Metacarpophalangeal dislocation

Introduction to metacarpophalangeal joint dislocation The metacarpophalangeal joint is a biaxial joint consisting of the proximal phalanx base, the metacarpal head, the metacarpal sac, the collateral ligament, the accessory collateral ligament, and the joint capsule. It has flexion-extension, adduction-abduction, and a certain amount of circumferential convolution. Exercise, in which the flexion-extension movement is the largest. Dislocation of the metacarpophalangeal joint is more common in the thumb and index finger, which is rare in other fingers. Most of them are dislocated on the volar side. The dislocation of the dorsal side is rare. Usually, the finger is overextended. It is subjected to longitudinal violence, causing the volar joint capsule of the metacarpophalangeal joint to rupture and the palmar fiberboard to tear from the membrane. The metacarpal bone passes through the ruptured joint capsule and is removed from the side of the flexor tendon to the subcutaneous side of the hand, and the base of the proximal phalanx is moved to the dorsal side of the metacarpal head. basic knowledge The proportion of illness: the incidence rate of hand trauma patients is about 10% Susceptible people: no specific population Mode of infection: non-infectious Complications: joint sprains

The cause of metacarpophalangeal joint dislocation

(1) Causes of the disease

It is often caused by excessive violence.

(two) pathogenesis

The disease is mainly caused by indirect strength caused by finger sprains, punctures, and extreme finger extensions. The thumb and index finger are the most, and the dorsal subluxation of the thumb and phalanx is usually caused by excessive external force. Stretching, often leading to proximal palmar tear, the dorsal subluxation of the metacarpophalangeal joint is also called simple dorsal dislocation, that is, between the metacarpophalangeal surface, but most of the joints still exist, according to the degree, can be divided into simple, complex Two types of dislocation.

Metacarpophalangeal joint dislocation prevention

The disease is mainly caused by indirect external force. Therefore, the main prevention of this disease is to prevent finger sprains, punctures, etc. For patients who have been injured, they should seek medical treatment in time so as to get timely treatment in the early stage, so as not to cause more serious problems. The damage should also be paid attention to under the guidance of a doctor to perform functional exercises to restore the hand function as soon as possible.

Metacarpophalangeal joint dislocation Complications, joint sprains

Because the disease is difficult to reset, deformity can occur after the reduction. For some patients with closed injury, early treatment is easier, but if the optimal treatment time is exceeded, it will inevitably avoid joint stiffness, pain, and then concurrent dysfunction. Even disabling.

Metacarpophalangeal joint dislocation symptoms common symptoms joint pain motor dysfunction sprain joint deformity joint swelling

Sprained fingers, strong dorsiflexion of the fingers, etc. can cause dislocation of the metacarpophalangeal joint, more common in the thumb and index finger. After dislocation, the phalanx is displaced to the dorsal side, and the metacarpal head protrudes to the volar side to form a joint overextension.

After the dislocation, the index is often biased to the ulnar side. The interphalangeal joint is half-buckled. The joint dislocation often fails. Because of the dislocation of the thumb, the metacarpal head wears the volar joint capsule, and the neck is caught between the longitudinally torn joint capsules. The palm plate is embedded between the two articular surfaces, and sometimes the sesamoid or the flexor hallucis longus tendon is embedded therein, which makes the resetting difficult. When the finger is dislocated, the metacarpal head penetrates the joint capsule from the proximal end of the palm plate, and the palm plate is embedded between the joint surfaces. The sides of the metacarpal neck are sandwiched between the flexor tendon and the sacral muscles, making it difficult to reset.

Examination of metacarpophalangeal joint dislocation

There is no relevant laboratory examination. The main method of examination for this disease is X-ray examination. Because the performance of dislocation of each part is not the same, the performance of X-ray examination is illustrated by the thumb and knuckle joint, and the dorsal metacarpophalangeal joint The subluxation X-ray performance is as follows:

(1) The joint between the thumb is flexed.

(2) Thumb proximal phalanx extension.

The metacarpal head is round and can stretch 50° under physiological conditions; while the metacarpal head is flat, it can hardly stretch, and slight overextension is abnormal, so although the proximal phalanx of the thumb is the most fundamental manifestation of subluxation, The rest of the signs are due to their occurrence, but because the shape of the metacarpal head varies from person to person, the amplitude of the metacarpophalangeal joints varies greatly. It is necessary to be cautious in judging the extension of the metacarpophalangeal joint. The X-ray of the dorsal subluxation of the metacarpophalangeal joint is very slight. Therefore, judging whether the phalanx is excessively stretched or not, the shape of the metacarpal head has the same important reference value as the specific angle of extension.

(3) The position of the sesamoid bone of the thumb and knuckle joint is abnormal.

(4) The gap between the metacarpophalangeal and phalangeal joints is uneven. The abnormal joint space is caused by the soft tissue embedding of the palmar side of the proximal phalanx of the thumb.

Diagnosis and differentiation of metacarpophalangeal joint dislocation

The disease occurs more in the thumb, indicating the finger, after the dislocation, the phalanx is displaced to the dorsal side, the metacarpal head is protruding to the volar side, forming a joint over-extension deformity, indicating that there is still a ulnar deviation and a semi-buckling deformity of the interphalangeal joint, which is characterized by local swelling. Pain, dysfunction, and diagnosis rely mainly on the results of X-ray examination.

Clinically, it needs to be differentiated from metacarpal and phalangeal fractures. X-ray examination can be used for identification.

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