Total Knee Replacement

Introduction

Total knee arthroplasty (TKA) has been the standard operative procedure for reliably diminishing or relieving pain, correcting deformity and restoring function in patients with osteoarthritis or rheumatoid arthritis. TKA replaces those worn surfaces with plastic and metal.

The femur replacement is a smooth metal component which fits snugly over the cut end of the femoral bone. The tibial component is in two pieces; a stemmed metal base plate that is fitted to the bone and a hard-plastic bearing surface that rotates onto the base plate. The patella may be replaced or resurfaced with a hard-plastic dome.

This is a rotating-platform knee replacement and is the preferred prosthesis used by Dr Lane. It allows low contact stress and low constraint force to improve wear resistance and theoretically, minimise loosening. It also offers self-adjustment to accommodate surgical mal-alignment.

The latest studies have shown that up to 20% of patients have some residual symptoms and discomfort in the knee even though the severity of the pain has been dramatically reduced. Many patients notice a clicking sensation in the knee that may diminish in time. It is important that the patient has realistic expectation concerning what can be achieved.

Indications for knee replacement surgery

  • The knee joint is severely damaged by arthritis. This occurs with osteoarthritis and also with rheumatoid arthritis. The weight bearing surface (cartilage) of the knee is worn away, bone on the femur eventually grinds on the tibia. Bony spurs also begin to form and the knee becomes deformed and sometimes mal-aligned. The kneecap can also be involved.
  • Significant pain, especially at night.
  • Reduced ability to perform simple daily activities.
  • Walking limited to short distances.

Peri-operative Patient Education

At the time of consultation, Dr Lane will give a full explanation of what is involved in a joint replacement operation, expected recovery and eventual outcomes.

The following guide further informs the patient. Educational leaflets supplied by the Australian Orthopaedic Association are also supplied. The patient is asked to attend the pre-admission clinic at the hospital, (Sunshine Coast Private Hospital, Buderim or the Sunshine Coast University Hospital, Birtinya). There the patient will see experienced nurses and physiotherapists who will discuss the pre- and post-operative course. This increased knowledge of events leads to a less stressful recovery.

If you have a pre-existing medical condition you may be reviewed by further specialists such as a cardiologist or other specialised physicians, and anaesthetist prior to surgery.

If there are any further concerns the staff at Lake Kawana Specialist Centre are happy to take calls and if needed, a further explanation is encouraged by nursing staff, anaesthetist or Dr Lane.

Pre-operative Instructions

Anti-inflammatory drugs such as Feldene, Naprosyn, Brufen, Indocid, Voltaren, Mobic, and Celebrex should be stopped 5 days before surgery. These drugs may increase the risk of bleeding. Aspirin or other blood-thinning drug use prior to the surgery should be discussed with Dr Lane as this would depend on the patients underlying medical condition. The leg to be operated on should be free of any cuts, scratches and sores as this can increase the risk of infection. If you have any damage to the skin your surgery will be postponed until healed. At the pre-admission clinic, you will be given an anti-septic skin wash to use in the shower the day before admission. Pre-operative investigations are performed which include blood tests, cross matching for blood, ECG, CXR and urinalysis.

Dr Lane will see you in his rooms a few days before surgery to check your skin and answer any other questions you may have.

Depending on the time of your operation, you may be admitted the day before or early in the morning of procedure. Your expected stay in hospital is 3 to 7 days.

You should not eat or drink 6 hours before your surgery.

Bring to hospital:

  • Personal effects such as Pyjamas, slippers, dressing gown and toiletries.
  • Current medication.
  • Relevant X-rays.
  • Medicare and Private Health Care cards.

You will be seen at the Admissions area and taken to the Ward:

  • You will have a shower with an anti-septic solution.
  • Theatre gown and disposable underwear given to wear.
  • The leg will be inspected and dressed with an anti-septic solution and a sterile drape.
  • The other leg will have a TED stocking applied to reduce the risk of thrombosis following surgery.

You will be taken into the theatre complex by the nursing staff and then into the anaesthetic bay next to the operating room. There you will meet Dr Lane and your anaesthetist.

The anaesthetist will tailor the type of anaesthetic to your needs. This may involve a general anaesthetic (when you are completely asleep) or a local regional block (spinal or epidural using a needle into the lower back) which numbs the legs, used with twilight sedation. Post-operatively, you will receive narcotic type drugs for pain relief which may be delivered by PCA (Patient Controlled Analgesia) combined with other pain killers and anti-inflammatory medication. Intravenous antibiotics will be infused prior to surgery and continued for 24 hours to reduce the risk of infection. Intra venous fluids to keep you hydrated in theatre will commence.

Procedure

The procedure itself takes about 90 to 120 minutes but you may spend up to 3 hours in the theatre complex- time included in the anaesthetic bay preparing for theatre and in recovery.

You will be taken into the theatre room and placed on the operating table lying on your back. A tourniquet is no longer used in knee replacements. The tourniquet was intended to give a bloodless field for surgery, but its use was associated with increased postoperative pain and swelling. TKA can have substantial peri-operative blood loss rendering the patient at risk of allogenic blood transfusion. Dr Lane administers intravenous tranexamic acid to his patient’s immediately prior surgery as this has been shown to reduce bleeding during the operation. Tranexamic acid is an anti-fibrinolytic or “blood clot stabiliser” whose mechanism of action reduces bleeding. Your X-rays will be displayed in theatre for Dr Lane’s reference.

Prior surgery, catheter is inserted into your bladder to prevent any problems with the bladder post-operatively. This is usually removed the following day.

An incision is made over the front of your knee measuring about 15 to 20cms in length. Care is taken to make sure that major vessels and nerves around the knee joint are protected. The knee joint is opened. Contracted soft tissue, bony spurs, remnants of menisci and cruciate ligaments are removed. *Software navigation pins are applied to the knee and registration is formalised*.

Very accurate jigs are then used to cut the bones to fashion a perfect fit for the new components. Trial components are placed in the cut knee bones. This ensures that the prosthesis is placed in the correct alignment and that the knee bends smoothly and is balanced before the real knee components are put in place.

The tibial component made of a stemmed metal (cobalt chrome alloy) base is usually put in place un-cemented. The stem has a titanium hydroxyl-apatite outer coat to encourage bony in-growth. There is no significant difference in results using un- cemented or cemented components. The tibial component transfers forces to the tibial bone evenly from the knee replacement. Dr Lane may cement the tibial component if the bone is very soft which occurs in about 10% of replacements. The tibial component has a highly cross-linked, polyethylene rotating platform placed on the bearing surface. 

The femoral component is comprised of a highly-polished metal (cobalt chrome alloy) on the bearing surface. The under surface is comprised of a titanium and hydroxyl-apatite coat which encourages bony in-growth and is positioned un-cemented over the cut femur. It replaces the original shape of the femur in the pre-arthritic condition.

The patella is assessed at the time of surgery. If the patella is being replaced, the bearing surface is fashioned to fit patella shaped, highly cross-linked polyethylene plastic.

There are a number of designs of knee prosthesis available in Australia but so far there has not been a significant difference in long-term performances of the better performing prosthesis. Dr Lane uses the “LCS” components. It is regarded as one of the better performing prosthesis as shown in the Australian Joint Replacement Registry.

The knee is checked again to make sure that the function is smooth and stable.

A reperfusion drain is inserted around the joint, the capsule and soft tissues around the joint repaired and skin closed with staples.

A wound is covered with a sterile dressing and then knee bandaged securing the drain. The leg is put in a knee splint.

*Dr Lane uses the BrainLab  “Knee 3” software guided knee surgical navigation. This new computer software takes a different approach to addressing the current challenge of total knee replacement prosthetic alignment. It aids the surgeon to visualise more accurately joint stability over the full range of motion of the knee joint before any resection is made. Software guided surgical navigation has been shown to improve prosthetic alignment, reduce revision and improve outcome.*

Post-operative Instructions

In Hospital

You will be taken into recovery by the anaesthetist and nurse. Your blood pressures, pulse rate and breathing will be monitored. Sensation and circulation of your limbs are checked by the nurse. Once you are stable and comfortable you will be taken back to the ward.

  • Intravenous fluids will be continued on the ward until you are able to eat and drink adequately.
  • For the first 24 hours, post-operatively the patient will be fitted with foot pumps and TED stockings. TEDs (tight stockings) should be worn for six weeks from the time of surgery. These measures reduce the risk of DVT. Aspirin or other blood thinners will be prescribed. If there is a high risk if thrombosis (e.g. previous blood clots), further anti-clotting agents will be prescribed. Patients are encouraged to get out of bed on the day of surgery. Moving early after surgery is the most effective way of diminishing the risk of DVT and pulmonary embolus.
  • The anaesthetist will keep a close eye on your pain relief and will endeavour to keep you comfortable. This is often initially with morphine like drugs delivered by use of PCA (patient controlled analgesia). These drugs can cause drowsiness and nausea which can be addressed.
  • Dr Lane will discuss the operation with you and review you while you are in hospital. A copy of the operative notes will be sent to your GP.
  • Your blood level will be checked the following day and X-Rays taken to check the position of your knee components.
  • A physiotherapist will see you soon after your surgery to look after your mobility and give you a series of exercises to aid muscle strength and get you back on your feet.
  • You will be ready to leave hospital once you can bend your knee to 90 degrees, can get in and out of bed un-assisted, access the toilet and shower, walk about 30 metres on your own and can get up and down stairs. Walking aids such as crutches or a frame will be used initially, but patients are encouraged to discard them once they are able to walk comfortably without a limp.
  • There will be significant swelling and sensation of warmth in the knee that lasts for several weeks.
  • The knee will be sore after surgery despite the pain- relieving medication. It is important to continue exercising to obtain good quadriceps function and knee bending and work through the pain.
  • Most patients are able to go home between 4 and 6 days. You will be sent home with pain killers and will continue to have physiotherapy for 6 to 12 weeks depending on your progress. Patients who live alone or have other medical conditions may need inpatient rehabilitation which can be arranged locally.
  • An appointment will be made to see Dr Lane 6 weeks after surgery. However, if there are problems with movement, swelling or pain at control at home, you are encouraged to contact Dr Lane.

At Home

It is expected that you will have mild to moderate pain on returning home. The pain is managed using oral narcotic analgesia such as endone and then panadeine forte. Movement, swelling and pain should all improve over the next 6 to 12 weeks.
The Blue nurse will remove your staples 10 to 14 days after surgery.

Latest studies have shown that 20% of patients have some ongoing symptoms and discomfort in the knee even though the pain has been drastically reduced. It is important to acknowledge that the knee doesn’t feel like a new knee. It often clicks with movement and weight bearing. Often patients are unable to kneel on their replaced knee or squat. There is usually a numb patch of skin over the knee which is permanent due to small nerves that were cut at the time of the incision.

After the operation, the knee should have a range of movement to 100 – 120 degrees although some can obtain a greater range. This enables the patient to return to recreational activities such as walking, cycling, swimming, golf, driving, and ballroom dancing. However, it is imported not to over-stress or load up the knee as this will accelerate the wear of the knee components. Activities such as jogging, aerobics, skiing, tennis and hiking should be avoided.

About 10 % of knee replacements require revision at 10 years. Knee revisions are technically more difficult, have more complications and less successful outcome than original surgery.

It is important to treat infections such as dental, diverticular and urinary tract infections aggressively. Surgical procedures such as dental extractions, bladder catheterisation and colonoscopies should be covered with antibiotics so it is important to inform your doctor that you have a knee replacement beforehand. Infection of the knee replacement is difficult to eradicate and may require staged complex surgery and result without a knee joint or a shortened, painful leg.

Risks 

General risks associated with Anaesthetic

During surgery, your body is stressed and pre-existing conditions such as heart, respiratory and circulatory conditions may worsen.

  • Death (rare)
  • Myocardial infarction (heart attack) and cardiac arrhythmia.
  • Stroke.

These events are uncommon:

  • Pneumonia (lung infection).
  • Short term confusion.
  • Deep venous thrombosis (blood clots). These occur in legs but can rarely break off and travel to lungs (pulmonary embolus). This can be potentially fatal.
  • Bladder and prostrate problems. A catheter is placed in the bladder prior theatre to avoid this.
  • The bowel may become paralysed after surgery which causes bloating, pain, nausea and vomiting for a few days.

Local risks

These events are uncommon:

  • Infection. Superficial infection is not common and usually responds to antibiotics. Deeper infections can occur at any time, is rare but has serious consequences. Infection often requires difficult staged revision knee replacement. Sometimes revision surgery is not possible and the knee needs to be fused or surgically stiffened. Extremely rarely amputation may be required.
  • Bleeding may occur for several days following surgery.
  • Knee stiffness. A small proportion of patients need to be returned to theatre in the first 3 months for knee manipulation to help the knee bend.
  • Knee pain and stiffness following surgery. Sometimes the cause is not clear.
  • Rarely the patient may develop a painful, swollen red and stiff knee with abnormal sensation. This is due to an abnormal nerve condition that can develop and is difficult to treat.
  • Foot drop. Nerves around the knee can be injured.
  • Occasionally fracture of tibia or femur around the knee components. This is usually recognised at the time of surgery and can be corrected but does delay recovery.
  • The new joint may loosen or wear over time and may require revision surgery.

Patients with diabetes, obesity, pre-existing multiple medical conditions, patients with advanced age and frailty, and smokers will have an increased risk of adverse complications.