular involvement is related to radial hypoplasia. The radial side of the forearm is supplied by the interosseous artery, originating from the ulnar artery, and accompanying the median nerve. The radial artery atrophy or absence.

　　Congenital radial bone aplasia is a congenital disease with no effective preventive measures. Early diagnosis and early treatment are the key to the prevention and treatment of this disease. At the same time, attention should be paid to distinguishing whether it is a simple radial bone aplasia or due to other congenital malformations that cause radial bone aplasia, so as to carry out etiological treatment and allow the child to recover health as soon as possible.

　　Congenital radial bone aplasia can be divided into three types: Type A is radial bone hypoplasia, Type B is partial radial bone aplasia, and Type C is complete radial bone aplasia. Among them, Type C is the most common. There is no related laboratory examination for congenital radial bone aplasia. The examination methods for this disease include the following two.

　　1. Ultrasound examination:

　　The lesion of congenital radial bone aplasia occurs at the distal end of the radius, and the muscles that control the wrist also become contracted and deformed, causing the forearm to shorten, the ulna to bend towards the radius, and the wrist joint and hand to deform radially. Some scholars call it 'deformed hand'. Ultrasound examination can show a specific deformity image with the absence of the radius or obvious shortening, a short and bent forelimb, and the hand inclined medially.

　　2. X-ray examination:

　　Clinically, bilateral humerus ulna radial bone anteroposterior and hand anteroposterior radiographs are often performed, which can detect the absence of the radial bone on the affected side, and at the same time, other bone deformities may occur, such as shortening of the ulna, or absence of metacarpal and phalanges, etc. At this time, the hand is inclined to the radial side, forming a vertical shape with the ulna shaft.

　　Patients with congenital radial bone aplasia should have a diet that is light, easy to digest, with an emphasis on eating more vegetables and fruits, and a reasonable dietary arrangement, ensuring adequate nutrition. In addition, patients should also pay attention to avoiding spicy, greasy, and cold foods.

　　Congenital radial bone aplasia, also known as peripheral radial hemilimb deformity or radial club hand, is a relatively rare congenital malformation. How to treat congenital radial bone aplasia? With this question in mind, let's take a look at the introduction below.

　　How to treat congenital radial bone aplasia? Patients with type A use plaster correction to achieve the purpose of correcting the radial soft tissue contracture of the forearm. Passive extension exercises of the wrist joint are performed to maintain the functional position of the hand. When 8 to 10 years old, if the radial shortening progresses and affects the function of the wrist, radial 'Z' osteotomy and complete soft tissue release surgery should be performed. After the operation, the upper limb plaster is fixed at 60° to 70° elbow flexion, the forearm supinated position, and the wrist joint functional position. The plaster is fixed for 8 to 10 weeks.

　　For patients with type B or C, due to the instability of the wrist joint, severe radial deviation and palmar flexion of the hand, immediate treatment should be given after birth to prevent soft tissue contracture. After plaster correction, if the hand reaches a neutral position, it should be changed to night splint fixation, and at the same time, passive flexion activities of the elbow joint, palmar flexion of the metacarpophalangeal joint, and hyperextension activities of the proximal interphalangeal joint should be performed. If the radial deviation and wrist instability of the hand worsen, affecting the function of the hand, wrist centralization surgery should be performed, with the ulnar and dorsal joint capsules of the wrist tightened, the tendons of the hand transferred, the radial soft tissue released, and if necessary, ulnar wedge osteotomy can be performed to correct the curvature deformity. The best time for surgery is during infancy.

　　The lesion of congenital radial bone aplasia occurs at the distal end of the radius, and the muscles that control the wrist also become contracted and deformed, causing the forearm to shorten, the ulna to bend towards the radius, and the wrist joint and hand to deform radially. Some scholars call it 'deformed hand'. Ultrasound examination can show a specific deformity image with the absence of the radius or obvious shortening, a short and bent forelimb, and the hand inclined medially.

　　Clinically, bilateral humerus ulna radial bone anteroposterior and hand anteroposterior radiographs are often performed, which can detect the absence of the radial bone on the affected side, and at the same time, other bone deformities may occur, such as shortening of the ulna, or absence of metacarpal and phalanges, etc. At this time, the hand is inclined to the radial side, forming a vertical shape with the ulna shaft.

　　Once congenital radial bone aplasia occurs, it is necessary to go to a regular hospital for examination and treatment in a timely manner.