Abstract
Introduction:
Total knee arthroplasty (TKA) is a highly effective intervention for enhancing function and quality of life in cases with advanced knee osteoarthritis. Although multiple factors have been identified as influencing TKA outcomes, it remains challenging to accurately predict which patients will experience dissatisfaction postoperatively, thereby complicating efforts to optimize their management. This study aimed to evaluate the patient satisfaction outcome after TKA done at our hospital's joint replacement registry using the updated Knee Society Scoring System.
Method:
This retrospective observational study was conducted on 900 cases who underwent a TKA. The same surgeon consultant, head of the department, performed all the surgeries.
Results:
SF-12 scores and total new knee society scoring (satisfaction subscale, expectation subscale, function activity subscale, and total score) were markedly higher at the end of follow-up than at the baseline (P < 0.05). A negative correlation was found between new knee society scoring, and age and body mass index(P < 0.05). A positive correlation was found between new knee society scoring, and duration of follow and SF-12 as P < 0.05. New knee society scoring was markedly higher in men than women (P = 0.011). New knee society scoring was markedly different among causes of arthroplasty (P = 0.005).
Discussion:
An overall satisfaction rate was there among the studied cases regarding SF-12 score, which measures the activity and mentality of the cases postoperatively; in addition, most of the studied group show a notable improvement in new knee society score.
Total knee arthroplasty (TKA) is a highly effective intervention for enhancing function and quality of life in cases with advanced knee osteoarthritis.1 Each year, more than 600,000 TKA procedures are performed in the United States.2 Although notable progress has been made in areas such as patient selection, surgical techniques, and implant design, studies have shown that satisfaction rates following TKA range from only 82% to 89%.3-5 These findings imply that a considerable proportion of cases do not achieve optimal pain relief and functional recovery after TKA.6
Factors such as preoperative expectations, prosthesis type, sex, age, and psychological status have been proposed as contributors to the relatively low rates of patient satisfaction.7 Nevertheless, the absence of a universally accepted questionnaire or assessment tool for measuring satisfaction has led to variability in identifying reliable preoperative predictors.8
To gain a clearer understanding of the patient's experience, evaluating patient-reported outcome measures (PROMs), particularly satisfaction, is essential. From a patient-centered standpoint, a TKA can be considered successful only if the patient is satisfied with the results.9
The evaluation of surgical outcomes has increasingly emphasized patient satisfaction and PROMs, reflecting a paradigm shift toward incorporating the patient's perspective rather than relying solely on surgeon-derived assessments.10 In a recent review, Kahlenberg et al11 highlighted that the most commonly employed method for assessing satisfaction involves a single global question rated on an ordinal scale (e.g., “very satisfied,” “somewhat satisfied,” “dissatisfied,” “very dissatisfied”). However, alternative approaches have also been reported in the literature, including the use of varied Likert-type scales and multi-item questionnaires designed to capture different dimensions of patient satisfaction.
The variety of satisfaction reporting methods and scoring systems complicates the identification of cases who are genuinely dissatisfied with the outcomes of TKA.12 In addition, limited research has compared the different approaches to measure patient satisfaction or explored the relationship between the focus of restoration and postoperative scoring systems.13
The updated “Knee Society Knee Scoring System,”’ introduced in 2011, was designed to address the limitations of its predecessor, enhancing both responsiveness and reliability. This new system integrates both physician-derived and patient-exhibited components, combining the objective aspects of the previous system with the patient's subjective perspective. It includes evaluations of patient satisfaction, expectations, and functional activities, providing a deeper understanding of patient outcomes and aiming to better accommodate a younger and more diverse population undergoing TKA.14
Health-related quality of life is universally recognized as an essential outcome measure in chronic conditions, including knee osteoarthritis. The SF-12 score, derived from the longer SF-36 score, includes physical and mental component summary (PCS, MCS) scores and serves as a validated tool for assessing quality of life. One advantage of the SF-12 is its reduced burden on cases, as it contains 24 fewer questions than the SF-36.15
This study aimed to assess patient satisfaction outcome following TKA performed at our hospital, using the updated Knee Society Knee Scoring System.
Methods
This retrospective observational study was conducted on 900 cases, both sexes, and underwent TKA. The study was done at Gamal Abdel-Nasser Insurance Hospital, Alexandria, Egypt from January 2017 to January 2025 after approval from the Ethical Committee. An informed written consent was obtained from the cases.
Exclusion criteria were revision cases, vascular or neurological problems in the same limb, or nonambulant cases. All surgeries were performed by the same surgeon Dr. Abd Alwanis, MD, consultant and head of orthopaedic surgery department and joint replacement team.
Patient Satisfaction Measurement Tools
The Knee Society Task Force restructured the updated Knee Society Scoring System to encompass two distinct but complementary domains. The first consists of objective parameters, derived from surgeon-based assessments rooted in the original Knee Society Scoring System (KSS) framework, addressing key technical aspects, such as pain, range of motion, alignment, and joint stability. The second domain incorporates subjective parameters, capturing patient-reported outcomes related to knee function, satisfaction, and the degree to which postoperative expectations are fulfilled—thereby acknowledging the integral role of patient perception in evaluating surgical success.16
To ensure a comprehensive evaluation of postoperative physical and mental health, all participants were asked to complete the SF-12 questionnaire. A nurse, independent of the surgical team, was present during administration to offer clarification when needed and to verify that each item was thoroughly and accurately completed, thereby minimizing the risk of incomplete or biased responses.17
Quality of Life Assessment Using the Short Form-12 Questionnaire
The SF-12 consists of 12 questions (with the appendix available online through ArticlePlus) derived from each of the eight domains of the SF-36.12,13 The responses from the SF-12 can be extracted from the SF-36 questionnaire, providing results that are comparable to those obtained when the SF-12 and SF-36 are administered separately. The SF-12 results are exhibited as PCS and MCS scores. The assessment was conducted preoperatively and at the end of the follow-up period Appendix, http://links.lww.com/JG9/A499.
All patients were followed up through a standardized protocol that included scheduled outpatient clinic visits and telephone contact for those who did not attend their appointments at 3, 6 weeks, 3, and 6 months. The midterm outcomes of TKA at our hospital were assessed.
Statistical Analysis
Statistical analysis was done using SPSS v26 (IBM). Quantitative data were expressed as means and SD, and comparisons between the two groups were made using an unpaired Student t-test, whereas comparisons among three groups were done using an analysis of variance (F) test. Qualitative data were presented as frequencies and analyzed using the chi-square test. Correlations between variables were assessed using the Pearson correlation coefficient. A two-tailed P of <0.05 was considered statistically significant.
Results
The mean value ± SD of age was 65.9 ± 10.7 years; 397 (44.1%) were men and 503 (55.9%) women. Regarding body mass index (BMI), 209 cases (23.2%) were normal weight, 538 cases (59.8%) were overweight, 153 cases (17.0%) were obese. Right side was present in 473 cases (52.6%) and left side in 427 cases (47.4%). Regarding the type of deformity, varus was present in 724 cases (80.4%), valgus was present in 176 cases (19.6%), flexion deformity +varus was present in 640 cases (71.1%), and flexion + valgus was present in 97 cases (10.8%). Cause of arthroplasty was osteoarthritis in 805 cases (89.4%), rheumatoid arthritis in 64 cases (7.1%), and posttraumatic in 31 cases (3.5%). Type of surgery was Posterior Stabilized (PS) TKA in 807 cases (89.7%) and constrained condylar knee prosthesis in 93 cases (10.3%). The mean value ±SD of duration of follow-up was 22.9 ± 18.3 months (Table 1).
Table 1.
Basic Characteristic Feature of the Studied Cases
| Factor or Variable | (N = 900) |
| Age (yr) | 65.9 ± 10.7 |
| <60 | 181 (20.1%) |
| >60 | 719 (79.9%) |
| Sex | |
| Male | 397 (44.1%) |
| Female | 503 (55.9%) |
| BMI | |
| Normal weight | 209 (23.2%) |
| Overweight | 538 (59.8%) |
| Obese | 153 (17.0%) |
| Laterality | |
| Right | 473 (52.6%) |
| Left | 427 (47.4%) |
| Type of deformity | |
| Varus | 724 (80.4%) |
| Valgus | 176 (19.6%) |
| Flexion deformity + varus | 640 (71.1%) |
| Flexion + valgus | 97 (10.8%) |
| Cause of arthroplasty | |
| Osteoarthritis | 805 (89.4%) |
| Rheumatoid arthritis | 64 (7.1%) |
| Posttraumatic | 31 (3.5%) |
| Type of surgery | |
| PS total knee arthroplasty | 807 (89.7%) |
| Constrained condylar knee prosthesis | 93 (10.3%) |
| Duration of follow-up, mo | 22.9 ± 18.3 |
BMI = body mass index
Data are presented as mean ± SD or frequency (%).
SF-12 scores and total new knee society scoring (satisfaction subscale, expectation subscale, function activity subscale, and total score) were markedly higher at the end of follow-up than at the baseline (P < 0.05) (Table 2). A negative correlation was found between new knee society scoring, and age and BMI as P < 0.05. A positive correlation was found between new knee society scoring, and duration of follow-up and SF-12 as P < 0.05 (Table 3).
Table 2.
Comparison Between the SF-12 Scores of Two Items of Score and Total New Knee Society Scoring at Baseline and at the End of Follow-up Postoperatively
| Factor or Variable | Baseline | At the End of Follow-up | t | P |
| SF-12 scores | ||||
| Physical | 12.1 ± 2.1 | 16.1 ± 2.01 | 3.98 | 0.012a |
| Mental | 17.9 ± 3.52 | 21.2 ± 2.32 | 4.02 | 0.003a |
| Total | 30.0 ± 3.05 | 37.3 ± 2.85 | 4.0 | 0.0041a |
| Total new knee society scoring | ||||
| I. Satisfaction subscale (40 points) | 17.3 ± 4.21 | 35.2 ± 10.2 | 5.32 | 0.0021a |
| II. Expectation subscale (15 points) | 6.12 ± 1.25 | 13.2 ± 2.01 | 4.25 | 0.003a |
| III. Function activity subscale (100 points) | ||||
| Walking and standing (30 points) | 10.6 ± 1.65 | 25.6 ± 3.58 | 6.02 | 0.001a |
| Standard activities (30 points) | 9.5 ± 3.02 | 24.1 ± 4.01 | 5.85 | 0.005a |
| Advanced activities (25 points) | 7.33 ± 1.71 | 19.8 ± 3.05 | 6.89 | 0.006a |
| Discretionary activities (15 points) | 2.11 ± 1.24 | 12.1 ± 2.65 | 7.01 | 0.001a |
| Total score | 52.96 ± 17.2 | 130 ± 22.6 | 6.09 | 0.001a |
t = paired t-test
Significant P value ≤0.05.
Data are presented as mean ± SD.
Table 3.
Correlation Between Final New Knee Society Knee Scoring at the End of Follow-up and Other Clinical Data
| New knee society scoring# | Correlation coefficient | P |
| Age | −0.426 | 0.008a |
| BMI | −0.511 | 0.009a |
| Duration of follow-up | 0.398 | 0.035a |
| SF-12 | 0.732 | 0.0003a |
BMI = body mass index, SF-12 = 12-item Short Form Survey
Significant P value ≤0.05.
New knee society scoring was markedly higher in male than in female cases (P = 0.011). New knee society scoring was markedly different among causes of arthroplasty (P = 0.005) (Table 4).
Table 4.
Effect of Sex and Laterality on the Final New Knee Society Scoring
| Factor or Variable | New knee society scoring | Test | P |
| Sex | |||
| Male | 138.6 ± 20.9 | t-test = 2.57 | 0.011a |
| Female | 122.1 ± 19.1 | ||
| Cause of arthroplasty | |||
| Osteoarthritis | 140.3 ± 21.6 | ANOVA = 6.25 | 0.005a |
| Rheumatoid arthritis | 125.2 ± 20.3 | ||
| Posttraumatic | 105.2 ± 18.6 |
ANOVA = analysis of variance
Significant P value ≤0.05.
Discussion
Achieving high levels of patient satisfaction following TKA continues to be difficult. Although TKA is generally successful, approximately 20% of cases report dissatisfaction. Key factors contributing to this dissatisfaction include persistent pain and restricted functionality.4
This study evaluated patient satisfaction following TKA using the Updated Knee Society Scoring System (2011). Most patients achieved high satisfaction, aligning with international literature reporting improved pain relief and function after TKA.
The use of PROMs such as the updated KSS allows a more comprehensive understanding of outcomes. Unlike standard systems, the 2011 version includes satisfaction, expectations, and functional activities, capturing the patient's full recovery experience. Pain relief was the strongest determinant of satisfaction, followed by function and range of motion.
Our results revealed that SF-12 scores and total new knee society scoring (satisfaction subscale, expectation subscale, function activity subscale, and total score) were markedly higher at the end of follow-up than at the baseline. A negative correlation was found between new knee society scoring, and age and BMI. A positive correlation was found between new knee society scoring, and duration of follow-up and SF-12. New knee society scoring was markedly higher in male than in female cases. New knee society scoring was markedly different among causes of arthroplasty.
The updated KSS provides notable advantages in evaluating the outcomes of TKA from a modern perspective. In accordance with the increasing emphasis on patient-exhibited outcome measures (PROMs)—now widely adopted across various medical specialties—numerous elements within the subscales of the new scoring system are based on patient self-assessment.18
In addition, each domain of the subjective score, including function, expectations, and satisfaction, reflects the individual patient's values and perspectives regarding TKA outcomes. This represents a notable departure from the standard KSS, based on the understanding that musculoskeletal treatment outcomes involve compromises best evaluated by the cases themselves.19
This paradigm shift introduces challenges in creating a universally applicable outcome score that can be rigorously analyzed statistically. The heterogeneity of the TKA population—spanning differences in age, sex, and lifestyle—complicates the formulation of a standardized set of activities that resonate with or apply to a broad patient base.20 McCalden et al.21 observed a statistically significant improvement in the KSS, with the most pronounced gains seen in cases younger than 55 years (mean change of 78.9 years), followed by those aged 55 to 70 years (76.0 years), and those older than 70 years (69.0 years). This trend was also evident in the KSS subscales, particularly the clinical and functional domains. A similar, although not statistically significant, pattern was noted in SF-12 scores.
Franklin et al22 demonstrated that the post-TKA SF-12 functional scores exhibited bimodal and flat distributions across all BMI groups. Interestingly, cases with a BMI below 30 and those between 30 and 40 showed comparable distributions and exhibited similar improvements in SF-12 scores at 12 months.
Giesinger et al23 identified a negative effect of BMI on postoperative satisfaction scores. By contrast, Liu et al7 found minimal difference in BMI between comparison groups, implying that overweight or obese cases may not necessarily report lower satisfaction following TKA.
Lange et al24 suggested that younger cases (<55 years) tend to have lower satisfaction rates postoperatively, although rates remained above 80%. Conversely, studies by Lizaur-Utrilla et al25 and Clement et al26 found that being younger than 55 years was not an independent predictor of functional outcomes or satisfaction.
Robertsson et al27 found no association between satisfaction and age among cases with osteoarthritis but did observe reduced satisfaction among older cases with rheumatoid arthritis. Conversely, Noble et al28 exhibited that patient satisfaction tends to decrease with advancing age.
Brandes et al29 highlighted that TKA led to notable improvements and excellent clinical outcomes for most cases. However, despite these improvements, many cases did not achieve the same level of physical activity as healthy individuals. The level of activity after surgery appeared to be more influenced by preoperative physical activity habits than by the surgery itself.
The low complication rate demonstrates reliable outcomes. However, complications markedly affected satisfaction, emphasizing the role of postoperative care and rehabilitation.
A major strength of this study is the use of the updated KSS (2011), which provides a modern, patient-centered assessment framework. The large sample and real-world data from an Egyptian arthroplasty registry further strengthen the findings.
However, there are several limitations. It was conducted at a single center, potentially limiting generalizability. The study population may not reflect broader demographics, introducing selection bias. The study only evaluated whether postoperative expectations were met, without measuring preoperative expectations. Short follow-up period may not capture the full trajectory of pain relief or functional improvement, both of which could influence satisfaction. Therefore, we recommend further multicenter research with extended follow-up periods to clarify the role of postoperative complications requiring hospitalization in patient dissatisfaction.
Conclusion
Total knee arthroplasty performed at Gamal Abdel-Nasser Insurance Hospital achieved a high rate of patient satisfaction as measured by the Updated Knee Society Scoring System (2011). Most patients experienced notable pain relief, functional recovery, and improvement in quality of life. Residual dissatisfaction was mainly associated with stiffness, limited motion, or unmet expectations. Using the updated KSS (2011) enabled a comprehensive, patient-centered evaluation that reflects both clinical and personal recovery outcomes and is recommended for future arthroplasty assessments.
Footnotes
Neither of the following authors nor any immediate family member has received anything of value from or has stock or stock options held in a commercial company or institution related directly or indirectly to the subject of this article: Abd Al Wanis and Dr. Adam.
All authors contributed to the study conception and design. Material preparation, data collection, and analysis were performed by (Dr. Adam), and (Abd Al Wanis). The first draft of the manuscript was written by Dr. Adam and Abd Al Wanis. All authors commented on previous versions of the manuscript. All authors read and approved of the final manuscript.
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