A comprehensive patient guide — from types of procedure and surgical approaches through to implant selection, complications, and recovery.
Medical Disclaimer: The information on this page is for general guidance only and does not constitute medical advice. Always discuss your individual circumstances with a qualified orthopaedic surgeon or GP.
Knee replacement (total knee arthroplasty, or TKA) resurfaces a knee joint damaged by arthritis or injury with metal and plastic components. It is one of the most successful operations in medicine, with the vast majority of patients achieving significant, lasting pain relief and restored function. Roughly 110,000 knee replacements are performed each year in the UK.
Knee replacement is typically considered when:
The most common type. The entire joint surface — both the femur (thigh bone) and tibia (shin bone) ends — is resurfaced with metal components, with a plastic spacer between them. The back of the kneecap may also be resurfaced.
Only the damaged compartment of the knee is replaced, leaving healthy bone and tissue intact. Recovery tends to be faster, the knee often feels more natural, but not all patients are suitable candidates — it works best when arthritis is confined to one compartment.
Only the kneecap joint surface is replaced. Suitable only for isolated kneecap arthritis in carefully selected patients.
Increasingly available at specialist centres, robotic assistance helps surgeons achieve more precise implant positioning in real time. Evidence suggests improved short-term outcomes; long-term comparative data continues to develop.
The surgical approach determines how the surgeon opens the knee joint to access the joint surfaces. The choice affects soft-tissue trauma, early recovery, and quadriceps function.
The most widely used approach in knee replacement. The incision extends into the quadriceps tendon just medial to (inside of) the kneecap, which is then reflected (turned aside) to fully expose the joint. This provides maximum joint exposure and is highly reliable for complex cases and revision surgery. The trade-off is a more significant disruption to the quadriceps mechanism, which can prolong the time it takes to regain a straight-leg raise and full quadriceps strength in early recovery.
The incision curves below the vastus medialis muscle (the inner-lower quadriceps) without cutting into the quadriceps tendon. The kneecap is lifted rather than turned. This preserves the quadriceps mechanism entirely, typically resulting in less post-operative pain, earlier straight-leg raises, and quicker return to confident walking. It is technically more demanding and is not always feasible in patients with very muscular or stiff knees.
A compromise between the medial parapatellar and subvastus approaches. The incision splits through the belly of the vastus medialis muscle — without cutting the tendon — providing better exposure than the subvastus while causing less disruption than the full parapatellar technique. Often used when the subvastus approach is too restrictive but full tendon cutting is considered unnecessary.
As with hip replacement, no single knee approach is universally superior. The best approach for you depends on your anatomy, the complexity of the case, and your surgeon's training and preference. Surgeons typically achieve the best results with the approach they use most frequently.
Knee implant choices are tailored to your age, bone density, weight, and activity demands. The same principles of fixation and bearing surface apply as in hip replacement, with some knee-specific considerations.
The implant components are bonded to the bone surfaces using polymethyl methacrylate (PMMA) bone cement. Provides immediate stability and has the most extensive long-term evidence base of any fixation method. The current gold standard for the vast majority of knee replacement patients.
The implant surface is porous or coated to encourage bone to grow into it over 4–6 weeks. Increasingly used for younger patients where very long-term fixation is the priority. Requires excellent bone quality and strict weight-bearing protocols in the early post-operative period while osseointegration occurs.
Typically involves a cemented tibial component (where fixation quality is most critical) combined with a cementless femoral component. Allows surgeons to optimise fixation where the bone quality and geometry best suit each method.
A highly polished cobalt-chromium femoral component articulates against a highly cross-linked polyethylene (XLPE) tibial insert. Modern XLPE is significantly more wear-resistant than older polyethylene, with an outstanding long-term track record. This is the dominant bearing combination in knee replacement worldwide.
A zirconium alloy femoral component with an oxidised ceramic surface layer, articulating against polyethylene. Combines the strength of metal with the low wear of ceramic. Generates significantly less wear debris than standard cobalt-chrome, which may benefit younger patients concerned about long-term particle-related bone loss.
The polyethylene spacer is designed to rotate slightly within the tibial tray, distributing wear more evenly and potentially improving conformity of movement. Some designs aim to improve knee kinematics and feel more natural during activities. Evidence on long-term superiority over fixed-bearing designs is mixed; the choice often depends on surgeon preference and patient-specific anatomy.
Knee replacement is a safe and routinely successful procedure, but all surgery carries risk. Understanding each complication — alongside the protocols used to prevent it — empowers you to participate actively in your own safety.
Deep infection of a knee replacement is serious and may require further surgery, including temporary removal of the implant (two-stage revision). Prevention strategies: laminar-flow operating theatres, pre-operative chlorhexidine skin washes, mandatory intravenous antibiotics before incision, and antibiotic-loaded cement in selected high-risk cases.
A significant risk with any lower-limb surgery. The knee's proximity to major veins makes DVT prevention especially important. Standard protocols: sequential compression devices (pneumatic leg sleeves) intraoperatively, early mobilisation from Day 0 or 1, graduated compression stockings, and anticoagulant medication (aspirin, rivaroxaban, or enoxaparin) for 2–6 weeks post-operatively.
A small percentage of knee replacement patients develop significant post-operative stiffness where scar tissue limits range of motion. Early, consistent physiotherapy is the most effective prevention. Patients who do not achieve at least 90 degrees of flexion by 6–8 weeks may require a manipulation under anaesthetic (MUA) — a brief procedure to break down restricting scar tissue.
Registry data shows approximately 90% of knee replacements function well at 15 years and 80% at 20 years. Loosening can occur over time as microscopic wear debris accumulates and causes bone loss around the implant. Staying at a healthy weight and avoiding high-impact activities significantly extends implant lifespan. When loosening occurs, revision surgery is generally effective.
The majority of patients experience substantial pain relief after knee replacement. However, a small percentage (estimated 10–20%) report ongoing pain that does not fully resolve. This is more common when pre-operative expectations are not aligned with realistic outcomes, or when the source of pain is complex. Thorough pre-operative assessment helps identify patients at higher risk of persistent pain.
Contact your surgical team or go to A&E immediately if you experience any of the following after your knee replacement:
Knee replacement recovery requires active participation — physiotherapy is not optional, it is central to a good outcome.
For a detailed physiotherapy programme, recovery phase guidance, and home safety checklist, visit our dedicated Rehabilitation Guide.
Modern knee replacements are highly durable. Registry data shows around 90% are still functioning well at 15 years, and 80% at 20 years. Factors affecting longevity include age, weight, activity level, and implant design. Staying at a healthy weight and avoiding high-impact activities helps prolong the life of the implant.
Knee replacement surgery in North Wales is provided through Betsi Cadwaladr University Health Board (BCUHB), with orthopaedic services at Ysbyty Gwynedd (Bangor), Wrexham Maelor Hospital, and Glan Clwyd Hospital. Your GP can refer you to an orthopaedic surgeon for assessment.
Private options are also available at independent facilities across North Wales and the wider region, which may offer shorter waiting times and more choice over your surgical team.
Have questions about knee replacement? Contact us and we'll help point you in the right direction.