Cartilage-Surgery

Great Results for Joint Pain and Injury

Knee Joint Replacement

Knee joint replacement resurfaces the worn surfaces of an arthritic knee with metal and plastic components. It is one of the most reliable operations in orthopaedic surgery for pain that no longer responds to injections, physiotherapy or keyhole surgery — but the right operation matters as much as the operation itself.

Mr Chatenya Chauhan completed fellowship training in joint replacement at the Royal Orthopaedic Hospital in Birmingham and offers three approaches to the arthritic knee: partial replacement using the Oxford medial unicompartmental knee, total replacement using the ATTUNE knee system, and robotic-assisted replacement using the VELYS system. Which one suits you depends on how much of the joint is worn, the state of your ligaments and what you need the knee to do.

Not every arthritic knee needs replacing. Where the wear is mild or moderate, injection therapy, arthroscopy and cartilage-preserving surgery are discussed first. A replacement is offered when the joint surface is genuinely worn out and pain is limiting your daily life and sleep.

Knee replacement options

Partial — Oxford medial

Resurfaces the inner compartment only, keeping your own cruciate ligaments and the rest of the joint. Smaller operation, quicker recovery and a more natural feeling knee. In clinical use since 1976.

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Total — ATTUNE

Replaces the whole joint surface when wear affects more than one compartment. A modern implant design intended to give stable, predictable motion. In use worldwide since 2011.

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Robotic — VELYS

Robotic assistance used alongside the ATTUNE implant to fine-tune alignment, bone cuts and soft-tissue balance during the operation. Introduced in 2020.

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Partial knee replacement — the Oxford medial unicompartmental knee

In many people arthritis wears out only the medial (inner) compartment of the knee, while the outer compartment and the kneecap remain healthy. A partial, or unicompartmental, replacement resurfaces just that worn compartment and leaves everything else — including both cruciate ligaments — untouched. The Oxford knee is a mobile-bearing medial partial replacement first implanted in 1976 and now in its third design generation, introduced in 1998. It is the most widely used and most extensively studied partial knee replacement in the world.

The good points

  • It keeps your own knee. Both cruciate ligaments are retained, so the knee moves more normally and a high proportion of patients describe it as feeling like a natural joint rather than an artificial one.
  • Smaller operation. Less bone is removed, blood loss is lower and the incision is shorter than for a total knee replacement.
  • Faster recovery. Most patients are walking on the day of surgery and back to normal daily activity considerably sooner than after a total replacement.
  • Better bend. Range of movement is typically greater than after a total knee replacement, which matters for kneeling, stairs and getting in and out of a car.
  • Lower medical risk. Published registry and comparative data show lower rates of serious complications such as infection, thromboembolism and death in the early period after surgery compared with total knee replacement.
  • It does not burn bridges. If arthritis later develops elsewhere in the knee, the partial can usually be converted to a total knee replacement.

How long does it last?

  • Long-term series of the Oxford medial partial knee report survivorship of roughly 94–95% at 10 years and around 91% at 15 years in experienced hands.
  • National Joint Registry data for partial knee replacement as a group show higher revision rates than total knee replacement — in the order of 12–13% revised by 10 years — partly because a partial knee is technically easier to revise, so surgeons revise it sooner.
  • A large 2019 Lancet meta-analysis of registry and case-series data estimated that around 70% of unicompartmental knee replacements are still in place at 25 years.
  • Outcomes are strongly linked to case selection and to surgeon volume: results are best where the implant is used regularly and in properly selected knees.

Who it suits

  • Arthritis confined to the medial compartment, confirmed on X-ray and examination.
  • An intact and functioning anterior cruciate ligament.
  • A deformity that is correctable, with good movement and a knee that is not stiff.
  • Pain that is felt mainly on the inner side of the knee.

Total knee replacement — the ATTUNE knee system

Where wear involves more than one compartment, or where the ligaments or alignment will not support a partial, the whole joint surface is replaced. The worn ends of the femur and tibia are resurfaced with metal components separated by a polyethylene bearing, and the kneecap is resurfaced where appropriate. The ATTUNE knee system was introduced in 2011 and has since become one of the most widely implanted total knee designs worldwide. It was developed to improve stability and smoothness of motion through the mid-flexion range — the part of the arc used when rising from a chair or going down stairs.

The good points

  • Reliable pain relief. Total knee replacement remains one of the most consistently successful operations in medicine for advanced arthritis, with the great majority of patients reporting substantial and lasting improvement in pain.
  • It treats the whole joint. Arthritis in every compartment is dealt with in one operation, so there is nothing left to wear out and cause pain later.
  • Designed for smoother motion. The gradually changing femoral shape and matched bearing surface are intended to reduce the sensation of instability some patients describe in mid-flexion.
  • A full range of sizes and options. Cemented and cementless fixation, rotating-platform and fixed bearings and a range of component sizes allow the implant to be matched to your anatomy.
  • Predictable, well-documented recovery. Rehabilitation protocols are well established, and the operation is suitable for a wide range of ages and deformities.
  • It works with robotic assistance. The same implant can be inserted with the VELYS system if robotic assistance is appropriate for you.

How long does it last?

  • National Joint Registry figures for cemented total knee replacement as a whole show roughly 3–4% revised by 10 years, so about 96–97% are still in place at ten years.
  • The 2019 Lancet meta-analysis estimated that approximately 82% of total knee replacements last 25 years.
  • The ATTUNE system has been in clinical use since 2011, so registry follow-up now extends beyond ten years; its published revision rates are broadly in line with, or slightly better than, the average for cemented total knees in the National Joint Registry.
  • Implants tend to last longer in older, less heavily loaded patients; younger and more active patients should expect a higher lifetime chance of needing revision surgery.

What the operation involves

  • Usually a spinal anaesthetic with sedation, or a general anaesthetic, discussed with the anaesthetist beforehand.
  • Around one to two hours in theatre, with implant position and soft-tissue balance checked throughout.
  • Standing and walking with the physiotherapist on the day of surgery or the following day.
  • Most patients go home within one to three days, with a rehabilitation plan and follow-up with Mr Chauhan.

Risks to be aware of

  • Infection, blood clots in the leg or lung, bleeding, stiffness and persistent pain or swelling.
  • Injury to nerves or blood vessels, fracture around the implant, and numbness around the scar.
  • Loosening or wear of the implant over time, which may eventually require revision surgery.

Robotic knee replacement — the VELYS robotic-assisted solution

Robotic assistance does not replace the surgeon; it gives the surgeon live measurements during the operation. The VELYS robotic-assisted solution was introduced in 2020 and is used together with the ATTUNE implant. It works without a pre-operative CT scan: the anatomy of your knee is mapped in theatre, and the system reports alignment, gap balance and joint movement as the knee is taken through its range, so the bone cuts and soft-tissue releases can be planned and verified before anything is fixed in place.

The good points

  • Objective data, not just judgement. Alignment and ligament balance are measured in real time through the full range of movement rather than estimated.
  • Accurate, reproducible bone preparation. Published series show implant positioning closer to the pre-operative plan and fewer outliers than with conventional instruments.
  • No extra scan and no extra radiation. Unlike CT-based robotic systems, VELYS is image-free, so there is no additional pre-operative imaging appointment.
  • Personalised balancing. Soft-tissue releases can be minimised and the implant position adjusted to your own anatomy and ligament tension.
  • Encouraging early results. Early comparative studies report less early post-operative pain, reduced analgesia use and faster achievement of rehabilitation milestones in some patients.
  • Familiar implant. The bearing surfaces are the ATTUNE components described above, which already have a substantial registry record.

How long does it last?

  • The implant used is the ATTUNE knee, so the long-term survivorship figures above apply: about 96–97% still in place at 10 years for cemented total knees, and roughly 82% at 25 years across total knee replacement as a whole.
  • VELYS itself has only been available since 2020, so there is no long-term survivorship data specific to robotic assistance. Published evidence at present covers accuracy of implant positioning and early recovery, typically at one to two years.
  • Whether more accurate positioning translates into implants lasting longer is a reasonable expectation but is not yet proven, and will take another decade of registry follow-up to answer.

What it does not change

  • The implant, the anaesthetic and the rehabilitation are the same as for a standard total knee replacement.
  • The risks of joint replacement listed above still apply.
  • Robotic assistance does not make an unsuitable knee suitable; case selection still comes first.

Survivorship figures quoted on this page are drawn from the National Joint Registry for England, Wales, Northern Ireland, the Isle of Man and Guernsey, from published long-term implant series and from a 2019 meta-analysis in The Lancet. They describe groups of patients, not individuals: your own result depends on your age, weight, activity, bone quality and the reason for surgery. Mr Chauhan will discuss the figures that apply to your knee at your consultation.

Discuss your knee with Mr Chauhan

Joint replacement is one part of a wider knee surgery practice that also covers ligament reconstruction, arthroscopy, cartilage preservation and injection therapy. Book a consultation at the Southend-on-Sea, Leigh-on-Sea, Chelmsford or London clinics, or read the consultation and treatment fees first.