Thumb three

Introduction Polydactyly is the most common hand congenital malformation, which occurs mostly on the temporal side of the hand and sometimes incorporates other deformities. Clinically, it can be divided into three types: 1 excess finger has only soft tissue and no bone. 2 There are some phalanx and part of the tendon in the excess finger, which is a finger with functional defects. 3 has a complete palm and phalanx, and the function is also complete, it is difficult to distinguish which finger is multi-finger. Wassel divided the temporal side into seven types: type I, distal phalanx bifurcation; type II, distal phalanx completely repeated; type III, distal phalanx repeat; type IV, proximal phalanx completely repeated; V-type, first A metacarpal bifurcation and a proximal phalanx base of the repeated fingers form a joint respectively; a type VI, a metacarpal repeat, and a complete thumb repeat; a type VII, a normal thumb is a three-section phalanx or a partial three-section phalanx finger.

Cause

(1) Causes of the disease

The cause is unknown, some cases are genetic factors, and there are genetic hereditary phenomena. May be caused by multiple factors. Damage to the early stage of limb blast embryo differentiation is an important cause of repeated malformations.

(two) pathogenesis

The influence of environmental factors on the development of embryos, such as certain drugs, viral infections, trauma, stimulation of radioactive materials, etc., especially in modern industry, can become teratogenic factors, and the early stage of embryonic bud differentiation is damaged. It is an important cause of multi-finger malformation. The thumb-to-finger malformation is due to the abnormal development of the ectoderm vertebral ridge, the proximal apical extension of the thumb and the slow withdrawal.

an examination

Related inspection

Thumb tip relative test

After birth, there is an appearance deformity. If there is no difficulty in diagnosis, routine X-ray examination should be taken before surgery to understand the development of the phalanx and metacarpal bones, and to master the degree of malformation and classification to decide to adopt the correct surgical procedure.

The classification of the thumb multi-finger is currently based on the Wassel classification based on the pathological anatomical shape abnormality, which is divided into seven types, namely, the last type finger type, the proximal phalanx type and the metacarpal type. Each type of deformity is based on repeated The degree of separation is divided into two types: a bifurcation type with a bone connection and a double finger type with an articulation type, and a total of 7 types of a thumb type. Among them, type IV is the most, accounting for 47%, type VII is 23%, and type II is 15%. This classification is concise and consistent with pathology and anatomy.

Type I: distal phalanx bifurcation, common osteophytes and interphalangeal joints, most of which have two separate nails, a few have a single nail, and the end of the thumb is flat and wide.

Type II: The distal phalanx is completely repetitive, each with its own independent epiphysis, which is associated with the proximal phalanx.

Type III: distal phalanx repeat, proximal phalanx bifurcation, respectively forming a joint with the repetitive distal phalanx, and a normal joint between the proximal phalanx and the metacarpal head.

Type IV: The proximal phalanx is completely repetitive, each with an independent epiphysis, associated with a slightly widened metacarpal head.

Type V: The first metacarpal bifurcation and the proximal phalanx base of the repeated fingers form joints, respectively.

Type VI: Repeated metacarpal bones, complete thumb repetition, one of which can be stunted.

Type VII: The normal thumb is a three-pointed phalanx or a part of a three-section phalanx finger. The three-pointed phalanx is overdeveloped and repeats thumb dysplasia.

Type I is a twin, and type II is a partial bone structure. Type III is a complete multi-finger including the metacarpal bone. The central multi-finger is rare. It is a repeated deformity of the index finger, middle finger and ring finger. The above three fingers are rarely single-finger and multiple-finger malformations, but always contain complex and finger deformities. The most common multi-finger is hidden in the middle finger and ring. Refers to the deformity.

Differential diagnosis

1. Also refers to: the lighter only has incomplete aponeurosis between the two fingers; the heavier skin merges with the subcutaneous soft tissue, and the nails are separated. In severe cases, the 2nd-5 fingers are connected to each other, and the phalanx is incomplete and multiple joint deformities. The phalanx of the finger is fused with the nail and the rest is normal. It also refers to the majority occurring between the middle finger and the ring finger, often bilateral. It can also be complicated by phalangeal fusion deformity, short finger, multi-finger, toe or foot deformity. Multiple fingers and fingers affect the function of the hand.

2. Multiple fingers: often have both fingers, short fingers and other deformities. Multi-finger is most common with the thumb, followed by the little finger, sometimes bilateral.

There are 3 types of malformations:

1 Abnormal soft tissue block, no adhesion to bones.

2 Repeat the finger, including the phalanx, joints, tendons and other parts, the proximal phalanx and the metacarpal head or the bifurcated metacarpal joints.

3 completely extra fingers, including a complete metacarpal and polyphalangeal connection.

3. Missing fingers and hand cracks: divided into two types: central type and edge type. The central type of missing finger is the lack of index finger, middle finger and ring finger. Sometimes the corresponding metacarpal bone is also absent. The palm of the hand is split, and the hand is divided into two parts, like a lobster claw or a hand crack. Some hand cracks only lack the middle finger and the third. Metacarpal. The appearance of the hand is ugly, but there are some functions.

4. Floating thumb: Congenital absence of the first metacarpal, poor thumb development, lack of intermuscular muscles, thumb flexor and extensor muscles still have some active functions.

5. Giant finger: refers to a rare deformity of one finger, several fingers or a full hand, which may be caused by abnormal development or caused by neurofibromatosis. Both finger bone and soft tissue length and width increase. Neurofibromatosis itself is often insignificant, while hypertrophic parts are prominent.

6. Short finger: One or several fingers become shorter due to abnormal embryonic development, which may be accompanied by a decrease in the number of phalanxes and a shortening of the metacarpal bone. Malformations often occur simultaneously with or with multiple fingers. The shape and function of the fingers are generally normal.

7. Thumb flexor tendon stenosis Tenosynovitis, also known as "trigger thumb": is a common congenital malformation in children, often found in 6 months to 2 years old. This disease is the narrowing of the flexor cartilage lesion of the tendon sheath at the distal end of the metacarpophalangeal joint. After the tendon sheath is cut, the tendon has a notch or a groove, and the tendon of the proximal side of the incision is thickened or formed. Nodular. The interphalangeal joint of the thumb is fixed at the flexion position and cannot be actively stretched, but can be flexed to a certain extent. Sometimes the thumb can be forced to straighten temporarily, but it quickly returns to the flexion position, causing pain or bounce of the thumb when passively stretching. The volar side of the metacarpophalangeal joint sometimes touches thickened muscle nodules, sometimes with tenderness.

8. Thumb flexion, adduction malformation and finger flexion deformity: all fingers are flexed and contracted at the distal end, accompanied by thumb adduction deformity. The disease is rare and hereditary. The typical posture is the adduction of the thumb, and the metacarpophalangeal joint is obviously flexed. The rest of the fingers near the interphalangeal joint flexion deformity. The skin on the palm side is curled up. The thumb short extensor muscle is underdeveloped or absent. The remaining fingers have incomplete or absent muscles. Finger deformity can be alleviated when the wrist is flexed, and the developmental disorder of the superficial flexor is the main cause of deformity.

9. Finger valgus deformity: rare, mostly occurs in the little finger, with obvious hereditary. The little finger flexed slightly and leaned toward the ring finger.

10. phalangeal fusion malformation: ligament joint developmental disorders, causing phalangeal joint fusion. Most occur in the distal phalanx joints. Often hereditary.

11. Three-finger phalanx deformity of the thumb: The thumb develops into three phalanx bones, and the big fish muscles are poorly developed. The gap between the first and second metacarpals is narrowed and the thumb function is normal.

12. Little finger malnutrition: rare. The lesions are often bilateral and more common in women. Found around 10 years old. The little finger is shorter and the fingertips are bent outwards without pain, tenderness or other symptoms. After birth, there is an appearance deformity. If there is no difficulty in diagnosis, routine X-ray examination should be taken before surgery to understand the development of the phalanx and metacarpal bones, and to master the degree of malformation and classification to decide to adopt the correct surgical procedure.

The material in this site is intended to be of general informational use and is not intended to constitute medical advice, probable diagnosis, or recommended treatments.