Autologous Chondrocyte Implantation: Second-Look Arthroscopy

Abstract

Background:

A known complication following autologous chondrocyte implantation (ACI) for the repair of cartilage defects is graft hypertrophy. Although hypertrophic tissue can sometimes be asymptomatic, it may cause pain, catching, or effusion prompting a debridement operation—the most common cause for reoperation.

Indications:

Second-look arthroscopy is required for debridement of symptomatic hypertrophic or delaminated tissue.

Technique Description:

First, the graft is distinguished from the surrounding tissue. Visually, the graft has a lighter white color than the surrounding egg-shell-colored native cartilage. With a probe, it can be appreciated that the graft also has a softer texture than the firmer surrounding cartilage. Once the graft is identified, hypertrophy can be appreciated by the extent of raised margins from the surrounding cartilage. Delamination can also be seen by visualizing separated strands of graft on the surface or separation of the graft at the margins. A probe may then be used to gently assess the extent of the delamination. After diagnosing hypertrophy or delamination, a shaver is used to gently debride the tissue back so that it becomes flush with the surrounding tissue. Special care must be taken as to not over-debride the tissue, as this can subsequently lead to recurrent cartilage defect.

Results:

Patients are expected to have resolved pain, catching, and clicking sensations as well as resolved graft-associated effusion following this procedure.

Discussion/Conclusion:

Due to the incidence of symptomatic graft hypertrophy and delamination following ACI, second-look arthroscopy may be necessary to evaluate and possibly treat a cartilage defect following its repair.

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 is a technique video about autologous chondrocyte implantation: second-look arthroscopy.

Conflicts of interest are disclosed here.

The main case relates to a 36-year-old male teacher and soccer coach who sustained a right knee injury while playing volleyball a few years ago. Symptoms markedly worsened while running a race 6 weeks prior to presentation, and the patient experienced anterior and deep knee pain associated with loss of motion and catching sensations.

On physical examination, he ambulated with crutches bearing minimal weight on the right lower extremity. Right knee range of motion was 0° to 90°. Point tenderness localized primarily to the lateral femoral condyle with the knee flexed 90°. There is a small effusion.

Preoperative x-rays demonstrated very minimal joint space narrowing.

Preoperative magnetic resonance imaging (MRI) demonstrated 3 regions of cartilage injury. The first injury was about the medial femoral condyle with subtle findings on the MRI. The second defect was about the lateral femoral condyle. This was a more obvious full-thickness cartilage defect with crisp borders. The sagittal views also depict subtle findings with respect to the cartilage injury of the medial femoral condyle.

However, the third defect becomes apparent on these views. This defect involves the inferior aspect of the patella, and again, the full-thickness cartilage defect of the lateral femoral condyle is readily apparent. These MRI findings about the lateral femoral condyle, along with the symptoms of pain, loss of motion, and catching sensations, led to arthroscopy with chondroplasty and articular cartilage biopsy. The size of each articular cartilage defect was carefully measured.

During the autologous chondrocyte implantation, or autologous chondrocyte implantation (ACI), the medial femoral condyle defect was uncontained about the intercondylar notch. Suture anchors were used to secure the membrane in this region. Similarly, here are images of the lateral femoral condyle defect, preparation, template usage, and autologous chondrocyte implantation, and finally some similar images about the patellar defect, the largest defect in this knee.

The patient had an essentially satisfactory postoperative course; however, around 9 months postoperatively, he noted some pain. This pain localized primarily laterally was associated with some swelling and occasional catching sensations. The postoperative, or second-look MRI, revealed that the patella appeared to have excellent fill and integration in the region of prior ACI.

The medial femoral condyle defect appeared to have satisfactory fill in the region of ACI; however, some overfilling or hypertrophy was apparent here. The healing of the ACI about the lateral femoral condyle also demonstrates some hypertrophy, with more obvious change of contour here. And again, on the sagittal views, the patella appears to have excellent fill and integration in the region of prior ACI, with some possible prominence inferiorly. With respect to the lateral femoral condyle, the sagittal views confirm a subtle change of contour with prominent repair tissue. Arthroscopy following autologous chondrocyte implantation may be indicated in a patient with pain, mechanical symptoms, and or swelling. There may be point tenderness, palpable or audible crepitus, and or an infusion. On MRI, hypertrophic tissue and subchondral bony edema may be noting the region of prior ACI.

Overall, these findings of hypertrophy on the MRI, along with the recent pain and catching sensations, led to a second-look arthroscopy. The medial femoral condyle defect healed with some global hypertrophy. The superficial tissue was prominent and soft like a pillow. The integration with the surrounding native articular cartilage was excellent.

The surgical treatment principles involved removal of any grossly prominent tissue and any grossly nonfunctional tissue. The mechanical shaver, with the sharp, non-serrated edge, seems to work well for this task. After removing the unwanted soft hypertrophic tissue, the remaining ACI tissue was firm, fixed, and flush with the surrounding native articular cartilage. The lateral femoral condyle defect also demonstrated excellent fill and integration overall, and it also demonstrated global hypertrophy, but this hypertrophy had a different character. The central tissue was the most prominent and had already started peeling, like layers of an onion.

The treatment of this hypertrophy was similar, using the mechanical shaver to remove the grossly prominent tissue and grossly nonfunctional tissue. The patella defect also demonstrated excellent fill and integration with the surrounding native articular cartilage overall. There was some marginal hypertrophy noted about the inferomedial aspect. The motorized shaver was able to resect this tissue. I should note that throughout this case, multiple new shaver blades were opened. They seem to dull quickly performing this sort of work and become ineffective, and again, this work continues until the residual ACI tissue is firm, fixed, and flush, or even gently recessed. That concludes the main case in second-look arthroscopy.

However, I wish to present 3 additional videos. In case 2, the lateral femoral condyle defect healed with poor integration about the lateral aspect. The ACI tissue healed with good fill and integration otherwise. Specifically, ACI tissue around the majority of the defect was firm and stable. In contrast, the repaired tissue about the lateral margin was shredded, with an appearance like crab meat. You may have noticed some suture material within the adjacent meniscus. While the suture was placed several years prior to the ACI and the meniscus is well-healed, perhaps this challenged the healing tissue. Regardless, the treatment principles are the same—the removal of any grossly prominent tissue, the removal of any grossly nonfunctional tissue, using the mechanical shaver, and again, the residual tissue is firm, fixed, and flush.

In case 3, this defect healed with global hypertrophy, like a muffin rising and expanding over the edges of the foil. Unfortunately, the prominent tissue had partially delaminated about the anterior margin. This is analogous to a sofa seat cushion that is thicker than the surrounding seat cushions. Sweeping your fingers along the top of the sofa will grab that edge and try to flip that prominent cushion out.

In these cases, I removed the pieces that are already delaminated, as I am unaware of any cases of successful healing following fixation of the laminated ACI. Fortunately, the delaminated portion is usually a narrow portion about the margin. The majority of the ACI tissue remains intact.

In case 4, the femoral condyle defect demonstrated excellent fill and integration overall. A metal probe is useful in interrogating the margins. When considering a block of ice sliding on a block of ice, it would just take a small nail sticking out of one of the blocks of ice to interfere with fluid motion. In this case, most of the defect appeared smooth; however, at the posterior margin, there was some blistering of the repaired tissue. Some changes were noted about the adjacent articular cartilage of the tibia. The surfaces were smooth using the mechanical shaver and any grossly nonfunctional tissue was resected. Of note, rarely, there can be issues of healing about the biopsy site, in his case about the far lateral aspect of the trochlea. This was smoothed with a motorized shaver.

The postoperative rehabilitation can follow the routine knee arthroscopy protocol with 2 additional considerations. Between 3 and 9 weeks postoperatively, we encourage cycling for about 10 to 15 minutes each day, and please remember that if the patient is within the first 9 months following ACI, there may still be some activity limitations.

Return-to-sport criteria are outlined here. Please remember it must be biologically plausible that the ACI has healed enough to withstand the forces of sport.

In the short term, symptoms typically resolve within 3 months following the arthroscopy. In the long term, the outcomes are similar with and without arthroscopic procedures. ¹

Thank you for watching this technique video.