Osteochondritis dissecans is an idiopathic lesion of the subchondral bone characterized by osseous resorption, collapse and sequestrum with possible involvement of the articular cartilage. Most frequently it involves the medial femoral condyle (70%), the lateral femoral condyle (20%), the patella (5% to 10%) and the trochlea (<1%). The etiology remains unclear; however, endocrine disorders, familial predisposition, vascular insufficiency, epiphyseal abnormalities and repetitive trauma have been investigated as concurrent causal factors.
The management of osteochondritis dissecans (OCD) requires a careful evaluation. Despite good results reported with conservative management, especially in skeletally immature patients with stable OCD, juvenile forms where a sclerotic rim is present have a tendency for poor clinical outcomes. Furthermore, the adult form, and in particular unstable lesions or those characterized by the presence of a loose body, have poor prognosis and therefore require a surgical approach to manage them. Drilling, open or arthroscopic fixation, fragment excision, microfractures, osteochondral grafting (with autograft or allograft) and autologous chondrocyte implantation (ACI) have been described as suitable treatment options.
New treatment strategies
Recently, the amazing progress achieved in the field of biomaterials and tissue engineering led to the development of new therapeutic strategies aimed at tissue regeneration. For this purpose, multi-layered biomimetic scaffolds and bone marrow-derived mesenchymal stem cells have been tested. The rationale for performing bone marrow-derived cell transplantation is based on the capability of these multipotent cells to differentiate and regenerate both the subchondral bone and the cartilaginous layer at the involved site.
Looking at the nanostructured scaffold, the rationale for its use is based on the capability of particular biomaterials to induce in situ tissue regeneration that is carried out by stem cells originating from the surrounding bone marrow.
Each surgical treatment has its pros and cons. A recent paper that my colleagues and I published in The Journal of Bone and Joint Surgery in 2012 reported the results of five different techniques to treat OCD. Herein is a brief description of those approaches, all of which can be considered to treat OCD.
Massive OAT procedure
The osteochondral autologous transplantation (OAT) procedure done for large OCD lesions involves a single surgery and takes advantage of implanting mature autologous bone and cartilage, which have excellent survival rates.
In particular, bone-to-bone healing allows a faster recovery period compared with cartilage regeneration procedures. On the other hand, the amount of graft that a donor site can provide is limited and that also determines the so-called “donor site” morbidity, of which surgeons should be aware. Furthermore, the technique requires an open surgical approach and there might be an anatomical discrepancy between the shapes of the donor site compared to the recipient site, which could prove problematic.
Particular care should also be taken during the implantation of the graft to ensure that once the graft is in place, its articular surface is not positioned higher or lower than the level of the surrounding articular cartilage.
Bone-cartilage paste graft
In the paste-graft approach surgical technique, cartilage harvested from the margin of the intercondylar notch and cancellous bone harvested from the proximal aspect of the tibia are morselized to obtain a paste. This paste is then used to cover the osteochondral defect.
An osteochondritis dissecans (OCD) lesion is seen prior to treatment.
Images: Kon E
The procedure involves a single surgical session, is inexpensive, uses an arthroscopic approach (with the exception of the mini-incision used to obtain bone from the proximal aspect of the tibia) and has minimal donor site morbidity. Despite these advantages, the repair tissue is of lesser quality compared to that of other procedures.
ACI plus bone graft
Performing a second-generation ACI procedure with bone grafting requires two arthroscopic surgical sessions. The first arthroscopic procedure is done both to harvest a cartilage sample for subsequent cultivation and to fill the bottom part of the lesion with autologous bone graft. During the second arthroscopic procedure, the surgeon implants the expanded cultured chondrocytes, which were seeded onto a hyaluronic acid (HA) membrane.
The capability of ACI to regenerate hyaline cartilage has been well proven, although it was originally done as an open procedure. Arthroscopic ACI approaches have since revealed results similar to those of the open implantation technique, without as much morbidity.
To date, some osteochondral biomimetic scaffolds have been tested in clinical practice. Among them, there is a three-layer scaffold developed by Fin-Ceramica Faenza Spa (Faenza, Italy) that has a porous 3-D composite structure that mimics the osteochondral anatomy.
The surgical technique used involves a single surgical procedure that does not require harvesting any autologous material or using any type of fixation device. The structure of this scaffold helps confine bone formation to the deepest portion of the lesion and cartilage regeneration to the surface of the area without the need for introducing any cell or growth-factor supplements to the surgical site.
Its disadvantages lie in the fact that the cost of this procedure is high, and a mini-arthrotomy must be performed to implant these biomimetic osteochondral scaffolds.
Marrow-derived cell transplantation
A bone marrow-derived cell transplantation procedure starts with the aspiration of bone marrow from the patient’s iliac crest. The aspirate is then immediately centrifuged to obtain bone marrow concentrate, which is loaded onto a membrane made of HA. The scaffold obtained is then placed on the lesion site that has been previously prepared.
The surgeon treated the OCD lesion by
implanting a biomimetic osteochondral
scaffold onto the lesion site, which was
Multiple overlapping stamps or patches of the membrane can be positioned in the defect. A layer of platelet-rich fibrin is ultimately applied over the membrane to provide growth factors at the site, as a further stimulus toward tissue regeneration. This entire procedure is performed arthroscopically and involves a single surgical session. What is more, the entire pool of regenerative cells being used is concentrated directly in the operating room at the time of surgery, which eliminates the need for separate steps for cell selection and expansion.
When compared to ACI, this technique is less expensive and it has further advantages because it requires a single surgical time.
The aforementioned 2012 study in The Journal of Bone and Joint Surgery assessed the clinical outcomes of these five different surgical techniques in patients affected by OCD of the knee, at a mean follow-up of 5 years.
No conclusive indication of the superiority of one technique over the other was demonstrated in this trial. Nevertheless, second-generation ACI in association with bone graft was confirmed as an extremely promising and reliable technique for cartilage repair in knees with OCD, with a trend toward achieving better results compared with non-regenerative techniques, such as massive OAT and bone-cartilage paste graft.
Concerning the new techniques of biomimetic osteochondral scaffolds and bone marrow-derived cell transplantation, they have provided results comparable to those of ACI and shown they are capable of overcoming some of the disadvantages of the older tissue regeneration techniques. However, since they were just recently developed and used in clinical practice, we only have results at short-term evaluations. Therefore, further studies are needed to confirm these encouraging, but preliminary results, and to determine whether longer follow-up will show similar results for all of these techniques or some evidence of the clear superiority of one of these options over the others.
Buda R. J Bone Joint Surg Am.
Filardo G. Knee
Filardo G. Arthroscopy
Kon E. Am J Sports Med
Kon E. J Bone Joint Surg Am
For more information:
Elizaveta Kon, MD, can be reached at II Orthopedics Clinic, Nano-Biotechnology Lab, Istituto Ortopedico Rizzoli, Via di Barbiano 1/10, Bologna, Italy; email: firstname.lastname@example.org.
Disclosure: Kon is a consultant to consulting for wFin-Ceramica Faenza SpA (Italy), is on the speaker’s bureau for Fidia, and is a paid consultant to and has stock options with Cartiheal.