Serial Application of Meshed Collagen-chondroitin Silicone Bilayer Matrix to Obtain Full Coverage over Bone and Tendon in Challenging Situations and Medically Compromised Patients: A Small Case Series

Soft tissue defects caused by trauma and other diseases in medically compromised patients present significant challenges to the reconstructive surgeon, particularly when tendon, bone, cartilage, or other vital structures are exposed. Skin grafting is a widely used technique, but it cannot cover exposed denuded tendon, bone, or cartilage, and it can result in poor cosmesis.¹ Random pattern local and regional flaps cover bony surfaces and tendons, but their use is limited by the size and location of the defect.² Pedicled and free flaps allow coverage of large tissue defects, but they are sometimes associated with substantial donor site morbidity, and not all patients are candidates for such treatment.² Currently, dermal matrices are widely used in reconstructive and plastic surgery, and these products offer new opportunities for wound coverage.^3,4

Integra Meshed Bilayer Wound Matrix (MBWM; Integra LifeSciences, Princeton, NJ) and PriMatrix (FBADM; Integra LifeSciences, Princeton, NJ) are xenogeneic ADMs^5,6 that are derived, respectively, from adult bovine Achilles tendon and fetal bovine dermis. They are available in different constructs: bilayer (MBWM) and single layer (FBADM).^7,8 MBWM is a bioengineered collagen matrix, whereas FBADM is a decellularized collagen matrix. MBWM is composed of a layer of cross-linked bovine tendon type I collagen and chondroitin-6-sulfate (derived from shark cartilage), and a silicone layer.⁷ FBADM is composed primarily of type I and type III collagen; type III collagen is associated with healing and developing tissues.⁸ MBWM is applied to a wound in a 2-stage procedure.⁹ First, the wound is excised and debrided, and the dermal matrix is placed over the wound bed. Second, after 3 to 4 weeks, when neovascularization is achieved and the neodermis is being formed, the silicone layer is removed and replaced by an STSG.^10,11 MBWM is also applied in a 1-stage procedure, after neovascularization is achieved and the neodermis is forming, the silicone layer is removed and the wound is left to heal by secondary intention (ie, reepithelialization).^12,13 FBADM is applied to the wound as a single-layer product. Meshed variants—that is, MBWM and FBADM—are frequently used in combination
with NPWT.

Historically, MBWM, FBADM, and their variants have been used in the management of a broad range of wounds, including burns, acute and chronic wounds, cancer resection, and Mohs skin cancer.^14-29 MBWM and FBADM have been used to manage particularly challenging wounds with exposed bone and tendon to create a vascularized surface.^17,30-32 Such application is important because exposed bone, tendon, or cartilage do not have sufficient vascularity to support a granulation bed for reepithelialization or neovascularization for skin graft survival.¹

The present case series discusses 5 adult patients with a variety of competing and challenging medical problems whose wounds were managed using MBWM and in some cases involved the serial application of dermal matrices (eg, FBADM or MBWM) over exposed structures. These ADMs allow coverage of wounds with exposed bone and tendon in compromised patients and offer alternatives in cases in which early vascularized tissue coverage is not a good option.

The study was conducted following the principles outlined in the Declaration of Helsinki. All patients were informed of the pros and cons of the management of wounds with MBWM and/or FBADM, and all patients signed a consent form approving or rejecting such information. All patients gave informed written consent for the use of the data collected, including the publication of photographs. The wounds of the 5 patients were reconstructed with the ADMs at 2 community hospitals: Community Hospital of the Monterey Peninsula, Monterey, California, and Salinas Valley Memorial Hospital, Salinas, California.

Case 1

A 44-year-old male patient was involved in a motor vehicle accident and was admitted to the hospital. He presented with a significant degloving of the scalp down to the calvarium, with exposed bone and involving most of the upper central scalp (Figure 1A). The patient was an active 1 pack per day smoker who continued to smoke during the entire treatment course. He had well-controlled HIV infection, was extremely thin, and had anorexia. The wound was not infected. The patient did not receive antibiotic treatment (eg, intravenous) other than prophylactic antibiotic postoperatively. One major surgical debridement procedure was performed on the wound after the accident. The resulting defect measured 10 cm × 6 cm (Figure 1B). MBWM was applied to the wound in an outpatient procedure in the OR under general anesthesia, in combination with NPWT (KCI, St. Paul, MN). The sheet of dermal matrix was affixed peripherally with chromic suture (Figure 1C), with the NPWT device used to hold it in place over the exposed bone, followed by application of the device with the black sponge directly over the ADM. The NPWT device was set to −75 mm Hg low continuous negative pressure and left in place for 3 weeks, with NPWT dressing changes every 3 days.

The patient was discharged after placement of the dermal matrix. Vascularization of the dermal matrix was achieved 3 weeks after placement (Figure 1D), at which time the outer silicone layer was removed in the clinic under topical anesthesia. The incorporation rate of the dermal matrix to the wound bed was 100%. The wound was allowed to close by secondary intention, with a goal of reconstruction with local fasciocutaneous flap, facilitated by scar contraction. Reepithelialization occurred over the next 2 months (Figure 1E, 1F). The patient returned to the hospital 8 months after the accident for final scalp reconstruction with a local fasciocutaneous flap, and an excellent result was achieved (Figure 1G). The wound was debrided of scar tissue and covered with autologous fasciocutaneous flaps. No infection, necrosis, or other postoperative complications were noted. After reconstructive surgery of the scalp the patient’s hairline appeared near normal, with excellent cosmesis and no functional issues 8 months after the initial injury (Figure 1H).

Case 2

A 62-year-old female patient was admitted to the hospital and presented with a giant neglected squamous cell carcinoma of the posterior scalp (Figure 2A). Magnetic resonance imaging did not indicate bony involvement. The patient had no major comorbidities. She was transferred to the OR and underwent resection of the involved tumor, resulting in a defect comprising the entire occipital skull down to the calvarium, with loss of periosteum (Figure 2B). A neurosurgeon recommended against burring off the outer table and performing STSG. A latissimus flap, skin graft (on the flap), and scalp flaps were performed in an attempt to achieve coverage. The latissimus flap was unsuccessful. The flap was removed 2 weeks later, and the area was debrided. The resulting defect measured 10 cm × 12 cm. Subsequently during this complex hospitalization, MBWM was applied to the wound as an inpatient procedure in the OR under general anesthesia (Figure 2C), in combination with NPWT. The sheet of dermal matrix was secured around the edges with staples and centrally with 4-0 chromic quilting sutures, followed by application of NPWT with the black sponge directly over the ADM. The NPWT device was set to −125 mm Hg low continuous negative pressure and left in place for 3 weeks, with NPWT dressing changes every 3 days. Partial vascularization of the dermal matrix was achieved 3 weeks after placement, at which time the outer silicone layer was removed in the clinic under topical anesthesia. The incorporation rate of the dermal matrix to the wound bed was 75%. NPWT was reinstituted over the wound after removal of the outer silicone layer.

Three weeks later, the patient was returned to the OR for an inpatient procedure. Under general anesthesia, scalp flaps were readvanced, closing only a portion of the wound, with skin grafting performed over the remainder (ie, area of the wound where MBWM incorporated). The area of the wound where MBWM did not incorporate was debrided and managed with meshed FBADM; this occurred 3 weeks after removal of the outer silicone layer of MBWM and 6 weeks after the initial placement of MBWM. The sheet of dermal matrix was sutured to the wound base with 4-0 chromic sutures, and a standard bolster was applied. NPWT was reinstituted over the wound. Partial vascularization of FBADM was achieved 3 weeks after placement, at which time the incorporation rate of the dermal matrix to the wound bed was 50%. The skin graft took well over the areas where the MBWM had incorporated, but the remainder of the wound was exceptionally slow to heal (Figure 2D, 2E). Further closure of portions of the wound was achieved with a secondary scalp fasciocutaneous flap. Free flap surgery was offered, but the patient declined, preferring not to undergo additional major surgeries. She was treated with local wound care for the next 10 months. Healing was prolonged, but complete healing was achieved, with the exception of a 2 cm² area of the larger wound (Figure 2F). This area was ultimately closed with debridement of the skull and STSG (150 µm thickness) (Figure 2G). Total time to healing was 1 year after placement of the first ADM (ie, MBWM). Stable soft tissue coverage and successful reconstruction were achieved (Figure 2H). No infections, necrosis, or other postoperative complications were noted. The patient was monitored for 1 year, and there was no cancer recurrence at that time. The patient obtained stable healing after undergoing reconstructive surgery of the posterior scalp. She wore her hair long, which provided good coverage of the defect; she was satisfied with the clinical outcome.

Case 3

An 89-year-old female patient was admitted to the hospital for a necrotizing infection of the left lower limb. She had venous stasis and congestive heart failure on admission. Following surgical debridement, the patient had an open wound with wide exposure of the tibialis anterior (Figure 3A). The resulting defect measured 10 cm × 3 cm. A vascular surgeon recommended below-knee amputation, but the patient wished to undergo all attempts at limb salvage. MBWM was applied to the wound as an outpatient procedure in the OR under monitored anesthesia care, in combination with NPWT. The sheet of dermal matrix was secured around the edges with staples and centrally with 4-0 chromic quilting sutures (Figure 3B), followed by application of the NPWT device with the black sponge directly over the ADM. The NPWT device was set to −75 mm Hg low continuous negative pressure and left in place for 3 weeks, with NPWT dressing changes every 3 days. The patient was discharged after placement of the dermal matrix. Partial vascularization of the dermal matrix was achieved 3 weeks after placement, at which time the silicone layer was removed in the clinic under topical anesthesia (Figure 3C). The incorporation rate of dermal matrix to the wound bed was 90%.

Owing to a series of other health problems and setbacks, including recurrent episodic congestive heart failure exacerbations with recurrent wound breakdown, skin grafting of the wound area was not performed. Instead, the wound was allowed to close by secondary intention. Reepithelialization ultimately occurred over the next 16 months after dermal matrix placement, after the patient’s cardiac status was stabilized and diuresis performed (Figure 3D). The size of the wound fluctuated as the patient’s heart failure waxed and waned, ranging from as small as 1 cm × 1 cm to as large as 4 cm × 3 cm during that time. A variety of dressings were used in an attempt to manage the patient’s wounds. For example, owing to a challenging combination of arterial and venous insufficiency the patient was unable to tolerate anything more than a single-layer compression stocking. Absorptive topical antimicrobial dressings were used, such as silver alginate. As of the time of this writing, the patient had achieved stable healing of the area (Figure 3E). No infections, necrosis, or other postoperative complications were noted. The patient maintained ambulation during the entire treatment course and retained her independence and function as of the time of this writing, 1 year after treatment.

Case 4

A 46-year-old male patient presented to the emergency room with a complex necrotizing infection of the right lower limb. He was an active one-half pack per day smoker and had neglected diabetes with a hemoglobin A_1C level of 10.5% on admission. He stopped smoking and became compliant with diabetic care during the treatment course. Following surgical debridement and owing to the infection, the entire soleus muscle and the lateral one half of the gastrocnemius muscle were lost, resulting in an open wound with a large section of exposed tibia (Figure 4A). The resulting defect measured 18 cm × 11 cm. MBWM was applied to the wound as an outpatient procedure in the OR under general anesthesia, in combination with NPWT. The sheet of dermal matrix was secured around the edges with staples and centrally with 4-0 chromic quilting sutures (Figure 4B), followed by application of the NPWT device with the black sponge directly over the ADM. The NPWT device was set to −125 mm Hg low continuous negative pressure and left in place for 3 weeks, with NPWT dressing changes every 3 days. The patient was discharged after placement of the dermal matrix. Partial vascularization of the dermal matrix was achieved 3 weeks after placement (Figure 4C), at which time the outer silicone layer was removed in the clinic under topical anesthesia. The incorporation rate of dermal matrix to the wound bed was 90%.

A second application of MBWM was performed over the wound after debridement, as an outpatient procedure in the OR under general anesthesia (following the removal of the outer silicone layer of the first application of MBWM, 3 weeks after the initial placement of MBWM) in an effort to achieve 100% incorporation of dermal matrix to the wound bed prior to skin grafting. The sheet of dermal matrix was secured around the edges with staples and centrally with 4-0 chromic quilting sutures, followed by application of the NPWT device with the black sponge directly over the ADM. The NPWT device was applied and set to −125 mm Hg low continuous negative pressure and left in place for 3 weeks, with NPWT dressing changes every 3 days. The patient was discharged after placement of the dermal matrix. Vascularization of the second dermal matrix was achieved 3 weeks after placement, and the incorporation rate of the matrix to the wound bed was 100%. After removal of the silicone layer, an STSG (150 µm thickness) was placed in the OR in combination with NPWT (Figure 4D). The patient was discharged after STSG. Skin autograft take was 100% after 4 weeks. The patient developed a more distal infection, adjacent to the wound, 1 month later. He was treated with additional debridement, a course of NPWT, and another skin graft. Wound healing was achieved 2 months after the initial surgery (Figure 4E). No necrosis or other postoperative complications were noted. Stable soft tissue coverage was obtained, and the patient was able to ambulate normally at the conclusion of wound management, 5 months after the first dermal matrix placement.

Case 5

A 38-year-old male patient sustained a severe crush injury of the left forearm following a ground level fall. He presented to the emergency room with a heavily contaminated open comminuted fracture, absent radial pulse, and a tourniquet that had been inflated in the field owing to severe bleeding. The patient had hypertension. He underwent 4 surgical debridement procedures over 2 weeks, as well as open reduction and internal fixation with placement of a reconstruction plate on the radius and another on the ulna. Compartment release and carpal tunnel release repair of the radial arteries were performed, along with a saphenous vein graft repair of multiple tendons, followed by placement of an NPWT device to manage the open wound. Exposure of the radial reconstruction plate required some muscle flap rearrangement and extensive muscle debridement. Advancement of a forearm muscle flap was successful in obtaining soft tissue coverage over the reconstruction plate, and the patient was left with an open wound with a granulating base and without exposed hardware or bone, but with exposure of multiple tendons. The resulting defect measured 12 cm × 22 cm (Figure 5A). MBWM was applied to the wound as an outpatient procedure in the OR under general anesthesia, in combination with NPWT. A sheet of dermal matrix 10 cm × 25 cm in size was secured around the edges with staples and centrally with 4-0 chromic quilting sutures (Figure 5B), followed by application of the NPWT device with the black sponge directly over the ADM. The NPWT device was set to −75 mm Hg low continuous negative pressure and left in place for 3 weeks, with NPWT dressing changes every 3 days. The underlying vein graft was buried and was never exposed, which permitted continuous NPWT. The patient was discharged after placement of the dermal matrix.

Vascularization of the dermal matrix was achieved 3 weeks after placement, at which time the outer silicone layer was removed in the clinic under topical anesthesia. The incorporation rate of dermal matrix to the wound bed was 100%. By that time the swelling from the compartment syndrome had diminished substantially, and the final wound site measured 10 cm × 6 cm (Figure 5C). After removal of the silicone layer, an STSG (150 µ m thickness, meshed 1:1) was settled in the OR in combination with NPWT. NPWT was discontinued 1 week after placement of the skin graft, and the wound was managed with standard dressings thereafter. Postoperatively, the patient developed shingles while still in the hospital and required a high-dose steroid taper of several weeks’ duration. Wound healing was achieved 4 weeks after STSG placement, and skin autograft take was 100% (Figure 5D). No infections, necrosis, or other postoperative complications were noted. This case shows the successful use of dermal matrix to achieve soft tissue coverage of a large wound with exposed structures (including tendons) over a reconstruction plate.

The present study reports a case series of 5 adult patients whose wounds were managed with MBWM for soft tissue defects, over exposed structures, in challenging situations, and in medically compromised states. In some cases, the reconstructive surgeries involved multiple procedures, including the serial application of a dermal matrix (FBADM or MBWM). Although for a variety of reasons the 5 patients were poor candidates for immediate coverage using skin grafting or microvascular free tissue transfer, complete soft tissue coverage of their wounds was ultimately obtained using the ADMs.

The 5 patients (age range, 38 years–89 years) in this study had comorbidities including heavy smoking, HIV infection, malnutrition, venous stasis, congestive heart failure, and untreated diabetes (Table 1). Despite the challenging and medically compromised patient situations, stable wound coverage and successful reconstruction were achieved. In all 5 patients, the use of MBWM and the serial use of dermal matrices (patients 2 and 4) resulted in satisfactory cosmesis and functional outcomes. The hairline was restored in patient 1, stable soft tissue coverage was achieved in patient 2, functional lower limb salvage was achieved in patients 3 and 4, and stable soft tissue coverage of a large wound with exposed tendons and over a reconstruction plate was achieved in patient 5. These results highlight the potential of MBWM and the potential of serial application of dermal matrices to provide an environment that supports wound healing in challenging situations and medically compromised patients.

In patient 1, a free flap was not used because it would have resulted in poor cosmesis and because the patient was an active smoker. In patient 2, the latissimus flap was unsuccessful. Patient 3 was not a good surgical candidate for any major flap repair owing to extensive trauma. Patient 4 was a poor candidate for free flap surgery owing to uncontrolled diabetes; additionally, the local flaps that would have been used for bony coverage had been sacrificed owing to the infection. The complexity in case 5 arose from the extent of the wound and the number of exposed structures (especially tendons) and the urgency of trying to achieve wound coverage over a reconstruction plate. In patients 1, 3, and 5 successful wound closure was obtained using a single application of MBWM, whereas in patients 2 and 4 successful wound closure was achieved using serial application of MBWM and either FBADM (patient 2) or MBWM (patient 4). The results in this case series highlight the potential of MBWM, as well as serial application of MBWM with FBADM or MBWM, in reconstructive and plastic surgery (particularly over exposed structures) when skin graft and microvascular free tissue transfer are not valid options.^1,2

The use of ADMs in wound reconstruction often involves 2-stage reconstruction. MBWM is applied to the excised wound, and after 3 to 4 weeks, when neovascularization is achieved and the neodermis is being formed, the silicone layer is replaced with an STSG.⁹ Two-stage procedures are generally used in patients with large defects who would benefit from a secondary skin graft to complete wound closure.^9,11 Single-stage procedures, through reepithelialization, offer the opportunity to avoid multiple surgeries and reduce donor site morbidity.^12,13 In the 5 cases reported in the present study, the outer silicone layer was removed 3 weeks postoperatively in the clinical setting. In patients 1, 2, and 3 the wounds were allowed to close by secondary intention, with a goal of reconstruction with local fasciocutaneous flap, facilitated by scar contraction (patient 1), and scalp flaps were readvanced closing only a minority of the wound and the remainder skin grafted in (patient 2), whereas an STSG was placed in patients 4 and 5. In patient 5, a sheet of MBWM was placed over an underlying vein graft that was buried, over a reconstruction plate, and over exposed flexor tendon. The results reported in the present study further highlight the capacity and capability of MBWM to provide reconstructive solutions in challenging situations and medically compromised patients, using different management modalities, similar to findings previously published by Shah and Taupin.³²

The serial stacking of MBWMs has been reported to address deep defects of the palmar surface of the hand, leading to excellent wound healing and coverage as well as full range of motion.³³ In the present study, the serial application of MBWM resulted in full wound coverage, including over bone and tendon, in challenging situations and medically compromised patients. The incorporation rate of dermal matrix to the wound bed was 100% in patients 1 and 5, 75% in patient 2, and 90% in patients 3 and 4 (Table 2). Patients 2 and 4 received a second application of dermal matrix to obtain full wound coverage. In patient 2, meshed FBADM was used in the area of the wound where the initial application of MBWM did not incorporate to the wound bed, whereas patient 4 received a second application of MBWM to achieve 100% incorporation of dermal matrix to the wound bed. In those patients, the incorporation of dermal matrix to the wound bed was assessed when the color of the dermal matrix had progressed from pink through pale yellow and finally to peach, revealing a well-vascularized neodermis.¹¹ In patient 2, the second application of dermal matrix was performed 3 weeks after removal of the outer silicone layer of the MBWM (6 weeks after the initial placement of MBWM), whereas in patient 4 the second application of dermal matrix was performed early after removal of the outer silicone layer of the MBWM (3 weeks after the initial placement of MBWM).

One lesson learned from case 2, and subsequently implemented in case 4, is that the serial application of MBWM should be performed early on when the initial MBWM partially incorporates to the wound bed; doing so greatly decreases time to healing. It could be theorized that early serial application of MBWM in patients 2 and 3 to achieve 100% incorporation of dermal matrix to the wound bed (as in patient 4) may have improved time to healing in those patients. In cases of incomplete coverage, early serial application of MBWM may lead to faster recovery time.

This case series has limitations. There are also limitations to the use of dermal matrices (eg, MBWM) and to the serial application of MBWM and dermal matrices for the management of wounds, particularly in medically compromised patients and over exposed structures. This study has a limited number and diverse set of cases. Additionally, this is a short-term study. The advantages, disadvantages, benefits, and limitations of using dermal matrices for wound reconstruction must be weighed against other procedures. Deciding which management option to use depends on the final result, reconstruction quality, and functionality desired, as well as on patient factors.^3-6 The use of dermal matrices has a learning curve for the surgeon. Whether to use staged or non-staged procedures must be considered when using dermal matrices. Infection, hematoma, or seroma may occur postoperatively. There are contraindications for using dermal matrices for wound reconstruction (eg, sensitivity to bovine collagen or chondroitin materials). The cost of using dermal matrices should be balanced against the associated costs of alternative procedures and patient’s outcomes. Further studies are needed to evaluate the benefits of the serial application of MBWM and dermal matrices in the context of reconstructive surgery.

This case series reports the successful single and serial use of MBWM for the management of wounds with exposed vital structures, in challenging situations and in medically compromised patients. This small case series explored the clinical utility of the serial application of MBWM to obtain full coverage over bone and tendon in this patient population. In wounds with incomplete coverage, the serial application of MBWM may lead to faster recovery time for the patient. Further study and evaluation of the clinical benefits of the serial application of MBWM and dermal matrices are warranted.