Can An Emerging Synthetic Graft Have An Impact In Soft Tissue Repair?

Author(s): 
Jason R. Miller, DPM, FACFAS, and Stanley Chen, DPM, AACFAS

Tendon and ligament pathologies are extremely common in the adult population. Eleven percent of runners experience Achilles tendinopathy with seven out of 100,000 people sustaining a rupture. There are 1 million ankle injuries per year, 85 percent of which are ankle sprains. The total cost of tendon and ligament treatment is approximately $30 billion per year in the United States alone.1 The medical community has actively sought the augmentation of these repairs and the response by orthobiologic companies has been great.

   There are two types of augmentation grafts, biologic and synthetic. Biologics have the advantage of being bioactive and creating induction of new tissue ingrowth at a faster rate.2,3 The disadvantages include low mechanical stamina often leading to structural failure; nonspecific induction leading to low quality tissue repair; an undefined degradation rate to assess healing time; and biocompatibility variations that may lead to rejection, and/or a significant inflammatory response.

   Synthetic grafts exhibit stronger mechanical strength and consistency in quality.4,5 Synthetic grafts are capable of acting as permanent replacement tissues in severely neglected repairs. The primary disadvantage may be poorer biocompatibility.

   Artelon (Artimplant) is a porous polyurethane urea, which performs as a scaffold allowing ingrowth of host tissue.6,7 This material has been in use in surgical procedures for over 30 years and more specifically in orthopedic type procedures for approximately 15 years. The implant maintains strength and elasticity over the long term to provide support. Artelon products retain approximately 50 percent of their strength after four years. They are designed to degrade over the course of five to seven years as the host tissue replaces the majority of the graft material.

   The applications of Artelon include joint resurfacing, tissue reinforcement and augmentation in tendon/ligament repairs. With Artelon being a biocompatible synthetic material, there is no risk of collagen rejection or disease transmission. Collagen patches have shown good initial strength but they degrade quickly and strength may not be maintained in the repair, which could lead to re-rupture.

   Artelon has properties that mimic tissue elasticity. With ingrowth of host tissue, the integrated implant will gradually take on more load, which is why it has been popular with general surgeons in hernia type of repairs.

A Closer Look At The Bioscaffold’s Indications And Usage

The intended use of this bioscaffold is reinforcement of soft tissue in which weakness is a concern. It is not intended to replace deficits in normal body structure or provide complete mechanical strength. The sutures surgeons use to repair a rupture or the ones they use with bone anchors provide the mechanical strength for tendon repair. Artelon reinforces the soft tissue in the repair and provides a biodegradable scaffold that incorporates into the patient’s native tissue. We have used porous polyurethane urea synthetic grafts for repairs in the following procedures.

• Achilles tendon repair
• Plantar plate repair
• Modified Brostrom lateral ankle reconstruction
• Painful os peroneum excision
• Peroneal tendon reconstruction
• Tibialis posterior tendon reconstruction
• Extensor hallucis longus repair
• Spring ligament repair/augmentation

   Contraindications include patients with active or latent infection, decreased vascularity or pathologic soft tissue disorders that would prevent secure attachment. It is also not advised to use the product in patients for whom rolling, layering or folding of the graft is required as it may lead to impermeability of fluid, cells and vascular ingrowth. This could potentially lead to excessive inflammation, drainage, extrusion and infection.

   Potential complications of the implant include infection, acute or chronic inflammation, tissue erosion and graft extrusion.

   The implant comes in patch form and is easy to handle and shape to the application once it is rehydrated in normal sterile saline solution. It is packaged sterile with a minimum dose 25 kGy electron beam radiation. The shelf life is five years. One can store the product at room temperature and normal relative humidity is advised. Prior to using the implant, one should submerge it into sterile saline at room temperature for at least five minutes. The senior author frequently hydrates the implant in platelet rich plasma as a substitute to the normal sterile saline solution for an equivalent timeframe.

Case Studies In The Use Of Artelon

A 57-year-old female presented eight weeks after dropping large scissors on her foot. She had a laceration and flexion contracture of the first metatarsophalangeal joint (MPJ) and hallux. The patient reported loss of push-off strength in normal gait. Surgeons retrieved the extensor hallucis longus tendon both proximally and distally with the proximal portion split longitudinally to span the defect. Surgeons then augmented repair with an Artelon strip, which was anchored at each end with non-absorbable suture and along its course with Vicryl (see photo at left). The patient went on to bear weight at four weeks and reported gradual increases in first MPJ dorsiflexory power after eight weeks during physical therapy.

   A 62-year-old squash player presented 10 weeks after injuring his Achilles tendon. Surgeons secured the Artelon patch proximally and distally with non-absorbable sutures while securing the graft to itself in a tubular fashion with Vicryl sutures, ensuring minimal to no overlap (see photo at right). The patient returned to full weightbearing at three to four weeks postoperatively and started full physical therapy by week six. After 12 weeks, the patient returned to reduced activity squash and by six months was competing again.

In Conclusion

The question remains as to whether graft augmentation precludes re-rupture. Key factors surrounding this issue include patient education, adequate physical rehabilitation, home exercise programs, a gradual return to activity, patient awareness of the injury severity, the postoperative course, and seeking early intervention if the patient recognizes any problems in the healing course.

   With the high incidence of degenerative and traumatic soft tissue injuries, biomaterial support is favorable. Synthetic scaffolds can provide excellent biocompatibility and predictable degradation. Scaffolds may augment soft tissue repairs in which weakness exists or even facilitate an earlier return to activity. Artelon allows for revascularization and supports repair through remodeling with satisfactory clinical outcomes. The use of synthetic graft to augment tendon and ligament repairs is showing promising results in our experience and further randomized prospective trials may yield further support of its applications.

   As always, one should employ caution when using any orthobiologic until there are more level 1 studies to support more universal use as the additional cost of these products should be justified by evidence-based studies. It is important, however, for the foot and ankle surgeon to be aware of what options are available should complications arise. Historically, if a patient has had sensitivity to allografts or xenografts in prior surgical procedures, the surgeon’s only choice in the past may have been an autograft harvest. With this synthetic graft’s ease of use and current safety profile, the need for host donor tendon/ligament harvests may be reduced.

   Dr. Miller is a partner of the Pennsylvania Orthopaedic Center and an Adjunct Associate Professor in the Department of Surgery at the Temple University School of Podiatric Medicine in Philadelphia. He is currently the Director of the Pennsylvania Intensive Lower Extremity Fellowship Program in Malvern, Pa. Dr. Miller is a Diplomate of the American Board of Podiatric Surgery. He is a Founding Fellow of the American Professional Wound Care Association.

   Dr. Chen is a Fellow with the Pennsylvania Intensive Lower Extremity Fellowship. He is an Associate of the American College of Foot and Ankle Surgeons.

References
1. Rees JD, Wills AM, Wolman RL. Current concepts in the management of tendon disorders. Rheumatology. 2006; 45(5):508-521.
2. Decarbo W, Feldner, B, Hyer, C. Inflammatory reaction to implanted equine pericardium xenograft. J Foot Ankle Surg. 2010; 49(2):155-58.
3. Chen J, Xu J, Wang A, Zheng M. Scaffolds for tendon and ligament repair: review of the efficacy of commercial products. Expert Rev Med Devices. 2009; 6(1):61-73.
4. Basiglini L, Iorio R, Vadala R, et al. Achilles tendon surgical revision with synthetic augmentation. Knee Surg Sports Traumatol Arthrosc. 2010; 18(5):644–647.
5. Valentin JE, Badylak JS, McCabe GP, Badylak SF. Extracellular matrix bioscaffolds for orthopaedic applications. a comparative histologic study. J Bone Joint Surg Am. 2006; 88(12):2673-2686.
6. Giza E, Frizzell L, Farac R, et al. Augmented tendon Achilles repair using a tissue reinforcement scaffold: A biomechanical study. Foot Ankle Int. 2011; 32(5):S545-549.
7. Artimplant product monograph and company correspondence, 2013. Available at http://www.artimplant.com/ .

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