Biologic scaffolding offers promise, concern for repairing rotator cuff tears
Surgical repair of large and massive rotator cuff tears results in satisfactory pain relief and improved function. Although the retear rate is high, patients with healed tears tend to be stronger and have better results.
In order to avoid the incidence of retears and other complications in rotator cuff repair, we are all seeking a biological scaffold that will act a as a stimulus to recruit host cells and improve healing of the native rotator cuff. This should lead to better results.
Another potential area for allograft use is the patient undergoing revision shoulder arthroplasty with a potential or real instability due to an inadequate subscapularis muscle tendon unit.
I have gathered together four orthopedists to discuss using xenograft and human acellular allograft dermal allograft for rotator cuff repair and to share their opinions and expereinces with this new technology.
James C. Esch, MD
James C. Esch, MD: Do you currently use an allograft for open or arthroscopic surgery, and if so, what are your indications for its use in shoulder surgery?
Stephen S. Burkhart, MD: I have limited experience in using allograft for arthroscopic glenoid resurfacing in young active people with chondrolysis and resulting degenerative arthritis of the shoulder, who are not candidates for shoulder arthroplasty.
Leesa M. Galatz, MD: I do not use allograft or xenograft material for open or arthroscopic rotator cuff repair.
Stephen J. Snyder, MD: I have never used an allograft for an open surgery. I started using the GraftJacket Human Acellular Dermal Allograft (GJA) (Wright Medical) arthroscopically 4 years ago and at that time was unsure if it would be successful. Because the patients had such devastating problems in the shoulder, I felt it was crucial to avoid causing any more problems by opening the deltoid.
I now use the GJA for complete replacement or bridging of a massive, retracted, nonreparable rotator cuff tear. I avoid patients with significant arthritis and medical problems, and so far have tried to limit the age to a maximum of around 60 years. I worry about the potential of older patients to repopulate the allograft matrix with viable mesenchymal stem cells. Most, but not all patients have had several failed previous surgical procedures.
Kenneth R. Zaslav, MD: I have used xenograft as an augmentation in some open shoulder surgeries with chronic cuff tears and other open tendon injuries with significant tendon deficiency, such as quadriceps, patellar tendon and chronic Achilles tendon reconstruction.
I have reserved the use of augmentation graft to situations where there is poor tendon quality and significant retraction, but where tendon ends can still be approximated.
Most xenografts are not approved for use as tissue replacement at this time. I have avoided using these in virgin cuff repairs arthroscopically up to this point because I am waiting for results to prove that the increased expense and time is clinically worthwhile, and that the grafts will result in a stronger, more viable repair. This has not yet been proven, but prospective clinical studies are ongoing.
Esch: Dr. Galatz, why dont you use these tissues?
Galatz: Several animal studies that have been performed with these products that have shown favorable results. These form the basis and the motivation for transferring their use to human beings. However, humans have several issues which separate them from these animal models. The animal studies are generally performed on young, healthy animals that will heal well regardless of the use of a patch or not. The rotator cuff tears that present a healing problem in humans are chronic tears in older people. The biology of these tendons is remarkably different from smaller and medium sized tears which generally heal quite well with modern repair techniques and careful postoperative rehabilitation. In addition, muscle atrophy and fatty infiltration at this point in time are irreversible, and have a significant correlation with failure of healing.
Importantly, clinical studies in humans have not demonstrated improved healing or improved functional outcomes with the use of extracellular matrix products. In fact, some studies have demonstrated adverse effects with the use of some patches.
In one study of small intestine submucosa (SIS) patches, 10 of 11 large or massive tears augmented with this product failed. Another prospective, randomized, controlled trial using SIS demonstrated a 7% greater chance of healing without the patch compared to augmented repairs.
A third prospective trial using SIS showed equal recurrence rates in patients 2 years after surgery in augmented and repairs without augmentation, with worse pain scores and decreased shoulder strength in patients that had the patch.
There are currently no published studies in the literature of xenograft dermis derived products in the shoulder. One study of xenograft dermis for use as interposition arthroplasty in the hand showed detrimental results. The patients had greater pain and histologic specimens showed foreign body reactions after removal. There are no basic science, animal or clinical studies published in the peer-reviewed literature on equine pericardium materials as an augmentation device in the shoulder.
Images: Synder SJ
One prospective series (not et published) using human derived dermal patch showed improved results after cuff repair using it as an interposition, rather than augmentation device. The majority of patients were satisfied. MRI studies 1 year after surgery suggested graft incorporation. However, there was no control group in this study. Fascia lata has typically been well tolerated in other locations for soft tissue reinforcement, but there are no studies showing efficacy in the shoulder for rotator cuff tears.
It is a huge leap to go from the bench top to the operating room. Before these products are recommended for routine use, I think the responsibility is on us as surgeons and researchers to establish efficacy. Given the considerable expense of these products and our emphasis on evidence-based medicine, routine use of these products has not been substantiated, and their use should still be considered experimental.
Esch: In terms of using an allograft for rotator cuff surgery, what are your technique and experiences with these materials, either open or arthroscopic?
Burkhart: I have not used an allograft for rotator cuff surgery. I have found that I can repair native rotator cuff tendon directly to bone in greater than 97% of all cases, even in massive retracted tears. However, these tears typically require mobilization by means of a single-or-double interval slide in order to achieve sufficient lateral excursion of the tendon for direct repair to the bone. In the 3% of cases that are not fully reparable, I do a partial rotator cuff repair in which I repair all the tendon that will easily reach the bone bed.
Snyder: I have performed 48 arthroscopic GJA rotator cuff replacements in the last 4 years. Initially, the surgery was confusing and time-consuming, taking up to 4 hours in some cases. We practiced the technique numerous times in the lab and OR using the Alex model with the entire team before the first attempt.
After training, my team averages 2½ hours per case, and I am sure that time will improve as it did in ACL or rotator cuff procedures in the early days of arthroscopy.
Esch: What is your preferred allograft material, and why?
Zaslav: I prefer the OrthAdapt implant (Pegasus Biologics). This implant of sterile equine pericardium has excellent handling properties, it is easy to sew to and manipulate. More importantly there have been several patented improvements in the preparation of this implant to enable it to be bioavailable as a structural augmentation when it is needed most, at 6 to 18 weeks postop during early active mobilization of the cuff repair.
Dr. Joseph Iannottis landmark study on the use of xenograft augmentation in chronic rotator cuff tears showed that porcine implants are not biomechanically available at the time they are needed most. This is most likely due to enzymatic breakdown due to collagenases and weakness produced in the sterilization processes.
The xenograft may be strong biomechanically at time of the manufacture; however, his study clearly shows that the previous constructs failed when they were needed most.
The OrthAdapt patch is crosslinked with an ethyldiethylaminopropylcarbodiimide (EDC) (a water-soluble coupling agent)-enhanced chemical process, which maintains the distance between the collagen helices while yielding a structure that is resistant to early enzymatic breakdown by collagenase.
Secondly, once you crosslink the implant, you need to sterilize it in a fashion that also does not weaken the collagen integrity.
Pegasus has developed a patented technology that allows you to sterilize with EDC with no ultimate loss of ultrastructural or biomechanical strength. In the end, this implant has the potential to overcome the problems Iannotti found. Due to its variable crosslinking, it can be bio-available and mechanically available not only at the time of implantation but also at the time it is needed most at 6 to 12 weeks postop.
Burkhart: For glenoid resurfacing, I have used GJA. I do not have experience with any other allograft materials for this operation.
Snyder: I only have experience using GJA. I considered using the other materials, but I am convinced that using an acelluar human allograft tissue that surgeons have used for soft tissue surgical repair for more than 10 years is the safest and most reliable choice available. Since the GJA is an allograft, I compare it in many ways to the choice of grafting tissues preferred in knee ligament surgery, where essentially no xenograft tissue has proven safe or reliable. The GJA in its 2-mm-thick configuration is strong, but being somewhat elastic in nature, it resists suture cutout during the critical repopulation period.
Canine studies have shown excellent integration of the GJA into the surrounding tissues without any significant signs of rejection or chronic inflammation.
In vitro studies have also confirmed the strength and cellular compatible properties of acellular human dermagrafts exhibited in in vivo studies. I have never heard of a case of graft rejection or viral disease transfer using this tissue, and my experience has only added to my comfort level.
Esch: What is your experience with your preferred material?
Zaslav: I have used OrthAdapt both in mini-open rotator cuff revision surgery and patellar tendon repairs. I believe it may also be useful as a substitute for periosteum in articular cartilage implantation (ACI) procedures when adequate periosteum is not available locally. This is currently an off-label use, but one that we are investigating and has shown promise. An earlier British prospective 2-year study with a different xenograft product showed equal results to periosteum with less postop periosteal hypertrophy. We are beginning a trial for this use.
Burkhart: My experience in six patients for glenoid resurfacing is that four of them are doing extremely well at 1.5 year average follow-up, with full motion and little or no pain. The other 2 have persistent pain that is slightly better than their pre-op pain.
Snyder: I have performed 48 arthroscopic replacement operations using GJA. So far, 8 cases have failed by tearing on the 3-month MRI (one possible infection), and an additional one failed at 11 months. Three of the failures were in cases where I used the thin (1 mm) graft material before the 2 mm was available. We have 16 cases with more than 2 years of follow-up. Two of the early failures were traumatic. I have successfully repaired two of the failures with repeat operations and reattached a portion of the torn tendon to the bone.
Two of the attempted repairs did not heal, but the patients are better functionally and clinically. One patient is worse, even with an intact graft at 2 years postop.
Esch: Has infection or sterile surgical drainage been a problem?
Zaslav: There have been no known reports of this with this xenograft implant yet.
Snyder: I have had one case of suspected infection in a 56-year-old female on immunosuppression drugs for chronic liver disease. She had a slight increase in C-reactive protein at 1-week postop and slight drainage from her anterior portal.
I rescoped her shoulder and the graft looked fine; all cultures were negative. She had a 10-week course of antibiotics, but the 3-month MRI revealed that the graft failed. In retrospect, she was not a good candidate because she had failed several previous operations on both shoulders and was severely incapacitated.
Esch: In my community, one of these tissue allografts costs at least $2,500 and is usually not reimbursed by insurance carriers, especially in the outpatient setting. What is your approach for reimbursement for these materials?
Zaslav: I believe this is still a major problem and one which currently keeps most of us from using these regularly for routine chronic cuff tears. I think we need better prospective randomized data before suggesting this added cost.
Snyder: Since I perform all my surgery in an outpatient surgery center, I cannot ask them to be at risk for the cost of the graft. I have chosen to make a contract with the insurance company and the patient preop to guarantee payment for the cost of the graft with no mark-up. Lately, the surgery center has been using a third-party billing service to avoid the risk of non-payment. It seems to be successful.
Images: Zaslav KR
For more information:
- James C. Esch, MD, can be reached at Tri-City Orthopaedics, 3905 Waring Road, Oceanside, CA 92056-4405; 760-724-9000 e-mail: email@example.com. He receives royalties from Breg and is a consultant for Smith & Nephew Endoscopy, Wright Medical and KFx Medical.
- Stephen S. Burkhart, MD, can be reached at The Orthopaedic Institute, 400 Concord Plaza Drive, Suite 300, San Antonio, TX 78216; 210-489-7220; e-mail: firstname.lastname@example.org. He receives royalties and is a consultant for Arthrex, Inc.
- Leesa M. Galatz, MD, can be reached at Washington University Orthopedics, One Barnes-Jewish Hospital Plaza, Suite 11300, West Pavilion, Saint Louis, MO 63110; 314-747-2813; e-mail: email@example.com. She has no direct financial interest in the products or companies mentioned in this article.
- Stephen J. Snyder, MD, can be reached at the Southern California Orthopedic Institute, 6815 Nobel Ave., Van Nuys, CA 91405; 818-901-6600; e-mail: firstname.lastname@example.org. He is a consultant for Wright Medical Technology and received royalties for some rotator cuff allograft products.
- Kenneth R. Zaslav, MD, can be reached at Advanced Orthopedic Center, 7858 Shrader Road, Richmond, VA 23294; 800-966-1718; e-mail: email@example.com. He is a member of the scientific advisory board for Pegasus Biologics and Genzyme Biosurgery.