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  • Joint Surface Problems

    Joint surface problems can be in the form of injuries, where there
    is damage to the articular chondral (cartilage) surface, or early
    degeneration.

    Osteochondral injury implies an injury to articular cartilage with
    some of the underlying bone. Chondral injury implies only the articular
    cartilage. Another condition affecting the joint surface,
    osteochondritis dissecans (OCD), is also included in this section.

    Background

    Background

    The articular cartilage may be damaged after a jarring or twisting injury of the knee. It may also occur in conjunction with meniscus and ligament injury. The result can be a loose fragment of articular cartilage which leaves an exposed area of bone in the knee (a crater in the otherwise smooth joint surface). Alternatively the damage may be a breaking up or splitting, but not complete loss of, the articular cartilage.
    In younger patients, this will usually result from a clear injury when there is a shearing or impaction force between the two surfaces. As we get older the articular cartilage becomes more degenerate and fragile, so injuries occur more easily (similarly for tears of the meniscus cartilage). In these cases there seems to be an overlap with the early beginnings of osteoarthritis.
    Joint surface injury can be a potentially troublesome condition, particularly in young adults, because it may give rise to long term problems. It has been known for many years that articular cartilage does not heal well. If the meniscus is also torn, the prognosis is worse. It can be difficult to treat, and can increase the risk of developing significant osteoarthritis.

    knee-joint-surface-problems-0001

    Symptoms

    Symptoms

    The symptoms of chondral injury are pain, clicking, catching and swelling. Sometimes locking may occur. The pain may be well localized to the area of damage. Occasionally, it is difficult to say exactly where the pain is arising from, and the knee feels generally uncomfortable.
    If the injury has resulted in a fragment of the joint surface cartilage floating around the knee there can also be symptoms of a loose body, with clunking, catching.

    Diagnosis

    Diagnosis

    The diagnosis of a chondral injury in the knee joint can be made on the story of an injury along with examination of the knee which may reveal nothing more than discomfort and swelling. A bigger injury, when a piece of cartilage and bone has come off, is called an osteochondral fracture, and will present with more severe pain and swelling due to bleeding into the knee. An example of this might be when a patella dislocation occurs.
    X-rays are useful if there is a small fragment of bone as well as a fragment of articular cartilage (i.e. osteochondral damage). If not, the x-rays will probably be normal.
    An MRI scan will show up most chondral injuries, but can miss smaller ones. If there is a suspicion of such an injury but x-rays and MRI scan are negative, arthroscopic surgery may be required both for diagnosis and treatment.

    Treatment

    Treatment

    Treatment of the injury depends on the size, site and depth of the damaged area. Small areas of chondral damage in older patients are not uncommon, and can settle over 6-8 weeks with rest and anti-inflammatory tablets. However, background problems of aching and swelling might persist.
    Many acute chondral injuries need to be treated with arthroscopic surgery to either remove or repair the damaged fragment.
    In general the only repairable injuries are where there is quite a large chunk of articular cartilage, preferably with a sliver of bone attached (an osteochondral fracture) which can be pinned back in place. There is a good chance of healing in this instance.
    In cases where the fragment has to be removed, or where the patients comes long after the injury, you can be faced with pain due to loss of normal articular cartilage covering.
    There may be a crater in an important part of the knee with bare bone in the base. It will not heal up with normal joint surface cartilage. It may heal up with fibrocartilage or scar tissue in the base giving some sort of smooth covering. Even if this does happen, there can still be problems, in which case surgery could be needed.

    Microfracture

    “Microfracture” is the making some small holes in the bone with a sharp pick or small drill. By encouraging bleeding from the bone in the damaged area, a fibrocartilage covering forms. It is thought the blood contains bone marrow stem cells which can help healing. This is not as good as the original articular cartilage but is very effective.

    Microfracture is a very useful and simple technique, and can be done as day case keyhole surgery. Depending on the size and site of the microfracture area, crutches might be needed for up to six weeks.

    Knee Joint Surface Problems

    Osteochondral autograft transplantation surgery (OATS)

    OATS, also called mosaicplasty, is a technique where we some healthy plugs (cylinders) of bone and articular cartilage from one area of the knee (where it is required less) and put them into the damaged area.

    OATS has a role in the treatment of some defects, especially they are deep with bone loss, but generally only in small areas of damage.

    Artificial plugs to fill similar areas have been used, but results have been disappointing and research is on-going in this area.

    Knee Joint Surface Problems

    ACI (Autologous chondrocyte implantation)

    ACI (Autologous chondrocyte implantation) involves the culture of chondral (articular cartilage) cells removed from your knee, which are then, at a second operation, re-implanted into the defect. Although this sounds like an ideal technique, and has been performed for a number of years, the results have been largely disappointing compared to the high expectations. In many cases biopsies taken after surgery have shown that any new covering is simply scar tissue which has formed in the crater, rather than the desired articular cartilage. Despite the optimism, it is no better than microfracture, requires two operations, and is very expensive.

    The reason may be that the cultured cells themselves are simply not healthy enough to create adequate normal joint surface tissue.

    Knee Joint Surface Problems

    What next in joint surface injury?

    There is an enormous amount of research going on into treating the damaged joint surface. There is currently no perfect treatment for joint surface injuries, or degenerate damage, and with current technology it is not possible to reliably re-create the normal articular surface.

    Stem cells are unspecialised (undifferentiated) cells, which can develop into other cells or tissues. MSCs (mesenchymal stem cells) are stem cells which eventually form cartilage. Much effort is being put into this area, and might be something for the future.

    Yorkshire Knee Clinic Surgeons are actively involved in this research.

    Osteochondritis Dissecans (OCD)

    Osteochondritis Dissecans (OCD)

    OCD is a condition that affects the knee, as well as other joints. A small piece of bone separates from the joint surface and causes symptoms of pain and swelling. Sometimes the piece can fall out into the knee, in which case symptoms may be of sharp pains and locking or trapping.

    It tends to occur between 10-15 yrs age, when it is called Juvenile OCD, but can occur at any age. It is a little more common in boys. The exact cause is not known, but may be related to doing a lot of sport. A temporary interruption to the blood supply to a section of the bone may be responsible. In cases there may be some inherited factors.

    The most usual place for OCD in the knee is on the medial femoral condyle. This is so-called “classical site” OCD.

    Investigations
    Investigations will usually consist of an x-ray, which can be normal early on in the disease, and an MRI scan which is more sensitive and accurate. An MRI scan will show the condition long before it is visible on x-ray, and for that reason is extremely useful.

    OCD

    Knee Joint Surface Problems

    Treatment

    The treatment of juvenile OCD will initially consist of reducing activity and sport, especially those involving repetitive impact, twisting and jumping.

    If the OCD fails to heal (on monitoring symptoms, x-rays and MRI scans), surgery is sometimes required. This might entail keyhole surgery with drilling of the loose fragment to encourage it to heal. Sometimes, depending on a number of factors, the piece is fixed back with pins or small screws. If it develops into a loose body in the knee, the loose piece has to be removed.

    The long term effects of having OCD of the knee are variable. Depending on age of onset, size of the OCD, and compliance with treatment, it may be something which can result in a fairly normal knee, or can cause more disabling problems in the long term. Unfortunately it is often difficult to predict which way any particular case will go.