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Expert opinion

Mako robot-assisted total hip replacement

Modern hip replacement surgery was pioneered by Sir John Charnley in the UK in the early 1960s. The procedure and implant used were developed and refined over the next 30…

Sarah reaches Everest Base Camp after hip surgery

Total hip replacement surgery is one of the most successful, cost-effective and safest operations in the world today. However, despite its overall success rate, hip replacement surgery is a major…

One of the most successful operations of the 20th century

With around 80,000 carried out each year, hip replacements are one of the most common elective surgical procedures in Britain. We speak to 41-year-old Rhys Gwilliam who managed 16 years…

Specialist Hip Unit

Hip replacements are one of the most common elective surgical procedures in Britain. We speak with the team behind the new dedicated Hip Unit at Circle Bath hospital to find…

A patient’s perspective

Hip problems can arise at any time in life. Choosing to have surgery can be a life changing experience, however understanding the procedure and rehabilitation helps for a speedier recovery.

Conditions & Treatments

We offer the full range of treatments for hip conditions using the latest techniques and pioneering surgeries

To read more about these treatments, please scroll down this page.

 

What is the hip joint?

The hip is a ‘ball and socket’ joint at the top of the leg, which is the junction between the spine and pelvis with the mobile lower limb. The hip has a very good range of movement allowing not only normal day to day activities such as walking and climbing stairs but also the participation in competitive sport.

The medical term for the ‘ball’ is the femoral head whereas the ‘socket’ is called the acetabulum and describes a hollow in the pelvic bone.

Generally speaking, despite its very good range of movement, the natural hip joint is very stable and rarely dislocates i.e. comes out of joint. This is partly due to the shape of the hip but there is a contribution from a sealant around the periphery (outside) of the acetabulum called the acetabular labrum. The labrum, along with the capsule that surrounds the joint, allows synovial fluid within the joint to lubricate and nourish the articular cartilage, which lines the surface of both the femoral head and acetabulum.

Conditions

Hip Pain

This can be due to a soft tissue ‘strain’, the symptoms of which settle fairly quickly, or become more chronic (i.e. long term) due to a variety of conditions.

Hip pain is most commonly experienced in the groin, down the front of the thigh to the knee (innervated by the obturator nerve) but also over the outer aspect of the hip or in the buttock region. Occasionally, pain in the knee may be the only site of pain arising from the hip (so called ‘referred pain’). Problems in the low back (lumbar spine) can cause pain to be felt in the hip region.

In addition to pain patients often notice a restricted range of movement. This can make reaching the foot to tie shoe laces or cut toe nails difficult. Sexual intercourse may become awkward for female patients.

Due to a combination of pain and stiffness or weakened muscles a limp may develop.

The combination of these factors results over time in a loss of function, which can affect patients in many different ways.

Hip Arthritis

Whatever the underlying cause hip arthritis develops when the cartilage lining of the joint wears away resulting in the bone of the pelvis (‘socket’ of the joint) rubbing against the bone of the femoral head (‘ball’ of the joint) leading to destruction of the hip joint. Once this process starts it continues to progress although the rate of progression and the symptoms that its causes varies from patient to patient.

In studies carried out by ‘Arthritis Research UK’ it has been shown that 33% of the population over 45 years have sought treatment for symptomatic osteoarthritis. After the knee the hip is the second most commonly affected joint.

Hip arthritis affects 11% of the UK population older than 45 years. Severe hip arthritis affects 3% of the population over 45 years. It is more common in women than men (12% women and 7% men aged over 75 years).

10% – 15% of patients present with ‘mixed symptoms’ arising from the lumbar spine and hip.

Treatment has two major objectives – relieve pain and preserve function.

Conservative (non-surgical) treatment involves activity-modification, physiotherapy (to help maintain range of movement and optimise muscle function), anti-inflammatory medication and weight loss (if indicated).

‘Nutraceuticals’ such a glucosamine and chondroitin supplements can help some patients but there is little scientific evidence that these work.

Developmental dysplasia of the hip

This condition affects babies and very young children.

The hip is ‘out of joint’ and diagnosed immediately after birth or over the next 12-18 months often due to delay in walking. Paediatric surgeons aim to ‘contain’ the hip keeping the femoral head (i.e. ball) within the acetabulum (i.e. socket). This often requires surgery.

With the introduction of ultrasound screening of the hip in babies and active treatment with the aim of allowing the hip to develop naturally, the more severe cases presenting in later adult life are now rarely seen in the U.K.

Surgical reconstruction by hip replacement can be complex and associated with specific risks. A full discussion or risks versus benefits of hip replacement is required.

Legg-Calvé- Perthes disease

This is a condition where the blood supply to the femoral head (i.e. ball of the hip joint) is adversely affected. The condition is most common in boys aged 4 to 12 years old.

The condition is treated by paediatric orthopaedic surgeons but in more severe cases, due to subsequent deformity of the femoral head (and acetabulum), which results in pain, functional stiffness and leg length discrepancy, patients present later to specialist hip replacement surgeons to consider surgery.

The average age when hip replacement is performed in such patients is in their late 30s so a discussion about types of hip replacement, bearing options and implant longevity is required

Slipped Upper Femoral Epiphysis

A condition affecting both boys and girls usually around 12-13 years of age at the time of the adolescent growth spurt where the femoral head (i.e. ball of the joint) ‘slips’ relative to the femoral neck.

Patients present with groin, thigh or often knee pain. Surgery to stabilize or re-align the femoral head is required. Patients often present in later years (but when still relatively young) to specialist hip surgeons.

Metal work removal and further imaging is required. Some patients will require hip replacement surgery due to a combination of pain, functional hip stiffness and leg length discrepancy resulting in a limp. A discussion about types of hip replacement, bearing options and implant longevity is required.

Femoro-acetabular impingement (FAI)

This condition has come to dominate young and middle-aged adult hip practice over the past decade or so. First described by Carlioz in France (1968) and then identified and brought to main stream attention by Ganz in Switzerland (2003).

Due to deformity of the upper femur or acetabulum Ganz described a “repeated abnormal contact between the area of the head/neck of the femur and acetabular rim, resulting in damage to the labrum and cartilage”.

The condition causes hip pain in young adults and is recognized as cause of early hip arthritis.

Whilst ‘hip impingement’ may be caused by one of the adolescent hip problems such as Perthes’ disease or slipped upper femoral epiphysis the majority of patients with hip symptoms attributed to FAI have no identifiable cause.

Stresses on the femoral head growth plate in adolescent, resulting in a degree of deformity, has been suggested as a cause of FAI developing. The abnormality may be on the femoral side – ‘cam’ deformity – on the acetabular side – ‘pincer’ deformity – or a combination – ‘mixed’ deformity.

Investigations required include plain x-rays, MRI scans (sometimes with contrast injected into the hip – an arthrogram) or 3D CT scans. The MRI is primarily for assessment of the soft tissues and bone. 3D CT scans provide an excellent image of the shape of the femoral head and neck and help plan surgical intervention.

Treatment can be non-surgical such as activity modification, physiotherapy and injections. Surgical treatment in the first decade of the 21st century required ‘open surgical dislocation’ of the hip with a protracted recovery period.

Over the past decade hip arthroscopy has developed to a stage that most problems on the femoral side of the joint can be treated with ‘keyhole’ surgery. Acetabular problems may require open surgery to re-align the acetabulum the so called ‘peri-acetabular osteotomy’. First described by Ganz in 1988 Søballe (in Denmark) developed in 2003 a percutaneous minimally invasive technique to reduce the soft tissue trauma of this major procedure and enhance the recovery rehabilitation process.

It is too soon to prove that these surgical interventions for patients with FAI prevent or delay the onset of symptomatic hip arthritis.

Avascular necrosis (AVN) / Osteonecrosis of the hip

This condition is caused by death of the cells that make bone. It is thought to be due primarily due to a localised abnormality of clotting (or ‘coagulation’). This leads to collapse of the surface of the femoral head (i.e. the ball of the joint) and eventually will cause degenerative arthritic change.

Whilst AVN can occur in all ages it is most common in 40-65 year olds and in men rather than women. It causes a dull ache or throb in the groin or buttock. Patients may develop a limp. Whilst in most patients no particular cause can be identified (so-called ‘idiopathic AVN’) in the U.K. common causes include steroid use or a high alcohol intake.

Previous hip trauma can cause AVN. There are many other ‘textbook’ causes of AVN but these are relatively rare. Sickle cell disease in the black population is one of the less common causes. The condition can affect both hips (i.e. be bilateral) in up to 50% of patients.

How far the condition has progressed is described by the Ficat Classification. This helps to plan treatment. Non-surgical options include anti-inflammatory medication for pain. Protected weight bearing with crutches and physiotherapy/hydrotherapy to keep the hip mobile.

Surgical options include core decompression to encourage healing of the dead bone. Hernigou (in France) first described ‘bone marrow transplantation’ in 1993, which is undertaken at the same time as the core decompression and has shown that in early AVN (Ficat Stage 1-2) the risk of requiring hip replacement at 5 years is reduced.

The results in more advanced cases were less successful. Attempts to bring blood flow into the dead femoral head (e.g. vascularized free fibular graft) has been described. This is no rarely indicated. Bony re-alignment operations (i.e. ‘osteotomies’) have been described particularly in the Far East where AVN is more common. They are rarely used in the U.K.

AVN as the cause for surgery accounts for around 5% of hip replacements. Historically the outcome of hip replacements in patients with AVN has been less successful than in patients having surgery for hip arthritis. This will be due to the fact that the AVN patients tend to be younger and more active.

With modern implants and bearing options patients with AVN can look forward to excellent symptoms relief although the National Joint Registry has shown that in patients who undergo hip replacement surgery aged less than 55 do have an increased risk of require a revision (i.e. ‘re-do’) operation

Septic arthritis

Infection of a native hip joint in adults is uncommon but a recognised cause of degenerative change.

The initial treatment is aimed at identifying the causative organism and eradicating the infection.

This will usually require at least one operation, to drain pus from the hip joint, followed by a prolonged course of antibiotics. Despite this aggressive management damage to the articular cartilage of the hip joint can lead to arthritic symptoms requiring a hip replacement.

Primary and metastatic tumours

Tumours related to the hip can be benign or malignant. Primary bone tumours (i.e. arising from the bone itself) affecting bones are rare. Benign bone tumours include osteoid osteoma, which can cause patients to present with pain in the hip region.

Osteochondroma is the most common primary bone tumour and can be single or multiple. If theses swellings cause pressure symptoms or restrict range of movement they may require removal. Giant cell tumours are benign but behave more aggressively and are referred to the regional bone tumour unit, which for Bath in at the Nuffield Orthopaedic Centre in Oxford. Other benign tumours that can affect the hip include synovial osteochromatosis and pigmented villo-nodular synovitis.

Metastatic bone tumours are much more common and often affect the pelvis and hip joint. Metastatic tumours are spread of tumour from somewhere else and most commonly are from the lung, breast, prostate, kidney and thyroid with the first three being by far the most common.

Metastatic tumours cause pain but a common form of presentation is following a fracture. A so-called ‘pathological fracture’. The patient may be unaware that they have cancer before the development of a pathological fracture.

Initial management is to stage the tumour (i.e. to determine who widespread the cancer is) requiring a wholebody bone scan, CT scan of the chest and abdomen, a CT and MRI of the affected area. Treatment is initially surgical either by fixing the fracture or doing a joint replacement followed by radiotherapy and chemotherapy (as indicated).

Soft tissue disorders

These can be intra-articular soft tissue disorders (i.e. within the hip joint) or extra-articular soft tissue disorders (i.e. arising outside the hip joint). Intra-articular disorders include acetabular labrum tears, abnormalities of the synovium including synovitis, pigmented villo-nodular synovitis and synovial chondromatosis.

Extra-articular soft tissue disorders include bursitis (most commonly ‘trochanteric bursitis’ a cause of outer lateral hip pain and ‘psoas bursitis’ a cause of groin pain). Inflammation or degeneration of the tendons around the hip, in particular, the abductor tendons, is a cause of pain and weakness leading often to a noticeable limp.

Tendon can cause problems by abnormal rubbing as they from the bones of the hip and pelvis. These include the iliotibial band (laterally) and iliopsoas psoas tendon (in the groin). These conditions are initially treated with physiotherapy techniques but if persist surgery may be required.

Full Range of Hip Treatments

We offer the full range of treatments for hip conditions using the latest techniques and pioneering surgeries. Scroll down to see all the Surgical and Non-sergical treatments we offer.

Non-surgical treatments

Self-Treatment

If your hip pain doesn’t improve with simple medications such as paracetamol and ibuprofen, you should see your doctor for further advice.

Reducing the strain (sitting posture, avoid carrying heavy weights, walking stick) and weight loss will help.

Specialist Physiotherapy

A physiotherapist can also suggest specific exercises to maintain or improve the strength of the muscles around the hip joint. They may advise you about the best way to walk with your hip pain and may help you to use a stick or crutch.

You’ll need to use the stick in the opposite hand to your affected hip and make sure that it’s the correct height for you, so it’s important to see a physiotherapist before you start using one.

Patients may find helpful the 2015 second edition of Dr Robert Klapper’s book “Heal Your Hips: How to Prevent Hip Surgery – and What to Do If You Need It”. Dr Klapper is an orthopedic surgeon based on Los Angeles and a well-respected educator.

This book is a comprehensive guide to hip health co-written with Lynda Huey a former sprinter and now a track coach at UCLA working with professional athletes. It can be purchased online through Amazon UK.

Steroid injections

Steroid injections can help hip problems if they’re caused by inflammatory joint pain or inflamed bursae.

The injections are often given with a local anaesthetic, and they’re usually very helpful in treating trochanteric bursitis.

Surgical Procedures

Hip Joint Injection

Patients describe ‘hip’ symptoms, which can cover the groin, buttock, upper thigh (front and side) as well as the iliac crest – the bony part of the outer pelvic bone.

Pain experienced in these areas can in fact arise from the hip joint, from ‘around the back’ (lumbo-sacral spine or sacro-iliac joints), from ‘around the front’ (symphysis pubis) of from the soft tissues (trochanteric bursitis / abductor muscles) or even from an inguinal hernia.

The source of the symptoms is usually determined by the history, examination and simple investigations such as radiographs (X-rays) but in some patients an anaesthetic hip injection (‘hip block’) can be very helpful. In a third of patients with hip arthritis found at arthroscopy the routine X-rays were normal.

Hip injections can be ‘diagnostic’ (is the hip joint the source of the pain?) and /or ‘therapeutic’ (administered with the aim to improve symptoms).

Hip injections are performed as a day case using local anaesthetic in the operating theatre, to reduce the risk of infection, under X-ray (image intensification) control. There are two types of injection. The first simply contains long acting local anaesthetic. Any symptoms arising from the hip joint will be ‘blocked’ for a few hours. The second, in patients suspected to have hip arthritis, the injection will contain a steroid (such as depomedrone) in addition to the long acting local anaesthetic.

All patients are contacted 4-6 hours after the injection to review any change in their symptoms.

For those patients who have steroid added to the injection, in addition to long acting local anaesthetic, are reviewed in clinic 4 weeks after the injection to assess for the response to the steroid.

Around 75% of patients respond positively to the injection. Around 25% of patients report no change in their symptoms after the hip injection. These patients go on to further investigations and around 80% benefit from treatment for an alternative diagnosis. 10% of patients report no initial response to the local anaesthetic but then go on to benefit from the steroid.

Hip injections are reported to have:

100% specificity (probability of a patient who does not have the condition testing negative).
100% positive predictive value (probability of a patient who tests positive having the disease).
90% sensitivity (probability of the patient with the condition testing positive)
85% negative predictive value (probability of a patient testing negative not having the disease).

Recent evidence from Harvard University (2016) has shown an increased risk of peri-prosthetic (deep) infection after hip replacement in patients who have had ‘multiple’ hip joint steroid injections (2 or more the year before the hip replacement). The risk was increased from 2% to 6.6%. In this series the hip injections were performed in the radiology department rather than in the operating theatre. To reduce the risk of infection as much as possible Mr Burwell undertakes hip injections personally in the operating theatre.

It is for this reason that repeated steroid injections is not considered a sensible way to manage patients with symptomatic hip arthritis.

If patients proceed to having a hip replacement it is recommended that the hip replacement is not performed until at least 3 months after the last steroid hip injection to reduce the risk of peri-prosthetic joint infection. In a recent American review of 35,000 patients undergoing a hip replacement there was no increased risk of peri-prosthetic joint infection in those patients who had undergone a steroid hip injection more than 3 months before their hip replacement (Werner et al, 2016).

Risks of having a steroid injection to the hip include acute infection (septic arthritis), an increased risk of infection after a subsequent hip replacement (peri-prosthetic joint infection) and damage to the lining of the hip joint (articular cartilage). Some patients report numbness in the front of the thigh to the knee and very rarely weakness in lifting the leg up for a few hours after the injection. This is due to the local anaesthetic placed into the skin and soft tissue prior to the steroid injection itself. These symptoms wear off within a couple of hours.

Hyaluronic Acid (HA) and Platelet-Rich Plasma (PRP) Hip Injections

Hyaluronic acid (HA) – this is the main chemical component found in synovial joint fluid. The normal high viscosity of HA is reduced in patients with hip arthritis. HA injections act mainly as a ‘visco-supplement’ but may have some ‘bio-supplement’ properties reducing inflammation and pain. Formulations with higher concentration of HA require fewer injections. Symptom improvement usually is evident by 3 months. Those patients with ‘early arthritis’ generally do better. Age does not appear to have any influence.

Platelet-Rich Plasma (PRP) – this is made by centrifuging the patient’s own blood plasma to increase the concentration of platelets. PRP injections act by delivering a large pool of ‘signaling/regulatory proteins’ (growth factors, cytokines etc.) encouraging tissue regeneration / intrinsic repair mechanisms. There have only been a limited number of clinical studies to date.
Arthritis is graded on X-rays by the Tonnis classification:
0 No signs of osteoarthritis
1 Mild: Increased sclerosis, slight narrowing of the joint space, no or slight loss of head sphericity
2 Moderate: Small cysts, moderate narrowing of the joint space, moderate loss of head sphericity
3 Severe: Large cysts, severe narrowing or obliteration of the joint space, severe deformity of the head

A Spanish study (2011) with 70% of patients having OA Tonnis grade 3 reported that after 3 PRP injections at weekly intervals almost 60% of patients reported ‘clinically relevant relief of pain’ at 6 months with 40% rated as ‘excellent responders’ with early pain reduction at 6 weeks maintained at 6 months. Treatment was not effective in 25% of patients.

Patients recruited into most studies have had ‘intermediate’ arthritis using the Kellgren Lawrence classification of arthritis (although this classification was developed for the knee)
0 = No radiographic features of OA
1 = Doubtful joint space narrowing and possible osteophytic lipping
2= definite osteophytes and possible joint space narrowing on AP WB radiographs
3= multiple osteophytes, definite joint space narrowing, sclerosis, possible bony deformity
4= Large osteophytes, marked joint space narrowing, severe sclerosis and definite bony deformity.
Established arthritis is K-L grade 2 or higher

To date in the UK injections for patients with symptomatic arthritis of the hip have mainly used a steroid (e.g. Depomedrone). More recent alternative options include HA and PRP. Whilst basic science research supports their potential benefits this has yet to be proven in careful clinical trials. As a course of injections is required there is the concern that there might be an increase in the risk of peri-prosthetic infection following a subsequent hip replacement.

A trial in Belgium (101 patients) compared HA injection, steroid injection and placebo injection. This showed ‘limited’ benefit of steroid and HA in relieving pain in the short term without any positive long term effects. A placebo injection (i.e. normal saline) resulted in 30% pain reduction and this must be kept in mind when comparing with other types of injection.

Comparison of HA to PRP is lacking. One study (2012) suggested no difference at 3 months but improved outcome at 12 months after PRP injections.

It has been suggested that HA and PRP injections be combined – there have been positive outcomes in patients with healing of pressure ulcers and surgical wounds – but there is no data on this combination following hip injections to date.

Hip Arthroscopy

Arthroscopy (“key hole”) surgery is possible with all the major joints in the body. Surgeons first started arthroscopy to the hip joint back in the 1970s but it wasn’t really until the early 2000s that the development of traction tables (to distract the hip joint) and newer instruments to facilitate the procedure that it became more main stream. The number of hip arthroscopy procedures is increasing year on year and its role, in the management of various hip disorders, is becoming more focused.

Hip arthroscopy has been used for procedures both within the hip joint (intra-articular) and in the soft tissues surrounding the hip joint (extra-articular). Intra-articular procedures are carried out for conditions such as femoro-acetabular impingement, labral tears, removal of loose bodies, the diagnosis and treatment of infection (septic arthritis). Extra-articular procedures have been described for patients diagnosed with greater trochanter pain syndrome / ‘trochanteric bursitis’ and ilio-tibial band syndrome (‘snapping hip’).

The most experienced hip arthroscopic surgeon in the UK is Mr Richard Villar who has trained most of the surgeons in this country either as Fellows or through his Hip Arthroscopy Courses. Mr Burwell has completed Mr Villar’s hip arthroscopy course and operated with him in London and Bath. However, in 2007 Mr Burwell decided to concentrate his practice on joint replacement. Despite this, up to third of Mr Burwell’s out patient practice involves the assessment of younger patients with hip symptoms. Most of these can be managed without surgery but some patients are appropriate for arthroscopic hip procedures. Mr Burwell ensures that he keeps ‘up to date’ with the developments in hip arthroscopy and hip preservation surgery and therefore can offer patients an ‘unbiased opinion’ of what is available to them and which surgeon they should be referred to.

 

Hip Resurfacing

Hip resurfacing is a bone sparing procedure (particularly on the femoral side of the hip joint where the superficial part of the ball of the joint is replaced with a metal cap) and in Mr Burwell’s practice is still considered in appropriate patients requiring hip replacement surgery.

2017 marked the 20th anniversary of the introduction of ‘modern hip resurfacing’ by Mr Derek McMinn with the Birmingham Hip Resurfacing. This implant that has the best outcome results for hip resurfacing in the National Joint Registry (NJR).

Mr Burwell introduced hip resurfacing into his practice in 2000 after visiting Mr McMinn in Birmingham and the following year gained further experience with a visit to Mr Ronan Tracey, also in Birmingham. These surgeons have achieved excellent survivorship of hip resurfacing in younger more physically active patients, who historically have required earlier revision surgery. Along with other specialist hip surgeons, in the UK and around the world, Mr Burwell has been very pleased with the outcome of hip resurfacing in his patients, many returning to unrestricted impact-type sporting activities.

The choice of hip resurfacing as a type of hip replacement, as reported in the National Joint Registry, peaked in the UK in 2006. As hip resurfacing is a ‘metal-on-metal’ implant it has unfortunately been tarnished by the poor results of metal-on-metal total hip replacements. In Mr Burwell’s own practice the results of hip resurfacing in both male and female patients has been excellent but, after a paper in the Lancet (2012) reporting the outcome of 32,000 hip resurfacings (NJR data) between 2003 and 2011, he changed his practice. In this British paper the best hip resurfacing outcomes were in 54mm or larger femoral heads and less good outcomes were found in patients with smaller femoral heads. These tended to be in women. It is for this reason that Mr Burwell no longer offers hip resurfacing to female patients. In this UK study only 23% of male patients undergoing hip resurfacing between 2003 and 2011 had a head size 54mm or above. Therefore, hip resurfacing may not be the best option in all male patients.

There are procedure-related risks with metal-on-metal hip resurfacing including femoral neck fracture, avascular necrosis (progressive loss of blood supply) of the remaining femoral head and metallosis (Adverse Reaction to Metal Debris ARMD) as seen in patients with metal-on-metal total hip replacements.

In 2017 Mr McMinn introduced a ceramic-on-polyethylene hip resurfacing implant, which will remove the risk of metallosis, but it will be some time before we know whether the results of this new implant will be similar or better to modern total hip replacements.

Mr Burwell assesses all patients on an individual basis and will discuss the risks versus benefits of all surgical procedures with the individual patient and, in particular, if hip resurfacing is an option. Modern digital imaging allows accurate measurement of the hip joint and is an important part of the overall assessment in patients considering hip resurfacing.

Total Hip Replacement

Primary Total Hip Replacement

Mr Burwell specialises solely in surgery to the hip and is recognised nationally as an expert in hip replacement surgery undertaking over 350 hip replacement operations each year. He offers the very last advanced techniques through Mako robotic-assisted surgery.

Modern hip replacement surgery was introduced by the English surgeon Sir John Charnley in the early 1960s. In the years since both operative techniques and engineering procedures have advanced so that patients can be reliably relived of hip pain and functional hip stiffness and look forward to returning to most recreational activities. In the majority of patients, the operation will last them for the rest of their life. Indeed, hip replacement has been termed ‘The Operation of the 20th Century’.

Over the first three decades of hip replacement developments concentrated on reliably fixing the hip implant to the bone and reducing postoperative infection.

There are two ways to fix the implants to the bone:

1. Cemented
2. Cementless / Uncemented.

Bone cement fixes implants immediately. Cementless implants are initially ‘mechanically fixed’ and over the first few weeks after surgery become ‘biologically fixed’. In other words, become solidly attached to the bone itself.

During the first three decades after the introduction of modern hip replacements, there was a reduction of post-operative infection to less than 1-2% achieved by improvements in theatre design and usage, antibiotics and skin preparation.

In the 1960s and 1970s, the bearing (i.e. the ‘ball and socket’) were made of metal and plastic respectively. The plastic wore resulting in loosening and failure of the implant. During the 1980s and 1990s, engineering and manufacturing improvements resulted in the development of better plastic, which wore much more slowly. The introduction of ceramic in the 1980s, much harder material than metal, was found to wear the plastic of the cup much more slowly. However, early ceramics were associated with a sudden fracture but modern ceramics (e.g. Biolox Delta) have a very low fracture rate.

Since 2000, with the widespread introduction of ‘crossed-linked polyethylene’ plastic, the wear rate has dropped significantly (with both metal and ceramic femoral heads) resulting in a reduced failure rate and improved long term survival of the hip replacement. This is despite hip replacements now being offered to younger and more active patients. Ceramic-on-ceramic bearings became popular allowing larger bearing diameters (associated with a reduction in dislocation) without an increase in wear. However, ceramic-on-ceramic bearings can ‘squeak’ and over the past couple of years their usage has reduced. Combining the benefits of ceramic (reduced wear) without the problems of ceramic (fracture) has allowed the introduction of ceramicised metal (Oxinium). The bearing combination of oxinium on crosslinked polyethylene (so-called ‘Verilast Technology for Hips’) has the potential to be a significant development as documented by the excellent outcome data on the Australia Joint Register (AJR, 2015).

Surgical techniques have also developed over time. Mr Burwell has personal experience of all three of the surgical approaches to the hip namely posterior, lateral (e.g. Hardinge) and anterior. Very few UK based surgeons have personal experience of all three approaches.

All surgical approaches have their benefits and risks. Over 70% of hip replacements in the UK (2017) are undertaken using the posterior approach. This is the approach favoured by Mr Burwell. Combining a modern (i.e. shorter and soft tissue sparing) posterior approach with sutures that do not require removal and wounds that are sealed with surgical glue allows hip incisions to heal quickly and with an excellent cosmetic appearance.

Minimal Invasive Surgical (MIS) techniques are increasingly popular around the world and are inevitably being marketed in the UK. However, there is very little evidence that so-called ‘MIS techniques’ reduce the length of hospital stays or improve the rate of rehabilitation compared to traditional surgical incisions. What the data do show is that complication rates are definitely increased with MIS hip replacement surgery. Mr Burwell is of the opinion that the length of the surgical incision should facilitate the operation being carried out to the best of his ability – optimising implant alignment and so reducing the risk of post-operative complications such as dislocation and leg length. It is the long term outcome that matters the most not the length of the scar! In reality, the length of the incision is appropriate to the individual patient.

Once the decision has been made to proceed with hip replacement surgery Mr Burwell will discuss with each patient the best option for them both with regard to implant fixation and bearing. The patient will then attend the Pre-Admission clinic to be assessed by the specialist nurses and anaesthetists. The patients are also invited to a Hip Class run by the physiotherapists and occupational therapists. There is a lot of education from the time of the decision to proceed with surgery and the date of admission.

Whilst for most patients a hip replacement is extremely successful in relieving pain and allowing a return to excellent function, as with all surgical procedures, there are both surgical and anaesthetic risks.

Surgical risks:

1. Infection
Despite all preventative measures being used it is impossible to eradicate the risk of infection. A recent meta-analysis (2014) from the United States confirmed a 2.5% rate of ‘surgical site infection’ and a 0.9% of ‘deep peri-prosthetic joint’ infection after primary hip replacement. Superficial infections may require a course of antibiotics. Deep infection usually requires a re-operation (revision) in one or two stages. Mr Burwell’s infection rate is less than 0.5%.

2. Thrombo-embolism
a. Symptomatic pulmonary emboli (0.15 – 0.4%)
b. Symptomatic deep vein thrombosis (0.3 – 0.6%)

All patients receive NICE recommended prophylaxis to reduce the risk of ‘blood clots’ after hip replacement surgery. These measures include mechanical devices (e.g. intermitted calf or foot compression during the operation and in the post-operative in-hospital stage). Some patients require injections. All patients require oral medication for 30-32 days post-surgery.

3. Dislocation
This is when the hip comes ‘out of joint’ and is most common within the first weeks after surgery. Figures vary with regard to the absolute risk. A study from Bristol (2008) reported that after first time primary hip replacement the risk of dislocation was 4.1% with the posterior approach. The risk of that hip dislocating again was 58%. In repeat revision hip replacement surgery the risk was greater at 8%. Mr Burwell’s personal dislocation rate for the posterior approach is less than 1%.

4. Leg length inequality
This is a very important issue for the patient. Mr Burwell pays particular attention to obtaining equal leg lengths at the time of surgery. To this end, Mr Burwell uses the combination of careful pre-operative planning (using accurate digital software on specially measured X-rays) and intra-operative techniques to achieve accurate restoration of the anatomy including leg length equality. However, all hip surgeons would accept that achieving absolute leg length equality is not possible for every patient. There are various reasons why patients may have differences in their leg lengths following surgery. These cannot always be overcome. Fortunately, whilst the published literature suggests that up to 5% of patients feel that their leg lengths are different 6 weeks after surgery this figure has reduced to 1% a year after surgery.

5. Neurovascular deficit
The femoral and sciatic (peroneal) nerves are at risk during hip replacement surgery. Sciatic nerve injuries, causing a ‘foot drop’, are more common than femoral nerve injuries. The risk depends on the complexity of the surgery. The reported risk is between 0.17% (Morrey, 2005) and 0.32% (Parvizi, 2013). Partial peroneal nerve palsies take 12 months to recover and full peroneal nerve palsies take 18 months to recover. However, not all nerve palsies recover.

Anaesthetic risks:

Previously hip replacement was usually undertaken using a general anaesthetic. Nowadays regional anaesthetic techniques, such as a spinal anaesthetic (similar to when mothers are in labour), and local anaesthetic infiltration of the surgical incision are more common. This has resulted in a reduction of blood loss and post-operative nausea and sickness, better post-operative pain control allowing earlier mobilisation and reduced medical risks such as:

1. Cardiac – heart attack, heart failure
2. Stroke
3. Kidney impairment

In addition, there are other factors that can have an effect on post-operative rehabilitation. These include medical co-morbidities (e.g. Parkinson’s Disease), prolonged pre-admission immobility and social factors.

Revision Hip Replacement (under treatments)

Whilst the majority of patients who undergo hip replacement never require a further operation (revision) some do. Those patients who are younger and heavier at the time of their primary hip replacement surgery are at increased risk of requiring revision surgery.

Causes for revision can be divided in to early (most common within the first year) and late (occurring after this time, maximal at 5 years post-surgery).

The UK National Joint Registry reports the following risks:

Early:

1. Dislocation
The reported risk is around 2-4%

2. Infection
The reported risk is around 1-2%

3. Peri-Prosthetic Fracture (fracture of the pelvic to thigh bone usually after a fall)
The reported risk is 0.9%

Late:

1. Aseptic loosening (wear of the bearing)

2. Pain

3. Adverse soft tissue reaction to particulate debris (most commonly these days following metal-on-metal hip replacements)

Revision surgery is usually more complex than primary surgery and the risks higher. This is because the bone of both the pelvis and femur is often weakened by the wear process. There is a risk of fracture to both the pelvis and femur during implant removal or whilst inserting the new hip implant.

More recently, often the stem (that part of the hip replacement that is inserted into the thigh bone) can be left and the socket/cup in the pelvis revised along with a new bearing. In such cases, the recovery rate can be similar to that after a primary hip replacement.

In more complex surgery, often when bone grafting is required, protected weight bearing with crutches may be necessary for up to 3 months post-surgery.

Mr Burwell will discuss individual risks with each patient as these often vary and are patient-specific.

Meet the team

Matthew Burwell is one of only a few orthopaedic surgeons in the UK specialising exclusively in treating hip conditions. Hip replacements are a large part of his practice. Many patients are referred to him from other orthopaedic specialists.

Matthew Burwell
Consultant Orthopaedic Surgeon

Dave Hepburn
Specialist Senior Physiotherapist

Dr Graham Robinson
Consultant Radiologist

Hannah Nestor
Specialist Theatre Nurse

Laura Davies
Medical Secretary