Degenerative joint disorders- osteoarthritis
Osteoarthritis is by far the most common condition affecting synovial joints and is associated with significant morbidity and health service utilization. A precise definition of osteoarthritis however remains elusive. Pathologically, it represents focal cartilage loss in synovial joints with associated bony destruction manifesting radiologically as joint space narrowing, sclerosis of subchondral bone and osteophyte formation. Both primary and secondary forms of the disease are recognized.
Osteoarthritis is a part of a metabolically active, physiological response of degeneration and subsequent repair and may be reversible. Uncoupling of this equilibrium leads to inexorable joint damage.
Osteoarthritis is identified in all races and geographical locations, and the incidence increases progressively with age. Symptomatic osteoarthritis of the knee affects up to 15% of people over 55 years of age, but in many cases it is clinically silent (radiological evidence of osteoarthritis is found in more than 70% of those over 65 years).
Symptomatic osteoarthritis and severe radiographic changes seen in the hand and knee are more common in females. Caucasians are more frequently affected than blacks or Asians, which may reflect a genetic predisposition rather than a cultural difference.
The pathogenesis of osteoarthritis is multifactorial and primary osteoarthritis is said to be present when an underlying cause is unidentifiable. Secondary osteoarthritis occurs when an associated condition predisposes to degenerative change. Individual risk factors are divided into those that are generalized and/or localized. Generalized factors include genetic predisposition, gender, age and obesity. Localized factors include those which result in abnormal mechanical loading on a joint such as meniscectomy, instability and bony dysplasia.
Causes of secondary osteoarthritis
Congenital dislocation of the hip
Factors which have been implicated in the aetiology include failure of bone and cartilage remodelling, inflammation with enzymatic destruction of cartilage, ageing, abnormal joint loading, deposits of calcium apatite and calcium pyrophosphate, and abnormalities of neuromuscular function around a joint.
Genetic factors are important; a family history is present in 20% of patients with primary generalized disease. Genetic defects in type II collagen have been described in a rare familial form of osteoarthritis, and there is some evidence of an association with HLA factors.
At the molecular level, early disease leads to increased proteoglycan turnover and alteration in proteoglycan composition with an increase in type II collagen production. Histologically, the cartilage shows thinning, fibrillation, cleft formation, erosion and eventual loss of joint surface congruity.
Scope of disease
The predominant complication of osteoarthritis is progressive joint destruction. Lower limb osteoarthritis may lead to reduced mobility, and osteoarthritis of the hand may result in difficulty with manual tasks. This can be especially disabling in younger individuals who rely on normal joint function for employment.
Joint pain is the predominant symptom, being exacerbated by activity and relieved with rest. The commonly affected joints are the knees, hips, first carpo-metacarpal, distal and proximal interphalangealand cervical and lumbar spine apophysial (facet) joints. Other symptoms include swelling, stiffness, reduced function and joint deformity.
On examination, crepitus, instability, muscle weakness or wasting and occasionally synovitis may be evident. Knee and hip osteoarthritis may lead to limitation of mobility. It is noteworthy that there may be significant discordance between symptoms and signs. In addition, pain (a subjective experience) and functional impairment may be greatly affected by personality, anxiety, affect and daily activity.
Certain subtypes of osteoarthritis have been described, however the distinctions are arbitrary. Nodal generalized osteoarthritis (menopausal osteoarthritis) is commonly familial and is characterized by Heberden's nodes (DIP joint) and Bouchard's nodes (PIP joint)
Osteoarthritis with calcium pyrophosphate deposition usually affects elderly women, especially the knees, and is associated with inflammation and hypertrophic X-ray changes. Calcium hydroxyapatite associated destructive arthritis is confined to the shoulders (Milwaukee shoulder) and knees. It is associated with a poor outcome
Osteoarthritis of premature onset commonly occurs after trauma or following procedures such as meniscectomy. Multiple joint involvement in patients less than 50 years should prompt investigation for systemic conditions which may present with arthritis such as haemochromatosis, ochronosis, acromegaly and hereditary defects . Comorbid conditions require exclusion as a cause of symptoms such as soft tissue lesions (bursitis, enthesitis), fibromyalgia, crystal deposition disease, inflammatory arthritis and joint sepsis.
Radiography of the affected joints
The diagnosis of osteoarthritis is heavily reliant upon typical changes on the plain radiographs. Classic changes include joint space narrowing (due to cartilage loss), bony sclerosis, osteophytosis (the bony response to injury) and bone cysts). These changes may not be detected by X-rays in patients with early disease. Usually, the plain X-ray is sufficient to confirm the diagnosis but there may be large discrepancies between symptoms and radiological change.
MRI is sensitive for early changes of osteoarthritis. It is not routinely indicated but may be helpful when the plain X-ray is normal to screen for synovitis.
Investigating other causes of arthritis
The differential diagnosis of hydroxyapatite associated destructive arthritis includes Charcot arthropathy, avascular necrosis and joint sepsis, which require exclusion with appropriate investigation.
If an effusion is present, aspiration of the joint is paramount to exclude the presence of an inflammatory disorder, crystal disease and sepsis.
Patient education on the natural history of the disease is an important aspect of management. Self-management programmes and regular telephone contact with a professional have been shown to significantly ameliorate patient anxiety and to reduce the need for more intensive medical intervention.
Physiotherapy and occupational therapy
Assessment by physiotherapists and occupational therapists is important for joint protection, strengthening of the supporting muscle structures, appropriate footwear (orthoses, insoles), knee bracing and walking aids.
Weight control and exercise
Other modalities include weight control and general exercise programmes.
Pain control is the principal reason for patient presentation. Initial pharmacological therapy involves the use of paracetamol (acetaminophen) followed by escalating use of non-steroidal anti-inflammatory drugs (NSAIDs, oral and topical), codeine derivatives, tramadol and stronger opioids. As symptoms are often episodic, intermittent use of analgesics may suffice. Topical analgesic and anti-inflammatory creams include capsaicin and methyl salicylate. Despite being recommended, the efficacy of paracetamol in osteoarthritis has been questioned.
Intra-articular corticosteroids are indicated for those with an inflammatory component, however the effect is usually short-lived (weeks).
Viscosupplementation with intra-articular hyaluronic acid injections has been found to be effective in mild to moderate osteoarthritis of the knee. Symptomatic slow-acting drugs for osteoarthritis (SYSADOA) such as glucosamine sulphate have been demonstrated to reduce the progression of osteoarthritis in the lower limbs. Preliminary results obtained in patients with osteoarthritis of the hands suggest that chondroitin sulphate may also have disease-modulating effects although further studies are required to truly determine the usefulness of these agents. Studies so far with these chemical entities (nutripharmaceuticals) have utilized prescription formulations, not over-the-counter compounds or food supplements.
Arthroscopy, synovectomy/debridement, arthroplasty, osteotomy, arthrodesis, tendon repair and nerve decompression are some of the surgical procedures available. Patients with persistent synovitis of large joints may benefit from either surgical or chemical synovectomy with yttrium-90.
The natural history of osteoarthritis is poorly documented. There is evidence that the process may stop or even improve. Progressive disease causes weight-bearing joint failure in only a minority.
With appropriate therapy the prognosis of osteoarthritis is favourable, especially in patients with generalized nodal disease. Patients with mild disease can be effectively managed with simple analgesics and education whereas severely damaged joints can be renewed with joint arthroplasty. Hydroxyapatite associated joint disease has a poor prognosis in terms of joint function.
radiological appearance of osteoarthritis hand
comparison of normal and osteoarthritis x ray
Principle behind osteoarthritis
Prevalence of osteoarthritis
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