Cartilage pathology

Focal chondral lesion

What is it ?

The cartilage is a firm tissue that cushions bones at joints, allowing a smooth motion between the femoral condyles and the tibial plateau, and between the patella and the trochlea. The cartilage is nourrished by the underlyling bone. When the cartilages wears and tears, arthritis develops (see chapter arthritis). But a healthy cartilage may be focally damaged by an accident: if the cartilage only is damaged it is a focal chondral lesion, and if the underlying bone has also been damaged it is an osteochondral fracture. An isolated focal chondral lesion may be due to a direct trauma, or may be due to a severe knee sprain (associated to ligaments tear) or to a patellar dislocation.

Clinical presentation

A focal chondral lesion is painful and often enhances a mechanical knee effusion (swelling after activity). If a cartilage fragment in unstable it may be felt as clics in the joints during the movement, and if the fragment is detached and loose in the joint it may cause sudden lockings.

When to consult a specialist?

A specialist should be consulted in case of persisting pain, knee swelling or lockings/clics after a knee trauma.

Non surgical treatment

A conservative treatment is indicated for a small, stable and focal chondral lesion: the goal is to reduce the pressure on the cartilage using crutches to walk for example. Cycling movements without any resistance, on a stationary bike or in a pool are recommended to enhance cartilage healing. Intra-articular injections of hyaluronic acid may lower the pain and intra-articular PRP injections (platelet-rich plasma) may help the cartilage healing by inducing a biological boost.

Surgical treatment

A surgical treatment is indicated if a chondral or osteochondral fragment is unstable or has been detached and is loose in the joint; surgery is also indicated in case of failure of a conservative treatment. Usually a diagnostic arthroscopy is performed first to see the chondral lesion, palpate it, and confirm its characteristics: location, size and deepness. These characteristics will tell us which is the best technique to use, either by arthroscopy or by arthrotomy (open surgery):

micro- or nano-fractures (perforations of the subchondral bone to enhance a bleeding which contains bone-marrow stems cells, which will help healing)
chondroplasty (curetage to enhance bleeding of the lesion)
chondral or osteochondral fixation of an unstable or loose fragment, using pins or screws
autologous osteochondral graft: the damaged cartilage is removed as a plug, including the underlying bone; another plug is harvested in another part of the knee and grafted where the lesion was; if many plugs are necessary it is called a mosaic-plasty.
autologous chondrocytes graft: some chondrocytes are harvested from the patient knee, cultured in a lab, associated to a matrix, and then grafted as a plug in the damaged part of the knee.
synthetic matrix: collagen scaffold used for a guided regeneration of the cartilage, in association to microfractures or chondroplasty.

Postoperative follow-up

The post-operative phase is crucial for a good cartilage healing and can influence the final results. During the first 6 weeks after surgery (healing phase) the patient walks with crutches and do cycling movements without resistance. Between 6 weeks and 3 months after surgery (transition phase), the patient walks progressively with full weigh bearing and muscular training begins with light resistance. After 3 months (remodelling phase), sports activities are progressively allowed. Return to impact sports will be 9 to 18 months after surgery.

Risks and complications

The most feared complication is a non-healing of the surgically treated chondral lesion. Known complications after any knee surgery as stiffness, infection, etc. are rare but exist.