The hip is one of the largest weight-bearing joints in our body, allowing us to walk, run, sit comfortably, and carry out nearly all of our daily activities. As a ball-and socket joint, there are two main parts of the hip: the femoral head (a ball-shaped bone located at the top of your thigh bone) and the acetabulum (a cup-like socket in your pelvis). The femoral head and acetabulum are both covered with articular cartilage which allows for friction-free movement of the joint. Around the rim of the acetabulum, there is another layer of a different type of cartilage, known as the labrum, which serves to deepen the socket.
When cartilage loss occurs at the hip, there can be significant pain. Hip pain is a somewhat vague symptom, though. Hip arthritis is among the common causes of hip pain. Other causes include injury, fracture, bursitis, avascular necrosis, and possibly even back problems.
It is important to pin down the cause of hip pain so your condition can be properly treated. With hip arthritis, appropriate treatment will help you manage pain and other symptoms, slow disease progression, reduce physical limitations that can interfere with usual activities, and prevent disability.
Symptoms of Hip Arthritis
Usual signs and symptoms associated with hip arthritis include:
- Joint stiffness
- Limited range of motion
- Pain in the groin or, less commonly, the buttocks which can radiate down the thigh to the knee
- Pain that typically worsens when walking, standing, or climbing stairs
Physical Examination of the Hip
If you are experiencing persistent hip pain, you need to consult with your doctor. Your doctor will perform a physical examination and likely order x-rays to help diagnose the problem. With hip arthritis, x-rays will reveal how much joint space narrowing has developed. Severe cartilage loss can lead to an abnormality, commonly called bone-on-bone, which is excruciating.
The physical examination will include observation of your gait, passive range of motion, and checking the buttocks and thigh for signs of muscle atrophy. Functional motion is evaluated while you are weight bearing (i.e., walking and standing). People with hip arthritis tend to have a classic gait, swinging their pelvis forward quickly on the affected side, in order to minimize painful weight bearing.
While lying on your back, your doctor will test passive range of motion by log rolling the extended leg. With the knee and hip flexed to 90 degrees, internal and external rotation of the leg are checked.
Significant pain and diminished motion on internal rotation are considered likely indicators of hip arthritis. For people with longterm, severe hip arthritis, there is usually evidence of flexion contracture of the hip (i.e., inability to fully extend the hip) as well.
Differentiating Hip Osteoarthritis and Inflammatory Arthritis of the Hip
Hip osteoarthritis develops when cartilage wears away at the the ends of the bones that form the joint. There can be inflammation that develops as cartilage wears away. With inflammatory arthritis of the hip, the joint lining becomes inflamed (i.e., synovitis) and causes damage to the joint. Rheumatoid arthritis, ankylosing spondylitis and related conditions, and systemic lupus erythematosus are three inflammatory types of arthritis that frequently affect the hip.
With inflammatory hip arthritis, pain is typically worse in the morning and decreases with activity, although vigorous or strenuous activity can increase pain and stiffness. With hip osteoarthritis, pain typically worsens when you are active and lessens when you rest.
Treatment for Hip Arthritis
Conservative, non-surgical treatment is tried before surgical treatment is considered, in most cases. Conservative treatment includes rest, medications, physical therapy, and weight management. Hip replacement surgery may be considered when conservative treatments have produced inadequate results.
Primer on the Rheumatic Diseases. Thirteenth Edition. Klippel J. MD, et al. Arthritis Foundation.
Inflammatory Arthritis of the Hip. OrthoInfo. AAOS. August 2007.
Osteoarthritis of the Hip. OrthoInfo. AAOS. August 2007.