Pseudosyndactyly, a mitten deformity of the hand, is a serious problem that can arise in children with recessive dystrophic epidermolysis bullosa (EB). The authors present 2 cases of patients who developed significant contractures of their hands with limited functional use secondary to pseudosyndactyly. At the time of both initial operations, digit separation and contracture releases were performed, which resulted in large areas of denuded skin on the palmar and volar aspect of the fingers and hand. A biologic tissue matrix (Integra™ Bilayer Matrix Wound Dressing, Integra Lifesciences Corp., Plainsboro, NJ) was used initially to cover the wounds. Subsequently, a bioengineered skin equivalent (Apligraf™, Organogenesis Inc., Canton, Mass) was used for epidermal coverage. The biologic tissue matrix was selected because of its excellent tensile strength, flexible adherent covering, and success with decreasing the incidence of postoperative wound contracture, which the authors believed was necessary for the hands to heal successfully. Skin grafting was not an option in either case because the patients did not have any suitable harvest sites secondary to the generalized blistering as a result of the epidermolysis bullosa. The bioengineered skin equivalent was used to promote reepithelization of the neodermis created by the biologic tissue matrix by delivering multiple growth factors and cytokines.

       Epidermolysis bullosa (EB) is a group of inherited disorders characterized by mucosal lesions and bulla formation typically following mechanical trauma. Autosomal dominant and recessive forms of EB have been identified with 23 documented subtypes. Classification of EB is based on the level of blister cleavage—EB simplex occurs at the epidermal level, junctional EB at the lamina lucida, and dystrophic EB at the dermis.^1,2
       Skin and mucosal involvement in EB ranges from mild to severe. Blistering in EB simplex usually occurs without scar formation because shearing is within the epidermis, and blisters may be localized to the hands and feet. Junctional EB may involve the gastrointestinal, genitourinary, and respiratory tracts with extensive denudation severe enough to cause neonatal death. Gastrointestinal involvement and large areas of denuded skin may also be present in the recessive form of dystrophic EB. In addition to being more severe than the dominant form, recessive dystrophic EB is occasionally associated with a mitten deformity of the hands caused by pseudosyndactyly.²
       Surgical management of the mitten deformity involves degloving the hand, digit separation, and contracture release. Split- or full-thickness skin grafts and splints aid in healing.² Use of bioengineered skin equivalent (BSE; Apligraf™, Organogenesis Inc., Canton, Mass) following surgical release of mitten deformity has been reported to increase range of motion and maintain web space.³ The authors used a biologic tissue matrix (BTM; Integra™ Bilayer Matrix Wound Dressing, Integra Lifesciences, Plainsboro, NJ) for initial severe mitten deformity contracture release primarily due to its excellent tensile strength, flexible adherent covering, and success with decreasing the incidence of postoperative wound contracture, which the authors believed was necessary for the hands to heal successfully.⁴
       Fivenson et al³ reported satisfactory results using BSE in the treatment of severe mitten deformity associated with recessive dystrophic EB. They performed epidermal removal between all web spaces and fingers along with transverse and Z-plasty incisions along each finger to allow for full extension and range of motion. Meshed BSE was applied immediately to all denuded areas of the hand. After 6 months of physical therapy for the hand, the patients averaged a 55% increase in range of motion. The present study used BTM initially in attempt to obtain comparable results and then applied BSE for coverage once a healthy neodermis developed.

Figure 3

Figure 2

Figure 1

Case Reports

       Case 1. A 4-year-old boy presented with a severe case of EB-associated mitten deformity of the left hand (Figure 1). The fingertips were contracted down into the palm, and pseudosyndactyly was present between the second, third, fourth, and fifth digits. The patient had limited functional use of the contracted left hand. Contracture release was performed, and the BTM was used for skin coverage secondary to the delayed or poor healing commonly associated with EB and because there were large areas of denuded skin that prohibited harvesting a skin graft. The patient was taken to the operating room for the initial procedure. Sharp and blunt dissection was used to separate the fingertips from the palm. The pseudosyndactyly was released between the second, third, and fourth digits using sharp dissection. K-wires were then passed through the second, third, and fourth digits to prevent contracture recurrence. A significant tissue defect was created over the distal palm and palmar aspect of the distal fingers secondary to the extensive degloving associated with the contracture release (Figure 2). The defect was immediately covered with the BTM after adequate hemostasis was achieved. The BTM was secured with 4-0 chromic gut sutures, and the hand was then covered with a silver-impregnated dressing (Figure 3). Petrolatum gauze was placed around the K-wires and then wrapped with an elastic bandage (ACE^® Bandage, BD Inc., Franklin Lakes, NJ).

Figure 5

Figure 4A and 4B

       On postoperative Days 6 and 10, the patient was taken back to the operating room for dressing changes. The BTM was not infected and appeared to be healing well. It was covered with a silver-impregnated dressing soaked in antibiotic as a preventative measure. This was then covered with petrolatum gauze and an elastic bandage wrap.
       On postoperative Day 15, the patient was taken back to the operating room for removal of the BTM’s silicone layer. The BTM had excellent attachment to the areas that were previously denuded (Figures 4A and 4B). A quality neodermis was observed beneath

Figure 6 and 7

the silicone (Figure 5). The area was roughened until punctate bleeding was obtained. The neodermis was then covered with the BSE. The BSE was secured with chromic gut sutures (Figures 6 and 7). Adhesive skin closures (Steri-strips™, 3M, St. Paul, Minn), a nonadherent dressing (Adaptic™, Johnson & Johnson, Somerville, NJ), and dry gauze were then placed over the wound.
       On postoperative Days 20 and 24, the patient was taken back to the operating room for reapplication of the BTM over open areas of the wound. A total of 176 cm² of BTM was applied. Adhesive skin closures, a nonadherent dressing, and a dry dressing were again placed over the wound. The authors do not recommend frequent reapplication of BTM because the BTM cells survive at least 4 to 6 weeks on every wound and up to 6 months on EB wounds.⁵ In this case, some of the BTM was inadvertently removed in 2 areas during the dressing changes. Those areas were irrigated and a new BTM was applied.
       On postoperative Day 55, the K-wires were removed without difficulty. The patient received daily occupational therapy and wore a splint at night to prevent contracture recurrence.

Figures 8-10

       On postoperative Day 174, the patient was seen in the clinic for follow-up. A healthy epidermis was present with no signs of infection (Figures 8–10). The patient had 40 degrees range of motion of the second finger and 30 degrees with the third finger. Approximately 45 degrees of contracture was present in the fourth and fifth digit. The patient was able to achieve functional use of his thumb and index finger. Intensive physical and occupational therapy were recommended, but the patient did not closely adhere to the prescribed treatment regimen.
       Case 2. A 19-year-old man presented with EB-associated mitten deformity of the right hand. He had flexion contractures > 90 degrees in all 4 digits and thickening of the first web space. Pseudosyndactyly was present between the second, third, fourth, and fifth digits (Figures 11 and 12). The patient had extremely limited functional use of the contracted right hand.
       The patient was taken to the operating room. Each finger was released along the volar aspect, and an attempt was made to extend the fingers as much as possible. One hundred degrees of extension was achieved in the second, third, fourth, and fifth digits after the release, and K-wires were inserted to prevent contracture recurrence. A local flap was used to deepen the first web space. After performing the contracture release, a significant tissue defect was created along the volar aspect of the distal fingers as well as over the palm. The BTM was used to cover the denuded areas, as the patient did not have a sufficient amount of normal skin available to harvest a skin graft secondary to the generalized blistering due to the EB. Chromic gut sutures (size 4-0) were used to secure the BTM in place. The hand was wrapped with a silver-impregnated dressing and petrolatum gauze was placed around the K-wires. A splint was molded and placed on the hand to keep the digits extended.

Figures 13-14

Figures 11-12

       On postoperative Day 7, the patient was taken to the operating room for the first dressing change. The BTM was not infected and appeared to be healing well. Early development of a healthy neodermis with areas of punctate bleeding was present (Figures 13 and 14). The BSE was placed over the neodermis on the palm, 4 fingers, and proximal aspect of the thumb after thorough irrigation of the hand was performed. The BSE was covered with a silicone-coated polyamide dressing (Mepitel™, Mölnlycke Health Care, Gotëborg, Sweden) and wrapped with a dry dressing. An elastic bandage was used to secure the splint.
       On postoperative Day 16, the patient was taken to the operating room for a dressing change and BSE evaluation. Several areas of nonadherent BSE that were removed with the dressing were seen along the dorsal and volar surfaces of the fingers and palm. These areas were irrigated and new BSE was applied. The BSE was then covered with the silicone-coated polyamide dressing and wrapped with a dry dressing. A splint was applied and secured with an elastic bandage.

Figures 15-16

       On postoperative Day 19, the patient was taken to the operating room for a dressing change under anesthesia because he was unable to tolerate the procedure in the office. The wound was irrigated, and there was no sign of infection. The BSE was healing well (Figures 15 and 16). The hand was then covered with antibiotic ointment, petrolatum gauze, and wrapped with a dry dressing. The splint was secured with an elastic bandage.
       On postoperative Day 26, the patient was taken to the operating room for a dressing change. After irrigating the wound, excellent BSE coverage on the palm was noted, but there were still some nonadherent areas on each finger (Figure 17). The nonadherent tissue was inadvertently removed during the dressing change and new BSE was applied. The digits were then wrapped with petrolatum gauze and sterile 4 x 4 in gauze dressings were placed between the fingers. The K-wires were removed without difficulty. The hand was wrapped with dry dressings and the splint was secured.

Figure 18

Figure 17

       On postoperative Day 119, the patient was seen in the clinic for follow-up. A healthy epidermis was present with no sign of tissue breakdown or infection. The patient regained functional use of his hand and had near full range of motion in all fingers (Figure 18). He continues to receive physical and occupational therapy.

Discussion

       Surgical management of EB-associated mitten deformity presents a great therapeutic challenge. Large wounds are created in the process of separating the digits from each other, as well as the palm, during contracture release.² Several techniques have been attempted in order to provide optimal coverage and promote wound healing. A bilayered cellular matrix (Orcel™, Ortec International Inc, New York, NY) was approved by the US Food and Drug Administration (FDA) in 2001 for wound coverage following surgical release of mitten deformities. This decreased the need for autograft harvesting in these patients. Fivenson et al³ used BSE for initial wound coverage following EB-associated mitten deformity contracture release. The BSE, a living skin equivalent cultured from neonatal foreskin keratinocytes and fibroblasts, acts as a physical wound covering, stimulates rapid healing through cytokine delivery, and decreases pain. This was shown to decrease the incidence of postoperative infections and reduce the time to the start of physical therapy.³
       The BTM has been commonly used for covering partial- and full-thickness burn wounds, flap donor site coverage, pressure ulcers, chronic vascular ulcers, post-traumatic defects, and resurfacing of free flaps.^6–8 The presented cases are the first to report BTM application immediately after release of EB-associated mitten deformity of the hands caused by pseudosyndactyly.
       The BTM is an advanced wound care device comprised of a porous matrix of cross-linked bovine tendon collagen and shark glycosaminoglycan and a semi-permeable polysiloxane (silicone) layer.⁵ The semi-permeable silicone membrane controls water vapor loss, provides a flexible adherent covering for the wound surface, and adds increased tear strength. The collagen-glycosaminoglycan biodegradable matrix provides a scaffold for cellular invasion and capillary growth.⁹ The matrix eventually remodels as the cells rebuild the injured site. The porous, spongy layer is applied to the wound bed and acts a template for ingrowth of host fibroblasts and endothelial cells. Host collagen gradually replaces these cells and forms a new dermal layer—the neodermis.⁴ The BTM is available as a single-use, aseptically processed membrane system for skin replacement.
       The authors have recently treated several children with EB pseudosyndactyly deformity and found an unacceptable rate of contracture recurrence when using BSE alone. The BTM was used in an attempt to decrease the severity of contracture recurrence. In addition to its excellent tensile strength, BTM has been successful in decreasing the incidence of postoperative wound contracture. The results were much better when BTM was used prior to BSE application than when BSE was used alone.
       The patients presented here had significant hand contracture with limited functional use secondary to pseudosyndactyly. Once the contracture and pseudosyndactyly were released, significant tissue defects were created over the palmar aspect of the proximal fingers and palm. Skin grafting was not an option because the patients did not have healthy donor sites available secondary to extensive skin denudation as a result of the EB. For this reason, the BSE was applied to the neodermis after the silicone layer was removed as opposed to using an autogenous split-thickness skin graft.
       The decision to remove the silicone layer of the BTM on Day 15 in Case 1 was based on data from Stern et al¹⁰ that showed vascularization of the entire BTM matrix is complete 14 days after the initial application. Another benefit of the BTM is that it substantially minimizes long-term postoperative contracture, which was essential for the patient in this case to regain functional hand use.⁴ The silicone-coated polyamide dressing, which adheres to dry skin but not to moist grafts or wounds, was able to fix and protect the inner BTM matrix and did not cause maceration or damage to the BTM during dressing changes as reported in Case 2. The porous structure permits wound exudate to pass directly into the dressing.¹¹
       After 4 months, both patients’ wounds were completely healed and had intact and viable epidermis. Both patients continue to receive physical and occupational therapy to improve their range of motion and functional hand use. The authors will continue to closely follow how these patients progress with their rehabilitation.
       The surgeon must consider several potential pitfalls while performing this procedure. First, while performing the pseudosyndactyly contracture release, it is crucial to preserve the palmar and digital neurovascular bundles. This is essential for adequate wound healing as well as maintaining postoperative sensation in the hand, which is necessary to regain full functional use. Also, complete degloving of the hand during contracture release is not recommended as this significantly prolongs wound healing in patients with EB. Proper pin positioning is essential to achieve a satisfactory outcome. Fluoroscopic imaging is recommended to ensure adequate pin placement and to avoid malpositioning, which can result in unsatisfactory results and erosion through the skin.