Overview

Hyaline cartilage covers the articular surface, and plays an important role in decreasing friction and mechanical load on the joints. Damage to this cartilage can result in pain, swelling, and disabling joint dysfunction. Available strategies for managing cartilage defects include debridement or abrasion arthroplasty, subchondral drilling, and microfracture. These treatments are not always effective and, when they are, the benefits may not be long-lasting. Unsuccessfully treated cartilage damage in the knee can lead to progressive degenerative changes, which may eventually necessitate total knee replacement with a prosthetic device. However, an artificial joint generally lasts only 10 to 15 years, and total knee replacement is considered a poor option for people under the age of 50.^1,2,3,4 Autologous chondrocyte transplantation is currently under evaluation as a potential improvement over current strategies for treating knee cartilage defects.

Autologous chondrocyte transplantation uses a patient's own cartilage cells to repair traumatic damage to articular cartilage, and thereby improve joint function and reduce pain. The procedure involves collecting and producing an ex vivo culture of articular cartilage cells, which are implanted into the cartilage defect, where they contribute to regeneration and repair of the articular surface. Presently, there is only one company that produces ex vivo cell chondrocyte culture in the United States, and there is no indication that number will change in the near future.

Knee damage results from sports related injuries 28% of the time, injuries related to falls 25% of the time, injuries resulting from daily activities 22% of the time, and the remaining due to miscellaneous injuries.¹² Approximately 40% of patients having cartilage harvested for transplantation were on Workers' Compensation.¹² Nationally, approximately 650,000 reparative knee procedures are performed each year.^1,2,3,4 Of these, approximately 20,000 to 40,000 could qualify for autologous chondrocyte transplantation.^5,9 There have been 52 procedures done in Minnesota since 1995 and most have been at the University of Minnesota.⁵

Findings

Evidence regarding the efficacy of autologous chondrocyte transplantation in human subjects is limited. Data suggest that the technique is safe and effective in reducing symptoms of cartilage damage in the knee in up to 80% of patients with single defects of the femoral condyle.^2,6 The failure rate is approximately 10%.⁵ Complications have been limited to loosening of the transplant tissue, and the return of pain and joint-locking due to the development of fibrous tissue. Neither complication usually leaves the patient in a condition worse than the pre-transplantation state. Non-compliance with a required post-surgical therapy regimen has been associated with procedure failure. A registry is kept by the National Orthopedic Surgeons Association which provides data on patients who have been followed for up to four years after implantation.² However, due to the limited number of procedures that have been performed, the registry has little data on long-term outcomes. In addition, there have been no systematic comparisons between autologous chondrocyte transplantation and other treatments for traumatic cartilage injury.

While specific patient selection criteria have yet to be definitively established, expert opinions indicate that autologous chondrocyte transplantation is most appropriate in individuals between the ages of 15 and 55 years old who have full thickness, localized lesions of the femoral condyles, who do not have joint malalignment or generalized chondromalacia of the tibia, and who are willing and able to undergo rigorous physical therapy.^6,8,9

When comparing the cost effectiveness of autologous chondrocyte transplantation to alternative treatments, including total knee replacement, there are many influencing factors such as age, type of work, degree of disability, and amount of physical therapy required. Since little data is available on the long-term durability of the transplant it is uncertain at this time if it is cost effective.⁷ The cost of the cell culturing service for the autologous chondrocyte implant is $11,500. The cost for the procedure varies depending upon provider and facility fees. There is also a wide variation among third party payors in terms of the degree of coverage provided.⁵ Currently, the procedure is considerably more expensive than alternative treatments for knee damage like debridement, subchondral drilling, and microfracture techniques. However, these alternative treatments are not always effective and may not be long lasting.^10,11,12

Conclusions

While autologous chondrocyte transplantation appears to be a promising alternative to standard approaches for managing cartilage defects of the knee, the efficacy of this procedure has not been firmly established and the long-term functional outcome is unknown. Well-designed, randomized, controlled trials are needed to prove efficacy, define patient selection criteria, and determine long-term benefits relative to alternative strategies. At the present time, autologous chondrocyte transplantation is a reasonable therapeutic alternative only for carefully selected patients.

References

1.

Brittberg M, Lindahl A, Nilsson A, et al Treatment of Deep Cartilage Defects in the Knee With Autologous Chondrocyte Transplantation. N Engl J Med. 1994;331:–. [PubMed: 8078550]

2.

Genzyme Corporation website. Carticel – Genzyme Tissue Repair. Updated 1998. http://www​.genzyme.com​/prodserv/tissue_repair​/carticel/welcome.htm.

3.

Mandelbaum BR, Browne JE, Fu F, et al Articular Cartilage Lesions of the Knee. Am J Sports Med. 1998;26:–. [PubMed: 9850792]

4.

Gilbert JE Current Treatment Options for the Restoration of Articular Cartilage. Am J Knee Surg. 1998;11:–. [PubMed: 9533054]

5.

Conversation with Genzyme Corporation representative on May 5, 1999.

6.

Gillogly SD, Voight M, Blackburn T Treatment of Articular Cartilage Defects of the Knee with Autologous Chondrocyte Implantation. J Orthop Sports Phys Ther. 1998;28:–. [PubMed: 9785259]

7.

Buckwalter JA Cartilage researchers tell progress. Technologies hold promise but caution is urged April 1, 1996 AAOS Bulletin online 199644http://www.aaos.org/wordhtml/bulletin/april96/sympos.htm.

8.

Peterson L Autologous Chondrocyte Transplantation: 2–10 Year Follow-up in 219 Patients. Presentation Abstract: American Academy of Orthopedic Surgeons Annual Meeting, March, 1998. New Orleans, Louisiana, USA.

9.

Curl WW, Krome J, Gordon ES, et al Cartilage Injuries: A review of 31,516 Knee Arthroscopies. Arthroscopy: The J Arthroscopy and Related Surg. 1997;13:–. [PubMed: 9276052]

10.

Minas T Management of the Arthritic Knee Without Total Knee Replacement: What Works, What Doesn't Work, What the Future Holds, presentation abstract American Academy of Orthopedic Surgeons Annual Meeting, March, 1998. New Orleans, Louisiana.

11.

Minas T Chondrocyte Implantation in the Repair of Chondral Lesions of the Knee: Economics and Quality of Life. Am J Orthop. 1998;27:–. [PubMed: 9839958]

12.

Cartilage Repair Registry-Periodic Report: Volume 5, January, 1999.