A dual mobility hip replacement uses two bearing surfaces instead of one: a small femoral head locked inside a larger polyethylene head, which in turn glides within the cup. The result is a hip that is far harder to dislocate. Mr Shakir Hussain uses the Smith and Nephew OR3O Dual Mobility System for selected primary and revision hip replacements at the Royal Orthopaedic Hospital, Priory Hospital Edgbaston, and Harborne Hospital in Birmingham.
What Is a Dual Mobility Hip Replacement?
A dual mobility hip replacement is a total hip replacement built around two articulations rather than one. A small femoral head snap-fits inside a large polyethylene head, and that larger head moves freely against a polished liner fixed inside the acetabular shell. The large outer head behaves like a much bigger ball, which makes the joint substantially more stable.
From the outside in, an OR3O dual mobility hip has four layers.
- The acetabular shell. A titanium shell fixed into the prepared socket in the pelvis, either press-fitted or cemented depending on the case.
- The polished liner. In the OR3O system this is made of OXINIUM DH, a diffusion-hardened ceramicised metal. It locks into the shell and provides the smooth surface the mobile head glides against.
- The mobile polyethylene head. A large head made of highly cross-linked polyethylene (XLPE). It is not fixed; it rotates freely within the liner.
- The small femoral head. An OXINIUM head that locks inside the polyethylene head and sits on the femoral stem, exactly as in a conventional hip replacement.
The stem in the thigh bone and the fixation choices are the same as in any total hip replacement. The general anatomy of a hip implant, including stems, fixation, and bearing materials, is covered in the companion guide to hip replacement implants.
How Does Dual Mobility Reduce the Risk of Dislocation?
Dislocation happens when the femoral head levers out of the cup. The larger the head, the further it must travel before it can escape, a distance surgeons call the jump distance. A dual mobility bearing gives the hip the jump distance of a very large head without the wear problems that solid large heads caused in older designs.
Dislocation after a first-time hip replacement affects roughly 1 to 3 percent of patients in registry data, and instability remains one of the most common reasons a hip replacement needs early revision. Comparative studies consistently show lower dislocation rates with dual mobility bearings, both in primary surgery for higher-risk patients and in revision surgery for instability.
Implant choice is only one part of stability. Mr Hussain uses a tissue-sparing posterolateral approach with a careful soft tissue repair, which itself keeps dislocation rates low. A dual mobility bearing is added on top of that technique for patients whose risk remains elevated.
What Is the Smith and Nephew OR3O Dual Mobility System?
OR3O is Smith and Nephew's dual mobility hip system, launched in 2019 for use in both primary and revision hip replacement. It was the first dual mobility system to use an OXINIUM DH liner in place of the cobalt chrome liner found in traditional dual mobility designs.
That change matters. In a conventional dual mobility construct, the polyethylene head moves against a cobalt chrome surface, and cobalt chrome can release metal ions through wear and corrosion. Replacing it with OXINIUM DH removes most of that concern while keeping the stability advantage of the dual mobility design.
What makes OR3O different: traditional dual mobility designs pair a polyethylene head with a cobalt chrome liner. The OR3O system replaces that cobalt chrome with OXINIUM DH, a diffusion-hardened ceramicised metal that showed reduced wear and lower metal ion release in laboratory testing.
Dual Mobility in Practice: Two Patient Examples
The x-rays below show the OR3O system used for two of Mr Hussain's patients, both treated at the Royal Orthopaedic Hospital, and both with a risk of dislocation well above average. The first had severe hip arthritis alongside spinal problems and limited mobility; the second, muscle weakness after previous spinal surgery.
An elderly patient with severe arthritis of the right hip, alongside spinal problems and limited mobility. Both factors significantly raise the risk of dislocation with a standard hip replacement.
The same hip after total hip replacement using the OR3O dual mobility system, with the cup secured by screws. The large mobile bearing protects a hip that cannot rely on normal spinal movement and muscle control.
Pre-operative templating for a patient with muscle weakness following previous spinal tumour surgery. Every dual mobility hip is planned digitally, so implant size and position are decided before the operation begins.
The completed OR3O dual mobility hip replacement, matching the digital plan. The extra stability of the dual mobility bearing compensates for reduced muscle control around the hip.
What Is OXINIUM and Why Does It Matter?
OXINIUM is oxidised zirconium: a metal alloy whose surface is transformed into a ceramic during manufacturing. It combines the smooth, hard-wearing surface of a ceramic with the toughness of a metal, so it resists both wear and fracture. Smith and Nephew has used OXINIUM femoral heads in hip replacement, and OXINIUM components in knee replacement, for over two decades.
The liner in the OR3O system uses OXINIUM DH, where DH stands for diffusion hardened. The hardened zone extends deeper below the surface than in standard OXINIUM, which is what allows it to serve as the gliding surface of a dual mobility construct.
OXINIUM also contains very little nickel, the metal most often implicated in metal sensitivity. For patients with a documented metal allergy, an OR3O construct is often a reassuring option; this is covered further in the FAQs below.
Who Benefits Most from a Dual Mobility Hip Replacement?
Dual mobility is chosen for patients whose risk of dislocation is higher than average. For most first-time hip replacements a standard bearing remains an excellent choice, so Mr Hussain uses dual mobility selectively rather than routinely.
Situations where he may recommend it include:
- A previous dislocation, or revision surgery being performed because a hip replacement keeps dislocating.
- A fused or very stiff spine. When the spine cannot flex, the hip is forced through a larger arc of movement, which raises dislocation risk. The same issue is explained in the article on hip surgery after spinal fusion.
- Neurological conditions such as Parkinson's disease or a previous stroke, where muscle control around the hip is reduced.
- Weak abductor muscles, whether from previous surgery, chronic hip disease, or general frailty.
- Hip replacement after a hip fracture, where dislocation rates are known to be higher than in planned surgery for arthritis.
- Cognitive impairment, where following post-operative movement advice reliably may be difficult.
Whether any of these apply to you is assessed at consultation, as part of the wider implant discussion around hip replacement surgery in Birmingham.
Dual Mobility in Revision Hip Surgery
Recurrent dislocation is one of the leading reasons a hip replacement needs revising. Exchanging the bearing for a dual mobility construct is now a standard part of revision surgery for instability, and roughly a quarter of hip revisions recorded in the American Joint Replacement Registry use a dual mobility implant.
The OR3O system was designed for revision as well as primary use, and it is one of the tools Mr Hussain draws on in his hip revision replacement practice. Before choosing it, he establishes why the hip is unstable. If the cup or stem is malpositioned, a bearing exchange alone will not solve the problem, so the assessment covers component position, soft tissue quality, and spinal stiffness.
If your hip replacement has dislocated, the dedicated page on hip replacement instability explains the causes and the full range of treatment options.
What Are the Drawbacks of Dual Mobility?
No implant choice is free of trade-offs, and a balanced decision needs the other side of the ledger.
- Intraprosthetic dislocation. A rare failure unique to dual mobility, where the small head separates from the polyethylene head. It was mainly seen in older designs and after forceful manipulation of a dislocated hip; modern locking geometry has made it uncommon.
- Two wearing surfaces. The bearing moves at two interfaces rather than one, which in theory produces more polyethylene wear. Modern highly cross-linked polyethylene has substantially reduced this concern.
- A shorter track record for OR3O specifically. Dual mobility as a concept dates from the 1970s, but the OR3O system has only been implanted since 2019, so its long-term registry data is still accumulating.
- Unnecessary for most standard hips. A patient without dislocation risk factors gains little from the extra complexity, which is why Mr Hussain does not use dual mobility routinely.
What Is Recovery Like After a Dual Mobility Hip Replacement?
Recovery follows the same enhanced recovery pathway as any modern total hip replacement: walking on the day of surgery, home within one or two nights for most patients, and a return to most activities over six to twelve weeks.
One practical difference is that the extra stability often allows movement precautions to be relaxed earlier, which many patients find liberating in the first weeks. Your individual advice will depend on your operation and your risk factors.
The practical detail of the whole journey is covered in the guides to preparing for hip replacement surgery and what happens during hip replacement surgery.
Frequently Asked Questions
Is the implant called OR3O or OR30?
The correct name is OR3O, ending in the letter O rather than the number zero. It is frequently written as OR30 online. Both spellings refer to the same Smith and Nephew dual mobility hip system.
Will I still need hip precautions after a dual mobility hip replacement?
Usually fewer. The design is much more stable than a standard bearing, and many surgeons relax the traditional movement restrictions. Mr Hussain will give you individual guidance based on your operation and your risk factors.
How long does a dual mobility hip replacement last?
Dual mobility implants have been used in Europe since the 1970s, and modern versions show survival comparable to conventional hip replacements at 10 years. The OR3O system was launched in 2019, so its own registry record is still building, but its materials are designed to reduce the wear seen in earlier designs.
Does the OR3O implant suit patients with metal allergy?
It is often a good option. OXINIUM contains very little nickel, the metal most commonly linked to sensitivity, and the OXINIUM DH liner removes the cobalt chrome surface used in traditional dual mobility designs. Tell Mr Hussain about any metal allergy at your consultation.
Can dual mobility fix a hip replacement that keeps dislocating?
Often, yes. Exchanging the bearing for a dual mobility construct is one of the main surgical treatments for recurrent dislocation. Mr Hussain assesses the cause of the instability first, since component malposition or muscle weakness may also need correcting.
Is a dual mobility hip replacement suitable for younger patients?
Selectively. Younger, active patients place more cycles on the bearing, and long-term wear data for dual mobility in this group is still accumulating. Mr Hussain typically reserves dual mobility for patients with specific dislocation risk factors rather than using it routinely in the young.
Mr Shakir Hussain
Consultant Hip and Knee Surgeon at the Royal Orthopaedic Hospital Birmingham. Specialist in hip resurfacing, hip replacement, robotic knee replacement, and complex revision surgery.