Everything You Need to Know About Osteoarthritis

Osteoarthritis is a degenerative joint disease, which is always characterized by both, the degeneration of articular cartilage and simultaneous proliferation of new bones, cartilage, and connective tissue. It is not a single disease rather it is the result of various joint failure. The proliferative responses result in some degree of remodeling of the joint contour. Inflammatory changes in the synovium are usually minor and secondary. It is characterized by a slow and progressive focal erosion, and later more extensive destructive of the articular cartilage, followed by subchondral sclerosis and the formation of large body spurs as protrusions (osteophytes) at the margin of the affected joints.

This disease is uncommon before the age of 40 years. It affects both male and female and is more generalized and more severe in elder women. If affects mainly the articular cartilage of the big weight-bearing joints like spine, knee, and hip. The small joints of the hands and feet are also often involved. The osteophytes may contribute to the pain and disability, but they never fuse to cause ankylosis of the joint. When they occur at the distal interphalangeal joint, they are called Heberden's osteoarthritis.

Types of Osteoarthritis

1. Primary Osteoarthritis: In this type, there is no obvious predisposing cause evident. There is a presumptive abnormality of chondrocyte metabolism, but it is essential to nature obscure. A familial pattern is apparent in some cases.

2. Secondary Osteoarthritis: In this, there is a clear association with some predisposing conditions, which may be virtually any abnormality of the joint as follows:

• Alteration of the joint mechanism, for example, abnormal ligament and angulation. A severe form is seen when the nerve supply to a joint in neuropathic arthropathy.

• Abnormality of the articular surface, for example, injury.

• An abnormal stress of the joint, for example, increased weight-bearing demand due to obesity, association with a particular occupation.

• Previous inflammation, for example, sepsis, rheumatoid, etc.

Classification of Osteoarthritis

I) Idiopathic:

A) Localized Osteoarthritis:

1. Hand: Heberden's and Bouchard's nodes, erosive interphalangeal arthritis, first carpometacarpal joint.

2. Feet: Hallux valgus, Hallux rigidus, contracted toes (hammer/cockup toes), talonavicular.

3. Knee: Medial compartmental, lateral compartment, patellofemoral compartment.

4. Hip: Eccentric (superior), concentric (axial, medial), diffuse (coxae senilis).

5. Spine: Apophyseal joint, intervertebral joint (disc), spondylosis (osteophytes), ligamentous (hyperostosis, Forestier's disease, diffuse idiopathic skeletal hyperostosis).

B) Generalized Osteoarthritis: When the affected joint include three or more of the area listed above, it is known as generalized osteoarthritis.

II) Secondary:

A) Trauma:

1. Acute.

2. Chronic (occupational, sports).

B) Congenital Development:

1. Localized disease: Legg-Calve-Perthes disease, congenital hip dislocation, and slipped epiphysis.

2. Mechanical factors: Unequal lower extremity length, hypermobility syndrome.

3. Bone dysplasias: Epiphyseal dysplasia, spondyloepiphyseal dysplasia, and osteodystrophy.

C) Metabolic:

• Ochronosis (alkaptonuria), hemochromatosis, Wilson's disease, Gaucher's disease.

D) Endocrine:

• Acromegaly, diabetes mellitus, hyperparathyroidism, obesity, hypothyroidism.

E) Calcium Deposition Disease:

• Calcium pyrophosphate dihydrate deposition disease, apatite arthropathy.

F) Neuropathic:

• Charcot's joints.

G) Miscellaneous:

• Frostbite, Caisson's disease, hemoglobinopathies.

Differential Diagnosis of Joint Disorders

• Rheumatoid Arthritis: It presents initially with swollen, painful, stiffness of hands and feet. Eventually, characteristic hand deformities with swelling of metacarpophalangeal joints, swan neck, boutonniere deformities, and ulnar deviation occur. Large joints are also involved eventually. The patient may complain of extra-articular manifestations, that is, rheumatoid nodules, vascular changes, eyes changes or neuropathies.

• Psoriatic Arthropathy: It usually follows several years after the skin lesions. Reiter's disease may present with arthritis in single joints or a few joints. There will be a history of sexual contact, urethritis, and conjunctivitis.

• Rheumatic Fever: It usually follows a streptococcal infection, for example, scarlet fever or tonsillitis. There is a migratory polyarthritis together with carditis, erythematous skin lesions, and subcutaneous nodules.

• Gout: It presents with severe pain, redness, and swelling in the first metatarsophalangeal joint. It may affect other joints. There may be a history of polycythemia, leukemia or medication with cytotoxic or immunosuppressive drugs.

• Ankylosing Spondylitis: It presents in young males and initially presents with morning stiffness in the spine. The sacroiliac joint are involved. Eventually, bony ankylosis occurs with a fixed kyphotic spine. The patient may also complain of symptoms in the hip and knee. Arthritis may occur in SLE (systemic lupus erythematosus). Other manifestation may be present, for example, cutaneous, pulmonary or renal.

• Septic Arthritis: It presents as a monoarthritis with a red, swollen, painful, immobile joint. Spread has usually occurred by the hematogenous route but may occur from adjacent osteomyelitis.

• Tubercular Arthritis: The patient usually presents with swelling and stiffness of the joint. It is not as red or hot as with acute septic arthritis. Patients who are on steroids or who are immunosuppressed are particularly at risk from infective arthritis.

• Osteoarthritis: It usually occurs after the age of 50 years unless it is secondary to previous joint pathology. The patient complains of pain on movement, which is worse at the end of the day, together with stiffness, swelling, and instability of joints.

Epidemiology and Risk Factors of Osteoarthritis

Osteoarthritis is one of the most common joint diseases. In developing countries, knee osteoarthritis is the leading cause of chronic disability among the elders. Age is one of the risk factors for osteoarthritis. In a radiographic survey of women less than 45 years old, only 2 % had osteoarthritis, between the ages of 45 to 65 years it was 30 % and those above 65 years it was 68 %. In males, the figure was similar but somewhat lower in older age group.

1. Under the age of 55 years, the joint distribution of osteoarthritis in men and women is similar.

2. In older individuals, hip osteoarthritis is more common in men.

3. Osteoarthritis of interphalangeal joint and the thumb is more common in women.

4. Radiographic evidence of knee osteoarthritis and especially symptomatic knee osteoarthritis is more common in men than in women.

5. Trauma and repetitive joint use are also important risk factors for osteoarthritis. Anterior cruciate ligament insufficiency and meniscus damage may lead to knee osteoarthritis. A person with a trimalleolar fracture will almost certainly develop ankle osteoarthritis.

6. Ankle osteoarthritis is common in ballet dancer

7. Elbow osteoarthritis is common in basket pitcher.

8. Metacarpophalangeal osteoarthritis is common in prizefighter.

In general population, osteoarthritis is not very common at any of these sites. In contrast, vocational activities such as those performed by jackhammer operation, cotton mill and shipyard worker and coal miner may lead to osteoarthritis in the joint which is rapidly exposed due to occupational use. Obesity is a risk factor for knee osteoarthritis. For those in the highest quintile for body mass index at baseline examination, the relative risk of developing knee osteoarthritis by 36 years was 1.5 for men and 2.1 for women. In obesity, the relative risk rose to 1.9 for men and 3.2 for women suggesting that obesity plays a large role in the etiology of the most serious case of knee osteoarthritis. Further, a more obese individual who has not yet developed osteoarthritis can reduce the risk. A weight loss of 5 kg was found to be associated with 50 % reduction in the acts of developing symptomatic knee osteoarthritis.

Pathology of Osteoarthritis

It is not a disease of a single tissue, but the synovial joint as a whole is affected. The morphologic change in osteoarthritis is mostly seen in the articular cartilage of the weight bearing bones. The cardinal pathologic feature of osteoarthritis is a progressive loss of articular cartilage.

Changes in Articular Cartilage:

In the beginning, there is a loss of cartilaginous matrix (proteoglycans) resulting in progressive loss of normal metachromasia. This is followed by focal loss of chondrocyte and at other place proliferation of chondrocyte forming clusters. Further progression of the process causes loosening, flaking, and assuring of the articular cartilage resulting in breaking of pieces of cartilage exposing subchondral bones. Radiologically, this progressive loss of cartilage is apparent as narrowed joint space.

Changes in the Bone:

The denuded subchondral bone appears like polished ivory. There is a death of superficial osteocytes and increase osteoblastic activity causing rarefaction, microcyst formation, and occasionally microfracture of the subjacent bones. This changes result in remodeling of bones and changes in the shape of the joined surface leading to flattering and mushroom like an appearance of the articular end of the bones. The margins of the joints respond to cartilage damage by osteophytes or spur formation, these are cartilaginous outgrowth at the joint margin that later gets ossified. Osteophytes give the appearance of lipping of the affected joint loosened, and fragmented osteophytes may form free joint mice or loose bodies.

Changes in the Synovium:

Initially, there are no pathologic changes in the synovium, but in advanced cases, there is low-grade chronic synovial effusion associated with chronic synovitis.

Etiology of Osteoarthritis:

According to the etiology, there are two types of osteoarthritis.

1. Primary Osteoarthritis: Here the etiology is unknown.

2. Secondary Osteoarthritis: Here the degenerative joint changes occur inresponse to a recognizable local or systemic factor.

Causes:

Developmental:

1. Slipped femoral epiphysis.

2. Epiphysiolysis.

3. Hip dysplasia.

4. Intra-articular acetabular labrum.

5. Perthes disease.

Traumatic:

1. Intra-articular fracture.

2. Menisectomy.

3. Occupational, for example, the elbow of a pneumatic drill.

Metabolic:

1. Alkaptonuria (ochronosis).

2. Hemochromatosis.

3. Wilson's disease.

4. Chondrocalcinosis.

Endocrine:

1. Acromegaly.

Inflammatory:

1. Rheumatoid arthritis.

2. Gout.

3. Septic arthritis

4. Hemophilia

Aseptic Necrosis:

1. Corticosteroid.

2. Sickle cell disease.

3. Decompression sickness.

4. SLE (systemic lupus erythematosus) and other collagenous.

5. Neuropathy.

6. Tabes dorsalis.

7. Syringomyelia.

8. Diabetes mellitus.

9. Peripheral nerve lesion.

Clinical Features of Osteoarthritis

The joints most frequently involved are those of weight-bearing bones like spine, hips, knees, and hands. The disease is confined to one or only a few joints in the majority of patients. The clinical features of osteoarthritis vary as follows:

Primary Generalised Osteoarthritis:

It has a gradual onset. And the pain is deep aching, intermittent at first but becomes persistent afterward. The pain increased by joint use and decreases by rest. In advanced osteoarthritis, nocturnal pain may be seen which interferes with sleep. The causes of pain are:

1. Synovial inflammation.

2. Microfracture of subchondral bones.

3. Stretching of periosteal nerves by osteophytes.

4. Stretching of the ligament.

5. Inflammation and distension of capsule.

6. Muscles spasm sign like localized tenderness of the joint.

7. Bony crepitus of joints is characteristic.

8. Warmth over the affected joint.

9. Periarticular muscles atrophy.

Advanced Stage of Osteoarthritis May Have:

1. Gross deformity.

2. Bone hypertrophy.

3. Subluxation.

4. Marked loss of joint motion.

Nodal Osteoarthritis:

This is clinically from primary generalized osteoarthritis, which occurs predominantly. The affected joints are terminal interphalangeal joints of the finger with the development of generalized gelatinous cysts or bony outgrowth on the dorsal aspect of these joints (Heberden's nodes). It has an acute onset, with pain and swelling. Heberden's nodes seldom cause serious disability. The similar lesion may affect proximal interphalangeal joints called Bouchard's nodes. The disorder also frequently involves in the carpometacarpal joints of the thumb, the spinal epiphysial joints, the hip and the knees. A strong family history of Heberden nodes is usually single autosomal dominating gene. Patient with nodal primary generalized osteoarthritis is more susceptible to secondary osteoarthritis.

Erosive Osteoarthritis:

This is a more severe form of nodal primary generalized osteoarthritis. It has episodic symptoms and signs of local joint inflammation with development of destructive subchondral erosion and instability in the proximal and the distal interphalangeal joints.

Non-Nodal Primary Generalized Osteoarthritis:

It is characterized by an equal sex incidence and less prominent distal interphalangeal joint disease.

Osteoarthritis of the Knee Joint:

This is often associated with obesity. Isolated knee osteoarthritis may, however, be a consequence of various knee deformities associated with medial meniscectomy and dysplasia such as Blount's disease.

Isolated Hip Osteoarthritis:

This is frequently secondary to some predisposing causes such as inequality of leg length, preceding hip disease, acetabular dysplasia or occupational trauma. The superior pole hip is typically affected in such cases whereas hip disease in primary generalized osteoarthritis is usually medial or concentric.

Investigation of Osteoarthritis:

The diagnosis of osteoarthritis is usually based on clinical and radiographic features. Following are the investigation done to diagnosis osteoarthritis.

Radiological: X-ray of affected joint is the most significant investigation for osteoarthritis. The most important changes in the x-ray are:

1. Narrowing of the joint space due to loss of cartilage.

2. Formation of osteophytes at the margin of the joint.

3. Sclerosis of the underlying bone and cyst formation.

4. There is often calcification which takes one of the two forms. Linear calcification which is characterized bypyrophosphate deposition. Spotty calcification which is characterized by hydroxyapatite deposition.

Synovial fluid study:

1. The fluid is viscous and has a low cell count.

2. Cartilage degradation products such as keratin sulfate and pyridazine cross-links derived from collagen are increased in the synovial fluid and urine but not useful in diagnosis.

Blood: Blood count and ESR (erythrocyte sedimentation rate) are characteristically normal. Isotope scintigraphy with 99 m TC bisphosphonate shows increased uptake of isotope in osteoarthritis joint that is destined to develop progressive damage.

Management of Osteoarthritis

The treatment of osteoarthritis is aimed at reducing pain, maintaining mobility, minimizing disability, and thus improving the function of the joint. The patient education and encouragement of a positive approach are particularly important in osteoarthritis. The pathological changes of osteoarthritis are irreversible, the overall prognosis for maintaining function is generally good, and a great deal can be done to alleviate symptoms by the following.

1. Improving muscle strength.

2. Maintaining mobility of the affected joint.

3. Avoidance of trauma and physical stress to the affected joint.

Reduction of Joint Loading:

Osteoarthritis may be caused and aggravated by poor body mechanics. So following precautions are necessary.

1. Corrections of poor postures and support for excess lumbar lordosis can be helpful.

2. Excessive loading of the involved joint should be avoided.

3. For patients with medial compartment knee osteoarthritis, a wedged insole may reduce joint pain.

4. Patient with osteoarthritis of the knee or feet should avoid prolonged standing, kneeling, and squatting.

5. Running shoe may also be helpful in cushioning the load.

Physical Therapy:

1. Application of heat may reduce pain and stiffness.

2. Hot shower or bath is helpful.

3. Sometimes better analgesia may be obtained with ice than with heat.

Exercise:

Exercise should be designed to maintain range of motion as well as to strengthen muscles surrounding the joint.

1. Isometric exercise are generally preferable than isotonic exercise since they minimize joint stress.

2. Incase of moderately severe knee osteoarthritis, strengthening of quadriceps and hamstring muscles by can isometric exercise programme significantly decrease the joint pain.

3. In control group that perform range of motion, exercise has no gain in muscle strength and knee pain worsen during the period of observation.

4. Hydrotherapy is particularly useful for hip joint, sometimes enabling a stiff joint to be mobilized and providing symptoms relief.

5. A walking stick is useful for a patient involvement of one hip or knee and should be held in the opposite hand.

Joint protection technique

1. Fitting of rubber heels to reduce jerking and minimize the risk of slipping.

2. Built up shoes to equalize leg length.

3. Weight reduction in obese patients with osteoarthritis of the knee and hip.

4. Use of suitable walking stick.

5. Occasionally patients are advised to change their occupation, transfer to lighter work or give up unduly strenuous hobbies.

6. Modifications of existing activities to avoid prolonged standing or walking is all that is required.

Incase of Obese Patient:

1. Weight reduction.

2. Dietary restriction sufficiently to 28 % decrease in body weight results in 40 % reduction in the severity of osteoarthritis lesion.

Rest:

1. Rest during the day may be beneficial.

2. Complete immobilization of the painful joints is rarely indicated.

• In unilateral hip or knee osteoarthritis, a cane held in the contralateral hand may reduce joint pain by reducing the joint contact force. In bilateral it may be necessary to use a crutch or a walker.