Knee Replacement Surgery

Knee replacement surgery is a procedure in which parts of the knee joint are removed and replaced with a prosthetic knee replacement system or components.  The surgery is performed when other methods of treatment fail to relieve pain and disability due to damage, disease, or wear on some or the entire knee joint.  Although knee replacement surgery often requires a long recovery and carries risks, most recipients report an increase in their quality of life following the procedure, and prosthetic knees can last up to 20 years.

Medical conditions leading to knee replacement surgery

Because of the risks and lengthy recovery period involved in knee replacement surgery, it is usually only considered as a last option.

Knee replacement surgery is recommended if you have one or more of the following symptoms:

• severe pain, swelling and stiffness in your knee joint, even when at rest
• limited mobility in knee joint
• knee pain is so severe that it interferes with your quality of life
• everyday tasks, such as shopping or getting out of the bath, are difficult or impossible
• feelings of depression because of the pain and reduced mobility
• you cannot work or have a normal social life

Medical conditions that can cause the above symptoms include:

• knee injury
• knee deformity
• osteoarthritis – general damage to joints
• rheumatoid arthritis -damage to joints caused by an autoimmune reaction
• haemophilia – a genetic condition that causes joint bleeding, pain, and damage
• gout – damage to joints caused by a buildup of certain chemicals in the blood
• bone dysplasia – a disorder that causes unusual bone growth
• avascular necrosis – death of bone in the knee joint following blood supply problems

Types of knee replacement surgery

The knee joint consists of three compartments or weight-bearing surfaces where two bones meet.  These compartments contain soft tissues called articular cartilage that pad the bones and prevent them from rubbing against each other.  The thigh bone (femur) and shin bone (tibia) are connected by the medial and lateral compartments, which sit side by side in the knee.  The thigh bone and kneecap are connected by the patellofemoral compartment.

Depending on the extent of the damage to the knee, as well as the age, lifestyle, and overall health of the patient, and the expected course of the underlying condition – surgeons may replace one, two, or all three of the compartments with prosthetic components.

These knee replacement procedures are known as:

• Total knee replacement (TKR), or total knee arthroplasty, where doctors replace the medial and lateral compartments.  Surgeons may also replace the patellofemoral compartment during TKR.
• Partial knee replacement (PKR), or partial knee arthroplasty, a procedure where either the medial or lateral compartment is replaced.  Surgeons may also replace the patellofemoral compartment during PKR.
• Patellofemoral replacement, or patellofemoral joint arthroplasty, is when a surgeon replaces only the patellofemoral compartment.
• Unicompartmental knee replacement (UKR) is where either the medial or lateral compartment is replaced.
• Bicompartmental knee replacement involves replacing two of the three compartments.

Surgical procedures and components

The knee replacement surgery itself requires removing the damaged parts of the bone and replacing them with metal or other synthetic components.  Plastic inserts are then added to take the place of the articular cartilage and prevent the metal components from grinding against one another.  The surgery is done under general or epidural anesthesia and usually takes one to three hours.

Partial knee replacement is a smaller operation, allowing for a smaller incision, less bone removal, and a shorter recovery time than total knee replacement.  However, partial knee replacement may not resolve joint pain as well, is less durable than total knee replacement, and is not suitable for younger, more active patients.

Total knee replacement (TKR) involves attaching a curved metal plate to the end of the femur, and a flat plate at the end of the tibia, with a plastic spacer between them.  PKR uses smaller metal implants.  In the case of a palletofemoral replacement, a metal plate is added to the front of the femur and either the back of the patella is resurfaced with another metal plate, or the entire patella is replaced.

Prosthetic knee components and total knee replacements are manufactured by companies like Biomet, DePuy, Smith and Nephew, Stryker, and Zimmer.  Because of the dangers and side effects that can arise from product design or defective medical devices, doctors and patients should carefully research the manufacturer of any components they consider using to find out if there have been any product recalls, FDA warnings, or lawsuits involving the device they are considering.

Patients should also be careful to follow their surgeon’s instructions before, during and after their hospitalization in order to minimize complications.  Some knee replacement complications can be serious and require subsequent surgeries to correct.

The following complications can occur during or after knee replacement surgery:

• infection in the wound or within the joint
• unexpected bleeding into the knee joint
• damage to local ligaments or arteries
• nerve damage around the joint, resulting in numbness or weakness
• blood clots, deep vein thrombosis, pulmonary embolism
• fracture during or after surgery
• excess bone growth after surgery
• scarring
• kneecap dislocation
• numbness around the wound scar
• allergic reaction
• joint instability
• need for premature knee revision surgery

Advances in knee replacement surgery

Several advances have been made in knee replacement surgery which allow for less invasive and/or more accurate procedures.  Some examples are:

• Mini-incision surgery (MIS) – A smaller cut is made and special equipment is used to maneuver around muscles and tendons that would be cut during a regular surgery.
• Image-guided surgery – This surgery is performed using computer-generated images made from infrared beacons attached to parts of your leg and some of the operating tools.  The procedure requires special equipment that is not available in most facilities, but may offer a more accurate positioning that will minimize later complications.
• Patient-specific knee replacement – The implant is selected and fitted using a special alignment guide created by taking MRIs of the patient’s knee.  This allows for a more accurate fit.

Recovery from knee surgery

Recovery from knee surgery can be a long process and is not without risk of knee replacement complications, but can be expedited by following post-operative advice and instructions regarding rehabilitation.  Minimally invasive surgery may be performed in one day, while more extensive procedures may require hospitalization for over a week. Your surgeon will provide you with care information, antibiotics, painkillers, and a prescribed course of physical therapy to help you recover.

Most patients should be able to walk without crutches or a walking frame after about six weeks.  Pain and swelling may continue for up to three months, and it may be up to two years before full muscular strength and range of motion is restored in the joint.  Patients are advised to avoid high-impact or high-risk sports even after recovery.

Need for revision surgery

In some situations, a defective knee replacement that leads to extensive problems may necessitate revision surgery. This second operation puts patients at more risks for complications. Injured recipients may choose to file lawsuits against manufacturers of faulty knee replacements in an attempt to recover damages for their medical expenses, lost wages and pain and suffering.