Emerging Advances in Ankle Cartilage Repair

Written by Bob Baravarian, DPM and Rotem Ben-Ad, DPM

Damage to the cartilage in any joint of the body can have detrimental effects on the function and performance of that joint. This is particularly true for the cartilage of the ankle joint, specifically at the talar dome. Due to the body’s inability to repair cartilage to its original form, treating patients with osteochondral lesions has proven to be a challenge to even the most competent foot and ankle practitioner.

In many instances, conservative treatment with immobilization and non-weightbearing is adequate enough treatment to relieve symptoms. This is especially the case for stage I and II lesions.1 However, if conservative treatments fail for these lesions or if the lesion is significantly larger and more consistent as is the case with stage III or IV lesions, one must consider more aggressive options.

Arthroscopy with debridement and microfracture has generally been the predominant first-line surgical treatment for talar dome lesions. However, recurrence of symptoms following microfracture is not uncommon, especially with larger, deeper lesions, or those exhibiting subchondral damage.

Fortunately, there has been a lot of progress in the field of cartilage repair in recent years and this has led to improvements in the treatment of osteochondral lesions of the talus. The collective goal of all of these methods is to promote more hyaline-like cartilage as opposed to the fibrocartilage that is present following microfracture treatment.2 Accordingly, let us take a closer look at these emerging options.

What You Should Know About Autologous Cartilage Implantation

 
If treatment with microfracture has previously failed, autologous cartilage implantation may be a viable next step. Surgeons may also consider primary autologous cartilage implantation if the diameter of the lesion is greater than 2 cm or if extensive subchondral cysts are present like one might see with stage IV defects.3

Autologous cartilage implantation is a two-step procedure involving the harvesting of cartilage from a non-weightbearing surface of a joint, such as the supralateral femoral ridge of the knee.2 Other options include the non-weightbearing anterior surface of the talus.3 One would subsequently send the graft to the lab where chondrocyte isolation and proliferation takes about four to six weeks.

Surgeons would then perform a second procedure for transplantation. Generally, an open procedure is necessary for adequate exposure. This may or may not include a malleolar osteotomy depending on the size and location of the lesion. One would then implant the chondrocyte graft onto the defect after proper debridement. A periosteal flap is required in order to secure the graft and this may prove to be a tedious suturing process. However, a newer version of the procedure known as matrix-based chondrocyte implantation obviates this by fixing the chondrocytes in a collagen matrix. One can secure the graft with fibrin glue and no periosteal flap is required.

Regardless of this improvement, autologous cartilage implantation has fallen out of favor in the past few years due to the need for a staged, open procedure. Autologous cartilage implantation has predominantly been replaced by use of the DeNovo® NT Natural Tissue Graft (Zimmer), which we will discuss later in this article.


A Closer Look At The Osteochondral Autologous Transplantation/ Mosaicplasty

Indications for performing an osteochondral autologous transplantation surgery (OATS) or mosaicplasty procedure include a lesion that not only has a large cartilaginous component but a significant osseous component as well.4 This option can also be a last resort for lesions that have been recalcitrant to previous surgical treatment.

With this technique, the surgeon would graft an osteochondral plug from a non-weightbearing surface, usually from the knee, and transplant it into the damaged area of the talus. Alternatively, one can take the graft as multiple plugs, creating the mosaicplasty effect. Depending on the location of the lesion, a malleolar osteotomy may or may not be required.

In their retrospective study, Scranton and colleagues had good to excellent results of 90 percent at a mean follow-up of 36 months with the OATS procedure.5 It is important to note that 26 out of 50 patients required a malleolar osteotomy for adequate exposure.

The one major advantage of this procedure over autologous cartilage implantation is that the OATS procedure only requires one surgery to complete. Additionally, the surgeon is better able to restore the contour of the defective talus using the OATS procedure.

Sharpe and coworkers describe a hybrid technique in which they combined autologous cartilage implantation with OATS.6 The procedure entailed injecting autologous cultured chondrocytes under the periosteal patch of the previously inserted osteochondral cores. At the three-year follow-up, 10 of the 13 patients continued to relate favorable improvement in their symptoms. It is interesting to note that at a one-year arthroscopic evaluation, the osteochondral grafts were well integrated with the adjacent cartilage.


How An Innovative Natural Tissue Graft Can Help Reproduce Hyaline Cartilage

The development of methods to reproduce hyaline cartilage following cartilage damage has recently picked up momentum. The use of the aforementioned DeNovo NT Natural Tissue Graft has become a popular technique of doing this. This graft is made up of human juvenile hyaline cartilage. Research has shown these immature juvenile chondrocytes have a much larger capacity for self-repair in comparison to that of adult cartilage.7

There are a few other major advantages of this modality in contrast to either the OATS or autologous cartilage implantation. First, the DeNovo graft requires only one surgery, which surgeons can perform arthroscopically. In addition, no periosteal flap is required to secure the graft as surgeons can apply a fibrin adhesive instead.Lastly, no donor site morbidity is associated with the procedure since the surgery uses an allograft instead of an autograft. Although one can use the DeNovo graft for lesions greater than 0.5 cm, use caution with deeper lesions that have greater osseous involvement.

Coetzee and colleagues used the DeNovo graft to treat symptomatic osteochondral lesions on 24 ankles.8 They also note that 14 of the 24 ankles previously failed marrow stimulating surgeries.

The average lesion size was 125 ± 75 mm² and 7 ± 5 mm in depth. The average follow-up was 16.2 months. Seventy-eight percent of patients had good to excellent scores using the American Orthopedic Foot and Ankle Society Ankle-Hindfoot Scale. More specifically, 92 percent of patients with lesions that were 10 mm or larger and patients with lesions smaller than 15 mm demonstrated good to excellent results.

Exploring The Potential Of Orthobiologic Stem Cell Therapy

Without a doubt, the most exciting and promising innovation in tissue repair over the past few years has been stem cell therapy. Due to their pluripotent capabilities, mesenchymal stem cells are able to differentiate into multiple tissue types. For podiatric purposes, bone marrow aspirate typically originates at either the calcaneus or the tibia, where bone marrow is abundant. The goal with injection of this aspirate is to get as close to hyaline-like cartilage as possible.

In their study comparing patients treated with either microfracture alone or with a combination of arthroscopic marrow stimulation treatment and stem cell therapy, Kim and colleagues found significantly more favorable results in patients who had a stem cell supplemented procedure.9 This was especially true for lesions that were larger than 109 mm or those with subchondral cysts present.

In our practice at the University Foot and Ankle Institute, we have found success in enhancing other treatment modalities with stem cell therapy. For example, one can introduce bone marrow aspirate following a simple microfracture procedure or even add bone marrow aspirate to stimulate subchondral bone formation when retrograde drilling is required.

One may combine stem cell therapy with the aforementioned DeNovo graft, amnion membrane application or platelet rich plasma. Addition of an amnion membrane creates a solid scaffold onto which the stem cells can proliferate.10 Amnion membrane’s regenerative and anti-inflammatory properties are ideal for use in supporting the repair process of a talar lesion. Platelet rich plasma (PRP) contributes many growth factors to the area to again augment the healing process. One can even use PRP and bone marrow aspirate prior to casting during conservative treatment to increase the probability of cartilage restoration.

In Conclusion

Although there are many facets to the treatment of osteochondral lesions of the ankle and talus, the main factors to consider are the size of the lesion, the depth of the lesion and the desired activity level of the patient. With advancements in orthobiologic and regenerative therapies, the treatment of these lesions is being more customized to the needs of the individual patient.

In the future, cartilage replacement may be as simple as an injection or spray but for now, the stem cell options are helping us address lesions previously doomed to treatment failure.


Dr. Baravarian is an Assistant Clinical Professor at the UCLA School of Medicine. He is the Chief of Podiatric Foot and Ankle Surgery at the Santa Monica UCLA Medical Center and Orthopedic Hospital, and is the Director of the University Foot and Ankle Institute in Los Angeles.

Dr. Ben-Ad is a Fellow at University Foot and Ankle Institute in Los Angeles.

References:

1.  Oloff LM, Armstrong RA, Greenan D. Ankle arthroscopy: osteochondral defects. In: Chang TJ (ed): Master Techniques in Podiatric Surgery: The Foot and Ankle. First edition, Ch. 39, Lippincott, Williams and Wilkins, Philadelphia, 2005, pp. 499-509.
2. Whittaker JP, Smith G, Makwana M, et al. Early results of autologous chondrocyte implantation. J Bone Joint Surg [Br]. 2005; 87(2):179-183.
3. Walther M. Autologous chondrocyte transplantation. In: Easley ME, Wiesel SW (eds) Operative Techniques in Foot and Ankle Surgery. First edition, Lippincott, Williams and Wilkins, Philadelphia, 2011, pp. 808-817.
4. Gumann G. Mosiacplasty of the talus. In: Podiatry Institute Update, Ch. 35, Podiatry Institute Publishing, Tucker, Ga., 2005, pp. 191-194.
5. Scranton Jr. PE, Frey CC, Feder KS. Outcomes of osteochondral autograft transplantation for type- V cystic osteochondral lesions of the talus. J Bone Joint Surg [Br]. 2006; 88(5):614-619.
6. Sharpe JR, Ahmed SU, Fleetcroft JP, Martin R. The treatment of osteochondral lesions using a combination of autologous chodrocyte implantation and autograft. J Bone Joint Surg [Br]. 2005; 87(5):730-735.
7. Kruse DL, Ng A, Paden M, Stone PA. Arthroscopic DeNovo® NT juvenile allograft cartilage implantation in the talus: A case presentation. J Foot Ankle Surg. 2012; 51(2):218-221.
8. Coetzee JC, Giza E, Schon LC, et al. Treatment of osteochondral lesions of the talus with particulated juvenile cartilage. Foot Ankle Int. 2013; ebup ahead of print.
9. Kim YS, Park EH, Kim YC, Koh YG. Clinical outcomes of mesenchymal stem cell injection with arthroscopic treatment in older patients with osteochondral lesions of the talus. Am J Sports Med. 2013; 41(5):1090-9.
10. Niknejad H, Peirovi H, Jorjani M, et al. Properties of the amnion membrane for potential use in tissue engineering. Eur Cell Materials. 2008; 15:88-99.

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