Key Insights On Split-Thickness Skin Grafts
The goal of soft tissue coverage is to restore form and function. However, due to the anatomic complexity of the foot and ankle, soft tissue coverage in this area often falls short of Sir Harold Gillies’ adage to “… replace like with like.”1,2 Ideally, soft tissue coverage of the foot and ankle would involve primary repair free of tension and utilize neighboring sensate native tissue that is capable of withstanding the forces sustained during gait.1-3 Soft tissue wound coverage employs various forms of conservative and surgical techniques aimed at creating rapid, durable and functional closure using the simplest and least invasive techniques.4-9 Delayed primary closure, skin grafting, local, pedicle or free tissue transfer are some of the surgical tools that one may employ in his or her armamentarium.8,9 Whether it is the result of a severe infection or aggressive surgical debridement, extensive soft tissue loss should not be a major concern as properly performed skin grafting, local flaps, muscle flaps and distant pedicle flaps represent viable and cost-effective means of providing early and durable soft tissue coverage of diabetic foot and ankle wounds. How To Ensure Adequate Preparation Of The Recipient Site In order to achieve successful outcomes with skin grafting procedures, one must properly prepare the recipient site to accept soft tissue coverage. First and foremost, clinicians must ensure that the patient’s medical comorbidities have been fully addressed prior to attempting soft tissue wound coverage.10-12 Infected diabetic ulcers with osteomyelitis can be a major source of disability and morbidity. When it comes to severe diabetic foot infections, one should consider aggressive surgical debridement, vascular reconstruction when indicated, antibiotic therapy, adjunctive local wound care and appropriate offloading. Paramount to the successful treatment of diabetic foot infections is a well educated and compliant patient. In this regard, it is important to view the patient as a complete individual and not simply a wound. Clinicians should emphasize proper and ongoing patient and family education.13-15 Regarding debridement, one must completely remove all necrotic and infected soft tissue and/or bone from the wound initially, converting the defect to a surgically clean acute wound.11,16-23 Clinicians should obtain intraoperative cultures of the deepest exposed soft tissues and/or bone in order to facilitate more reliable identification of the causative microorganisms. Researchers have shown that using a power irrigation system or “high-pressure pulsatile lavage” is more effective than using a handheld bulb-syringe lavage during surgery.24,25 However, surgeons should employ caution with these devices since several studies have demonstrated increased edema within the already traumatized soft tissues, seeding of bacteria deeper within the wound interstices, and extensive aerosolization throughout the operating room.19-21,25-27 In this regard, some authors have found it helpful to place the lower extremity inside of an X-ray cassette cover or “extra” Mayo-stand cover during irrigation in order to avoid inadvertently spraying operating room personnel and to limit aerosolizing the irrigation fluid.27 When vascular status is intact, one should consider primary wound closure for the surgically clean wounds based upon the aforementioned principles for wound closure. In regard to those wounds that are deemed contaminated but clean or are too large for primary closure, surgeons should pack these open initially and close by secondary intention or delayed primary closure. One may use negative pressure wound therapy (NPWT) to optimize the wound bed, allowing for more timely and less invasive wound closure techniques.13,15 An Overview Of Skin Grafting Procedures Skin grafting is the workhorse of wound closure due to the fact that it is simple to perform, reliable, minimally invasive and cost-effective. One may repeat this procedure as necessary in order to facilitate full soft tissue wound coverage. When it comes to skin grafts, surgeons should consider their application to clean surgical wounds free from any necrotic or infected tissue. The skin grafts will fail if the recipient site is draining, actively bleeding or grossly infected. In the diabetic foot, one should use skin grafts in non-weightbearing areas and for coverage of donor sites of locally based flaps. Surgeons may harvest these grafts as either split-thickness skin grafts (STSGs), full-thickness skin grafts (FTSGs) or pinch grafts (PGs).28-30 Split-thickness skin grafts consist of the epidermis and a portion of the dermis.28,29 Depending on the needs of the patient, one may harvest thin grafts (i.e., 0.005 to 0.012 inches), medium grafts (i.e., 0.012 to 0.018 inches) or thick grafts (i.e., 0.018 to 0.030 inches). These thicknesses vary only in the amount of dermis that one includes.28,29 While STSGs are most commonly harvested from the lateral thigh, medial non-weightbearing arch of the foot, posterior-medial calf or posterior-lateral calf of either lower extremity, we prefer to harvest them from the ipsilateral extremity since it is already exposed and sterile. The donor sites heal easily and are harvested under local anesthesia with epinephrine. Full-thickness skin grafts consist of the entire thickness of the epidermis and dermis.28,29 They are most commonly harvested from redundant soft tissue folds about the lateral hindfoot and from the dorsal intermetatarsal spaces where one is afforded direct, tension-free closure.31,32 However, the close proximity to the cutaneous nerves is of concern so one should take great care to identify, protect and retract these structures during harvest.31-33 Other sites include the flexor surfaces of joints and the inguinal creases. Pinch grafts consist of irregular segments of the epidermis and dermis harvested as a small cone of tissue.34 Although pinch grafts are rarely used, surgeons most commonly harvested these grafts from the medial arch or lateral hindfoot regions of the foot.31,35,36 However, one may obtain these grafts from just about any location along the entire lower leg. Harvesting The STSG: What You Should Know When harvesting the STSG from the foot, one would use a regional field infiltrative anesthesia block and intravenous sedation. When the STSG is harvested from the calf or thigh region, the surgeon would perform the procedure with the patient under spinal or general anesthesia.33,37,38 Surgeons commonly use a power air-driven dermatome (Zimmer), which is set between 0.0016 and 0.018 inches. The surgical assistant applies a tongue depressor or moistened gauze sponge both behind and in front of the power dermatome as it is advancing since they function more efficiently on a flat surface under tension.32,33 One would then proceed to fenestrate the harvested graft manually with repeated passes of a surgical scalpel (i.e., “pie crusting”) or mesh it at a ratio of 1:1.5 or greater using a commercially available mesher.33,39 (Surgeons can save any unused skin in a saline-soaked gauze sponge and refrigerate it for up to 21 days. If any graft failure occurs, one can reapply this unused skin for the patient as long as one has properly addressed the reason for failure.33,40) One should add a non-adherent or occlusive dressing to the harvest site and proceed to apply an absorptive gauze pad, and either a compression wrap or foam-type tape. How To Apply The STSG To The Recipient Wound Site Once the skin graft is harvested, the surgeon should apply it to the recipient site as expeditiously as possible. The recipient site should be free of any active bleeding in order to avoid hematoma or seroma formation between the skin graft and underlying recipient bed, which would prohibit fibrin anchorage and subsequent vascular in-growth.28,29,41-43 The surgeon would proceed to apply a bolster dressing in order to firmly secure the STSG in place. A number of elaborate bolster dressings have been described in the literature.28,29,44-46 However, if the wound recipient site does not possess variable depth and irregularity, the authors prefer to use either a simple surgical glove or a non-adherent dressing cover, which one can staple around the perimeter of the wound and the wound itself over saline-soaked cotton balls or gauze sponges. This provides an inexpensive, simple and effective bolster dressing alternative.47,48 If the wound is not of uniform depth or is highly irregular, researchers have shown that using topical negative pressure wound therapy (VAC therapy, KCI) can serve as an effective bolster. Using VAC therapy also provides the added benefits of improved exudate removal, promotion of vascular ingrowth and prevention of shearing forces about the graft application site.49,50 Inosculation of skin grafts by vascular buds usually begins by the fifth postoperative day. It is important to avoid changing the dressings the first postoperative week as the graft’s viability is maintained by a diffusion process called plasmatic inhibition.15,33 A First-Line Option For Soft Tissue Wound Coverage? Once one has ensured proper preparation of the host and recipient wound sites, skin grafting represents a simple, cost-efficient technique that is powerful in providing rapid and stable soft tissue wound coverage. One recent study involved plastic surgeons as part of the multidisciplinary team for treating patients with diabetic foot wounds. In the study of 38 patients with diabetic foot wounds that required soft tissue coverage, more than 50 percent of the patients underwent skin grafting as the primary procedure for wound coverage.51 This data rightly positions skin grafting techniques as a first-line soft tissue wound coverage option in treating diabetic foot and ankle wounds when flap coverage is either unnecessary or inappropriate, and the use of topical wound care agents and living skin equivalents is considered too expensive and would prolong full wound coverage. Final Notes Soft tissue coverage of diabetic foot and ankle wounds is an evolving process that involves an elaborate series of potential conservative and surgical techniques. Unfortunately, few existing studies critically analyze long-term, follow-up reulceration rates when it comes to soft tissue coverage techniques of the plantar aspect of the foot.1,52-55 Most propose that no one form of soft tissue coverage is entirely satisfactory, and that patient education and proper shoe gear modifications are more important than the type of soft tissue wound coverage utilized.1,52-55 Gidumal, et. al., believed that the soft tissue coverage choices one utilizes should be governed by the surgeon’s discretion and donor site considerations alone.54 Levin and Serafin believe the choice of soft tissue wound coverage depends on the needs of the patient, the location of the lesion on the foot and the need for eliminating contour defects.2 Regardless of the technique one employs, it is essential to ensure that the host is medically prepared in order to maximize wound healing. The use of skin grafts and various flaps involving the foot and lower leg as donor sites represent advanced concepts based on sound, time-honored principles. When one ensures proper patient selection and technique, these procedures represent a simple, reproducible, minimally invasive and cost-effective means for surgical management of diabetic foot and ankle wounds in patients with well controlled medical comorbidities.56-58 Dr. Zgonis is an Assistant Professor within the Department of Orthopaedics/Podiatry Division at the University of Texas Health Science Center in San Antonio. He is also the Director of Fellowship Training Programs at the aforementioned institution. Dr. Zgonis is a Fellow of the American College of Foot and Ankle Surgeons, and is a Diplomate of the American Board of Podiatric Surgery. He can be reached via e-mail at: email@example.com Dr. Roukis is a Fellow of the American College of Foot and Ankle Surgeons, and is a Diplomate of the American Board of Podiatric Surgery. Dr. Cromack is an Assistant Professor within the Department of Orthopaedics/Hand and Plastic Surgery Division at the University of Texas Health Science Center in San Antonio. He is a Diplomate of the American Board of Plastic Surgery. For related articles, see “A Guide To Closure Techniques For Open Wounds” in the July 2003 issue of Podiatry Today or “Conquering Plastic Surgery Complications In Wound Care” in the July 2005 issue. Also visit the archives at www.podiatrytoday.com.
References 1. Sommerlad BC, McGrouther DA. Resurfacing the sole: long-term follow-up and comparison of techniques. Br J Plast Surg. 1978; 31: 107. 2. Levin LS, Serafin D. Plantar skin coverage. Prob Plast Reconstr Surg 1991; 1:156-184. 3. Attinger C. Soft-tissue coverage for lower-extremity trauma. Orthop Clin N Am 1995; 26:295-334. 4. Armstrong DG, Wunderlich RP, Lavery LA. Reaching closure with skin stretching: applications in the diabetic foot. Clin Podiatr Med Surg 1998; 15:109-116. 5. Cohen BK, Zabel DD, Newton ED, Catanzariti AR. Soft-tissue reconstruction for recalcitrant diabetic foot wounds. J Foot Ankle Surg 1999; 38:388-393. 6. Roukis TS. The Doppler probe for planning septofasciocutaneous advancement flaps on the plantar aspect of the foot: anatomical study and clinical applications. J Foot Ankle Surg 2000; 39:270-290. 7. Levin LS. The reconstructive ladder: an ortho-plastic approach. Orthop Clin N Amer 1993; 24:393-409. 8. Gottlieb LJ, Krieger LM. From the reconstructive ladder to the reconstructive elevator. Plast Reconstr Surg 1994; 93:1503-1504. 9. Bennett N, Choudhary S. Why climb a ladder when you can take the elevator? Plast Reconstr Surg 2000; 105:2266-2267. 10. Pearl RM, Johnson D. The vascular supply to the skin: an anatomical and physiological reappraisal-Part I. Ann Plast Surg 1983; 11:99-105. 11. Frykberg RG. Diabetic foot disorders: a clinical practice guideline. J Foot Ankle Surg 2000; 39:S1-60. 12. Brem H, Sheehan P, Boulton AJ. Protocol for treatment of diabetic foot ulcers. Am J Surg 2004; 187:S1-10. 13. Zgonis T, Jolly GP, Buren BJ, Blume P. Diabetic foot infections and antibiotic therapy. Clin Podiatr Med Surg 2003; 20:655-69. 14. Zgonis T, Jolly GP. The management of diabetic foot infections. OrthoKinetic Rev 2004; 4:22-6. 15. Jolly GP, Zgonis T, Blume P. Soft tissue reconstruction of the diabetic foot. Clin Podiatr Med Surg 2003; 20:757-781. 16. Levin LS. Personality of soft-tissue injury. Tech Orthop 1995; 10:65-72. 17. Roukis TS. Radical solutions: bold débridement techniques can work for both chronic and acute wounds. OrthoKinetic Rev 2004; 4:20-23. 18. Mustoe T. Understanding chronic wounds: a unifying hypothesis on their pathogenesis and implications for therapy. Am J Surg 2004; 187: S65-70. 19. Levin LS. Débridement. Tech Orthop 1995; 10:104-108. 20. Attinger CE, Bulan E. Blume PA. Surgical débridement: the key to successful wound healing and reconstruction. Clin Podiatr Med Surg 2000; 17:599-630. 21. Attinger CE, Bulan EJ. Débridement: the key initial first step in wound healing. Foot Ankle Clin 2001; 6:627-660. 22. Saap LJ, Falanga V. Débridement performance index and its correlation with complete closure of diabetic foot ulcers. Wound Repair Regen 2002; 10: 354-359. 23. Armstrong DG, Lavery LA, Vazquez JR, Nixon BP, Boulton AJ. How and why to surgically débride neuropathic diabetic foot wounds. J Amer Podiatr Med Assoc 2002; 92: 402-404. 24. Bahrs C, Schnabel M, Frank T, Zapf C, Mutters R, von Garrel T. Lavage of contaminated surfaces: an in vitro evaluation of the effectiveness of different systems. J Surg Res 2003; 112: 26-30. 25. Wheeler CB, Rodeheaver GT, Thacker JG, Edgerton MT, Edilich RF. Side-effects of high pressure irrigation. Surg Gynecol Obstet 1976; 143:775-778. 26. Sobel JW, Goldberg VM. Pulsatile irrigation in orthopaedics. Orthop 1985; 8:1019-1022. 27. Tobias AM, Chang B. Pulsed irrigation of extremity wounds: a simple technique for splashback reduction. Ann Plast Surg 2002; 48:443-444. 28. Ratner D. Skin grafting: from here to there. Dermatol Clin 1998; 16:75-90. 29. Ablove R, Howell RM. The physiology and technique of skin grafting. Hand Clin 1997; 13:163-173. 30. Wheeland RG. The technique and current status of pinch grafting. J Dermatol Surg Oncol 1987; 13:873-880. 31. Ahnlide I, Bjellerup M. Efficacy of pinch grafting in leg ulcers of different etiologies. Acta Dermatol Venereol 1997; 77:144-145. 32. Attinger C. Use of skin grafting in the foot. J Amer Podiatr Med Assoc 1995; 85: 49-56. 33. Donato MC, Novicki DC, Blume PA. Skin grafting: historic and practical approaches. Clin Podiatr Med Surg 2000; 17:561-598. 34. Converse JM, Smahel J, Ballantyne DL, Harper AD. Inosculation of vessels of skin graft and host bed: a fortuitous encounter. Br J Plast Surg 1975; 28:274-282. 35. Saponara GC, Warren AM. Pinch grafts: applications in podiatric wound closure. J Foot Surg 1988; 27: 111-115. 36. Simman R. Medial plantar arch pinch grafts are an effective technique to resurface palmer and plantar wounds. Ann Plast Surg 2004; 53:256-260. 37. Roukis TS. Use of the medial arch as a donor site for split-thickness skin grafts. J Foot Ankle Surg 2003; 42:312-314. 38. Mendicino RW, Statler TK, Catanzariti AR. Popliteal sciatic nerve blocks after foot and ankle surgery: an adjunct to postoperative analgesia. J Foot Ankle Surg 2002; 41:338-341. 39. Puttirutvong P. Meshed skin graft versus split-thickness graft in diabetic ulcer coverage. J Med Assoc Thai 2004; 87:66-72. 40. Perry VP. A review of skin preservation. Cryobiology 1960; 3:109-130. 41. Converse JM, Uhlschmid GK, Ballantyne DL. Plasmatic circulation in skin grafts. Plast Reconstr Surg 1969; 43:495-499. 42. Clemmesen T, Ronhovde DA. Restoration of the blood supply to human skin autografts. Scand J Plast Reconstr Surg 1960; 2:44-46. 43. Smahel J. The healing of skin grafts. Clin Plast Surg 1977; 4:409-424. 44. Schneider AM, Morykwas MJ, Argenta LC. A new and reliable method of securing skin grafts to the difficult recipient bed. Plast Reconstr Surg 1998; 102:1195-1198. 45. Chouhary S, Lam DGK. Simple tie-over: the herniotomy approach. Plast Reconstr Surg 1999; 104:1573-1574. 46. Fullerton JK, Smith CE, Milner SM. The “stegosaurus” dressing: a simple and effective method of securing skin grafts in the burn patient. Ann Plast Surg 2000; 45:462-464. 47. Eroglu L, Akba? H, Güneren E, Demir A, Uysal A. Securing skin grafts using a surgical glove. Plast Reconstr Surg 2001; 108:1459-1460. 48. Kaplan HY. A quick stapler tie-over fixation for skin grafts. Ann Plast Surg 1999; 22:173-174. 49. Stone P, Prigozen J, Hofeldt M, Hass S, DeLuca J, Flaherty S. Bolster versus negative pressure wound therapy for securing split-thickness skin grafts in trauma patients. Wounds 2004; 16:219-223. 50. Moisidis E, Heath T, Boorer C, Ho K, Deva AK. A prospective, blinded, randomized, controlled clinical trial of topical negative pressure use in skin grafting. Plast Reconstr Surg 2004; 14:917-922. 51. Baumeister S, Dragu A, Jester A, Germann G, Menke H. The role of plastic and reconstructive surgery within an interdisciplinary treatment concept for diabetic foot ulcers of the foot. Deutsch Med Wochenscr 2004; 129:676-680. 52. Nahai F. Discussion: free miscrovascular muscle flaps with skin graft reconstruction of extensive defects of the foot: a clinical and gait analysis study. Plast Reconstr Surg 1985; 75:640. 53. Noever G, Bruser P, Kohler L. Reconstruction of heel and sole defects by free flaps. Plast Reconstr Surg 1986; 78:345-352. 54. Gidumal R, Carl A, Evanski P, Shaw W, Waugh TR. Functional evaluation of nonsensate free flaps to the sole of the foot. Foot Ankle 1986; 7:118-123. 55. Nohira K, Shintomi Y, Sugihara T, Ohura T. Replacing losses in kind: improved sensation following heel reconstruction using free instep flap. J Reconstr Microsurg 1989; 5:1-6. 56. Zgonis T, Roukis TS. A systematic approach to diabetic foot infections. Adv Ther 2005; 22:244-262. 57. Roukis TS, Zgonis T. Skin grafting techniques for soft-tissue coverage of diabetic foot and ankle wounds. J Wound Care 2005; 14:173-176. 58. Roukis TS, Zgonis T. Modifications of the great toe fibular flap for diabetic forefoot and toe reconstruction. Ostomy Wound Manage 2005; 51:30-34.