CHAPTER
60

Operations for congenital hand differences are rarely a medical emergency. The pediatric upper extremity undergoes rapid changes in size during the first few years of life, and as the structures get larger they are easier to identify and reconstruct.1 As such, allowing the patient time to grow before performing the initial surgical correction allows for the opportunity for greater precision in the execution of the surgical treatment plan. Notable exceptions to this are cases of neonatal compartment syndrome and impending limb loss (vascular compromise) associated with amniotic disruption sequence.^2,3

An additional aspect of surgical timing to be cognizant of is the recognition that, because of the constant anatomic changes resulting from growth and development, even if a result looks aesthetically flawless immediately after the procedure, there is (unfortunately) no guarantee that this degree of perfection will persist ad infinitum. An example of this type of “postponed surgical complication” is clearly evident when, for example, damage is incurred to the growth plates or neurovascular structures. The underlying damage, though not immediately seen postoperatively, can result in angular deformities or undergrowth of a bone or part of the hand months or years later. Conversely, leaving osteogenic tissue after removing extra bones can result in regrowing of part of the removed bone with functional and cosmetic impairment.

A defined period of rapid hand growth occurs from birth through the first few years of life.1 Therefore delaying surgery, if possible, until the patient is 2 to 3 years old makes the procedure technically easier and yields a result that may be at decreased risk to deteriorate over time (i.e., at skeletal maturity).

Physiology of Wound Healing

As discussed in Tachdjian’s Pediatric Orthopaedics, “another unique characteristic of a child’s hand is the increased risk for a disproportionately thick scar created in infants’ skin at the site of hand incisions … Fetal skin has the remarkable characteristic of healing without scarring … soon after birth the infant skin may make an unexpectedly robust, hypertrophic scar at the site of surgical incisions. This is in contrast to the more favorable nature of deep scarring around the tendons and joints of older children. This superficial hypertrophy of the scar in the skin incision is particularly a problem for the hand surgeon because the hand’s great mobility demands absence of scar in areas of the skin that change length with hand motion.”⁴

Development of Functional Skills

The developmental stage of the child is also an important factor in achieving a good result after surgery. This is particularly true when a certain level of cognitive development is imperative to successful treatment of a condition.

A prime example of this “developmental requirement” is in patients with a hypoplastic thumb. Throughout the first 3 months of life, the thumb is primarily in a palmar position. At this stage, the thumb is merely an accessory appendage and functions more as a pacifier than anything else. How ever, by 9 months, as the child begins the exploration of the environment in earnest, the thumb gains its independence. Mobility from the palm begins commensurate with new functional demands. At 12 months, the thumb has become a critical portion of the hand and serves a multitude of functions.⁵ Therefore a clear assessment about strength and mobility cannot accurately be achieved before reaching this level of cognitive and motor development. This can be very important, because determination of prehensile grasp patterns is mandatory in determining proper surgical treatment for these patients.

Aspects Associated with Anesthesiology

Another aspect in determining the appropriate timing for a surgical intervention is to weigh the risks and benefits associated with the exposure to general anesthetics in the infant. In the past, anesthesia was avoided in very young patients (younger than 6 months), if possible, because of perceived increased risks related to the metabolism of the anesthetic. In addition, recent preclinical and animal trials have yielded data that demonstrate a possible correlation with decreases in neurodevelopment when multiple anesthetics are given at a young age; however, conclusive studies are still ongoing. The exact age that this risk decreases is still to be determined, but presumably the older the patient the less the risk.^6,7

Additional Considerations

Significant external pressure can be placed on the surgeon by the patient’s family to perform early surgical intervention because of the aesthetic appearance, but this should not influence timing of surgery. An extensive discussion with the parents usually is sufficient to allay concerns and delay surgery until a more appropriate time.

Also importantly, the hand surgeon must be aware of the comorbidities that are often present in patients with congenital hand differences. Such comorbidities (e.g., Fanconi anemia, thrombocytopenia absent radius) often have the potential to significantly affect treatment in myriad ways and are discussed in the following section.

Associated Anomalies

Completing a detailed medical history, comprehensive review of systems, and thorough clinical examination are a critical first step in the evaluation of a child with a complex hand anomaly. Children with hand anomalies can also have serious visceral and systemic anomalies that can take precedence over the treatment for anomalies of the hand. As well, medical conditions associated with complex hand differences are often not directly related to the affected limb. As such, they can easily be missed or “glossed over” if not properly evaluated, with the resultant consequences of this error leading to severe morbidity or even mortality.

Examples of congenital upper limb differences that are associated with other malformations of the musculoskeletal system are listed in Table 60.1.

Table 60.1 Congenital upper limb differences associated with other malformations

The design of skin incisions and flaps is paramount and more critical in a child’s hand than in an adult’s because of the degree of scarring that can occur. It is well known that tension on a scar leads to scar hypertrophy and can result in restricted movement. Fig. 60.1 illustrates the fundamental principles for the correct design of incisions along fingers.⁴ The incisions are based on the axis of rotation of the interphalangeal (IP) joints. The connection of these lines results in three digital diamonds. These diamond-shaped fields contain skin that changes length with finger motion. Any longitudinal scar located within these diamonds will therefore be under significant tension, possibly causing scar hypertrophy and contracture.⁴

In particular, scars placed in the first web space lead to restricted movement of the thumb. The great mobility of the human thumb is conferred by a specific geometric arrangement of the first web space. The volume of the tissue in the first web space is a tetrahedron covered with supple palmar and dorsal triangles of skin. As such, no suture line should cross the leading edge of the first web space. This is particularly important in pollicization operations. In this instance, we recommend using a modified racquet incision⁹ (Fig. 60.2), so that the sutures will align on the dorsal tetrahedron border of the first web space.

Fig. 60.1 The illustrative principles underlying the correct design of finger incisions. (a) The incisions are based on the axis of rotation for the interphalangeal joints. (b) The palmar view shows the three digital diamonds containing skin that changes length with finger motion. Any longitudinal scar located within these diamonds will hypertrophy and contract. (c) In full digital flexion, points 1, 2, 3, and 4 touch, as do the side limbs of the diamonds, to maintain length. (Reproduced from Herring JA, ed. Tachdjian’s Pediatric Orthopaedics. 4th ed. Philadelphia, PA: Elsevier Saunders; 2008:490.)

Fig. 60.2 Modified racquet incision as described by Marybeth Ezaki, MD, and Peter Carter, MD. (a) Volar. (b) Radial. (c) Dorsal.

Fig. 60.3 Flap design for syndactyly. The dorsal flap is designed first. To define the starting point of the flap, the metacarpal heads are identified by flexing the metacarpophalangeal joints. (a) It is important to extend the tip of the flap at least two thirds of the way to the proximal interphalangeal (PIP) joint to obtain a flap of adequate length to prevent an incision line in the web space. (b) Then, the dorsal incision is designed. (c) Finally, the palmar incision is made.

Fig. 60.4 A linear scar resulted in a flexion contracture

Fig. 60.5 Straight-line separation may be appropriate for patients with Apert’s syndrome because of the lack of significant interphalangeal motion.

Another example of the need for careful incision planning involves syndactyly reconstruction, which is one of the most common congenital hand differences encountered. The success of any syndactyly reconstruction is largely dependent upon the design of the skin incision and flaps. In the majority of cases a dorsal flap is used to reconstruct the web space. There are many designs for the dorsal flap, but the primary objectives are for a tension-free closure and appropriately placed scars. We prefer a standard dorsal flap design, which is designed as shown in Fig. 60.3. It is important to extend the tip of the flap at least two thirds of the way to the proximal interphalangeal (PIP) joint, because this provides adequate length to prevent an incision line in the web space. If undue tension exists at the incision line, this eventually will retract into the web space and possibly cause a web space contracture.

Further considerations in syndactyly reconstruction include designing appropriate opposing zig zag flaps to avoid linear scars that would otherwise result in contracture (Fig. 60.4). If not designed correctly, this can lead to increased scar contracture and the need for more skin grafting than usual, which can affect donor site location. An exception to this may be in the complex syndactyly reconstruction in an Apert’s patient with no significant IP motion when straight-line separation may be appropriate (Fig. 60.5, Video 60.1).

Skin Grafts

Skin grafts are required when there is not enough local skin to cover a defect. The use of skin grafts requires both functional and cosmetic assessment of the recipient site. Ideally, a skin graft should have a similar color scheme to the recipient site, minimal contracture during healing, minimal hair growth, and ability to grow with the patient. We have found that full-thickness skin grafts obtained from the volar wrist crease meet these requirements best; however, if a substantial amount of graft is required (as is sometimes the case in Apert’s or complex polysyndactyly reconstruction), an alternate site must be used. In particular, the volar-ulnar side of the wrist is ideal because it offers hairless skin, even in the hairiest male, that many other donor sites do not provide.

The area is very forgiving in young patients because it can be closed with minimal risk of wrist contracture. In addition, this area can be repeatedly used in cases of staged reconstruction or revisions.

An additional benefit is that the entire area is covered by the same dressing or cast throughout the healing period. As in any full-thickness skin graft, proper preparation is required, as is minimal tension when inserting. Loss of graft can result in web creep, contracture, or hypertrophic scarring.

Fig. 60.6 Severe web creep and contracture after loss of graft.

Skin flap necrosis can easily occur in this patient population if care is not taken during the design and mobilization of the flaps. It is important to keep the base of the flaps as wide as possible with mobilization of the flap in the proper plane to provide adequate perfusion all the way to the tip of the flap. Failure to perform this correctly will lead to flap death with secondary healing of the area that can cause severe contracture. This is especially important in cases of syndactyly reconstruction where flap loss can result in web creep and/or finger contracture which can be severe (Fig. 60.6). It is also important in cases of hypoplastic thumb reconstruction when the first web space reconstruction is performed using z-plasties. If these flaps do not survive, the result can be a severely contracted first web space which can be very difficult to treat by revision surgery.

Joint Instability

Joint instability can be a significant component of many congenital hand difference conditions. Depending on whether this involves a finger or a thumb as well as which specific joint is involved has significant implications on hand function. If untreated, this can lead to joint degenerative changes along with pain. This complication is most often seen in the setting of complex syndactylies, preaxial (radial) polydactylies, and hypoplastic thumb reconstruction.

The bony synostosis that exists in patients with complex syndactylies usually is between the tufts of the distal phalanges. Tip separation should be from proximal to distal after identification and preservation of the collateral ligaments of the DIP joints. If done in the opposite direction, injury to the collateral ligaments can occur, resulting in gross instability of the DIP joint that is not easily repaired (Fig. 60.7).

In preaxial (radial) polydactyly, specifically in the most common variation (Wassel type IV), reconstruction of ligaments and tendons is especially critical, unlike a simple excision performed in postaxial (ulnar) type B polydactyly. It is imperative that the radial collateral ligament of the metacarpophalangeal (MCP) joint is transferred from the thumb to be excised to the thumb that is being reconstructed. Distally, the insertion is taken down with a strip of periosteum to facilitate reattachment, while proximally care must be taken during the chondroplasty procedure of the metacarpal head to avoid detachment of the origin. Failure to do this can lead to significant joint instability and degenerative changes. Both are very difficult to treat and usually require a chondrodesis or fusion procedure4 (Fig. 60.8).

One of the specific problems associated with type II and III hypoplastic thumbs in radial longitudinal deficiency is ulnar or radial MCP joint instability. Stabilization of this lax joint can be accomplished by several modalities. Because these patients also require opponensplasties, our preferred technique is to use the FDS ring opposition transfer. This procedure enables us to split the end of the tendon to reconstruct the UCL, RCL, or both as part of the same procedure¹⁰ (Fig. 60.9).

A free tendon graft reconstruction is another possibility, although care must be taken in patients with open physes to avoid creating a bone tunnel that injures this important area, resulting in growth arrest. At times global instability of the MP joint exists that is not amenable to effective reconstruction. Although technically difficult, a chondrodesis can be an option in young patients. The cartilaginous surface is carefully removed from the base of the proximal phalanx up to the level of the physis, as is the surface of the metacarpal head. This can be a technically challenging procedure and may eventually require bony fusion when the patient is older.

Fig. 60.7 (a) Complex syndactyly with bony synostosis at the distal phalanx seen on a radiographic study. (b) Dorsal view of the complex syndactyly. (c) Flexion creases on the volar view indicate the presence of flexor tendons.

Fig. 60.8 (a) Transfer of the collateral ligament of the metacarpophalangeal (MCP) joint in preaxial (radial) polydactyly. (b) The collateral ligament has to be carefully detached as far distally as possible while preserving the origin of the ligament (off the broad metacarpal head); a cuff of radial periosteum together with the collateral ligament is carefully sharply dissected. (c) The chondroplasty technique. (c Reproduced from Herring JA, ed. Tachdjian’s Pediatric Orthopaedics. 4th ed. Philadelphia, PA: Elsevier Saunders; 2008:490.)

Fig. 60.9 FDS ring opposition transfer. (a) The ring finger FDS tendon is isolated and cut at the ring finger base. (b) Then the FDS tendon is brought around the FCU tendon and passed through a subcutaneous tunnel to the radial side of the thumb.

Despite finding radiographic nonunion at this juncture in up to 20% of our patients following pollicization, only 3.5% of our patients had clinical instability that required additional procedures.11

Axial Deformities

Axial deformities can be encountered frequently in congenital hand difference diagnoses. This can manifest itself as angulation or malrotation. Radial polydactyly patients frequently have angular deformities that can not only affect function but also the aesthetic result. The cause is not the same in every instance and must be analyzed and addressed thoroughly during the initial reconstructive procedure. In Wassel type IV radial polydactyly, a zig zag deformity may be present because of aberrant positioning of the flexor and extensor tendons or positioning of the bifid metacarpal head (Fig. 60.10). In an attempt to correct this, recentralization of flexor and extensor tendons, in addition to osteotomies, is performed⁴ (Fig. 60.11). In some cases the angular deformity is related to joint instability and may require fusion at a later date.

Patients with clinodactyly present with angulation that may be the result of either an abnormally shaped phalanx or a delta phalanx (bracket epiphysis). Before the age of 2 years this may be very difficult to assess radiographically. If a true bracketed epiphysis is noted, this can be effectively treated with excision of the bracket and fat interposition. If abnormal phalanx shape is noted without bracket, then opening wedge osteotomy may be appropriate, as reported previously.¹² Angular deformities of the thumb can also be seen, especially in patients with Apert’s or Rubinstein-Taybi syndromes. When identified, this can be treated as shown in Fig. 60.12. This involves designing VY-YV skin flaps, releasing abnormal insertion of thenars (if present), and performing a dome osteotomy of the proximal phalanx. Careful preoperative evaluation of patients with Rubinstein-Taybi syndrome must be performed, because cardiac anomalies may be present and prohibit safe surgery.

Fig. 60.10 Wassel type IV preaxial (radial) polydactyly. (a) An aberrant positioning of the flexor and extensor tendons exacerbates the zig zag deformity. (b) Radiograph of the deformity.

Fig. 60.11 With marked angulation of the remaining articular facet, a supracondylar osteotomy of the metacarpal is indicated. Importantly, this is performed proximal to the origin of the collateral ligaments. (Reproduced from Herring JA, ed. Tachdjian’s Pediatric Orthopaedics. 4th ed. Philadelphia, PA: Elsevier Saunders; 2008:490.)

Fig. 60.12 (a) Angular deformities of the thumb. (b) VY-YV flaps design. (c,d) Result after thenar release, dome osteotomy, and closure of the VY-YV skin flaps.

Fig. 60.13 (a) Illustration of Buck-Gramcko technique. (b,c) Preoperative and postoperative clinical example. (a Reproduced from Herring JA, ed. Tachdjian’s Pediatric Orthopaedics. 4th ed. Philadelphia, PA: Elsevier Saunders; 2008:490.)

Nail deformities can be a significant complaint of patients and parents after reconstruction of complete syndactylies. At the initial reconstruction, the hyponychial and paronychial folds need to be reconstructed with tissue that resembles what would normally be present. The best option is glabrous tissue, which can be obtained from either composite grafts from the hypothenar eminence or toe or Buck-Gramcko tip flaps4,13 (Fig. 60.13). Full-thickness skin grafts alone are not adequate and will lead to significant nail deformity.

The Bilhaut-Cloquet procedure, or modifications of it, has been used effectively in correction of preaxial (radial) polydactyly Wassel/Flatt types I and II. However, nail closure is critical. Removal of the nail plate and careful, accurate closure of the sterile and germinal matrix are essential to provide the best nail later. Even then, a groove or ridge is essentially always present (Fig. 60.14).

Unrealistic Expectations

Patients and their families often evaluate the success (or failure) of their surgery based on assumptions that have very little to do with the technical quality of the care they received.¹⁴ This is particularly true given that most parents, understandably, lack a sophisticated understanding of the underlying pathology and associated factors affecting the ultimate outcome. Recent evidence has suggested that there are a multitude of individual differences and external variables that underlie how patients (and their families) evaluate their satisfaction with surgery.15 Although a comprehensive review of all of these variables is outside the scope of this section, some important clinical pearls are addressed that can be easily incorporated by treating physicians to maximize patient satisfaction and establish realistic expectations for the aims (and possible outcomes) for surgery.

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