Hip

Anatomy

The hip is a ball-and-socket joint. The socket is formed by the acetabulum, which is part of the large pelvis bone. The ball is the femoral head, which is the upper end of the femur (thighbone).

A slippery tissue called articular cartilage covers the surface of the ball and the socket. It creates a smooth, frictionless surface that helps the bones glide easily across each other. It is degeneration, or wear and tear, of this “articular cartilge” that causes “Osteoarthritis”.

The acetabulum is surrounded by a strong fibrocartilage, rubber like, ring called the labrum. The labrum forms a gasket around the socket, helping to improve its stability.

The joint is surrounded by bands of tissue called ligaments. They form a capsule that holds the joint together. The undersurface of the capsule is lined by a thin membrane called the synovium. It produces synovial fluid that lubricates the hip joint.

Arthritis

Common causes of joint damage

The most common cause of chronic hip pain and disability is osteoarthritis. Other forms of arthritis include inflammatory arthritis like rheumatoid and post traumatic arthritis.

• Osteoarthritis
  This is an age-related “wear and tear” phenomenon. Its incidence increases with age, and is most common in people older than 55 years of age. The articular cartilage (slippery lining) of the bones of the hip wears away. The bones then rub against each other, causing hip pain and stiffness.

• Rheumatoid arthritis
  This is much less common (1% of population). It is an autoimmune disease in which the bodies own immune system is over active and attacks various tissues including synovium (joint lining) and cartilage. This chronic inflammation leads to irreversible cartilage damage, resulting in pain and stiffness. It can effect any joint, but has a prediliction for the hands and wrists. Rheumatoid arthritis is the most common type of a group of disorders termed “inflammatory arthritis.”

• Post-traumatic arthritis
  This can follow a serious hip injury or fracture, which damages the articular cartilage or the blood supply to the ball (femoral head)

• Avascular necrosis (AVN)
  This literally means “death of bone due to lack of blood”. The commonest causes of AVN in our community are trauma (hip dislocations or neck of femur fractures), excessive alcohol use, steroid use (prednisolone etc) and “idiopathic”- a medical term for “cause unknown”. Other less common causes are deep sea diving (decompression sickness), sickle cell anaemia, infections, and some genetic conditions.

• Childhood hip disease
  Some infants and children have developmental hip problems, whereby the socket (acetabulum) doesn’t form properly. This can cause the hip to become unstable and even to dislocate. This can lead to arthritis later in life, often at an earlier than normal age. This happens because the hip may not grow normally, which can result in a mismatch between the congruence or “roundness” of the corresponding surfaces of the ball and socket.

Hip replacement

First performed around the1960’s, hip replacement surgery is one of the most successful operations in all of medicine. Since its inception, improvements in  surgical techniques and implant technology have greatly increased the effectiveness of total hip replacement.

In a total hip replacement the damaged ball and socket are removed and replaced with prosthetic components.

• The damaged femoral head is removed and replaced with a metal stem (made of Titanium or Stainless Steel) that is placed into the hollow center of the femur (thigh bone). The femoral stem may be either cemented or “press fit” into the bone.
• A metal or ceramic ball is placed on the upper part of the stem. This ball replaces the damaged femoral head that was removed.
• The damaged cartilage surface of the socket (acetabulum) is removed and replaced with a metal socket. Screws may be used to assist with fixation of the socket to the pelvis.

A very advanced hard wearing plastic (Cross linked Ultra High Molecular Weight Polyethylene) or ceramic spacer is inserted between the new ball and the socket to allow for a smooth gliding surface.

Dr Gomez does NOT use, and has never used, Metal on Metal bearing surfaces or any type of Metal on Metal prosthesis- including the “ASR”. He routinely uses ceramic on polyethylene.

Candidates for Surgery

There are no absolute age or weight restrictions for total hip replacements.

The decision to have surgery is your decision and will made in cooperation with Dr Gomez who will provide you with all the information you require to make a balanced and informed decision.

When Surgery Is Recommended

Hip replacement surgery is aimed predominantly at pain relief. By providing patients with a painfree hip, their function and quality of life are usually then vastly improved. As such I see the major indications for hip replacement as

• Pain causing functional impairment
• Pain that compromises quality of life
• Night and rest pain, especially that which disturbs sleep
• Pain that no longer responds to pain killer’s
• All other non operative treatment modalities have been exhausted.

Before surgery

Dr Gomez will take a comprehensive history regarding your

• Hip problem
• Past medical history
• Current Medications and Allergies
• Previous anaesthetics and operations

Your hip will be thoroughly examined and X-rays, or other imaging, will be performed to assist in the diagnosis, and also in the planning of the surgery

Blood and urine tests will also be performed

This is to ensure the surgery is planned and conducted in the most effective, and safest, possible manner.

Your Surgery

You will usually be admitted to hospital on the day of your operation.

It is essential that you have fasted (nothing past your lips – food or fluid) for 6 hours prior to surgery. An exception is the taking of your usual medications (especially heart, blood pressure and reflux tablets) with a small sip of water. Blood thinning medications will be stopped 5-7 days before surgery.

Your anaesthetist will meet you on the day to discuss the most appropriate, and safest, method of anaesthesia and pain management for your operation and post operative period. This is usual a spinal (numb from the waist down) or general (asleep) anasethetic. They will be happy to discuss any questions you may have at this time.

The procedure takes approximately 90 minutes.

You will wake up in the recovery room where you are monitored closely by nursing staff in the initial phases of the post operative period before returning to the ward.

Post Surgery

On the first post operative day you will have a blood test and get Xrays of your brand new hip. Nursing staff will ensure you receive adequate pain relief to make you as comfortable as possible.

You are able to get up and bear full weight on your operative limb and will begin physiotherapy and mobilizing straight away.

You will usually return home between 2-5 days post surgery, with a physiotherapy program to perform at home.

Exercise is a critical component of your rehabilitation after leaving hospital. You should be able to resume most normal light activities of daily living within 3 to 6 weeks following surgery. Some discomfort with activity and at night is common for several weeks.

Your activity program should include:

• A graduated walking program to slowly increase your mobility, initially in your home and later outside
• Resuming other normal household activities, such as sitting, standing, and climbing stairs

Specific exercises several times a day to restore movement and strengthen your hip. You will be given exercises to perform at home by our physiotherapists, who will supervise your progress over the first few weeks.

Dr Gomez will see you daily whilst in hospital, then in his rooms at the 2 week post operative mark to check the healing of your wound. Please do not hesitate to contact his rooms at any time should you have any concerns about your progress.

Hip Arthroscopy

Arthroscopy is a surgical procedure that allows Dr Gomez to look inside your hip joint with a small camera (“arthroscope”). This helps to both diagnose and treat problems within the joint in a minimally invasive “key hole” manner.

During hip arthroscopy a small fibreoptic camera, called an arthroscope, is inserted into your hip joint through a 1.5cm incision. The camera displays pictures on a television screen, and Dr Gomez uses these images to guide miniature surgical instruments within the hip, inserted through an additional small 1.5cm incision.

Hip arthroscopy has been performed for many years, but is not as common as knee or shoulder arthroscopy.

Hip arthroscopy may relieve the painful symptoms of many problems that damage the labrum, articular cartilage, or other soft tissues surrounding the joint. Although this damage can result from an injury, other orthopaedic conditions can lead to these problems, such as:

• Femoroacetabular impingement (FAI) is a disorder where bone spurs (bone overgrowth) around the socket or the femoral head cause damage by abutting against each other
• Dysplasia is a condition where the socket is abnormally shallow and makes the labrum more susceptible to tearing.
• Snapping hip syndromes cause a tendon to rub across the outside of the joint. This type of snapping or popping is often harmless and does not need treatment. In some cases, however, the tendon is damaged from the repeated rubbing.
• Bursitis inflammation of a potential sac between two soft tissue structures
• Loose bodies, such as fragments of bone or cartilage that have detached and move around within the joint.
• Hip joint infection

Revision Total Hip Replacement

Total Hip Replacements (THR) can be expected to last around 20 years in approximately 95% of patients.

However, there are occasions whereby either part, or all, of the components of a THR may require replacement. This can range from a minor exchange of a liner or head, to a major replacement of all components with reconstruction of lost bone stock.

Indications for revision THR include:

• Plastic (polyethylene) wear – may involve changing liner alone
• Loose components – Femoral, Acetabular (socket) or both
• Infection – In an effort to eradicate a hard to treat infection, or if it has caused the components to loosen
• Dislocation – To realign the components or provide additional stability to the hip joint
• Osteolysis (bone loss) – to reconstruct bone defects
• Fracture – especially those that cause the components to become loose.

Diagnosing a failed implant

Joint replacement surgery has been shown to decrease pain and increase function in the vast majority of patients. Once a patient progresses through the postoperative period, symptoms of pain, as well as the stability and motion of the joint, should remain stable for an extended period of time.

Indicators that a joint replacement may be failing include an increase in pain, a change in the position of the implant(s), or a decrease in the function of the patient. Patients who demonstrate these symptoms and signs may require revision joint surgery. A standard, and comprehensive, assessment is performed to work out the reason for failure. This includes a thorough history and physical examination, X-rays and other imaging, blood tests, and possibly aspiration (using a needle to sample joint fluid).

History and Physical Examination

The history and physical examination will identify patients who have a change in their pain level. Also, information can be obtained regarding activity levels and use of assistive devices, such as crutches or a walking stick. Mechanical failure or infection may also present with redness and warmth of the affected joint. A limp or deformity may be identified.

X-Rays

X-rays taken of the area around the joint replacement yield important clues regarding stability of the implant. Failure due to the most common cause, aseptic (non infected) loosening, can be identified by several findings. For example, the implant may have moved, compared to previous X-rays, or there may be a lucent (visible) line between the component and the cement or bone, signifying that the bond between the bone and implant has degraded. Areas of bone loss (osteolysis) can be identified. Mechanical failure with broken implants or severe wear is also assessed by comparison to previous X-rays. For these reasons, serial follow-up radiographs are recommended to catch joint failure at an early stage.

Laboratory Tests

Common blood tests for possible failed joints include a Full Blood Examination (FBE), an erythrocyte sedimentation rate (ESR), and a C-reactive protein test (CRP). These tests are most helpful in the detection of infected joint replacements. A combination of normal tests is very reliable at ruling out infection. Abnormal tests require further investigations.

Additional Tests

Joint fluid may be removed with a needle and analysed, a technique called aspiration, to assist in the diagnosis of possible infection. If positive for infection it may also identify the causative organism allowing targeted therapy. Dr Gomez usually performs this in the operating theatre to ensure adequate sterility. In addition, bone scan studies that use short-acting radioactive isotopes may be used. Bone scans detect abnormal bone activity and increased bone turnover, which may be present in infection, fracture, or prosthetic loosening. Other types of bone scans can also be performed which help to differentiate more accurately between infection and aseptic (non-infected) loosening.