Defect size, other considerations important in choosing a cartilage repair technique

Axial alignment is the number one background factor that must be considered to have a successful repair.

To choose the appropriate cartilage repair technique, surgeons should consider the cause of chondral defects and assess a checklist of background factors, according to Tom Minas, MD, attending orthopedic surgeon and director of the Cartilage Repair Center at Brigham & Women’s Hospital in Boston.

Minas discussed these considerations, as well as the benefits and advantages of various techniques, at the 26th Annual Current Concepts in Joint Replacement Winter Meeting in Orlando.

Axial alignment

The most important component on the list of background factors that will make the cartilage repair successful is axial alignment, according to Minas. Additional factors to consider are joint stability, defect size and the possibility of an absent meniscus or a predisposition to osteoarthritis.

“If you have a small defect, probably either debridement or any of the marrow stimulation repair techniques are appropriate,” Minas said. “But with large defects, we need something visco-mechanically sound, that will not bottom out and cause pain or further progression of the disease.”

Minas told attendees at the 26th Annual Current Concepts in Joint Replacement Winter Meeting that osteochondral autograft transfer systems are his procedure of choice for defects smaller than 1.5 cm. Image: Rapp SM, Orthopedics Today

The first technique he discussed was microfracture. The main components of microfracture, according to Minas, are removing the subchondral bone tidemark, obtaining vertical walls and developing pick holes that allow marrow cells to surface. He explained that with rehabilitation involving continuous passive motion-protected weight-bearing, this technique can be successful for small defects. Previous research has shown that after microfracture, about two-thirds of patients see improvement with activities of daily living and sports, while another one-third see no improvement or may even worsen.

Minas said osteochondral autograft transfer systems are his procedure of choice for defects smaller than 1.5 cm. “The arthroscopic technique is difficult, and central weightbearing condyles should be done with an open technique if necessary,” he said.

He also cautioned that there are often later problems with cyst formation and subchondral bone and resorption with multiple defects. However, “if technically performed well, your results are about 90% good or excellent,” Minas said.

ACI

Results with autologous chondrocyte implantation grafting are generally favorable, but it is a technique-sensitive procedure, and Minas said surgeons should consider the postoperative problems of graft overgrowth in cases where a periosteum is used.

“The technique involves arthroscopic biopsy of the cartilage, cell culturing and a second-stage open implantation,” Minas said. “With these techniques, the results are quite predictable in weight-bearing condyles with 90% good and excellent results. In the patella, if you address realignment, you can achieve 80% good and excellent results.”

New technology

A new technology currently in use in Italy is pre-cultured, cell-seeded membranes.

“A big advantage here is that the cells are preloaded in the membrane and it can be performed by arthroscopic techniques for lesions up to about 3 cm²,” he said.

Another new technology used in Israel, which involves hyaluronan and fibrin with a fibroblastic growth factor variant, allows cells to mature before implantation, he noted.

Finally, tissue-engineered cartilage is now in stage-3 clinical trials in the United States, Minas said. This technology involves incubation in a pressure transducer, cartilage is nearly mature at 6 weeks, and it can be implanted directly into a defect. – by Tina DiMarcantonio

References:

• Minas T. Cartilage restoration therapies: Resurfacing potholes. Presented at the 26th Annual CCJR Winter Meeting. Dec. 9-12, 2009. Orlando, Fla.
• Tom Minas, MD, attending orthopedic surgeon, director of the cartilage repair center at Brigham & Women’s Hospital, Boston, can be reached at 850 Boylston St, Suite 112, Chestnut Hill, MA 02467; e-mail: tminas@partners.org.

This information will impact clinical practice by making orthopedic surgeons aware that these technologies are available. Patients can be referred to centers where they practice those techniques. After arthroscoping a patient and seeing a defect, rather than telling them to live with it or there is nothing that can be done, orthopedic surgeons are now aware that there are centers where these technologies are being practiced.

— Allan E. Gross, MD, FRCSC
Chief, Division of Orthopedic Surgery, Mount Sinai Hospital, Toronto
Professor, Department of Surgery, University of Toronto