Treatment of Complex Multiple Lesions in the Knee With MACI (Autologous Cultured Chondrocytes on Porcine Collagen Membrane)

Abstract

Background:

Multiple chondral lesions in the knee are difficult to manage. A few treatment options are available. Considering the number of lesions, size, location, and total surface area, the autologous cultured chondrocytes on porcine collagen membrane (MACI) technique can effectively treat multiple defects simultaneously.

Indications:

The MACI procedure is indicated for multiple chondral lesions in the knee with large surface areas when other technologies are hard to implement or lack sufficient follow-up.

Technique Description:

The chondral defects are debrided to subchondral bone with vertical walls. Concomitant procedures are to be completed before MACI implantation. Each defect is treated as an isolated lesion. Irregular and uncontained lesions require a unique approach. A single membrane can treat multiple lesions; however, careful presurgery analysis is necessary to analyze the requirement of an additional membrane.

Results:

The MACI technique for multiple lesions in the knee has a good response rate and high satisfaction scores over mid- to long-term follow-up.

Discussion/Conclusions:

Multiple chondral lesions of the knee can effectively be treated with MACI, providing patients with additional improved quality of life, increasing level of function, and possibly delaying total knee arthroplasty procedures.

Patient Consent Disclosure Statement:

The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.

Graphical Abstract

This is a visual representation of the abstract.

Video Transcript

This will be a case presentation involving multiple articular cartilage lesions in the knee treated with the autologous cultured chondrocytes on porcine collagen membrane (MACI) technology. My disclosures are that I am a consultant for Vericel Corporation.

Background

Large multiple defects may have multiple treatment options. In this case, we chose to use MACI as our treatment. This will be a case study demonstrating the surgical approach, outcomes, data, postoperative management and rehabilitation, comments, and a final summary. It is important to consider many factors when treating multiple lesions. This includes the number of lesions, the size of lesions, the total surface area (TSA), location, and whether there is bony involvement. In comparing the use of MACI versus osteochondral allograft (OCA), MACI is a cell-based solution for surface lesions. Because of the flexibility of the membrane, you can treat convex, concave, and flat surfaces. It is much more challenging for OCA to match the topography of these multiple lesions.^3,11 And with larger lesions, there is a higher risk of nonincorporation of bone using the OCA graft. This will be a complex and salvage case and therefore requires a very thoughtful approach. ⁷ We need to consider the predisposing factors for this case, the sequence of approach for each lesion needs to be carefully planned out, and we need to map out the membrane so that we do not run out of membrane to treat these lesions.

This is a 38-year-old woman who always had a high level of activity and has had a progressive loss of function due to articular cartilage wear not related to a specific traumatic event. The TSA of her defects is approximately 17.5 cm². The patient's treatment goal, as she understands and accepts, is to try to restore her knee to a functional, pain-free state. In looking at her x-rays, we can see that there is good maintenance of the joint space in all aspects of the joint, as well as maintenance of good alignment in both the tibiofemoral and patellofemoral joint. The magnetic resonance imaging (MRI) sequence shows us on the medial femoral condyle (MFC) the full-thickness articular cartilage defect. In general, it is important to realize that the lesions may appear smaller on the MRI because it is just showing areas of complete cartilage loss, not indicating the quality of the cartilage surrounding the lesion, which often is also broken down and makes the lesion larger.^6,8-10 Arthroscopic evaluation in the knee joint confirmed the presence of these 4 lesions. You can see the MFC lesion, the lateral femoral condyle (LFC) lesion, and the kissing lesions or bipolar lesions on the patellofemoral joint involving both the patella and trochlea.

Technique Description

Once we have completed the arthrotomy, we can look and see the exact defect and get it exposed well. Here is the MFC lesion, and we want to make sure we have clear exposure of all the lesions involved, so both the MFC and the LFC. For the LFC, we chose to use a cutter that included most of the damaged cartilage and took minimal bad cartilage. Once we have delineated that, we will go ahead and start taking away the damaged cartilage using an open ring curette. We want to be careful not to go ahead and invade the subchondral bone plate, yet make nice healthy vertical walls of articular cartilage. Once the defect is delineated well, we will confirm that we have good margins that include good, healthy articular cartilage, and we want to make sure they have a very nice vertical component. Here, you see bleeding that sometimes will be created, especially if they have had a microfracture or other procedure like that in the past. Once we get the bleeding controlled, we will use pledgets soaked in epinephrine, which will be our first line of defense. We will then go ahead and use these in this position. We can also use thrombin soaked in surgical gel foam or, if there is little channel in the bone, fibrin glue. What we do not want to do is use a Bovie on the subchondral bone to try to create hemostasis.

We will then look at the MFC, where we have a more irregular-shaped defect. The important aspect here is we want to make sure that the cutter fits the defect and not making the defect fit the cutter. So here we are going to do this in a freehanded position so that we take away the minimal amount of healthy cartilage and just take away the damaged, irregular cartilage. We will do that sharply with a No. 15 blade, delineating that around its entire circumference. And then again, using the open ring curettes, we will take away the damaged cartilage, creating nice vertical walls of good, healthy cartilage along the edges and again taking care not to damage the subchondral bone plate. Once we have achieved that, we can then see how much bleeding there is and, in a similar fashion, go ahead and control that bleeding. We will then create a template using either the foil from a suture pack or a scalpel blade and, for consistency, keeping the colored side down, knowing that the colored side is always going to be cell side based. In true carpentry form, you always want to measure the template twice before you start cutting to make sure you have an adequate fit.

We will then move to the trochlea, where there is a much larger lesion, and we want to make sure we get all the damaged cartilage out of there, especially where it is thin toward the edge. We will go ahead and trim that cartilage away. Once we delineate the size of the lesion, we will go ahead and use our No. 15 blade, and again, because of the size and irregular nature of this, this is again going to be used in a freehanded fashion. Here you can see a very large defect going across the entire trochlea but good healthy vertical walls around it. The cartilage on the inferior margin might be a little bit thinner, but it is still good, and healthy cartilage is present. We will go to the patella, and we will delineate that defect, and you can see these areas of both grade 4 as well as some damaged grade 3 type of cartilage as well, and all of that needs to be removed. We were able to use an appropriate size cutter, and that will delineate it, and you can actually use the cutter as a border, so you do not sky off of that. The important thing here is getting all that damaged cartilage out, not invading the subchondral bone. Here, we are measuring it in multiple fashions, and then we will proceed to doing our tibial tubercle osteotomy. This osteotomy will just be an anteriorization without transferring it medially, and this is to unload that area of the bipolar lesion in the patella and trochlea. Once we elevate that appropriately, we will put bone graft in underneath, create 2 screw holes, and place 2 bicortical screws to fixate this in place. I prefer to do this before we go ahead and place the membranes on the defects so that we do not risk any damage. We will now proceed to create our membranes, and we will use our templates first as we go ahead and do these. You want to minimize the amount that you touch the membrane itself so it is just at the edge on an area that you will not be using. You will place a thin layer of fibrin glue, and you want to drip this in so it covers the entire area. We will then take the membrane with the cell side down and, that is, the rougher side, not the smooth side, and place it into position. Place a nice thin layer of fibrin glue around the edge and press that into contact to make sure it is in good place.

We will then move ahead to the lateral membrane using a cutter, hitting it only once or twice so that we cut through and make a nice, clean cut. We will then remove the remaining membrane back into solution to keep it for our further use, and again, in a similar fashion, we will place a thin layer of fibrin glue, place our membrane into the defect cell side down, and then seal the edges once again with the fibrin glue. Moving on to the trochlea, again, we use a freehanded template, and because of the large size and irregular shape of this, I selected 6.0 dyed Vicryl sutures, placed intermittently to keep it into position.

With the patella, we also created the membrane, and then we are going to sew in this uncontained area at the bottom, and we will do that using, again, the 6.0 dyed Vicryl sutures going from the membrane to the soft tissue, making sure to bury the knots off of the membrane, as this will contain it and keep it in place. We will then, once again, seal the edges with fibrin glue. In closing, we do a standard closure: subcutaneous tissue is closed, skin is closed, dressing is applied, and a postoperative hinged knee brace is applied as well.

Results

Our primary goals in the postoperative period are to protect the graft. We would like to do as much motion as possible, without overloading or damaging the graft, and gradually increase the mobility of the patient. ⁴ Postoperative pain control is very important to allow patients to feel comfortable moving their knee joint. We want to try to get as much extension as early as possible so we do not get posterior scarring. You can see in the video this patient walking, at 9 months, and is very comfortable with her gait. She is still working on building her strength and endurance but is able to do much more activity than she previously could. Her progression of therapy is outlined in this timeline here. She has recently been seen at 14 months, and you can see a video of her doing 90° squats with a weight and fairly pain-free, and she would consider her satisfaction score as very satisfied and results good to excellent.

Discussion

It is interesting to note in the literature that the outcomes for the treatment of multiple defects show no difference between the treatment of single defects using the MACI technique.^1,2,5 This is a second look at 3 years, a courtesy of Dr. Tom Minus in a patient with multiple lesions, and again, you can appreciate a good fill rate and integration. Some of the important considerations is that there will be a slower rate of maturation with multiple lesions, and this is based on lesion size as well as TSA. There certainly will be some restriction of activities long term, and this is to prolong the longevity of the graft. There is a higher risk of postoperative complications, mostly due to adhesions and often fibrosis, but this can be minimized by trying to minimize bleeding inflammation and emphasizing mobility of the knee joint. And there is no doubt that this is a bridging procedure. I often tell patients that this is not going to be their last knee operation, but for someone in their 30s, if we can get them into their 50s, there will be multiple options available for them at that time.

In summary, we see a good response and fill rate with multiple lesions. We were able to match the geometry of the multiple lesions utilizing a membrane. We can treat each defect as an isolated lesion, and we can overcome the complex topography because of the flexibility of the membrane. And that also allows us to do biomechanical realignment of the joint to minimize force overload. In uncontained lesions, you must be prepared to suture the membrane, or if there is a substantial size difference, you need to suture that to make sure it stays in place as well. If you are using a freehand preparation, you want to make sure the membrane matches the lesion size and shape and not get confused when flipping the membrane into position within the knee joint. Interestingly, the single MACI membrane is large enough that you can treat multiple lesions as compared to an OCA, where you may require multiple grafts from multiple compartments that are involved.

I would like to acknowledge the patient for her cooperation, Sue Rothberg for video production, Rusty Winkler as my surgical assistant, and the people at Vericel Medical Affairs. These are the references that were used in this presentation.