What are the considerations for total knee replacement (TKR) in young patients?

Total Knee Replacement in Young Patients

TKR can be performed in young patients (≤55-60 years) with advanced osteoarthritis when conservative treatments have failed, but they should be counseled about realistic expectations, higher revision rates, and the likelihood of needing future revision surgery given their longer life expectancy. 1, 2

Patient Selection Criteria

Young patients must meet specific criteria before proceeding to TKR:

• Radiographic evidence: Moderate-to-severe osteoarthritis (Kellgren-Lawrence grade 3-4) with documented joint damage 1
• Failed conservative management: Must have completed ≥1 trial of appropriate nonoperative therapy including physical therapy, NSAIDs, and/or intraarticular injections without improvement 1
• Symptom severity: Moderate-to-severe pain or significant functional limitation that diminishes quality of life 1, 3
• Shared decision-making: The indication for TKR must be established through a collaborative process with the surgeon 1

Alternative Treatments to Exhaust First

Before considering TKR in young patients, the following should be attempted:

• Joint-sparing procedures: High tibial osteotomy for correction of lower-limb deformities in appropriate candidates 2
• Unicompartmental knee arthroplasty: For isolated single-compartment disease (usually medial), which offers shorter hospital stays and faster recovery compared to TKR 3
• Conservative measures: Extended trials of physical therapy, weight loss, activity modification, and pharmacologic management 1, 2

Expected Outcomes and Survival Rates

The evidence shows encouraging but imperfect results in young patients:

• Survival rates: 89.7% at 13 years 4, 94% at 18 years for femoral/tibial components 5, and >90% in the first 7 years 6
• Functional outcomes: 89% achieve good or excellent outcomes for pain and function up to 5 years 7, with mean Hospital for Special Surgery scores improving from 55 to 92 points 5
• Activity levels: 24% of young patients return to high-activity sports (tennis, skiing, bicycling) with Tegner-Lysholm scores improving from 1.3 to 3.5 points 5

Revision Risk and Complications

Young patients face substantially higher revision rates than older populations:

• Overall revision rate: 8.8% in registry data at mean 5.4-year follow-up 6, which is higher than the general TKR population
• Primary causes of revision: Aseptic loosening (38% of revisions) and infection (33% of revisions) are the dominant failure mechanisms in young patients 6
• Timing considerations: The 2023 ACR/AAHKS guideline conditionally recommends proceeding without arbitrary 3-month delays once criteria are met, as patients have already attempted prolonged conservative treatment 1

Critical Counseling Points

The strongest predictor of satisfaction is realistic patient expectations 2. Young patients must understand:

• Higher physical demands: Younger patients are more active and demanding, leading to increased mechanical stress on the prosthesis 4, 2
• Likelihood of future revision: Given survival rates of 87-94% at 15-18 years, most patients under 55 will require at least one revision surgery in their lifetime 5
• Functional limitations: While outcomes are good, young patients report lower satisfaction compared to elderly patients, likely due to higher expectations 2
• Polyethylene wear: Although not a major problem in the first 8 years with modern posterior-stabilized designs, long-term wear remains a theoretical concern 5

Technical Considerations

• Prosthesis selection: Posterior-stabilized, posterior cruciate-substituting designs with cemented fixation show durable results in young patients 4, 5
• Preoperative imaging: Standing AP and lateral radiographs plus full-length hip-to-ankle views for alignment assessment are essential 8
• Postoperative management: Early mobilization and supervised exercise programs during the first 2 months improve physical function 8

Common Pitfalls to Avoid

• Operating too early: Performing TKR before exhausting conservative and joint-sparing options increases lifetime revision burden 2
• Unrealistic expectations: Failing to counsel patients about activity limitations and revision likelihood leads to dissatisfaction 2
• Ignoring comorbidities: Patients should be educated about increased surgical complications associated with obesity, poor glycemic control, and nicotine use, though lack of resources to modify these should not be an absolute contraindication 1