This article is more than 5 years old. Information may no longer be current.
Surgeons should choose carefully among treatments for osteochondral defects
ACI options mount with new and future advances, including synthetic plugs and scaffolds.
When filling osteochondral defects in the knee, surgeons have a list of treatment options to choose from and more options are in the works.
Giles R. Scuderi, MD, reviewed the advantages, disadvantages and indications of existing procedures at the annual Current Concepts in Joint Replacement winter meeting.
“There are various ways of … addressing these osteochondral defects,” Scuderi said. “You need to know your options, the size of the lesions, know your patients [and] their expectations, as well as your own.”
Current treatment options are typically cartilage enhancement procedures, in which surgeons stimulate the cartilage to grow or replace it. “Most of the reports will tell us that at least three-fourths of the patients, if not more, are successful [with these treatments],” Scuderi said.
Microfracture
|
|
Using the microfracture technique, which stimulates cartilage repair, surgeons penetrate the subchondral bone and try to release the mesenchymal cells to form a fibrocartilage cap, Scuderi said.
“You debride the edges so they’re smooth, and then with the awl you penetrate the subchondral bone until you get bleeding from the microvascularity. This, again, stimulates the fibrocartilage,” he said.
Studies on this technique revealed relatively good results. In 2003, J. Richard Steadman, MD, and colleagues reported in Arthroscopy that 80% of their patients treated with the technique improved by 7-year follow-up. However, the technique has limitations.
“Basically it’s for the younger patients with small lesions, and remember, you are only replacing that defect with fibrocartilage,” Scuderi said. In addition, patients typically take 6 months to return to full activity.
With osteochondral autologous transplantation (OATS), surgeons transfer osteochondral plugs from one area of the knee to another. This procedure is ideal for the smaller osteochondritis dissecans (OCD) lesions with focal defects in younger patients, aged 15 years to 45 years, Scuderi said.
This single-stage procedure “is cost-effective and has a quicker recovery because you are basically transferring the cartilage and bone from one area to another,” Scuderi said. “The reports in the literature show about 80% to 90% success for femoral condylar lesions.”
OATS also has disadvantages, including a high technical demand of the surgeon, donor-site morbidity, differences in cartilage structure, and the potential for cell death at the periphery of the plug, Scuderi said.
In 2001, John G. Lane, MD, and colleagues found that surgeons achieved bone healing with the plug transfer, and they were able to restore the surface.
“But you get these [full-thickness] clefts between the plug and the adjacent articular cartilage,” Scuderi said. “The histology shows 95% survival [of chondrocytes], and this has been documented at about 2 years [postop].”
|
Images: Caborn D |
|
Image: Scuderi GR |
Osteochondral allograft
For larger defects — including those greater than 3 cm to 4 cm in diameter — Scuderi recommends osteochondral allograft transplantation. With this technique, surgeons can achieve bone-to-bone healing, they can transfer hyaline cartilage, and the cartilage and bone become a single unit. Surgeons can also use the technique to treat larger lesions and those with bone loss, Scuderi said.
The disadvantages, however, are procurement and availability of the specimens, a long rehabilitation process, nonweight-bearing for 3 months and the removal of healthy bone and tissue when contouring the areas for plug placement.
“The most important issue is the recent controversy about disease transmission, but, really, you need to know your source,” Scuderi said.
In one study on this technique, Constance R. Chu, MD, and colleagues found that 77% of patients reported good to excellent results.
This investigation and some others have shown better results with unicondylar lesions, rather than those that are bicondylar, Scuderi said.
“The results are best with the lesions on the medial or lateral femoral condyle and [when the technique is] used in conjunction with an osteotomy to help unload it when you have limb malalignment,” he said.
Surgeons indicate autologous chondrocyte implantation (ACI) for patients with focal full-thickness chondral defects, primarily in the femoral condyles and trochlea, Scuderi said. The procedure is appropriate for patients aged 15 years to 50 years and those with OCD lesions and less than 8 mm of bone loss.
Advantages of ACI include the ability to use autologous chondrocytes, hyaline-like repair tissue, its appropriateness for larger lesions, and better subchondral bone preservation. Early results from three separate studies demonstrated 80% to 90% good-to-excellent results for femoral condyle lesions.
“The disadvantages: It’s a two-staged procedure, and arthrotomy is required for the second stage,” Scuderi said. “It’s a very meticulous technique, and it’s time-consuming, expensive, and [requires] a little bit more protracted rehabilitation.”
Reoperation rates range from 5% to 10%, usually for periosteal hypertrophy, adhesions and arthrofibrosis.
New and future advances
New synthetic plugs also offer an option for filling osteochondral defects, and address the three critical parts of osteochondral healing: articular cartilage, the tidemark and the subchondral bone, Scuderi said. Each of these layers is designed to match physical and mechanical properties of the adjacent bone.
Future developments include scaffolds with growth factors and synthetic and biologic matrices.
“Some of the desirable features that we’ll look for [are] good internal fixation to the hosts; and the substances should be biodegradable and encourage both cell ingrowth and attachment to the area,” Scuderi said.
New scaffolds on the market for ACI will optimize cell lines and molecular markers.
“These are going to be seeded 3-D grafts that are going to improve chondrogenesis,” Scuderi said. “There’ll be no periosteal patches, no suturing, and they will be introduced to the knee arthroscopically.”
For more information:
- Scuderi GR. Cartilage resurfacing: Filling potholes. #64. Presented at the 23rd Annual Current Concepts in Joint Replacement Winter 2006 Meeting. Dec. 13-16, 2006. Orlando, Fla.
- Giles R. Scuderi, MD, Insall Scott Kelly Institute, 210 East 64th Street, 4th Floor, New York, NY 10021; 212 434-4310; GRScuderi@aol.com. He has no direct financial interest in the products discussed in this article. He is a consultant for Zimmer Inc.