Hip Osteoarthritis

Hip osteoarthritis is a common, long-term condition that affects the hip joint. It develops when the smooth protective cartilage that covers the ends of the bones in the hip gradually wears down. This cartilage normally allows the hip to move smoothly and absorb shock during everyday activities such as walking, sitting, bending, and climbing stairs. When cartilage becomes thinner or damaged, hip function is impaired, leading to pain, stiffness, and reduced range of motion.

The hip joint is a “ball-and-socket” joint. The ball is the top of the thigh bone (femoral head), and the socket is part of the pelvis (acetabulum). In a healthy hip, cartilage covers both surfaces, and a small amount of joint fluid helps lubricate the joint. In hip osteoarthritis, cartilage loss, changes in the underlying bone, and inflammation of the joint lining all contribute to symptoms.

How Does Hip Osteoarthritis Impact Your Anatomy and Health?

Hip osteoarthritis can cause significant hip pain, making it difficult to perform everyday activities such as walking, climbing stairs, putting on shoes and socks and rising from a seated position. The cartilage that cushions the joint can wear away, resulting in bone-on-bone contact, inflammation and stiffness. In advanced stages, bone spurs called osteophytes can form around the joint, reducing mobility and increasing pain.

Risk Factors for Hip Osteoarthritis

Hip osteoarthritis can affect people of all ages and genders. However, several factors increase the risk of hip osteoarthritis, including age, obesity, family history of osteoarthritis, prior hip injuries or childhood hip conditions, and overuse of the hip joint. Anatomical differences in the way the hip joint has formed during growth can also increase a person’s risk of developing hip arthritis, including hip dysplasia or ‘cam’ deformity. Women are slightly more likely to develop hip osteoarthritis than men.

Causes of Hip Arthritis

Patients with osteoarthritis experience pain, stiffness, and loss of movement. This is due to

The progressive wearing of articular cartilage,
Narrowing of the joint space,
The formation of bone spurs around the edge of the femoral head or acetabulum,
Inflammation of the joint lining (synovitis), and
Thickening of the joint capsule.

Causes of hip arthritis include:

Natural cartilage Wear Due to Advancing Age,
Genetics,
Congenital or Developmental Hip Diseases,
Lifestyle factors such as obesity or occupational overuse,
Previous History Of Hip Injury Or Fracture,
Avascular necrosis (disruption of the blood supply to the bone), and
Autoimmune conditions such as rheumatoid arthritis and ankylosing spondylitis.

Degenerative Osteoarthritis

In most people with hip arthritis, the exact cause of the degeneration is unknown; this is referred to as degenerative osteoarthritis.

Cartilage Wear

As hip cartilage is degraded over time in osteoarthritis, it unfortunately has little capacity to regenerate. This is due to cartilage's inherently poor blood supply, which relies on the joint fluid for most of its nutrients. Over time, cartilage gradually deteriorates, which can lead to worsening symptoms.

For many patients, however, symptoms can ebb and flow with good periods of many months punctuating the gradual decline. With appropriate physiotherapy and analgesia, patients can often improve their pain and joint function despite the structural changes seen on imaging scans.

Hip Fractures

Older patients are more prone to hip fractures and deformities caused by osteoporosis as their bones become less dense and more brittle. Fractures around the hip often require hip replacement as the initial treatment, or if they are ‘fixed’, can still develop post-traumatic osteoarthritis requiring a hip replacement.

Femoral Acetabular Impingement (FAI)

Femoral acetabular impingement (FAI) is a cause of premature osteoarthritis. This may be the reason we see younger and younger patients developing osteoarthritis.

Genetic

There may be a genetic tendency in some people to develop osteoarthritis. This likely relates to genes that affect the collagen that makes up cartilage and helps explain why osteoarthritis affects some families more than others.

Rheumatoid Osteoarthritis and Other Autoimmune Arthritis

While the trigger of rheumatoid osteoarthritis is unknown, synovial inflammation can cause pain and, ultimately, joint degeneration. Although there are now many excellent modern medications used to treat rheumatoid arthritis, occasionally the hip joints may still degenerate and require Hip Replacement Surgery.

Avascular Necrosis

Avascular necrosis (AVN) can lead to degeneration of the hip joint. This disease is caused by a blockage of the blood supply to the bone of the femoral head. Bone is a living tissue and requires constant blood flow to provide it with oxygen and nutrients. Starved of nutrients, the hip’s femoral head dies and may collapse.

Most cases have no known underlying cause. Some cases are related to medications such as corticosteroids. Excessive alcohol consumption can also lead to AVN, as can trauma.

Perthes’ Disease

Perthes’ disease mainly affects children (3-11 years old). Poor blood supply (of unknown cause) causes softening and flattening of the femoral head. While most patients with Perthes’ disease recover and regenerate bone, the disease can result in a misshapen femoral head and socket that can predispose to early osteoarthritis.

Slipped Capital Femoral Epiphysis

Slipped capital femoral epiphysis (SCFE) is also known as Slipped Upper Femoral Epiphysis (SUFE). This condition primarily affects children aged 10-16 and involves slippage through the growth plate of the upper femur. It occurs gradually in the majority of patients and can lead to progressive deformity of the hip, causing limp, restricted hip movement and pain. In some patients, it occurs acutely, causing severe pain and inability to weight-bear.

Slipped capital femoral epiphysis requires surgical treatment when it is diagnosed to stop it from progressing or to realign the slipped femoral head in severe cases. Despite surgical treatment, the condition may result in deformity of the top of the femur, which can predispose to arthritis. Additionally, the condition or surgical treatment required can disrupt blood flow to the femoral head, leading to avascular necrosis and a subsequent need for hip replacement.

Developmental Dysplasia of the Hip

Hip dysplasia is a condition affecting newborns in which the hip joint is underdeveloped, resulting in a shallow hip socket. In its most severe form, the ball may be completely dislocated from the socket (about 1 in 1000), but in many cases, the hip is ‘stable’ but appears shallow on ultrasound or x-ray (30-50 per 1000).

If detected in infancy, the hip can usually be stabilised by bracing or early surgery, resulting in relatively normal future hip anatomy. If undetected or resistant to treatment, however, the hip may remain shallow into the teenage years when the skeleton stops growing. In a shallow hip joint, the socket has insufficient surface area to withstand the high forces of an active life, which can lead to labral tears, cartilage injury, and early arthritis. Adult hip dysplasia is one of the leading causes of hip replacement in people under 50.

Ankylosing Spondylitis

Although uncommon, this form of inflammatory arthritis can affect the hips and often the spine as well.

Typical symptoms include pain and stiffness upon awakening. Ankylosing spondylitis can occur by itself or in association with other disorders, including Crohn’s disease, ulcerative colitis and psoriasis.

Symptoms of Hip Osteoarthritis

Common osteoarthritis symptoms include

Pain in the hip joint (often felt in the groin but also deep in the side of the hip and often in the buttocks)
Radiating pain from the hip to the thigh and knee
‘Clicking’ or catching in the hip
Difficulty walking, resulting in a limp
Joint stiffness resulting in a reduced range of motion.

Hip pain can also be felt down the front of the leg, inner thigh and buttock (although problems with the lower back can also cause pain in this area). This is called referred pain, and it’s relatively common as the major nerves of the leg all pass by the hip and send in small sensory nerves. When these sensory nerves are triggered by the arthritis, it can trick the brain into thinking the problem is further down the leg, where the main part of the nerve is travelling.

Patients with hip arthritis classically describe:

A deep ache in the hip that is worse after an active day
Pain getting in and out of a car
Difficulty putting on shoes and socks
Pain at night in certain sleeping positions that reduces sleep quality
Pain with prolonged walking

People with hip arthritis often describe their life gradually becoming smaller as they slowly modify their plans and activities to accommodate their hip limitations.

Preventing Hip Osteoarthritis

While hip osteoarthritis cannot always be prevented, particularly when genetics or joint morphology play a role, many practical steps can significantly reduce risk or slow its progression. Prevention focuses on protecting joint health, reducing excessive stress on the hip, and maintaining strong, flexible muscles.

Maintain a healthy body weight: Excess body weight increases the load on the hip joint with every step.
Stay physically active: Regular, low-impact exercise helps maintain hip joint mobility and nourishes the cartilage.
Strengthen supporting muscles: Strong muscles around the hip, pelvis, and core help absorb forces that would otherwise stress the joint.
Improve flexibility and posture: Gentle stretching and mobility exercises help maintain a normal range of motion in the hip. Aggressive stretching past the point of pain can sometimes worsen things; however, it should be avoided.
Avoid joint overuse and repetitive strain: Repeated high-impact activities, heavy lifting with poor technique, or prolonged awkward positions can increase joint stress.
Prevent and manage injuries: Prompt and appropriate treatment of hip injuries reduces the risk of long-term joint damage.
Address childhood and structural hip conditions early: Conditions such as hip dysplasia or childhood hip disorders can increase the risk of early osteoarthritis if left untreated.
Manage work and lifestyle factors: Adjusting workstations, avoiding prolonged sitting, and incorporating movement into the day can reduce hip stiffness and strain.
Control other health conditions: Conditions such as diabetes and inflammatory disorders may affect joint health. Managing overall health supports better long-term outcomes for the joints.

Diagnosis of Hip Osteoarthritis

By the time patients see Dr Williams, many will already have a diagnosis of hip osteoarthritis, as it is commonly made by GPs or physiotherapists based on symptoms, clinical examination, and simple X-rays.

A clinical diagnosis is made by:

Taking a history of the symptoms. Commonly, patients describe an aching pain in the groin, front, side or back of the hip region, which is worse at the end of a long day of activity. Progressive stiffness may make daily activities like putting on shoes and socks or lifting the leg into a car more difficult. Sleep may also be affected by pain.
Performing a Medical Examination. Often, a subtle limp will be present, and hip rotation may be stiff and painful. Dr Williams will also seek to exclude other causes of similar pain, such as trochanteric bursitis or sciatica pain from the back.

Imaging Tests

To understand the nature of the condition. Imaging scans may be required:

X-rays are the most useful type of scan in the diagnosis of osteoarthritis. Dr Williams recommends a standing pelvic X-ray and a lateral (side-on) X-ray of the affected hip.

Common findings of hip osteoarthritis on X-ray include:

Joint space narrowing, meaning the gap between the ball and the socket becomes smaller as the cartilage thins.
Sclerosis or increased density of the bones around the hip joint.
Osteophytes are bone spurs that can form around the edge of the ball and socket, blocking the range of motion and sometimes causing sharp catching pain.
Subchondral cysts are pockets of fluid that can form in the bone below the cartilage in response to stress and fissures in the overlying cartilage.
MRI can be useful for diagnosing earlier stages of osteoarthritis or when the diagnosis is unclear. An MRI is not usually required for straightforward cases.

Treatment Options for Hip Osteoarthritis

Dr Williams sees many patients with varying degrees of arthritis, for whom surgery may or may not be the best treatment.

Hip osteoarthritis can be treated with various approaches, depending on the severity of the condition. The available treatment options include:

Lifestyle modifications: Losing weight, avoiding activities that worsen symptoms, and engaging in low-impact exercises, such as swimming or cycling, can help reduce pain and improve joint function.
Medications: Over-the-counter pain relievers, such as paracetamol or ibuprofen, can help relieve pain and inflammation. Prescription medications, such as longer-acting anti-inflammatories, may be prescribed for more severe cases.
Physical therapy: Exercises to improve joint flexibility, strength, and range of motion can be guided by a physiotherapist.
Injections: Corticosteroid injections or viscosupplementation injections may relieve pain and inflammation, at least temporarily. It is worth keeping in mind that total hip replacement should not normally be performed within 3 months of a corticosteroid injection due to a slightly increased risk of infection.
Surgery: When hip arthritis is significantly impacting quality of life and other non-operative measures have been exhausted, a total hip replacement is an excellent solution to relieve pain and restore function. Dr Williams prefers to use the minimally invasive direct anterior approach to hip replacement.

What if Hip Osteoarthritis is Untreated?

Many older people are living with untreated mild hip osteoarthritis. In some cases, hip osteoarthritis stays quite mild over the long term, with minimal impact on daily life. In other, more severe or progressive cases, untreated hip osteoarthritis can lead to significant joint damage, reduced mobility, and chronic pain. The joint damage may be irreversible, and the symptoms may worsen over time, leading to disability.

In severe cases, hip osteoarthritis can lead to secondary conditions, including back and knee pain.

What is Hip Osteoarthritis?