August 7, 2012

http://www.stoneclinic.com


Meniscus Transplant (Meniscus Replacement) Overview
By replacing all or a portion of the meniscus with donor cartilage, the patient can regain the natural “shock absorber” in the knee and experience many additional years of activity, even in the presence of arthritis. Being "bone-on-bone" does not always mean the joint needs to be artificially replaced; often the "bone-on-bone" is isolated to a portion of the knee joint and this can be repaired using a meniscus transplant alone or in combination with any of our Biologic Joint Replacement ProgramSM procedures.

Meniscus Transplant Medical Conference Presentation

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To facilitate meniscal cartilage replacement, specific instruments and techniques have been developed to ensure accurate and reproducible placement of the meniscal implants.

Do meniscus transplants as a component of the Biologic Joint Replacement ProgramSMwork?  See the results by clicking here or continue reading below for additional information on the meniscus transplant surgical technique and a patient experience.  More patient experience videos on meniscus transplant and the Biologic Joint Replacement ProgramSM can be viewed here.



Meniscus Transplant Surgery
For meniscal cartilage replacement to succeed, the following goals must be accomplished:
- The torn fragmented pieces of native meniscal cartilage must be removed.
- The attachment sites for the meniscal horns must be anatomically placed.
- The periphery of the meniscal implant must be attached securely enough to permit axial and rotational loads.
- The surrounding capsule and ligaments of the knee joint must be neither excessively violated nor constrained by the fixation technique.

To achieve these goals, the following steps are recommended. Initially, complete diagnostic arthroscopy of the knee joint is accomplished in the routine fashion. If anterior cruciate ligament surgery is to be performed simultaneously, the femoral and tibial tunnels for the cruciate reconstruction should be drilled first. 

Meniscus Transplant Surgical Procedure: Medial Meniscus

 
Meniscus Transplant Surgical Procedure: Lateral Meniscus


 
Meniscus Transplant Surgical Procedure: Detail
 
In order to succeed, a replacement must duplicate the mechanical function of the original meniscal cartilage. The technique of replacement described in this article permits minimal disruption of the joint tissues, accurate placement of the meniscal horns, and secure fixation of the meniscal synovial junction.
 

Fig. 1
The torn portion of the meniscal cartilage is evaluated. If meniscal repair cannot be accomplished due to severity of the tear or poor quality of the tissue, preparation of the meniscal rim is undertaken by removing the torn portions of the cartilaginous tissue (Fig. 1). In the setting of allograft replacement, nearly all of the remaining meniscus is removed. Additionally, for allograft replacement, resection of the meniscal horns and preparation of bony tunnels to accept bone plugs may be required. In the setting of scaffold replacement, only the damaged portions are removed, preserving the peripheral rim and horns for attachment of the scaffold. If absolutely no meniscal rim is present, meniscal scaffolding should not be performed. If the joint is excessively tight, a joint distractor may be applied or the medial collateral ligament may be partially released. 

Fig. 2
For medial or lateral meniscal replacement, place the arthroscope in the mid-lateral or anterior lateral portal and the tibial guide through the anterior medial portal. The tip of the guide is brought first to the posterior horn of the meniscus. It should be noted that the posteromedial horn inserts on the posterior slope of the tibial eminence. A drill pin is then brought from the anterior medial side of the tibial tuberosity to the posterior horn insertion (Fig. 2).

Fig. 3
The pin placement can be confirmed by passing the arthroscope through the intercondylar notch and viewing the exit site of the pin. Extreme care must be undertaken to avoid penetration through the posterior capsule of the knee, endangering the neurovascular bundle. When the pin position is confirmed, the pin is then over-drilled with a 4.5-mm cannulated drill bit with the option of a drill stop to prevent posterior capsular penetration (Fig. 3). The bit is left in place and used as a tunnel to pass a suture passer with a #2 Ethibond (Johnson & Johnson) suture. The suture is passed up the bore of the drill bit, the drill bit removed, and the suture left in place. 

Fig. 4
Attention is now turned to the anterior drill hole. For the medial meniscus, it must be noted that the anterior medial meniscus insertion varies considerably. Most often it can be found anterior to the medial tibial eminence. The anterior horn of the lateral meniscus inserts just posterior to the ACL. Identify this insertion and place the tip of the drill guide so that a relatively vertical hole will be made (Fig. 4). Place the drill pin, then overdrill with the cannulated drill bit and place the suture passer. Alternatively, the anterior horn of the medial meniscus may be affixed with a suture anchor directly to the bone. Before grasping the suture from the anterior and posterior drill holes, widen the anterior portal to approximately 2 cm. The suture grasper should be passed through the widened portal and both the anterior and the posterior sutures brought out simultaneously. This technique prevents the sutures becoming entangled in two different planes of the fat pad and capsular tissue. The importance of this step cannot be overstated; occasionally the posterior suture will pass through one tissue plane and the anterior through another plane causing the implant to become stuck in the soft tissues.

Fig. 5
The implant is now brought onto the field. Two horizontal mattress sutures of #2-0 Ethibond are placed through each horn of the implant with the free ends exiting the inferior surface (Fig. 5).
 

Fig. 6
The two posterior sutures are then drawn through the knee and out the posterior tibial tunnel (Fig. 6). If viewing from a mid-lateral portal, the anterolateral portal can be used for probe insertion to push the implant medially into place through a 1-inch incision. No insertion cannula is required. The anterior sutures are then similarly passed, and the horn sutures are tied over the anterior tibial bony bridge.

Fig 7.
Next, zone specific meniscal repair cannulae are brought into place. For medial insertions, a series of small puncture incisions are used to retrieve the sutures. Through these multiple small incisions, the suture needles can be captured and the knots placed directly over the capsule (Fig. 7). Although nonabsorbable suture is used for the meniscal horns for added strength, absorbable suture [2-0 polydioxone (PDS)] is recommended for the body of the scaffold. The smooth monofilament is less abrasive and resorbs as the scaffold is metabolized.
When using the meniscal repair needles, the posterior cannulae should be used first with the sutures placed vertically and evenly spaced. Progress from posterior to anterior so that a buckle is not produced within the implant. Tie each knot as it is placed to avoid the chance of suture tangling. Space the knots approximately 4 mm apart. Cycle the knee through several complete ranges of motion to ensure the implant moves smoothly without impingement.

When performing a lateral meniscal replacement, we now preserve a bone bridge between the horns of the meniscus and create a trough to secure it on the tibial plateau. The remainder of the insertion technique remains the same, except that great care should be taken to protect the neurovascular bundle when suturing the posterior horn. We prefer suture knot tying through small puncture holes rather than open posterior lateral or medial incisions.

Routine skin closure and dressings are applied. Thirty milliliters of 0.5% Marcaine (Astra) with epinephrine mixed with 30 cc of lidocaine are always instilled for immediate post-operative pain relief.

Meniscus Transplant Rehabilitation

Meniscus Transplant

Who needs a meniscus transplant?
Meniscus transplantation, or placing cartilage from a cadaver donor into a patient, has become a possible treatment for patients with a specific pattern of knee pain. The ideal patient is someone who had their meniscus removed, and subsequently begins to develop knee pain. The patient is too young and too active to consider a joint replacement. Yet all the other "usual" treatments (anti-inflammatory medications, physical therapy, Synvisc, cortisone, joint supplements, etc...) just aren't doing the trick. The questions is, what is a reasonable treatment.


In the last decade, meniscus transplantation has become a reasonable treatment option to be considered for some patients with specific types of knee pain. The problem is, the number of patients for whom a meniscus transplant is a reasonable option is quite small. That said, if you think you may fit the criteria for considering a meniscus transplant, read on....
What is the meniscus?
The meniscus is a complex structure that provides both cushioning and stability to the knee.
  • For information about the meniscus, and how it works, click here...
Without the meniscus present, patients are much more likely to develop accelerated degenerative changes to the knee joint. As this happens, the remaining cartilage that covers the ends of the bone, called the articular cartilage, is worn away, and bone is exposed.
For this reason, orthopedic surgeons attempt to preserve the meniscus when surgically treating a torn meniscus. During surgery, only the damaged portion of the meniscus is removed, or your surgeon will perform a meniscal repair if possible. Unfortunately, despite advances in arthroscopy, not all meniscus tears are amenable to repair. In some cases, in order to best treat the damaged meniscus, the entire meniscus must be removed.
What happens when the meniscus is removed?
When the meniscus is removed, the patient is left without much of the joint cushion. Initially, this tends not to be a problem. But over time, patients often develop pain where the meniscus was removed, and they can go on to develop accelerated arthritis in that part of the knee joint.
The hope of a meniscus transplant is that by restoring the normal joint support and cushioning of the meniscus, the pain will be alleviated and the degenerative changes will slow. It is important to understand, this is the goal of meniscus surgery, and while early studies show cause for optimism, it is not known that a meniscus transplant has any effect on protecting the joint from further degeneration!
Who is a good candidate for a meniscus transplant?
  • A young to middle-age patient (20-50 years old)
  • Underwent prior meniscectomy (removal of meniscus)
  • Normal or limited damage to the articular cartilage (bone lining) of the joint
  • Symptoms consistent with the absence of a meniscus
Unfortunately, finding a patient who fits these criteria is a difficult task. Many patients have undergone a prior meniscectomy (meniscus removal surgery), and many of these patients have persistent problems related to the removal of the meniscus. However, most people who become symptomatic because of the absence of a meniscus, already have developed damage to the cartilage that remains in the knee. Patients who have this accelerated degenerative change to their knee joint are not good candidates for meniscus transplant surgery.

As described previously, patients must fit specific criteria in order to be considered a good candidate for meniscus transplant surgery.
You are not a good candidate for a meniscus transplant if:
    • You still have a significant portion of the meniscus remaining (this procedure is only for patients who had the bulk of the meniscus removed)
    • You have degenerative changes within the joint (early arthritis)
    • You have instability or malalignment of the knee joint
    • You are unwilling to perform the lengthy rehabilitation from meniscus transplant surgery
    • You have unrealistic expectations
    Allow me to further explain this last point. Some patients are looking for solutions that surgeons cannot necessarily offer. The goal of a meniscus transplant surgery is to reduce pain associated with normal activities. The goal is not to give the patient a "normal" knee, but rather to make it better. It is possible that patients may not be able to resume competitive athletics despite a successful meniscus transplant. Patients who expect more than reduction of pain may want to consider other options as they may find disappointment with their results.
    What is the rehabilitation from meniscus transplant surgery?
    This varies depending on the exact procedure your doctor will perform. Most surgeons have patients protect the knee with crutches for four to six weeks. Patients will not be able to squat, run, or perform athletic activities for at least several months. Most patients who have a successful outcome return to their usual activities by about six months from surgery.
    What are the risks of meniscus transplant surgery?
    The risks of every surgery must be carefully considered, but there are some unique risks to meniscal transplant that patients should be aware of.
    • Long-term results are lacking
      Long-term results simply are not available because meniscus transplantation is a relatively new procedure. There are some mid-term (3-6 year) studies which show encouraging results, but no one knows for sure how well these knee will be working in 10 or 20 years.
    • More surgery may be coming
      Studies have shown a significant number of these patients do require further surgery, about 30%. If you are looking for one-stop shopping, a procedure that you can confidently call your last, a meniscus transplant is not for you.
    • The transplant can fail
      Not all transplants have healed into position, and some need to be removed because they end up causing more problems than they solved. Even if you undergo proper rehabilitation and therapy, there is a significant chance that your new meniscus will not heal into your knee.
    • Disease transmission
      There is a very small, but a very real risk of disease transmission when using another persons tissue in your body. These tissues are preserved and cleaned to destroy bacteria and viruses, but there are no guarantees. There is a theoretical risk of HIV, hepatitis, bacterial, or other infectious disease transmission with these grafts. Again, the risk is very small, but not zero.