Articular cartilage, also called hyaline cartilage, is the smooth, glistening white tissue that covers the surface of all the diarthrodial joints in the human body. As its name implies, articular cartilage is critical in the movement of one bone against another. Articular cartilage has an incredibly low coefficient of friction which, coupled with its ability to bear very large compressive loads, makes it ideally suited for placement in joints, such as the knee and hip.

Cartilage is composed of specialized cells called chondrocytes that produce a large amount of extracellular matrix composed of Type II collagen (except Fibrocartilage which also contains type I collagen) fibers, abundant ground substance rich in proteoglycan, and elastin fibers. Cartilage is classified in three types, elastic cartilage, hyaline cartilage and fibrocartilage, which differ in the relative amounts of these three main components.

Unlike other connective tissues, cartilage does not contain blood vessels. The chondrocytes are supplied by diffusion, helped by the pumping action generated by compression of the articular cartilage or flexion of the elastic cartilage. Thus, compared to other connective tissues, cartilage grows and repairs more slowly.


Articular cartilage lesions in people and athletic population commonly occur and result from the significant acute and chronic joint stress associated with high impact activities. These lesions have poor intrinsic healing capacity, and the persistent defect in the joint surfaces cause pain, swelling and mechanical symptoms that result in functional impairment and limitation of athletic participation. If untreated, articular cartilage lesions can lead to chronic joint degeneration and disability. Several techniques for articular cartilage repair have been recently developed with promising results.


• Patients with focal chondral defects generally have symptoms localized to the lesion location.
• Symptoms that worsen with weight-bearing activities likely are produced by damage that resides in the femoral condyle.
• Pain when arising from a sitting position following prolonged knee flexion and with stair climbing suggests a lesion in the patellofemoral joint.
• Patients may complain of activity-related swelling.

An effusion may be palpable, and the affected joint may feel warmer in the presence of an underlying inflammatory process. The ranges of active and passive motion of the knee without effusion are usually within normal limits in the early stages of articular cartilage disease. Localized joint-line pain may be present on palpation, and the McMurray test may elicit some discomfort in the involved compartment. Associated degenerative meniscal tears and articular cartilage disease are commonly associated with older patients. The knee is usually stable to ligament evaluation in most patients, but excluding underlying ligamentous instability is an important part of the examination and future management.


Radiographic imaging of knees with chondral disease should include weight-bearing views for better estimation of mechanical and anatomical axis of lower limb.


Χ-ray knee joint.  Articular cartilage focal damage.

Magnetic resonance imaging (MRI) is a useful noninvasive means that may help demonstrate symptomatic articular cartilage lesions. There is often a high correlation with radiographs, but MRI may be particularly helpful when standard radiographs appear normal. Current techniques are more accurate in detecting partial or full-thickness cartilage loss and how large is the damage. These information can define the kind of operative technique which is the right for the patient.

Magnetic Resonance Imagine.  Chondral damage in trochlear groove (knee).

Magnetic Resonance Imaging, focal damage of articular cartilage (knee)

ESSKA Congress, Geneva, Swiss. Poster Presentation.



Treatment with autologous adult stem cells represents a promising new perspective on the rapidly evolving field of regenerative medicine and is currently the best alternative method for tissue regeneration. The stem cells are precursors of all cells of the human body and under suitable conditions can be converted into chondrocytes repairing thereby deficits of articular cartilage from the joint injury or due to a osteochondritis dissecans.


Conservative Treatment

Patients with acute chondral injuries are treated as soon as practical after the diagnosis is made, especially if the knee is being treated concurrently for meniscus or anterior cruciate ligament (ACL) pathology.

Patients with chronic or degenerative chondral lesions often are treated nonoperatively (conservatively) for at least 12 weeks after a suspected chondral lesion is diagnosed clinically. This treatment regimen includes activity modification, physical therapy, nonsteroidal anti-inflammatory drugs, viscosupplement injections, and perhaps dietary supplements that may have cartilage-stimulating properties. If nonoperative treatment is not successful, then surgical treatment is considered.



Many new techniques for the treatment of articular cartilage damage exist with very good results.



Microfracture technique in Osteochondritis Dissecans

Microfracture techniques combine with collagen substitute

Microfracture is indicated as first-line treatment for focal Outerbridge grade III and IV lesions under 3–4 cm2 in an otherwise nonarthritic knee in a symptomatic, active, and relatively young patient willing to respect the postoperative rehabilitation requirements.

For older and low-demand patients, microfracture may be useful even in lesions larger than 3–4 cm2.

Special instrument to create microfracture.

The microfracture is already done.

The blood contain special substance for remake the new cartilage.



Osteochondral autograft transplantation is a well-established technique in the treatment of chondral and osteochondral defect. Cylindrical osteochondral plug are harvested from areas of the articular surface with a lesser weight – bearing role and transferred to areas of osteochondral damage.

Using a press fit- technique, the plugs are inserted to replace damage or missing articular cartilage and to supply the chondral lesion with island of viable and immediately functional hyaline cartilage.

The presence of focal unipolar cartilage defects in the knee measuring 1-4 is a current indication for osteochondral autograft transplantation.


Donor site upper left, osteochondral press-fit right.  (Operative technique Sports Knee Surgery, Saunders Publication)

The plugs are inserted to replace damage articular cartilage.

Osteochondral imlantation. (3 cylinders).  (Μaster Techniques in Orthopeaedic Surgery.  Knee reconstruction 3rd edition).

Intraoperative view.


The procedure is not indicated for the condition as:

Generalized arthritis, rheumatoid and/or degenerative type
Lack of appropriate donor area
Infectious or tumor defects
Age greater than 50 years
Osteochondral defects deeper than 10 mm



Osteochondral allografts have been successfully used for the treatment of large and deep chondral and osteochondral lesion from acute trauma, osteochondritis dissecans and osteonecrosis.

Better outcomes have been reported in patients with unipolar lesions, without malalignment, rigid fixation and age younger than 50 years. Better outcomes are typically seen in young, active adults as well.
Lesion diameter typically ranges from 15 to 35 mm.

Controversies exist in cases:
• Patients with inflammatory arthritis
• Morbid obesity
• Medical problems that may interfere with the incorporation of the allograft into the host tissue

 Allograft plug is marked and ready for removal from condyle.

Different cannulated sizers are placed over the lesion to estimate the appropriate allograft diameter.

Allograft plug is trimmed carefully to the appropriate thickness.

The graft is gently press-fit into the socket.
(Operative techniques, Sports Knee Surgery, Saunders Publications)

The graft is seated and rotation, step-off, and stability are checked. 

ΜRI.  The graft is seated.


Injuries to joint surfaces can result from acute high-impact or repetitive shear and torsional loads to the superficial zone of the articular cartilage architecture. The use of autologous chondrocyte implantation is promising and is associated with several potential long-term benefit.

Autologous chondrocyte implantation is ideally suited for symptomatic deep chondral lesion along the femoral condyle or trochlear region. High-demand patient between 15-55 years of age with excellent motivation and potential for compliance are the best candidates.

However autologous chondrocyte implantation is a viable option for a symptomatic patient with a lesion of >2 but <12 and for a patient who continues to have pain after mosaicplasty or microfracture procedure.

Bone involvement is not contraindication, but staged or concomitant autologous bone grafting should be undertaken when the bone involvement is deeper than 6-8 mm.

Autologous chondrocyte transplantation is not a treatment for osteoarthritis (general joint disease), gout, and rheumatoid arthritis or other systemic joint diseases.

Femoral condyle chondral lesion.  Arthroscopic evaluation.

Chondral lesion mesuring during arthroscopy.

Autologous chondrocyte are arthroscopicaly harvested from a less weight-bearing area, commercially extracted from the harvested cartilage (200-500mg), and multiplied in vitro (labor cell culture).

Elective reinplantation is performed 4-6 weeks after cartilage harnesting by debridement of the defect to an intact margin, carelully avoiding osseous bleeding from the bed of the defect.

Clear the lesion area with curette.

The lesion area is already clear and ready to receveive the autologous chondrocyte.

Chondrocyte culture.

The surgeon cut the chondrocyte film like the shape of the chondral defect.

The autologous chondrocyte is ready to implant.

The autologous chondrocyte is transplanted.  The chondral defect is covered.

Chondral defect due to trauma.

The autologous chondlal cell filling the defect. 

The chondral defect covered by autologous chondrocyte atrhoscopically.

The procedure is finished.  The knee movement is without any problem.


Chondral lesion of femoral condyle before and after implantation.



Cold therapy is typically used for 1 to 7 days postoperatively.

Crutch-assisted touchdown weight-bearing ambulation (10% of body weight initially) is prescribed for 6 to 8 weeks, depending on the size of the lesion.

For most patients, 6 to 8 weeks is adequate time to limit weight bearing. However, for patients with small lesions (<1 cm diameter), weight bearing may be initiated earlier.

Patients with lesions on the femoral condyles or tibial plateaus rarely use a brace during the initial postoperative period. However, we may prescribe an unloading type brace when the patient becomes more active and the postoperative swelling has resolved.



Postoperatively, patients are placed in a hinged knee brace set at 0º to 90º. Therapy is initiated the next day and stresses range of motion exercises and isometric quadriceps strengthening.

An emphasis is placed on regaining range of motion and reducing postoperative effusion. The brace is unlocked after 1 weeks and is discontinued when the patient is able to perform a straight leg raise without an extension lag.

Patients are permitted only touch-down weight bearing for the first 6 weeks. At 6 week postoperative evaluation, the patient progresses to weight bearing as tolerated. The brace is discontinued.

After 12th week advanced strengthening with minimal restriction. Return to vigorous activities is discouraged for at least 12 months.


The early postoperative management include the use of continuous passive motion while the patient is in the hospital.

Patient generally are allowed a full range of motion unless they had undergone additional reconstructive procedures such a meniscal repair, anterior cruciate ligament reconstruction or osteotomy that would alter the rehabilitation plan.

Patients are allowed touch-down weight bearing for a minimum of 6 to 8 weeks postoperatively, or until bony union is determined by radiographs.

For femoral condyle allografts, no bracing is needed; but if an osteotomy is performed, a hinged range-of-motion brace is used for protection until healing is apparent. Weight bearing is progressed slowly between the second and fourth month, with full weight bearing using a cane or crutch.


Postoperatively protected weight-bearing are restricted for 6 weeks. The crutches is necessary for walking.
The physical therapy program started 2nd post-op day with passive movement (physical therapist or CPM machine) until 4th week.

Therapy concentrates on quadriceps activation and isometric straight leg raises. After the 6th week the patient can walk without aid devices with full weight-bearing. Full weight bearing and full range of motion are achieved. Closed-chain exercises and functional training are started.

After 12th week Strengthening and functional training are progressed. Return to full activities is delayed for at least 8 months to protect the lesion as it matures.

Return to participation in pivoting sports is usually allowed by 12 months.