Polydactyly
Polydactyly, also known as duplicated fingers, refers to the redundancy of fingers other than normal fingers, finger bones, simple soft tissue components or metacarpal bones, etc. It is the most common congenital malformation of the hand in clinical practice, accounting for about 39,9% of congenital upper limb malformations (Liang Bingzhong, 1982), and its incidence is about 1 per 1,000; males are higher than females, with a male to female ratio of 3:2, more right-handed than left-handed, with a ratio of 2:1, and the incidence of both hands accounting for about The incidence of polydactyly of the thumb accounts for more than 90% of the total.
Symptoms and signs of polydactyly are obvious at a glance, and most of them can be diagnosed at the time of delivery, including polydactyly and mirror hand among the repetitive phenomena of the tissue. In polydactyly, multiple fingers can be single or multiple, or bilateral polydactyly; polydactyly is divided into three categories: radial polydactyly, central polydactyly, and ulnar polydactyly, with radial polydactyly being the most common, followed by ulnar polydactyly, and central polydactyly being rare. Polydactyly can occur at the end of the finger, proximal phalanges, connected to the normal phalanges or metacarpals, or at the side of the metacarpophalangeal and interphalangeal joints. Some polydactyly can be the result of repetitive development of a particular finger, with corresponding metacarpal polydactyly, forming a six-fingered hand or even a heavy hand deformity, but it is less common.
The shape and structure of the polydactyly can vary widely, from a dermatomal redundancy to a complete finger, and it can be difficult to distinguish a normal finger from a polydactyly, making the surgical decision difficult. The angle of growth of the polydactyly also varies, with some polydactyly being at right angles to the radial or ulnar margins of the hand. The polydactyly may exist alone or in conjunction with other deformities, such as compound thumb deformity; some have 3 or 4 extra fingers, forming a “mirror hand” deformity. The ulnar polydactyly can be accompanied by various other deformities, such as syndactyly, trigeminal thumb, spinal deformity, nail dysplasia, etc. Central polydactyly is often accompanied by syndactyly, which is more common bilaterally and named as polydactyly, and central polydactyly is often a kind of split hand deformity. X-ray examination should be performed for polydactyly to clarify its osteoarthritic condition and provide a basis for surgery.
Classification: Polydactyly is mainly divided into three types according to its occurrence and anatomical site: thumb polydactyly of pre-axial type (also called radial polydactyly, pre-axial polydactyly, compound thumb deformity), central polydactyly and pinky polydactyly of post-axial type (also called ulnar polydactyly, post-axial polydactyly). The classification of thumb polydactyly is based on Wassel’s classification of pathologic anatomic shape abnormalities, which is divided into seven types, i.e., three types of terminal phalanges, proximal phalanges and metacarpals, and each deformity is divided into two types of bifurcation with bony connection and compound thumb with articular connection according to the degree of separation of the duplicated fingers, plus seven types of 3-jointed thumb (Table 1), of which type IV is the most common, accounting for 47%, type Ⅶ for 23%, and type Ⅱ for 23%. Type VII accounts for 23%, and type II accounts for 15%. This classification method is concise and consistent with pathology and anatomy. The classification of polydactyly in the little finger is mostly based on the Stelling-Twrek classification, which divides it into three types: type I for redundant fingers, type II for the presence of partial bony structures, and type III for complete polydactyly including the metacarpals. Central polydactyly is rare and is a repetitive deformity of the index finger, middle finger and ring finger. The above three fingers are rarely present as single-finger compound deformities, but always contain complex syndactyly, and the most common polydactyly is hidden in the syndactyly of the middle finger and ring finger.
Clinically, according to the different tissue components contained in the superfluous fingers, they can be divided into three categories.
1, soft tissue polydactyly: polydactyly with only soft tissue redundancy, without bone, tendon and other tissues.
2, simple polydactyly: the polydactyly contains finger bones, tendons and vascular nerve bundles connected to the normal finger, which is a functionally defective finger.
3, compound polydactyly: polydactyly is a true duplication, containing not only finger bones, tendons, etc., but also including metacarpal twins.
Treatment with medication.
1, surgical treatment of polydactyly
It is important not only to have obvious cosmetic results, but also to reconstruct the function of the hand. Surgical excision of polydactyly is not difficult, but it requires a comprehensive consideration based on the shape, location, structure of the polydactyly and the relationship with the normal fingers, combined with X-ray examination, to decide the site and manner of polydactyly excision. For simple polydactyly, polydactyly excision and local skin reconstruction are performed; for compound polydactyly, in addition to polydactyly excision, total or partial excision of the redundant metacarpal bone is also required. The amount of metacarpal bone removal is determined by the morphology and functional reconstruction requirements of the affected hand. In addition to the removal of polydactyly, sometimes it is necessary to perform joint and bone deformity correction, joint ligament repair and skin reshaping, etc.
2.Surgery timing
For redundant fingers that are connected to normal fingers only by a narrow cuticle, simple excision is sufficient and can be performed after birth; for simple polydactyly, especially ulnar polydactyly, surgery is better 3-6 months after birth; for complex polydactyly with severe deformity and tissue defects, microsurgical techniques can be used to perform polydactyly excision after the age of 1 year and perform surgical reconstruction such as tissue transplantation or transposition, and regular review until the developmental arrest period. Metacarpal and phalangeal osteotomy orthopedics should be performed after 1 year of age; functional reconstruction of the metacarpal should be done after 3 years of age, and transposition of the long palmar tendon is more appropriate.
3.Anatomy of thumb polydactyly
The treatment is often more complicated than expected, and simple resection often brings deformity, joint instability, and dysfunction, so the surgical plan should be decided according to different situations. In principle, the thumb with a more normal appearance and better function should be preserved. If there is a major neurovascular bundle in the multifidus to be removed, it should be carefully separated and preserved without damage; if there is a major tendon or intrinsic muscle stop, it should also be relocated to the corresponding position of the preserved thumb. In the case of multiple finger resection located within the metacarpophalangeal or interphalangeal joint capsule, the joint capsule and ligamentous tissue of the multiple fingers should be preserved and used to repair the thumb capsule and maintain joint stability. When the preserved thumb is too oblique, joint fusion or osteotomy orthopedics should be performed after the basic cessation of epiphyseal development.
4.Bifurcation deformity of the end thumb
In order to improve the appearance of the thumb, the bones, skin and nails in the middle of the thumb can be removed in a wedge shape, and the two sides of the thumb can be directly sutured together to form a thumb. If the end joint thumb is small and on one side, the defect can be covered with a palmar flap and sutured inward to reconstruct the nail groove after excision.
5.Multifidus thumb deformity
It can be corrected by finger thumbing surgery. Wood (1977) performed a central osteotomy of the triangular phalanges followed by a wedge-shaped bone graft to correct the deformity. Reverse wedge osteotomy implantation can also be used, that is, the triangular finger bone is osteotomized in a wedge shape on the long side of its interface and transplanted to the short side of the interface to correct the angular deformity of the finger.
6.Polypectomy of the ulnar side of the little finger
Generally, it does not involve the repair of joint capsule and tendon, but should be removed together when there are multiple metacarpals.
7.Central polydactyly excision
As it is often accompanied by syndactyly, vascular and nerve variants occur repeatedly, the blood supply and innervation of the surviving finger should be avoided to prevent necrosis of the surviving finger when excision is performed.
8.Proximal phalangeal type polydactyly
The focus of surgery is on orthopedic and functional reconstruction. The joint capsule and lateral collateral ligaments attached to the polydactyly should be preserved, and after removal of the polydactyly, the intrinsic muscles of the hand should be firmly sutured to the base of the proximal phalanx of the preserved finger, and the joint capsule and ligaments should be repaired to maintain the stability of the finger joint. When multiple fingers are removed, the extensor and flexor tendons can be preserved to enhance the extension and flexion of the preserved finger or used to reconstruct the lateral collateral ligaments. In case of congenital defect of the extensor and flexor tendons of the preserved finger, the extensor tendon of the index finger and the superficial flexor tendon of the ring finger can be transposed at the same time as the polydactyly is resected to reconstruct the function of the preserved finger.
9.Multifinger resection
Attention should be paid to complete resection to avoid leaving deformities that may hinder the appearance, and to avoid damaging the epiphysis and affecting the development because the surgery is mostly performed before school age.
10.Pay attention to long-term follow-up
The early results of polydactyly are satisfactory, but as the child develops, a few secondary deformities may appear. Therefore, long-term regular follow-up should be carried out after surgery until the developmental period stops.
Dietary care.
1.More light food and pay attention to the regular diet.
2.Eat reasonably according to the doctor’s advice.
3.The disease does not have much contraindication to diet, and a reasonable diet is sufficient.
Preventive care
Enhance health care and nutrition during pregnancy, avoid respiratory infections, gastrointestinal infections, rubella, measles, chicken pox, mumps and other viral infections during pregnancy, and avoid exposure to radiation, drugs and other possible embryonic teratogenic factors.
Pathogenesis
The etiology of the disease is not known, but some cases are genetic, and there is intergenerational inheritance.