13.13 Malformations of the hand and wrist

Congenital upper limb anomalies are common with an incidence of 1:506 live births but the variety of anomalies is huge and many are subtle. Approximately 25% of anomalies are syndromic and the variation in hand anomalies helps geneticists identify individual syndromes. The child usually adapts easily to the problem but the impact of anomalies on the parents can be more significant. Despite this adaptation, the surgeon has much to offer in terms of diagnosis, advice, and treatment to improve the function and aesthetics of the hand and upper limb. This chapter gives some general information, a classification of anomalies, and a brief description of the commoner conditions and their treatment. See also Chapter 13.11.

Knowledge of the general principles of upper limb embryology helps in understanding the pattern of some anomalies. Males are more affected than females and although 50% of problems are bilateral, the severity of the condition may differ from side to side. The aetiology is unknown in most cases but in the isolated anomaly genetic causes are unlikely. Often, it is difficult to determine the cause as several aetiologies may result in a similar appearance. Gene defects have been identified for some conditions.

Antenatal diagnosis of some defects, particularly failure of formation, is now common and the surgeon may be called upon for advice at this early stage.

Assessment of the child is based mainly on observation: paying particular attention to features like flexion creases that indicate joint movement. Observe the child’s hand movement and correlate it to normal development. Feel for the presence of bones and move joints to assess passive mobility. Take a family history and assess the whole child and their family to detect inherited conditions.

The timing of surgery in congenital hand anomalies is controversial and as good evidence is lacking, decisions are based on personal preference. Generally, the earlier the reconstruction the better the cortical integration of the reconstructed part and the better the anatomical adaptation. Growth potential is maximized and physical and psychological scarring is minimized.

It is important to emphasize to the parents that they were not responsible for the anomaly and explain briefly why such anomalies have occurred. Reassure the parents that even with the most severe anomalies children adapt amazingly well. Offer psychological and genetic counselling, if you feel it is appropriate. For complex conditions it is wise to watch development over several consultations, to help decide the appropriate intervention and prepare the parents for surgery. Treatment is designed to improve function and allow growth and development. Dysfunction often draws attention to the hand anomaly and conversely improved function often renders the anomaly less noticeable. Functional requirements generally centre on thumb function and its ability to oppose with stability and strength (Box 13.13.1).

The classification of congenital upper limb anomalies is based on current beliefs of their embryological derivation. It was adopted by the International Federation of Surgical Societies of the Hand and is called the IFSSH or Swanson classification. The main categories are divided further according to descriptive or site characteristics (Table 13.13.1).

This group shows arrested limb development. The pattern can be transverse, or longitudinal (Figure 13.13.1). The longitudinal patterns are named according to the affected side.

Radial dysplasia (radial club hand) is the congenital failure of formation in a longitudinal distribution affecting all preaxial or radial structures, resulting most obviously in radial deviation of the wrist. It is defined by the most obvious skeletal deficiency.

The incidence of radial dysplasia is 1:30 000–100 000 live births. Fifty to sixty-six per cent of cases are bilateral but the dysplasia is usually not symmetrical. Right-sided involvement is most frequent and males are twice as commonly affected as females. Radial anomalies are always associated with thumb hypoplasia (except in TAR (thrombocytopenia with absent radius) syndrome) but only 50% of thumb hypoplasia cases are associated with an anomaly of radius.

The aetiology is unknown, and most cases are sporadic. Some are syndromal and some linked to teratogens such as thalidomide, valproeic acid, or radiation. Due to the presumed timing of the congenital insult (the cardiac septum and radius both form in the fifth week), there are many associated disorders (Box 13.13.2).

The pathology of radial dysplasia is well described. The humerus is shorter then normal with distal defects of coronoid, capitellum, and medial condyle that reduce elbow flexion. Most commonly there is complete absence or absence of the distal third of the radius. The fibrous anlage or mesenchymal ‘scar’ that replaces the deficient radius tethers growth producing progressive deformity that includes curvature of the ulna and forearm shortening. The radial carpal bones are absent, hypoplastic or coalesced, especially the scaphoid and trapezium.

The soft tissues are as severely affected as the skeleton with hypoplastic, fused, or absent radial wrist and thumb, extensors, and flexors. In severe cases, the finger flexors/extensors are also affected. The fingers are stiff and this determines the outcome of thumb reconstruction by pollicization. The ulnar digits are less affected.

The radial artery is absent as are several nerves (superficial radial, musculocutaneous, lateral cutaneous nerve of forearm). The median nerve is abnormal, lying quite radial and supplying areas normally supplied by the radial and musculocutaneous nerves.

The classification of radial dysplasia relates to the severity of skeletal involvement but the soft tissue deficiencies are correlated, for example, the absent radius is usually associated with a Blauth type 4 or 5 hypoplastic thumb (except in TAR syndrome). (Table 13.13.2 and Figure 13.13.2).

The clinical presentation is usually obvious at birth: ‘isolated’ thumb anomalies may alert the surgeon to look at the forearm. The hand and wrist are flexed, pronated, palmar subluxed, and radially displaced. The thumb is hypoplastic or absent and the radial digits absent or stiff.

Initial management consists of careful evaluation of the whole child and a passive stretching and splintage regime for the wrist/hand. At this age most postural deformity can be corrected and maintained providing the wrist is splinted continuously. This makes subsequent surgery easier. In all but type 1 and mild type 2 cases, surgery is indicated to stabilize the wrist and later to reconstruct the thumb. Wrist stabilization improves hand position, allows more effective use of the thumb and improves finger flexion strength. There is the additional benefit of improved aesthetics, easier care, and potentially improved ulnar physeal growth. Thumb reconstruction depends on the exact anomaly. Contraindications to surgery include bilateral radial dysplasia, lack of elbow flexion, a very short forearm, severe systemic illness (or an adult who has adjusted to the deformity).

Understandably there are variations in operative technique: some surgeons believe in soft tissue distraction prior to operative reduction and this may be necessary if operative reduction is delayed. If soft tissue distraction is used, apply the distractor at 6–9 months, distract slowly over 2 months, stabilize and then proceed with the definitive operation.

The two definitive wrist procedures are: centralization or radialization.

Correction of the ulna bow may be performed simultaneously or later with forearm lengthening (if required).

The outcome of these procedures should be a short forearm with a neutral stable wrist and prehensile grasp (Figures 13.13.3 and 13.13.4). Complications are common including skin necrosis, pin breakage or infection, recurrent deformity especially carpal subluxation, premature distal ulnar physeal closure, wrist stiffness.

Cleft hand is defined as a congenital longitudinal failure of formation of the central portion of the hand and forearm. It has a very variable presentation from the classic V-shaped central cleft to a single ulnar digit hand (Figure 13.13.5). The incidence is estimated at 1:30 000–100 000 live births. Fifty per cent are bilateral and involve the feet as well. These bilateral cases are familial: autosomal dominant with high penetrance. The aetiology of cleft hand is unknown. The interdigital spaces should form between days 39–50. When this process fails osseous syndactyly occurs whereas if necrosis occurs in the middle of a digit, there is polydactyly and if excess necrosis occurs then a cleft results. Thus cleft hands are frequently seen with syndactyly, polydactyly, osseous fusions, as well as cleft feet (Box 13.13.5).

This category used to include both typical and atypical cleft hands. The latter group are now best classified with symbrachydactyly in the hypoplasia category.

Cleft hands are classified according to their description and the number of digits remaining or by the quality of the thumb and first web as these are important in determining hand function (Manske’s classification) (Tables 13.13.3 and 13.13.4).

Cleft hand presents with absence of the middle finger and to varying degrees the middle metacarpal. Adjacent digits may be absent or present: if present they are often large, frequently syndactylized, and with camptodactyly. With increasing severity the radial side of the cleft becomes absent eventually leaving only the single little finger (Figure 13.13.5B), or in worst cases no digits at all (peromelia). Fusions are often present in the palm but usually there are no carpal anomalies. The intrinsic muscles and long tendons are present but insert anomalously.

Cleft hands are often described as having good function but poor aesthetics. Function can be improved by increasing the first web space, releasing any syndactyly, improving motion at metacarpophalangeal (MCP) joints by excision or release of cross bones, releasing proximal interphalangeal (PIP) joint contractures, performing osteotomies of the metacarpals to align the digits, improving abduction and opposition of the thumb, and providing opposition posts or digits when these are absent. Occasionally straightening and covering a cross bone can create a digit. Aesthetics are improved by the closure of the cleft.

Several techniques exist to create a first web space and close the cleft simultaneously by transposing the cleft skin to the first web and the border digit into the cleft. The Snow–Littler technique uses a palmar-based flap from the cleft transposed to widen the first web space and simultaneously transposing the index finger at the metacarpal base onto the middle finger metacarpal base. The Miura–Komada technique uses the same index transposition but with an incision along the web space and around the digit, and a dorsal extension for access to the metacarpal base minimizing wound problems. The Ueba technique uses the same digit transposition but the flaps lie transverse with the dorsal flap from one side of the cleft and the palmar flap from the other side of the cleft.

Ulnar dysplasia is a longitudinal failure of formation of the ulnar portion of the hand and forearm. It is less common than radial dysplasia occurring in 1:100 000 live births. Most are unilateral with no sex preponderance. It is more common on the left. Half are associated with other musculoskeletal anomalies but unlike radial dysplasia, ulnar dysplasia is not normally associated with systemic anomalies (Box 13.13.6).

Ulnar dysplasia is thought to be due to an injury to the zone of polarizing activity (ZPA). The forearm anomalies are classified according to the ulna and elbow anomalies (Bayne or Baur). Whereas the hand is defined by the Cole and Mansky (1997) classification based on the thumb and first web space (Tables 13.13.5 and 13.13.6) (Figure 13.13.6).

Ulnar dysplasia affects the whole upper limb but the deformity is less obvious and function better when compared with radial dysplasia. The limb is hypoplastic, the ulna possibly absent, the radius bowed, and the elbow unstable. The radial head is dislocated or fused to the humerus (radio humeral synostosis, Figure 13.13.7). In the hand, the digits are hypoplastic or absent and syndactyly occurs in 30%. Seventy per cent have some thumb or first web anomaly.

Splinting and stretches help improve or maintain the wrist position: wrist surgery is rarely indicated. Most surgery is performed to release syndactyly, treat the thumb hypoplasia and first web space deficiency to provide prehension. A rotational humeral osteotomy can help the marked internal rotation deformity and radial osteotomy/lengthening can improve radial curvature if required. Early excision of the fibrous ulnar anlage can prevent progressive bowing of the radius and may result in better growth.

See Chapter 13.11.

Syndactyly is one of the two most common hand anomalies. The term is usually used to describe conjoined digits due to a congenital failure of separation (but it can apply to post-burn or post-trauma ‘fusion’). It occurs in 1:650–2000 births and is twice as common in men as women. Half affect the third web space and only 5% involve the first web space (Figure 13.13.8).

The aetiology is unknown, but 20% are familial usually displaying autosomal dominant inheritance with incomplete penetration and variable expression.

Failure of separation is linked to steroid use in early pregnancy and also fibroblast growth factor receptor deficiency. Some congenital cases are due to trauma and healing as in amniotic band/constriction ring syndrome. Many cases of syndactyly are associated with other syndromes and chromosomal disorders such as Apert’s, Poland’s, symbrachydactyly, and Aarskog’s.

Syndactyly is classified according to site and degree (Table 13.13.7 and Box 13.13.7).

Syndactyly is present at birth although occasionally not noticed until later in life. Assess the web involved: does the failure of separation involve soft tissue, nail, and/or bone. Is the syndactyly causing a deformity?

Hand development occurs rapidly between 6–24 months so it can be important to separate the syndactyly before this period especially if the involved digits are of different lengths.

Surgery involves separation of the digits, creation of a web space and resurfacing of the digits: the circumference of two separate digits is 22% greater than the circumference of conjoined fingers. Problems may arise from the fascial, neurovascular, or tendinous connections running transversely between the digits. The aim is to create a web space sloping at 45 degrees from dorsal to palmar, with a free transverse distal edge, and an aesthetic shape, with minimal scarring on the dorsum of the hand and fingers, no scar contracture, and no longitudinal scars on the digits. In general, avoid separating an adjacent syndactyly simultaneously: staged procedures pose less risk to the vascular supply.

Digital separation is by a zig-zag design, creating interdigitating triangular skin flaps of varying width from the dorsum and palmar aspects of the digits to cover the sides of the separated digits. These flaps avoid longitudinal digital scars that may cause flexion contracture. In digits with symphalangism (such as in Apert’s syndrome) simple longitudinal division is permissible, as flexion contractures cannot occur.

Web reconstruction has many more surgical options: most require full thickness skin grafts to fill the defect created by formation of the web. Most surgeons use a modification of the Bauer design (1956), which creates a dorsal rectangular flap to recreate the web space, or opposing palmar and dorsal triangles, or an omega and anchor design. There are also techniques that avoid skin grafts by redistributing the dorsal digital skin. For complicated syndactyly some surgeons have attempted using distraction of the digital skeleton laterally from the involved web or tissue expansion of the dorsal skin but neither technique is popular due to the high complication rate. Reconstruction of the lateral nail folds is by Buck–Gramcko triangular pulp flaps (Figure 13.13.9).

Injury to digital neurovascular bundles leading to an inability to separate the digits or digital necrosis is the most feared but also the rarest complication.

Distal web creep due to digital scarring and growth is more common in complex syndactyly.

Deformity of the digit usually a flexion and lateral curvature due to scarring and growth disturbance from the length inequality between the syndactylized digits is common particularly in border digit involvement.

When skin grafts are used there is the risk of hyperpigmentation or hair growth of the skin graft. Skin graft loss or flap necrosis can lead to delayed healing and scarring.

Camptodactyly is defined as a congenital flexion deformity of the PIP joint. It affects 1% of the population but is under-reported. It can be subtle and is sometimes only noticed late, giving two peaks of presentation: early childhood and adolescence. In adolescence it often presents after trauma although this is not the cause. There is a female preponderance in the adolescent group. Camptodactyly is most frequent in the little finger. Some cases are familial (autosomal dominant).

Camptodactyly results from a congenital imbalance of the flexion and extension forces at the PIP joint. The theories of causation include abnormal intrinsics, anomalous finger flexors or extensors.

Camptodactyly presents with a flexion deformity at the PIP joint but from this position, full flexion is possible. Rarely the deformity is fixed. A history of preceding trauma is common but unrelated. Lateral x-rays in adolescents show characteristic changes at the PIP joint (Figure 13.13.10). In addition on the anteroposterior view the PIP joint slopes to the ulnar aspect and clinically a ‘ulnar drift’ of the middle and distal phalanges is noted. Though rarely found, always check for dysfunction of the ulnar nerve, intrinsic muscles, and the flexor digitorum superficialis (FDS).

Splinting and stretches are used first. In most cases this improves the contracture sufficiently. If conservative therapy fails and the contracture is greater than 50–70 degrees then surgery can be considered. The principles of surgery involve release of the skin, soft tissues, and joint, an attempt to rebalance flexor and extensor forces, and reconstruction of the skin defect. The options are: exploration for specific anomalies, resection and/or release of the anomaly and then splintage, or tendon transfers to augment extension at the central slip utilizing the lumbrical, FDS, extensor indicis profundus (EIP), or extensor plication. Alternatively the FDS lasso procedure can increase MCP flexion, helping transfer some of the extensor pull to the central slip.

In older patients with established PIP joint changes not amenable to soft tissue correction an osteotomy can be performed at the proximal phalangeal neck to correct flexion and inclination.

A discrepancy between the size of the pulley and the size of the flexor tendon leads to a flexion contracture of the digit or less commonly triggering as seen in adults. Thumbs are most commonly affected. The aetiology is unknown.

It is not usually apparent at birth but becomes noticeable in the first year of age, or occasionally later.

The child presents with a digit locked in flexion or extension and a palpable nodule on the flexor tendon may be felt called Notta’s node.

Reports suggest that 33% of trigger thumbs resolve with stretches and splinting if the tendon is mobile (triggering) on presentation but they do not improve sufficiently to allow normal interphalangeal (IP) joint hyperextension. Operative release of the A1 pulley should be performed. Finger triggering does not resolve spontaneously and should be treated operatively. Steroid injections are not indicated unless there is other pathology such as diabetes or inflammatory arthritis.

An anomaly where the thumb is flexed into the palm and no active extension is seen. The clasp thumb can be passively extended. This is normal behaviour in babies under 6 weeks and should not be confused with the fixed thumb-in-palm deformity.

The incidence is unknown as is the aetiology. Some cases are due to hypoplasia of extensor pollicis longus (EPL). It can occur in association with Digitotalar syndrome, Freeman–Sheldon ‘whistling face syndrome’ and arthrogryposis or it may be the first presentation of thumb hypoplasia or mild radial club hand.

Clasp thumb was classified by Weckesser according to severity or clumped together by McCarroll into supple (having an absent EPL) or complex (an absent EPL with a flexion contracture of the MCP joint and thumb hypoplasia) (Table 13.13.8).

If the child is young, reassure the parents that this is probably normal and reflects a mild imbalance of flexor and extensor development. Initially it is treated by splinting the thumb in extension. This is usually successful. In resistant or complex cases surgical management may be needed with tendon transfer to reconstruct the absent EPL. The EIP is often absent and cannot be used. Complex thumbs may need extensive palmar skin release, and thumb hypoplasia reconstruction as well.

Polydactyly is the formation of all or a part of an extra digit. It is the commonest congenital upper limb anomaly (Figure 13.13.11). The aetiology is unknown. It can be hereditary especially when the little finger is involved. Polydactyly is associated with many syndromes (Table 13.13.9 and Box 13.13.8).

Thumb duplication is common, it differs from other digital polydactyly in the complexity of the duplication, the functional importance of the thumb, and hence the reconstruction.

Wassel based his classification of thumb duplication on the most proximal extent of the duplication (Table 13.13.10 and Figure 13.13.13). The commonest type is type 4, next commonest is type 2, then type 6. Note that types with even numbers are duplications which extend to joint level. A Stelling A polydactyly-type duplication of the thumb where there is a small nubbin of a thumb connected by a thin soft tissue pedicle (usually at the level of the metacarpophalangeal joint) is not covered adequately by this classification, but is sometimes described as a rudimentary thumb.

Treatment does not consist of simple excision of the extra thumb. Prior to excision assess the level of the duplication, the development and stability of the joints, and the degree of axial deviation of each element. Excision of the most hypoplastic thumb is combined with osteotomies, and reconstruction of the collateral ligaments. Osteotomies are needed to align the joint surfaces, the axis of the phalanges and to thin the widened metacarpal or phalangeal head. Division of intertendinous connections and realignment of the flexor and extensor tendon may also be needed.

In many cases the remaining thumb is smaller then the opposite thumb, and stiffer. This does not substantially affect function, but should be pointed out to the parents pre-operatively. It is common to reoperate for a subsequent zigzag deformity if initial osteotomies are not performed.

Brachydactyly describes short fingers usually due to an autosomally dominant inherited condition. These are sometimes syndromic such as in achondroplasia, or part of a systemic condition like pseudohypoparathyroidism (with short metacarpals), but most commonly are asymptomatic and often unnoticed such as little finger clinodactyly.

Good function means intervention is usually not required. Associated conditions such as syndactyly will need treatment. Occasionally a functional problem such as a palpable and painful short metacarpal head in palmar grip or a finger deformity that impacts on function will require surgery. Longitudinally bracketed epiphyses in delta phalanges may benefit from epiphyseolysis. Mature deformities causing functional problems can be corrected by osteotomies. Lengthening is rarely indicated.

Symbrachydactyly, translated as short fingers joined together, represents a spectrum of failure of digital development with a tendency to preserve the thumb (in contrast to a similar spectrum of cleft hand which preserves the little finger).

The incidence of symbrachydactyly is 1:10 000. The inheritance is mostly sporadic. The aetiology is unknown but thought to be a mesodermal defect of vascular origin leaving ectodermal remnants such as skin and nails as nubbins. It usually affects the left side but when associated with Poland’s syndrome affects the right.

Symbrachydactyly has a spectrum of severity: the best cases have all digits and all phalanges present but the fingers are slightly shorter and stiffer whilst at the other extreme, in essence there is a transverse failure of formation that may be through the level of the forearm. The rudimentary digital remnants suggest a symbrachydactyly rather than a reduction defect.

In between these two extremes there are reducing patterns of digital loss described as a teratologic sequence starting with loss of the middle phalanges, then the distal phalanges, then the metacarpals as well. The pattern of loss tends to be more severe on the ulnar side sparing the thumb initially. The pattern with short/absent middle fingers preserving the thumb and little finger was called an atypical or U-shaped cleft hand, as compared to the classical V-shaped cleft pattern (Figure 13.13.14).

In symbrachydactyly with short fingers no intervention is indicated, as function is good. Where digits are absent, the number of remaining digits and their function determines treatment. The quality of the thumb and first web space determine the final functional outcome.

Operatively consider whether the hand would benefit from first web space release/deepening, would lengthening of the thumb or other digits improve grasp and pinch? Methods of achieving the latter include vascularized or non-vascularized toe transplant and distraction lengthening of existing parts.

Non-vascularized toe phalanx transfer is very much a second choice option. The donor site leaves an ugly defect once growth occurs as the growth in the remaining middle and distal phalanx is reduced by 50%. The donor defect can be minimized by suturing the flexor to extensor tendons or by bone graft from iliac crest. One expects growth of approximately 1mm per year, eventually achieving approximately 78% of the length of contralateral toe phalanx, or 52% of opposite digital phalanx. This type of transfer results in better growth if performed before 15 months of age.

Congenital hypoplasia or aplasia of the thumb may be categorized either in the failure of formation or in the hypoplasia category of the IFSSH classification. It is common and may be an isolated phenomenon or part of a radial dysplasia, cleft hand, or symbrachydactyly. The aetiology is unknown but has been linked to fetal neurogenic injury and thalidomide.

Thumb hypoplasia presents with a very predictable pattern and is classified according to Blauth (1967). This classification does not cover transverse absences of the thumb due to different pathologies (Figure 13.13.15 and Table 13.13.11).

Surgery aims to increase function and appearance of the hand. Try to reconstruct all the deficiencies in one operation and do this before 1 year of age to encourage full thumb function (Box 13.13.9).

The MCP joint stabilization and UCL reconstruction is achieved by UCL plication or soft tissue gubbinsoplasty where tissue allows or, if necessary, with a tendon graft (palmaris longus or extensor digiti minimi) or use the end of the tendon used for the opponensplasty.

Pollicization creates a thumb by the transposition, stabilizing and shortening of a finger ray (usually the index). The index MCP joint becomes the basal joint of the new thumb, the PIP joint becomes the new MCP joint, and the DIP joint becomes the new IP joint. A first web space must also be created.

The outcome of pollicization depends more on the quality of the index finger and the presence of intrinsics and other musculotendinous structures than the surgical procedure. Complications include overgrowth of the trapezium due to persistence of the physis, stiffness, instability usually due to hyperextension of the new carpometacarpal (CMC) joint, lack of flexion or extension due to tendon imbalance, poor opposition either due to inadequate rotation or poor intrinsics, poor position of thumb and skin flap necrosis.

Pectoral and hand anomalies were described in 1841 by Alfred Poland, a medical student at Guy’s Hospital, London. With an incidence of 1:20 000–30 000 the condition is rare but well known. The sex ratio is equal but the right side is affected twice as commonly as the left. The aetiology is unknown but there are a few families identified with an inherited form. Left-sided Poland’s syndrome is also linked with leukaemia, non-Hodgkin’s lymphoma, and dextrocardia. The current theory is that the musculoskeletal malformations seen in Poland’s and symbrachydactyly stem from a disrupted subclavian artery occurring in the sixth week of gestation as the ribs grow forward and medially causing a subclavian artery kink and the subclavlan artery supply disruption sequence.

In Poland’s syndrome the hand anomaly is the most obvious defect. It varies from syndactyly and symbrachydactyly to amputation. The upper limb girdle and chest anomalies are less obvious but consist of a hypoplastic forearm or arm, an absent sternal (and sometimes clavicular) head of pectoralis major, deficiency or absence of pectoralis minor, latissimus dorsi, serratus anterior and other shoulder muscles, hypoplastic breast and nipple, abnormal ribs and costal cartilages with deficient subcutaneous fat and axillary hair, and the sternum may rotate to the involved side causing a contralateral carinatum deformity.

The hand conditions are treated appropriately by syndactyly correction or by deepening the webs to create the illusion of longer fingers. The first web often needs a flap to deepen and widen it. The deformity of the rib cage occasionally requires surgical correction. The anterior axillary fold is reconstructed by using a latissimus dorsi transposition by detaching its insertion and transferring it forward on the humerus or by contralateral latissimus dorsi free flap transfer if the muscle is absent.

Females may need tissue expansion of their breast through puberty, followed by a permanent implant. The thin chest subcutaneous tissue will need simultaneous latissimus dorsi transfer. There are autologous tissue alternatives.

Congenital overgrowth of a digit is rare (2:100 000 live births, 1% of all congenital anomalies). It may be a component of other hypertrophic conditions or gigantism. Ninety per cent are unilateral but involving more than one digit. The index and middle digits are most commonly affected: distally more than proximally (Figure 13.13.16). The cause is unknown but probably varies with the type of overgrowth. There is a theory that the commonest type ‘progressively growing lipofibromatous nerve overgrowth’ is related to neural growth factors (Box 13.13.10).

Primary macrodactyly has generalized soft tissue enlargement of lipofibromatous tissue. This follows a nerve-like distribution and so often affects one side of a digit or ray, frequently following the median nerve.

Secondary macrodactyly may occur with a variety of conditions.

Pathologically four types have been described: lipofibromatous, neurofibromatous, hyperostotic, hemihypertrophy or Proteus syndrome.

Surgery is indicated for poor function or cosmetic concerns. Surgery aims to create a relatively normal sized digit with some function. The operative options are amputation; reduction (by combination of bone excision, osteotomies to correct angulation and soft tissue excision perhaps including the nerve); epiphysiodesis (if at age 10 the digit is already the size of the parents). Reduction of a macrodactyly is performed through a midlateral incision on the convex side of the digit, extending in an L-shaped pattern at the pulp. Excise the fat, enlarged digital nerve, and the overlying skin. Perform a closing wedge osteotomy of the proximal phalanx and excise sufficient middle and distal phalanx to shorten the digit and fuse the DIP joint. A nail partial excision to reduce the length and width of the nail will complete the procedure. Secondary surgery is often required.

Amniotic band syndrome is a congenital disorder mostly affecting the limbs but occasionally seen around the trunk and face. It is thought to be caused by amniotic bands that wind around extremities, possibly related to perforation of the amniotic sac but alternative theories do exist. Interestingly 50% have more than one limb affected. It occurs in 1:2000–15 000 births. There is an association with oligohydramnios, cleft lip and palate, and talipes. The central digits and the hands are most commonly affected (Table 13.13.12).

Clinically, the appearances are diagnostic for types 1, 2, and 3. With amputation the diagnosis is more difficult, though unlike symbrachydactyly there is tapering of the stumps and there are no nail remnants. X-rays show amputation occurring through bone or joint and the remaining part is not hypoplastic. The proximal soft tissue structures are all present, influencing reconstruction. The band if deep may involve or divide major nerves or vessels resulting in altered sensibility or a temperature difference below the band even after treatment.

Treatment involves multiple Z-plasties around the band releasing the constriction and flattening the depression by re-distribution of periband fat. Release of any acrosyndactyly should be done before any growth disturbance occurs. In cases with amputation consider lengthening the thumb by distraction, toe transfer or on-top plasty (extending the length of the thumb by moving the index stump on top).

Surgery should be preformed very early if there is any vascular compromise, severe lymphoedema or acrosyndactyly affecting development. Late treatment of distal lymphoedema or macrodactyly may be needed.

The management of arthrogryposis is multidisciplinary. Initially stretches and splinting aim to maintain joint movement with the ultimate goal for the hands to be used at the desk top rather than the traditional aim of one hand extended for toileting and the other flexed for feeding. Management is influenced by the fact that sensation is normal and the patient is usually well motivated.

In 1878, Madelung described a congenital ‘dinner-fork’ deformity of the distal radius and wrist but credited Dupuytren. This is an inheritable, autosomal dominant condition with incomplete penetrance. It is usually bilateral affecting females more than males. The anomaly occurs on the ulnar palmar aspect of the distal radial growth plate such that the radial side grows but an abnormal bone bar on the ulnar side tethers growth. This leads to early closure of ulnar aspect of distal radial physis. The tether is thought to be an abnormal radiolunate ligament. Madelung’s deformity is associated with achondroplasia, Turner’s, nail-patella syndrome, Leri–Weill mesomelic dwarfism, dyschondrostosis, and with the SHOX (short stature homeobox) gene. This gene affects the mid portion of the limbs, so sitting height is near normal.

Madelung’s presents usually at age 8–12 years with a spontaneous palmar subluxation of the wrist with increasing radiopalmar and ulnar tilt due to abnormal growth forces, producing a dinner fork-like deformity. Radiographically there is a short bowed radius whose articular surface is inclined in a palmar and ulnar direction. The ulna head is prominent dorsally and a triangular-shaped proximal carpus has the lunate apparently retracted in between the radius and ulna leading to ulna carpal impingement (Figure 13.13.17).

Observation and reassurance is the main method of management as most patients have excellent function. Surgery is considered if there is pain secondary to impingement, degeneration, or gross deformity.

If the patient presents before skeletal maturity consider an epiphysiolysis and release of the tight tethering radiolunate ligament. After skeletal maturity consider a volar approach releasing the pronator quadratus and radiolunate ligament, followed by a dome osteotomy of the radius to rotate the distal radius into a better position. An ulnar shortening may also be necessary.