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Knee replacement surgery

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Overview of knee replacement surgery

Knee arthroplasty or knee replacement surgery is a procedure that replaces the weight-bearing surfaces of the knee joint. It relieves the pain and disability of osteoarthritis. It is also performed for other knee diseases like rheumatoid arthritis and psoriatic arthritis. This procedure is performed when the painful symptoms can no longer be controlled with non-operative treatments.


Types Knee replacement surgery

Knee replacement surgery is of two types:

  • Total knee replacement surgery

  • Partial knee replacement surgery

Total knee replacement surgery

This is a surgical procedure through which all the cartilage is removed from the knee joint, and is replaced with artificial material like metal and plastic implant.

Partial knee replacement surgery

This is a surgical procedure that involves a smaller incision and faster recovery than traditional total joint replacement surgery. The other names for partial knee replacement are ‘unicompartmental knee replacement' and 'minimally invasive knee surgery.' Through this procedure, only the most damaged areas of cartilage are removed and replaced. However, partial knee surgery is recommended for patients with arthritis confined to a limited area. It is not advised for patients with widespread arthritis.

Moreover it is recommended to patients belonging to the following groups:

  • Not obese
  • People with sedentary life style
  • Older than 55 years
  • People with intact ligaments


Benefits of partial knee replacement surgery

The benefits of partial knee replacement surgery are:

1) Smaller Incision: Traditional knee replacement surgery involves an incision of about 8 inches over the front of the knee, whereas the minimally invasive partial knee replacement involves an incision of about 3 inches.

2) Less Blood Loss

3) Shorter Recovery


Alternatives for Knee replacement surgery

The alternative non-operative treatment options are:

  • Weight Loss
  • Activity Modifications
  • Anti-Inflammatory Medications
  • Joint Supplements
  • Cortisone Injections
  • Hyaluronic Acid (e.g. Synvisc) Injections
The pre-operative preparation involves:
  • Surgical consultation
  • A range of hip, knee and ankle strengthening motion
  • Pre-operative tests like complete blood count, electrolytes, APTT and PT to measure blood clotting, chest X-rays, ECG, and blood cross-matching for possible transfusion
  • Intake of supplemental iron to boost the hemoglobin in the blood system
  • X-rays of the affected knee to measure the size of components
  • Medications like warfarin and aspirin are stopped few days before surgery to reduce the bleeding


Post-operative Rehabilitation of Knee replacement surgery

The post-operative rehabilitation involves hospitalization from one day to seven days on an average, depending on the health status of the patient. The patients are advised to use protected weight bearing on crutches or a walker till the quadriceps muscle gets healed and recovers its strength.

Moreover Continuous Passive Motion or CPM is commonly used. Some patients undergo physical and occupational therapy for several weeks to restore motion, strength, and function. Some patients recover within three months, while some requires many months longer than that.


The technique of knee replacement surgery involves the exposure of the front of the knee. This is achieved by detaching part of the quadriceps muscle (vastus medialis) from the patella, which is displaced to one side of the joint. The displacement of the patella exposes the distal end of the femur and the proximal end of the tibia. Using cutting guides oriented to the long axis of the bones, the ends of the tibia and femur are accurately cut to shape. Thereafter, the cartilages and the anterior cruciate ligament are removed. The posterior cruciate ligament may also be removed; however the tibial and fibular collateral ligaments are preserved. Then the metal or plastic components are impacted or fixed onto the bone using polymethylmethacrylate (PMMA) cement. Alternately, cement-less techniques may involve osseointegration, including porous metal prostheses.


Risks and complications of Knee replacement surgery

Risks and complications in knee replacement are similar to those associated with all joint replacements. The potential risks of knee replacement surgery are:

Deep Vein thrombosis:
Blood clots in the leg veins are the most common complication. However, periodic elevation of legs and lower leg exercises are used to increase circulation. Moreover, support stockings as well as medications are used to thin the blood.

A common risk among aging patients is periprosthetic fractures. These fractures may occur intraoperatively or postoperatively.

Loss of Motion:
At times the knee may not recover its normal range of motion, which is 0 - 135 degrees of rotation. Usually patients achieve 0 - 110 degrees. However, stiffness of the joint may occur.

A rare case of complication is the dislocation of the kneecap to the outer side of the knee. This is a very painful complication and usually requires surgery for the realignment of the kneecap. However, this is a rare complication.

Infection is a big concern for any type of surgery. The prosthetic infections are of four types:

  • Positive intraoperative culture
  • Early postoperative infection, which occurs within the first month of surgery
  • Acute hematogenous infection, which is the hematogenous seeding of a previously well-functioning prosthesis
  • Late chronic infection, which remains after one month of surgery


When to consult a doctor during post operation period

Medical advice should be taken immediately during post operation period if the following occurs:
  • Fever greater than 100 F (37.8 C)
  • Shaking chills
  • Drainage from the surgical site
  • Increasing redness, tenderness, swelling and pain in the knee

Written by: Healthplus24 team
Date last updated: September 30, 2012

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