Limb Salvage Using Human Placental Allografts: Adding to the Reconstructive Ladder Paradigm

Human placental allografts are the latest treatment modalities for diabetic ulcers, chronic wounds, limbs, and tendons for healing cascade and promot-ing granulation tissue coverage. Purion ® processed dehydrated human am-nion/chorion membrane allografts (dHACM), decellularized human collagen matrix (dHCM), dehydrated umbilical cord (dHUC) and micronized dehydrated human amnion/chorion membrane allografts (mdHACM) have been the newest modality used to salvage injured human extremities with tendon and bone exposure. A 53-year-old male was assaulted and sustained second and third degree burns to both legs. The left extremity had a 9.5% total body surface area (%TBSA) burned. The right extremity had a 5.5% TBSA and three exposed tendons (Achilles/flexor digitorum longus/tibialis anterior), muscles, talar and tibial bones. Bilateral extremity pedal pulses were present, and all toes had less than two second capillary cental allografts prevented the need for myocutaneous flap coverage or amputation of the right foot.

In vitro, these factors have been shown to stimulate tissue growth, regeneration, stem cell migration in animal models, fibroblast proliferation, and decreased inflammation [6] [7] [8] [9]. In 2017, Glat and Davenport recommended that placental allografts become adjuvant therapy in the surgical Reconstructive Ladder Paradigm for limb salvage [12]. Wound closure and limb salvage were successful with the combined application of dHCM, and dHACM, except for occasional difficulties with injured tendon and bone [11]. This case report illustrates successful limb salvage and full tendon/bone coverage with granulation tissue through the addition of dHUC allograft and mdHACM injections into the tendons. Placental allograft applications are described for limb reconstruction without the use of free tissue or rotational flaps.

Case Report
Our patient was a Hispanic man with a past medical history of gout and obesity (BMI 32 kg/m 2 ). He lived at home with his family (Table 1). While bicycling outside his home, he was assaulted with a Molotov cocktail and sustained second and third degree burns to both lower extremities. The left leg had a 9.5% total burn surface area (%TBSA) and the right leg had a 5.5% TBSA (Figure 1). Muscles, tendons (tibialis anterior, flexor digitorum longus, Achilles), talar and tibial Co-morbidities Gout Figure 1. Second and third degree burn injuries; after initial debridement; and twenty-two weeks after initial injury. bones were exposed on the right lower extremity. On initial exam, bilateral pedal pulses were present, and all toes had less than two second capillary refill. Sensation, motor, and strength were normal. During the 48-day-hospital stay, the patient had eight operations. There were weekly tangential excisional debridements of necrotic tissue with weekly application of one or more of the following placental allografts: dHACM, dHCM ( Figure 2), dHUC ( Figure 3), or mdHACM ( Figure 4). The dHACM, dHCM and dHUC were used initially on both legs (week 2), then only on the right ankle (weeks 3 -6). In addition, mdHACM was injected into the three exposed tendons of the right foot (weeks 4 -5). When a wound infection needed to be treated, a combination of intravenous antibiotics and a topical antispetic wash such as hypochlorous acid (Vashe Wound Solution, UMNA, Fort Worth, Texas) was used. Table 2 shows the usage protocol for the different placental allografts. Table 3 provides the features and application of each placental allograft product. Before each application of the placental allografts, exposed talar or tibial bone was tangentially trephined (top layer of bone was removed using a large "pineapple" drill bit in a hand-held burring device, to expose bone arteriolar bleeding. Normal saline prevented frictional heat with the burring. The exposed tendons were trimmed superficially with scissors to remove any desiccated tissue. Then, dHACM, Surgical Science     The product is like cellophane: semi-transparent, either light tan or orange, flexible and can be easily cut to fit an atypical wound size.
Cut to fit over the wound bed and apply without getting the product wet. Can be fenestrated by a scalpel & applied directly over the dHCM. The product is placed in such a way that the written embossed word on the product reads "Up".

23,110 dHUC *EPICORD ®
It is brittle in its dehydrated form and requires rehydration for approximately ten seconds in a 20 mL normal saline bath. Once rehydrated, it can be meshed using a 2:1 split thickness graft mesher.
Applied directly over the trephined bone. It can be cut to fit the desired area after rehydration of the product.

28,707
mdHACM This solution can be injected into exposed tendon, muscle, or subcutaneous tissue. The volume used is left to the discretion of the authorized medical professional. Because the reconstituted material is viscous, proper pre-injection techniques reduce possible air introduction. With time elapse, product separates between rehydration and administration: re-suspend by shaking within 12 hours of reconstitution.
Transfer the recommended volume of 0.9% sterile saline into the vial. With a back-and-forth motion, transfer with the plunger, and mix the particulate to create a full suspension in the syringe. dHUC or dHCM was applied directly over the freshly trephined bone and the tendons. In addition, mdHACM was also injected into the tendons. Wound sur-faces were covered with dressings made of petroleum gauze slathered with a hydrophilic ointment ( Figure 5) followed by application of negative pressure wound therapy to bolster and promote healing ( Figure 6). During the hospitalization, the patient underwent physical therapy to maintain strength and mobility in his feet and legs. At discharge for rehabilitation, 90% of the graft was viable over the right ankle joint, tendons and bone (Figure 1).

Discussion
The incorporation of four placental allografts (dHCM, dHACM, dHUC, and mdHACM) into this current limb salvage protocol preserved the extremity at risk for more invasive procedures-either a myocutaneous flap or amputation.  Specifically, the addition of dHUC over the bone and mdHACM injections into tendons created an environment for adequate granulation tissue growth to receive and sustain STSG coverage and wound closure. It has been postulated, along with our own past anecdotal clinical experience, that granulation tissue growth over inflamed or scarred tendons is difficult to generate. However, injections of mdHACM successfully supported tendon preservation and granulation tissue growth in this case [13]. A report about a viable, intact, and cryopreserved placental membrane (vCPM) (Grafix, Osiris Therapeutics, Columbia, MD) noted that seven (58%) patients of twelve had successful wound closure with tendon exposure (size 17.5, range 4 -49 cm 2 ) attached to or over a joint with an average eight (range 3 -13 cm 2 ) allograft applications [14]. The current patient had an acute burn injury with a much larger area of involvement (3100 cm 2 ).
Ang and Chih-Kang have noted that placental membrane allografts aid in the "… normal healing cascade of hemostasis, inflammation, proliferation, and remodeling, … because tendon regeneration occurs through three main phases: inflammation, proliferation, and remodeling …" [15]. Fibroblast-induced scarring of the injured tendons can be reduced by placental membranes, because they contain hyaluronic acid, which dampens the upregulation of the biomarker, transforming growth factor-β (TGF-β), which triggers fibroblasts to undergo a phenotypical change to become myofibroblasts and contribute to the scarring and fibrosis during healing [15].

Conclusion
In conclusion, the use of human placental allografts removed the necessity for myocutaneous flap coverage or an amputation of the right foot in this patient. mdHACM and dHUC were useful in covering the tendons with granulation tissue to form a bed for STSG coverage and adherence. A combination of placental allografts used to cover the wounds, deep tissue structures, and injectable products had a favorable impact in this patient's limb salvage outcome ( Figure 1). By avoidance of the physical, financial, and psychological burdens associated with more invasive procedures typically considered in the standard reconstructive ladder, a vital quality of life (limb retention) was also achieved for the patient [11] [12].

Conflicts of Interest
There are no other conflicts of interest to declare.