By way of background, I performed eight autologous hamstring resurfacing arthroplasties during the later half of 2007 at Franklin Regional Medical Center. This procedure involves harvesting the gracilis and semitendinosus tendons and rigidly oppossing them to the medial femoral condyle using knotless absorbable bone anchors for fixation. The drill holes for the bone anchors serve as a source for hematopoetic marrow elements and a blood supply to allow the tendon to biologically heal to the subchondral surface. This procedure combines two established surgical approaches (soft tissue resurfacing arthroplasty and enhanced microfracture technique) each of which is published and used in orthopaedics.
This technique is most similar to the Geistlich AMIC surgical technique guide (see power point tutorial), chondrotissue guide, and the ASEED® technique, except that instead of using the artificial scaffolds (which are available in Europe but are "off label" in the USA), I used autogenous hamstring tendons to serve as a collagen scaffold, recognizing the well documented ability of tendons to differentiate into fibrocartilage. (references for tendon metaplasia). Otherwise these procedures are essentially the same. Currently in Europe, the chondro gide patch is used along with the enhanced microfracture technique, and according to Geistlich, this procedure has become very popular and well accepted. (5000th Chondro-Gide® implanted - 2009 News letter page 12)
There is a growing number of older patients with osteoarthritis (OA) of the knees that have failed non operative treatment (injections, anti-inflammatories, canes, and narcotics) and as a result have chronic pain that limits activities of daily living (cooking, cleaning, simple shopping) and limits the quality of their lives. Often these patients report that the main area of pain centers around the medial femoral condyle and this is what drives them to surgery.
There is a subgroup of these patients that cannot have - or do not want - a total or partial joint replacement (TJR). These patients note that they either do not want a TJR because of their health, because of the risks associated with surgery, or because they are unwilling to perform the necessary postoperative therapy. What some of these patients are asking for, is a simple surgery that gives them some pain relief (perhaps 30-50%) without the comorbidity of a knee replacement.
Specific patient examples in my practice include a cancer patient with an uncertain future, a fragile rheumatoid on immunosupressives, and a patient who had a knee replacement by another orthopaedic surgeon which had a poor outcome due to arthrofibrosis. These patients each had OA in one or both knees and were intimidated by the potential surgical complications, and all expressed a strong concern over infection. Certainly, the rising incidence of MRSA (methacillin resistant staph aureus) joint infections has added to the public's concern about joint replacement (70% of staph auereus is now MRSA). When a patient gets an MRSA total joint infection, there is a requirement for
additional surgery and often a poor outcome. In the small subset of patients that I have described, a total joint infection would clearly have disrupted their lives far above that of the average patient.
Between 2006 and 2007, I have had three patients that developed MRSA infections (two from total joints and one from a rotator cuff) which caused poor outcomes in each of these patients. What was most concerning was that we did not know the source of these infections at that time. Indeed, even our own academy has weighed in on the MRSA issue (The silent epidemic: CA-MRSA and HA-MRSA and Infection after TKA: An unsolved problem) As noted by Dr Berry in the later article, "An extremely strong correlation exists between how sick the patient was and the likelihood of both early and late infection developing in that patient." Many orthopaedic surgeons have already suspected this causal relationship, and many would not be suprised by findings from a recent AAOS podium presentation that found a 40.6% surgical complication rate, a 14.3% medical complication rate (2 deaths out of 105 patients), and a 14.3% reoperation rate in superobese patients. It was for these same reasons that I became motivated to look for surgical alternatives for comorbid patients that needed surgical intervention but could not bear the risk of infection (along with other complications).
Where as, in the recent past it was standard of care to offer osteoarthritic patients an arthroscopic debridement as an alternative to replacement, the arthroscopic debridement option has been discredited after two landmark New England Journal of Medicine Articles (Moseley) and Kirkley) and a recent AAOS position statement. Hence, any surgical alternative for these patients needs to be more than a simple knee arthroscopy and less than a metalic resurfacing arthroplasty. Further, I think that many orthopaedic surgeons emotionally felt good about arthroscopic debridement simply because it was an option other than replacement.
I would wager that this same group of surgeons looks forward to the day when there is again a viable surgical option other than replacement.
I collected and reviewed the literature on soft tissue resurfacing arthroplasty for both knees and shoulders (Krishnan , Ochi, Oztuna , Schuck,
Jaberi , Johnson), numerous periosteal grafing studies, as well as a substantial amount of literature on "enhanced microfracture" using collagen scaffolds. What is clear from this review is that whatever name is given to these procedures (soft tissue resurfacing, periosteal grafting, or AMIC), it is undeniable that there are over one hundred research studies that demonstrate that whenever you surgically connect a collagen membrane to an area of damaged cartilage, there is a positive biologic effect which promotes cartilage regeneration (or fibrocartilage regeneration). This concept has been validated with basic science studies, animal studies, and through clinical trials, and the concept was mentioned in the latest 2009 AAOS cartilage restoration review (supplemental barrier implantation) as well as in 3 recent textbooks, Cartilage Repair Strategies (p 72), Biologic Joint Reconstruction (p 767), and Fundamentals of Tissue Engineering and Regenerative Medicine (p 234).
Currently, there are almost as many papers discussing enhanced types of microfracture (with various types of collagen scaffolds) as simple microfracture articles. The idea is that the overlying collagen scaffold will help protect and facilitate maturation of the underlying pluripotential marrow elements which are developing out the microfracture drill holes. A number of scaffolds (for microfracture) are under research investigation which are showing great promise (such as chitosan-glycerol phosphate/blood implant, Chondro-Gide, Chondrotissue and ASEED® technique), but none of these are currently "on label approved" for knee chondral injuries with microfracture in the US. (Of note Chondro-Gide® is available for use with microfracture in Europe and Australia, and the chondrotissue guide is available throughout Europe and is now available in Canada (www.cartilagetissue.com)) See power point slide show).
There are also a number of scaffolds available for ACI but this type of procedure would be "off label" for frank osteoarthritis. Some examples of these scaffolds include neocart, regen, cell mix, Matricel, Hyalograft C graft, composite PLA-PGA polymer fleece) Again these types of scaffolds would be off label (and would not be covered by insurance) for the subgroup of patients I am describing. In order to address the needs of my subset of patients, I believed that the medial hamstring tendons could serve as an appropriate collagen scaffold over a microfracture bed using bioabsorable anchors to provide graft fixation as well as the drill holes for the microfracture. I believed that the results would be at least similar to the standard microfracture and could possibly be better than average with a protective collagen scaffold. We know the complications of hamstring harvest are minimal and that these hamstring tendons have given consistently good results for ligament reconstruction as well as interpositional arthroplasty in other areas of the body (Voellmicke, Coughlin, Miller, Baumhauer, Sizensky).
In an interesting comparison with hallux rigidus, Coughlin in 2003 used the gracilis tendon (medial hamstring) for a series on interpositional arthroplasties in hallux rigidus (great toe arthritis) which gave strong clinical results. Then in 2008, the same authors published another report (FAI 2008 Jan), in which they used "a human acellular dermal regenerative tissue matrix as a spacer" in another group of hallux rigidus patients. The authors again noted strong clinical results, and it seems logical that they started with a gold standard technique (autologous hamstrings as an interpositional spacer) and then went on to a foreign body type collagen matrix to serve as an interpositional spacer.
My main contention is that for the purposes of my subset of patients, autologous hamstring tendons would also stand as the most conservative gold standard (as the collagen scaffold) and where as the other commercially available scaffolds would be seen as more unpredictable. In terms of basic science we know that tendons do have the ability to adapt to form fibrocartilage when subjected to compression (see Tendon Metaplasia to Cartilage) which might indicate that there is an additional advantage of autogenous tendons over commercial scaffolds. (It may turn out that this type of metaplasia is an integral part of healing of tendon to bone such as in ACL reconstruction) (ref). As has been mentioned, the autogenous living tendon is already seeded with tenocyte cells that are preprogramed to transform into fibrocartilage when subjected to compressive loads against an osseous surface. Hence in this case, we are attempting to use an autogenous collagen scaffold for microfracture rather than a commercial scaffold (which would be off label or available only through FDA trials).
Prior to the acceptance of total joint replacement in the 1970s and 1980's, there was an interest in soft tissue resurfacing arthroplasty for arthritic knees. Where as the acceptance of soft tissue resurfacing arthroplasty has waned, it has continued to be well accepted for small joints. Recently, however, there has been a renewed interest in soft tissue resurfacing arthroplasty for knees and shoulders (Slynarski, Krishnan, Ochi, Oztuna, Schuck, Jaberi, Johnson) using allograft, meniscus, periosteum, quadriceps, and tensor fascia lata and these studies attest to the safety of these approaches and well as strong clinical results. It may turn out the ability of tendons to transform into fibrocartilage (metaplasia) explains the success of these procedures. The use of a hamstring resurfacing procedure is using elements of resurfacing procedures and the enhanced microfracture procedures inorder to obtain a cartilage like surface bonded to the underlying subchondral bone. These procedures should not be considered separate but are really synergistic as has be described by (Zhang). In short, this procedure is trying to provide a stable collagen covering over a stimulated (surgically drilled) subchondral surface (Jakob and McNickle.
I felt that my small comorbid group of patients could be helped with this technique while minimizing or avoiding the complications seen with TKR, namely, pulmonary embolus, arthrofibrosis, flexion instability, periprosthetic fracture, component malalignment, component aseptic loosening, osteolysis, as well as periprosthetic infection. Just as important, after several months, these patients could continue to receive injection therapy when needed (steroids and synvisc) which are contraindicated with metal resurfacing procedures. In addition, "no bridges would be burned" if joint replacement would be require at a later time.
In terms of results, I have had to revise two patients to total joint replacement (both had excellent results), one has been lost to follow up, and five patients (six knees) have continued to function well enough to avoid knee replacements (which otherwise would have been required).
I was extremely careful to explain the relative risks and benefits of the patient's comorbidities and to educate them thoroughly as to the nature of the procedure. They understood that the likelihood of positive results (beyond a standard arthroscopy) would be somewhat unpredictable, but it was unlikely that this procedure would make them worse. In every case, I discussed the problem with my partner Dr. Galland, and gave the patients the opportunity to see him for a second opinion. In short, the informed consent process was absolutely complete.
Furthermore, before performing the procedure, I utilized every resource available to me in order to ensure that I followed all guidelines. In this procedure, there is certainly nothing new (tendon resurfacing arthroplasty and enhanced microfracture in the knee have been well published), but I did recognize that this technique was different in that I was using the hamstring tendon (instead of the more traditional quadriceps or fascia lata or commercial scaffold) and was different in that these patients had frank osteoarthritis rather than a simple chondral injury. Because of this difference, I discussed this procedure with the HMA corporate legal department, the HMA corporate research nurse, my malpractice carrier, the chief of joint replacement at Duke University Medical Center, an ad hoc committe at Franklin Regional Medical Center (one of the surgeons was a former UNC assistant professor), the medical executive committe, and finally the board of directors. These governing bodies all approved the procedure, and agreed that I was not performing research but rather trying to offer surgical alternatives to patients in special circumstances who did not want joint replacement and whose lives would be severly disrupted if they were to get a joint infection.
The philosophies of one age have become the absurdities of the next, and the foolishness of yesterday has become the wisdom of tomorrow.