New surgical tools, biologics being explored for meniscal tears

Meniscal preservation and regeneration technologies are slowly gaining acceptance as viable treatments.

Issue: April 2004

AAOS San Francisco [logo] SAN FRANCISCO — In the next few years, orthopedic surgeons will be equipped with better techniques and biological solutions to repair, replace and/or regenerate the meniscus, especially for baby boomers seeking to remain active for many more years.

“There are nine [meniscal] resections to every one repair, and the overwhelming number of orthopedists continue to remove the meniscus than repair it,” said Nicholas A. Sgaglione, MD, chief of the division of sports medicine at North Shore University Hospital, Manhasset, N.Y. and associate professor of orthopedics at Albert Einstein College of Medicine.

“Unfortunately for some patients, if you remove their meniscus, they will go on to develop degenerative arthritis. The vast number of patients who want meniscal surgery are getting a resection, and we are hoping we can change that ratio.”

In the next five to 10 years, a less-invasive biological approach may become the treatment of choice, he said.

“Novel scaffolds are very promising, as well as cell-based therapies and bioactive factors,” Sgaglione said during a media briefing here at the American Academy of Orthopaedic Surgeons 71st Annual Meeting.

What is new, according to Sgaglione, is the ability to perform arthroscopic meniscal repair using an all-inside device and obtain a vertical mattress suture configuration, which has been shown to be one of the strongest constructs in repairing meniscus tears.

“We are on the cusp of an explosion in technology related to platelet-rich plasma,” he said. “We are able to take the patients’ own blood, spin it down in a centrifuge in the operating room, obtain ultra-concentrated platelets with attached growth factors and use these growth factors to promote healing. It’s essentially one-stop biological manipulation and healing amplification in your operating room.

“I find that autologous, platelet-rich plasma is one of the most practical, promising and realistic technologies we have today — more so than something like ‘explant’ genetic engineering, which is probably 10 or more years away.”

Treating the problem tears

Sgaglione said knee surgeons today are challenged to repair meniscal tears that are considered irreparable or “geometrically challenged,” as well as complex red/white or white/white tears that have an inadequate blood supply.

“If we can gain access to the areas that are hypovascular, we can amplify healing,” he said. “By drilling tunnels during anterior cruciate ligament reconstruction, we’re producing and releasing blood into the joint, and this blood from the marrow cavity that enters the tunnels is rich in mesenchymal stem cells and progenitor cells. This creates a broth, if you will, or a healing milieu that improves healing rates.”

Sgaglione uses fibrin clot from the patient, which he stirs with the patient’s blood to form an adhesive clot of ultra concentrated platelets. He places the clot during the arthroscopic procedure to repair isolated meniscal tears.

“We now have the ability to use intraoperative blood, spin it down in a centrifuge and take the cells off,” he said. The result is a “supernatant” that includes the fibrin matrix that is rich in platelets and growth factors, particularly platelet-derived growth factor, transforming growth factor-ß, endothelial growth factors and vasculo-endothelial growth factor.

Bioactive sutures

Compelling preclinical work on the use of angiogenic/biologic sutures is currently being carried out. These sutures are coated with factors and various chemicals that produce an angiogenic response. These sutures help improve vascularity in meniscal regions with poor blood supply, he said.

“I find that autologous, platelet-rich plasma is one of the most practical, promising and realistic technologies we have today.”
— Nicholas A. Sgaglione

Many surgeons are also considering gene-modified tissue engineering measures to help restore the meniscus. In early studies, investigators took meniscal fibrochondrocytes or mesenchymal stem cells from the bone marrow. “We would then seed these cells onto a collagen scaffold,” he said. Today, “We can use some of our platelet-rich constructs, including various kinds of bioactive peptides, to amplify healing in this group.”

Dr. Dan Grande and colleagues at North Shore University Hospital have used insulin-like growth factor-transduced mesenchymal stem cells to implant avascular bucket-handle tears in a bovine model and then repair them using an arrow or polylactic implant. In animals whose experimental defect was treated with cells transduced or transfected with the insulin-like growth factor, “ a robust hypercellular healing response with evidence of migration into the defect was noted.”

Despite researchers’ excitement about the novel technologies, there is still much to learn.

“Although we would like to think we are at the point where we can control various types of growth factors and bioactive peptides, we’re really in our infancy in terms of controlling dosing, scheduling, release and half-life of many of these peptides,” he said. “They have been assayed, but they may not be able to be sustained over time in the knee joint. That’s something that needs much more work and investigation.”

Likewise, “Many of the things we do have to be documented as far as chondroprotection is concerned. Are we making a difference? Are we protecting the articular cartilage from later degeneration and osteoarthritis?” he asked.

“Most importantly, in an era in which medical costs have been ratcheted down, we have to face the fact that cost-effective measures are just as important as some of the more extravagant gene therapeutic measures. We need to consider cost-effective practicality in treating our patients clinically.”