Osteoarthritis is a well known disease affecting joints, mainly of the hip, knee and spine. Articular cartilage, the lining tissue at the ends of long bones is mainly affected. The underlying bones, joint capsule and synovial fluid also show changes. Pain, swelling, stiffness, catching are common symptoms. In Indians, knee osteoarthritis is very common and even younger people in their fourth decade have some earlier symptoms. In this article I shall discuss the precursor of the disease, “cartilage lesion” and surgical methods to prevent or treat early cartilage disease. By availing of these alternate methods of surgery the need for joint replacement can be averted or postponed by younger people. I shall confine myself to the knee joint but the same principles can apply to any other joint.
Articular cartilage is the shiny tissue that lines the ends of bones participating in a joint. It is the natural shock absorber. Loss of this tissue is responsible for the development of osteoarthritis. Healthy cartilage is a bluish white, smooth, glistening tissue. It has no blood and nerve supply. It is precious since there is a limit to its complete regeneration unlike tissues in other organs and even in the underlying bone.
Healing of articular cartilage vs other tissues
In most other organs healing takes place by bleeding and organization of the blood clot as you must have observed after suffering an injury to your skin. A scab forms in the blood clot. A bone when fractured can heal completely under normal circumstances and after a few years will not show any sign of fracture. This does not happen in cartilage under normal circumstances but can happen under controlled surgical procedures. Articular cartilage damage is permanent and will become worse with time, sometimes requiring surgery. Small areas of cartilage can be repaired by methods discussed here. Larger areas of cartilage loss may need a "biological" or metallic joint replacement. Biologic transplant is performed by implanting cartilage or menisci obtained from the joints of brain dead fresh cadavers or donors into damaged joints. Liberalization of laws governing cadaver tissue harvesting and availability of cold storage facilities will make this procedure popular.
The other more popular option is total joint replacement. With increased longevity and affluence more people are electing for joint replacement. The life of a total joint prosthesis is fifteen to twenty years and therefore total joint replacement is not advised in younger patients. If ever they do need one, they must understand that in future they may need a revision replacement.
Causative factors for articular cartilage damage
The initial and main factor leading to articular cartilage damage is increased mechanical stress. As discussed above normal cartilage is capable of limited repair in the young. When the capacity of repair is exceeded, articular cartilage damage results. In the knee joint, it can occur under the following circumstances.
a) After a sudden mechanical injury in sports or a vehicular accident. Damage to the menisci and ligaments are immediately recognized by clinical methods but cartilage damage goes unnoticed. It may occur over areas of bone bruising seen on MRI films.
b) Mal alignment of a joint - People with bow legs and knock knees are at risk of getting arthritis at an earlier age. Even people with small degrees of bow legs can develop knee pain as shown on loading experiments in cadaveric knees.
c) Obesity due to the excessive loads placed on the joints. The normal knee transmits up to three times the body weight during walking and this goes up to seven times in the knee cap joint.
d) Certain occupations like carpenters, plumbers, dock workers, mine workers, carpet layers, are likely to suffer from knee cartilage lesions because of the heavy load on the knee joints.
e) Excessive Immobilization of a joint or overuse as in heavy sports can lead to cartilage damage.
f) Aging- The erect posture of man’s knee extracts a price in the form of inner knee wear. Unable to withstand the stresses of a lifetime, steady cartilage loss occurs, leading to knee pain in the middle aged.
g) Thermal injury as after short wave diathermy administered by physiotherapists and orthopaedic surgeons as conservative treatment for knee pain.
Young patients with ligament and meniscal injuries can develop cartilage injuries. Any in middle aged person, more so obese individuals, can develop symptoms of early cartilage disease. Some patients with articular cartilage injury may not complain. When the weight bearing portion of the knee joint is affected, pain, catching sensation, swelling are the common symptoms. There is no sex differentiation. Pain progresses, however in the knee it is not disabling unlike the hip.
Normal x- rays may not show early cartilage lesions. Their presence can be inferred by the presence of osteophytes. Special x rays can show joint space narrowing. Arthroscopy or MRI can show the size, position and depth of the cartilage. MRI interpretation is operator dependent.
1) Regular exercise tones up muscles and joints. Well developed muscles can prevent joint injury after an accident and can lead to early recovery from an operation. In combination with a proper diet, exercise can lower body weight
2) Diet- Obese with knee pain can benefit from weight loss. Soya, low fat milk, fruits and vegetables, berries, fiber lead to weight loss. However over a long time, people tend to loose interest and weight lost tends to be regained. Thus diet cannot play an important role in the long run.
3) Alcohol abuse and fatty foods are to be avoided.
4) Nutritional supplements like Glucosamine comes to the rescue of younger patients.
They are available to treat early cartilage lesions. They can be done arthroscopically or by an open method. Drilling, abrasion, cartilage transfer from the unaffected part of the joint can be accomplished arthroscopically.
Cartilage Arthroscopic microfracture and Mosaicplasty are two techniques to repair localized small cartilage defects.
A new procedure is to be introduced in Chennai for young patients. This is called autologous cartilage cell transplant. Young & active patients with a post traumatic cartilage defect measuring about 2- 8cm will be the ideal candidates. Older patients with degenerative changes will do better with a joint replacement.
In this procedure, cartilage cells are obtained from the healthy part of a joint and sent to a laboratory. The cells are cultured in the lab wherein the cell count is multiplied several million times. These cells are returned to the surgeon. He re-implants these cells into the defect and closes the joint. The cells synthesize normal articular cartilage in the defective area. It is recommended for lesions.
Ligament and meniscal injuries should be treated to prevent early osteoarthritis. ACL reconstruction is recommended to prevent further damage to the menisci in people with a torn anterior cruciate ligament. Meniscal suture of torn menisci is possible if done early and the tear occurs in a vascularised (with a blood supply) of the meniscus.
Meniscal transplant is a new technique that can substitute the damaged menisci with cadaveric menisci. This procedure is to be to offered to young patients with an ACL injury and concomitant meniscal injury where the torn meniscus has been removed. This surgery will postpone the onset of osteoarthritis.
Osteotomy- If congenital or acquired bony mal-alignment is present then osteotomy can restore normal alignment. In osteotomy either a wedge of bone is removed from the convex side of a deformed leg or a wedge is created on the concave side of the bent leg. An osteotomy alters the line of abnormal load bearing thus preventing the progression of osteoarthritis.
A corrective osteotomy of the knee relieves pain in middle aged people. Evidence is mounting that an osteotomy is not only useful in relieving pain in the symptomatic person but also can prevent knee pain in those with deformities. People need to be convinced about this fact.
I offer these procedures to younger patients so that they can avoid joint replacement. To fully benefit from these procedures, the patients should be willing to participate in a rehabilitation program. These surgical options are alternatives to knee replacement for knee pain in younger patients. They will improve the quality of life and postpone or avoid a knee replacement.
The author is a consultant Orthopaedic surgeon in Chennai and provides knee surgery and replacement options for all age groups. Latest advances in knee replacement like computer assisted knee replacement, Oxinium knee, flexible knees are provided at a reasonable cost.
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