Background:
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 oppossing them to the medial femoral condyle using knotless absorbable bone
anchors. 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 enchanced microfracture
technique) each of which is widely published and used in orthopaedics.
Discussion:
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) It was during this time that I was motivated to look for surgical
alternatives for comorbid patients that needed surgical intervention but could not bear the risk of infection. I was aware
of some recent articles on soft tissue resurfacing arthroplasty for both knees and shoulders (Krishnan , Oztuna , Schuck,
Jaberi , Johnson) as well as a substantial amount of literature on "enhanced microfracture" using collagen scaffolds.
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 collagen scaffolds (for microfracture) are under FDA investigation which are showing great promise (such as
chitosan-glycerol phosphate/blood implant), but none of these are currently available for the general public. (There are 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. 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).
There have been some recent papers on soft tissue resurfacing arthroplasty for knees and shoulders (Krishnan , Oztuna ,
Schuck , Jaberi , Johnson) using allograft, quadriceps, and tensor fascia lata and these studies attest to the safety of these
approaches and well as strong clinical results. This 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 (ref).
I felt that my small comorbid group of patients could be helped with this technique while not exposing them to the risks of
infection associated with metal implants. 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 strong results), two have been lost
to follow up, and four patients have continued to fair 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 microfracture)
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 exective 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.
CRW MD