Total Knee Replacement

Educational overview. Not medical advice.

Total knee replacement removes damaged cartilage and a small amount of bone from the knee and replaces the joint surfaces with metal and durable plastic to reduce pain and improve function.

Indications

Main reasons this surgery is recommended:

  • Advanced knee arthritis (osteoarthritis or inflammatory arthritis) with persistent pain and disability despite appropriate non-surgical treatment.6,7
  • Severe pain with walking, stairs, standing, or sleep.
  • Marked stiffness or deformity (bow-legged or knock-kneed) that limits daily activities.
  • Substantial loss of function and quality of life (difficulty dressing, bathing, shopping, working).

Common reasons to delay or avoid surgery:

  • Absolute: active infection (skin, dental, urinary, or systemic).
  • Relative: poorly controlled diabetes, active nicotine use, severe anemia/malnutrition, uncontrolled cardiopulmonary disease, or inability to participate in rehabilitation.7

Benefits and alternatives

Benefits:

  • Major pain reduction and improved walking tolerance.
  • Improved ability to climb stairs, stand, and perform daily tasks.
  • Improved alignment and stability in many patients.
  • Improved sleep and quality of life.

Alternatives:

  • Activity modification; cane/walker; weight management.
  • Physical therapy: strengthening (quadriceps/hip), flexibility, gait training.
  • Medications: acetaminophen; NSAIDs if safe; topical NSAIDs.
  • Injections (corticosteroid or viscosupplementation in selected patients) for temporary relief.
  • Bracing (unloader brace for unicompartment disease in selected patients).
  • Other surgery in select cases: unicompartmental knee arthroplasty, osteotomy, or arthroscopic debridement (limited role).

Surgical procedure

  • Incision over the knee; the surgeon protects nerves and blood vessels.
  • Removal of damaged cartilage and a small amount of bone from the femur and tibia.
  • Placement of metal femoral and tibial components.
  • Placement of a polyethylene (plastic) insert that acts as the new bearing surface.
  • Patellar resurfacing (plastic button) may be performed depending on patient factors and surgeon preference.
  • The knee is balanced for stability, alignment, and range of motion, then the incision is closed.

Key variants: implant design (cruciate-retaining vs posterior-stabilized vs constrained), fixation (cemented vs cementless), and use of robotic or navigation assistance (surgeon- and patient-specific).

Implant specifics and MRI considerations

  • Typical materials: cobalt-chromium or titanium alloys with a polyethylene insert; patellar component is usually polyethylene.
  • Fixation may be cemented or cementless; choice depends on bone quality and surgeon preference.
  • Implants are intended to stay in permanently; removal is usually only for complications (infection, loosening, instability, fracture).
  • Most contemporary implants are MRI-conditional; MRI is usually possible but can cause artifact near the knee. Inform radiology and keep implant details if available.

Typical anesthesia

  • Common options: spinal anesthesia with sedation or general anesthesia.
  • Multimodal pain control is typical, often including periarticular local anesthetic injection and/or an adductor canal nerve block to reduce early pain and opioid use.8
  • Many patients go home the same day or after 1 night, depending on medical risk, mobility, and pain control.

Recovery timeline

(Your surgeon’s protocol may differ based on implant type, soft-tissue balance, and medical risk.)

Time point Pain and swelling (expected trajectory) Immobilization/weight-bearing Activity and restrictions Physical therapy
Days 0-3
- Moderate pain first 24-72 hrs
- Swelling/bruising common
 - Usually weight bearing as tolerated with walker
- Short, frequent walks
- Avoid twisting/pivoting
- Start day 0-1
- Gait training, ankle pumps, basic ROM
14 days
- Pain improving; taper opioids common
- Swelling persists
 - Transition walker -> cane as safe
- Wound check; staples/sutures often removed
- No high-impact
- ROM goals set; strengthen quads/hip
- Emphasize extension
4 weeks - Mild to moderate soreness with activity - Often cane for longer distances
- Increase walking; avoid kneeling if painful
- Avoid running/jumping
- Progressive ROM and strengthening
- Stairs practice
8 weeks - Intermittent aches; endurance improving - Usually independent walking
- Many return to driving if criteria met
- Light work often possible
 - Strength, balance, gait normalization
12 weeks - Pain typically low; stiffness may persist - Full weight bearing - Gradual return to low-impact exercise - Higher-level strengthening; functional training
6 months - Continued gains; some swelling with long days - No brace - Most low-impact activities allowed - Independent maintenance program

Risks and complications

Common:

  • Pain, swelling, bruising; numbness near the incision; temporary limp; sleep disturbance.
  • Stiffness (may require intensified therapy; rarely manipulation under anesthesia).
  • Anemia or fatigue during early recovery.

Less common:

  • Infection (often reported around 0.5% to 1.5% in the first year; risk varies by health status and surveillance methods).3,4
  • Blood clots (DVT/PE); risk reduced with early walking and prescribed prophylaxis.5
  • Instability, delayed wound healing, persistent pain.

Rare but serious:

  • Periprosthetic fracture, implant loosening/failure, major nerve injury, deep infection requiring additional surgery.

Patient-specific risk modifiers:

  • Higher risk with active nicotine use, poorly controlled diabetes, obesity, immunosuppression, poor nutrition, prior knee surgery, and limited mobility.7

Durability and revision risk

  • Expected longevity is commonly 15-25+ years, depending on age, activity level, weight, alignment, and implant factors.
  • Long-term data suggest about 82% of total knee replacements last 25 years (not revised); outcomes vary by population and era.1
  • Registry analyses report many modern total knee implant options with revision rates under 3% at 10 years and under 5% at 15 years (implant- and patient-dependent).2
  • Common reasons for revision: loosening/wear, infection, instability, stiffness, and periprosthetic fracture.
  • Younger, high-demand patients generally have higher lifetime revision risk due to longer time living with the implant.1

Practical instructions

  • Pain control: use a multimodal plan (scheduled acetaminophen; NSAID if allowed; ice; limited opioid only as needed). Avoid alcohol/sedatives with opioids; do not drive on opioids.
  • Constipation prevention if using opioids: hydration, fiber, stool softener, and an osmotic laxative if needed.
  • Wound care: keep dressing clean/dry; follow surgeon instructions for showering; avoid soaking (bath/pool/ocean) until cleared.
  • Swelling management: frequent walking, ankle pumps, leg elevation, and icing as instructed.
  • Blood clot prevention: take prescribed prophylaxis exactly as directed and walk frequently; use compression if recommended.5
  • Range of motion: prioritize full knee extension early; flexion improves over weeks to months.
  • Driving: only when off opioids, alert, and able to brake quickly and safely; commonly 2-6 weeks (often longer for right knee).
  • Return to work (typical ranges): desk work 2-4 weeks; standing/light duty 6-12 weeks; heavy labor often 3-6+ months (individualized).
  • Travel/flying: discuss timing with your surgeon; for long trips, stand/walk regularly, hydrate, and do ankle pumps; follow your prescribed VTE plan.5
  • Red flags (urgent): fever with worsening knee pain, increasing redness or drainage, calf swelling/pain, chest pain or shortness of breath, sudden inability to bear weight, new/worsening foot numbness or weakness.

FAQ

  1. How much pain is normal? Pain is usually highest in the first 2-3 days, then steadily improves; therapy can cause temporary soreness.
  2. When can I shower? Depends on dressing and closure; follow surgeon instructions and avoid soaking until cleared.
  3. Is swelling normal? Yes. Swelling can last weeks to months; walking and elevation help.
  4. When can I drive? When off opioids and you can safely control the vehicle and brake quickly; often 2-6 weeks.
  5. Will metal detectors go off? Sometimes. Policies vary; an implant card may help but is not always required.
  6. Can I get an MRI? Usually yes (MRI-conditional implants), but the area around the knee may have imaging artifact.
  7. Do I need PT? Most patients benefit; consistent home exercises and supervised therapy improve motion and function.
  8. What signs suggest infection or a clot? Worsening drainage/redness/fever, calf swelling/pain, chest pain, or shortness of breath require urgent evaluation.

Disclaimer: This handout is educational and not individualized medical advice. Follow your surgeon and physical therapist instructions, which may differ based on your implant, anatomy, and medical risk.

Bibliography

  1. Evans JT, Walker RW, Evans JP, Blom AW, Sayers A, Whitehouse MR. How long does a knee replacement last? A systematic review and meta-analysis of case series and national registry reports with more than 15 years of follow-up. Lancet. 2019;393(10172):655-663.
  2. National Joint Registry for England, Wales, Northern Ireland and the Isle of Man. 22nd Annual Report 2025. Surgical data to 31 December 2024. Hemel Hempstead (UK): NJR; 2025.
  3. Weinstein EJ, Klement MR, Greenky MR, et al. Incidence of prosthetic joint infection after total hip arthroplasty and total knee arthroplasty. JAMA Netw Open. 2023;6(10):e2336905.
  4. Ma T, Liu Y, Li S, et al. Incidence of periprosthetic joint infection after primary total knee arthroplasty: meta-analysis and bibliometric study. 2024.
  5. Parvizi J, Gehrke T, Chen AF, et al. Recommendations from the ICM-VTE: Hip and Knee. J Bone Joint Surg Am. 2022;104(Suppl 1):5-7.
  6. American Academy of Orthopaedic Surgeons. Surgical Management of Osteoarthritis of the Knee: Evidence-Based Clinical Practice Guideline. Rosemont (IL): AAOS; 2022.
  7. Hannon CP, Goodman SM, Austin MS, et al. 2023 American College of Rheumatology and American Association of Hip and Knee Surgeons clinical practice guideline for the optimal timing of elective hip or knee arthroplasty. Arthritis Care Res (Hoboken). 2023;75(11):2227-2238.
  8. Kopp SL, et al. Regional Nerve Blocks in Primary Total Knee Arthroplasty: AAHKS Clinical Practice Guideline. Rosemont (IL): AAHKS; 2022.
  9. American Academy of Orthopaedic Surgeons. Total Knee Replacement. OrthoInfo. Updated periodically.
  10. American Joint Replacement Registry. AJRR 2024 Annual Report. Rosemont (IL): AAOS; 2024.