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Subjective evaluation before and after total knee arthroplasty using the 2011 Knee Society Score
The Knee 23 (2016) 964–967
Contents lists available at ScienceDirect
The Knee
Subjective evaluation before and after total knee arthroplasty using the 2011 Knee Society Score Yuichi Kuroda a, Tomoyuki Matsumoto a,⁎, Koji Takayama a, Kazunari Ishida b, Ryosuke Kuroda a, Masahiro Kurosaka a a b
Department of Orthopaedic Surgery, Kobe University Graduate School of Medicine, Kobe, Japan Department of Orthopaedic Surgery, Kobe Kaisei Hospital, Kobe, Japan
a r t i c l e
i n f o
Article history: Received 14 November 2015 Received in revised form 26 May 2016 Accepted 16 June 2016 Keywords: Total knee arthroplasty The 2011 Knee Society Knee Scoring System Subjective outcome Patient satisfaction Patient expectation
a b s t r a c t Background: Patient satisfaction has been recognized as an important evaluation of total knee arthroplasty (TKA). Therefore, the 2011 Knee Society Knee Scoring System (2011 KSS) was developed in order to quantify patient satisfaction, expectations, and physical activities following TKA. However, very few reports have described subjective evaluation before TKA using the 2011 KSS, as the scoring system is still relatively new. Therefore, the degree of improvement and change over time after TKA has not been evaluated. Methods: Forty-nine consecutive patients (79 knees) with a mean age of 74.8 ± 7.3 years were prospectively included in the study and evaluated preoperatively and one year postoperatively. The following questions were assessed using the 2011 KSS: (1) Do patient-derived clinical scores improve after TKA? (2) Do patientderived clinical scores before TKA correlate with those after TKA? and (3) Are there correlations among each category of the 2011 KSS score? Results: The majority of categories showed significant improvements after TKA. The preoperative functional activities score was positively correlated with the postoperative symptoms, functional activities, and objective score. Each category of the 2011 KSS score correlated with others postoperatively. Conclusions: All patient-derived scores except for patient expectation significantly improved postoperatively. The more functionally active patients before receiving TKA acquired more successful objective and functional outcomes, and the postoperative knee condition was directly influenced by each subscale of the 2011 KSS. © 2016 Elsevier B.V. All rights reserved.
1. Introduction Total knee arthroplasty (TKA) is a well-established surgical procedure that generally results in pain relief, improved physical function, and high level of patient satisfaction. Beneficial results are achieved in most patients after TKA, and advanced surgical techniques and prosthesis design have led to improved outcomes [7,13]. Although the benefits of TKA from the physician's viewpoint, such as range of motion (ROM) and radiographic outcomes, have previously been studied [7,13], the benefits of the procedure from the patient's point of view are currently unknown. Patient satisfaction has been recognized as an important basis of evaluation in TKA [1,3,10], but it is very difficult to quantify and evaluate patient satisfaction and subjective knee function after TKA. In comparison, physician-derived scores can be quantified with ease, but these are poorly related to patient-reported scores [4]. As ⁎ Corresponding author at: Department of Orthopaedic Surgery, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan. Tel.: +81 78 382 5985; fax: +81 78 351 6944. E-mail address: [email protected] (T. Matsumoto).
http://dx.doi.org/10.1016/j.knee.2016.06.008 0968-0160/© 2016 Elsevier B.V. All rights reserved.
a result, patient-derived outcome scales have become increasingly important [14]. Previously, the visual analog scale (VAS) and Western Ontario and McMasters Universities Osteoarthritis Index (WOMAC) have been used to evaluate patient satisfaction and subjective knee function [2], despite these instruments not being scoring systems to specifically measure patient satisfaction and knee function after TKA [4]. In 2012, the Knee Society developed a new Knee Society knee scoring system – The 2011 Knee Society Knee Scoring System (2011 KSS) – in order to quantify patient satisfaction, expectations, and physical activities following TKA [16,19]. However, the literature on the use of the 2011 KSS in evaluating patients' subjective outcomes after TKA is limited due to its novel nature [8,12,15,5]. Furthermore, very few reports have described subjective evaluation before TKA using the 2011 KSS [5], and the degree of improvement and change over time after TKA have not been evaluated. Therefore, in this study, the following questions were assessed using the 2011 KSS: (1) Do patient-derived clinical scores improve after TKA? (2) Do patient-derived clinical scores before TKA correlate with those after TKA? and (3) Are there correlations among each of the following
Y. Kuroda et al. / The Knee 23 (2016) 964–967 Table 1 Comparisons of preoperative and postoperative scores. The 2011 KSS categories
Pre-operation
Post-operation
P
Objective knee indicators Symptoms Satisfaction Expectations Functional activities
67.7 ± 12.6 8.6 ± 5.4 15.3 ± 7.9 12.3 ± 2.5 43.0 ± 18.6
92.3 ± 5.5 18.8 ± 4.5 25.6 ± 7.3 11.0 ± 2.7 65.8 ± 19.0
b0.001 b0.001 b0.001 b0.001 b0.001
The data are expressed as mean ± SD values.
categories of the 2011 KSS score when administered postoperatively: symptoms, patient satisfaction, patient expectations, and functional activities? 2. Materials and methods From May 2012 to December 2013, 75 consecutive patients (79 knees) who had undergone TKA (32 knees: P.F.C. Sigma, DePuy Orthopaedics, Inc., Warsaw, IN; 47 knees: e-motion, Aesculap Inc., Center Valley, PA) were prospectively enrolled in the study. The patient cohort consisted of 63 female and 12 male subjects with a mean age of 74.8 ± 7.3 years (mean ± standard deviation). Posterior-stabilizing prostheses and cruciate-retaining implants were used in 54 knees and 25 knees, respectively. Seventy-two knees had a diagnosis of osteoarthritis, two knees had a diagnosis of osteonecrosis, and five knees had a diagnosis of rheumatoid arthritis. Patients with bone defects requiring bone grafting or augmentation, revision arthroplasties, and those who underwent an alternative surgical procedure during the study were excluded. The patient-derived score of the 2011 KSS has the following four categories: symptoms, patient satisfaction, patient expectations, and functional activities (e.g., walking/standing, standard activities, advanced activities, and discretionary activities). The objective knee indicators score of the 2011 KSS, completed by the surgeon,
965
includes alignment, instability, and joint motion. The 2011 KSS, which incorporates both the preoperative and postoperative versions, shows that the only difference between the two versions is the patient expectations category [16,19]. The 2011 KSS questionnaires were completed on admission for TKA and at a one-year outpatient appointment following TKA. An institutional review board approved the survey. Patients provided informed consent prior to participating in the study and no patients were excluded after informed consent. The 2011 KSS scores, including preoperative objective knee indicators, were compared with those at one year postoperatively, and the correlations between the preoperative and postoperative scores in each category were evaluated. Furthermore, the correlations among each category of the 2011 KSS score were evaluated one year after TKA. Statview 5.0 (Abacus Concepts Inc., Berkeley, CA, USA) was used for statistical analysis. The differences between preoperative and postoperative scores were analyzed using paired Student's t-tests. Pearson correlation coefficient tests were used to examine the correlations of the 2011 KSS scores; differences with P b 0.05 were considered statistically significant. 3. Results 3.1. Comparisons of preoperative and postoperative scores All categories, except for the patient expectation score of the 2011 KSS, showed significant improvements after TKA (P b 0.001) (Table 1). The postoperative patient expectation score was significantly lower than the preoperative score (P b 0.001) (Table 1). 3.2. Correlations between preoperative and postoperative scores The preoperative functional activities score was positively correlated with the postoperative symptoms, the functional activities, and the objective knee indicators score (Figure 1 and Table 2). The preoperative expectations score was positively correlated with the postoperative symptoms, functional activities and the objective knee indicators score. There were no correlations related to the preoperative and postoperative satisfaction scores (Table 2).
Figure 1. The relationships between preoperative functional activities score and each of postoperative functional activities, symptoms, and functional activities score of the 2011 Knee Society Scoring System.
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Y. Kuroda et al. / The Knee 23 (2016) 964–967
Table 2 Correlations of preoperative and postoperative scores. Post-operation Pre operation
Objective knee indicators
Symptoms
Satisfaction
Expectations
Functional activities
Objective knee indicators Symptoms Satisfaction Expectations Functional activities
0.07 (0.540) 0.08 (0.501) 0.07 (0.553) 0.27⁎ (0.018) 0.32⁎ (0.004)
−0.08 (0.490) 0.06 (0.597) 0.10 (0.386) 0.27⁎ (0.016) 0.26⁎ (0.021)
0.10 (0.399) 0.15 (0.181) 0.12 (0.274) 0.17 (0.127) 0.14 (0.216)
0.14 (0.227) 0.07 (0.541) −0.08 (0.470) 0.14 (0.204) 0.22 (0.056)
0.17 (0.126) 0.08 (0.495) −0.05 (0.662) 0.23⁎ (0.038) 0.46⁎ (b0.001)
The data are expressed as r-value (P-value) by Pearson's correlations. ⁎ P b 0.05.
3.3. Correlations among each category of postoperative score There were significant correlations in all the categories of postoperative scores (r-range 0.42–0.58) (Figure 2).
4. Discussion The preoperative and postoperative patient-derived scores of patients who underwent TKA using the 2011 KSS were investigated. The most significant findings were that all patient-derived scores except for patient expectation significantly improved postoperatively, and the preoperative functional activities score was positively correlated with postoperative symptoms, functional activities, and objective knee indicators scores. Furthermore, all the categories of the 2011 KSS correlated mutually at the one-year follow-up appointment. The proportion of younger and more physically active patients who undergo TKA has increased in recent times [9]. In order to accommodate these changes, the 2011 KSS was developed from the conventional Knee
Society scoring system (1989), but only included three subjective items: pain, walking ability, and ability to climb stairs [6] to better characterize the expectation, satisfaction, and physical activities of patients who underwent TKA. The 2011 KSS was reported to be a reliable, internally consistent, and responsive questionnaire with construct validity when used to assess the outcomes of TKA patients [5]. Matsuda et al. reported that surgeons who performed TKA overestimated symptoms and function, and there was a weak relationship between patient-derived and physician-derived scores on postoperative pain and function using this scoring system [12]. Although previous studies have reported relatively low scores of each category of the 2011 KSS for patients who underwent TKA, these studies did not evaluate preoperative patient-derived scores [12,15]. Therefore, the degree of improvement and change over time after TKA is unknown. In the present study, all patient-derived scores except for patient expectation significantly improved postoperatively, indicating that patients may be satisfied after TKA in an alternative way compared with preoperative expectations. Patient expectation scores may appear
Figure 2. The relationships among each category of postoperative the 2011 Knee Society scores.
Y. Kuroda et al. / The Knee 23 (2016) 964–967
to worsen postoperatively, due to a difference in the contents of questionnaires used preoperatively and postoperatively. The preoperative version includes the expectations of postoperative outcomes, whereas the postoperative version refers to superiority or inferiority between the knee condition expected preoperatively and postoperatively. Furthermore, the relationship between patients and surgeons, including the content of informed consent, may affect the expectation score more than the other categories. An inadequate explanation of the operation, including operative procedure, complications, and postoperative rehabilitation, may lead the patients to have disappointing results. A previous study reported that limited postoperative range of motion (ROM) was negatively correlated with postoperative functional activities [12]. However, the present study found that the postoperative objective indicator was positively correlated with preoperative functional activities, which in turn were positively correlated with the postoperative functional activities (Figure 1 and Table 2). Therefore, the results reveal that patients who are more physically active preoperatively may acquire more successful objective and functional outcomes. This finding indicates that the surgeon may predict the patientderived outcome through comprehending the subject's preoperative functional level. In the present study, there were no correlations related to the preoperative and postoperative satisfaction scores (Table 2). This result shows that the patient satisfaction may be affected by the other elements such as the character of an individual patient. Several studies have reported the relationship between patientderived outcomes and objective outcomes [12,17]. However, there are no data describing the relationship among each category of patientderived outcomes, including satisfaction and expectation. In the present study, there were significant correlations in all categories of postoperative scores (Figure 2). For example, more functionally active patients may feel less pain and be more satisfied after TKA. Patient-derived scores of the 2011 KSS consist of subscales, which interact with one another. The present study had several limitations: small sample size, omission of mental status as a factor affecting patient satisfaction, and short follow-up period. The study was conducted with a small patient population, indicating that future studies should include a larger sample size. Mental health was not evaluated when assessing patient satisfaction, despite it being an important factor [11,18]. A previous study has reported that the presence of psychological distress is associated with worse outcomes for function and quality of life in patients undergoing TKA [20]. Prospective studies should evaluate the relationship between the 2011 KSS and mental health. Lastly, the mid-term and long-term postoperative outcomes could not be evaluated using the 2011 KSS, as the scoring system is still relatively new. Therefore, a longer follow-up period should be incorporated in prospective studies. 5. Conclusions Patient-derived scores before and after TKA were evaluated using the 2011 KSS. All patient-derived scores except for patient expectation significantly improved postoperatively. The preoperative functional activities score was positively correlated with the postoperative symptoms, functional activities, and objective knee indicators score. All the
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categories of the 2011 KSS were correlated mutually at the short-term postoperative period. Conflict of interest No funding or external support was received by any of the authors in support of or in any relationship to the study. The authors have no conflict of interest. References [1] Becker R, Doring C, Denecke A, Brosz M. Expectation, satisfaction and clinical outcome of patients after total knee arthroplasty. Knee Surg Sports Traumatol Arthrosc 2011;19:1433–41. [2] Bellamy N, Buchanan WW, Goldsmith CH, Campbell J, Stitt LW. Validation study of WOMAC: a health status instrument for measuring clinically important patient relevant outcomes to antirheumatic drug therapy in patients with osteoarthritis of the hip or knee. J Rheumatol 1988;15:1833–40. [3] Bourne RB, Chesworth BM, Davis AM, Mahomed NN, Charron KD. Patient satisfaction after total knee arthroplasty: who is satisfied and who is not? Clin Orthop Relat Res 2010;468:57–63. [4] Bullens PH, van Loon CJ, de Waal Malefijt MC, Laan RF, Veth RP. Patient satisfaction after total knee arthroplasty: a comparison between subjective and objective outcome assessments. J Arthroplasty 2001;16:740–7. [5] Dinjens RN, Senden R, Heyligers IC, Grimm B. Clinimetric quality of the new 2011 Knee Society Score: high validity, low completion rate. Knee 2014;21:647–54. [6] Insall JN, Dorr LD, Scott RD, Scott WN. Rationale of the Knee Society clinical rating system. Clin Orthop Relat Res 1989;13-14. [7] Ishida K, Matsumoto T, Tsumura N, Kubo S, Kitagawa A, Chin T, et al. Mid-term outcomes of computer-assisted total knee arthroplasty. Knee Surg Sports Traumatol Arthrosc 2011;19:1107–12. [8] Kawahara S, Okazaki K, Matsuda S, Nakahara H, Okamoto S, Iwamoto Y. Internal rotation of femoral component affects functional activities after TKA-survey with the 2011 Knee Society Score. J Arthroplasty 2014;29:2319–23. [9] Kurtz SM, Lau E, Ong K, Zhao K, Kelly M, Bozic KJ. Future young patient demand for primary and revision joint replacement: national projections from 2010 to 2030. Clin Orthop Relat Res 2009;467:2606–12. [10] Kwon SK, Kang YG, Kim SJ, Chang CB, Seong SC, Kim TK. Correlations between commonly used clinical outcome scales and patient satisfaction after total knee arthroplasty. J Arthroplasty 2010;25:1125–30. [11] Lopez-Olivo MA, Landon GC, Siff SJ, Edelstein D, Pak C, Kallen MA, et al. Psychosocial determinants of outcomes in knee replacement. Ann Rheum Dis 2011;70:1775–81. [12] Matsuda S, Kawahara S, Okazaki K, Tashiro Y, Iwamoto Y. Postoperative alignment and ROM affect patient satisfaction after TKA. Clin Orthop Relat Res 2013;471: 127–33. [13] Matsumoto T, Tsumura N, Kurosaka M, Muratsu H, Yoshiya S, Kuroda R. Clinical values in computer-assisted total knee arthroplasty. Orthopedics 2006;29:1115–20. [14] Mizner RL, Petterson SC, Clements KE, Zeni Jr JA, Irrgang JJ, Snyder-Mackler L. Measuring functional improvement after total knee arthroplasty requires both performance-based and patient-report assessments: a longitudinal analysis of outcomes. J Arthroplasty 2011;26:728–37. [15] Nakano N, Matsumoto T, Ishida K, Tsumura N, Kuroda R, Kurosaka M. Long-term subjective outcomes of computer-assisted total knee arthroplasty. Int Orthop 2013;37:1911–5. [16] Noble PC, Scuderi GR, Brekke AC, Sikorskii A, Benjamin JB, Lonner JH, et al. Development of a new Knee Society scoring system. Clin Orthop Relat Res 2012;470:20–32. [17] Sasaki E, Tsuda E, Yamamoto Y, Meada S, Otsuka H, Ishibashi Y. Relationship between patient-based outcome score and conventional objective outcome scales in post-operative total knee arthroplasty patients. Int Orthop 2014;38:373–8. [18] Scott CE, Howie CR, MacDonald D, Biant LC. Predicting dissatisfaction following total knee replacement: a prospective study of 1217 patients. J Bone Joint Surg Br 2010; 92:1253–8. [19] Scuderi GR, Bourne RB, Noble PC, Benjamin JB, Lonner JH, Scott WN. The new Knee Society Knee Scoring System. Clin Orthop Relat Res 2012;470:3–19. [20] Utrillas-Compaired A, De la Torre-Escuredo BJ, Tebar-Martinez AJ, Asunsolo-Del BA. Does preoperative psychologic distress influence pain, function, and quality of life after TKA? Clin Orthop Relat Res 2014;472:2457–65.
Contents lists available at ScienceDirect
The Knee
Subjective evaluation before and after total knee arthroplasty using the 2011 Knee Society Score Yuichi Kuroda a, Tomoyuki Matsumoto a,⁎, Koji Takayama a, Kazunari Ishida b, Ryosuke Kuroda a, Masahiro Kurosaka a a b
Department of Orthopaedic Surgery, Kobe University Graduate School of Medicine, Kobe, Japan Department of Orthopaedic Surgery, Kobe Kaisei Hospital, Kobe, Japan
a r t i c l e
i n f o
Article history: Received 14 November 2015 Received in revised form 26 May 2016 Accepted 16 June 2016 Keywords: Total knee arthroplasty The 2011 Knee Society Knee Scoring System Subjective outcome Patient satisfaction Patient expectation
a b s t r a c t Background: Patient satisfaction has been recognized as an important evaluation of total knee arthroplasty (TKA). Therefore, the 2011 Knee Society Knee Scoring System (2011 KSS) was developed in order to quantify patient satisfaction, expectations, and physical activities following TKA. However, very few reports have described subjective evaluation before TKA using the 2011 KSS, as the scoring system is still relatively new. Therefore, the degree of improvement and change over time after TKA has not been evaluated. Methods: Forty-nine consecutive patients (79 knees) with a mean age of 74.8 ± 7.3 years were prospectively included in the study and evaluated preoperatively and one year postoperatively. The following questions were assessed using the 2011 KSS: (1) Do patient-derived clinical scores improve after TKA? (2) Do patientderived clinical scores before TKA correlate with those after TKA? and (3) Are there correlations among each category of the 2011 KSS score? Results: The majority of categories showed significant improvements after TKA. The preoperative functional activities score was positively correlated with the postoperative symptoms, functional activities, and objective score. Each category of the 2011 KSS score correlated with others postoperatively. Conclusions: All patient-derived scores except for patient expectation significantly improved postoperatively. The more functionally active patients before receiving TKA acquired more successful objective and functional outcomes, and the postoperative knee condition was directly influenced by each subscale of the 2011 KSS. © 2016 Elsevier B.V. All rights reserved.
1. Introduction Total knee arthroplasty (TKA) is a well-established surgical procedure that generally results in pain relief, improved physical function, and high level of patient satisfaction. Beneficial results are achieved in most patients after TKA, and advanced surgical techniques and prosthesis design have led to improved outcomes [7,13]. Although the benefits of TKA from the physician's viewpoint, such as range of motion (ROM) and radiographic outcomes, have previously been studied [7,13], the benefits of the procedure from the patient's point of view are currently unknown. Patient satisfaction has been recognized as an important basis of evaluation in TKA [1,3,10], but it is very difficult to quantify and evaluate patient satisfaction and subjective knee function after TKA. In comparison, physician-derived scores can be quantified with ease, but these are poorly related to patient-reported scores [4]. As ⁎ Corresponding author at: Department of Orthopaedic Surgery, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan. Tel.: +81 78 382 5985; fax: +81 78 351 6944. E-mail address: [email protected] (T. Matsumoto).
http://dx.doi.org/10.1016/j.knee.2016.06.008 0968-0160/© 2016 Elsevier B.V. All rights reserved.
a result, patient-derived outcome scales have become increasingly important [14]. Previously, the visual analog scale (VAS) and Western Ontario and McMasters Universities Osteoarthritis Index (WOMAC) have been used to evaluate patient satisfaction and subjective knee function [2], despite these instruments not being scoring systems to specifically measure patient satisfaction and knee function after TKA [4]. In 2012, the Knee Society developed a new Knee Society knee scoring system – The 2011 Knee Society Knee Scoring System (2011 KSS) – in order to quantify patient satisfaction, expectations, and physical activities following TKA [16,19]. However, the literature on the use of the 2011 KSS in evaluating patients' subjective outcomes after TKA is limited due to its novel nature [8,12,15,5]. Furthermore, very few reports have described subjective evaluation before TKA using the 2011 KSS [5], and the degree of improvement and change over time after TKA have not been evaluated. Therefore, in this study, the following questions were assessed using the 2011 KSS: (1) Do patient-derived clinical scores improve after TKA? (2) Do patient-derived clinical scores before TKA correlate with those after TKA? and (3) Are there correlations among each of the following
Y. Kuroda et al. / The Knee 23 (2016) 964–967 Table 1 Comparisons of preoperative and postoperative scores. The 2011 KSS categories
Pre-operation
Post-operation
P
Objective knee indicators Symptoms Satisfaction Expectations Functional activities
67.7 ± 12.6 8.6 ± 5.4 15.3 ± 7.9 12.3 ± 2.5 43.0 ± 18.6
92.3 ± 5.5 18.8 ± 4.5 25.6 ± 7.3 11.0 ± 2.7 65.8 ± 19.0
b0.001 b0.001 b0.001 b0.001 b0.001
The data are expressed as mean ± SD values.
categories of the 2011 KSS score when administered postoperatively: symptoms, patient satisfaction, patient expectations, and functional activities? 2. Materials and methods From May 2012 to December 2013, 75 consecutive patients (79 knees) who had undergone TKA (32 knees: P.F.C. Sigma, DePuy Orthopaedics, Inc., Warsaw, IN; 47 knees: e-motion, Aesculap Inc., Center Valley, PA) were prospectively enrolled in the study. The patient cohort consisted of 63 female and 12 male subjects with a mean age of 74.8 ± 7.3 years (mean ± standard deviation). Posterior-stabilizing prostheses and cruciate-retaining implants were used in 54 knees and 25 knees, respectively. Seventy-two knees had a diagnosis of osteoarthritis, two knees had a diagnosis of osteonecrosis, and five knees had a diagnosis of rheumatoid arthritis. Patients with bone defects requiring bone grafting or augmentation, revision arthroplasties, and those who underwent an alternative surgical procedure during the study were excluded. The patient-derived score of the 2011 KSS has the following four categories: symptoms, patient satisfaction, patient expectations, and functional activities (e.g., walking/standing, standard activities, advanced activities, and discretionary activities). The objective knee indicators score of the 2011 KSS, completed by the surgeon,
965
includes alignment, instability, and joint motion. The 2011 KSS, which incorporates both the preoperative and postoperative versions, shows that the only difference between the two versions is the patient expectations category [16,19]. The 2011 KSS questionnaires were completed on admission for TKA and at a one-year outpatient appointment following TKA. An institutional review board approved the survey. Patients provided informed consent prior to participating in the study and no patients were excluded after informed consent. The 2011 KSS scores, including preoperative objective knee indicators, were compared with those at one year postoperatively, and the correlations between the preoperative and postoperative scores in each category were evaluated. Furthermore, the correlations among each category of the 2011 KSS score were evaluated one year after TKA. Statview 5.0 (Abacus Concepts Inc., Berkeley, CA, USA) was used for statistical analysis. The differences between preoperative and postoperative scores were analyzed using paired Student's t-tests. Pearson correlation coefficient tests were used to examine the correlations of the 2011 KSS scores; differences with P b 0.05 were considered statistically significant. 3. Results 3.1. Comparisons of preoperative and postoperative scores All categories, except for the patient expectation score of the 2011 KSS, showed significant improvements after TKA (P b 0.001) (Table 1). The postoperative patient expectation score was significantly lower than the preoperative score (P b 0.001) (Table 1). 3.2. Correlations between preoperative and postoperative scores The preoperative functional activities score was positively correlated with the postoperative symptoms, the functional activities, and the objective knee indicators score (Figure 1 and Table 2). The preoperative expectations score was positively correlated with the postoperative symptoms, functional activities and the objective knee indicators score. There were no correlations related to the preoperative and postoperative satisfaction scores (Table 2).
Figure 1. The relationships between preoperative functional activities score and each of postoperative functional activities, symptoms, and functional activities score of the 2011 Knee Society Scoring System.
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Y. Kuroda et al. / The Knee 23 (2016) 964–967
Table 2 Correlations of preoperative and postoperative scores. Post-operation Pre operation
Objective knee indicators
Symptoms
Satisfaction
Expectations
Functional activities
Objective knee indicators Symptoms Satisfaction Expectations Functional activities
0.07 (0.540) 0.08 (0.501) 0.07 (0.553) 0.27⁎ (0.018) 0.32⁎ (0.004)
−0.08 (0.490) 0.06 (0.597) 0.10 (0.386) 0.27⁎ (0.016) 0.26⁎ (0.021)
0.10 (0.399) 0.15 (0.181) 0.12 (0.274) 0.17 (0.127) 0.14 (0.216)
0.14 (0.227) 0.07 (0.541) −0.08 (0.470) 0.14 (0.204) 0.22 (0.056)
0.17 (0.126) 0.08 (0.495) −0.05 (0.662) 0.23⁎ (0.038) 0.46⁎ (b0.001)
The data are expressed as r-value (P-value) by Pearson's correlations. ⁎ P b 0.05.
3.3. Correlations among each category of postoperative score There were significant correlations in all the categories of postoperative scores (r-range 0.42–0.58) (Figure 2).
4. Discussion The preoperative and postoperative patient-derived scores of patients who underwent TKA using the 2011 KSS were investigated. The most significant findings were that all patient-derived scores except for patient expectation significantly improved postoperatively, and the preoperative functional activities score was positively correlated with postoperative symptoms, functional activities, and objective knee indicators scores. Furthermore, all the categories of the 2011 KSS correlated mutually at the one-year follow-up appointment. The proportion of younger and more physically active patients who undergo TKA has increased in recent times [9]. In order to accommodate these changes, the 2011 KSS was developed from the conventional Knee
Society scoring system (1989), but only included three subjective items: pain, walking ability, and ability to climb stairs [6] to better characterize the expectation, satisfaction, and physical activities of patients who underwent TKA. The 2011 KSS was reported to be a reliable, internally consistent, and responsive questionnaire with construct validity when used to assess the outcomes of TKA patients [5]. Matsuda et al. reported that surgeons who performed TKA overestimated symptoms and function, and there was a weak relationship between patient-derived and physician-derived scores on postoperative pain and function using this scoring system [12]. Although previous studies have reported relatively low scores of each category of the 2011 KSS for patients who underwent TKA, these studies did not evaluate preoperative patient-derived scores [12,15]. Therefore, the degree of improvement and change over time after TKA is unknown. In the present study, all patient-derived scores except for patient expectation significantly improved postoperatively, indicating that patients may be satisfied after TKA in an alternative way compared with preoperative expectations. Patient expectation scores may appear
Figure 2. The relationships among each category of postoperative the 2011 Knee Society scores.
Y. Kuroda et al. / The Knee 23 (2016) 964–967
to worsen postoperatively, due to a difference in the contents of questionnaires used preoperatively and postoperatively. The preoperative version includes the expectations of postoperative outcomes, whereas the postoperative version refers to superiority or inferiority between the knee condition expected preoperatively and postoperatively. Furthermore, the relationship between patients and surgeons, including the content of informed consent, may affect the expectation score more than the other categories. An inadequate explanation of the operation, including operative procedure, complications, and postoperative rehabilitation, may lead the patients to have disappointing results. A previous study reported that limited postoperative range of motion (ROM) was negatively correlated with postoperative functional activities [12]. However, the present study found that the postoperative objective indicator was positively correlated with preoperative functional activities, which in turn were positively correlated with the postoperative functional activities (Figure 1 and Table 2). Therefore, the results reveal that patients who are more physically active preoperatively may acquire more successful objective and functional outcomes. This finding indicates that the surgeon may predict the patientderived outcome through comprehending the subject's preoperative functional level. In the present study, there were no correlations related to the preoperative and postoperative satisfaction scores (Table 2). This result shows that the patient satisfaction may be affected by the other elements such as the character of an individual patient. Several studies have reported the relationship between patientderived outcomes and objective outcomes [12,17]. However, there are no data describing the relationship among each category of patientderived outcomes, including satisfaction and expectation. In the present study, there were significant correlations in all categories of postoperative scores (Figure 2). For example, more functionally active patients may feel less pain and be more satisfied after TKA. Patient-derived scores of the 2011 KSS consist of subscales, which interact with one another. The present study had several limitations: small sample size, omission of mental status as a factor affecting patient satisfaction, and short follow-up period. The study was conducted with a small patient population, indicating that future studies should include a larger sample size. Mental health was not evaluated when assessing patient satisfaction, despite it being an important factor [11,18]. A previous study has reported that the presence of psychological distress is associated with worse outcomes for function and quality of life in patients undergoing TKA [20]. Prospective studies should evaluate the relationship between the 2011 KSS and mental health. Lastly, the mid-term and long-term postoperative outcomes could not be evaluated using the 2011 KSS, as the scoring system is still relatively new. Therefore, a longer follow-up period should be incorporated in prospective studies. 5. Conclusions Patient-derived scores before and after TKA were evaluated using the 2011 KSS. All patient-derived scores except for patient expectation significantly improved postoperatively. The preoperative functional activities score was positively correlated with the postoperative symptoms, functional activities, and objective knee indicators score. All the
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categories of the 2011 KSS were correlated mutually at the short-term postoperative period. Conflict of interest No funding or external support was received by any of the authors in support of or in any relationship to the study. The authors have no conflict of interest. References [1] Becker R, Doring C, Denecke A, Brosz M. Expectation, satisfaction and clinical outcome of patients after total knee arthroplasty. Knee Surg Sports Traumatol Arthrosc 2011;19:1433–41. [2] Bellamy N, Buchanan WW, Goldsmith CH, Campbell J, Stitt LW. Validation study of WOMAC: a health status instrument for measuring clinically important patient relevant outcomes to antirheumatic drug therapy in patients with osteoarthritis of the hip or knee. J Rheumatol 1988;15:1833–40. [3] Bourne RB, Chesworth BM, Davis AM, Mahomed NN, Charron KD. Patient satisfaction after total knee arthroplasty: who is satisfied and who is not? Clin Orthop Relat Res 2010;468:57–63. [4] Bullens PH, van Loon CJ, de Waal Malefijt MC, Laan RF, Veth RP. Patient satisfaction after total knee arthroplasty: a comparison between subjective and objective outcome assessments. J Arthroplasty 2001;16:740–7. [5] Dinjens RN, Senden R, Heyligers IC, Grimm B. Clinimetric quality of the new 2011 Knee Society Score: high validity, low completion rate. Knee 2014;21:647–54. [6] Insall JN, Dorr LD, Scott RD, Scott WN. Rationale of the Knee Society clinical rating system. Clin Orthop Relat Res 1989;13-14. [7] Ishida K, Matsumoto T, Tsumura N, Kubo S, Kitagawa A, Chin T, et al. Mid-term outcomes of computer-assisted total knee arthroplasty. Knee Surg Sports Traumatol Arthrosc 2011;19:1107–12. [8] Kawahara S, Okazaki K, Matsuda S, Nakahara H, Okamoto S, Iwamoto Y. Internal rotation of femoral component affects functional activities after TKA-survey with the 2011 Knee Society Score. J Arthroplasty 2014;29:2319–23. [9] Kurtz SM, Lau E, Ong K, Zhao K, Kelly M, Bozic KJ. Future young patient demand for primary and revision joint replacement: national projections from 2010 to 2030. Clin Orthop Relat Res 2009;467:2606–12. [10] Kwon SK, Kang YG, Kim SJ, Chang CB, Seong SC, Kim TK. Correlations between commonly used clinical outcome scales and patient satisfaction after total knee arthroplasty. J Arthroplasty 2010;25:1125–30. [11] Lopez-Olivo MA, Landon GC, Siff SJ, Edelstein D, Pak C, Kallen MA, et al. Psychosocial determinants of outcomes in knee replacement. Ann Rheum Dis 2011;70:1775–81. [12] Matsuda S, Kawahara S, Okazaki K, Tashiro Y, Iwamoto Y. Postoperative alignment and ROM affect patient satisfaction after TKA. Clin Orthop Relat Res 2013;471: 127–33. [13] Matsumoto T, Tsumura N, Kurosaka M, Muratsu H, Yoshiya S, Kuroda R. Clinical values in computer-assisted total knee arthroplasty. Orthopedics 2006;29:1115–20. [14] Mizner RL, Petterson SC, Clements KE, Zeni Jr JA, Irrgang JJ, Snyder-Mackler L. Measuring functional improvement after total knee arthroplasty requires both performance-based and patient-report assessments: a longitudinal analysis of outcomes. J Arthroplasty 2011;26:728–37. [15] Nakano N, Matsumoto T, Ishida K, Tsumura N, Kuroda R, Kurosaka M. Long-term subjective outcomes of computer-assisted total knee arthroplasty. Int Orthop 2013;37:1911–5. [16] Noble PC, Scuderi GR, Brekke AC, Sikorskii A, Benjamin JB, Lonner JH, et al. Development of a new Knee Society scoring system. Clin Orthop Relat Res 2012;470:20–32. [17] Sasaki E, Tsuda E, Yamamoto Y, Meada S, Otsuka H, Ishibashi Y. Relationship between patient-based outcome score and conventional objective outcome scales in post-operative total knee arthroplasty patients. Int Orthop 2014;38:373–8. [18] Scott CE, Howie CR, MacDonald D, Biant LC. Predicting dissatisfaction following total knee replacement: a prospective study of 1217 patients. J Bone Joint Surg Br 2010; 92:1253–8. [19] Scuderi GR, Bourne RB, Noble PC, Benjamin JB, Lonner JH, Scott WN. The new Knee Society Knee Scoring System. Clin Orthop Relat Res 2012;470:3–19. [20] Utrillas-Compaired A, De la Torre-Escuredo BJ, Tebar-Martinez AJ, Asunsolo-Del BA. Does preoperative psychologic distress influence pain, function, and quality of life after TKA? Clin Orthop Relat Res 2014;472:2457–65.