Partial Knee Replacement

Disease Overview of Arthritis

Unicompartmental Knee Replacement

Arthritis is inflammation of a joint causing pain, swelling (inflammation), and stiffness.

Osteoarthritis is the most common form of knee arthritis in which the joint cartilage gradually wears away. It most often affects older people. In a normal joint, articular cartilage allows for smooth movement within the joint, where as in an arthritic knee the cartilage itself becomes thinner or completely absent. In addition, the bones become thicker around the edges of the joint and may form bony “spurs”. These factors can cause pain and restricted range of motion in the joint.

Causes of Arthritis

The exact cause is unknown, however, there are several factors that are commonly associated with the onset of arthritis and may include:

  • Injury or trauma to the joint
  • Fractures of the knee joint
  • Increased body weight
  • Repetitive overuse
  • Joint infection
  • Inflammation of the joint
  • Connective tissue disorders

Symptoms of Arthritis

Arthritis of the knees can cause knee pain, which may increase after activities such as walking, stair climbing or kneeling.

The joint may become stiff and swollen, limiting the range of motion. Knee deformities such as knock-knees and bow-legs may also occur.

Diagnosis of Arthritis

Your doctor will diagnose osteoarthritis based on the medical history, physical examination, and X-rays.

X-rays typically show a narrowing of joint space in the arthritic knee.

What is Unicompartmental Knee Replacement?

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 a partial knee replacement.

The knee can be divided into three compartments: patellofemoral, the compartment in front of the knee between the kneecap and thighbone, medial compartment, on the inside portion of the knee, and lateral compartment which is the area on the outside portion of the knee joint.

Indications of Unicompartmental Knee Replacement

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. Partial knee replacement is a surgical option if your arthritis is confined to a single compartment of your knee.

Surgical Procedure of Unicompartmental Knee Replacement

Your doctor may recommend surgery if non-surgical treatment options such as medications, injections and physical therapy have failed to relieve the symptoms.

During the surgery, a small incision is made over the knee to expose the knee joint. Your surgeon will remove only the damaged part of the meniscus and place the implant into the bone by slightly shaping the shinbone and the thighbone. The plastic component is placed into the new prepared area and is secured with bone cement. Now the damaged part of the femur or thighbone is removed to accommodate the new metal component which is fixed in place using bone cement. Once the femoral and tibial components are fixed in proper place the knee is taken through a range of movements. The muscles and tendons are then repaired and the incision is closed.

Post-operative Care Following Unicompartmental Knee Replacement

  • You may walk with the help of a walker or cane for the first 1-2 weeks after surgery. A physical therapist will advise you on an exercise program to follow for 4 to 6 months to help maintain range of motion and restore your strength. You may perform exercises such as walking, swimming and biking but high impact activities such as jogging should be avoided.

Risks and Complications Following Surgery for Unicompartmental Knee Replacement

Possible risks and complications associated with unicompartmental knee replacement include:

  • Knee stiffness
  • Infection
  • Blood clots (Deep vein thrombosis)
  • Nerve and blood vessel damage
  • Ligament injuries
  • Patella (kneecap) dislocation
  • Plastic liner wears out
  • Loosening of the implant

Advantages of Unicompartmental Knee Replacement

The advantages of Unicompartmental Knee Replacement over Total Knee Replacement include:

  • Smaller incision
  • Less blood loss
  • Quick recovery
  • Less post-operative pain
  • Better overall range of motion
  • Feels more like a natural knee

Mako Robotic-Arm Assisted Technology for partial knee replacement

Mako Robotic-Arm Assisted Technology for partial knee replacement

We understand that making sure you know what to expect from your joint replacement experience is important to you. As you are reading through this material, if you have additional questions please reach out to us to discuss.

Each patient is unique, and can experience joint pain for different reasons. It’s important to talk to us about the reason for your knee pain so you can understand the treatment options available to you. Pain from arthritis and joint degeneration can be constant or come and go, occur with movement or after a period of rest, or be located in one spot or many parts of the body. It is common for patients to try medication and other conservative treatments to treat their knee pain. If you haven’t experienced adequate relief with those treatment options, you may be a candidate for Mako Partial Knee replacement, which may provide you with relief from your knee pain.

How Mako Technology works

Mako Robotic-Arm Assisted Technology provides you with a personalized surgical plan based on your unique anatomy. First, a CT scan of the diseased knee joint is taken. This CT scan is uploaded into the Mako System software, where a 3D model of your knee is created. This 3D model is used to pre-plan and assist your surgeon in performing your partial knee replacement.

In the operating room, your surgeon follows your personalized surgical plan while preparing the bone for the implant. The surgeon guides the robotic-arm within the pre-defined area and the Mako System. The surgeon guides the robotic-arm within the pre-defined area and the Mako System helps the surgeon stay within the planned boundaries that were defined when the personalized pre-operative plan was created. This helps to provide more accurate placement and alignment of your implant.1

  • Mako Robotic-Arm Assisted partial knee replacement is a treatment option for adults living with early to mid-stage osteoarthritis (OA) that has not yet progressed to all three compartments of the knee. Depending on where the arthritis affects the knee, patients may have an implant inserted in any of the following areas:

Step 1. Knee CT Scan

Step 2. Knee Personalized Planning

It’s important to understand that the surgery is performed by an orthopaedic surgeon, who guides the robotic-arm during the surgery to position the implant in the knee joint. The Mako Robotic-Arm does not perform surgery, make decisions on its own, or move without the surgeon guiding the robotic-arm. The Mako System also allows your surgeon to make adjustments to your plan during surgery as needed.

IMPORTANT INFORMATION

Partial knee replacement

General indications: Partial knee replacement is intended for use in individuals with joint disease resulting from degenerative and post-traumatic arthritis, and for moderate deformity of the knee.

Contraindications: Partial knee replacement surgery is not appropriate for patients with certain types of infections, any mental or neuromuscular disorder which would create an unacceptable risk of prosthesis instability, prosthesis fixation failure or complications in postoperative care, compromised bone stock, skeletal immaturity, severe instability of the knee, or excessive body weight.

Common side effects of knee replacement surgery: As with any surgery, knee replacement surgery has serious risks which include, but are not limited to, peripheral neuropathies (nerve damage), circulatory compromise (including deep vein thrombosis (blood clots in the legs)), genitourinary disorders (including kidney failure), gastrointestinal disorders (including paralytic ileus (loss of intestinal movement)), vascular disorders (including thrombus (blood clots), blood loss, or changes in blood pressure or heart rhythm), bronchopulmonary disorders (including emboli, stroke or pneumonia), heart attack, and death.

Implant related risks which may lead to a revision of the implant include dislocation, loosening, fracture, nerve damage, wear of the implant, metal sensitivity, osteolysis (localized progressive bone loss), and reaction to particle debris. Partial knee implants may not provide the same feel or performance characteristics experienced with a normal healthy joint.

The information presented is for educational purposes only. Speak to your doctor to decide if joint replacement surgery is right for you. Individual results vary and not all patients will receive the same postoperative activity level. The lifetime of a joint replacement is not infinite and varies with each individual. Your doctor will help counsel you about how to best maintain your activities in order to potentially prolong the lifetime of the device. Such strategies include not engaging in high-impact activities, such as running, as well as maintaining a healthy weight. Ask your doctor if robotic-arm assisted surgery is right for you.

Stryker Corporation or its other divisions or other corporate affiliated entities own, use or have applied for the following trademarks or service marks: Mako, Stryker. All other trademarks are trademarks of their respected owners or holders.

References
  1. Bell, Stuart W., Anthony, Iain, Jones, Bryn, MacLean, Angus, Rowe, Philip, and Blyth, Mark. Improved accuracy of component positioning with robotic-assisted unicompartmental knee arthroplasty. The Journal of Bone and Joint Surgery. Volume 98-A: Number 8. April 20, 2016. pp 627-35.

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