April 24, 2005
More than a simple
hingeBy Paul Yeo
Orthopaedic surgeon Dr Thirukumaran provides Fit For
LIfe information about knee pain and a solution to such pain for
certain patients – autologous chondrocyte implantation.
THE knee joint’s main function is to bend and straighten.
However, it can also twist and rotate to some degree. To do this,
the knee joint relies on different structures –bones, ligaments,
tendons and cartilage.
The knee joint involves three bones – the thighbone or femur, the
tibia (one of the bones in the lower leg; the other bone in the
calf, the fibula, is not involved in the joint) and the kneecap or
patella (along the front of the femur).
Ligaments are fibrous bands that connect bones to each other. The
knee has four important ligaments that connect the femur to the
tibia: the anterior cruciate ligament (ACL) and posterior cruciate
ligament (PCL). These provide front and back and rotational
stability to the knee.
The medial collateral
ligament (MCL) and lateral collateral ligament (LCL) provide medial
and lateral stability to the knee.
Comparing healthy and damaged cartilage in
a knee joint.
These ligaments are often affected when the knee is subjected to
movements beyond its normal range. Hence, sports professionals often
injure these ligaments, and serious injuries can often threaten the
career of such athletes.
Tendons are also fibrous bands, but unlike ligaments, these
connect bones to muscles. The important tendons in the knee are the
quadriceps tendon (connects the quadriceps muscle on the front of
the thigh to the patella) and the patellar tendon (connects the
patella to the tibia – technically this is a ligament because it
Cartilaginous structures called menisci lie within the end of the
bones that form a joint. These structures are crucial as they
provide both space and cushion for the knee joint.
When problems arise in the knee, the primary symptom is pain.
Take note that the nerves that provide sensation to the knee come
from the lower back and also provide hip, leg, and ankle sensation.
Hence, pain from a deeper injury (called referred pain) can be
passed along the nerve to be felt on the surface. Knee pain,
therefore, can arise from the knee itself or be referred from
conditions of the hip, ankle, or lower back.
In general, knee pain is either immediate (acute) or long-term
(chronic). Acute knee pains can be caused by an acute injury or
infection. Chronic knee pains are often from injuries or
inflammation (such as arthritis) but can also be caused by
In the elderly, the most common cause of knee pain is
osteoarthritis. Osteoarthritis is caused by degeneration of
cartilage in the knee. In its extreme form, the cartilage will be
completely eroded, and the femur will rub on the tibia (bone on
bone). When this occurs, it results in a chronically painful knee
that is often more painful with activity.
Simply put, cartilage is the shiny, smooth white tissue found at
the end of bones that form joints. It consists of a matrix of
connective tissue called chondrocytes, which are held in a matrix of
This cartilage, along with joint fluid, is responsible for the
smooth and pain-free movement of the knee joint.
Arthritis can be caused by wear and tear (osteoarthritis),
infection( septic arthritis) and autoimmune inflammation (rheumatoid
arthritis) among others.
Osteoarthritis or wear and
tear arthritis is the most common cause of arthritis and joint pain
in the elderly. This wear of articular cartilage especially occurs
in the weight bearing joints and the knee joint is the most common
In total knee reconstruction, all damaged
cartilage from the knee joint is removed and the articulating
surfaces of the knee are resurfaced with artificial surfaces
such as metal or
As this disease progresses the joint may also become deformed as
cartilage wear occurs and this can commonly result in bow legs as
seen in many people above 60.
Unfortunately articular cartilage is one of the body tissues with
a limited ability of regeneration. Thus once damaged or degenerated,
the area of damaged cartilage is usually permanent.
In the young, knee pain is generally caused by damage to the
ligaments, menisci or cartilage, chiefly as a result of trauma from
sports or road traffic accidents. Ligament injury, especially the
anterior cruciate ligament, is extremely common among
Twenty years ago, this injury would have ended careers. Now,
surgery is now so successful that the ligament can be reconstructed
in less than two hours with minimal pain or scars. Patients can
return to the same level of competitive sport and the list of
athletes who have successfully undergone such procedures are long
and include Alan Shearer, Ruud Van Nistelrooy, Roy Keane, Fredie
Lundjberg among others. Menicus injuries also can be successful
Articular cartilage injury in a young person, until recently,
posed a more difficult problem. As mentioned earlier, cartilage does
not regenerate and replacement with artificial surfaces are not an
option in the young and active. Knee pain from cartilage injury thus
used to be permanent.
Current available medication does not stimulate any repair or
regeneration of cartilage. No scientific evidence consistently show
that the popular joint supplements or joint foods sold over the
counter have any beneficial effect, contrary to popular
Fortunately, surgical options are available. In the elderly, a
total knee replacement is an excellent option. In this surgery, all
damaged cartilage from the knee joint is removed and the
articulating surfaces of the knee are resurfaced with artificial
surfaces such as metal or plastics. Total knee replacement is an
excellent treatment option as it renders the patient pain free and
can also correct stiffness and deformity.
However it is not ideal in the young and active as these
artificial materials have a limited accumulated load tolerance and
will eventually fail.
As with other areas in
medicine a more biological or natural solution looks to be the ideal
When the knee is injured, pain and swelling
ensues due to substances released by the body that cause
ACI or autologous chondrocyte implantation is one of the few
treatment options for this problem. Developed in Sweden in the late
1980s, it now beginning to gain acceptance worldwide.
In this procedure, healthy articular cartilage is “harvested”
from an uninjured area of the patient’s joint. Chondrocytes or
cartilage cells derived from this are then cultured and multiplied
in a laboratory. These are then re-implanted in the joint to replace
damaged areas of cartilage. These cells grow and replace the damaged
cartilage and clinical results have shown that the patient
experiences excellent relief of symptoms.
Used widely now in Europe and the US, the only drawback of this
technique is that an expensive, well-equipped laboratory with highly
specialised scientists are necessary for the culturing of the
chondrocytes. Surgeons also need to be well trained in the operative
worldwide joint declaration
Friendly | Email