Orthopedics Hip & Knee Knee Replacement Surgery Knee Replacement Surgery: Overview By Jonathan Cluett, MD twitter linkedin Jonathan Cluett, MD, is a board-certified orthopedic surgeon with subspecialty training in sports medicine and arthroscopic surgery. Learn about our editorial process Jonathan Cluett, MD Medically reviewed by Medically reviewed by Stuart Hershman, MD on January 19, 2021 linkedin Stuart Hershman, MD, is a board-certified spine surgeon. He specializes in spinal deformity and complex spinal reconstruction. Learn about our Medical Review Board Stuart Hershman, MD on January 19, 2021 Print Table of Contents View All Purpose How to Prepare What to Expect Recovery Long-Term Care Knee replacement surgery (knee arthroplasty) involves removing a patient's damaged joint surface and replacing it with a metal and plastic implant. This surgery is performed on patients with severe knee arthritis (most commonly, osteoarthritis) to decrease pain and improve mobility, and it tends to have a high success rate. While knee replacement surgery is considered a safe and effective operation, it's important to gain knowledge about the potential risks involved, as well as the recovery process, which may take up to a year in some patients. sittithat tangwitthayaphum / Getty Images What Is Knee Replacement Surgery? During a total knee replacement (TKR), the bone and cartilage at the end of the thigh bone and shinbone are removed. An implant is then placed on the knee to create a new joint surface. This implant functions similarly to a normal knee. Those who have disease limited to one area of their knee (for example, only the medial or inside compartment of their knee) may be candidates for partial knee replacement instead of TKR. However, most patients require the latter, which is focused on here. Total knee replacement surgery takes one to two hours and is performed by an orthopedic surgeon in a hospital. Less often, it is performed in an outpatient surgical center. Your surgical team will help you decide what type of anesthesia is best for you: General anesthesiaRegional anesthesia (e.g., epidural, spinal, or femoral block) What Is a Custom Knee Replacement? Various Surgical Techniques There are two main surgical techniques used in total knee replacement surgery: the traditional technique and the minimally invasive technique. The traditional technique involves making an 8- to 12-inch incision in the knee to expose the joint. Once this is done, damaged tissues are removed and the knee implant is placed. The minimally invasive technique involves making a smaller incision (3 to 5 inches) and using long, thin surgical instruments to remove the tissue and position the implant. Over the years, the minimally invasive technique has evolved to include three main approaches: The subvastus approach: This approach preserves the quadriceps tendon and most of the blood vessels supplying the knee.The midvastus approach: This approach preserves the quadriceps tendon and may be associated with less blood loss and a shorter operation time when compared with the subvastus approach.The quadriceps-sparing approach: This approach preserves both the quadriceps muscles and tendon. Minimally invasive approaches are associated with less blood loss, reduced postoperative pain, and a shorter hospital stay. Additionally, because there is less tissue trauma during surgery, patients may be able to reach milestones—like walking with a cane—sooner than with traditional surgery. Computer-Assisted Total Knee Replacement Some surgeons utilize a sophisticated computer imaging system when performing total knee replacements. While this surgical approach involves a longer operation time and is more costly, it may allow for a more precise implant alignment. Talk with your surgeon if you are interested in this investigational technology. Implant Types A knee implant is usually made of metal (e.g., cobalt chrome or titanium) and plastic (polyethylene). Each prosthesis typically replaces up to three bone surfaces: The top surface of the tibiaThe lower end of the femurThe back surface of the kneecap (patella) There are a variety of knee joint implants out there. Your implant will be selected during a pre-operative visit with your surgeon. The specific implant used for your knee replacement will depend on various factors, such as: Age, weight, and activity levelSurgeon's preference and prior experience with the implantAmount of arthritis-related bone loss that has occurredIntegrity of the ligaments supporting the knee Do not hesitate to ask your surgeon questions about why a particular implant is being recommended for you. There are also different ways in which the implant is placed during the surgery. Traditionally, the implant is fixed into the bone with cement. Now, though, a novel cement-less technique may be used. This means that the implant is press-fit onto the bone, allowing the bone to grow and permanently bond to the implant without any adhesive. There is still debate within the medical community about whether a cemented or cement-less fixation is better. Early research has found that in young patients, cement-less fixation may provide better outcomes in terms of pain relief and restoring knee function. Contraindications Absolute contraindications to undergoing knee replacement surgery include: An infected knee joint (current or within the last year)A current infection elsewhere in the bodyKnee extensor mechanism problems, such as a patella (kneecap) fracture or patella tendon tearUnstable medical condition Relative contraindications include: Insufficient bone stock for prosthesis implantationA skin condition over the knee jointMorbid obesityNeuropathic arthropathy (called a Charcot knee)Severe peripheral vascular diseaseCertain psychiatric illnesses, especially a history of substance abuseUnrealistic expectations with regard to the potential surgical outcome Potential Risks Knee replacement surgery has become quite common. Fortunately, well over 90% of patients who undergo knee replacement surgery have good results, but there are still risks that must be considered. Besides general surgical risks like blood clots, pneumonia, and bleeding, other potential complications that may occur after a knee replacement surgery include: Surgical site infectionWound dehiscenceContinued stiffness Peripheral nerve injuryKnee fracture The Seriousness of Infections After Knee Replacement Purpose of Knee Replacement Surgery The joint inflammation that characterizes arthritis can lead to cartilage loss and exposed bone over time. With the normal, smooth joint surface compromised, pain and disability can occur. The purpose of knee replacement surgery is to restore knee function, alleviate symptoms like knee pain and stiffness, and improve mobility and overall quality of life. Knee replacement surgery is indicated for patients who: Have failed to get better after six months of nonsurgical therapies (e.g., weight loss, aerobic exercise, taking a nonsteroidal anti-inflammatory drug, and undergoing corticosteroid knee joint injections).Have evidence of end-stage knee arthritis on X-raysHave severe knee pain, especially at nightHave decreased mobility and difficulty performing activities of daily living (e.g., bathing and dressing) While the vast majority of knee replacement surgeries are performed in older individuals with osteoarthritis, surgery may also be performed in people with one or more damaged knee joints from post-traumatic arthritis, or in people with inflammatory arthritis like rheumatoid arthritis or psoriatic arthritis. Rarely, children with juvenile idiopathic arthritis may undergo knee replacement surgery. Why Is a Knee Replacement Surgery Performed? How to Prepare After scheduling your knee replacement surgery, you will be provided with instructions on how to prepare for the operation. In addition to standard directions all surgical patients are given—like stopping certain medications for a period of time, stopping smoking for at least two weeks prior to surgery, and avoiding food after midnight on the eve of your surgery—your doctor may suggest: Meeting with your primary care physician to optimize underlying health conditions (e.g., diabetes) and undergo preoperative studies, like an electrocardiogram (ECG) and blood testsAttending a preoperative education classPacking rubber-soled, flat shoes to leave the hospital inRenting/purchasing a walker, which a loved one should bring to the hospital before you are dischargedLining up help at home for a week or two after being discharged from the hospital You will also want to prepare your home for recovery after surgery. Start by removing fall hazards like throw rugs and loose electrical cords. Since stairs can be challenging to manage after surgery, setting up a temporary bedroom on your first floor is also a reasonable idea. Prevent Falls at Home With These Changes What to Expect on the Day of Surgery On the day of surgery, you will first go to a pre-operative room where you will change into a hospital gown. A nurse will then record your vital signs and place a peripheral IV in your hand or arm. After briefly meeting with members of the surgical and anesthesia teams, you will be taken into the operating room. If undergoing general anesthesia, you will be given medications to put you to sleep and an endotracheal tube connected to a breathing machine (ventilator) will be placed. If you are undergoing regional anesthesia, you will be given a sedative to relax you while the anesthesiologist performs a nerve block (usually in your lower back). Knee replacement surgery will then typically proceed with the following steps: The surgeon will first clean the area around the knee with an antiseptic solution.The surgeon will make an incision on your knee (larger if using the traditional technique, smaller if opting for a minimally invasive one).The damaged parts of your knee joint will be removed. If the minimally invasive technique is used, the surgeon will use special surgical instruments to minimize tissue disturbance.Next, the surgeon will attach a prosthesis to the bone, most commonly with cement.Once the prosthesis is placed, the incision site will be closed with staples or stitches. A drain may be placed at the surgical site, which will be removed later.A sterile bandage will then be placed over the knee wound. Knee Replacement Surgery: Step by Step Recovery You can expect to stay in the hospital for approximately one to four days after your operation. While many patients experience significant pain relief and a rapid improvement in knee functioning within weeks of the surgery, full recovery can take anywhere from six months to a year. As you recover in the hospital, you can expect the following: You will begin knee exercises and work with a physical therapist.You may use a continuous passive motion (CPM) machine for your knee (based on surgeon preference).You will take a blood thinner (an anticoagulant) to prevent blood clots. Once discharged home, it's important to follow your surgeon's post-operative instructions, which may include: Wearing a compression sockElevating/icing your knee to reduce swellingTaking medication as directedResuming your normal diet and maintaining a normal weightKeeping your wound clean and dry and changing the knee bandage as instructed.Resuming normal activities within three to six weeks after surgery. Long-Term Care The success of knee replacement surgery depends partially on the rehabilitation period that follows the operation. With rehabilitation, you can generally expect the following after surgery: You should be able to almost fully straighten out the replaced knee.You should be able to climb stairs and bend the knee enough to get in and out of a car.You may still experience some knee discomfort and stiffness after surgery, especially when bending the knee excessively.You may hear a clicking sound when walking or bending (this usually decreases over time). Besides attending physical therapy appointments and engaging in various exercises at home, it's important to follow-up with your surgeon as advised. Your surgeon will want to ensure that your knee is maintaining good strength, stability, and mobility. Will I Ever Need Revision Surgery? Even though over 80% of knee implants last 25 years or longer, revision surgery may be indicated for various complications—the main one being loosening or wearing out of your knee implant. Younger patients are more likely to experience implant loosening because they live longer and tend to be more active. Knee Replacement Surgery: Long-Term Care A Word From Verywell No doubt, many people have knee arthritis, but it can be difficult to know when the right time is to have knee replacement surgery. To make the best decision, be sure to meet with and engage in thoughtful discussions with your primary care physician, rheumatologist, and/or orthopedic surgeon. Do not hesitate to ask questions, voice your concerns, and seek out second opinions. Reasons to Delay or Decline Knee Replacment Was this page helpful? Thanks for your feedback! Dealing with joint pain can cause major disruptions to your day. Sign up and learn how to better take care of your body. Click below and just hit send! Sign Up You're in! Thank you, {{form.email}}, for signing up. There was an error. Please try again. What are your concerns? Other Inaccurate Hard to Understand Submit Article Sources Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. Cleveland Clinic. Knee Replacement. Reviewed July 2016. Foran J. Unicompartmental Knee Replacement. American Academy of Orthopedic Surgeons. Reviewed April 2016. Edwards PK, Milles JL, Stambough JB, Barnes CL, Mears SC. Inpatient versus Outpatient Total Knee Arthroplasty. J Knee Surg. 2019 Aug;32(8):730-735. doi:10.1055/s-0039-1683935 Tzatzairis T, Fiska A, Ververidis A, Tilkeridis K, Kazakos K, Drosos GI. Minimally invasive versus conventional approaches in total knee replacement/arthroplasty: A review of the literature. 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