In this issue of ORTHOPEDICS, Dr Minas discusses the challenges, techniques, and future of cartilage repair.
What is the goal of cartilage repair?
The goal of cartilage repair is to alleviate pain and improve function with a secondary goal of delaying the progression of osteoarthritis in the knee joint.
When is cartilage repair not a good option?
Cartilage repair is not a good option when the cause of the chondral defect is inflammatory such as infection, rheumatoid arthritis, or endstage disease with bone-against-bone changes in the tibiofemoral joint or the patellofemoral joint of the knee. This would be evidenced by loss of joint space on standing radiographs.
What role does rehabilitation play in cartilage repair?
Rehabilitation plays a major role in cartilage repair. Patients often present with chronic atrophy and dysfunction of the lower extremity secondary to a cartilage injury that has persisted and is disabling. After assessing the background factors for the cause of the chondral defect, such as tibiofemoral or patellofemoral malalignment, anterior cruciate ligament (ACL) insufficiency, or meniscal deficiency, reconstructions often will involve secondary procedures. The secondary adjuvant procedures are usually performed at the time of the cartilage repair procedure and may involve tibiofemoral osteotomy in approximately 30% of patients and patellofemoral tibial tubercle osteotomy in approximately 50% to 60% of patients. These large reconstructions require restoration of motion as the primary goal early postoperatively so that adhesions do not develop and delay healing or cause adhesions and fibrous repair to the chondral defects. Muscle tone restoration and functional rehabilitation with gait training is necessary. Progression of activity as time goes on over the first year to include nonimpact sporting activities such as cycling, skating, or swimming are important in the rehabilitation process.
What challenges are faced with cartilage repair?
Challenges that are faced in cartilage repair include an accurate diagnosis of the background factors responsible for the cartilage loss, surgical precision during the reconstruction, as well as rehabilitation.
Innovations are important for improving the predictability of the repair tissue to a hyaline-like tissue with every surgery as well as ease of application of the cartilage repair product to the defect site that can be done either minimally, invasively, or arthroscopically.
| || |
|Figure 1: Open appearance of a right knee in a man with disabling anterior knee pain with maltracking and chondral defects to the patella and trochlea. Figure 2: Same knee as Figure 1 after ACL to both surfaces with tibial tubercle osteotomy. |
Describe the latest cartilage repair techniques.
The latest cartilage repair techniques are primarily under investigation in the United States and Canada, but these have been readily available in Europe for as long as 10 years. The regulatory environment in Europe has been less stringent.
These products include cells delivered in a matrix made from hyaluronic acid, as well as collagen scaffolds that have precultured chondrocytes in them. These are delivered either minimally invasively with fibrin sealant fixatives to the subchondral bone or through minimal suturing techniques for defects that are slightly uncontained or on the patellar surfaces. These have made rehabilitation for patients in Europe much more predictable and less painful.
| || |
|Figure 3: Open appearance of the knee of a 22-year-old woman with dysplasia of the patellofemoral joint having failed prior tibial tubercle osteotomy and soft tissue balancing. She has advanced cartilage loss and persistent instability. Figure 4: Open appearance of the knee in Figure 3, after matched fresh osteochondral allograft patella and trochlea surfaces which restores normal anatomy to the knee. |
What does the future hold for cartilage repair?
The future for cartilage repair remains promising. Overcoming hurdles of regulatory guidelines and trials to bring these expensive technologies to the market are required. Techniques are becoming available to allow arthroscopically performed procedures with sophisticated products that are predictable in the quality of the cartilage repair tissue that develops.
These procedures will improve quality of life and function in younger patients. However, knee replacement surgery as the primary catabolic event allowing osteoarthritis to progress has not been discovered. We have found in our own series of cartilage repair patients with arthritic knees that the cartilage repair implants are durable; however, the remainder of the knee tends to continue to progress as time marches on and often knee replacement is required as a result of progression of disease of the osteoarthritic process. Much research needs to be continued in the basic science of osteoarthritis as well as the basic science of tissue-engineered products.
Dr Minas is from Brigham and Women’s Hospital, Boston, and the Cartilage Repair Center, Chestnut Hill, Massachusetts.
Dr Minas has no relevant financial relationships to disclose.
Correspondence should be addressed to: Tom Minas, MD, Brigham and Women’s Hospital, 850 Boylston St, Chestnut Hill, MA 02467 (TMINAS@partners.org).