Congenital clasped thumb describes an anomaly which is characterized by a fixed thumb into the palm at the

metacarpophalangeal joint The metacarpophalangeal joints (MCP) are situated between the metacarpal bones and the proximal phalanges of the fingers. These joints are of the condyloid kind, formed by the reception of the rounded heads of the metacarpal bones into shallow cav ...

in one or both hands.Miura T: Flexion deformities of the thumb. In Buck-Gramcko D (ed): Congenital Malformations of the Hand and Forearm. London, Churchill Livingstone, 1998, pp 425-429. The incidence and genetic background are unknown. A study of Weckesser et al. showed that boys are twice as often affected with congenital clasped thumb compared to girls. The anomaly is in most cases bilateral (present in both hands). A congenital clasped thumb can be an isolated anomaly, but can also be attributed to several syndromes.

Causes

The thumb contains five groups of muscle and/or tendons: # Extensor tendons (to stretch the thumb) # Flexor muscles/tendons (to bend the thumb) # Abductor muscles/tendons (to move the thumb outwards) #

Adductor muscle A adductor muscle is any muscle that causes adduction. It may refer to: Humans * Adductor muscles of the hip, the most common reference in humans, but may also refer to ** Adductor brevis muscle, a muscle in the thigh situated immediately behind ...

(to move the thumb inwards) # Opposing muscles (to move the thumb opposite the small finger) In order for the thumb to maintain a normal position, a strict balance between these groups is required. Weak or absent extensors and/or abductors (the

extensor pollicis brevis In human anatomy, the extensor pollicis brevis is a skeletal muscle on the dorsal side of the forearm. It lies on the medial side of, and is closely connected with, the abductor pollicis longus. The extensor pollicis brevis (EPB) belongs to the ...

tendon, the

extensor pollicis longus In human anatomy, the extensor pollicis longus muscle (EPL) is a skeletal muscle located dorsally on the forearm. It is much larger than the extensor pollicis brevis, the origin of which it partly covers and acts to stretch the thumb together with ...

tendon or, rarely, the

abductor pollicis longus In human anatomy, the abductor pollicis longus (APL) is one of the extrinsic muscles of the hand. Its major function is to abduct the thumb at the wrist. Its tendon forms the anterior border of the anatomical snuffbox. Structure The abductor p ...

tendon), can cause a disbalance, leading to an abnormal position of the thumb: congenital clasped thumb. There is also the possibility that two tendons are affected simultaneously. The following tendon deviations can induce congenital clasped thumb: * The flexor tendons are too short (the thumb is drawn into the palm) * The abductor tendons are hypoplastic or absent * The extensor tendons are hypoplastic or absent Furthermore, a tight thumb web space (the area between thumb and index finger) can contribute to congenital clasped thumb. The thumb cannot be properly abducted (moved outwards), if the web space is too tight. To summarize, the causes of congenital clasped thumbs may vary between patients and can sometimes be a combination of the preceding components. Treatment should be tailored to all occurring components in order to achieve good results.

Diagnosis

Diagnosing the congenital clasped thumb is difficult in the first three to four months of life, as it is normal when the thumb is clutched into the palm in these first months. Diagnoses that cause the same flexion or adduction abnormalities of the thumb are: * Congenital clasped thumb * Congenital Trigger thumb (flexion of the interphalangeal joint) -

Trigger finger Trigger finger, also known as stenosing tenosynovitis, is a disorder characterized by catching or locking of the involved finger in full or near full flexion, typically with force. There may be tenderness in the palm of the hand near the last s ...

Spasticity Spasticity () is a feature of altered skeletal muscle performance with a combination of paralysis, increased tendon reflex activity, and hypertonia. It is also colloquially referred to as an unusual "tightness", stiffness, or "pull" of muscles. ...

: overstimulation of muscles Syndrome associated flexion-adduction of the thumb: *

Freeman–Sheldon syndrome Freeman–Sheldon syndrome (FSS) is a very rare form of multiple congenital contracture (MCC) syndromes ( arthrogryposes) and is the most severe form of distal arthrogryposis (DA). It was originally described by Ernest Arthur Freeman and Joseph H ...

(a congenital, heritable affection of the face, the hands, the feet and some joints) * Distal

arthrogryposis Arthrogryposis (AMC) describes congenital joint contracture in two or more areas of the body. It derives its name from Greek, literally meaning "curving of joints" (', "joint"; ', late Latin form of late Greek ', "hooking"). Children born with one ...

MASA syndrome MASA syndrome is a rare X-linked recessive neurological disorder on the L1 disorder spectrum belonging in the group of hereditary spastic paraplegias a paraplegia known to increase stiffness spasticity in the lower limbs. This syndrome also has t ...

* X-linked hydrocephalus *

Adducted thumb syndrome Adducted thumb syndrome recessive form is a rare disease affecting multiple systems causing malformations of the palate, thumbs, and upper limbs. The name Christian syndrome derives from Joe. C. Christian, the first person to describe the conditio ...

Waardenburg syndrome Waardenburg syndrome is a group of rare genetic conditions characterised by at least some degree of congenital hearing loss and pigmentation deficiencies, which can include bright blue eyes (or Heterochromia iridum, one blue eye and one brown ey ...

* Whistling face syndrome (

) * Digitotalar dysmorphism * Multiple pterygium syndrome

Classification

There are a few different classifications conceived to categorize the spectrum of variety of congenital clasped thumb. In literature, X classifications have been described for clasped thumb. The two most relevant of the existing classifications, to our opinion, are the classifications of McCarrol and Tjuyuguchi et al. The most global format is the classification of McCarrol, which divides the congenital clasped thumbs into two groups. Group I includes the supple clasped thumb, when the thumb is only passively correctable. While complex clasped thumbs, thumbs which cannot be moved neither passively or actively, belong to group II. Tjuyuguchi et al. designed a classification existing of three groups: * Group I: The supple clasped thumb, where the thumb is passively abductable and extendable against the resistance of thumb flexors, without other digital anomalies. * Group II: The clasped thumb with hand contractures, where the thumb is not passively extendable and abductable, with or without other digital anomalies. * Group III: The clasped thumb which is associated with

Treatment

Treatment of congenital clasped thumb includes two types of therapy: conservative and surgical.

Conservative treatment

Treatment of all categories of congenital clasped thumbs should start with either serial plaster casting or wearing a static or dynamic splint for a period of six months, while massaging the hand. Extension by splinting shows reduction of the flexion contracture. To gain optimal results, it is important to start this treatment before the age of six months. The result of this therapy is better in less severe deformities. In most uncomplicated cases, a satisfactory result can be gained when splint therapy starts before the age of six months. Splinting should be tried for at least three months and possibly for as long as six months or longer. If the result of splint therapy stagnates, surgery treatment is indicated.

Surgical treatment

Surgical treatment should be considered in patients who have not been treated at younger age or when conservative therapy fails. Surgery is recommended during the age of three to five years. ''Techniques'' * Release the thumb web space: it is possible to widen and deepen the area between the thumb and the index finger when it is too tight. To achieve this, a transposition flap or four-flap or five-flap Z-plasty can be used. ** Transposition

flap Flap may refer to: Arts, entertainment, and media * ''Flap'' (film), a 1970 American film * Flap, a boss character in the arcade game ''Gaiapolis'' * Flap, a minor character in the film '' Little Nemo: Adventures in Slumberland'' Biology and he ...

:Ronald Friedman MD et al. The dorsal transposition flap for congenital contractures of the first web space: A 20-year experience. The Journal of Hand Surgery, Volum 22, Issue 4, July 1997. skin flaps of the index finger and/or the thumb are moved to the web space. ** Four-flap or five-flap

Z-plasty Z-plasty is a versatile plastic surgery technique that is used to improve the functional and cosmetic appearance of scars. It can elongate a contracted scar or rotate the scar tension line. The middle line of the Z-shaped incision (the central ele ...

: the web space is widened and deepened with skin of the web space itself. : *

Tendon transfer A tendon transfer is a surgical process in which the insertion of a tendon is moved, but the origin remains in the same location. Tendon transfer involves redistribution of muscle power, not recreation. Tendons are transferred at the distal atta ...

: a technique usually considered for young children, in which tendons of index finger or little finger are used to make an adequate new extensor tendon for the thumb. ''Other procedures'' *

Arthrodesis Arthrodesis, also known as artificial ankylosis or syndesis, is the artificial induction of joint ossification between two bones by surgery. This is done to relieve intractable pain in a joint which cannot be managed by pain medication, splin ...

: fixing the metacarpophalangeal joint of the thumb in a more extension position.

References

{{Reflist Congenital disorders of musculoskeletal system