Triphalangeal thumb
Encyclopedia
A triphalangeal thumb is a congenital malformation where the thumb
has three phalanges instead of two. Besides the three phalanges, there can also be other malformations. The extra phalanx can vary from a very small phalanx to a full extra phalanx in a more finger-like thumb. It was first described by Columbi in 1559. The true incidence is unknown, but is estimated at 1:25,000 live births. In about two-thirds of the patients with triphalangeal thumbs, there is a hereditary component.
), thumb strength can be diminished. In the case of a five fingered-hand it has a finger-like appearance, with the position in the plane of the four fingers, thenar muscle deficiency, and additional length. There is often a combination with radial polydactyly
.
Syndromes include:
Malformations include:
The classification according to Wood describes the shape of the extra phalanx: delta (Fig. 4), rectangular or full phalanx (Table 1). With the classification made by Buck-Gramcko a surgical treatment can be chosen (Table 1). Buck-Gramcko differentiates between six different shapes of the extra phalanx and associated malformations.
Table 1: Classifications of Wood and Buck-Gramcko
{| class="wikitable"
|-
! Classification according to Wood by shape of the extra phalanx !! Shape!! Classification according to Buck-Gramcko by shape/size of extra phalanx and associated malformations !! Shape
|-
| I|| Delta|| I|| Rudimentary triphalangism
|-
| || || II|| Short triangular middle phalanx (brachymesophalangeal)
|-
| II|| Rectangular|| III|| Trapezoidal middle phalanx (intermediate)
|-
| || || IV|| Long rectangular middle phalanx (dolichophalangeal)
|-
| III|| Full|| V|| Hypoplastic triphalangeal thumb
|-
| || || VI|| Triphalangeal thumb associated with polydactyly
|}
In general the surgical treatment is done for improvement of the thumb function. However, an extra advantage of the surgery is the improvement in appearance of the thumb. In the past, surgical treatment of the triphalangeal thumb was not indicated , but now it is generally agreed that operative treatment improves function and appearance. Because an operation was not indicated in the past, there’s still a population with an untreated triphalangeal thumb. The majority of this population doesn’t want surgery, because the daily functioning of the hand is good. The main obstacle for the untreated patients might not be the diminished function, but the appearance of the triphalangeal thumb.
The timing of surgery differs between Wood and Buck-Gramcko. Wood advises operation between the age of six months and two years, , while Buck-Gramcko advises to operate for all indications before the age of six years.
Thumb
The thumb is the first digit of the hand. When a person is standing in the medical anatomical position , the thumb is the lateral-most digit...
has three phalanges instead of two. Besides the three phalanges, there can also be other malformations. The extra phalanx can vary from a very small phalanx to a full extra phalanx in a more finger-like thumb. It was first described by Columbi in 1559. The true incidence is unknown, but is estimated at 1:25,000 live births. In about two-thirds of the patients with triphalangeal thumbs, there is a hereditary component.
Appearance
The triphalangeal thumb has a different appearance than normal thumbs. The appearance can differ widely; the thumb can be a longer thumb, it can be deviated in the radio-ulnar plane (clinodactylyClinodactyly
-References:...
), thumb strength can be diminished. In the case of a five fingered-hand it has a finger-like appearance, with the position in the plane of the four fingers, thenar muscle deficiency, and additional length. There is often a combination with radial polydactyly
Polydactyly
Polydactyly or polydactylism , also known as hyperdactyly, is a congenital physical anomaly in humans, dogs, and cats having supernumerary fingers or toes....
.
Opposable/non-opposable
An opposable thumb can be placed ‘opposite’ the other four digits or fingers. This function of the thumb is very important for using the hand. It makes precision grips (e.g. key grip, tripod grip) possible. For opposition and therefore precision grips, several factors are necessary: adequate thumb position, adequate length of the thumb, stabile joints and adequate thenar muscle or thumb strength. With a non-opposable thumb, the hand can be less effective in use and therefore be problematic in daily life.Etiology
Malformations of the upper extremities can occur In the third to seventh embryonic week. In some cases the TPT is hereditary. In these cases, there is a mutation on chromosome 7q36. If the TPT is hereditary, it is mostly inherited as an autosomal dominant trait, non-opposable and bilateral. The sporadic cases are mostly opposable and unilateral.Syndromes
Triphalangeal thumb can occur in syndromes but it can also be isolated. The triphalangeal thumb can appear in combination with other malformations or syndromes.Syndromes include:
- Holt-Oram syndromeHolt-Oram syndromeHolt–Oram syndrome is a disorder that affects bones in the arms and hands and may also cause heart problems.-Presentation:All people with this disorder have at least one limb abnormality that affects bones in the wrist . Often, these wrist bone abnormalities can be detected only by X-ray...
- Aase syndromeAase syndromeAase syndrome or Aase-Smith syndrome is a rare inherited disorder characterized by anemia with some joint and skeletal deformities. Aase syndrome is thought to be an autosomal recessive inherited disorder. The genetic basis of the disease is not known...
- Blackfan-Diamond syndrome
- Fanconi pancytopenia
- Townes-Brocks syndromeTownes-Brocks syndromeTownes–Brocks syndrome is a rare genetic disease that affects fewer than 200 people in the entire world. It affects both males and females equally...
Malformations include:
- Radial polydactyly
- SyndactylySyndactylySyndactyly is a condition wherein two or more digits are fused together. It occurs normally in some mammals, such as the siamang and kangaroo, but is an unusual condition in humans.-Classification:...
- Lobster claw hand or foot
Classifications
There are multiple classifications for the triphalangeal thumb. The reason for these different classifications is the heterogeneity in appearance of the TPT.The classification according to Wood describes the shape of the extra phalanx: delta (Fig. 4), rectangular or full phalanx (Table 1). With the classification made by Buck-Gramcko a surgical treatment can be chosen (Table 1). Buck-Gramcko differentiates between six different shapes of the extra phalanx and associated malformations.
Table 1: Classifications of Wood and Buck-Gramcko
{| class="wikitable"
|-
! Classification according to Wood by shape of the extra phalanx !! Shape!! Classification according to Buck-Gramcko by shape/size of extra phalanx and associated malformations !! Shape
|-
| I|| Delta|| I|| Rudimentary triphalangism
|-
| || || II|| Short triangular middle phalanx (brachymesophalangeal)
|-
| II|| Rectangular|| III|| Trapezoidal middle phalanx (intermediate)
|-
| || || IV|| Long rectangular middle phalanx (dolichophalangeal)
|-
| III|| Full|| V|| Hypoplastic triphalangeal thumb
|-
| || || VI|| Triphalangeal thumb associated with polydactyly
|}
Treatment
The goals of surgical treatment are: reducing length of the thumb, creating a good functioning, a stable and non deviated joint and improving the position of the thumb if necessary. Hereby improving function of the hand and thumb.In general the surgical treatment is done for improvement of the thumb function. However, an extra advantage of the surgery is the improvement in appearance of the thumb. In the past, surgical treatment of the triphalangeal thumb was not indicated , but now it is generally agreed that operative treatment improves function and appearance. Because an operation was not indicated in the past, there’s still a population with an untreated triphalangeal thumb. The majority of this population doesn’t want surgery, because the daily functioning of the hand is good. The main obstacle for the untreated patients might not be the diminished function, but the appearance of the triphalangeal thumb.
The timing of surgery differs between Wood and Buck-Gramcko. Wood advises operation between the age of six months and two years, , while Buck-Gramcko advises to operate for all indications before the age of six years.
- For TPT types I and II of the Buck-Gramcko classification, the surgical treatment typically consists of removing the extra phalanx and reconstructing the ulnar collateral ligamentUlnar collateral ligamentUlnar collateral ligament can refer to:* Ulnar collateral ligament * Ulnar collateral ligament * Ulnar collateral ligament...
and the radial collateral ligamentRadial collateral ligamentRadial collateral ligament can refer to:* Radial collateral ligament * Radial collateral ligament * Radial collateral ligament...
if necessary.
- For type III of Buck-Gramcko classification proposable surgical treatments:
- - smaller trapezoidal phalanx and under six years: removal of the extra phalanx and reconstruction of the ulnar collateral ligament. Lengthening of the radial collateral ligament is only indicated when the clinodactyly is still present after reconstruction of the ulnar collateral ligament.
- - trapezoidal phalanx and older than six years: partial removal of the extra phalanx with correction of the angle. ArthrodesisArthrodesisArthrodesis, also known as artificial ankylosis or syndesis, is the artificial induction of joint ossification between two bones via surgery. This is done to relieve intractable pain in a joint which cannot be managed by pain medication, splints, or other normally-indicated treatments. The typical...
of the distal interphalangeal jointDistal interphalangeal jointDistal interphalangeal joint can refer to:* Interphalangeal articulations of hand* Interphalangeal articulations of foot...
(DIP).
- For type IV of Buck-Gramcko classification the surgical treatment typically consists of an osteotomyOsteotomyAn osteotomy is a surgical operation whereby a bone is cut to shorten, lengthen, or change its alignment. It is sometimes performed to correct a hallux valgus, or to straighten a bone that has healed crookedly following a fracture. It is also used to correct a coxa vara, genu valgum, and genu varum...
which reduces the middle phalanx and arthrodesis of the DIP. This gives a shortening of 1 to 1.5 cm. In most cases, this technique is combined with a shortening, rotation and palmar abduction osteotomy at metacarpal level to correct for position and length of the thumb. The extensor tendons and the intrinsic muscles are shortened as well.
- For type V of the Buck-Gramcko classification the surgical treatment proposably consists of a "pollicizationPollicizationPollicization/ is a plastic surgery technique in which a thumb is created from an existing finger. Typically this consists of surgically migrating the index finger to the position of the thumb in patients who are either born without a functional thumb or in patients who have lost their thumb...
". With a pollicization the malpositioned thumb is repositioned, rotated and shortened, the above-described rotation reduction osteotomy of the first metacarpal can be performed as well.
- For type VI of the Buck-Gramcko classification, the surgical treatment typically consists of removing the additional mostly hypoplastic thumb(s). Further procedures of reconstruction of the triphalangeal thumb are performed according to the shape of the extra phalanx as described above.