Lunate Dislocation

　　Dislocation is often caused by indirect external force, such as a fall with the palm on the ground, the wrist in extreme extension, the gravitational force from above and the reactive force from below compressing the distal radius bones and the capitate bone, widening the palmar space between the radius and the capitate bone, and the rupture of the palmar ligament and joint capsule between the capitate bone and the lunate, causing the lunate to dislocate to the palmar side.

　　If the lunate remains in its original position while other carpal bones are completely dislocated, it is called a lunate periarthrodial dislocation.

　　Lunate dislocation is divided into three types according to the degree and location of injury:

　　1、Rupture of the radial-lunate posterior ligament or avulsion fracture of the posterior angle of the lunate, after dislocation to the palmar side, with the convex side facing backward and the concave side facing forward.

　　2、After the posterior ligament is torn, the lunate rotates 270° and is located in the anterior distal part, with the concave side facing backward and the convex side facing forward.

　　3、With greater external force, both the radial and ulnar ligaments are ruptured, and the lunate is displaced to the palmar side of the distal radius, with the convex side facing backward and the concave side facing forward. If the lunate is connected to the anterior ligament, the lunate has vitality; if both the anterior and posterior ligaments are ruptured, necrosis may occur.

　　The complications of this disease include the following types:

　　1、Median nerve palsy:Early reduction can allow the median nerve to recover completely early. If the reduction is delayed, the recovery may not be complete, but other treatments are rarely needed.

　　2、Sudeck atrophy:This is a common complication of the disease;

　　3、Ischemic necrosis:It can lead to lunate collapse and secondary osteoarthritis, the latter progressing rapidly. All patients with lunate dislocation should have an X-ray examination every month within the first 6 months after injury to timely detect this complication. If detected early, the lunate can be excised to prevent progressive osteoarthritis. For many cases, especially in late-stage patients, wrist joint arthrodesis is倾向于. Note that wrist injuries without lunate dislocation may also have similar X-ray findings (Kienbock's disease). It is more common in physical laborers, such as carpenters, shoemakers, and those who frequently use hammers.

　　The main manifestations of this disease are swelling of the wrist, causing the patient's hands to clench. When the lunate is dislocated, there is a significant shortening of the third metacarpal head on the affected side, limited wrist movement, difficulty in finger flexion, inability to extend the wrist joint, tenderness at the palmar-wrist crease, and palpable lunate extrusion. The wrist deviates towards the ulna, and there is marked pain when tapping the fourth metacarpal head. The median nerve may also be compressed, leading to numbness on the radial side of the palm.

　　This disease is mainly caused by trauma, so safety should be paid attention to in daily life to prevent accidental injuries. In addition, there are several points to note in diagnosis and treatment: due to the high risk of lunate avascular necrosis after dislocation, early and clear diagnosis, as well as timely closed reduction or percutaneous Kirschner wire撬拨复位, are crucial to prevent lunate avascular necrosis. For cases with old or long-distance dislocation, as the palmar and dorsal ligaments have been ruptured, the blood supply to the lunate has been interrupted, making it a dead bone, which should be excised.

　　In addition to clinical manifestations, X-ray examination can provide evidence for diagnosis, mainly including anteroposterior view and lateral view.

　　1. X-ray anteroposterior view:The arrangement of the wrist bones is disordered, the shadow of the capitate bone overlaps with that of the lunate, the scapholunate interval is increased, the long axis of the scaphoid bone is shortened, showing a cortical ring sign or scaphoid rotation, the lunate dislocation loses the quadrilateral structure and presents as a triangular shadow.

　　2. X-ray lateral view:When there is a dorsal dislocation around the lunate, the third metacarpal, the capitate bone, and the lunate lose the normal common axis relationship, the axis of the third metacarpal and the capitate bone is located on the dorsal side of the axis of the lunate and the radius. On this basis, when the lunate tilts towards the palmar side, it indicates a dynamic dorsal dislocation around the lunate. When the lunate is dislocated to the palmar side, the common bearing relationship between the third metacarpal, the capitate bone, and the radius remains unchanged, while the lunate is located on the palmar side of the axes of the above bones.

　　1. Foods to eat for the diet of lunate dislocation: what is good for the body:

　　Increase nutrition, eat more protein-rich foods such as fish, eggs, soy products, and appropriately increase calcium. Drink more water, eat more vegetables and fruits such as green vegetables, celery, bananas, etc.

　　2. Foods that are best not to eat:

　　Avoid spicy foods: such as chili, mustard, etc. Habits such as smoking and drinking should be戒除.

　　1. Fresh lunate dislocation, for type 1 and 2 dislocation, early manipulation reduction should be performed as soon as possible. Pull the affected hand towards the distal side, extend the wrist joint, and then press the lunate back to its original position. Fix the wrist joint in a掌屈45° position for one week and then flatten and fix it for two weeks. Practice activity after removing the external fixation. For type 3 dislocation, due to the complete loss of blood supply caused by the rupture of the anterior and posterior ligaments, necrosis may occur, and early excision should be performed. Dislocation around the lunate is not difficult to manipulate, and postoperative management is the same as before.

　　2. Old traumatic dislocation of the lunate. For cases of type 1 and 2 dislocation after 3 to 4 weeks of injury, manipulation reduction is not easy to succeed. Open reduction should be performed. Postoperative management is the same as before. If degenerative changes in the cartilage are found during surgery, it should be excised. Activity can be started a few days after fixation. For type 3 dislocation, excision should be performed.