Total Hip Replacement

What is Total Hip Replacement?

Total hip replacement (THR) — also known as total hip arthroplasty — is a surgical procedure in which the damaged surfaces of the hip joint are removed and replaced with precisely engineered artificial components, creating a new, smooth, pain-free bearing surface. It is among the most commonly performed and most successful elective surgical procedures worldwide.

Approximately 90,000 total hip replacements are performed in the UK each year. The National Joint Registry (NJR), active since 2003, now holds data on over 1.2 million hip replacements performed in the UK — making it one of the most comprehensively monitored surgical procedures anywhere in the world. Mr. Lodge performs total hip replacement at York Teaching Hospital (NHS) and at Nuffield Health York Hospital and Ramsay Clifton Park Hospital (private), serving patients from across North Yorkshire, West Yorkshire and East Yorkshire. He is a registered NJR surgeon, and data on outcomes from his patients is routinely submitted and monitored to ensure the highest standards are maintained.

The average age of patients undergoing hip replacement in the UK is around 68, though this should not imply that younger patients are not appropriate candidates. Age alone is not a significant limitation to surgery — the decision is based on the severity of symptoms, functional limitation and overall health. Younger patients often benefit enormously from hip replacement and, with modern implants and bearing surfaces, can expect excellent longevity from their reconstruction.

How the Operation Works

Total hip replacement involves the surgical removal of the damaged arthritic surfaces of the hip joint and their replacement with carefully selected implant components. The result is a new, artificial ball-and-socket joint — made from combinations of metal, ceramic and plastic — that recreates smooth, pain-free movement.

The operation begins with the surgeon dividing the neck of the femur (thigh bone) to remove the worn femoral head — the ball of the natural hip joint. This allows access to both the socket (the acetabulum, in the pelvis) and the femoral canal (the hollow centre of the thigh bone). The damaged articular cartilage lining the socket is then removed, and a new metal acetabular cup is implanted into the pelvis. A liner — made of ceramic or highly cross-linked polyethylene — is locked or cemented into this cup.

A metal stem is then carefully sized and introduced into the femoral canal and secured in position, either with bone cement or by relying on the bone growing directly onto the implant surface (uncemented fixation). A ceramic or metal femoral head is then attached to the top of the stem. When the hip is reduced — the ball placed back into the socket — the new artificial bearing is created.

All options — from fixation method to bearing surface to head size — are tailored specifically to each patient's anatomy, age, bone quality, activity level and clinical circumstances. These decisions are discussed with you in advance of surgery so that you fully understand the plan for your individual reconstruction.

How Are Implants Fixed to Bone?

There are two fundamental principles by which hip implants are secured to bone: cemented fixation and uncemented fixation. Both are well-established techniques with excellent long-term results, and the choice between them depends on a number of patient-specific factors.

In some patients, a hybrid fixation is used — where one component is cemented and the other is uncemented. For example, a cemented femoral stem combined with an uncemented acetabular cup is a commonly used and well-evidenced combination. The right approach for each patient is selected on an individual basis and discussed fully before surgery.

Bearing Surface Options

The bearing surface is the articulating interface between the femoral head and the acetabular liner — in effect, the moving part of the hip replacement. The choice of bearing surface is one of the most important decisions in hip replacement surgery, as it directly influences wear, longevity and the risk of complications over time.

The ideal bearing surface produces minimal wear debris, is biocompatible with the surrounding tissues, allows a large head size to be used, and performs reliably for many decades. The options available today represent significant advances over those used in earlier generations of hip replacement.

Dual Mobility — A Specialist Option for High-Risk Patients

For the majority of patients, ceramic-on-highly cross-linked polyethylene provides an excellent and reliable bearing choice. However, in a specific group of patients where the risk of dislocation is significantly elevated, Mr. Lodge may recommend a dual mobility (DM) construct in place of a conventional bearing.

A dual mobility cup works on the principle of two independent articulations: a small ceramic or metal femoral head moves within a large polyethylene mobile liner, which itself moves within the outer metal acetabular shell. This "ball within a ball" design effectively creates a much larger functional femoral head diameter than would otherwise be possible — dramatically increasing the arc of movement required before the head can lever out of the socket and dislocate. Reported dislocation rates with dual mobility articulations in appropriately selected patients range from 0% to 1.1%, even in those at high risk.

A 2022 study published in The Bone & Joint Journal (Yates et al.) evaluated modular dual mobility articulations specifically in patients with adverse spinopelvic mobility undergoing primary total hip arthroplasty. In a cohort where one or more factors associated with adverse spinopelvic mobility were present, the dual mobility bearing conferred excellent stability — with no revisions for dislocation reported at two-year follow-up, and a Kaplan-Meier survival rate of 99.1%. The authors concluded that dual mobility bearings confer stability in this high-risk group and represent a reliable solution for patients in whom conventional bearing surfaces carry an unacceptably elevated dislocation risk.

Beyond spinopelvic stiffness, dual mobility constructs are also considered in other patient groups where dislocation risk is elevated for different reasons. These include patients with neurological disorders — such as Parkinson's disease or a history of stroke — where altered muscle tone, coordination and proprioception impair the body's ability to protect the hip joint during movement. In these groups, the inherent mechanical stability provided by the dual mobility design compensates for the reduced muscular and neuromuscular protection that would otherwise guard against dislocation.

The Importance of Head Size — Optimising Stability Without Compromising Wear

The diameter of the femoral head component has a direct and well-evidenced influence on the stability of a hip replacement. A larger head increases what is known as the "jump distance" — the distance the femoral head must travel before it can lever out of the socket — and provides a wider impingement-free range of movement. Both of these effects translate into a meaningfully lower risk of dislocation.

Where anatomy and implant sizing permit, Mr. Lodge's approach is to use as large a femoral head as possible. In practice, this most commonly means a 36 mm ceramic head — the size at which the evidence most clearly demonstrates a benefit in terms of dislocation risk reduction, and for which the wear data with modern highly cross-linked polyethylene is particularly reassuring.

It is important to note that there are practical limits to head size — dictated by the diameter of the acetabular component that can be implanted given each patient's individual anatomy. Not every patient can accommodate a 36 mm head, and in smaller acetabular components a 32 mm head may be required. Where this is the case, wear performance with modern polyethylene remains excellent regardless. The goal is always to use the largest head that can be safely implanted within a correctly sized and positioned socket — maximising stability without compromising fixation or liner integrity.

Heads larger than 36 mm (≥40 mm) are not routinely used in Mr. Lodge's standard primary hip replacement practice. Registry data have shown that very large heads do not confer additional dislocation benefit over 36 mm, and may carry a modestly increased risk of infection and all-cause revision — likely related to the larger surgical exposure required and taper mechanics. Beyond 36 mm, bigger is not consistently better.

The Surgical Approach

The "surgical approach" refers to the route taken to access the hip joint during the operation — that is, which muscles and soft tissues are divided or moved aside to allow the surgeon to see and work on the joint. The choice of approach influences the recovery experience, dislocation risk and the scope of surgery that can be safely performed.

Over the years, several different approaches have been developed and refined, each with their own advantages and proponents. The fundamental requirement of any approach is to provide adequate visualisation of both the acetabulum and the femur, whilst minimising damage to the surrounding muscles, nerves and blood vessels.

The Posterior Approach

Mr. Lodge's practice is based on the posterior approach to the hip — an approach he has used extensively throughout his surgical career and which he considers to be the safest, most reliable and most versatile technique available.

In the posterior approach, the hip is accessed from the back of the buttock. The skin and overlying fascia are divided, and the muscles are carefully split — rather than cut through — to gain access to the posterior hip capsule. The short external rotator muscles are released along with the posterior capsule to expose the hip joint, creating a protective flap that also shields the sciatic nerve during the procedure. This provides excellent circumferential visualisation of the acetabulum and safe access to the femur.

One of the key advantages of the posterior approach is that the hip abductor muscles — the muscles responsible for stabilising the pelvis during walking — are not significantly involved in the exposure. The nerve supply to these muscles is preserved, which means that a limp following this approach is uncommon. The posterior capsule and short external rotators are carefully repaired and reattached at the end of surgery, restoring the soft tissue envelope and reducing the risk of dislocation.

What About Other Approaches?

The direct anterior approach (DAA) has gained increasing popularity in some centres, particularly in continental Europe and North America, where proponents argue it is a more "muscle-sparing" technique.

The clinical evidence to date has not demonstrated a clear or consistent advantage of the anterior approach over a well-performed posterior approach in terms of functional outcomes, dislocation rates or long-term results. Equally, the anterior approach does have its own learning curve and specific complications. Given Mr Lodge’s experience and outcome results using the posterior approach — across primary and revision cases — he continues to base his practice on the approach he knows best and has demonstrated the most reliable results with.

Mr. Lodge is always happy to discuss surgical approach in detail at consultation, including what to expect from the recovery and what the scar will look like.

What Are the Risks?

Total hip replacement is one of the most reliably successful procedures in modern surgery. The vast majority of patients experience excellent outcomes with no significant complications. That said, as with any major operation, it is important that you understand the risks involved before giving your consent to proceed.

The potential complications listed below are uncommon, but they are significant enough to warrant careful discussion. All of these will be covered in detail at your pre-operative consent appointment, and you are encouraged to raise any specific concerns at that stage.

What Results Can You Expect?

The results of total hip replacement are extremely reliable. The procedure has one of the highest patient satisfaction rates of any elective surgical procedure, with the overwhelming majority of patients experiencing dramatic improvements in pain, function and quality of life.

Following total hip replacement, patients typically experience a significant and often rapid reduction in pain — frequently within days of surgery. Over the weeks and months that follow, as healing progresses and the surrounding muscles recover, function continues to improve. Most patients are walking freely, with good range of movement and without significant pain, within six to twelve weeks of their operation.

Modern implants, particularly those using ceramic bearing surfaces, are expected to last well beyond twenty years in the majority of patients. Younger, more active patients may eventually require a revision procedure during their lifetime, but with careful implant selection and technique — particularly with regard to bone preservation — revision surgery can usually be performed with a primary-type implant when the time comes.