1.General information
Strictly speaking, the lunate bone in ancient times (and in the modern Latin nosological lexicon) is called “lunar”: os lunatum. However, its crescent shape resembles a crescent moon rather than a lunar disk, and therefore in many languages its name was later transformed into “semilunar bone” (the semilunar bone, le semi-lunaire os, etc.). This is a relatively small carpal bone, which is located at the base of the palm; It is separated from the radius by the scaphoid bone; nearby are the trapezoid and other bones of the wrist joint.
In general, the lunate bone does not differ in anything remarkable, with one exception: of all carpal dislocations recorded in traumatology, the largest share is due to dislocation of the lunate bone. It is located in such a way that, while providing the unique mobility of the human hand, it is also the most vulnerable to “careless” impacts and strains.
A must read! Help with treatment and hospitalization!
Clinical picture. Symptoms of subluxation of the radial head
Whatever the reason that caused the damage, according to others, the child screams in pain, after which he immediately stops moving his arm and has since held it in a forced position, stretched along the body and slightly bent at the elbow joint.
When you try to force the child to move his arm, he protests and complains of pain in the elbow, and sometimes in the wrist area. When collecting anamnesis, you should always try to understand the mechanism of injury and remember that subluxation occurs when there is a sharp stretch along the axis of the limb. If it is possible to establish the fact of such a sprain, the doctor immediately receives very valuable instructions for diagnosis.
The clinical picture of subluxation of the radial head is always typical. The arm hangs along the body like a paralyzed one, in a position of slight flexion at the elbow joint and pronation. An attempt to make movements in the elbow joint causes the child to cry, since the movements are painful. However, you can carefully perform slow flexion and extension at the elbow, while rotational movements are impossible (pain!). With palpation, it is sometimes possible to determine that pressing on the head of the radial bone is painful, but no visible changes are noted in this area. No pathological changes are visible on radiographs.
2. Reasons
There is a concept of “perilunate dislocation”: in this case, the lunate bone remains in its position, and the rest are displaced to the rear and proximally (towards the elbow). These dislocations occur five times more often than lunate dislocations and account for more than 90% of all carpal dislocations. However, with spontaneous reduction of the perilunar dislocation, when the other bones fall into place, a secondary displacement of the lunate occurs, which in its new position rotates like an “overturned cup” and ceases to correspond in shape to the neighboring bones. It is this condition that is mentioned above as the most common wrist dislocation.
Dislocation of the lunate bone is one of the typical fall injuries, when the body weight multiplied by acceleration falls almost entirely on the overextended palm (the hand takes an overextended position, for example, in an acrobat, gymnast, circus performer - when they do a straight arm stand or a back somersault with support on hands). A similar dislocation can be obtained in a “defensive” movement with straight arms, trying to stop, for example, a rapidly approaching object, as well as in an accident and under other similar circumstances.
Visit our Traumatology and Orthopedics page
Dislocations of the hand bones account for 5% of the total number of dislocations. The cause of injury is usually a fall with emphasis on the hand or a direct blow to the wrist joint. The characteristics of a hand dislocation are determined by the anatomical structure of the joint, the position of the hand and the direction of action of the forces causing the injury. Dislocations of the hand bones are classified into true, perilunate, perilunate-lunar, peritriquetral-lunar, transscaphoid-perilunar, transscaphoid-translunate, dislocations of the metacarpal bones and phalanges. The clinical picture of a hand dislocation consists of swelling and pain in the area of the dislocation; upon examination, the presence of deformity is revealed. The diagnosis is confirmed using radiography.
True hand dislocations
Rarely observed. With true dislocations of the hand, the articular surfaces of the upper row of carpal bones, together with the hand, are completely displaced in relation to the articular surface of the radius. More common is complete dorsal dislocation of the hand, less common is complete palmar dislocation. Complete dislocations of the hand can be combined with a fracture of the radius and styloid processes.
Perilunate dislocations of the hand
They make up about 90% of the total number of hand dislocations. Occurs when falling with emphasis on the hand or sudden forced extension of the hand. With a perilunar dislocation of the hand, the contact between the lunate and radius bones is maintained, and the remaining bones of the wrist are displaced to the rear and to the center. Perilunar dislocation of the hand is sometimes accompanied by fractures of the triquetrum, scaphoid bones and styloid processes.
Perilano-lunar dislocations of the hand
The lunate and scaphoid bones remain in place. The remaining bones of the wrist move toward the back and center.
Peritriquetral-lunar dislocations of the hand
It is extremely rare. The triquetrum and scaphoid bones remain in place. The remaining bones of the wrist move toward the back and center.
Transscaphoid-perilunar dislocations of the hand
Must be combined with a fracture of the scaphoid. With this dislocation, the lunate bone and the central fragment of the scaphoid maintain their position. The remaining bones of the wrist, together with the distal (located further from the center) fragment of the scaphoid bone, are displaced towards the rear.
Transscaphoid-translunate dislocations of the hand
Accompanied by a fracture of the lunate and scaphoid bones. The proximal (central) bone fragments remain in place, while the distal ones, together with the rest of the bones of the wrist, are shifted to the rear and to the center.
Treatment of hand bone dislocations
Patients with suspected wrist dislocation should immediately contact the traumatology department or emergency room. Reduction of fresh dislocations is performed by a traumatologist under anesthesia, local or conduction anesthesia. The patient's arm is bent at the elbow joint at a right angle. The assistant holds the limb in the lower third of the shoulder. The traumatologist pulls the forearm along the axis, and after stretching the joint, presses on the bulging area located on the dorsum of the hand.
After reduction, the hand is bent at an angle of 40°. The patient is placed in a plaster cast from the elbow joint to the base of the fingers. After two weeks, the hand is transferred to a neutral position and fixed again for two weeks.
If instability in the joint is determined after reduction, fixation is performed with Kirschner wires. If closed reduction is impossible and there are long-standing dislocations of the hand, a special distraction device is applied.
Compression of the median nerve is an indication for urgent surgical treatment. The postoperative period of fixation for transscaphoid-perilunar dislocations is 3-4 months, for other hand dislocations - 4-6 weeks.
Immediately after reduction of the dislocation, the patient is advised to move his finger joints.
After removing the plaster splint, physiotherapy, massage and therapeutic exercises are prescribed to develop the wrist joint. To the section “Treatment of joint dislocations”
3. Symptoms and diagnosis
The most characteristic symptoms of any dislocation are pain, swelling and limited mobility in the joint. There is usually a noticeable depression on the dorsal side of the wrist joint, and an abnormal convexity on the palm side. The fingers, as a rule, are in a forced half-bent position.
Particularly intense pain is observed in cases where the displaced lunate bone exerts mechanical pressure on the median nerve.
An experienced traumatologist recognizes or at least assumes a dislocation of the lunate bone already during examination, however, due to the risk of associated complications or fractures, the final diagnosis is established only by x-ray - pictures are necessarily taken in two projections, the more informative of which is, as a rule, the lateral one.
About our clinic Chistye Prudy metro station Medintercom page!
Symptoms of dislocations
A dislocation of the wrist joint is the emergence of the articular part of the bone from its cavity, in which the articular capsule and ligaments are disrupted.
- When a joint dislocates, it changes shape.
- Motor functions are associated with severe sharp pain, they are limited or completely blocked.
- The area of the joint and proximal hand are swollen.
- Dorsal dislocations are characterized by a bulge on the back of the hand. If the median nerve is compressed, sensory impairment occurs.
4.Treatment
Trying to correct a dislocated lunate on your own is just as dangerous as ignoring the need for trauma care. It’s hard to believe, but there are still cases of chronic dislocations of the lunate bone, and, naturally, such situations are the most difficult. The fact is that with a significant change in the configuration of the joint, serious disturbances in the blood supply occur, which in turn lead to ischemia and then to tissue necrosis. In such cases, the only choice is a complex open operation (including the creation of an alternative blood supply circuit), which requires preliminary distraction (stretching) with a special apparatus for several days. The pathological mobility of the lunate bone is in some cases blocked by the transarticular insertion of a Kirschner wire.
However, closed reduction is a rather complex manipulation, which is usually performed under conduction anesthesia, and in some cases under general anesthesia, since the lunate bone can be reduced only with significant hardware distraction of the joint. The restoration of anatomical positions is controlled radiographically, then the distractor is removed and a long plaster splint is applied (from the elbow to the base of the fingers) on the back of the hand.
The total duration of the period of incapacity for work in complicated cases can reach two months or more; Joint functions may also be significantly affected, and therefore, if there is any suspicion of a dislocation, fracture, or even just a severe bruise of the joint, consultation with a trauma surgeon is strictly required.
What should be done?
After an injury occurs, an adult should immobilize a limb and seek professional help at an emergency room or the nearest traumatology department.
If signs of dislocation are observed in a child, it is necessary:
- Fix the limb and tape it to the body;
- Apply cold to the site of dislocation;
- If you complain of pain, give painkillers.
It is forbidden to carry out treatment on your own, as there is a serious risk of worsening the situation.
Treatment methods for patellar luxation
Conservative treatment of dislocation
If an injury occurs, the best option is to immediately consult a doctor; if this is not possible, the injured limb is immobilized, and cold is applied to the area of injury to reduce swelling, pain and reduce the likelihood of bleeding. Next, as soon as possible, you still need to contact a traumatologist or a trauma center. The doctor’s tactics should be aimed at anesthetizing the damaged area in order to painlessly and effectively realign the patella to avoid possible complications. Then I apply a plaster cast or a fixing bandage to the limb, the duration of which, as a rule, is at least 6 weeks. During this time, it is advisable for patients to undergo a course of physiotherapy using UHF. After removing the plaster, the patient needs to undergo repeated fluoroscopy and, if the result of treatment is positive, undergo a course of rehabilitation to maximize the restoration of joint mobility.
Patella dislocation surgery
Surgical intervention is resorted to only in case of a fracture of the patella, or if conservative treatment has not brought the desired result. The tactics of surgical intervention in each individual case are selected individually and depend on the severity of the pathological process. However, recovery usually requires a longer period, at least 9 weeks. The variety of surgical interventions is wide, but the most commonly used are:
- arthroscopy,
- plastic surgery of the medial ligament using open access,
- transposition of the distal attachment of the ligament.
If the intervention was carried out correctly and on time, then it is possible not only to suture and fix the joint capsule, but also to prevent the development of complications such as hemarthrosis, damage to joint cartilage. If a dislocation of the patella is combined with a rupture of the ligaments, then it is not possible to sew them together. In some cases, there is a need to restore joint mobility and ensure its function using artificial or donor tissue.
Perilunate dislocation
In this injury, the radius and lunate bones remain in place, but all the underlying bones (or several of them) are dislocated towards the back of the arm.
Sometimes the triquetrum or scaphoid bones are broken. Pain occurs in the affected area and a tumor develops. Normal limb functions are impaired.
Perilunate dislocation is reduced after anesthesia. Usually the fingers are stretched using a special apparatus.
After this, the dislocated bones are put back in place. Sometimes surgery is necessary.
Classification of patellar dislocations
- Congenital.
This pathological process is rare and basically implies, as a rule, underdevelopment of the connective tissue structures included in the structure of the knee joint. It rarely occurs separately and is combined with other types of dislocations. - Acquired or traumatic.
This pathology occurs due to direct traumatic effects. If more than a year does not pass between dislocations, then such dislocations are called habitual. Dislocations are also differentiated depending on how long ago they occurred: acute and chronic.
There is a classification based on the direction of bone displacement of the patella.
- Rotation
is when the patella changes its position relative to its axis. - Lateral -
usually appears due to a direct injury to the knee when the lower leg is extended. - Vertical is
an extremely rare type of dislocation, in which the patella in the horizontal plane enters the joint cavity.
According to the severity of the process
- Mild
- slight discomfort may be felt and a diagnosis can only be made after a thorough examination. - Medium degree
- leads to changes in gait and noticeable pain. - Severe degree
- entails the appearance of severe pain and often to the point of complete immobilization of the limb.
Lunate dislocation
A similar injury occurs when the hand is excessively extended in the opposite direction, for example, when a person falls while leaning on his hands.
In this case, the bone will move towards the palm, breaking the joint capsule and turning around its axis.
The victim tries to keep his fingers bent; their movements are painful. The diagnosis is made on the basis of radiographic examination.
Anesthesia is required during the reduction of a dislocation. The surgeon first pulls out the victim's fingers, and then presses on the bone and puts it in place.
A plaster cast is required. The position of the arm is changed after 3 weeks and the cast is applied again.
Rehabilitation after injury
To fully and quickly restore joint mobility, it is extremely important to undergo a high-quality course of rehabilitation treatment. The process itself must be carried out under the careful supervision of the attending physician. The rehabilitation course includes not only physical activity to develop the joint, but also massage and physiotherapeutic procedures. A set of physical exercises is selected for each patient individually, depending on his age, condition and severity of injury. The purpose of the prescribed loads is not only to restore the function of the knee joint, but also to achieve the previous amplitude and strength of movements. During the entire rehabilitation period, the patient uses a fixing bandage, because immediately after recovery it is impossible to put a full load on the joint, and they also do not allow it to fully bend and unbend, which can lead to re-displacement of the patella.