A Closer Look At Orthobiologics For Tendon Repair
The use of orthobiologics may facilitate enhanced tendon repair and minimize or eliminate common complications. Accordingly, these authors provide a step-by-step guide to the use of two orthobiologics and how they contribute to optimal outcomes.
Tendon surgery is one of the most challenging paradigms for the podiatric surgeon. Whether the tendon injury is acute or chronic, the repair is based on a few simple parameters. These parameters include early range of motion, restoring the length-tension balance, restoration of the simple gliding mechanism associated with the tendon and, of course, adequate strength of the repair.
Unfortunately, if one does not meet all the parameters, the patient will have an undesirable result and an inevitable future rupture, injury and/or continued pain. For some time after repair of the tendon, the body relies simply on the suture that the surgeon used to satisfy all of the aforementioned parameters. That is to say, the weakest link of the repair is often the type of suture the surgeon uses for the repair and/or the stitch technique he or she uses to facilitate the repair.
One of the most exciting areas of science and medicine is the advent of orthobiologics. By definition, orthobiology is the inclusion of biology and biochemistry in the development of bone and soft tissue replacement materials for skeletal and tissue healing. With the advent of orthobiologics, the surgeon has a number of options for increasing the strength and ability of the repair while decreasing the length of the postoperative period.
Accordingly, let us take a closer look at a couple of the major biologics surgeons use in tendon repair and effective techniques for use. This article is not all-inclusive as we will focus on our experience with Restore® (Depuy) and GraftJacket® (Wright Medical).
Examining The Benefits Of Restore
Restore is porcine-derived small intestine submucosa (SIS). It is a resorbable, 10-ply, isotropic-designed extracellular matrix (ECM), which provides a scaffold conducive for quick remodeling. It is a non-cross-linked implant surgeons can use for reinforcement of weakened and/or damaged soft tissue.
The implant is specifically intended for reinforcement of the soft tissues, which one repairs via suture or suture anchors. It is designed to provide a resorbable scaffold, which is gradually replaced by the body’s own soft tissue. It attracts host cell migration, resulting in a tissue that is structurally and functionally similar to the original host tissue. However, it is not intended to replace normal body structure or provide full mechanical strength.
In regard to the soft tissue wound healing and remodeling response that occurs after implantation of the Restore orthobiologic implant, the surgeon should expect to see signs of active proliferation of responding cells and blood vessels (angiogenesis) at the repair site approximately two to four weeks postoperatively. Sometimes the cellular response may manifest in localized redness, swelling and warmth. If the patient has this angiofibrous proliferative response, it should resolve within four to six weeks postoperatively. Restore is contraindicated in patients with allergies to pork or pork products
One can use Restore to augment a posterior tibial tendon intrasubstance repair. The repair begins with dissection down to the flexor retinaculum. Tag the retinaculum by using a non-absorbable suture for later identification and repair. Then incise the tendon with a scalpel at the area of the intrasubstance tear. After identifying any tendon degeneration, which manifests by thickening and fibrosis, repair the regeneration by first shelling out the pathology in a longitudinal fashion. In the effort of promoting angiogenesis, lightly curette the remaining tendon.
The surgeon proceeds to use the suture of choice (generally a long absorbing or non-absorbing braided suture) to tubularize the tendon in order to facilitate a strong and anatomically sized construct. Finally, wrap the Restore around the tendon and sew it upon itself to augment the repair and cover the sutures. Then rotate the Restore on its long axis so the sutures that hold the Restore in place are facing inward. Once this is in place, suture the Restore to the tendon with one stitch proximally and one stitch distally. When it comes to subsequent repair of the flexor retinaculum, one can usually use a high gauge vicryl.
Preserving Gliding Mechanisms For Tendons
Another excellent use for Restore is when simple gliding mechanisms for a tendon are violated. One patient underwent an implant arthroplasty of the great toe joint. Unfortunately, the patient was non-adherent with early range of motion and, as a result, the extensor tendon became bound down to the overlying skin and the toe maintained an elevated posture.
The surgeon subsequently performed a tenolysis. However, intraoperatively, there was a concern that the tendon would scar back to the overlying subcutaneous tissue and a similar result would occur. Therefore, the surgeon used Restore to delicately preserve the gliding of the extensor hallucis longus tendon sheath.
Pertinent Insights On Using GraftJacket
When it comes to more extensive intrasubstance tears and complete ruptures, our orthobiologic of choice is GraftJacket, an acellular dermal matrix derived from human cadaveric skin. It undergoes a proprietary process that renders it totally unrecognizable by the body’s immune system. It consists of collagen and extracellular protein matrices. Revascularization is possible due to the scaffold, which is composed of elastin, collagen, proteoglycans and preserved blood vessel channels.
The regenerative nature of GraftJacket allows it to “disappear” into the host tissues over time instead of leaving a foreign graft in the body. Histologically, GraftJacket is indistinguishable from surrounding host tissues. Simply stated, the product assumes the characteristics of the tissue to which it adheres. The product comes in various sizes and thicknesses. Therefore, one can select a different size based on the strength needed for the repair and the size of the defect the surgeon is repairing.
Also bear in mind that GraftJacket is double-sided so one can place the “non-biologic side” or “gliding” side away from the repair. This will facilitate and preserve gliding of the tendon against the retinaculum or overlying subcutaneous tissues.
GraftJacket has proven to be an integral part of the podiatric surgeon’s armamentarium in wound repair, ligament repair and fat pad restoration. Recently, there have been significant advances in using GraftJacket for tendon repair/augmentation and cartilage resurfacing.
Although the entire technique of cartilage resurfacing is beyond the scope of this article, it is important to note that in certain instances, such as first metatarsophalangeal joint (MPJ) resurfacing, GraftJacket offers an excellent means of restoring the gliding motion of the flexor hallucis brevis/sesamoid complex. In the process of using GraftJacket for first MPJ cartilage resurfacing, one of the paramount events is histologic evidence of chondrocytes evident in first metatarsal biopsy. However, equally as important is the gliding mechanism of the sesamoidal flexor hallucis brevis tendon amalgamation.
The biggest fault in the pathomechanics of hallux limitus/rigidus is when the flexor tendon and sesamoids bind to the first metatarsal. When performing a first metatarsal resurfacing, one uses a McGlamry elevator to separate the bound sesamoids from the first metatarsal. Unfortunately, due to denuded cartilage on the sesamoids and the first metatarsal, the sesamoids will rebind to the metatarsal in a few short weeks. However, interposing GraftJacket into this complex with the non-biologic side against the sesamoid-flexor apparatus preserves the gliding mechanism and also preserves the motion of the sesamoids under the first metatarsal.
When it comes to complete tendon ruptures, GraftJacket has virtually eliminated the need for cadaveric tendon grafts. Even if the rupture is old, the surgeon has a new alternative that did not exist several years ago. In the previous treatment of ruptured tendons, the surgeon’s choices were as follows:
• transfer another tendon (which destabilized a different part of the foot); or
• use a cadaveric graft (which often came with an undesirable immune response).
If the surgeon performed a slide type lengthening, the tendon would inevitably weaken and the surgeon risked possible re-rupture.
With the advent of GraftJacket, the surgeon has new choices. He or she has the opportunity to perform a slide-type lengthening of the tendon and augment the repair with the GraftJacket, or substitute GraftJacket as an interpositional graft in lieu of the cadaveric tendon. In either event, repairing the tendon with GraftJacket facilitates exceptional strength, preservation of length, no immune response and anatomic restoration.
Case Study: When A Patient Has A Ruptured Achilles Tendon
In the following example, a 34-year-old male ruptured his Achilles tendon playing football.
The surgeon made an incision over the Achilles tendon. The tendon was gapped significantly with necrosis of the ruptured ends. The surgeon debrided the necrotic tendon and performed a direct repair using a Krackow stitch. The surgeon proceeded to use a 4x7 cm GraftJacket MaxForce (the thickest and strongest version of GraftJacket) to encompass and augment the direct repair. Plantarflexing the ankle and suturing the MaxForce under tension facilitates this repair.
The patient wore a cast in gravity equinus. The convalescence period was unremarkable for approximately three weeks. Against medical advice, the patient removed his own cast and subsequently slipped on his child’s toy. The tendon re-ruptured and required a second repair. Interestingly, upon surgical examination, the GraftJacket had fully incorporated at three weeks and was holding the ruptured ends in place and full tension (even though the intrasubstance of the tendon was completely torn).
The surgeon obtained a biopsy of the tendon with the incorporated GraftJacket. Upon histologic examination, the biopsy showed full incorporation of the graft. Moreover, the GraftJacket was indistinguishable from the Achilles tendon for which it was grafted. Upon subsequent repair, the patient made a full recovery.
The advent of orthobiologics has obviated the result of some of the most complicating factors in the repair of tendons. With the use of Restore and GraftJacket, surgeons are now able to avoid the major reactions associated with allografts and autografts. One can restore mechanical function faster with virtually no risk of host rejection. These orthobiologics facilitate enhanced strength and stability, which are paramount to the repair. Surgeons can also preserve the gliding mechanism of tendons and their sheaths.
All of these combined factors result in the patient’s improved result and return to function more quickly with ultimate remodeling of existing tissue being virtually indistinguishable from the original host tissue. In addition, these patients have been able to return to normal activity in less time with markedly reduced complications and restoration of normal function. Postoperatively, one must control or eliminate the underlying cause of tendon injury.
Dr. Troiano is affiliated with the Penn Wound Care Center and the Center for Foot and Ankle Disorders in Philadelphia. He is an Associate of the American College of Foot and Ankle Surgeons.
Dr. Schoenhaus is the Podiatric Medical Director of the Penn Wound Care Center in Philadelphia. He is a Fellow of the American College of Foot and Ankle Surgeons, and is board-certified by the American Board of Podiatric Surgery and the American Board of Podiatric Orthopaedics.