Osteoarthritis of the hip joints (coxarthrosis)

Definition of the disease. Causes of the disease

Coxarthrosis, or osteoarthritis of the hip joint, is a chronic degenerative joint disease that leads to deformation of the bone tissue. In coxarthrosis, all components of the joint are involved in the pathological process: joint cartilage, bone structures adjacent to the cartilage, synovial membrane, ligaments, capsule, and muscles adjacent to the joint. The disease involves the destruction of the articular cartilage, the appearance of microfractures of the bones, osteophytes (bone outgrowths), and inflammation of the muscular-ligamentous apparatus of the hip joint.

One in every five people worldwide complains of joint problems. This can manifest as pain, restricted movement in the joints, or a combination of these symptoms. Every second outpatient visit in Russia is for patients with musculoskeletal disorders, with 66% of cases involving individuals under 65 years of age. According to the latest epidemiological study, the prevalence of osteoarthritis of the knee and hip joints among the adult population is 13%.

Risk factors for the development of coxarthrosis:

1. Genetic predisposition: A common cause of coxarthrosis of the hip joints is a congenital or acquired mutation in the type II procollagen gene.
2. Elderly age: The probable reason for the prevalence of osteoarthritis in old age is the mismatch between the damaging effect on joint cartilage from the external environment and its ability to recover.
3. Gender: Women suffer from osteoarthritis more often than men due to the influence of female sex hormones (estrogens) on bone mineral metabolism. However, the influence of gender is not straightforward — according to some authors, unlike other joint lesions, there are no gender differences for coxarthrosis: it occurs in men as often as in women.
4. Excess body weight: There is a correlation between excess body weight and the development of osteoarthritis. Excess adipose tissue increases damaging load on the cartilage and also produces pro-inflammatory enzymes that damage cartilage tissue.
5. Developmental bone and joint abnormalities: According to studies, 80% of coxarthrosis occurring without visible causes is associated with previously undiagnosed developmental abnormalities of the hip joint, such as dysplasia and subluxations.
6. Heavy physical labor: Excessive stress on the hip joints during certain types of physical labor can lead to joint damage and the formation of osteoarthritis. Agricultural workers, miners, and people with similar occupations are at risk.
7. Injuries: The risk of developing coxarthrosis increases after injury to the hip joint. Both one injured joint and both joints can be involved in the process.
8. Professional sports: Professional sports can provoke the development of coxarthrosis due to excessive joint stress and injuries. Potentially dangerous sports include weightlifting, long jump in athletics, and skydiving.
9. Bone and joint diseases: Rheumatoid arthritis, psoriatic arthritis, joint infections, avascular necrosis, gouty arthritis, and others.
10. Endocrine pathologies: Hypothyroidism, hypoparathyroidism, acromegaly (disorder of the anterior pituitary function), diabetes mellitus, obesity.

Symptoms of hip osteoarthritis:

• Pain: Varied in intensity, initially mild and short-lived, exacerbated during activities like walking, squatting, bending, or lifting weights. Pain worsens with disease progression, persists even during rest, and may occur after prolonged immobility. Patients often experience “start-up” pain in the hip joints after sleeping, driving, or prolonged immobility, lasting no more than 30 minutes. Pain can be localized in the buttocks, groin, anterior or lateral thigh, radiating to distant areas such as the lower back, sacrum, coccyx, or knee. Pain may increase with cold exposure or stress.
• Limited joint mobility: Movement in the hip joint is restricted due to pain, affecting rotation (both inward and outward), adduction (movement toward the body’s midline), abduction (movement away from the body’s midline), flexion, and extension. Inability to perform passive movements due to severe pain leads to compensatory pelvic tilt. The patient’s gait changes, with the buttocks protruding backward, and the body leaning forward when weight is shifted to the affected side. Bilateral involvement results in a characteristic “waddling gait.”
• Periodic joint swelling: Occurs in the joint area, sometimes unnoticed due to muscle and fat layers.
• Joint crepitus: Crackling or popping sounds during movement.
• Gradual joint deformity and functional shortening of the lower limb.

Often, one joint is initially affected, with the condition later spreading to others. In some cases, osteoarthritis affects multiple joints simultaneously, leading to polyosteoarthritis. Polyosteoarthritis is common in elderly individuals or those with a hereditary predisposition and concurrent bone, joint, or endocrine disorders.

Classification and stages of development of hip osteoarthritis:

Depending on the causes of the disease, coxarthrosis is divided into two main forms: primary (idiopathic) and secondary (occurring against the background of or due to other diseases).

Primary coxarthrosis:

1. Localized (affects only the hip joints):

• Unilateral
• Bilateral

1. Generalized (polyosteoarthritis) with involvement of at least three joint groups (e.g., hip, knee, and small joints of the hands or feet).

Secondary osteoarthritis:

1. Post-traumatic:

• Acute: Resulting from acute trauma.
• Chronic: Due to certain sports activities or professional activities.

1. Metabolic diseases (ochronosis, hemochromatosis, Wilson’s disease, Gaucher’s disease).
2. Congenital pathologies and developmental defects (congenital dysplasia of the hip joint, Perthes disease, slipped capital femoral epiphysis, hypermobility syndrome, lower limb shortening, scoliosis, bone dysplasia).
3. Endocrine pathologies (acromegaly, hypothyroidism, diabetes mellitus, hyperparathyroidism, obesity).
4. Calcium salt deposits (pyrophosphate arthropathy, calcific tendinitis).
5. Bone and joint diseases (rheumatoid arthritis, psoriatic arthritis, Paget’s disease, avascular necrosis, infections).

Clinical forms of coxarthrosis can be distinguished based on clinical manifestations:

1. Mildly symptomatic.
2. Manifest, characterized by prominent clinical symptoms:

• Rapidly progressing: Symptoms develop within the first four years of the disease.
• Slowly progressing: Clinically significant symptoms appear after five years of disease progression.

According to radiological findings, two types of hip osteoarthritis can be distinguished:

• Hypertrophic: With signs of increased reparative response (lesions are replaced by new tissue, such as osteophytes).
• Atrophic (decrease in tissue volume).

The stages of the disease can be determined radiologically and clinically. The Kellgren and Lawrence classification (1957) is often used to determine the radiological stage of hip osteoarthritis.

Radiological stages of hip osteoarthritis:

• Stage 0: No signs of osteoarthritis on X-rays.
• Stage 1: Joint space is unchanged, with occasional marginal osteophytes.
• Stage 2: Joint space is unchanged, with significant marginal osteophytes.
• Stage 3: Moderate reduction in joint space, with significant marginal osteophytes.
• Stage 4: Significant reduction in joint space, with significant marginal osteophytes and subchondral sclerosis.

The clinical stage of the disease is determined using the Kosinskaya classification (1961), which incorporates both clinical signs and visualization criteria.

Complications

1. Complications of coxarthrosis are all related to pathological changes in the joints. The course of coxarthrosis can be complicated by local inflammatory processes, including:
– Bursitis: inflammation of the synovial sacs around the joints.
– Tenosynovitis: inflammation of the inner lining of the tendon sheath of muscles.
– Tunnel syndrome: nerve compression due to the formation of large osteophytes or joint deformities.

2. As coxarthrosis progresses to its second and third clinical stages, joint pain limits mobility, eventually leading to joint ankylosis (fibrous, bony, or cartilaginous fusion), resulting in complete immobility. Significant joint deformity can lead to fractures or aseptic bone necrosis, with aseptic necrosis of the femoral head being the most serious complication. Severe coxarthrosis may result in joint dislocations, hip joint subluxations, or even the penetration of the femoral head into the pelvic cavity. Dislocations and subluxations of the hip joint cause pain (initially acute, then dull and aching), worsened by walking and other physical activities, leading to joint deformity, limping, and sometimes shortening of the affected limb.

3. Despite the absence of systemic manifestations of arthritis itself, modern clinical practice increasingly focuses on associated diseases. These are pathological conditions that exist or arise against the background of the current disease. Inflammatory reactions associated with arthritis can increase the formation of atherosclerotic plaques on the inner walls of blood vessels, raising the risk of cardiovascular diseases. Reduced physical activity due to pain and joint immobility can lead to obesity, depression, and a decreased quality of life. Prolonged use of nonsteroidal anti-inflammatory drugs can damage the upper gastrointestinal tract and increase the risk of cardiovascular and kidney diseases.

Diagnosis of hip osteoarthritis

Diagnosis of hip osteoarthritis is based on clinical manifestations and radiological examination. There are no specific laboratory markers for diagnosing osteoarthritis.

The main clinical manifestations for diagnosing hip osteoarthritis are pain and its characteristics. Pain gradually develops and intensifies over several years, sometimes over several months in rapidly progressive forms. It worsens with physical activity or in a weight-bearing position. If a patient experiences pain at rest, it may indicate inflammation (synovitis). Additionally, stiffness is observed for up to 30 minutes in the mornings and with prolonged immobility.

There is a gradual restriction of joint mobility, affecting both active and passive movements. As the disease progresses, joint deformities develop, and functional shortening of limb length may occur. Physical examination reveals limited joint mobility, joint deformity, limb shortening, tenderness upon palpation of the joint and greater trochanter of the femur, and muscle atrophy.

Laboratory methods are not required for diagnosing hip osteoarthritis, but they can be used for differential diagnosis between osteoarthritis and arthritis (rheumatoid and chronic). Instrumental methods include:

• Radiography: the primary diagnostic method, which identifies characteristic signs of osteoarthritis such as joint space narrowing, osteophytes, erosions, subchondral cysts, and sclerosis. Radiographic examination is the classic method of diagnosing hip osteoarthritis, and radiographic signs form the basis of its classification. However, other visualization methods such as ultrasound and magnetic resonance imaging (MRI) are increasingly used.
• Ultrasound examination (US): offers the advantage of visualization without radiation exposure.
• Magnetic resonance imaging (MRI): allows for clearer visualization of joint damage compared to other methods.
• Arthroscopy: detects various degrees and types of joint cartilage damage, including the formation of deep ulcers, cracks, and erosions.

Detecting hip osteoarthritis typically does not pose significant challenges, but when evaluating a specific clinical situation, it is essential to consider the possibility of secondary origin of hip osteoarthritis (as a complication of other diseases, such as endocrine disorders).

Treatment of hip osteoarthritis can be either conservative (pharmacological and non-pharmacological) or surgical. Conservative treatment is used in stages 1-2 of the disease, while surgery is reserved for stage 3. Surgical intervention may also be recommended at stage 2 in cases of persistent pain and lack of response to conservative therapy.

The goals of conservative therapy are to improve quality of life by reducing pain and increasing joint mobility, as well as to halt or slow the progression of the disease. Non-pharmacological treatment methods include:

• Unloading of the hip joint (weight reduction, providing additional support, and transferring some of the body weight to a cane or crutches).
• Physical therapy.
• Physiotherapeutic treatment methods.

Treatment

Treatment of hip osteoarthritis typically begins with non-pharmacological methods, with therapeutic exercise playing a crucial role. Patients with severe pain should use support. In cases of advanced disease and contraindications to joint replacement surgery, lifelong support may be necessary.

Pharmacological therapy for hip osteoarthritis includes medications that alleviate disease symptoms. These include analgesics such as paracetamol, as well as non-steroidal anti-inflammatory drugs (NSAIDs). NSAIDs are divided into non-selective (indomethacin, diclofenac, ibuprofen) and selective (nimesulide, meloxicam) categories.

Analgesics and NSAIDs for hip osteoarthritis are used temporarily to relieve pain and inflammation. Currently, there is no proven advantage of one NSAID over another, so the choice of a specific drug depends on its side effects and the individual clinical situation.

It is important to remember that NSAIDs have a range of side effects. Their use may lead to gastric and duodenal mucosal damage, resulting in ulceration and bleeding. Some NSAIDs have toxic effects on the liver and kidneys. Additionally, NSAIDs inhibit platelet aggregation, leading to impaired blood clotting and an increased risk of bleeding. Selective NSAIDs cause fewer complications.

Topical ointments and gels have fewer side effects than oral medications. These products, containing ingredients like camphor, menthol, nicotinic acid esters, salicylates, bee venom, or capsaicin, provide pain relief. Additionally, NSAID applications (indomethacin, diclofenac, voltaren) have a beneficial effect.

If paracetamol and NSAIDs are ineffective, or if an optimal dose cannot be determined, centrally acting analgesics may be prescribed temporarily. Tramadol, for example, is administered at a dose of 50-200 mg/day, with dosage adjustments made by gradually increasing it by 25 mg.

In cases of inflammation, intra-articular corticosteroid injections (diprospan, dexamethasone, kenalog) may be used. Corticosteroids are administered no more than 2-3 times per year, as more frequent use may lead to cartilage degeneration.

Slow-acting drugs that alleviate disease symptoms include chondroitin sulfate, glucosamine, avocados or soy unsaponifiables, and hyaluronic acid. These drugs are recommended by the European League Against Rheumatism for treating hip osteoarthritis. They reduce pain and improve joint mobility.

Total hip replacement surgery is performed in severe cases of stage 3 osteoarthritis, when pain cannot be alleviated, and joint mobility is significantly limited. Hip replacement surgery leads to reduced pain, improved joint function, and better quality of life for the patient. The effect lasts for 10-15 years, after which repeat surgery may be required. During the procedure, the hip joint is replaced with an artificial implant made of ceramic, metal (most commonly titanium implants), or polymer.