Outline  
The dislocation of metacarpophalangeal joint is mostly toward the palm. The strong dorsoextension of the fingers results in rupture of the articular capsule on palmar side, the metacarpal end passes through the split of rupture and slips into the subcutaneous region on palmar side, and the base of phalangeal bone displaces to the dorsal side of the metacarpal end. If the split is smaller, the metacarpal end is often locked inside the capsule, showing a button-form, which makes the reduction difficult. The dislocation often occurs in the first and second metacarpophalangeal joints.

Major points for diagnosis  
1. There is a typical traumatic history.
 
2. There are swelling and pain in the metacarpophalangeal joints that are incapable of motion.
 
3. There is marked deformity in the metacarpophalangeal joints with swelling on palmar surface. The displaced metacarpal end can be palpated at the transverse palmar crease subcutaneously. The finger becomes shorter. The metacarpophalangeal joint is elastically fixed in hyperextension position. The interphalangeal joint is in flexion position.
 
4. X-ray film can show the displaced metacarpal end.

Treatment  
Reduction:   
Under a local anesthesia, an assistant fixes the sick forearm on the part superior to the wrist. The operator holds up with his thumb and index finger of one hand the displaced finger in a hyperextension position, performing continuous traction along with the direction of deformity. Moreover, he holds up the sick carpal joint with the other hand and, presses the base of sick finger and pushes it toward the distal end with his thumb, making the base go against the metacarpal end. Then slightly flexes the sick finger to gain reduction.

Fixation:   
Put a bent metal spatula or a bandage roll on the palmar side of the metacarpopbalangeal joint, and then wrap it up with bandage with the joint fixed in a hemiflextion position for three weeks.

Functional exercise:    
At the early stage, all phalangeal joints except the sick one should practice functional exercises. After the removal of fixation, the active flexion and extension of metacarpophalangeal joints should be done, the range of movement should be from small to large.

Herbal therapy  
Internal treatment based on syndrome different iat ion
 
1. In the early stage
Main symptoms and signs:
Swelling and pain in the sick finger, which is limited in movement or with ecchymoses.
 
Therapeutic methods:
Promoting blood flow to remove the stasis, relieving swelling to stop pain.
 
Recipe and herbs:
Modified Fuyuan Huoxue Decoction. The herbs are the same as those in the treatment of clavicular fracture in the early stage.
 
2. In the late stage
Main symptoms and signs:
Rigidity of the metacarpophalangeal joint that is limited in movement.
 
Therapeutic methods:
Relaxing tendons and activating collaterals, freeing joint movement.

Recipe and herbs:
Modified Shujin Decoction. The herbs are the same as those in the treatment of dislocation of shoulder joint in the late stage.