Metacarpophalangeal Joint Dislocation

　　The dislocation of the metacarpophalangeal joint is often caused by excessive extension force. This disease is mainly caused by indirect forces leading to finger sprains and punctures. It occurs when the fingers are excessively extended, and the thumb and index finger are most affected. The dorsal half-dislocation of the metacarpophalangeal joint of the thumb is usually caused by excessive extension of the thumb metacarpal due to excessive extension force, often leading to tears of the proximal palmar plate. The dorsal half-dislocation of the metacarpophalangeal joint of the thumb is also known as a simple dorsal dislocation, which is between the surfaces of the metacarpal and phalanges, but most of the joint connections still exist. Depending on the degree, it can be divided into simple and complex types of dislocation.

　　Due to the difficulty of reduction in metacarpophalangeal joint dislocation, malalignment may occur after reduction. For patients with closed injuries, early treatment is relatively easy, but if it exceeds the optimal treatment time, it is inevitable that joint stiffness, pain, and subsequent functional disorders may occur, even leading to disability.

　　The dislocation of the metacarpophalangeal joint often occurs in the thumb and index finger, after dislocation, the phalanges move to the dorsal side, the metacarpal head protrudes to the palmar side, forming an excessive extension deformity. The index finger also has a ulnar deviation and a semi-flexed interphalangeal joint deformity. The symptoms include local swelling, pain, and dysfunction.
　　Finger sprains, strong finger extension, and other conditions can cause dislocation of the metacarpophalangeal joint, which is more common in the thumb and index finger. After dislocation, the phalanges move to the dorsal side, the metacarpal head protrudes to the palmar side, forming an excessive extension deformity. The index finger often deviates towards the ulnar side after dislocation, with the interphalangeal joint semi-flexed. Manual reduction of joint dislocation often fails, due to the fact that when the thumb is dislocated, the metacarpal head pierces the palmar joint capsule, the neck is caught between the longitudinal tears of the joint capsule, the metacarpal plate is embedded between the two joint surfaces, and sometimes the sesamoid bone or the long flexor muscle tendon is also embedded, making reduction difficult. When the index finger is dislocated, the metacarpal head pierces the joint capsule from the proximal end of the metacarpal plate, the metacarpal plate is embedded between the two joint surfaces, and the metacarpal neck is caught between the flexor tendons and the lumbrical muscles, making reduction difficult.

　　The dislocation of the metacarpophalangeal joint is mainly caused by indirect external force, therefore, the most important prevention of this disease is to prevent finger sprains, punctures, and other injuries. For patients who have been injured, they should seek medical attention promptly in order to receive timely treatment in the early stage, preventing more severe damage. Patients should also pay attention to functional exercises under the guidance of the doctor to help restore hand function as soon as possible.

　　There are no related laboratory tests for metacarpophalangeal joint dislocation, and the main method of examination for this disease is X-ray examination. Since the manifestations of dislocation in different parts are not the same, the X-ray examination of the metacarpophalangeal joint of the thumb is used as an example to explain its X-ray examination findings. The X-ray manifestations of the dorsal semi-dislocation of the metacarpophalangeal joint are as follows:

　　1. The interphalangeal joint of the thumb is in a flexed position.

　　2. Dorsiflexion of the proximal phalanx of the thumb.

　　The metacarpal head is round, which can be dorsiflexed 50° under physiological conditions, while the flat metacarpal head can hardly be overextended, and slight overextension is abnormal. Therefore, although the dorsiflexion of the proximal phalanx of the thumb is the most fundamental manifestation of semi-dislocation, all other signs are caused by it. However, due to the individual differences in the shape of the metacarpal head, the variation in the range of motion of the metacarpophalangeal joint is large, and it is necessary to be cautious in judging whether it is dorsiflexion. The X-ray manifestation of the dorsal semi-dislocation of the metacarpophalangeal joint itself is very slight, so the shape of the metacarpal head and the specific angle of dorsiflexion are also of great reference value in judging whether the phalanx is overextended or not.

　　3. Abnormal position of the sesamoid bone of the metacarpophalangeal joint.

　　4. The space between the metacarpophalangeal joint of the thumb is uneven, and the abnormal joint space is caused by the excessive dorsiflexion of the proximal phalanx of the thumb, causing the soft tissue to be inserted into the palmar side.

　　Patients with metacarpophalangeal joint dislocation should pay attention to a light diet and balanced diet. Patients should enhance nutrition and eat more protein-rich foods such as fish, eggs, and soy products, and appropriately increase calcium. Drink more water, eat more vegetables and fruits such as green vegetables, celery, and bananas. Patients should also pay attention to avoiding spicy foods such as chili and mustard. Habits such as smoking and drinking should be戒除.

　　The metacarpophalangeal joint, the palm and the back, although externally unified and not divided, are connected by the bones inside, which are the joints of each finger. Dislocation and depression require manual support, and prominence requires hand pressing in, all of which should be slightly pulled, and should not be forced. In traditional Chinese medicine, internal medication for the disease is based on the three phases of fracture syndrome differentiation, and external application of traditional Chinese medicine fumigation and washing in the later stage.