Combination of Cartiheal and Osteochondral Allograft for the Treatment of Multifocal Cartilage Defects

Abstract

Background:

Multifocal cartilage defects about the knee have become increasingly prevalent. When left untreated, these injuries may progress to diffuse knee osteoarthritis. Operative management for patients with multifocal chondral defects typically includes partial or total knee arthroplasty. The senior authors (A.H.G. and S.M.S.) suggest the simultaneous use of osteochondral allograft (OCA) transplantation for patellar chondral defects and the Cartiheal Agili-C implant for trochlear chondral pathology as a viable option for patients with bipolar patellofemoral pathology.

Indications:

Patients were indicated for the combined procedure presented in the clinic with symptomatic and functional difficulties with activities of daily living and sports. Magnetic resonance imaging evaluation demonstrated multiple chondral lesions. Patients failed nonoperative treatment measures, including a minimum of 3 months of formal physical therapy and injections.

Technique:

A diagnostic arthroscopy was performed. An arthrotomy was performed, and, using the standard OCA technique, the patella was everted, and the recipient site was sequentially reamed. The OCA was prepared on the back table with a coring reamer using irrigation. A small K-wire was used to microperforate the bone. The allograft was irrigated with pulse lavage and CarboJet, soaked in bone marrow aspirate from the distal femur, and placed in the patellar defect with digital pressure. Attention was turned to the trochlea. Using the Cartiheal Agili-C technique, a threaded guide pin was drilled into the lesion, then drilled, and a hand reamer was used to achieve the appropriate depth. A shaper was used, and the edge was beveled, and the Cartiheal Agili-C implant was placed. This was repeated as necessary.

Results:

The literature suggests that OCA transplantation is an effective means for treating isolated articular cartilage defects in the knee. Cartiheal Agili-C implant is a novel and effective treatment for focal chondral defects, an alternative to OCA when graft availability is limited, or the defect is narrow or small. The combined use of OCA and Cartiheal Agili-C implants can address complex defect pathology and improve patient symptoms and function.

Discussion/Conclusion:

Full-thickness, multifocal chondral defects about the knee are difficult to treat. The combined use of Cartiheal Agili-C implant and OCA transplantation poses an innovative treatment option.

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

Background

This surgical technique video describes the combination of Cartiheal and osteochondral allograft (OCA) for the treatment of multifocal cartilage defects. First of all, you have to look at why there is a cartilage defect or a chondral injury in the first place in the patellofemoral joint. It can be from trauma, fracture, direct impaction, an anterior cruciate ligament (ACL) tear, or a patellar dislocation. These patients often require the medial patellofemoral ligament (MPFL) or, if there is anterior translation, the ACL at the same time. It could be due to an osteochondritis dissecans lesion, but these are rarely bipolar and are also less common on the trochlea and the patella. Most often, we see patellofemoral cartilage lesions due to malalignment, but in this case, you can see on magnetic resonance imaging (MRI) that the surgery was poorly performed; they mispositioned the MPFL tunnels and violated the articular cartilage on the lateral facet of the patella.^10,14

Treatment of early patellofemoral compartment osteoarthritis is complex and necessitates a multifaceted approach to drive positive clinical outcomes. Published literature supports that cartilage restoration procedures are highly effective in preserving the native knee joint, improving patient-reported symptoms, and delaying or preventing more invasive partial or total knee arthroplasty. A systematic review evaluating cartilage restoration as an alternative to arthroplasty for bipolar patellofemoral chondral defects found that 80% of patients reported favorable outcomes. ⁴

OCA transplantation is an established cartilage procedure for patients with full-thickness cartilage lesions, but implanting it in the trochlea can be challenging because of its complex shape.

A study by Tchangou et al ¹³ examined the outcomes of patellar OCA transplantation. The study showed improvements in patient-reported outcomes and an 11% conversion rate to total knee arthroplasty at a 2-year follow-up after patellar OCA transplantation.^8,13 Meric et al ⁹ reported on outcomes of OCA to treat bipolar osteochondral lesions. While the study showed improvements in International Knee Documentation Committee (IKDC) and Knee injury and Osteoarthritis Outcome Score (KOOS) scores from baseline to the latest follow-up, nearly 46% of knees were considered failures. ⁹ In a follow-up study, out of 81 knees that underwent bipolar OCA, graft failure still occurred in 34% of knees at a mean of 4.8 years postoperatively, despite improvements in IKDC, KOOS, and KOOS sub scores. ¹ While OCA transplantation remains a viable treatment option, novel methods to treat bipolar lesions could help improve survival and patient reported outcomes.

Cartiheal Agili-C is a new off-the-shelf treatment option for osteochondral cartilage lesions of the knee. ⁶ The implant is a biologic aragonite-based scaffold derived from coral exoskeleton and promotes cartilage regeneration. It offers a less expensive and more available option for patients who are not indicated for arthroplasty but have symptomatic cartilage lesions, particularly those with narrow or long cartilage defects. The coral scaffold supports the regeneration of cartilage and subchondral bone at the defect and gradually degrades as new tissue grows. Matrix-induced autologous chondrocyte implantation is another option, but requires 2-stage surgeries and is expensive.^5,10,11

Indications

The indications for bipolar patellofemoral Cartiheal and OCA surgery are rare. Small lesions and minimally symptomatic lesions can often be treated with injections such as hyaluronic acid or platelet-rich plasma, as overall, cartilage defects are very common, especially on the patella. A large study on knee arthroscopies demonstrated a high incidence of asymptomatic patellar cartilage lesions. Trochlear lesions are less frequently encountered, in only 6% to 16% of arthroscopic cases. ¹² Importantly, not every structural defect causes pain; you have to localize the pain in the patient's knee and see if this is what is actually bringing them to your office. Not every defect needs treatment, especially inferior medial patellar defects or small defects, and we would consider these incidental findings. ³ Contraindications for this procedure include inflammatory arthritis and active infection.

The patient I am going to describe here is a 46-year-old woman with a body mass index of 22.3 kg/m² presenting with left knee pain. On examination, the alignment was neutral; however, she was unable to perform a single-leg squat. There was a trace effusion in the knee, and palpation was positive for medial facet tenderness. Range of motion was essentially full at 0° to 130°. She reported mild intermittent knee pain for many years, which was worsening, and she had tried physical therapy and corticosteroid injections.

Initial workup included anteroposterior, lateral, and Merchant views of her left knee. Here you can see mild patella alta, but a well-centered patella in the trochlea on the merchant view. On this axial proton density series, you can see this central trochlear defect with a small cyst. On the sagittal view, the patellar defect you see is patella alta, and the lesion is proximal. We typically take into consideration the tibial tubercle–trochlear groove (TT-TG), but the patient did not have significant lateralization or coronal plane malalignment. The patient also did not have significant sagittal plane malalignment. We do not have a strict TT-TG cutoff, but generally, this procedure is indicated in patients with normal patellar tracking. Therefore, on assessment, this patient was noted to have bipolar patellofemoral compartment chondral defects. The plan was arthroscopic evaluation followed by OCA in the patella and Cartiheal in the trochlea.

Arthroscopic images from the time of surgery reveal a pristine medial compartment, intact ACL, pristine lateral compartment, and no evidence of meniscal pathology. Looking at the trochlea, you see a full-thickness central trochlear defect, and evaluation of the patella reveals a full-thickness defect. The open image after the arthrotomy reveals a fairly large full-thickness defect extending over the median ridge to the lateral facet in the patella.

Technique Description

Beginning with the patellar OCA portion of this case, you can see this full-thickness lesion on the median ridge extending to the lateral facet of the patella. Using a medial or lateral peripatellar arthrotomy (in this case, medial), I first used towel clamps to evert the patella. I try to make a very small incision; sometimes it does have to be extended into the quad to fully evert the patella. I size the chondral lesion and typically start by reaming the patella with a low-profile, 11-mm reamer, even if I anticipate a 20-mm graft. The bone is quite hard, and I think it is easier to set your depth with a sharp single-use instrument. I then ream up: 12, 14, and 16 mm. When I get close to my desired size of implant, I use the cartilage cutter in the set and irrigate more carefully as I am getting close to the actual articular cartilage rim with the native cartilage. The depth is typically around 6 to 7 mm. In some patellar lesions, it is slightly deeper to allow bone on all sides of the graft. I then return to the back table and orient my reaming guide to the patellar allograft. I typically use 2 pins. You can then place the patella in the clamp or hold it with your hand. I then ream through using the coldest irrigation I can find, and as much as possible. I take this plug and then put it in the clamp after measuring all 4 sides—12, 3, 6, and 9 o’clock—to match the defect's depth. The saw is then used to cut the allograft on the backside, and then a small K-Wire (2.0) is used to microperforate the bone on the backside of the graft. We then use pulse lavage to thoroughly clean the graft, followed by CarboJet, and soak it in locally obtained bone marrow aspirate from the distal femur. It is important to place the graft using digital pressure. I do not use the impactor. The force experienced on the cartilage by using an impactor can kill cartilage cells. I have a dental pick ready in case I need to tweak the height of the graft. Depending on how deep the graft is, I occasionally ream just a little deeper or cut my graft on the back table to fine-tune the fit into the defect. I then turn my attention to the trochlea. It is often helpful to use a small bump to achieve about 20° of knee flexion. I often use a Z-retractor, a medial collateral ligament retractor, and a Paulson to get adequate visualization. Beginning with the perpendicular aligner, I put a marking pen at the end of it, especially if I plan to use multiple plugs. It is important not to converge these plugs, and you want to leave approximately 5 mm between the plugs. I then drill a threaded guide pin into the lesion. A laser line on this guide pin ensures it is drilled to the appropriate depth. There is then a drill with a depth stop. This is followed by a hand reamer, which is used to get to the appropriate depth. If there is a smaller arthrotomy and it is difficult to see, I will use my camera in the scope to ensure I have buried the laser lines. You then follow this with an instrument called a shaper. It is designed to create the Morse taper aspect of the defect, and you need to clear the bone off of this shaper several times. You should also be irrigating during this step to remove bone debris from the defect. The next step is the cartilage cutter. The cartilage cutter essentially works like a vegetable peeler, peeling away cartilage on the edges of the defect and beveling it. They have shown that increasing the surface area by beveling the edge is actually advantageous for cartilage growth. In some cases where access is a little more difficult, I have just taken a 15-blade to smooth out the edges using a small rongeur to remove any small flaps because nothing must be dragged into the defect: No cartilage, no fat, no skin cells. Therefore, at this point, I change my gloves and remove the implant from the packaging. The implant needs to be placed with the microperforated aspect facing outward. This implant has a slight Morse taper. You can place this implant with finger pressure, then use the plastic blue pusher to fully click it into place. This does not require significant force. You never use a mallet or any type of impactor. Once implanted, the implant should be flush with the native bone, approximately 2 to 3 mm below the cartilage surface. ⁶

Results

For postoperative care, I typically allow these patients to weightbear as tolerated, especially with patellofemoral lesions. I do place them in a brace locked in extension, but allow flexion from day one. For very large lesions, I occasionally use a continuous passive motion (CPM). I recommend an MRI at 6 months in all my cartilage cases. You can look at integration; you can assess for bone edema. In this series, you can see T2 mapping and clearly see where the Cartiheal graft has been placed, as well as the patellar OCA. There appears to be good cartilage fill. Postoperatively, I typically follow the patellar OCA postoperative guidelines. Return-to-sport progression is determined based on interval MRI findings and clinical assessment. If a 6-month MRI shows progressive filling of the cartilage lesion and resolution of bone edema, the patient can resume activities without limitation. If not, the MRI is repeated in 3 months.

Pearls include an immediate range of motion and compressive ice therapy to aid in recovery. Trochlear cartilage is often thicker; thus, it is important to confirm that the laser line is buried. Pitfalls for patients receiving multiple Cartiheal plugs include ensuring that the plugs are placed parallel to avoid convergence. It is also important to maintain 5 mm spacing between the plugs. Additionally, do not impact either OCA or Cartiheal plugs; instead, use finger pressure.

Discussion/Conclusion

The combination of Cartiheal and OCA is an exciting new joint-preserving option for patients who are not indicated for, or are looking to delay, partial or total arthroplasty. ² Many of these patients have long, narrow lesions in their trochlea, or small trochlear lesions with bone edema that you do not want to ignore. A 4-year randomized control trial comparing the Cartiheal Agili-C implant with debridement/microfracture for trochlear and condylar chondral and osteochondral defects showed that the scaffold group achieved superior clinical outcomes versus the surgical standard of care (SSoC), with significantly greater improvements in IKDC, KOOS, and KOOS subscales from baseline to 24 months and stable scores through 48 months. Also, 24-month radiographic results demonstrated the implant's superiority compared with SSoC in both men and women. In trochlear defects, 62.5% of patients in the scaffold group achieved at least 75% defect fill compared with 18.2% of controls.^2,3,7 At this point, we have now done approximately 90 Cartiheal cases; of these, 10 involved OCA and Cartiheal. As our typical protocol involves an MRI at 6 months, we have seen good short-term outcomes. Long-term outcomes are pending, and we will be following these patients closely.