The term arthritis literally means inflammation of a joint, but is generally used to describe any condition in which there is damage to the cartilage. Damage of the cartilage in the knee joint causes knee arthritis. Inflammation is the body’s natural response to injury. The warning signs that inflammation presents are redness, swelling, heat and pain.
The cartilage is a padding that absorbs stress. The proportion of cartilage damage and synovial inflammation varies with the type and stage of arthritis. Usually, the pain early on is due to inflammation. In the later stages, when the cartilage is worn away, most of the pain comes from the mechanical friction of raw bones rubbing on each other.
Types of Arthritis
There are over 100 different types of rheumatic diseases. The most common causes of arthritis are osteoarthritis and rheumatoid arthritis.
Osteoarthritis: Osteoarthritis is also called degenerative joint disease. This is the most common type of arthritis, which occurs often in older people. This disease affects cartilage, the tissue that cushions and protects the ends of bones in a joint. With osteoarthritis, the cartilage starts to wear away over time. In extreme cases, the cartilage can completely wear away, leaving nothing to protect the bones in a joint, causing bone-on-bone contact. Bones may also bulge, or stick out at the end of a joint, and this is called a bone spur.
Osteoarthritis causes joint pain and can limit a person’s normal range of motion (the ability to freely move and bend a joint). When severe, the knee joint may lose all movement, making a person very disabled.
Rheumatoid Arthritis: This is an auto-immune disease in which the body’s immune system (the body’s way of fighting infection) attacks healthy joints, tissues, and organs. Occurring most often in women of childbearing age (15-50), this disease inflames the lining (or synovium) of joints. It can cause pain, stiffness, swelling, and loss of function in joints. When severe, rheumatoid arthritis can deform, or change, a joint.
Rheumatoid arthritis affects mostly joints of the hands and feet and tends to be symmetrical. This means the disease affects the same joints on both sides of the body (both the hands or both feet) at the same time and with the same symptoms. About two to three times as many women as men have this disease
Post traumatic arthritis: Any injury to the knee that may or may not be associated with a fracture or dislocation can predispose the shoulder to subsequent arthritis. The risk is highest with a fracture involving the articulating surfaces of the thigh and leg bones of the knee joint. In some fractures of the upper end of the leg bone that are fractured into many pieces the blood supply to this portion of the bone may be affected leading to bone cell death. This condition is called Avascular necrosis and can be a cause of rapidly progressive post traumatic knee arthritis.
Instability Arthritis: A tear of one or more of the ligaments of knee joint or of the rim of tissue (meniscus) following repeated knee dislocations or failed or delayed surgery for knee instability, can lead to a mechanical imbalance of the forces around the knee. This can lead to eccentric loading and early wear and tear of the knee joint. This type of arthritis typically involves the inside of the knee (medial compartment osteoarthritis).
Causes
Osteoarthritis is caused by the wearing out of the cartilage covering the bone ends in a joint. This may be due to excessive strain over prolonged periods of time, or due to other joint diseases, injury or deformity. Primary osteoarthritis is commonly associated with ageing and general degeneration of joints.
Secondary osteoarthritis is generally the consequence of another disease or condition, such as repeated trauma or surgery to the affected joint, or abnormal joint structures from the time of birth.
Rheumatoid arthritis is often caused when the genes responsible for the disease are triggered by infection or environmental factors. With this trigger the body produces antibodies, the defence mechanism of the body, against the joint and may cause rheumatoid arthritis.
Symptoms
There are several forms of arthritis and the symptoms vary according to the form of arthritis. Each form affects the body differently. Arthritic symptoms generally include swelling and pain or tenderness in joints for more than two weeks, redness or heat in a joint, limitation of motion of a joint, and early morning joint stiffness.
In an arthritic knee
- The cartilage lining is thinner than normal or completely absent. The degree of cartilage damage and inflammation varies with the type and stage of arthritis
- The capsule of the arthritic knee is swollen
- The joint space is narrowed and irregular in outline; this can be seen in an X-ray image.
- Bone spurs or excessive bone can also build up around the edges of the joint
Diagnosis
Dr Bala will diagnose arthritis with a medical history, physical exam and X-rays of the affected part. It is important to get standing/weight bearing Xrays of both knees to compare the arthritis in 1 knee to the other. Xrays taken lying down are or limited value. Infact Xrays of both the lower limbs in entirety standing called scannograms are taken to assess the weight bearing axis of both lower limbs before surgery.
Computed tomography (CT) scans and magnetic resonance imaging (MRI) scans are also performed to diagnose arthritis. MRI scans have limited value in advanced arthritis.
Treatment Options
Dr Bala may prescribe anti-inflammatory medicine. He may recommend physiotherapy, which includes exercises and heat treatment. In some cases, an injection into the joint can help. There are different types of injections. The simplest and cheapest of the injections are the steroid injections. Steroid injections are safe if you aren’t a diabetic or have well controlled diabetes. Upto 2 steroid injections maybe given before opting for surgery. The second type of injection is the lubricant (Hyaluronic Acid). This is also effective in early arthritis. More recently biologic injections are another option. Blood from one’s body is spun in a centrifuge machine and the cells with growth potential are concentrated and/or activated before injecting into the knee joint. This injection is called PRP (Platelet Rich Plasma) or ACRS (Autologous Cytokine Rich Serum). The efficacy of these injections is still under investigation.
In severe cases surgery may be suggested. The type of surgery will depend on your age and severity of the disease. In the elderly with severe arthritis, joint replacement usually gives good results. This is usually an excision of the damaged joint surface, and implantation of a partial replacement (unicompartmental arthroplasty medial compartment, unicompartmental replacement lateral compartment, patellofemoral replacement) or total knee replacement depending on which all portions of the knee are worn out, the age and physical demand of the patient, weight and the MRI findings.
In cases of severe arthritis where there is bone loss on the inside of the leg bone special techniques are needed for knee replacement. These include the use of stems, augments, 3D printing of the knee using a special CT scan or robotic knee replacement to help design guides to help in the accurate placement of the knee replacement. Dr Bala is trained in the use of such Patient Specific Instrumentation (PSI).
In other cases of severe arthritis, the CT scan is used to design a custom-made prosthesis for knee replacement).
Dr Bala has been part of teams designing instrumentation for the use of computers in joint replacement surgery (navigated joint replacement) and his publication was presented at the Annual meeting of American Academy of Orthopaedic Surgeons (AAOS) in 2016. Dr Bala was part of one of the first few robotic joint replacements in the Asia pacific region in 2015.
Some of Dr Bala’s interests lie in complex knee replacements for tumours, fractures around knee replacements and revision knee replacements.
Dr Bala has also designed a novel technique to mould a cement spacer during surgery when treating infected joint replacements.
In rare cases where the knee arthritis fails due to an infection the only option for a painless knee is knee fusion (knee arthrodesis). This can be achieved with 2 perpendicular plates or a ring construct (Ilizarov frame) and bone graft taken from the waist.