Total Knee and Hip Replacement: Am I a Candidate and What Should I Expect?

Research-informed explainer — last updated April 12, 2026

Total knee and hip replacement are among the most commonly performed and reliably successful elective surgeries in medicine — but the single strongest predictor of whether you will be satisfied is whether your pre-operative expectations matched what surgery can actually deliver. Understanding candidacy criteria, realistic outcomes, and the factors that affect your individual result will help you have that conversation with your surgeon.

This article draws on research from five orthopaedic surgeons with expertise in joint arthroplasty. Neil Sheth, MD, Chief of Orthopaedic Surgery at Pennsylvania Hospital and Vice Chair at Penn Medicine, published the 2018 volume projection study (cited over 2,000 times) showing total joint arthroplasty demand will reach 1.26 million procedures annually in the U.S. by 2030. Kenneth Mathis, M.D., Professor at UTHealth Houston's McGovern Medical School, won the prestigious John Insall Award for his study demonstrating that patient expectations are the single strongest predictor of TKA satisfaction. Giles Scuderi, M.D., Adult Knee Reconstruction Fellowship Director at Lenox Hill Hospital in New York, published the New Knee Society Scoring System, long-term survivorship data on cemented TKA, and follow-up data in young active patients. Joshua Rozell, MD, at NYU Langone, published 2023 Medicare projections for primary hip and knee arthroplasty through 2060. Robert Pivec, M.D., at HonorHealth Scottsdale, published on the effects of opioid use and obesity on arthroplasty outcomes.

How common is total joint arthroplasty, and why is demand growing?

Neil Sheth's 2018 projection study estimated that by 2030, over 1.26 million total joint arthroplasties will be performed annually in the United States — a 143% increase from 2012. Joshua Rozell's 2023 Medicare update projected this growth will continue through 2040-2060 as the population ages and younger patients increasingly qualify.

The main driver is osteoarthritis — the progressive wearing away of joint cartilage that causes pain, stiffness, and functional limitation. For the knee, approximately 90% of total knee arthroplasties (TKA) are performed for OA. For the hip, OA accounts for roughly 80%, with hip dysplasia, osteonecrosis, and post-traumatic arthritis making up much of the remainder.

Who is a candidate for total knee replacement?

There is no single threshold that triggers TKA. The American Academy of Orthopaedic Surgeons recommends TKA when:

• Moderate to severe knee pain that significantly limits daily activities (walking, stairs, rising from a chair)
• Symptoms are not adequately controlled by non-surgical treatment (NSAIDs, physical therapy, weight loss, injections)
• Radiographic evidence of advanced osteoarthritis (Kellgren-Lawrence grade 3 or 4 — significant joint space narrowing, osteophytes, subchondral sclerosis)
• Clinically, significant deformity (varus/valgus alignment) contributing to mechanical symptoms

Age is not a strict criterion — TKA has been performed successfully in patients ranging from their 30s to their 90s, though survivorship and activity considerations differ by age group. Giles Scuderi's long-term follow-up study of TKA in young active patients aged 55 and under showed good 22-year survivorship, but revision rates were higher than in older patients — reinforcing that surgery should not be rushed in younger patients who still have viable non-surgical options.

Who is a candidate for total hip replacement?

For total hip arthroplasty (THA), the Lancet hip arthroplasty review by Robert Pivec's group outlines similar candidacy principles: severe hip pain that limits function, failure of conservative management, and radiographic confirmation of advanced hip OA, avascular necrosis, or inflammatory arthritis. Surgical success rates are high — patient satisfaction with THA is approximately 90-95%, generally higher than TKA (75-85%).

The single biggest predictor of satisfaction: patient expectations

Kenneth Mathis's John Insall Award study is one of the most cited papers in the TKA literature (over 1,100 citations). It enrolled 253 patients at least 1 year after primary TKA using a validated Knee Function Questionnaire. The study found that whether patients' expectations were met was the single largest determinant of satisfaction — more important than pain scores, range of motion, or complication rates.

Key findings:

• 75% of patients reported that their primary expectation — relief from pain — was met
• Patients who expected to resume high-impact activities (running, skiing, kneeling) were more likely to be dissatisfied even after technically successful surgery
• A second study by Mathis found that patients commonly prioritized walking ability, pain relief with activity, and independence with daily living over athletic performance

Implication for patients: Before surgery, have a candid conversation with your surgeon about which specific activities you expect to return to and which ones remain limited. TKA reliably delivers pain relief, walking ability, and quality-of-life improvement — it does not reliably restore pre-arthritis athletic capacity.

What does recovery actually look like?

For total knee replacement:

• Hospital stay: 1-2 days; same-day discharge is increasingly common for appropriate patients
• Walking with support: Immediately postoperative; full weight bearing on the day of surgery
• Discontinuing walker/cane: Typically 4-6 weeks
• Driving: Usually 4-6 weeks (right knee), 2-4 weeks (left knee, automatic transmission)
• Return to office work: 4-8 weeks
• Return to recreational activity: 3-6 months
• Full pain resolution: Often 3-6 months; improvement continues for up to 2 years

For total hip replacement:

• Restrictions on hip position (avoiding extreme flexion, adduction, internal rotation) for 6-12 weeks to prevent dislocation, depending on approach
• Posterior approach requires most restrictions; anterior approach restrictions are fewer
• Most patients walk without a device by 4-6 weeks

Implant survivorship: how long do replacements last?

Giles Scuderi's survivorship study of 2,629 cemented primary TKAs over 22 years found a 22-year success rate of 90.77% for total condylar designs, with an average annual failure rate of 0.46%. Modern implant registry data suggest 15-20 year survivorship rates of 90-95% for well-selected patients with well-positioned implants.

For younger patients (under 60), survivorship concerns are more significant — revision surgery is more likely before the end of life, and revision TKA is substantially more complex than primary surgery.

Risk factors that affect outcomes

Robert Pivec's research on opioid use prior to THA found that pre-operative opioid use was associated with significantly worse postoperative outcomes — higher pain scores, lower functional scores, and higher complication rates. His obesity data for TKA showed that morbid obesity (BMI ≥40) was associated with higher rates of infection, wound complications, and implant failure compared with normal BMI patients.

Key modifiable risk factors surgeons consider:

• BMI >40: Many surgeons defer surgery until patients reduce BMI to <40 (or <35 for high-risk comorbidities)
• Active smoking: Associated with higher infection and wound healing complications
• Pre-operative opioid use: Strongly predictive of worse outcomes; weaning before surgery is strongly encouraged
• Poorly controlled diabetes (HbA1c >7.5-8): Increases infection risk substantially
• Active joint infection: Absolute contraindication

Questions to ask your doctor

• What are my specific expectations for activity level after surgery, and are those realistic for TKA/THA?
• Am I at the point in my disease progression where surgery is appropriate, or should I try additional non-surgical management?
• What surgical approach do you use for THA (anterior vs. posterior), and what does that mean for my recovery restrictions?
• What is my surgeon's revision rate, and how many arthroplasties does this practice perform per year?
• How will my BMI, diabetes, or prior opioid use affect my candidacy or outcomes?
• Is outpatient or same-day joint replacement an option for me?

The bottom line

Total knee and hip replacement are highly effective procedures for advanced osteoarthritis that has failed conservative management — but satisfaction depends heavily on realistic expectations. The evidence is clear that meeting patients' expectations for pain relief and functional activities of daily living is achievable for most; expectations of returning to high-impact athletic activities after TKA are frequently unmet. Implants last 15-20+ years in most patients, but modifiable risk factors — BMI, smoking, opioid use, diabetes control — should be optimized before surgery to maximize the probability of an excellent outcome.