INTRODUCTION TO SPLIT-THICKNESS SKIN GRAFTS

In the realm of orthopaedic trauma and reconstructive surgery, the management of extensive soft tissue defects remains a formidable challenge. When primary closure is impossible or contraindicated due to excessive tension, split-thickness skin grafts (STSGs) serve as a foundational technique for achieving durable, functional wound coverage. Unlike full-thickness skin grafts (FTSGs), which include the entire epidermis and dermis, an STSG consists of the complete epidermis and a variable portion of the underlying dermis.

The inclusion of only a partial thickness of the dermis allows the donor site to re-epithelialize spontaneously from retained epidermal appendages (hair follicles, sebaceous glands, and sweat glands). STSGs are highly versatile, requiring less robust vascularity at the recipient bed compared to FTSGs or local flaps, making them the workhorse for covering large defects, fasciotomy wounds, and granulating beds following severe trauma or tumor resection.

Clinical Pearl: The survival of an STSG is inversely proportional to its thickness, whereas the durability and cosmetic outcome of the graft are directly proportional to its thickness. Thinner grafts "take" more readily but are prone to secondary contracture; thicker grafts resist contracture but demand a highly vascularized recipient bed.

PHYSIOLOGY AND BIOMECHANICS OF GRAFT SURVIVAL

Understanding the physiological phases of graft "take" is paramount for the orthopaedic surgeon, as deviations in surgical technique or postoperative immobilization directly disrupt these mechanisms. Graft survival occurs in three distinct, overlapping phases:

1. Plasmatic Imbibition (0 to 48 hours): Immediately upon placement, the graft is ischemic. It survives by passively absorbing a plasma-like transudate from the recipient bed via capillary action. The graft swells and may appear pale or edematous.
2. Inosculation (48 to 72 hours): A critical vascular network begins to form. The severed capillary ends of the graft align and anastomose with the capillary buds proliferating from the recipient bed.
3. Angiogenesis and Neovascularization (72 hours onward): True blood flow is established as new vessels grow directly into the graft dermis. The graft transitions from a pale appearance to a healthy pink.

Surgical Warning: Any accumulation of fluid (hematoma or seroma) or application of shearing forces during the first 72 hours will physically separate the graft from the recipient bed, preventing inosculation and leading to catastrophic graft necrosis.

PREOPERATIVE PLANNING AND DONOR SITE SELECTION

The selection of an appropriate donor site requires careful consideration of the required graft size, the patient's age, skin quality, and aesthetic concerns.

Standard Donor Sites

The anterior and lateral aspects of the thigh are the most universally utilized donor sites for large STSGs. They offer a broad, flat surface that is easily accessible and hidden by standard clothing. The medial aspect of the arm, just inferior to the axilla, is another excellent option for medium-sized grafts, providing relatively hairless skin.

Specialized Donor Sites

Frequently, only a small or "postage stamp" graft is required.
* Forearm: While convenient as it can often be accessed within the same operative field as a hand or wrist injury, harvesting from the forearm is generally undesirable due to the highly visible, cosmetically displeasing scar it leaves.
* Hypothenar Eminence: The hypothenar area of the palm is an exceptional donor site for obtaining satisfactory STSGs specifically for skin loss on the fingertips. The glabrous nature of this skin provides an excellent functional and aesthetic match for volar digit reconstruction.
* Submammary Fold: In some older women, skin is readily available inferior to a pendulous breast. This site can yield a substantial graft without leaving a readily visible scar.
* Lower Abdomen and Buttock: In elderly individuals and young children, the skin is inherently thinner and more fragile. If a graft thicker than 0.010 inch is required in these populations, the lower abdominal wall or buttock skin is preferred to prevent delayed donor site healing or full-thickness donor site necrosis.

Graft Thickness Parameters

Split-thickness skin grafts vary significantly in thickness based on patient demographics and clinical requirements:
* Infants and Toddlers: Typically harvested at 0.008 inch.
* Adults: Standard harvesting thickness ranges from 0.012 to 0.015 inch.
* Elderly: Require conservative thickness settings (often 0.010 inch or less) unless utilizing the abdomen or buttock, due to age-related dermal atrophy.

SURGICAL TECHNIQUE: HARVESTING THE STSG

Equipment Preparation

Two types of mechanical dermatomes are in widespread use for harvesting split-thickness grafts: powered (electrical or pneumatic) dermatomes (e.g., Zimmer, Padgett) and manual dermatomes (e.g., Watson, Humby). Powered dermatomes are preferred in modern orthopaedic practice due to their precision, consistency, and ease of use.

Prior to harvesting, the surgeon must meticulously assemble the dermatome, ensuring the blade is seated correctly and the width plate (typically 1 to 4 inches) matches the defect size. The thickness dial must be calibrated and double-checked by the surgeon.

Step-by-Step Harvesting Procedure

1. Positioning and Preparation: The donor site is shaved, prepped, and draped. The limb must be positioned to provide a firm, unyielding surface.
2. Lubrication: Sterile mineral oil or normal saline is applied generously to both the donor skin and the undersurface of the dermatome to minimize friction and prevent the device from stuttering, which causes irregular graft thickness.
3. Traction and Counter-Traction: An assistant uses a sterile tongue depressor or a specialized traction plate to pull the skin taut just ahead of the dermatome. The surgeon applies counter-traction proximally. A flat, tense surface is absolute paramount.
4. The Glide: The dermatome is activated before contacting the skin. It is applied to the skin at a 45-degree angle until the blade engages, then leveled to a 15- to 20-degree angle. The surgeon advances the dermatome with steady, firm, downward and forward pressure.
5. Completion: Once the desired length is achieved, the dermatome is angled upward to cleanly sever the distal edge of the graft.

Pitfall: Pushing the dermatome too forcefully or failing to maintain adequate skin tension will result in "chatter" marks, creating a corrugated graft with alternating areas of full-thickness harvesting and skipped areas.

Graft Meshing

Once harvested, the graft is often passed through a mechanical skin mesher (commonly at a 1:1.5 or 1:3 ratio). Meshing serves two critical functions:
1. It allows the graft to expand, covering a surface area larger than the donor site.
2. It creates fenestrations that permit the egress of blood and serum, drastically reducing the risk of subgraft hematoma or seroma formation.
Note: Grafts applied to the face, neck, or palmar surfaces of the hands are typically left unmeshed (sheet grafts) to optimize cosmetic and functional outcomes.

DERMAL REGENERATION TEMPLATES (INTEGRA)

A fundamental rule of skin grafting is that an STSG will not survive on "bare" structures lacking a capillary bed. Grafts cannot be placed directly over bare bone (without periosteum), bare tendon (without paratenon), or bare articular cartilage. Historically, these defects mandated complex local or free tissue transfer (flaps).

Today, dermal regeneration templates, such as Integra (Integra LifeSciences Corp., Plainsboro, NJ), offer a powerful alternative.

Composition and Mechanism

Integra is a bilayer synthetic skin substitute.
* The Dermal Layer: Composed of a porous matrix of cross-linked bovine type I collagen and shark chondroitin-6-sulfate (glycosaminoglycan). This matrix acts as a scaffold for the patient's own fibroblasts and endothelial cells to infiltrate and generate a neodermis.
* The Epidermal Layer: A temporary silicone sheet that acts as a mechanical barrier to prevent moisture loss and bacterial invasion while the neodermis forms.

Clinical Application in Orthopaedics

Weigert et al. reported the highly successful use of Integra for the management of 15 severe traumatic hand wounds complicated by bone, joint, or tendon exposure. In their series, split-thickness grafting was performed at an average of 26 days after the initial injury and Integra application. In 13 of the 15 hands, durable, functional, and aesthetic coverage was obtained.

Advantages of Dermal Templates:
* Potentially eliminates the need for morbid local rotational or free-flap coverage.
* Ease of use and immediate availability in large quantities and various sizes.
* Provides a thicker, more pliable, and less contracted wound bed compared to STSG alone.

Disadvantages and Limitations:
* High material cost.
* Requires a two-stage surgical procedure (Stage 1: Template application; Stage 2: Silicone removal and STSG application 3-4 weeks later).
* A distinct learning curve for optimal use.
* Higher risk of seroma or hematoma formation beneath the silicone layer, which can lead to template loss.

RECIPIENT SITE PREPARATION AND GRAFT APPLICATION

The success of an STSG is entirely dependent on the quality of the recipient bed. The wound must be meticulously debrided of all necrotic tissue, foreign bodies, and bacterial biofilm. Hemostasis must be absolute; pinpoint bleeding is acceptable, but active oozing will inevitably lift the graft.

The graft is transferred to the recipient bed and oriented with the dermal (matte, lighter) side down. It is secured using skin staples, fine non-absorbable sutures (e.g., 4-0 or 5-0 nylon), or fibrin tissue sealant. The graft must be applied under slight tension to restore normal resting skin tension, which optimizes inosculation.

Bolster Dressings and Negative Pressure Wound Therapy (NPWT)

To prevent shearing forces and eliminate dead space, a tie-over bolster dressing is traditionally employed. Non-adherent gauze (e.g., Xeroform) is placed over the graft, followed by fluffed cotton or a sponge, which is then tied down using the peripheral sutures left long during graft fixation.

Increasingly, Negative Pressure Wound Therapy (NPWT or wound VAC) is utilized as the ultimate bolster. Applied at -75 to -125 mmHg continuous pressure, NPWT splints the graft perfectly against the undulating contours of the recipient bed, actively evacuates transudate and blood, and virtually eliminates shearing forces.

MANAGEMENT OF THE DONOR AREA

The donor site is essentially a clean, partial-thickness wound. Its management is often more painful for the patient than the recipient site and requires meticulous care to prevent conversion to a full-thickness wound. Several acceptable methods are utilized:

The Open/Drying Technique

In this traditional method, the donor area is dressed with a single layer of finely woven nylon or silk gauze (e.g., Owen's silk) or a bismuth tribromophenate mesh.
* Mechanism: Blood and serum coagulate within the interstices of the gauze, forming a hard, protective eschar. As the wound re-epithelializes beneath the eschar over 10 to 14 days, the gauze spontaneously detaches.
* Warning: If secondary dressings placed over this layer prevent drying, the donor area tends to become macerated. Maceration invites secondary bacterial infection, which can cause necrosis of the remaining dermal appendages, converting the wound to a full-thickness defect that may itself require skin grafting later. Otherwise, the part is left uncovered, and rapid drying of the area is encouraged. Bed sheets should be kept strictly off the donor site using a rigid bed cradle support.

The Closed/Moist Environment Technique

Modern wound healing principles favor a moist environment to accelerate re-epithelialization and reduce pain. In this technique, a synthetic semi-permeable adhesive film (e.g., Tegaderm, Opsite) or a hydrocolloid dressing is placed directly over the donor site.
* Mechanism: Serum and blood accumulate beneath the film daily for the first 1 to 2 days. If the fluid accumulation threatens to break the seal, the fluid can be aspirated with a fine needle, or the film is carefully changed.
* Progression: After 7 to 10 days, the film can be removed, and the area is left open, usually demonstrating highly satisfactory, rapid healing with significantly less patient discomfort compared to the drying technique.

POSTOPERATIVE PROTOCOL AND REHABILITATION

Postoperative care is dictated by the location of the graft.
1. Immobilization: Joints adjacent to the grafted area must be strictly immobilized using splints or external fixators for a minimum of 5 to 7 days to prevent shear.
2. Elevation: The grafted extremity must be continuously elevated to minimize venous congestion and edema, which can compromise plasmatic imbibition.
3. First Dressing Change: If NPWT is used, it is typically removed on postoperative day 4 or 5. Traditional bolsters are removed around day 5. The graft is inspected for "take" (adherence and pink color). Hematomas or seromas, if small, can be carefully evacuated by rolling a sterile cotton swab toward a meshed fenestration or by making a small nick in the graft.
4. Rehabilitation: Once graft take is secure (typically day 10-14), gentle active range of motion is initiated. The newly grafted skin lacks sebaceous glands and will be exceedingly dry; patients must be instructed to apply non-perfumed emollients (e.g., cocoa butter, mineral oil) multiple times daily. Compression garments are often prescribed for 6 to 12 months to prevent hypertrophic scarring and manage edema.

CONCLUSION

Split-thickness skin grafting remains an indispensable skill in the orthopaedic surgeon's armamentarium. Mastery of this technique requires not only precise surgical execution during harvesting and application but also a profound understanding of wound bed physiology, the strategic use of dermal regeneration templates for complex defects, and rigorous postoperative management of both the donor and recipient sites. Through meticulous adherence to these evidence-based principles, surgeons can achieve reliable, functional, and durable soft tissue reconstruction in even the most challenging clinical scenarios.

📚 Medical References

• split-thickness skin grafts in burns of the hand, J Burn Care Rehabil 22:390, 2001.
• Marble K, Fudem G: First web space release with the dorsal hand rotation fl ap: closing the donor site, Ann Plast Surg 35:83, 1995.
• May JW Jr, Barlett SP: Staged groin fl ap in reconstruction of the pediatric hand, J Hand Surg 6A:163, 1981.
• McCabe SJ, Breidenbach WC: The role of emergency free fl aps for hand trauma, Hand Clin 15:275, 1999.
• McGregor IA: Flap reconstruction in hand surgery: the evolution of presently used methods, J Hand Surg 4A:1, 1979.
• [McGregor IA: Fundamental techniques of plastic surgery, New York, 1980, Churchill Livingstone.

McGregor IA: Axial pattern fl aps. In Tubiana R, ed: The hand, vol 2, Philadelphia, 1985, Saunders. Medalie DA: Perforator-based forearm and hand adipofascial fl aps for the coverage of diffi cult dorsal hand wounds, Ann Plast Surg 50:103, 2003.](https://pubmed.ncbi.nlm.nih.gov/?term=McGregor%20IA%3A%20Fundamental%20techniques%20of%20plastic%20surgery%2C%20New%20York%2C%201980%2C%20Churchill%20Livingstone.%0A%0AMcGregor%20IA%3A%20Axial%20pattern%20%EF%AC%82%20aps.%20In%20Tubiana%20R%2C%20ed%3A%20The%20hand%2C%20vol%202%2C%20Philadelphia%2C%201985%2C%20Saunders.%20Medalie%20DA%3A%20Perforator-based%20forearm%20and%20hand%20adipofascial%20%EF%AC%82%20aps%20for%20the%20coverage%20of%20dif%EF%AC%81%20cult%20dorsal%20hand%20wounds%2C%20Ann%20Plast%20Surg%2050%3A103%2C%202003.)
- Moran SL, Berger RA: Biomechanics and hand trauma: what you need, Hand Clin 19:17, 2003.
- Morrison CM, Thompson NW, Herbert KJ, et al: Missed injuries in the acutely traumatized hand, Ulster Med J 72:22, 2003.
- Muirragui AG, Santamaria G: Composite osteoarthrotenocutaneous free fl ap from the foot for reconstruction of an unusual hand wound, Plast Reconstr Surg 100:986, 1997.
- Neumeister MW, Brown RE: Mutilating hand injuries: principles and management, Hand Clin 19:1, 2003.
- Olding M: Reversed forearm fl ap based on an “exteriorized” pedicle, J Hand Surg 16A:157, 1991.
- Pagliei A, Rocchi L, Tulli A: The dorsal fl ap of the fi rst web, J Hand Surg 28B:121, 2003.
- Paneva-Holevich E, Holevich Y: Further experience with the bipedicled neurovascular island fl ap in thumb reconstruction, J Hand Surg 16A:594, 1991.
- Park JJ, Kim JS, Chung JI: Posterior interosseous free fl ap: various types, Plast Reconstr Surg 100:1186, 1997.
- Pelissier P, Genin-Etcheberry T, Casoli V, et al: Limits and indications of the dorsal transposition fl ap: critical evaluation of 15 cases, J Hand Surg 26A:277, 2001.
- Pelzer M, Sauerbier M, Germann G, et al: Free “kite” fl ap: a new fl ap for reconstruction of small hand defects, J Reconstr Microsurg 20:367, 2004.
- Penteado CV, Masquelet AC, Chevrel JP: The anatomic basis of the fascio-cutaneous fl ap of the posterior interosseous artery, Surg Radiol Anat 8:209, 1986.
- Quinn J, Cummings S, Callaham M, et al: Suturing versus conservative management of lacerations of the hand: randomised controlled trial, BMJ 325:299, 2002.
- Rank BK, Wakefi eld AR: Surgery of repair as applied to hand injuries, Baltimore, 1960, Williams & Wilkins. Raskin KB: Acute vascular injuries of the upper extremity, Hand Clin 9:115, 1993.
- Rose EH, Buncke HJ: Free transfer of a large sensory fl ap from the fi rst web space and dorsum of the foot including the second toe for reconstruction of a mutilated hand, J Hand Surg 6A:196, 1981.
- Rui Y, Shou K, Zhang Q, et al: Combined free-tissue transfer for primary reconstruction of radial part of the hand, Microsurgery 24:59, 2004.
- Russell RC, Bueno RA Jr, Wu TY: Secondary procedures following mutilating hand injuries, Hand Clin 19:149, 2003.
- Sanders JO, Weiland AJ, Moore JR: Leiomyosarcoma of the forearm: treatment with wide local excision and a lateral arm fl ap, J Hand Surg 11A:906, 1986.
- Scheker LR: Salvage of a mutilated hand. In Cohen M, ed: Mastery of plastic and reconstructive surgery, Boston, 1994, Little, Brown. Scheker LR, Kleinert HE, Hanel DP: Lateral arm composite tissue transfer to ipsilateral hand defects, J Hand Surg 12A:665, 1987.
- Shaw DT, Payne RL: One-staged tubed abdominal fl aps: single, pedicle tubes, Surg Gynecol Obstet 83:205, 1946.
- Sherif MM: First dorsal metacarpal artery fl ap in hand reconstruction: I. Anatomic study, J Hand Surg 19A:26, 1994.
- Sherif MM: First dorsal metacarpal fl ap in hand reconstruction: II. Clinical application, J Hand Surg 19A:32, 1994.
- Smith PJ, Ross DA: Tubed radial fascial fl ap and reconstruction of the fl exor apparatus in the forearm, J Hand Surg 18A:959, 1993.
- Song R, Gao Y, Song Y, et al: The forearm fl ap, Clin Plast Surg 9:21, 1982.
- Song R, Song Y, Yu Y, et al: The upper arm free fl ap, Clin Plast Surg 9:27, 1982.
- Sorock GS, Lombardi DA, Hauser RB, et al: Acute traumatic occupational hand injuries: type, location, and severity, J Occup Environ Med 44:345, 2002.
- Sorock GS, Lombardi DA, Hauser RB, et al: A case-crossover study of transient risk factors for occupational acute hand injury, Occup Environ Med 61:305, 2004.
- Stricker SJ, Burkhalter WE, Ouellette AE: Single-vessel forearm arterial repairs: patency rates using nuclear angiography, Orthopedics 12:963, 1989.
- Suominen S, Asko-Seljavaara S: Thermography of hands after a radial forearm fl ap has been raised, Scand J Plast Reconstr Surg Hand Surg 30:307, 1996.
- Tezcan M, Ozcan M, Kahveci R, et al: A new fl ap from the dorsum of the fi rst intermetacarpal area: the fi rst dorsal intermetacarpal fl ap, Plast Reconstr Surg 100:914, 1997.
- Tomaino MM: Treatment of composite tissue loss following hand and forearm trauma, Hand Clin 15:319, 1999.
- Tubiana R: Skin fl aps. In Tubiana R, ed: The hand, vol 2, Philadelphia, 1985, Saunders. Tubiana R: Skin fl aps. In Tubiana R, ed: The hand, vol 3, Philadelphia, 1988, Saunders. Via RM: Suturing unnecessary for hand lacerations under 2 cm, J Fam Pract 52:23, 2003.
- Weinzweig N, Chen L, Chen ZW: The distally based radial forearm fasciosubcutaneous fl ap with preservation of the radial artery: an anatomic and clinical approach, Plast Reconstr Surg 94:675, 1994.
- Wilgis EF: Vascular injuries and diseases of the upper limb, Boston, 1983, Little, Brown. Xarchas KC, Chatzipapas C, Koukou O, et al: Upper limb fl aps for hand reconstruction, Acta Orthop Belg 70:98, 2004.
- Yang D, Morris SF: Vascular basis of dorsal digital and metacarpal skin fl aps, J Hand Surg 26A:142, 2001.
- Yang G, Chen B, Gao Y, et al: Forearm skin fl ap transposition, Natl Med J China 61:139, 1981.
- Yoshimura M, Shimada T, Imura S, et al: The venous skin graft method for repairing skin defects of the fi ngers, Plast Reconstr Surg 80:243, 1987.
- Zancolli EA, Angrigiani C: Posterior interosseous island forearm fl ap, J Hand Surg 13B:130, 1988.