Hip joint osteoarthritis (OA), also known as hip arthrosis or coxarthrosis, is a degenerative joint disease. Symptoms of OA develop slowly over the years with the most common being hip joint pain, stiffness and difficulty walking. Hip OA is classified into two main categories:
- Primary or idiopathic osteoarthritis.
- Secondary osteoarthritis.
Primary osteoarthritis is caused by the physiologic aging process. Because of aging, the water content in the cartilages decreases, the proteins that make up the cartilage, such as collagen, slowly degenerate and overall the cartilage wears down. Due to aging the tissues also lose their ability to promptly and effectively repair. Over the years the erosion of the cartilage can also lead to deformities of the bone, such as growth of osteophytes. All of these changes overall contribute to the onset of inflammation of the joint, which leads to pain and movement limitations. In the most advanced cases there is no more cartilage as cushion between the bones of the joints. Primary osteoarthritis is typically found in people over 55 years of age and it is diagnosed once all causes of secondary OA have been ruled out.
Secondary osteoarthritis is caused by other conditions which in the end lead to the same results as primary OA: degeneration of the cartilage and bone, and onset of inflammation. Among the many causes of secondary OA there are:
- Obesity, as the increased weight carried by the patient increases the stress on the joint.
- Hip Dysplasia or other anatomical abnormalities, where the anatomical conformation of the joint causes increased stress on it.
- Gout, where the crystal deposits within the cartilage cause the degeneration.
- Rheumatoid Arthritis, where the inflammation caused by the disease leads to the degeneration of the joint.
- Diabetes and other hormonal disorders which can cause early degeneration of the cartilage.
Hip osteoarthritis is a very common disease all over the world; there is great variability among countries with a prevalence between 0,1-10% of the population depending on the country of reference: in the USA the prevalence is about 3-6% making it one of the most expensive conditions for the US healthcare, and the numbers are expected to grow worldwide in the future. Most of the people over 65 years of age develop radiographic evidence of osteoarthritis, but not all of them develop the symptoms and need treatment.
Symptoms of hip osteoarthritis (OA)
The most common symptom of hip osteoarthritis is joint pain which gets worse with repeated use of the affected joint and gets better with rest. Stiffness is another common symptom: it is usually worse in the morning after the joint has been inactive for the whole night and gets better after some movement. Other common symptoms are:
- Difficulty walking
- Crepitation of the joint
- Functional disability
- Balance issues
- Muscle weakness
Diagnosis of hip osteoarthritis
The diagnosis of hip osteoarthritis is made by the physician after reviewing the medical history, the symptoms reported by the patient and after performing a physical examination; the type, duration, and location of symptoms are the main indicators for the physician. A hip x-ray may help in the diagnosis by showing a narrowed joint space, loss of cartilage and bone spurs; it can also help in excluding other causes of hip pain and in assessing the need for surgery. However, in the early stages of osteoarthritis there might be no x-ray findings.
There is no blood test for hip osteoarthritis, although they can be prescribed to exclude secondary causes of OA such as rheumatoid arthritis.
An ultrasound-guided hip arthrocentesis, the aspiration of joint fluid, may sometimes be prescribed to exclude gout and infections.
Prevention, management and therapies for hip osteoarthritis
Symptomatic hip osteoarthritis affects 3-6% of the population, especially those over 55 years of age; asymptomatic hip OA, diagnosed with radiographic evidence of OA, is found in 15-20% of the population. Due to the high number of people who will develop OA in their lifetime, it is important to consider first the prevention strategies, which are also useful in stopping the condition from getting worse or at least in slowing its progression. When prevention fails or the condition progresses and becomes symptomatic there are 4 main treatment categories for the management of hip osteoarthritis:
- Physical Therapy
- Pharmacologic treatment using oral medications
- Pharmacologic treatment performing intra-articular joint injections
- Surgical therapy (hip arthroplasty)
Prevention of Hip Osteoarthritis
The 3 main ways of preventing hip OA are the following:
- Maintain a healthy weight or lose weight if overweight/obese. Carrying extra kilos can increase the risk of developing OA by up to 5 times due to the increased stress on the joints.
- Exercise. Muscles support the joints; having weak muscles increases the stress on the joints. 150 minutes of moderate intensity aerobic activity per week are recommended for all adults. Older adults should try to stay active most days, even just walking 30 minutes every day will help in maintaining and improving physical strength.
- Avoid injuries or get them treated. Wear the proper shoes, maintain good posture, warm-up before exercising, avoid subjecting your joints to excessive stress, … these are all ways of preventing injuries. If you get injured, seek medical treatment promptly: ignoring an injury can lead to further damage to the joint. Taking the appropriate prescribed rest or using the prescribed crutch for example can mitigate the risk of further damage.
Physical Therapy for hip osteoarthritis
Once symptoms of hip OA develop it is better to seek support from a physical therapist. Unsupervised exercise can worsen the condition. A physical therapist will help in maintain the correct form, posture, train the right muscles, assess the gait, and train not only the strength, but also the balance. PTs will be able to advise on how to unload the joint by using a cane or crutch to mitigate the inflammation and pain. They will assist in designing an exercise program tailor made to the needs of each specific patient. Moreover, by being supervised during your time exercising, you will be more likely to stick to the training routine, instead of skipping it due to discomfort and lack of motivation.
Oral medications for hip OA
There are several medications available to treat the symptoms associated with hip osteoarthrosis. Among the medications that only target pain, the main one used is acetaminophen with a maximum daily dose of 4,000mg if no liver disease in medical history, maximum single dose of 1,000mg and minimum interval between doses of 4 hours. Other pain medications used to relieve OA pain are tramadol, codeine and opioids such as oxycodone and hydrocodone, which need a prescription and are addictive. For the choice and dosage of the drug, it is advised to ask your physician and have him decide the treatment plan for you.
Other commonly recommended medications for osteoarthritis are NSAIDs or nonsteroidal anti-inflammatory drugs; they relieve pain and target inflammation too. Some of these medications are available OTC, while other require a prescription. Among the many there are ibuprofen, aspirin, naproxen, diclofenac and celecoxib. This class of medications can cause damage to the stomach and can interact with other conditions or medications, so again it is better to seek the advice of your GP beforehand.
Oral corticosteroids, such as prednisone and cortisone, are usually not prescribed nor recommended for hip OA.
Separate category is the one about supplements for the treatment of osteoarthrosis. There are not many studies supporting their use and they might have no effect at all both on symptoms and on disease progression, although anecdotal evidence suggests their effectiveness. Among the many there are:
- Glucosamine sulfate
- Chondroitin sulfate
- MSM or Methyl-Sulfonyl-Methane
They are often found combined in a product and not as single agent. Their efficacy has still to be proven on large scale double-blind studies.
Intra-articular joint injections for the treatment of hip osteoarthrosis (OA)
As of today, there are several different types of intra-articular joint injections for the treatment of osteoarthrosis. They target both pain and inflammation in the long term as opposed to the short-term effect of oral medications, and, in some cases, they claim to aid with the regeneration of lost cartilage.
Here are the main agents injected for this type of therapy:
- Hyaluronic Acid (HA) or Sodium Hyaluronate. HA is naturally present in the joints as one of the many constituents of the cushion between the bones as well as in the fluid that lubricates the joint. In osteoarthritis there is a reduction in the HA content within the joint. Several hyaluronic acid injections performed 1 week apart can help relieving pain and reducing inflammation. Effectiveness is controversial and varies greatly among individuals; in general, improvements are seen after a couple of weeks from the beginning of the treatment and last up to 6 months.
- Corticosteroid injections. Steroids are commonly injected within the joints to reduce pain and inflammation. Their advantage is that they act very quick but can’t be performed more than 3-4 times in the same joint within a 12-18 months period as they otherwise accelerate the joint degeneration.
- PRP or Platelet Rich Plasma. This novel therapy is gaining fame and is being applied in many different medical specialties. It is a substance derived from the whole blood of the patient, which is drawn and centrifuged to separate its components. There is not much evidence yet and its effectiveness is controversial, but it seems to be more effective than hyaluronic acid in reducing pain and inflammation.
- Mesenchymal Stem Cells. Stem cells are another promising and safe novel therapy currently under investigation in several clinical trials across the world. They are usually obtained from the fat tissue or from the bone marrow of the patient. Early data and small-scale studies show decrease in pain and inflammation and possibly regeneration of the lost cartilage, but further long-term studies are needed to evaluate its effectiveness.
Surgical therapy: hip arthroplasty
Surgical therapy, known as hip arthroplasty or joint replacement surgery, is generally recommended when all conservative treatments fail or when hip osteoarthritis is too advanced and causing excessive pain and functional limitation to the patient. The age of the patient is also an important factor when choosing whether or not to operate.
The goal of the surgery is to relieve pain and to restore the function of the hip and we will talk more in detail about this therapy in this dedicated article on hip arthroplasty.
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