Unicompartmental Knee Arthroplasty

Unicompartmental knee replacement is a minimally invasive surgery in which only the damaged compartment of the knee is replaced with an implant. It is also called as partial knee replacement. The knee can be divided into three compartments: patellofemoral, the compartment in the front of the knee between the knee cap and thigh bone, medial compartment, on the inside portion of the knee, and lateral compartment which is the area on the outside portion of the knee joint.
Traditionally, total knee replacement was commonly indicated for severe osteoarthritis of the knee. In total knee replacement all worn out or damaged surfaces of the knee joint are removed and replaced with new artificial parts. Recently, partial knee replacement is used to relieve arthritis in one of the knee compartments.


The advantages of unicompartmental knee arthroplasty include:

  • Smaller operation
  • Smaller incision
  • Not as much bone removed
  • Shorter hospital stay
  • Shorter recovery period
  • Blood transfusion rarely required
  • Better movement in the knee
  • Feels more like a normal knee
  • Less need for physiotherapy
  • Able to be more active than after a total knee replacement


Surgery is performed under sterile conditions in the operating room under spinal or general anaesthesia. You will be on your back and a tourniquet applied to your upper thigh to reduce blood loss. Surgery will take approximately two hours. The Patient is positioned on the operating table and the leg prepped and draped. A tourniquet is applied to the upper thigh and the leg is prepared for the surgery with a sterilizing solution. An incision around 7 cm is made to expose the knee joint. Smaller incisions are made if the surgery is done using arthroscopy. The bone ends of the femur and tibia are prepared using a saw or a burr. Trial components are then inserted to make sure they fit properly. The real components (Femoral & Tibial) are then put into place with or without cement. The knee is then carefully closed and drains usually inserted, and the knee dressed and bandaged.
Usually you will remain in the hospital for 3-5 days. Depending on your needs, you will then return home or proceed to a rehabilitation facility. You will need physical therapy on your knee following surgery. You will be discharged on a walker or crutches and usually progress to a cane at six weeks. Your sutures are sometimes dissolvable but if not, are removed at approximately 10 days.

Risks and Complications

As with any major surgery, there are potential risks involved. Complications can be medical (general) or local complications specific to the Knee. The local complications include

  • Surgical site infection
  • Blood Clots (Deep Venous Thrombosis)
  • Fractures or Breaks in the Bone
  • Stiffness in the Knee
  • Wearing of implants
  • Wound Irritation or Breakdown
  • Cosmetic Appearance
  • Leg length inequality
  • Dislocation
  • Patella Problems
  • Ligament Injuries
  • Damage to Nerves and Blood Vessels

Discuss your concerns with your Orthopaedic Surgeon prior to surgery.