Art of achieving an optimal cartilage repair depends on surgeon, technique

Options are expanding; the effective ones involve a biologically, mechanically favorable environment.

Issue: July 2007

Cartilage repair techniques, including arthroscopic debridement, biologic approaches and synthetic solutions, provide orthopedic surgeons with a full range of options for treating patients.

According to cartilage repair experts Brian J. Cole, MD, MBA, and Steven P. Arnoczky, DVM, the most effective cartilage treatments available offer advantages for relieving pain and restoring function, but they differ considerably.

Osteochondral autografting works well in high demand patients who have smaller cartilage defects.

Images: Cole BJ

Autologous chondrocyte implantation provides access to chondro-potential cells and therefore has an increased chance of generating high quality cartilage-like tissue.

Each cartilage repair method is indicated for specific-sized lesions and benefits different patients according to activity level. Nearly all of them are contraindicated for bipolar lesions and degenerative joint disease, Cole said.

Confusing matters further, “This pipeline of options is growing exponentially,” he said at the American Orthopaedic Society for Sports Medicine Specialty Day Meeting.

Cole and Arnoczky agreed that surgeons need to select appropriate surgical solutions on a case-by-case basis and realize that the result of cartilage repair varies according to the technique.

The goal that most surgeons are trying to achieve with today’s cartilage repair techniques is the restoration of a smooth, durable, articulating surface,” Arnoczky told Orthopedics Today. “However, this is not always an easily attainable goal.”

No current cartilage repair technique regenerates cartilage. They only repair or replace it through a natural healing process that requires the maturation of fibrocartilaginous repair tissue over time, Arnoczky explained.

Histological studies show that repair techniques from microfracture to autologous chondrocyte implantation (ACI) produce a hybrid-like fibrocartilage and that the quality of that fibrocartilaginous repair tissue can vary. However, clinicians can optimize the quality of the repair tissue that results when they follow basic science principles, Arnoczky said.

“Surgeons who can adhere to those principles have a better chance of producing the best quality repair tissue,” he said.

Key principles

Arnoczky said the basic science principles for optimizing cartilage repair are as follows:

providing access to chondro-potential cells like mesenchymal stem cells or chondrocytes;
providing access bioactive factors which are present in synovial fluid or in a marrow-derived fibrin clot; and
creation of a mechanically and biologically favorable environment.

Arnoczky said surgeons should use a repair technique that incorporates the first two principles, but realize that they ultimately have the most control over the third principle: the mechanical environment of the joint.

“It’s not just resurfacing the joint, but also optimizing joint mechanics, which may involve performing an ACL repair, meniscal allograft or tibial osteotomy,” he said.

“When you have a good mechanical environment, you’re also encouraging better nourishment and faster maturation of the repair tissue, so you also end up improving the biological environment as well,” Arnoczky said.

Not a sure thing

From the start of any primary cartilage repair, the clinician must be armed with a revision plan because “up to 25% of these patients may fail,” Cole said.

Among the mainstays of cartilage repair, microfracture is indicated for lower-demand patients with large lesions or higher-demand patients with smaller lesions. “It’s necessary to violate the calcified layer … in order to have the best incorporation and the highest degree of fibrocartilage fill,” Cole said.

Patients with classic lesions up to 10 cm² with limited bone loss will respond well to ACI — an excellent option for the patellofemoral joint, he said.

Osteochondral autografts provide a first- or second-line treatment for higher-demand patients with small defects. However, Cole urged surgeons to gently impact them to reduce the mechanical load placed on the grafts.

For deeper, larger or traumatic lesions like osteochondritis dissecans, Cole recommended osteochondral allografts no more than 28 days old, which he pulsatile-lavages to minimize any immune response.

Chondrocytes can survive in osteochondral allografts, based on results of recently published studies.

For more information:

Steven P. Arnoczky, DVM, director of the Laboratory for Comparative Orthopedic Research, can be reached at the College of Veterinary Medicine, Michigan State University, G-387 Veterinary Medical Center, East Lansing, MI 48824; 517-353-8929; e-mail: arnoczky@cvm.msu.edu. He has no financial conflicts to disclose.

Brian J. Cole, MD, MBA, can be reached at the Rush Cartilage Restoration Center, Rush University Medical Center, 1725 W. Harrison St., #1063, Chicago, IL 60612; 312-432-2300; e-mail: bcole@rushortho.com. He is a consultant to Arthrex and Genzyme.

Reference:

Cole BJ. Articular cartilage restoration: Overview. Presented at the American Orthopaedic Society for Sports Medicine Specialty Day Meeting. Feb. 17, 2007. San Diego.