Knee Replacement: 62 Questions Patients Ask

The worn cartilage and a thin layer of bone are removed from the ends of the thigh bone (femur) and shin bone (tibia) and replaced with metal implants, with a smooth plastic (polyethylene) bearing between them. The back of the kneecap may also be resurfaced. It reliably relieves arthritis pain and restores function. Learn more about robotic knee replacement.

It is usually time when knee pain limits walking, sleep, work or the activities you enjoy, and non-surgical treatment no longer gives enough relief. X-rays show how much the joint is worn. The decision is yours, made together with Dr. Dold.

The AAOS guideline for knee arthritis strongly supports exercise and physical therapy, anti-inflammatory medication (oral or topical NSAIDs), acetaminophen and education, and supports weight loss, bracing and steroid injections for short-term relief. It recommends against opioid pain medication and against routine hyaluronic acid (gel) injections and arthroscopic “clean-out” surgery for arthritis.¹ See knee arthritis.

There is no strict age limit; the decision depends on your symptoms, X-rays and health. Younger, more active patients have a higher lifetime chance of needing a revision because they live longer with the implant and put more demand on it.² For some younger patients, a knee osteotomy or partial knee replacement may be an option.

Yes. Patients with severe obesity improve as much in function as other patients, but they have higher rates of infection and revision.^3,4 Losing weight before surgery, when possible, lowers these risks.

Yes. Diabetes and smoking both raise the risk of infection.⁴ An HbA1c (blood sugar) level of about 7.7% or higher has been linked to a higher infection risk.⁵ Dr. Dold may ask you to improve these before surgery.

When arthritis is limited to one part of the knee and the ligaments are healthy, a partial knee replacement may be an option. In the TOPKAT randomized trial, partial and total knee replacements gave similar results at 10 years, with similar revision rates.⁶ Dr. Dold performs both robotically and will tell you which suits your knee.

It is possible in selected healthy patients, but replacing both knees at once carries a higher risk of serious complications, including blood clots in the lungs and death, than doing them weeks or months apart.⁷ Most patients are safer having them staged.

Second opinions are always welcome. Dr. Dold can review your X-rays and records. Request an appointment.

Dr. Dold uses the ROSA® Knee System from Zimmer Biomet. Before and during surgery, ROSA® maps your knee, measures its alignment and the tension of the ligaments through a full range of motion, and guides Dr. Dold’s cuts and implant positions to a plan built for your anatomy.

No. Dr. Dold performs the operation. The robot is a precision tool that provides measurements and guidance; it does not operate on its own.

Precision. Studies of the ROSA® system show that bone cuts are accurate to within about 1 mm and 1 degree of the plan, with fewer alignment outliers than conventional instruments.^8,9,10 Across randomized trials, robotic surgery consistently improves the accuracy of implant positioning and alignment.^11,12 It also gives Dr. Dold real-time data on ligament balance, which makes personalized (kinematic) alignment practical.

That is still being studied. Large randomized trials, including the RACER-Knee trial, have found that patient-reported results a year after surgery are similar with robotic and conventional surgery, and a US registry found no difference in early revision rates.^13,11,14 Dr. Dold uses robotics because it brings measurable precision and individualized planning to every knee; your results also depend on the condition of your knee, your rehabilitation and your health.

Your leg will be aligned to a safe, functional position. With restricted kinematic alignment, Dr. Dold aims to restore the alignment your knee naturally had before arthritis, rather than making every knee perfectly straight.¹⁵

The operation itself usually takes about 1 to 2 hours. You will also spend time in pre-op and in recovery.

The incision runs down the front of the knee. Its length depends on your size and your knee; the goal is a safe incision that allows accurate implant placement.

In a healthy knee, the inner (medial) side acts like a stable ball-and-socket while the outer side rolls and glides. The Persona® Medial Congruent bearing is shaped to recreate this: it is deeply dished on the inner side for stability and flatter on the outer side to allow natural motion. In a randomized trial, the medial congruent bearing fixed to the bone as securely as a standard design,²⁰ and in one study 92.6% of patients with this bearing were very satisfied.²¹

Both work well. Dr. Dold usually uses cementless (press-fit) fixation, in which your bone grows into the porous implant surface for a long-lasting biological bond. In younger patients, randomized trials show cementless knees do at least as well as cemented knees.^18,19 Cement may still be used when bone quality is weaker.

Only occasionally. Dr. Dold resurfaces the back of the kneecap when it is needed, rather than routinely. Studies differ: a large UK registry found slightly fewer later revisions when the kneecap was resurfaced, while many surgeons leave a healthy kneecap alone to preserve the patient’s own bone.²² Dr. Dold decides based on the condition of your kneecap at surgery.

Usually, yes. Tell Dr. Dold about any documented metal allergy so the implant options can be reviewed with you before surgery.

A long time. A study in The Lancet found that about 82% of total knee replacements were still working 25 years after surgery.²³ In a large population study, about 90% lasted 20 years.²

It may. Simply tell the security officer that you have a knee replacement; the TSA Notification Card can help.^24,25

Most of Dr. Dold’s patients have spinal anesthesia with sedation, so you are relaxed and comfortable. International consensus recommendations prefer spinal (neuraxial) anesthesia for knee replacement,²⁶ and in a study of more than 270,000 knee replacements, spinal anesthesia was linked to fewer readmissions and shorter stays.²⁷ The final plan is made with your anesthesiologist.

Yes. Many of Dr. Dold’s patients go home the same day; others prefer to stay one night in the hospital. The choice often comes down to your preference, your health and your support at home. Studies of outpatient knee replacement show good results in carefully selected patients, but the evidence is mixed, which is why the decision is individualized.^28,29

Dr. Dold uses several methods together: spinal anesthesia, an adductor canal nerve block, which numbs the knee while keeping the thigh muscles strong enough to walk,³⁰ a long-acting numbing injection placed around the knee during surgery, ice, anti-inflammatory and other non-opioid medications, and a short course of stronger medication if needed.

Usually not. A Cochrane review of 41 randomized trials found that using a tourniquet was linked to more serious adverse events and more pain on the first day, without reducing overall blood loss.³¹

Transfusions are rarely needed. Dr. Dold uses tranexamic acid (TXA), a medication that reduces bleeding and is recommended by the AAOS and other specialty societies.³²

Yes. You receive an antibiotic through your IV before surgery, and doses usually continue for about 24 hours afterward, following guidance from the American Association of Hip and Knee Surgeons.^33,34 Most patients do not need antibiotic pills at home.

Most of Dr. Dold’s patients take aspirin for about 6 weeks after surgery to prevent blood clots. Large randomized trials support aspirin for many patients;^35,36 another large trial found that injected enoxaparin prevented more clots than aspirin after knee replacement, so patients at higher risk may need a stronger blood thinner.³⁷ Dr. Dold will tell you which medication is right for you.

The same day. You walk with a walker and the physical therapy team a few hours after surgery.

Most patients move from a walker to a cane, or to no support, within about 1 to 2 weeks.

Yes. Therapy starts on the day of surgery and continues for several weeks to a few months. Regaining full straightening and bending of the knee in the first weeks is the most important goal.

Most patients regain enough bend for everyday activities like climbing stairs, getting out of a chair and getting in and out of a car. Your final motion depends largely on your motion before surgery and on your therapy in the first weeks.

A small number of patients, about 1 in 20 in one series, need a manipulation under anesthesia, in which the knee is gently bent while you are asleep to break up scar tissue.³⁸ In a randomized trial, manipulation improved knee bend from about 72 to 118 degrees on average.³⁹

Pain and swelling are greatest in the first few weeks and improve steadily over about 3 months. Mild swelling and warmth after activity can last up to a year, which is normal.

Small skin nerves are crossed by the incision. About half of patients notice a patch of numbness next to the scar at one year, but few find it bothersome and it does not affect how the knee works.⁴⁰

Most of Dr. Dold’s patients return to driving at about 2 to 4 weeks, once they are off narcotic pain medication and can control the car safely. Recovery after right knee surgery may take longer. Studies of braking time support a careful return over the first weeks.⁴¹

Patients with desk jobs often return in about 1 to 2 weeks. Jobs that involve standing, kneeling, lifting or labor take longer. In a recent study, 88% of working patients returned to work.⁴²

You will receive specific wound-care instructions. A waterproof dressing usually lets you shower soon after surgery. Avoid soaking the knee in a bath, hot tub or pool until the incision is fully healed and Dr. Dold’s team says it is safe.

Many patients can travel within a few weeks. On long flights, get up and walk regularly, flex your ankles and stay hydrated to lower the risk of blood clots.²⁴

Most patients are walking comfortably and back to most daily activities within about 6 weeks. Strength, stamina and comfort keep improving for several months, and the knee can continue to feel better for up to a year.

Your first follow-up visit is at about 10 to 14 days, followed by visits over the first year and then periodic check-ups with X-rays.

Walking starts on day one. A stationary bike usually follows within the first few weeks, and swimming once the incision has fully healed. Most patients gradually build up to their normal exercise routine over about 3 months.

Most of Dr. Dold’s patients return to golf at about 3 months. In one study, more than half of golfers were back on the course within 6 months, and golf-related pain fell from 83% before surgery to 13% after.⁴³

Yes. Low-impact activities such as walking, cycling, swimming, golf and pickleball are encouraged after knee replacement.⁴⁴ In a large study, more than half of patients returned to sport, typically about 3 months after surgery.⁴⁵

Dr. Dold discusses running case by case, based on your knee, your running experience and your goals. Running is a high-impact activity, and AAOS patient guidance lists jogging among the activities to avoid after knee replacement; low-impact exercise is recommended for most patients.⁴⁴

Yes, most patients can. In one study, 68% of patients could kneel with little or no difficulty, and kneeling becomes more comfortable with practice.⁴⁶ Kneeling does not harm the implant.

Most patients return to walking, golf, cycling, swimming and other low-impact activities. A replaced knee may never feel exactly like a natural knee, and some patients notice clicking, which is normal.

Most patients are satisfied. A widely cited study found that about 1 in 5 patients were not fully satisfied,⁴⁷ but a more recent review found that, on average, about 1 in 10 were dissatisfied.⁴⁸ Realistic expectations are one of the strongest predictors of satisfaction,⁴⁷ which is why Dr. Dold spends time explaining what to expect.

Serious complications are uncommon. Risks include infection, blood clots, stiffness, ongoing pain, instability, fracture around the implant, wear or loosening over time, nerve or blood vessel injury, and anesthesia-related risks. Dr. Dold will review your individual risks at your consultation.

In a study of Medicare patients, infection occurred in about 1.5% within the first 2 years after knee replacement, and was much less common after that.⁴⁹ Smoking, obesity, diabetes and rheumatoid arthritis raise the risk.⁴

Call for fever, increasing redness, warmth or drainage from the incision, calf pain or swelling, sudden severe knee pain, or pain not controlled by your medication. Go to the emergency room for chest pain or shortness of breath.

Most patients never do. A revision may be needed for wear, loosening, infection, instability or a fracture. Modern knee replacements last 20 to 25 years or more in most patients.^23,2

No. For routine dental cleanings and other non-invasive dental care, antibiotics are not needed. Current guidance from the American Academy of Orthopaedic Surgeons (AAOS), the American Association of Hip and Knee Surgeons and the American Dental Association concludes that routine antibiotics before dental procedures do not reduce the risk of infection in a knee or hip replacement.^{50,51,52,53,54}

For most healthy patients, antibiotics are not recommended. The AAOS appropriate use criteria say antibiotics may be appropriate before invasive dental procedures for patients with a weakened immune system, for example from chemotherapy, organ transplantation or certain medications.⁵¹ If that applies to you, Dr. Dold and your dentist will decide together.

There is no fixed rule. Routine cleanings can usually continue as normal. For planned invasive dental work, the timing is decided case by case, and the American Dental Association advises against rigid waiting periods.^50,52 Urgent dental problems should be treated promptly.

Good dental health is part of good overall health, and any dental infection or urgent problem should be treated before surgery. The AAOS guideline found that routine dental screening before joint replacement may not by itself lower the risk of infection.⁵⁰

Knee replacement is covered by most insurance plans when it is medically necessary. Dr. Dold accepts most major insurance plans, including Medicare and Tricare; please call 469-850-0680 to confirm your coverage. See insurance.

Stay as active as you can, work on your thigh-muscle strength and knee motion, control blood sugar and stop smoking. Arrange a ride home and help for the first few days, and set up your home so walkways are clear and things you use often are within easy reach.

Request an appointment online or call 469-850-0680. Walk-in visits are welcome Monday, Wednesday and Friday, 8:30 to 10:30 am. Also see hip replacement questions.