Exploring The Potential Of Acellular Dermis Grafts For Wound Healing And Soft Tissue Repair

Author(s): 
J. Palmer Branch, DPM, FACFAS

Offering insights from the literature, practical pearls and coding tips, this author discusses the use of acellular dermis grafts for foot and ankle applications including wound healing, tendon and ligament repair and soft tissue supplementation.

Allogenic dermis grafts have been used for many years, traditionally as temporary wound cover in burn and other large wounds. Newer acellular versions, processed to remove the cellular components, are gaining in popularity and usefulness in numerous clinical applications. More recent clinical uses involve use of the graft as a scaffold allowing for new tissue ingrowth, adding structural support to soft tissues, or to act as a filler or spacer. Foot and ankle applications include wound healing (diabetic ulcers and others), tendon and ligament repair, soft tissue supplementation, and joint resurfacing.

   Classically, skin grafts are obtained from the patient (autograft) as full or partial-thickness skin grafts. Donor site morbidity limitations and durability concerns of the healed skin, especially for thin split-thickness skin grafts, have previously restricted use.

   Fresh frozen donor dermis grafts (allograft) originally applied to severe burn wounds were used as temporary covers only due to issues of antigenicity and subsequent graft rejection.

   Acellular dermis grafts (a.k.a. acellular dermal matrix grafts) are derived from cadaveric (donor) skin. Much like the fresh frozen donor grafts, their original purpose was to serve as a cover for exposed periosteum in severe burn wounds.1 Acellular dermis grafts, however, are processed to remove living cells to greatly reduce the risk of rejection. These grafts have inherent favorable attributes which optimize their usefulness in different clinical scenarios.

   The structure of the graft facilitates ingrowth of new tissue allowing the graft to serve as a scaffold. These acellular dermis grafts have a reticular side (derived from deeper dermal layers) which facilitates revascularization and new tissue ingrowth. The preservation of vascular channels present in the deeper dermal tissues particularly aid rapid revascularization. This is regardless of the recipient tissue type.

   Some of the more commonly encountered brands of acellular dermis grafts include: GraftJacket (meshed) (KCI), Alloderm (LifeCell), GraftJacket (non-meshed) (Wright Medical Technology), hMatrix (Bacterin Biologics), DermaSpan (Biomet) and TheraSkin (Synthes).2-5

   A wide variety of other graft materials have been in use for wound healing and soft tissue repair. Xenografts include OrthAdapt (Synovis Life Technologies), CuffPatch (Biomet) and Restore (DePuy).6 Synthetic grafts include Integra (Integra Life Sciences) and Marlex (Bard). Skin substitutes include Dermagraft (Shire Regenerative Medicine) and Apligraf (Organogenesis).6-8

   Xenografts have applications similar to acellular dermis grafts. They have the ability to act as scaffolds and have significant tensile strength.8,9 Since these grafts are of animal origin, significant rejection risk exists.9,10

   Other grafts may not act as a scaffold but serve other purposes. Grafts such as Integra provide temporary wound cover, allowing undisturbed healing below the graft. Skin substitutes such as Dermagraft and Apligraf facilitate healing via release and/or promotion of the release of growth factors to stimulate wound healing.7

   An ideal graft should not be reactive to the recipient tissue and facilitate ingrowth of new tissue (i.e. serve as a scaffold). Basically, the theory is that acellular dermis grafts can be transformed into tissue similar to the recipient tissue in which it is placed. Such tissue may be skin, tendon, ligament or, theoretically, cartilage.3,7,11

What You Should Know About The Processing Of Acellular Dermis Grafts

The grafts undergo various chemical processes and freeze drying to remove the cellular components to minimize the risk of graft rejection. Every manufacturer has subtle differences in graft processing. Processing variations slightly alter graft handling and behavior clinically, leading to surgeon or facility graft preferences. Some grafts require refrigeration while others allow room temperature storage. The varying evidence of success in clinical studies may also affect surgeon preferences. Prior to application in the operating room, the grafts are typically thawed (a.k.a. reconstitute) in normal saline.

A Guide To Surgical Applications

Acellular dermis grafts come in many sizes and thicknesses. Generally, thinner grafts are for wounds or small tendon repair, and incorporate more rapidly. The thicker grafts have more tensile strength but incorporate more slowly.

   Surgical applications are not limited to the foot and ankle. The applications include:
• wounds (surgical, diabetic foot, traumatic, venous stasis ulcers and others)7
• tendon repair (wrap or weave techniques)12
• joint resurfacing (first metatarsophalangeal joint, ankle joint)11
• oral surgery (gingival augmentation and cleft palate repair)
• ligament repair
• hernia repair
• soft tissue supplementation (plastic surgery and plantar soft tissue)
• burn wounds
• leg fascia repair
• rotator cuff repair9,13,14
• hernia repair
• breast reconstruction (post-mastectomy)

Assessing The Efficacy Of Dermis Grafts In Wound Healing

Historically, donor dermis grafts were used primarily on burn wounds. These grafts were traditionally removed once the wound healed sufficiently below the graft to be a good recipient bed for split-thickness skin graft application. In recent years, the acellular dermal matrix grafts are left in place to allow a scaffold effect for new tissue ingrowth. This ability is facilitated by the microscopic framework of the grafts that have retained structural components including vascular channels. This author likes to think of the acellular dermis grafts as a means to improve the quality of the wound bed to facilitate epithelialization.

   The grafts are often meshed prior to application for wounds to help prevent hematoma and seroma formation as well as to increase the wound surface area that the graft can cover. The graft is then applied with the reticular side against the wound. To help identify the reticular side, a drop of blood can be placed on the graft and observation for more rapid resorption on the reticular side.

   Use of negative pressure therapy (e.g. Vacuum Assisted Closure {VAC, KCI}) can enhance acellular dermis graft incorporation.15-17 The benefits of VAC Therapy include enhanced graft wound bed adherence, wound volume reduction, localized hyperemia, microstrain on wound cells (stimulates granulation), angiogenesis stimulation and wound exudate removal.

Flowable/Injectable Versions Of Acellular Dermis Grafts

Several manufacturers have injectable pulverized acellular dermis graft versions that are indicated for tunneling wounds. Such grafts can provide an effective collagen medium for ingrowth of granular tissue. Careful application techniques are necessary for prevention of graft egress from the wound.

   Tunneling wounds in the foot or ankle may indicate the presence of a deep chronic infection such as osteomyelitis. Communication of the wound with a joint or tendon sheath can allow for extensive drainage of synovial fluid, impairing the ability to heal even with grafting unless the deeper defect is closed. An appropriate workup including thorough clinical wound inspection, surgical exploration or radiographic imaging modalities is essential.

Pertinent Insights On Acellular Grafts For Soft Tissue Repair

An improved understanding of how these grafts enhance the healing process as well as seeing how these grafts have functioned in various clinical settings have helped allow the development of new graft applications. The inherent tensile strength of these grafts also allows successful use in the repair of tendons, ligaments and other structures where the graft helps augment the repair strength.5 7,12,13,18 The tensile strength of the graft varies according to graft thickness and size. For a standard thickness graft, Barber and colleagues have reported the tensile strength to be 182 N (range +/- 50N).18

   For tendon repair, most authors describe repair techniques in which the tendon ends are first reapproximated and sutured in a Bunnell or Krakow fashion. The acellular dermis graft is then wrapped around the repair site and sutured to enhance the tensile strength.18-20 (Picture 3) Barber and colleagues found that Achilles tendon wrap repair in cadaver models had a failure point of 455 N versus 217 N for standard suturing.18 This added strength allows for earlier active tendon mobilization, which improves the rehabilitation.18,21 Appropriate aggressive use of heavy gauge sutures with adequate purchase of tendon and graft is advisable.18-20

   In these standard cannoli-wrap techniques, the suture grasps the tendon. When a tensile force exerts itself along the tendon course, stress focuses on the tendon-suture interface as well as the suture-graft interface along the direction of the applied force. Thompson notes that the typical failure point is at the suture–tendon interface rather than the interface of the suture and the graft.22

   Recently, techniques have been described where one weaves strips of acellular dermis graft through the tendon repair site. Such techniques then use the graft strip instead of suture to purchase (i.e. grasp) the tendon. In the “strip and shoelace technique,” one first re-approximates and repairs the Achilles rupture in a Bunnell technique under physiologic tension. Then inlay a 1 to 1.5 cm strip of the acellular dermis graft within the tendon across the repair site parallel to the tendon course and suture it. Then cut the remainder of the graft in a zigzag fashion to create a very long 0.5 to 1 cm wide strip. (Picture 4) Cut one end of the graft into a very thin, tapered tip and pass it through the eye of a large Mayo needle. (Picture 5) Then weave the graft like a shoelace up and down the repair site. (Pictures 6,7) One can cut the corners on the graft to allow for easier passage of the graft through the tendon.12

   The long weaves of techniques such as the strip-and-shoelace technique redistribute the tension throughout the weave and help transform the tension force on the graft into a compression force on the tendon much like a braided rope. This not only reduces the tension on the graft strip but also cinches down the thickness of the repair site. This cinching reduces the inherent bulk of the repair site enhancing the ability to close the paratenon or tendon sheath with less tension. (Picture 7) In addition, by having the three separate parts of the repair (primary suturing, inlay strip graft, and woven graft in a shoelace pattern), there are two backup components should one fail.12

Using Acellular Dermis Grafts For Ankle Ligament Repair

Techniques to repair the lateral ankle ligaments using soft tissue grafts have also been described.6 A classic Brostrom primary repair technique is often used to repair the anterior talofibular and calcaneofibular ligaments in a “vest-over-pants” technique. A simple flat onlay of the acellular dermis graft can then be sutured over the repair to enhance the strength). I prefer a more anatomic lateral ankle ligament reconstruction involving an acellular dermis graft strip (e.g. DermaSpan™ in this case) passed through a drill hole in the fibula. A number of authors have described this technique using either a harvested peroneal tendon strip or other grafts (e.g. OrthoAdapt™).6

   Locate the anatomic courses of the anterior talofibular and calcaneofibular ligaments. Pass the graft through a drill hole in the fibula placed adjacent to the insertion points of the anterior talofibular and calcaneofibular ligaments to roughly interconnect the two points. Then place the graft over the ligaments and suture it. Soft tissue anchors may strengthen the attachments to bone. (Pictures 8-9).

Soft Tissue Supplementation Procedures

Rocchio describes a “parachute” technique where an acellular dermis graft is placed below the dermis via a small incision approach. This is typically done to augment atrophic subcutaneous tissue (e.g. fat pad) under a bony prominence to reduce pain or prevent recurrent ulceration. A small incision is made adjacent to the prominence. A thick acellular dermis graft is placed below the subcutaneous fat and pulled into place via sutures on the opposite of the margin from the incision. The incision is then closed burying the graft in between the patient’s skin and the bony prominence.23

Key Pointers On Joint Resurfacing And Using Grafts As Joint Spacers

Several authors have described techniques of using acellular dermis grafts in a joint resurfacing application.11 The degenerated articular cartilage is removed and the graft is then placed over the subchondral bone (typically left intact). The graft material acts as an anatomic spacer. Techniques and cases have focused on the first metatarsophalangeal joint with a series of patients showing good long-term success.11 This new area of application would seem to warrant more long-term studies to determine the durability and subsequent incorporation of the grafts, as well as ultimate success in achieving long-term pain relief.

Case Study: Abscess With Extensive Soft Tissue Defect

A 42-year-old female with new-onset diabetes presented with a large abscess encompassing almost the entire dorsal aspect of her left foot and a gangrenous fourth toe. After an appropriately aggressive incision and drainage including fourth toe amputation, administration of intravenous antibiotics and local wound care, the wound was adequately clean and viable. (Picture 10).

The size of the wound as well as the exposed tendon and bone put the wound at significant risk for infection or failure to heal if allowed to heal by secondary intention alone. I decided to apply an acellular dermis graft to facilitate healing.

   I debrided the wound and flushed it with a pulse lavage in the operating room. (Picture 11) I placed absorbable calcium sulfate beads with vancomycin. I meshed a 5 x 10 cm Bacterin hMatrix® acellular dermis graft and placed it on the wound. (Picture 12) A VAC® device facilitated healing. The wound was granulated well through the graft over time. (Pictures 13, 14) Sequential applications of Dermagraft then stimulated epithelialization. (Pictures 15-17)

How To Code For Acellular Dermis Graft Procedures

Surgical procedure codes frequently change and are expected to be overhauled if and when the final release and implementation of ICD-10 codes occurs.24,25 At the time of the submission of this article for publication in 2012, the following coding suggestions were felt to be most applicable by this author. Individual insurance payor guidelines may vary. Most procedures (except debridements) have a 90-day global period.

Supply code for acellular dermis graft – Q4107 per square cm

Wound prep of ulcer for graft application
(* specify by surface area/location)
15000 – 15004 (depending on payer guidelines)
Vs. Standard ulcer debridement codes – 11042-11044

Applying The Graft To Wounds

15271 Allograft temporary wound closure - legs; first 25 cm2 or less
15272 Allograft temporary wound closure - legs; each additional 100 cm2
15273 Allograft temporary wound closure - legs; first 100 cm2 or less
15274 Allograft temporary wound closure - legs each additional 100 cm2
15275 Allograft temporary wound closure - feet; first 25 cm2 or less
15276 Allograft temporary wound closure – feet; each additional 25 cm2
15277 Allograft temporary wound closure - feet; first 100 cm2 or less
15278 Allograft temporary wound closure - feet each additional 100 cm2

Negative Pressure Wound Therapy Monitoring (In General)

97605 - Less than 50 cm2
97606 - Greater than 50 cm2
*No global period – either code.
*Application of VAC generally not reimbursable.

Tendon Repair

Repair of extensor tendon
Foot – 28208
Ankle/leg - 27664

Repair of extensor tendon, secondary, with or without graft
Foot - 28210
Ankle/leg - 27665

Repair of Achilles tendon –primary –open or percutaneous – 27650
With graft – primary 27652

Repair, secondary, Achilles tendon with or without graft - 27654

Repair of flexor tendon (primary or secondary)
Foot - 28200
Ankle/leg - 27658

Repair of flexor tendon with free graft (includes obtaining graft)
Foot - 28202
Ankle/leg - 27665

   There has been some debate among various coding experts on whether the acellular dermis graft warrants the graft repair code. It is the opinion of this author that the application and suturing or weaving of an acellular dermis graft to strengthen the repair site does represent adequate work to warrant billing of this higher level code.

Ankle Ligament Repair

Primary Brostrom repair – single ligament – 27695
Both collateral ligaments – 27696
Secondary anatomic ligament reconstruction with graft- 27698

   It would be my opinion that the simple onlay graft of the dermis graft over a Brostrom-type repair would be billable as a primary repair. Procedures where the dermis graft is used in more substantial ligament reconstructive techniques would be more appropriately billed at the higher code level.

Joint Resurfacing

Arthroplasty of first metatarsophalangeal joint – 28292 (generally applicable for use of dermis graft resurfacing)

Arthroplasty of first metatarsophalangeal joint with metallic or silicone implant- 28293

Arthroplasty of lesser metatarsophalangeal joint – 28288
(same code for ostectomy, partial of each metatarsal head)

Arthroplasty of ankle – 27700

   Although there is a code for ankle arthroplasty with implant (27702), this generally refers to the metallic ankle implants. This is significantly different from the resurfacing procedure. Consideration could be given for use of the ankle arthroplasty code with a -22 modifier (“additional work”) or to use the unlisted procedure code (28899). Preauthorization from private insurance carriers may be necessary, depending on the payor.24,25

In Conclusion

Acellular dermis grafts are useful and versatile tools to have in one’s surgical armamentarium. A thorough understanding of the basic science of wound and graft healing, particularly how the grafts serve as scaffolds for new tissue ingrowth, enhances the ability to use these grafts more effectively. Although still very useful in wound healing, additional applications of acellular dermis grafts including tendon repair, ligament reconstruction, soft tissue supplementation and joint resurfacing should be given due consideration in surgical planning to optimize patient outcomes.

   Dr. Branch is in private practice with several offices in the Atlanta area. He is board certified in both foot surgery and reconstructive rearfoot and ankle surgery.

References
1. Beniker D, McQuillan D, Livesey S, et al. The use of acellular dermal matrix as a scaffold for periosteum replacement. Orthopedics. 2003; 26(5):591-6.

2. Barber FA, McGarry JE, Herbert MA. A biomechanical study of Achilles tendon repair augmentation using GraftJacket® matrix. Foot and Ankle International. 23(4):329-33, 2008.

3. Liden BA, Simmons M. Histologic evaluation of a 6-month GraftJacket® matrix biopsy used for Achilles tendon augmentation. J Amer Pod Med Assoc. 2009; 99(2):104-7.

4. Brady C. Ankle stabilization surgical technique using the split peroneus longus tendon (surgical protocol). Available at
http://www.biomet.com/sportsmedicine/getfile.cfm?id=2438&rt=inline .

5. Lee MS. GraftJacket augmentation of chronic Achilles tendon ruptures. Orthopedics. 2004; 27(1 Suppl):s151-3.

6. Weil LJ, Kurvilla B, Bergman D, Cain JD,Fridman R. The use of Pegasus OrthoAdapt™ Bioimplant in lateral ankle stabilization surgery. Available at http://www.weil4feet.com .

7. Grove JR, Hardy MA. Autograft, allograft, and xenograft options in the treatment of neglected Achilles tendon ruptures: A historical review with illustration of surgical repair. Foot Ankle J. 2008; 1(5):1.

8. Kummer FJ, Iesaka K. The role of graft materials in suture augmentation for tendon repairs and reattachment. J Biomed Mater Res B Appl Biomater. 2005; 74(2):789-91.

9. Malcarney HI, Bonar F, Murrell GA. Early inflammatory reaction after rotator cuff repair with porcine small intestine submucosal implant. Am J Sports Med. 2005; 33(6):907-911.

10. Roukis TS, Kovacevich LC. Foreign body reaction to a xenograft biological tissue scaffold and concominant infection: a report of two cases. Poster presentation at the Meeting of the American College of Foot and Ankle Surgeons, 2007.

11. Berlett GC, Hyer CF, Lee TF, et al. Interpositional arthroplasty of the first MTP joint using a regenerative tissue matrix for the treatment of advanced hallux rigidus. Foot Ankle. 2008; 29(1):10-21.

12. Branch JP. A tendon graft weave using an acellular dermal matrix for repair of the achilles tendon and other foot and ankle tendons. J Foot and Ankle Surg. 2011; 50 (2):242–250.

13. Coons DA, Barber FA. Tendon graft substitutes – Rotator cuff patches. Sports Med Arthrosc Rev. 2006; 14(3):185-90.

14. Malcarney HI, Bonar F, Murrell GA. Early inflammatory reaction after rotator cuff repair with porcine small intestine submucosal implant. Am J Sports Med. 2005; 33(6):907-911.

15. DeFranzo AJ, Argenta LC, Marks MW, Molnar JA, David LR, Webb LX, Ward LX, Ward WG, Teasdall RG. The use of vacuum-assisted closure therapy for the treatment of lower-extremity wounds with exposed bone. Plast Reconstr Surg. 2001; 108(5):1184-91.

16. DeLange MY, Schaasfoort RA, Obdeijn MC, van Der Werff JFA, Nicolai JPA. Vacuum-assisted closure: indications and clinical experience. Eur J Plast Surg. 2000; 23(4):178-82.

17. Repta R, Ford R, Hoberman L, Rechner B. The use of negative-pressure therapy and skin grafting in the treatment of soft tissue defects over the Achilles tendon. Ann Plast Surg. 2005; 55(4):367-70.

18. Barber FA, Herbert MA, Coons DA. Tendon augmentation grafts: biomechanical loads and failure patterns. Arthroscopy. 2006; 22(5):534-8.

19. Brigido SA, Schwartz E, Barnett l, McCarroll RE. Reconstruction of the diseased Achilles tendon using an acellular human dermal graft followed by early mobilization – A preliminary series. Tech Foot Ankle Surg. 2007; 6(4):249-253.

20. Lee DK. Achilles tendon repair with acellular tissue graft augmentation in neglected ruptures. J Foot and Ankle Surg. 2007; 46(6):451-5.

21. Stewart K. Review and comparison of current trends in postoperative management of tendon repair. Hand Clinics. 1991; 7(3):447-59.

22. Thompson RV. An evaluation of flexor tendon grafting. Br J Plast Surg. 1967; 20(1):121-44.

23. Rocchio TM. Atrophic plantar fat pad augmentation with acellular dermal graft. Podiatry Management. 2008; 10:175-84.

24. American Podiatric Medical Association. APMA Coding Manual. http://www.apmacodingrc.com . Accessed Nov. 21, 2012.

25. Cahaba Government Benefit Administrators, LLC Website – http://www.cahabagba.com.

Additional References

26. Colville MR. Surgical treatment of the unstable ankle. J Am Acad Orthop Surg. 1998; 6(6):368–77.

27. Kilkelly F, McHale K. Acute rupture of the peroneal longus tendon in a runner: a case report and review of the literature. Foot Ankle. 1994; 15(10):567-9.

28. Baer GS, Harner CD. Clinical outcomes of allograft versus autograft in anterior cruciate ligament reconstruction. Clin Sports Med. 2007; 26(4):661-681.

29. 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(4):1195-8.

30. Rocchio TM. Augmentation of atrophic plantar soft tissue with an acellular dermal allograft: a series review. Clin Podiatr Med Surg. 2009; 26(4):545-57.

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