What is Dislocation of the Lunar Bone?
This dislocation represents the secondary displacement of the lunate bone after the spontaneous reposition of the perilunar dislocation of the hand.
Symptoms Dislocation of the Lunate Bone
In the area of the carpal joint diffuse swelling, soreness; movements are limited. Palpation on the site of the lunate bone on the back side reveals a retraction, and on the palmar bone a protrusion. Possible sharp pain due to pressure of the displaced bone on the median nerve. The fingers are in the flex position.
Diagnosis Dislocation of the Lunate Bone
An accurate diagnosis can be made on the basis of x-ray data of the carpal joint in 2 projections. Basic information gives a radiograph in the lateral projection.
Treatment for Dislocation of the Lunar Bone
Reduction of the dislocation of the lunate bone using a closed method is performed under conduction anesthesia of the brachial plexus area or under general anesthesia with a significant extension of the wrist joint by a distraction apparatus. After stretching the joint, the surgeon with the thumbs displaces the lunate bone from the palmar side into the joint cavity. Before removal of the device make a control X-ray. If reposition of the dislocation has occurred, the apparatus is removed and the dorsal plaster of the longget is applied from the elbow to the metacarpophalangeal joints. With instability of the lunar bone, it can be fixed transarticularly with a Kirschner needle. Closed reduction of dislocation is possible no later than 10-14 days after injury. At a later date, surgical treatment is indicated. With an increase in the limitation period of injury, the difficulties of even open reduction increase, as aseptic necrosis begins to develop as a result of malnutrition in the bone.
Surgical treatment is indicated in cases where it is impossible to close the control of fresh dislocations even with the help of distraction devices. Apply operation also at old dislocations. The most favorable conditions for reduction can be created by pre-imposing the distraction apparatus (Volkov-Oganesyan, Ilizarov) and stretching the carpal joint for 5-10 days. The duration of the distraction depends on the age of injury. The required amount of distraction is determined by radiographs. At stage II, open dislocation through the rear access is performed. The approach to the wrist joint is carried out in the interval between 3 m and 4m osteofibrous channels, in which the extensors pass. The transverse ligament is cut longitudinally in this gap. General extensor fingers fingers divert to the elbow side, and the rest in the radial. Dissect the capsule of the carpal joint in the projection of the lunar bone and its bed is cleaned of scars. Gently with the help of tools produce the reduction of the lunate bone, and then reduce the degree of stretching of the carpal joint.
For the prevention of the development of aseptic necrosis of the lunar bone create an additional source of blood supply in Grishin and Divakov. For this purpose, the skin incision is prolonged over the second interpine space. Atraumatically secrete the vascular bundle, which includes the second dorsal metacarpal artery and the accompanying veins with the surrounding perivascular tissues from the base of the metacarpal bones to their heads. The distal end of the vascular bundle is tied up. In the lunar bone along its axis in the direction from the dorsum to the palmar is drilled channel. A thin catgut filament is tied to the distal end of the vascular bundle, and its second end is inserted into the eye of the needle of the conductor. With the help of a conductor, the vascular bundle is implanted into the channel of the lunate bone, and the end of the thread is tied on a gauze ball. Then the wound is sutured in layers, the device is removed and the back gypsum longhuet is applied for 4 weeks in the bending position at an angle of 20-30 °.
When the vascular bundle is transplanted into the lunate bone, the blood supply of which is always affected or completely disrupted during dislocation, its revascularization occurs due to the growth of the vascular network of perivascular tissues into the intergrowth spaces. The total duration of disability during the dislocation of the lunar bone 1.5-2 months.