Pathology :

Osteoarthritis is a degenerative condition primarily affecting the articular cartilage. The first change observed is increased water content and depletion of the proteoglycans from the cartilage matrix. Repeated weight bearing on such cartilage leads to its fibrillation. The cartilage gets abraded by the grinding mechanism at work at the points of contact between the opposing articular surfaces until the underlying bone is exposed. With further ‘rubbing’ the subchondral bone becomes hard and glossy ( eburnated ). Meanwhile, the bone at the margins of the joint hypertrophies to form a rim of projecting spurs known as osteophytes.

A similar mechanism results in the formation of subchondral cysts and sclerosis. The loose flakes of the cartilage incite synovial inflammation and thickening of the capsule, leading to deformity and stiffness of the joint. Often one compartment of a joint is affected more than the other. For example, in the knee joint, the medial compartment is more prone to get the disease than the lateral, leading to a varus deformity (Genu varum).

Clinical features :

Mostly, this disease involves the joints of the lower limb. And also, commonly elderly people are more prone to this disease. Pain is the earliest symptom of the disease. It occurs intermittently initially and becomes constant over the months or years. Initially, it begins as a dull aching pain and comes after starting an activity after a period of rest; but later it becomes worse and cramp-like, and comes after the activity.

Coarse crepitus may also be a complaint of patients suffering from this disease. Swelling of the joint is also a complaint but usually arises later. This feature is mainly due to effusion of the joint due to inflammation of the synovial tissues. Stiffness is initially due to pain and muscle spasms, but later capsular contracture or incongruity of the joint surface contributes to it. Other symptoms are – a feeling of ‘instability’ of the joint, and ‘locking’ resulting from loose bodies and frayed menisci.

Examination :

On examination, the following features may be present. Tenderness on the joint line, Crepitus on the moving joint, Irregular and enlarged-looking joint due to the formation of peripheral osteophytes, Deformity – Varus of the knee, flexion – adduction – external rotation of the hip, effusion – is rare and transient, Terminal limitation of the movement, Subluxation detected on ligament testing and finally wasting of quadriceps femoris muscle.

Investigations :

Radiological examination: The diagnosis of osteoarthritis is mainly by Radiological means. The following are the some of the radiological features: Narrowing of the joint space, often limited to a part of the joint, eg., may be limited to the medial compartment of the tibiofemoral joint of the knee. Subchondral sclerosis – dense bone under the articular surface. Subchondral cysts, Osteophyte formation, Loose bodies and also Deformities of the joint. Other investigations include serological tests and ESR to rule out rheumatoid arthritis, Serum uric acid to rule out gout, and Arthroscopy (in case of loose or frayed meniscus ).

Treatment :

Principles of treatment : Once the disease starts, it progresses gradually, and there is no way to stop it. Hence efforts are directed, wherever possible, to the following : To delay the occurrence or stall the progress of the disease, if the disease has not begun yet. This is done by keeping the weight in check, doing regular fitness exercises, and having a lifestyle favourable to the affected part. To rehabilitate the patient, with or without surgery, if his disabilities can be partially or completely alleviated.

Drugs – Analgesics, chondroprotective agents like glucosamine, Chondroitin sulphate and Collagen peptide. their role as disease-modifying agents has yet not been established, but these could be tried in some early cases. Viscosupplementation like Sodium Hyaluronan, Supportive therapy like advising the patients to reduce weight, avoidance of stress and strain to the affected joint, local heat provides relief of pain and stiffness, exercises for building up the muscles controlling the joint help in providing stability to the joint, The local application of counter – irritants and liniments sometimes provide dramatic relief and also surgical treatment in selected cases.

Joint preservation Surgery :

In this type of surgery, the arthroscopic procedures involves arthroscopic removal of loose bodies and degenerated meniscal tears. And in arthroscopic chondroplasty, the degenerated, fibrillated cartilage is excised using a power driven shaver under arthroscopic vision. Results are unpredictable. Osteotomy near a joint brings about relief in symptoms, especially in arthritic joints with deformities. A high tibial osteotomy for OA of the knee with genu varum, and intertrochanteric osteotomy for OA of the hip also remains useful for pain relief.

Joint replacement : For cases crippled with advanced damage to the joint, total joint replacement operation has provided remarkable rehabilitation. These are now commonly performed for hip and knee. An artificial joint serves for about 10 – 15 years.