I Favor Allograft Replacement for Menisci Torn Beyond Repair

A Devil's Bargain for Athletes

Missing menisci find their way into the headlines every few weeks. Over the past year, Gaelic football player Kevin Dyas of Armagh, Northern Ireland[1]; soccer player Jérémy Mathieu of Barcelona, Spain[2]; and baseball player Michael Saunders of Toronto, Canada,[3] have all parted with portions of their menisci.

In past years, athletes could make such decisions blithely, because recovery is usually rapid and they can typically return to play with few symptoms.

Today a procedure leaving less than 70% of a meniscus intact looks increasingly like a devil's bargain. As I discussed in last month's column, in exchange for the quick recovery, the patient faces a great risk for eventual osteoarthritis. Pros must weigh the short-term benefits to their careers against the long-term risk for crippling pain in middle age.

"I decided to have the meniscus removed, for my national team and for my club," Mathieu said, according to Sport magazine.[2] "We'll see about [the effects] when I retire. When I'm 62, maybe I will be limping."

The Best Hope for Cartilage Protection?

Mathieu will be lucky if he's pain-free for that long. While I understand the motivation of a career in the spotlight, I recommend that athletes and other young patients whose menisci are torn beyond repair get allograft replacements if and when it is timely and possible.

We don't know yet from randomized controlled trials whether a meniscus transplant can prevent arthritis, but the procedure does appear to offer the best hope for cartilage protection that we have in these patients.

Various alternatives to an allograft have cropped up over the years, such as a collagen or polyurethane scaffold. These are in early stages of clinical study.[4,5]

Some surgeons have used meniscus analogs made out of a variety of hydrogels. They may be of particular use in patients with significant arthritis, but as far as I know, no one has published results from any clinical trials.[6]

On the other hand, allograft tissue has shown significant clinical efficacy in a large percentage of cases.

In one long-term study, orthopedic surgeon Peter Verdonk, MD, PhD, of Ghent University Hospital in Ghent, Belgium, and colleagues followed 38 patients for a mean of 12 years after providing them with allograft menisci. The patients had all been experiencing pain and disability after previous meniscectomy. The transplant didn't eliminate the symptoms but it did improve them, and the improvement lasted throughout the follow-up period.[7]

Only seven of these patients needed replacement arthroplasty. Imaging suggested that the transplanted menisci were providing some protection to the patients' articular cartilage.[7]

Who Is an Optimal Candidate?

The best candidates for this procedure are young people who have lost a large portion of their meniscus tissue that can't be repaired. For example, some tears are both vertical and horizontal; you can put in all the sutures you want, but the big problem is that only the outer third of the meniscus has a blood supply. If the meniscus tears very far into the "white-white" portion (which has no blood supply), or it's fragmented and fibrillated in multiple pieces, there's no way to put it together to heal and be durable.

Most of the time, the damage results from an injury, but sometimes discoid meniscus tears seem to happen spontaneously.

If there is already damage to the articular cartilage by the time the patient comes to me, I use orthobiologic adjuvants such as hyaluronic acid, platelet-rich plasma, and stem cells to minimize any further disease progression.

One of the challenges of the procedure is explaining its necessity to patients. Unlike Dr Verdonk's patients, many of mine are free of symptoms after their meniscus is removed. I talk about the outcomes studies and about our experience.

If I had my druthers, I would put in the transplant at the same time that I remove the torn meniscus. But typically I don't have that luxury; most patients I treat have already had their meniscus removed before they come to me, and there are already some degenerative changes to the articular cartilage.

Logistics and preparation may also be a challenge, as it takes time to procure the right allograft. It has to be sized. They're fairly available, but it's not like ordering a screw. For a very large or small size, you may have to wait a long time.

Then there is the insurance part of the case; I have to be able to show that there is a meniscus deficiency before I can get the payers to accept it.

An x-ray tells me whether joint spaces are maintained and that the articular cartilage is not damaged. Grade 3 (fissuring) and 4 (exposed bone) in the Outerbridge Classification are contraindications. You don't want to put a new meniscus in a knee where bone is already rubbing on bone because it will just wear down the meniscus. The whole reason to put in a meniscus is to preserve the cartilage.

The x-ray will also show any boney abnormalities. It will show whether the joint space is sufficient to receive the transplant, as well as whether there is any significant malalignment that could damage the meniscus.

Next comes MRI. The MRI shows exactly how much of the meniscus remains and gives me a further understanding of the status of the joint. It can reveal lesions within the bone and will tell me whether I need to reconstruct any ligaments or correct a malalignment with an osteotomy.

Finally, I can send the MRI image to the organization that is providing the donor allograft to size the meniscus. You can't take the meniscus of a 5'1" child and put it in a 6'4" man; the size has to be pretty exact—within millimeters.

Three Surgical Approaches

When it comes down to the procedure itself, surgeons these days are mostly using one of three techniques.

One technique utilizes all soft tissue. You make holes in the tibia and suture the meniscus through these holes. In the laboratory, however, researchers have shown that meniscus attachments using only soft tissue don't restore the normal biomechanical stress distribution that the normal meniscus should.[8]

Another approach is the trough technique. Rather than using two separate pieces of bone that come with the meniscus, you use only one. A box cutter is used to make a trough in the tibia, and then the piece of bone attached to the meniscus slides into that trough. My critique of the trough technique is that it removes a lot of bone and cartilage that don't need to be removed.

The third approach is the anatomic bone block technique, a surgical procedure in which a bone graft is placed adjacent to a joint to limit motion of the joint mechanically or to improve the stability of the joint. This approach preserves the attachments to bone blocks at the posterior and anterior horns of the meniscus. Drill holes in the tibia the size of these blocks, and then insert the blocks into these holes. Special sutures that come through the meniscus and through the bone secure the two together. You can either tie the ends of the sutures together or use a button to tie them outside the bone on the tibia. I prefer this approach because it restores the normal interrelationships between the meniscus and its attachments, and I've had good results with it.

The procedure takes about 1-1.5 hours to do, and the patient goes home that day. Patients are kept in a brace for 3 weeks and on crutches for another 3 weeks. They then go through gradual rehabilitation, including stationary biking and swimming. We limit their activities for about 6 months as the meniscus tissue begins to adapt to its new environment, regenerating itself and its connections.

In the long term, we may want to add orthobiologic adjuvants, because our major concern is to keep the joint healthy and prevent osteoarthritis.

References

1.Kevin Dyas and Andrew Munin to miss Armagh's summer campaign. RTE Sport/GAA. May 5, 2015. http://www.rte.ie/sport/gaa/2016/0505/786303-armagh/ Accessed May 16, 2016.

2.Mathieu explains why he decided to have his meniscus removed. Sport. April 29, 2016. http://www.sport-english.com/en/news/barca/mathieu-explains-why-decided-have-his-meniscus-removed-5097599 Accessed May 16, 2016.

3.Chisholm G. Saunders moving forward after knee surgery. MLB.com. February 28, 2015. http://m.mlb.com/news/article/110745448/toronto-blue-jays-outfielder-michael-saunders-moving-forward-after-knee-surgery Accessed May 16, 2016.

4.Zaffagnini S, Grassi A, Marcheggiani Muccioli GM, et al. Two-year clinical results of lateral collagen meniscus implant: a multicenter study. Arthroscopy. 2015;31:1269-1278. Abstract

5.Bouyarmane H, Beaufils P, Pujol N, et al. Polyurethane scaffold in lateral meniscus segmental defects: clinical outcomes at 24 months follow-up. Orthop Traumatol Surg Res. 2014;100:153-157.

6.Hayes JC, Curley C, Tierney P, Kennedy JE. Biomechanical analysis of a salt-modified polyvinyl alcohol hydrogel for knee meniscus applications, including comparison of human donor samples. J Mech Behav Biomed Mater. 2016;56:156-164. Abstract

7.Verdonk PC, Verstraete KL, Almqvist KF, et al. Meniscal allograft transplantation: long-term clinical results with radiological and magnetic resonance imaging correlations. Knee Surg Sports Traumatol Arthrosc. 2006;14:694-706. Abstract

8.Alhalki MM, Howell SM, Hull ML. How three methods for fixing a medial meniscal autograft affect tibial contact mechanics. Am J Sports Med. 1999;27:320-328. Abstract

Medscape Orthopedics © 2016 WebMD, LLC

Any views expressed above are the author's own and do not necessarily reflect the views of WebMD or Medscape.

Cite this article: I Favor Allograft Replacement for Menisci Torn Beyond Repair. Medscape. May 20, 2016.

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