Cartilage Restoration refers to a group of surgical techniques designed to treat articular cartilage injuries by either repairing or replacing the damaged cartilage. Specific procedures include microfracture, autologous chondrocyte implantation, and osteochondral grafting. This is an evolving area of sports medicine including research into mesynchymal stem cell therapies.
Articular cartilage refers to the smooth covering of joint surfaces. Normal cartilage allows the smooth, painless motion of joints with minimal friction. The inherent problem in treating articular cartilage injuries is that it has poor healing capacity. Articular cartilage lacks adequate blood supply and tends to form fibrocartilage when it does heal. Fibrocartilage is less durable and has poorer mechanical properties than hyaline cartilage, which makes up normal articular cartilage.
Articular cartilage injuries can occur from acute trauma, but more commonly are secondary to gradual degeneration (arthritis). The traumatic injuries often occur in athletics and in younger age groups. Current cartilage restoration procedures are aimed at treating focal cartilage defects, which typically result from the acute injuries. The indications for treatment of cartilage injuries are very specific. Cartilage restoration procedures for arthritic joints with diffuse abnormality of the articular cartilage are unlikely to be successful.
MicrofractureMicrofracture involves removal of the damaged cartilage and the creation of multiple holes in the underlying bone using a sharp awl. The procedure is performed arthroscopically. The holes created are designed to deliver blood supply to the region, thus allowing new cartilage to form within the defect. As with all cartilage restoration procedures, the best candidates for successful microfracture surgery are younger patients with an isolated cartilage defect. This procedure has been performed on many elite level athletes. Please see Post-operative Instructions: Microfracture and Rehab Guidelines: Microfracture for more details.
Autologous Chondrocyte Implantation (ACI)ACI is a two stage procedure. The first stage involves arthroscopic surgery to harvest cartilage from a healthy, non-weight bearing area of the knee joint. The cartilage cells or chondrocytes are then sent to a lab where they will be cultured and multiply over 3-5 weeks.
The second stage is performed as an open procedure, not arthroscopically. The periosteum that covers the tibia is removed and sutured over the injured cartilage. The cultured chondrocytes are then injected beneath this patch where they will form new cartilage. ACI is most commonly performed in younger patients with large (>2 cm), focal articular cartilage defects.
Osteochondral GraftingOsteochondral grafting includes removing a plug of damaged cartilage along with the underlying bone. This is replaced by a healthy plug either taken from the patient’s own knee (autograft) or taken from a cadaver (allograft). Autograft is limited in scope because the plug must come from an area that has minimal joint contact and is non-weight bearing. This is typically performed for smaller articular cartilage defects.
Allograft procedures are typically reserved for larger defects and often defects that include cartilage and underlying bone. Grafts are sterilized and tested for possible transmission of infection. This is also performed as an open procedure.
Stem CellsStem cells are undifferentiated or still have the potential to develop into a specific type of cell. They can be obtained from bone marrow and other human tissues. Stem cells may have the ability to differentiate into normal hyaline cartilage. This is a current area of research in orthopaedics without clinical results as of yet. There are some clinical trials in process, but this is otherwise currently considered experimental.
RehabilitationRehabilitation plays a significant role in cartilage restoration surgery. A 6-8 week period of non-weight bearing with crutches is typically recommended after these procedures in order to protect the newly forming cartilage. A CPM or continuous passive motion machine is also commonly used post-operatively as it may stimulate growth of the new cartilage. Specific instructions and return to activities will vary based on the injury and procedure performed. This should be discussed pre-operatively with your orthopedic surgeon.
Orthopaedic surgeons continue to research techniques into which they might improve the quality of life of those with cartilage restoration needs. This information is a brief summary regarding treatment of cartilage injuries and not intended to be a complete resource. Specific questions and surgical details should be discussed with your surgeon as opinions may vary. An appointment can be scheduled with Dr. Michael Burris, a subspecialty trained and local Austin sports medicine physician, to see what might be appropriate for your situation.
Resources on Cartilage Restoration
- Articular Cartilage Restoration - The American Academy of Orthopaedic Surgeons
- Cartilage Research Foundation (CRF) - Founded in 2002 by a select group of cartilage restoration surgeons who have jointly performed more than 2,000 cartilage restoration surgeries and organized as a nonprofit corporation in an effort to collectively further the treatment and outcomes of cartilage restoration procedures.