Frequently Asked Questions About Knee Replacement Surgery
Our implants are made out of cobalt chromium molybdenum, a standard metal used in orthopedic implants. The tibial and patellar inserts are made of ultra high molecular weight polyethylene (UHMWPE) or highly crosslinked vitamin-e infused UHMWPE (iTotal only).
Knee arthroplasty procedures using our implants are fully or partially covered by Medicare and most major insurance companies, under the same insurance reimbursement codes as our competitors’ “off-the-shelf” knee implants. Please consult with a surgeon using Conformis technology to learn more about your specific costs and coverage.
Our pre-navigated implants (Identity ImprintTM) have been designed based on advanced CT scan data from about 85,000 real-world Conformis patients. Approximately half of them are women, so female anatomy is taken into account. For the personalized implant option (iTotal® Identity), as we would design your knee just for you, there are no male versus female considerations. It is simply your knee.
The knee joint is comprised of three bones: the femur (thigh bone), the patella (knee cap), and the tibia (shin bone). It can be divided into the medial compartment, the side of your knee that is closest to the center of your body; the lateral compartment, the side of your knee to the outside of your body; and the patellofemoral compartment, which is the area behind the knee cap.
The end of each of the bones of the knee is covered with a layer of smooth, glossy, elastic tissue known as articular cartilage. Cartilage protects the bones while allowing the joint to glide smoothly. It also acts as a shock absorber. Cartilage has no nerve or blood supply. If damaged or injured, it may be difficult for it to heal or repair itself.
Ligaments of the knee link the bones, while muscles and tendons aid in strength, stability, and movement. Ligaments include the anterior cruciate ligment, commonly called the ACL, the posterior cruciate ligament (the PCL), the medial collateral ligament (MCL) and the lateral collateral ligament (LCL). The health and stability of your ligaments can be important determining factors in whether one surgical option is better for you than another.
On the top of the tibia are two crescent-shaped pieces of cartilage calledThese inner and outer pads act as weight distributors when we walk, stand and move about. Their specialized shape also helps to keep the knee stable and conforms to the profile of the femur.
Condyles are rounded prominences at the end of a bone, most often important for articulation with another bone. Each person’s condyles have unique shapes and sizes.
A partial knee replacement preserves the part of the knee not damaged by arthritis and the surgeon treats only the affected compartments of the knee.
In a healthy knee, the ends of the thigh bone, the shin bone, and the knee cap are covered by a layer of articular cartilage. This cartilage acts as a cushion and provides a smooth, gliding surface for the movement of the knee.Through the years, tremendous demands are placed on our knees. In some, the cartilage can begin to fracture or wear away. If the wear becomes significant, the rubbing of exposed bone can result in debilitating pain. This is called osteoarthritis (OA) and it affects millions worldwide.
Osteoarthritis (OA) is considered a progressive disease but the exact causes of are not fully understood. OA is very common in adults over the age of 50, but the condition can affect younger adults as well. People who have a history of past knee injuries, or have placed a lot of stress on their knees from heavy physical activity or weight are also at increased risk.
Symptoms of knee osteoarthritis include:
- Pain during movement
- Stiffness, usually after periods of inactivity
- Lack of flexibility and an inability to move through the full range of motion
- Grating sensation
- Bone spurs – small, hard lumps felt around the joint
There is no known cure for knee osteoarthritis, but there are a number of other treatment options available that you should discuss with your doctor, including:
- Lifestyle changes, such as weight loss, exercise or physical therapy
- Over-the-counter anti-inflammatory pain medication (NSAIDs)
- Corticosteroids (anti-inflammatory knee injections)
- Viscosupplementation (hyaluronic acid knee injections, or lubricating fluid for your joint)
- Joint replacement surgery, or arthroplasty
Prior to Surgery
Talk to your doctor about your options, potential risks, after surgery, and how to plan. Specific information can be found here.
The CT scan is a diagnostic tool for your surgeon to assess the course of treatment for your knee. CT scan data is used to create a 3D model of your knee to either design your personalized knee implant system (in approximately 6 weeks) or to select the best fit size of your pre-navigated implant (in approximately 3 weeks). The advanced scan data also drives the creation of your personalized surgical plan and 3D-printed surgical instruments.
It is recommended to book your CT scan appointment as soon as you can. If you elect to receive a personalized knee implant, then your personalized knee implant cannot be designed until your CT scan images are received. If you elect to receive a pre-navigated knee implant, then the selection of your size, your personalized surgical plan, and your personalized, 3D-printed surgical instruments all rely on the CT scan.
Your surgeon will recommend an imaging center that has been qualified to perform CT scans that capture the required images to design your individualized implant.
The CT scan appointment typically takes 45-60 minutes. It is always a good idea to give yourself more time, and to arrive early to ensure your scan can start on time.
If you choose the personalized implant option, from the time Conformis receives the order and your CT scan it takes 6 weeks to develop and deliver your implant to the medical facility in advance of your surgery date.
If you choose the pre-navigated implant option, then the time to select your optimal implant size, 3D-print your surgical instruments, produce a personalized surgical plan, and deliver everything to the medical facility in a sterile Surgery-In-A-Box kit is approximately 3 weeks.
It can be helpful to designate someone as your primary “caregiver.” This person will be there with you on your day of surgery, help carry your belongings and stay in touch with other family or friends during and immediately following your surgery. The primary caregiver may also be helpful following surgery (i.e., driving home, assisting in follow-up doctor visits, physical therapy and completing light chores around the house).
It may also be helpful to complete as many chores and/or errands as possible prior to surgery. Preparing your home by removing tripping hazards such as rugs and moving your living quarters to the ground floor will ensure an easier rehabilitation.
Prior to your day of surgery, be sure to pack a small suitcase with loose fitting comfortable clothing and necessary toiletries. In some cases you may be in the hospital from 1-3 days. Please check with your surgeon on how long you are expected to stay so you can pack accordingly.
Day of Surgery
Knee surgery has become a very common procedure. A total knee replacement can take 60–90 minutes to complete. Be sure to consult with your surgeon about his/her expectations for the surgery.
After you have been admitted and prior to the actual surgery, you will receive an IV (intravenous) line that is used to administer antibiotics and anesthesia. The actual surgery involves a thin incision on the knee that helps the surgeon gain access to the affected compartment(s). Your surgeon will place your personalized surgical instrumentation on your femur (thigh bone) and tibia (shin bone) in order to facilitate the procedure. Your knee implants are then cemented into place and the incision is closed.
Following surgery, you will focus on recovery and rehabilitation. Performing range of motion exercises during physical therapy is especially important to prevent scar tissue from limiting the flexibility of the new joint. For more information click here.
As every case is different, please be sure to follow your surgeon’s recommendations for pain medication and physical therapy.
You should be able to walk, as tolerated, a few hours after surgery. You may be provided with a knee brace and/or aids such as crutches or a walker to assist you.
Your surgeon will determine whether or not you will need to wear a brace. If you do, you will likely wear your brace for two weeks or less depending upon your surgeon’s recommended weight-bearing protocol.
Following surgery you may not have the full leg control required to work the gas and brake pedals. As a safety precaution, your surgeon may recommend that you not drive for a few days.
Your return to work will be dependent on your job requirements and endurance. Typically, patients return to office work in two to three weeks; jobs that require longer periods of standing may require a longer knee replacement recovery time.
Your surgeon may prescribe medication to control pain after surgery and/or coated aspirin to prevent blood clots. It is important that you consult with your physician before taking any non-prescribed medications.
Following surgery, it is important to keep your incision covered with a clean dressing. Your surgeon will recommend that you use caution while bathing to keep your incision dry. Waterproof bandages are recommended. Be sure to contact your surgeon if you notice any changes in the incision such as swelling or drainage during the recovery period.
Immediately after your procedure, you may have a low grade fever (up to 38 °C). It is important to contact your doctor if your temperature elevates above 38 °C degrees or lasts longer than one week.
Your surgeon can best determine how much physical therapy is appropriate for you. In many cases, physical therapy is prescribed to avoid the build-up of scar tissue, help restore normal movement in your joint, build up strength in the joint and surrounding muscles, ease pain and swelling, and help with circulation. In all cases, an immediate postoperative recovery will focus on protecting the knee, minimizing discomfort, and ensuring an early return to motion. After that, your surgeon will prescribe a set of simple exercises to aid in knee replacement surgery recovery and strengthen your knee.
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Watch these knee replacement video testimonials from real Conformis patients to learn more about their surgery and recovery experiences.View Patient Stories