Knee replacement surgeon London

Medically reviewed by Sam Rajaratnam FRCS (Tr. & Ortho).

Knee Replacement Procedure for Osteoarthritis of the Knee

A talk on enhanced recovery in joint replacement surgery

Osteoarthritis of the knee is a very common cause of knee pain, often bringing with it the feeling of the knee giving way and swelling.

Whilst conservative treatment including painkillers, steroid or cartilage protein injections and physiotherapy can be helpful in the early stages, most people with osteoarthritis of the knee will eventually require knee replacement surgery.

Depending on which part of the knee is worn will determine the types of symptoms an individual will feel, be that pain, locking, giving way or stiffness.

What does knee replacement surgery involve?

Knee replacement surgery has advanced tremendously over the last 30 years and is now one of the most successful operations performed throughout the world. The National Joint Registry recorded 102,177 primary knee joint replacement procedures performed in England in 2017.  

In years gone by, the replacement itself formed a hinge to the knee joint, but modern knee replacements are surface replacements only.  They work by removing the arthritic surface of the knee and capping it with an artificial surface. It is custom-fitted to the patient’s anatomy by an expert surgeon.

Modern high flexion knee replacements allow a pain free and active life

Modern high flexion knee replacements allow a pain free and active life

Modern high-flexion knee replacement design allows an excellent range of motion once the patient has fully recovered.  Most patients are able to mobilise safely and be discharged home within a couple of days of their joint replacement.

It is very important that the patient continues to exercise their knee after discharge home. The overall patient satisfaction rate of a successful joint replacement with a rapid recovery programme is in the region of 94%, with the majority of patients being able to walk long distances, play golf, cycle, swim and lead an active lifestyle and a life without pain. Knee replacements are also lasting longer as per the National Joint Registry with the majority exceeding 15 – 20 years.

Partial vs Total Knee Replacement Surgery.

Osteoarthritis can affect either one part of the knee or multiple areas within the joint. In some instances your surgeon may recommend a partial knee replacement as a solution for your knee pain and condition.

As implant technology has developed, and the designs and results of full knee resurfacing have improved, many patients choose to have the whole joint resurfaced as the outcomes and function post knee replacement/resurfacing give them an extremely reliable outcome.

Mr. Rajaratnam is known nationally for his excellent outcomes as seen in the UK National Joint registry and undertakes one of the highest number of joint replacements annually in the UK.

He is passionate about achieving the best possible outcome following joint resurfacing/replacement procedures, and has pioneered many rapid and enhanced recovery programmes to achieve this.  He also believes that meticulous soft tissue handling and careful surgical technique can dramatically reduce complications and infections, as evidenced by his excellent results in the National Joint Registry.

Computer Assisted Alignment vs Conventional Alignment

Computer assisted alignment

Computer assisted alignment

The accurate alignment of joint replacement is vital to achieving excellent function post knee replacement surgery, since malpositioning of knee replacement components could lead to early failure and the necessity for revision surgery.

Conventional knee replacement surgery, without the aid of computer technology, uses analogue measuring devices and x-ray (radiography) imaging preoperatively to assist in sizing components and making decisions on the cuts to the bone and the positioning of implants during the operation. A number of instruments are employed to position guides so that the damaged bone and cartilage can be removed from the joint. Sometimes instruments are located inside the femur and/or the tibia to help with the positioning and alignment of the implant. Since the alignments and bone cuts have to be made in a three dimensional plane, the two dimensional radiographs have to be interpreted with great accuracy. These conventional methods of alignment have improved greatly with the use and improvements of mechanical alignment instruments, and are still widely used for knee replacement surgery.

Latterly computer imaging has been used to produce customised patient instrumentation. This makes use of MRI (magnetic resonance imaging) or CT (computed tomography) technology to obtain unique positioning guides for the knee replacement surgery, the so called ‘Patient Specific Instrumentation’ (PSI). The Zimmer Biomet versions of PSI is called ‘Signature’, and can be used with both the ‘Persona’ and ‘Vanguard’ knee replacement systems. The MRI scan, which only takes about 20 minutes, will only include your hip, knee and ankle. The scan is done so that your knee joint and leg alignment can be studied in precise detail. The reason for this is to further aid the surgical procedure including the alignment process and the positioning of the implants. With computer assisted knee replacement surgery there is potentially less need for invasive procedures to the femoral and tibial medullary canal for insertion of guides, and potentially fewer instruments are needed.

A number of scientific studies have found that computer assisted alignment is the more accurate method for aligning the implants. The MRI produces a three dimensional image which is unique to your anatomy, and allows the surgeon to plan preoperatively in a very effective way. Computers can manipulate MRI scans in a software programme to produce a virtual three dimensional image of your knee and leg alignment.

The MRI scan, because it  provides a great level of detail about your knee joint, gives the surgeon more information about the component sizing, alignment and positioning that is right for you. Sometimes it will be used to provide information about the way the custom-fitted implant will be formed and the instruments to be used.


The early knee joint replacement implants were quite simply hinges, but these tended to fail because they didn’t take into account the rotation of the knee joint. The modern designs, however, are not hinged and are designed to replace only the damaged surfaces of the bones of the joint rather than the whole joint.

There are a number of commercial companies which make knee replacement implants and systems including DePuy, Stryker, Zimmer Biomet, Smith & Nephew and ConforMIS, and these are manufactured in different styles, options and materials.

Mr. Rajaratnam can talk you through the various pros and cons of each design philosophy.

Mr. Rajaratnam generally favours the ‘Persona’ and ‘Vanguard’ knee system (from Zimmer Biomet) with the potential additional use of the 3D printed MRI assisted ‘Signature’ jigs (based on MRI modelling of the patient’s own anatomy), but in many instances, patients may chose to use the conventional alignment methods, which will still give them an excellent outcome.

It is exceptionally important to know an implant company’s manufacturing track record before choosing an implant. There are approximately 100 different knee replacement systems on the world  market, but a few giant companies manufacture the vast majority of the implants, and generally provide trustworthy and long lasting products.

Zimmer Biomet produce almost half of all the knee replacement implants made in the world, and have an excellent manufacturing history over the last 40 years in knee replacement design.

The ‘Persona’ is their latest high flexion knee design, and is possibly the most comprehensive knee replacement system on the market today.

Knee replacement surgery recovery – Enhanced recovery programme

As techniques and processes have developed, expert centres throughout the UK have seen improved results of modern knee replacement through the enhanced recovery programme.  

Best results are gained by careful surgery and a streamlined approach to pre and post operative rehabilitation.

This involves:

  • A comprehensive preoperative meeting with a consultant who specialises in knee surgery to help with the patient’s understanding of the process.
  • Excellent verbal and written information to ensure the patient is fully prepared.
  • Optimising the patient’s health and fitness prior to surgery i.e. nutritional state, exercise programme and minimising any medical conditions.
  • Use of the latest high-flexion knee implants during surgery which have a proven track record.
  • Care from an expert theatre team who implant hundreds of knee replacements annually with excellent results.
  • Use of an advanced spinal and local anaesthetic technique to optimise pain control after surgery.
  • A co-ordinated postoperative early rehabilitation programme, involving the surgeon, nurses and physiotherapists.
  • Most importantly a motivated patient who is keen to exercise their knee, following a knee resurfacing/replacement procedure, as this will give the best outcome after surgery.

Knee exercises after knee replacement surgery

Mr.Rajaratnam focuses on achieving excellent function after knee replacement surgery. The keys for achieving full functional recovery are accelerated rehabilitation and targeted physiotherapy.

The surgeon, anaesthetist, surgical care practitioners, physiotherapists and dedicated nurses work as a team to make patients comfortable post surgery.

Generally you will be able to move your knee as early as 30 minutes following joint replacement surgery.

Patients are encouraged to walk with our highly trained physiotherapists and nurses within 3-4 hours.

Joint replacement patients usually remain in hospital for 2-3 days and will have safely walked up and down stairs before being discharged home.

Over the next 2 weeks, achieving an excellent range of movement in the knee is key, and you will be taught how to bend and straighten your knee in order to achieve this.

You will be seen 2 weeks post surgery for a follow up appointment.

Once the wound has healed and a full range of movement has been achieved, it is important to strengthen the muscles around the knee.

The aim of the exercises is to increase muscle tone around the new knee joint.

We are happy to recommend a specialist knee physiotherapist who will arrange to see you as an outpatient, oversee your strengthening programme and monitor your progress over the next few weeks.

If you already have a good physiotherapist, we are happy to work collaboratively with him/her during your rehabilitation.

Ultimately a full pain-free range of movement in your knee with good muscular recovery will enable you to return to an active lifestyle.

FAQs about Knee Replacement Surgery

Should I be worried if my replacement knee is clicking?

If you have had a knee replacement before and it is now clicking, you may first want to read our article here: