Can both knees be replaced at the same time?

Replacing both knees during the same anesthetic is called simultaneous bilateral total knee arthroplasty. Replacing one knee and returning for the other later is staged bilateral replacement. A simultaneous operation can mean one hospitalization, one anesthetic, and one overall recovery period. It also means two surgical sites, greater blood loss potential, more difficult early mobility, and no comfortable “good leg” to rely on.

Staged surgery separates those demands. The first knee can recover strength and motion before the second operation, and the medical stress is divided between two episodes. The tradeoff is a second anesthetic, a second rehabilitation period, and more total calendar time before both knees are treated. Neither strategy is universally best.

The simultaneous option is attractive when both knees have severe, similarly limiting arthritis. Treating only one knee may leave the other too painful or unstable to support rehabilitation. A patient may also want to reduce travel, time away from work, or the number of separate perioperative episodes.

Those practical advantages matter, especially for Neighbor Island families. They do not erase medical risk. AAHKS reported research comparing more than 8,200 bilateral and unilateral knee replacements in which bilateral surgery had higher complication risk even among healthier patients, although mortality did not differ in that analysis. This is why convenience must be weighed against the size of the physiologic event.

For a carefully selected patient, a one-stage approach may offer several practical benefits:

Staging is often favored because the immediate burden of each operation is smaller. One leg can assist transfers, stairs, and gait while the operated knee recovers. The team can also learn from the first recovery—such as nausea, medication sensitivity, swelling, stiffness, or home-support needs—before planning the second.

Selection is stricter than for a routine single-knee replacement. A potential candidate generally needs severe symptomatic arthritis in both knees, good cardiopulmonary reserve, manageable medical risk, adequate baseline strength, and a realistic plan for help after discharge. Age alone does not decide the answer, but overall physiologic reserve matters.

Conditions that can increase surgical risk—such as poorly controlled heart or lung disease, significant anemia, kidney disease, uncontrolled diabetes, prior blood clots, active infection, frailty, or limited mobility—may push the recommendation toward staged surgery or further optimization. The final decision also depends on anesthesia review, hospital resources, blood-management protocols, and the surgeon’s judgment.

After a unilateral replacement, the other leg usually helps with standing, transfers, and stairs. After simultaneous bilateral surgery, both knees are swollen and healing. Early therapy therefore requires more upper-body effort, more planning, and reliable assistance. A walker is usually essential at first, and some patients may need a higher level of rehabilitation support than they would after one knee.

Review the ordinary knee replacement recovery milestones, then discuss how they change when both legs are postoperative. The goal is not merely to leave the hospital; it is to recover safely without falls, missed medication, dehydration, uncontrolled pain, or an exhausted caregiver.

Every knee replacement carries risks including bleeding, transfusion, blood clots, infection, stiffness, wound problems, cardiopulmonary complications, and readmission. Operating on both knees at once increases the amount of surgery performed during a single physiologic event. Modern blood conservation, tranexamic acid, multimodal pain control, early mobilization, and clot-prevention protocols help, but they do not make risk identical for every patient.

A 2024 national claims study of 14,870 simultaneous bilateral procedures found that robotic or computer assistance did not reduce 30-day mortality, respiratory failure, or fat embolism compared with conventional instrumentation. Technology may help execute a plan, but it is not a substitute for patient selection, medical optimization, anesthesia planning, and an experienced rehabilitation pathway.

There is no single interval that fits everyone. The second operation is usually considered when the first knee has healed adequately, motion and strength are progressing, walking is safe, the wound is healthy, medical issues are controlled, and the patient is ready to repeat the process. Work, caregiving, travel, and insurance timing may also matter.

A 2026 study of 4,210 patients undergoing staged bilateral replacements found that the interval was associated with patient-reported recovery, with shorter intervals showing favorable improvement in selected measures. The authors still concluded that timing should be individualized to goals and recovery trajectory. An observational result does not mean everyone should rush into the second operation; the first knee and the whole patient need to be ready.

When staging, the more painful knee is often treated first—but pain is not the only consideration. The surgeon also examines deformity, stiffness, instability, bone loss, motion, and which leg can safely support rehabilitation. Occasionally the mechanically worse knee should be addressed first even when symptoms are close.

Standing X-rays of both legs and a focused examination help identify whether one knee is driving gait compensation or whether hip, spine, neurologic, or balance problems may affect recovery. The plan should account for the second knee from the beginning rather than treating it as an afterthought.

Strengthening cannot reverse advanced cartilage loss, but it can improve the starting point for surgery. A focused prehabilitation program can address quadriceps strength, hip strength, balance, walker technique, transfers, stairs, and endurance. Upper-body conditioning may also make early walker use easier.

Preparation should include nutrition, anemia evaluation, medication planning, diabetes and blood-pressure control, smoking cessation, sleep-apnea management, and a realistic home setup. AAOS emphasizes optimization and shared decision-making because factors such as glucose control, severe obesity, and preoperative opioid use can affect complications or recovery.

A healthy patient can still struggle without reliable support. Before considering two knees at once, identify who will help with meals, medications, transportation, pets, bathing, compression devices, exercises, and urgent concerns. Measure doorway access, bathroom safety, bed height, and the number of unavoidable stairs.

Caregiver availability should be specific—not simply “family will help.” Decide who is present during the first nights, who can assist without being injured, and what happens if that person becomes unavailable. A staged plan may be safer when home support is thin, even if the medical evaluation is favorable.

One combined operation can appear to simplify flights, lodging, and time away from home. However, the early recovery burden and the possibility of needing additional rehabilitation may make travel more complicated, not less. The best plan accounts for where surgery occurs, how long you should remain nearby, who accompanies you, where therapy happens, and how urgent concerns will be evaluated after you return home.

Bring standing X-rays of both knees, a medical history, medication list, prior treatment records, and your anticipated caregiver and travel plan. The visit can then compare the total logistics of simultaneous and staged care rather than focusing only on the number of trips.

A useful consultation should address the whole pathway:

Both knees can be replaced during one operation in selected patients, but fewer appointments do not automatically mean an easier or safer recovery. Simultaneous surgery concentrates the medical and rehabilitation burden; staged surgery spreads it across two events and allows the first knee to become a support leg.

Dr. Paul Morton evaluates both knees, medical risk, strength, home support, travel logistics, and recovery goals before recommending a simultaneous or staged approach. To compare the options using your current standing X-rays, schedule a knee replacement consultation or call (808) 439-6201.

• AAHKS: Study Examines Safety of Bilateral Total Knee Arthroplasty
• HSS Journal: Simultaneous bilateral total knee arthroplasty with technology assistance versus conventional instrumentation
• Journal of Arthroplasty: Timing between staged bilateral total knee arthroplasties
• AAOS: Surgical Management of Osteoarthritis of the Knee guideline update