Total knee arthroplasty (TKA) has been shown to be a durable and reliable method of relieving pain and improving function in patients with end-stage knee arthritis.1-3 Most patients report less pain and increased function following surgery; however, in one study, nearly 20% of patients who underwent TKA remained dissatisfied, and unmet expectations were one of the strongest predictors of dissatisfaction after TKA.4 Other studies have reported similar rates of patient dissatisfaction following primary TKA.5
Identification of the drivers of patient expectations and satisfaction following TKA is essential. A good result following TKA may not necessarily imply a pain-free or symptom-free knee, but may simply be a knee joint that meets a patient’s preoperative expectations.6 Thus, understanding what is important to each patient before TKA and appropriately managing his or her expectations may improve overall patient satisfaction. In today’s healthcare environment, patient satisfaction is being recognized as a measure of healthcare quality that could have an effect on physician and hospital reimbursement.4 Patient factors, such as preoperative mental and general health status and residual postoperative limitations, can affect satisfaction. Here, we identify patient expectations prior to and following primary TKA and evaluate patient factors that affect satisfaction to aid surgeons in communicating to patients what can realistically be expected in terms of pain, range of motion, ambulation, and return to activities following TKA.
Patient Expectations of a Successful TKA
Before realistic expectations can be developed, surgeons need to understand what patients undergoing TKA expect and want from surgery. Bourne et al4 showed that the risk of patient dissatisfaction following TKA was approximately 10 times greater when patient expectations were unmet. Surgeons and patients consider pain relief and improved function to be universal goals of TKA; however, other less intuitive expectations can vary by diagnosis, socioeconomic factors, and preoperative mental health status.6-8 Mancuso et al6 developed and validated a survey to measure patients’ expectations of knee surgery and found that expectations can be diverse. The authors surveyed 161 patients who underwent primary TKA and asked them open-ended questions about their expectations of knee surgery. Patients cited 1,161 expectations that were grouped into 52 categories. These categories were transformed into a specific questionnaire that was validated against a second sample of 163 patients. Pain relief, improved walking ability, and return to sport were among the most common patient expectations. Other expectations included improvement in psychological well-being, sexual activity, social interactions, and gainful employment. Other prospective TKA patients around the world share these expectations.9 In a prospective study of patient expectations of TKA, Yoo et al9 found that patient expectations correlated with sociodemographic and functional factors. The authors reported that pain relief was considered the most important expectation followed by psychological well-being, return to baseline activities, the ability to perform high flexion activities, and return to social activities.
Age, socioeconomic factors, the surgeon's previous surgical experience, sex, and race can influence patient expectations.6,10 Younger patients are more likely to expect improvement in sports performance, whereas older patients are more likely to expect improvement in pain relief and walking ability.6 Additional expectations in terms of improvement are more likely in patients who are employed and those with poorer Western Ontario and McMaster Universities (WOMAC) osteoarthritis index function scores (ie, pain, stiffness, function; odds ratio [OR] = 1.1 per five points) and a low Medical Outcomes Study 36-Item Short Form (SF-36) social score (ie, bodily pain and social function; OR = 0.9 per five points).6,9 Hepinstall et al10 found that patients who lived alone or had a prior history of joint arthroplasty had significantly lower expectations going into surgery, and male sex and Caucasian race were associated with higher expectations. The factors that contribute to a patient’s expectations of TKA are complex.
Patient Factors That Affect Satisfaction
Several studies have examined the patient factors that affect satisfaction following TKA. In a prospective registry study of 8,050 primary, unilateral TKAs, Franklin et al11 showed that functional outcome after TKA varied with patient factors, including knee diagnosis and preoperative physical function. Outcomes have also been shown to be affected by comorbidities, mental health status,12 socioeconomic status, and ethnicity8 (Table 1). Thus, an understanding of how these physical and psychological factors affect pain and function following TKA is necessary to establish realistic patient expectations.
Appropriate patient selection is critical for maximizing clinical results. In a multivariate analysis of 264 patients who underwent TKA for knee osteoarthritis (OA), Merle-Vincent et al13 found that a body mass index (BMI) <27 kg/m2 and radiographic evidence of significant narrowing of the joint space were important preoperative predictors of patient satisfaction. Another study reported increased rates of dissatisfaction among patients with mild to moderate arthritis treated with TKA.14 Schnurr et al15 reported that the risk of dissatisfaction in patients with OA classified as grade 3 or 2 on the Kellgren-Lawrence scale was approximately 2.5 and 3 times higher, respectively, than that of patients with grade 4 OA.
Patients undergoing TKA for mild to moderate knee arthritis may seek revision knee surgery for persistent symptoms and dissatisfaction. Polkowski et al14 evaluated 49 painful TKAs at 1 year postoperatively and found that, in nearly 50%, mild to moderate OA was present at the time of the index arthroplasty. TKA provides reliable and reproducible results in patients with end-stage knee arthrosis, and the indications for TKA, particularly in the younger population, continue to expand.
Preoperative pain, health status, and function can affect postoperative pain and function following primary TKA. In a prospective analysis of 215 patients treated with TKA, Noiseux et al16 found that patients with severe pain on a simple knee range-of-motion test were 10 times more likely to report persistent moderate to severe pain at 6 months postoperatively. In a series of 307 knees treated with TKA, Roth et al17 showed that a patient’s SF-36 general health score was the most predictive patient factor for functional outcome. The authors also found that other factors, including sex, BMI, hypertension, narcotic use, and pulmonary disease, had a substantial effect on postoperative function. Finally, in a series of 412 patients who underwent TKA, Lizaur-Utrilla et al18 showed that a high Charlson Comorbidity Index, worse preoperative Knee Society function scores, and low WOMAC pain scores (ORs = 2.1, 0.7, and 0.3, respectively) were independently more likely to be associated with either revision surgery or clinical failure, which was defined as a Knee Society score of <70 points.
Controversy exists on whether obesity is a contraindication to TKA. Several studies have reported increased risks of surgical complications in this patient population.19,20 In a meta-analysis, Kerkhoffs et al19 showed that, in patients with a BMI >30 kg/m2, infection occurred 1.9 times more often than in patients with a healthy weight, and revision surgery performed for any reason increased 1.3 times. Complications and reoperations negatively affect patient satisfaction.4,20-22 Bourne et al4 reported that the risk of patient dissatisfaction increased 1.9 times in the setting of postoperative complications that require readmission. Type 2 diabetes mellitus, a comorbid condition in patients who are obese, has also been shown to lead to poorer functional outcomes. In a case-matched study of 734 patients who underwent TKA, Robertson et al20 reported that, at 1 year postoperatively, patients with type 2 diabetes mellitus had decreased knee flexion and total range of motion and lower Knee Society scores. However, one study has shown that patients who are obese can benefit from TKA. Baker et al21 examined patient-reported outcome measures linked to the United Kingdom National Joint Registry and stratified these results based on BMI. The authors showed that the change in patient-reported outcomes was similar in patients regardless of BMI, but wound complications were significantly increased in patients with a BMI of 40 to 60 kg/m2 compared with those with a BMI <25 kg/m2. Consequently, patients who are obese and contemplating TKA should be made aware of the potential risk for poorer functional outcomes and increased complications following TKA.
Psychological well-being can significantly affect postoperative satisfaction.5,7,23 Scott et al5 reported that a low SF-12 mental component score, depression, and pain in other joints was associated with dissatisfaction following TKA. Gandhi et al23 reviewed a cohort of 1,720 patients undergoing TKA or total hip arthroplasty and reported that, when adjusted for all other variables, a lower preoperative SF-36 mental health score was found to be an independent predictor of patient dissatisfaction following TKA. The authors concluded that interventions to reduce psychological distress before surgery could improve subjective outcomes.
Some studies have found no link between depression and a negative effect on Knee Society scores and satisfaction following TKA. Pérez-Prieto et al7 found that the level of improvement from preoperative levels was similar in patients with or without depression, and more importantly, these authors found that depression did not affect overall satisfaction rates. Thus, the effect that depression has on patient satisfaction with TKA remains unknown. Development of psychometric tools to identify at-risk patients may allow for preoperative intervention, such as education and counseling, and help establish realistic patient expectations before TKA.
Socioeconomic status has also been shown to impact satisfaction. Barrack et al8 found that satisfaction correlated with socioeconomic (eg, income, education, employment) and demographic (eg, sex, ethnicity) factors. They found that patients with incomes <$25,000 were more likely to be dissatisfied following TKA and have more functional limitations. Compared with men, women were found to be less likely to be satisfied and more likely to have functional limitations. Finally, minority patients had more functional limitations than nonminority patients following TKA. In a cohort of Scottish patients, Clement et al24 found that the most socially “deprived” patients (based on the Scottish Index of Multiple Deprivation) underwent surgery at a younger age and were more likely to be female, have more comorbidities, and have poor mental health. Although the authors did not establish a direct link between low income and patient dissatisfaction, they found that lower Oxford knee and SF-12 mental component scores, back pain, and the presence of four or more comorbidities were associated with lower rates of satisfaction. Consequently, patient factors such as mental health, general health status, and socioeconomic factors can affect overall satisfaction (Table 1). The interplay between these factors can be unique to each patient and illustrates the complexity of the drivers of satisfaction following TKA.
Physical Function and Limitations Following TKA
Primary TKA is one of the most effective surgical procedures in medicine and is associated with significant reduction in pain, proven health utility, and improvement in quality-adjusted life years.1 However, residual pain, functional deficits, and other unmet expectations are among the main reasons for patient dissatisfaction. Therefore, surgeons need to be familiar with realistic, achievable levels of pain relief and function to aid patients in establishing realistic expectations before TKA.
Although most patients achieve significant pain relief after TKA, the process is gradual, variable, and often incomplete.22,25 In a study of 112 patients with osteoarthritis who were surveyed about their expected outcomes after knee surgery, Mannion et al26 reported that 85% of patients expected to be pain free following TKA, but only 43% of patients reported no pain at final follow-up. In a study of 116 patients treated with TKA, Brander et al22 reported that 18% and 13% of patients reported significant postoperative knee pain at 6 and 12 months, respectively. A similar trend of decreasing knee pain (based on WOMAC pain scores) at different time points was reported in other studies2,25-27 (Table 2). Although many patients initially report good or excellent results following TKA, many later admit to continued, albeit improved, pain. Therefore, prospective TKA patients should be counseled that, although improved levels of pain can be expected following surgery, the extent of pain relief can be gradual and sometimes inconsistent.
Residual pain, stiffness, prosthetic noises, and difficulty with stairs commonly persist for up to 24 months following TKA.2,22,25 In a multicenter study, Parvizi et al28 surveyed 661 TKA patients younger than 60 years and found that nearly one third reported residual symptoms and functional limitations after TKA. These symptoms included pain (33%), stiffness (41%), swelling (33%), grinding or other noises (33%), and difficulty with stairs (54%). Patients may also experience common symptoms, such as prosthetic noise, numbness or decreased sensitivity around the surgical site, and feelings that the replaced knee is not normal. Sharkey and Miller29 surveyed 49 patients who underwent TKA and reported that 69% and 71% of patients reported noise and numbness, respectively. If patients are unprepared, these common and unavoidable consequences of surgery and the inability of current TKA designs to reproduce normal knee kinematics can become a source of patient disappointment and dissatisfaction.
Improvement in function and return to activities can be unpredictable following TKA.25 Although most patients can achieve better function following TKA, studies have shown that they rarely approach prearthritic functional levels and those of age-matched control subjects.27 In the study by Parvizi et al,28 only 66% of patients reported that their knees felt normal after TKA. However, Hawker et al2 reported that most of the surveyed Medicare patients had less pain, improved walking ability, required less medication, and >50% had little or no difficulty performing any of the 17 activities assessed with the WOMAC osteoarthritis index at 2 to 7 years after TKA. Most series report gradual improvement in function over time in most patients (up to 90%).2,28 Using the WOMAC function scores as a reference, patients can expect improvement in functional scores from a mean of 45 points preoperatively to a mean of 70 points at 12 months postoperatively.25 Thus, although TKA can improve overall function in most patients, a significant number of patients can fail to achieve levels of desired function.
Quadriceps function may be limited for up to 2 years in patients recovering from TKA. It is common for patients recovering from TKA to struggle with activities such as stairs, kneeling, and squatting.2,27,30,31 Even walking ability, which is important to patients, can remain limited. Ouellet and Moffet32 compared healthy patients with those who underwent TKA and found that the TKA group had difficulty with a Timed Up and Go test, covered less distance during a 6-minute walk test, walked at a slower pace, and took longer to negotiate stairs at all intervals ranging from 2 months to 5 years following surgery. Additionally, Rossi et al30 showed that tasks, such as going up and down stairs, heavy domestic duties (eg, vacuuming, cleaning), and getting in and out of the bath, remained challenging to patients after knee surgery. Several studies have reported that >50% of patients with well-functioning TKA continue to have difficulty with stairs, kneeling, and squatting for >1 year following surgery.28,30,33
Return to sports is another functional goal that is highly valued by patients undergoing TKA.31,34 Patients with knee arthritis want to return to a wide variety of sports including golf, dancing, swimming, skiing, and tennis.31,34 In a study of 101 patients’ expectations of TKA, Meneghini et al35 reported that 19% of patients underwent the procedure primarily to return to sport-related activities. Although return to low-impact activities is feasible and recommended following TKA, return to preoperative levels of sporting activities cannot be guaranteed. In a study of TKA outcomes, Dahm et al36 surveyed 1,206 patients regarding their participation in 40 different athletic activities. The authors reported that the mean University of California Los Angeles activity level score was 7.1 points at an average of 5.7 years after surgery. This reflects regular participation in activities such as bicycling but not activities more strenuous than golf or bowling. The authors also found that men younger than 70 years had higher University of California Los Angeles scores, Knee Society scores, and self-assessment of activity than did peers. Jones et al33 compared the differences between actual and expected return to leisure activities following TKA and found that patients underperformed their expected activity level by an equivalent of walking 14 miles less per week. Other studies have also shown that patients either choose not to return to desired sporting activities or showed an overall decline in participation after TKA because of residual pain.34 Consequently, evidence-based counseling of patients before TKA can help them to establish realistic expectations and minimize disappointment postoperatively. Commonly reported limitations following TKA are outlined in Table 3.
Management of Patient Expectations
In today’s competitive healthcare environment, patients contemplating TKA are bombarded with images and perceptions of rapid recovery, return to normal life, and high levels of function following TKA. This undoubtedly fuels unrealistic expectations that can contribute to patient dissatisfaction. However, data show that appropriate management of patient expectations can positively influence patient satisfaction.31,37 In a literature review, Culliton et al38 found that fulfillment of postoperative expectations did predict patient satisfaction, but the nature of the preoperative expectation (eg, amount of pain relief and functional improvement at 1 year) did not predict satisfaction. In a study of 102 patients’ preoperative expectations of TKA and postoperative satisfaction, Nilsdotter et al37 found that although 80% of patients were satisfied with their eventual functional recovery, 93% were satisfied with the surgery at 5 years postoperatively. This suggests that patients with less than complete pain relief and function following TKA can be satisfied if expectations are appropriately managed. Therefore, patients should be counseled that residual symptoms, such as mild pain, swelling, and stiffness, are likely despite the reliability and reproducibility of TKA for relieving pain and improving function in patients with knee arthritis. Additionally, the recovery process can take up to 2 years, and the surgical knee is not likely to feel or function like the natural knee. These discussions must occur as part of the informed consent procedure before surgery.
Surgeons must define and challenge the drivers of what qualifies as a successful TKA. Traditional measures of a successful TKA, such as Knee Society scores and implant survivorship, are poorly correlated with patient ratings of health status, particularly in subjective domains, including pain, function, and quality of life.3 As a result, there has been a recent shift in focus to patient-reported outcome measures.3 The Knee Society recently introduced a new scoring system that takes into account patient satisfaction and specific physical activities to help more accurately quantify the successes and failures of modern TKA.39 Finally, surgeons’ traditional goals of surgery, such as alignment, ligament balance, component rotation, and patellar tracking, often have been related to implant survivorship rather than patient satisfaction.40 Lee and Lotke40 showed that a surgeon’s intraoperative impression of the quality of a TKA did not correlate with postoperative Knee Society scores. Thus, the optimal individual alignment, laxity, and ligament balance of today’s TKA designs are yet to be determined.
Although TKA has been shown to be durable, reliable, and reproducible in relieving pain and improving function in patients with end-stage arthritis of the knee, nearly 20% of patients remain dissatisfied following surgery. Although the drivers of patient satisfaction are complex and multifactorial, unmet expectations have been shown to be a significant source of dissatisfaction. However, common causes of dissatisfaction, such as residual pain, stiffness, and failure to return to high levels of function, can be expected following normal and well-performed TKAs. Therefore, careful patient selection, identification of patients at risk for dissatisfaction, and the establishment of realistic patient expectations can minimize disappointment following TKA.
Evidence-based Medicine: Levels of evidence are described in the table of contents. In this article, references 5-7, 9, 10, 12, 13, 18, 33, and 37 are level I studies. References 1-4, 11, 15-17, 19, 21-27, 34, 39, and 40 are level II studies. References 8, 14, 20, 28-30, 35, 36, and 38 are level III studies. References 31 and 32 are level IV studies.
References printed in bold type are those published within the past 5 years.
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40. Lee GC, Lotke PA: Can surgeons predict what makes a good TKA? Intraoperative surgeon impression of TKA quality does not correlate with Knee Society scores. Clin Orthop Relat Res 2012;470(1):159–165.