Introduction to articular cartilage repair

Dr Hambly clarifies the difference between articular cartilage and meniscus cartilage.

First published in 2008, and reviewed August 2023 by Dr Sheila Strover (Clinical Editor)

 

Mention knee cartilage to most people and they will tend to think about the wedge shaped shockabsorbers of the knee - the menisci.

However, there is another form of cartilage in the knee that causes knee problems - the articular cartilage - the white gristle covering the adjacent surfaces of 'articulations' or 'joints'.

Articular cartilage has been known to be a potential problem for quite a while! In Roman times after gladiators had 'dissected' each other fighting, their physician, Galen, witnessed human tendons, cartilage and ligaments and made the observation that 'athletes get arthritis'. Two hundred and fifty years ago a famous anatomist noted that 'ulcerated cartilage is a troublesome thing and once destroyed, is not repaired' (Hunter 1743). Thousands of people each year experience symptoms related to chondral (joint cartilage) and osteochondral (joint cartilage and bone) defects.

We are in the 21st century now so why does articular cartilage damage continue to be such a 'troublesome thing'? Well to give you a better insight into why that is the case it is useful for you to know a bit more about the structure of articular cartilage, the role that it performs and how it gets damaged.

 

What is articular cartilage?

Articular cartilage is found in all moving joints in the body (synovial joints) and its role is to protect the bones by keeping the surfaces of the bones apart from each other, to absorb shock and to help make movement smooth. Articular cartilage does this by providing a protective, wear resistant surface to the end of the moving bones. In the knee articular cartilage covers the ends of the femur (medial femoral condyle, lateral femoral condyle and the trochlea), the top of the tibia (tibial plateau) and the back of the patella.

 

This image of the rounded end of the femur bone show the white shiny articular cartilage.

 

 

 

This second image shows a close up of the area circled in red.

 

 

Articular cartilage is a particular type of cartilage called hyaline cartilage (derived from the Greek word hyalos, meaning glass). Hyaline cartilage is a hard, white shiny material with a unique structure that creates a surface that allows the bones to glide easily past each other as the knee joint moves. It varies between individuals but it is generally between 2 and 4mm in depth in the knee and it has an amazingly low coefficient of friction - just 1/15th that of ice - now that's very slippery. The special nature of this material, however, also makes it particularly vulnerable once it becomes damaged.

 

How can you damage articular cartilage?

Articular cartilage injuries are common. The normal structure and function of articular cartilage can be upset relatively easily and damage to the articular cartilage often results. There are several ways in which your articular cartilage can become damaged.

 

1. A sudden direct blow to the cartilage (traumatic) e.g. a high-energy injury such as a bad fall on directly onto your knee or during sporting activities.
2. Slow damage to the cartilage following a knee injury (post-traumatic).
3. Wear and tear over time (degenerative joint disease or DJD) - especially when there is malalignment or instability in the joint and/or if you are overweight.
4. Immobilisation for long periods of time as articular cartilage is nourished by joint movement so immobilisation can result in damage.
5. Osteochondritis dissecans is a condition that is thought to occur due to poor blood supply to the underlying bone resulting in a piece of cartilage and subchondral bone separating from the articular surface.

 

It is possible to just damage the articular cartilage on its own but you often find articular cartilage damage in conjunction with injury to other tissues in the knee particularly ligaments and menisci. If you have had a previous injury to your ligaments and/or menisci then you are at greater risk of articular cartilage damage due to the altered mechanics of the joint even if the original injury has been successfully repaired eg anterior cruciate ligament reconstruction.

A general misconception is that articular cartilage damage and osteoarthritis only affect people in their 50's or older. Although there is a greater incidence of articular cartilage problems in this age group young people damage their articular cartilage too, especially in sports or via osteochondritis dissecans.

If the knee joint is out of position (mal-aligned), unstable or if the knee cap is being pulled to one side too much stress could be placed on particular parts of the joint surface and this is known to accelerate degenerative changes in the articular cartilage. This has important implications for cartilage repair surgery that will be discussed later.

 

Journal publications

Alford, J. W. and Cole, B. J. (2005) Cartilage restoration, Part 1: Basic science, historical perspective, patient evaluation, and treatment options. Am J Sports Med, 33(2): 295-306.

Alford, J. W. and Cole, B. J. (2005) Cartilage Restoration, Part 2: Techniques, Outcomes, and Future Directions. Am J Sports Med, 33(3): 443-460.

Dunn, W. R., Lyman, S., Lincoln, A. E., Amoroso, P. J., Wickiewicz, T. and Marx, R. G. (2004) The effect of anterior cruciate ligament reconstruction on the risk of knee reinjury. Am J Sports Med, 32(8): 1906-14.

Brittberg, M., Peterson, L., Sjogren-Jansson, E., Tallheden, T. and Lindahl, A. (2003) Articular cartilage engineering with autologous chondrocyte transplantation. A review of recent developments. J Bone Joint Surg Am, 85-A Suppl 3109-15.

Hambly, K., Bobic, V., Wondrasch, B., Van Assche, D. and Marlovits, S. (2006) Autologous chondrocyte implantation postoperative care and rehabilitation: Science and practice. Am J Sports Med 34(6):1020-1038

Jakobsen, R. B., Engebretsen, L. and Slauterbeck, J. R. (2005) An analysis of the quality of cartilage repair studies. J Bone Joint Surg Am, 87(10): 2232-2239.

Knutsen, G., Engebretsen, L., Ludvigsen, T. C., Drogset, J. O., Grontvedt, T., Solheim, E., Strand, T., Roberts, S., Isaksen, V. and Johansen, O. (2004) Autologous Chondrocyte Implantation Compared with Microfracture in the Knee. A Randomized Trial. J Bone Joint Surg Am, 86(3): 455-464.

Mithofer, K., Peterson, L., Mandelbaum, B. R. and Minas, T. (2005) Articular cartilage repair in soccer players with autologous chondrocyte transplantation: functional outcome and return to competition. Am J Sports Med, 33(11): 1639-1646.

Peterson, L., Brittberg, M., Kiviranta, I., Akerlund, E. L. and Lindahl, A. (2002) Autologous chondrocyte transplantation. Biomechanics and long-term durability. Am J Sports Med, 30(1): 2-12.

Mandelbaum, B. R., Browne, J. E., Fu, F., Micheli, L., Mosely, J. B., Jr., Erggelet, C., Minas, T. and Peterson, L. (1998) Articular cartilage lesions of the knee. Am J Sports Med, 26(6): 853-61.

Shelbourne, K. D., Jari, S. and Gray, T. (2003) Outcome of Untreated Traumatic Articular Cartilage Defects of the Knee: A Natural History Study. J Bone Joint Surg Am, 85(90002): 8-16.

Steadman, J. R., Briggs, K. K., Rodrigo, J. J., Kocher, M. S., Gill, T. J. and Rodkey, W. G. (2003) Outcomes of microfracture for traumatic chondral defects of the knee: average 11-year follow-up. Arthroscopy, 19(5): 477-84.

Wang, Y., Ding, C., Wluka, A. E., Davis, S., Ebeling, P. R., Jones, G. and Cicuttini, F. M. (2006) Factors affecting progression of knee cartilage defects in normal subjects over 2 years. Rheumatology, 45(1): 79-84.

Wroble, R. R. (2000) Articular Cartilage Injury and Autologous Chondrocyte Implantation: Which Patients Might Benefit? Physican and Sportsmedicine, 28(11).

Additional Information

Web articles

Bobic, V. ISAKOS Current Concepts. The utilisation of osteochondral autografts in the treatment of articular cartilage lesions.

http://www.isakos.com/innovations/oats.aspx

Diduch, D.R. & Cohen, S.B. Joint repair: Treatment options for articular cartilage injury.

http://www.orthopedictechreview.com/issues/novdec02/pg24.htm

Johnson, D. Articular cartilage update

http://www.medscape.com/viewarticle/451348

Luscombe, K. & Oliva, F. A Short Basic Sciences Review of Articular Cartilage.

http://www.isakos.com/innovations/luscombe.html

Niall, D.M.& Bobic, V. ISAKOS Current Concepts. Bone Bruising and Bone Marrow Edema Syndromes: Incidental Radiological Findings or Harbingers of Future Joint Degeneration?

http://www.isakos.com/innovations/niall.aspx

Minas, T. Autologous chondrocyte implantation for chondral defects of the knee.

www.orthojournalhms.org/volume2/html/articles6.htm

Wroble, R.R. Articular Cartilage Injury and Autologous Chondrocyte Implantation Which Patients Might Benefit?

http://www.physsportsmed.com/issues/2000/11_00/wroble.htm

Tissue Engineering Companies

Ars Arthro - Patient Information

http://www.arsarthro.com/en/patient_schritt.php

Fidia Advanced Biopolymers

http://www.fidiapharma.it/files/index.cfm?id_rst=130

Geistlich Biomaterials - Patient information

http://www.geistlich.com/biomaterials/en/patients/index.html?frames/content.html

Genzyme Biosurgery - Carticel Patient Information

http://www.genzymebiosurgery.com/prod/cartilage/gzbx_p_pt_cartilage.asp

OBI OsteoBiologics - Patient Information

http://www.obi.com/patients_brochure.htm

Tigenix - Patient Website

http://www.tigenix.com/home.asp?map=h_chondro

Other Useful Sites

The Cartilage Research Foundation

http://www.cartilagefoundation.org/

Webcast of Carticel Articular Cartilage Repair

NB This webcast is not for the faint hearted as it shows video of the actual surgical procedure.

http://www.slp3d2.com/sfi_1012/broadcast.html

Cartilage Restoration Symposium Videos

NB These videos are not for the faint hearted as they show images of actual surgical procedures.

http://www.slp3d2.com/gen_1061/