Yorkshire Knee Surgery - Mr A Siddiqui Consultant Knee Surgeon
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Arthritis & Knee Replacement


  • The end result of many processes affecting the knee joint can be loss of joint cartilage with resulting pain, stiffness and deformity.
  • Usually affecting patients over 60 years of age, it can reach an advanced stage at an earlier age.
  • Some common causes include: Inflammatory (eg rheumatoid, psoriasis), crystal (gout), previous fractures or deformity of the bones, following meniscal removal, and simple old age.
  • Treatment is based on the stage of the condition, patients age and activities, and in a simplified form takes the form of a ladder starting with simple therapy and ending in major surgery.It can usually be seen on X-rays where a reduction in the gap between the two bones of the knee joint are seen.
X-ray showing severe arthritis in the knee joint

  • Loose bodies can sometimes form in arthritis or after damage or trauma to the knee joint. These move around the knee and sometimes cause jamming of the joint. They may or may not be seen on Xrays or scans. If accessible they can be removed by arthroscopy (keyhole surgery).
  • Activity modification, painkillers, walking sticks, physiotherapy, injections (steroid injections, viscosupplements such as synvisc, durolane, ostenil), and arthroscopic keyhole surgery combined with a washout, debridement [tidy up of joint surfaces], removal of loose bodies and osteophyte burring[removal of bony outgrowths] are some of the treatment methods with low complications and risks.
Knee Replacement is the final surgical remedy and may be partial for certain patterns of arthritis, or complete. It is a major procedure, and does carry some important risks (see below). It is a very successful procedure in the vast majority (98%).

Knee Replacement

This operation is done when the arthritis is very advanced and other appropriate therapies have failed. The worn out knee joint is replaced with a metal and plastic implant commonly cemented to the bones. This may be a partial (UKR) or full knee replacement (TKR), depending on the pattern of wear seen on X-rays, and symptoms experienced by the individual.

X-rays of a partial knee replacement on the left and in comparison a full or total knee replacement on the right


The procedure can now be done through less invasive exposures (Minimally Invasive TKR / MIS) than were previously used (average skin incision 10-12cm), and patients on average stay less than 5 days in hospital.

A video of a knee replacement using the minimally invasive technique can be viewed on this website and also at:



An animation video depicting a knee replacement along with some information about the procedure can be viewed at http://www.hipsknees.info/flash2/ypo.swf.The video is a 3rd party product and some aspects and information may differ from Mr Siddiqui's practice.

 Typical scar following a mini-incision knee replacement of 10cm.




Precise surgical technique is important for success. Experienced surgeons performing Knee replacements regularly and frequently often have superior results compared to less experienced and low volume surgeons. Mr Siddiqui carries out an average of 100 knee replacements per year. Implants in correct alignment survive for longer periods than those in mal-alignment. Average implant survival is 90% at 10-15 years.

Computer assisted surgery was developed to aid surgeons achieve accurate alignment of the knee replacement.

An audit of Knee Replacements performed by Mr Siddiqui revealed an accuracy in the alignment of the prosthesis comparable to computer assisted surgery. Average length of stay in hospital is now 3-4 days, with less than 5% needing blood transfusion from the blood bank. Autologous drains are used which allow the bleeding from the knee joint to be collected in a special system and returned to your body. Infection rate is under 1%. Infection of the prosthesis can occur many years after the procedure as bacteria can travel from one site in the body to another via the blood and other connecting channels. It is advisable to seek early treatment of any infection (eg) dental abscess, urinary tract infection, chest infection etc from your GP with prompt antibiotic therapy to reduce the risks of secondary infection once you have had a joint replacement.

Correction of the bow leg deformity with perfect alignment obtained after knee replacement



Implant technology is continually being updated and improved. New concepts in design continue to unfold and examples include a gender specific” implant, as a small proportion of female knees have anatomical differences that are better addressed with this particular implant , as well as a “High Flexion” implant that allows for a safe full knee bend post operatively in those who have a high degree of flexion pre-operatively. Both of these implants are currently utilised in suitable situations.

A video of a knee replacement performed by Mr Siddiqui can be seen on this website and also at:



Mr Siddiqui has been an instructor on the Minimally Invasive Knee Surgery and a variety of other training courses for surgeons. He has continued commitment in research in knee surgery, has many publications and follows the best practice guidelines published by the British Association of Knee Surgery UK of which he is a member. Mr Siddiqui uses the Nex-Gen Knee implants manufactured by Zimmer and the PFC knee implants manufactured by Depuy (Johnson and Johnson) for Total Knee Replacement. For Unicompartmental knee replacements, the Oxford UKR implants manufactured previously by Biomet but now part of Zimmer, are used.These implants all have excellent survivorship in Joint Registrys (databases of implants) from around the globe.
Special systems and implants are used when performing a "Revision Knee Replacement" in the event of failure of the original components. Bone is usually lost and sacrificed when the implant is revised and anchorage of the revision implant often needs supplementing with long stems on each component as shown below, and the situation is usually suboptimal when compared to "Primary Knee Replacement".

Sometimes the ligaments are dysfunctional and a more “constrained” implant may be utilised. Revision knee surgery can be technically challenging and can give rise to the same complications that exist for knee replacement, but the incidence and frequency of complications is somewhat higher.

A revision knee replacement


Complications of Knee Replacement

As with any major surgery, there are potential risks involved. The decision to proceed with the surgery is made because the advantages of surgery outweigh the potential disadvantages.
Complications can be medical (general) or local complications specific to the Knee. Medical complications include those of the anaesthetic and your general well being. Almost any medical condition can occur so this list is not complete.

General and anaesthetic related complications include
- Allergic reactions to medications
- Blood loss requiring transfusion with its low risk of disease transmission
- Heart attacks, strokes, kidney failure, pneumonia/chest infection, bladder infections.
- Swelling of legs and ankles due to lack of mobility and fluid retention.
- Complications from nerve blocks and epidurals such as infection or nerve damage.
- Inability to pass urine requiring catheterisation.
- Serious medical problems can lead to ongoing health concerns, prolonged hospitalization or rarely death.
Infection can occur with any operation. In the knee this can be superficial or deep. Infection rates vary but average 1%. If it occurs it can be treated with antibiotics but may require further surgery. Very rarely your new knee may need to be removed to eradicate infection. A revision knee replacement may follow after about 6-8 weeks if there is no further evidence of infection persisting. In extremely rare cases amputation can result.
Blood clots (Deep Venous Thrombosis)
These can form in the calf muscles and can travel to the lung (Pulmonary embolism). These can occasionally be serious and even life threatening. A blood thinning agent is usually administered, but can cause the opposite problem of excessive bleeding and swelling leading to an increased risk of infection. If excessive swelling or prolonged discharge from the wound persists (beyond 48 hours) then the blood thinner may need to be discontinued.
The Range of movement in general mirrors the range of movement prior to the operation. During surgery contractures and obstructions to movement are dealt with and range of movement may improve after the knee replacement on account of this, however it will require a lot of effort and stretching manoeuvres and after 3 months becomes significantly harder to improve. Occasionally due to excessive scar tissue formation due to an inherent tendency in patients to scar (rare condition called arthrofibrosis) movement may be quite poor and resistant to improvement. The average range after knee replacement in Mr Siddiqui’s series is full extension (straight) to 115 degrees bend.
Wear and loosening
The plastic liner wears out over time. The implant may start to loosen and in the process some bone resorption may take place leading to eventual failure of the prosthesis with the possibility of a revision procedure which is rarely if ever as good as the index procedure. 90% of TKRs are still functional at 10-15 years.
Wound problems
The operation will always cut some skin nerves, so you will inevitably have some numbness on the outer aspect of the wound. This does not affect the function of your joint. You can also get some aching around the scar. Vitamin E cream and massaging can help reduce this. Occasionally, you can get reactions to the sutures, dressings or a wound breakdown which may require antibiotics or further surgery.
An extremely rare condition where the ends of the knee joint loose contact with each other or the kneecap jumps in and out of the groove.
Ligament injuries
There are a number of ligaments surrounding the knee. These ligaments can be injured during surgery or at any time afterwards.
Damage to nerves and Blood vessels
Rarely these can be damaged at the time of surgery. If recognized they are repaired but a second operation may be required. Nerve damage can cause a loss of feeling or movement below the knee and can be permanent.
Fractures or breaks in the bone can occur during surgery or afterwards if you fall. To fix these, you may require surgery which is very major and mobility may never be quite the same after this catastrophe.
Knee Replacement aims to reduce pain significantly from the arthritic pain, but it is not unusual to find some residual pain in the knee after an otherwise successful procedure. This sometimes originates from other areas of the body such as the hip joint or the spine and treatment depends on the nature of the condition in these areas, or sometimes no definite cause can be found. It is not usually comfortable kneeling after a knee replacement and some patients find it very difficult to kneel afterwards.

External Links providing useful information on Knee Replacements and treatments for arthritis: