The knee joint is a hinge type of joint that connects the thigh bone, the femur, to the shin bone, the tibia. It is a major weight-bearing joint that is lined with cartilage on all three surfaces, the femur, the patella (kneecap), and the tibia. Cartilage forms a cushion for the ends of the bone to glide upon easily within the knee joint to provide painfree motion. Furthermore, the healthy knee is held together by strong ligaments and muscles that allow a person to walk.
Arthritis is a condition that most commonly affects the weight bearing joints of the body, i.e. hip, knee, and ankle. Arthritis simply means joint inflammation that can cause swelling, pain and destruction of cartilage surfaces within a joint. Cartilage acts as a cushion that lines the inside of the knee joint. Arthritis can result in a progressive wearing of the cartilage surfaces of the joint, which exposes the underlying bone and causes pain. When arthritis progresses to the point of exposing bone both surfaces of the joint, significant pain and disability can occur that is not well controlled with conservative treatment.
Arthritis of the knee can cause symptoms that include pain in the knee, thigh, and shin. Other symptoms can include restricted motion of the knee, swelling, limping, deformity, and shortening of the leg. Knee arthritis can cause worsening of back, hip, and leg problems because of abnormal walking and the increased stress on those areas.
Osteoarthritis or Degenerative Arthritis is the most common form of arthritis. It is most common in the weight-bearing joints, such as the hip, knee, and shoulder. Osteoarthritis causes a breakdown of the cartilage within the joint secondary to wear and tear. The cartilage surfaces within the joint simply wear out as a person gets older and can be accelerated with an injury or obesity. As cartilage wears away bone surfaces are exposed causing increased pain and disability. Osteoarthritis can occur in families and patients can have a genetic predisposition for developing arthritis.
Rheumatoid Arthritis is the most common form of inflammatory arthritis affecting 3% of women and 1% of men. Rheumatoid arthritis has strongly been linked to a hereditary cause, however, infectious causes have also been suggested. The symptoms of inflammatory arthritis are caused by the body’s own release of destructive enzymes and substances that cause resorption of cartilage and joint surfaces causing joint swelling, pain, and deformity. Rheumatoid arthritis can affect every joint within the body including the hands and feet; however, the weight-bearing joints are most affected.
Traumatic Injury to the hip can cause an injury to the cartilage surfaces of the knee resulting in an increased risk of developing arthritis. A fracture of the bones around the hip joint can also make a patient more prone to developing arthritis within that joint, even if the break is fixed surgically. Traumatic dislocation of the knee can occur with a major injury, such as a car accident or fall from a height. With a knee dislocation, the hinge joint of the knee becomes separated and can result in major ligament damage requiring ligament reconstruction with surgery.
Avascular Necrosis (AVN) or Osteonecrosis represents a loss of blood supply to bone adjacent to a joint surface that results in death of the underlying bone tissue. This segment of bone subsequently becomes soft and collapses as the body resorbs the injured tissue, which results in increasing pain and disability. The hip joint is the most common joint affected, however, it can also occur in the knee. AVN has many causes and has been associated with excessive alcohol use, steroid use, or trauma, sickle cell disease, and radiation therapy. X-ray and MRI are both helpful diagnostic tests to determine how advanced AVN can be.
Other Causes of Knee Arthritis include gout, systemic lupus erythematosus (SLE), psoriasis, ulcerative colitis, crohn´s disease, previous joint infection, and pseudogout, to name a few.
An experienced physician diagnoses arthritis of the hip with a careful physical examination. X-rays are commonly needed to confirm a physician’s diagnosis and to determine how significant the arthritis is so that an appropriate treatment can be recommended.
Treatment for arthritis of the knee fall into two categories: Conservative Options and Surgical Options. In general, Conservative Options need to be exhausted before any surgical intervention is recommended. Conservative treatment options include an exercise program, anti-inflammatory medications, and modification of activities at home and work. Anti-inflammatory medications include both pills by mouth and cortisone injections. Injectable viscous hyaluronic acid gels (Synvisc, Hyalgan) can also be helpful in patients with knee arthritis. Other helpful conservative options include a weight loss program for patients that might be overweight and walking aids, such as a cane. Conservative treatment options seek to decrease the rate of arthritis progression and alleviate symptoms.
Surgical options for arthritis of the knee primarily include arthroscopy, osteotomy, and joint replacement. Knee arthroscopy allows a surgeon to utilize a small tube and light to look within the knee joint through very small incisions in the skin. Arthroscopy is most beneficial in the early stages of arthritis to remove loose bone or cartilage fragments, in addition to meniscal tears, that act as mechanical restraints within the knee joint. Arthroscopy generally does not cure the problem, but can substantially improve pain and function without undergoing a major operation. An osteotomy of the knee allows the surgeon to realign and straighten the bone by making a cut in the bone. This realignment procedure can preserve function without utilization of a prosthesis and decrease the rate of arthritis progression. Joint replacement is the most effective option to cure arthritis and involves utilizing prosthesis made of metal and plastic to replace the knee joint. Joint replacement is most appropriate when all other treatment options have failed and a patient continues to be symptomatic from advanced arthritis.
All surgical treatment options are technically complicated procedures and are best performed by an orthopaedic surgeon specially trained in treatment of knee arthritis.