Intermediate-Term Comparison of Posterior Cruciate-Retaining Versus Posterior-Stabilized Total Knee Arthroplasty Using the New Knee Scoring System

Transcription

1 Intermediate-Term Comparison of Posterior Cruciate-Retaining Versus Posterior-Stabilized Total Knee Arthroplasty Using the New Knee Scoring System Yohei Kawakami, MD, PhD; Tomoyuki Matsumoto, MD, PhD; Koji Takayama, MD, PhD; Kazunari Ishida, MD, PhD; Naoki Nakano, MD; Takehiko Matsushita, MD, PhD; Yuichi Kuroda, MD; Kunji Patel, MD; Ryosuke Kuroda, MD, PhD; Masahiro Kurosaka, MD, PhD abstract With the dramatic shift in the proportion of younger and more active patients undergoing total knee arthroplasty (TKA), the difference in patient-reported outcomes between cruciate-retaining and posterior-stabilized prostheses will become very important. The goal of this study was to clarify and compare the intermediate-term results of cruciateretaining and posterior-stabilized TKAs with new patient-derived scores. This study included 60 patients who underwent TKA because of varus-type osteoarthritis (30 patients in the cruciate-retaining group and 30 patients in the posterior-stabilized group) an average of 8 years earlier. The authors investigated patient-reported outcomes using the Knee Society s new scoring system, which was adapted to the diverse lifestyles and activities of contemporary patients undergoing TKA. The results of 48 patients (23 patients in the cruciate-retaining group and 25 patients in the posterior-stabilized group) were assessed. The questionnaire included 7 sections: symptoms, patient satisfaction, patient expectation, walking/standing, standard activities, advanced activities, and discretionary activities. For patient satisfaction, the score of the cruciate-retaining group was slightly but not significantly higher than that of the posterior-stabilized group. No significant difference in score was seen between the cruciate-retaining group and the posterior-stabilized group for any other sections. In addition, no statistically significant difference was seen in range of motion or radiographic alignment postoperatively. After intermediate-term follow-up, the authors found no statistically significant difference in clinical outcomes between patients undergoing cruciate-retaining TKA and those undergoing posterior-stabilized TKA. Additional studies are needed to corroborate and validate these results. [Orthopedics. 2015; 38(12):e1127-e1132.] The authors are from the Department of Orthopaedic Surgery (YKawakami, TMatsumoto, KT, NN, TMatsushita, YKuroda, RK, MK), Kobe University Graduate School of Medicine, and the Department of Orthopaedic Surgery (KI), Kobe Kaisei Hospital, Kobe, Hyogo, Japan; and the Department of Orthopaedic Surgery (KP), University of Pittsburgh, Pittsburgh, Pennsylvania. The authors have no relevant financial relationships to disclose. Correspondence should be addressed to: Tomoyuki Matsumoto, MD, PhD, Department of Orthopaedic Surgery, Kobe University Graduate School of Medicine, Kusunoki-Cho, Chuo-Ku, Kobe , Japan (matsun@m4.dion.ne.jp). Received: February 2, 2015; Accepted: April 20, doi: / DECEMBER 2015 Volume 38 Number 12 e1127

2 Total knee arthroplasty (TKA) is a well-established surgical procedure for improving physical function and relieving pain in patients with severe osteoarthritis or rheumatoid arthritis. Excellent results are achieved in most patients after TKA because of improved outcomes from modern prosthesis design and advances in surgical techniques. This has largely remained true, even in the face of multiple surgical approaches, a dizzying array of implant choices, and a multitude of perioperative care regimens. 1,2 An ongoing debate about TKA is how to manage the posterior cruciate ligament, which is believed to be the primary stabilizer of the knee. 3 Both posterior cruciateretaining and posterior-stabilized TKAs have shown long-term pain relief and improved function. 4-6 Nevertheless, controversy continues regarding which design is superior. Proponents of cruciate-retaining designs believe that maintaining the posterior cruciate ligament provides increased stability and promotes femoral rollback, which enhances stair-climbing ability Further, the maintained posterior cruciate ligament can absorb shear forces that otherwise would be transmitted to the bone implant interface and could result in premature loosening. 9 Conversely, proponents of posterior-stabilized designs argue that substituting the posterior cruciate ligament with a post and cam improves range of motion as a result of mechanical reinforcement of femoral rollback. 11,12 Posterior translation of the femur creates more clearance over the tibia and theoretically more flexion. 13 Previous reports compared the kinematic pattern of soft tissue balance between cruciate-retaining and posteriorstabilized TKAs and showed that the use of an offset-type tensor to intraoperatively measure soft tissue balance for cruciateretaining and posterior-stabilized TKAs allows postoperative tissue balance to be predicted, even after 5 years, as assessed by stress radiographs However, these studies showed no significant differences in clinical outcomes between cruciateretaining and posterior-stabilized TKAs at the minimum 5-year follow up, including measures such as the Knee Society Score, range of motion, extension, and flexion angle. In the debate over which type of prosthesis is better, various measures, such as range of motion and radiographic findings, are used to inform the physician s viewpoint. However, the difference between the 2 types of prostheses from the patient s viewpoint based on measures of patient satisfaction have not been well examined, despite the recognition of patient satisfaction as an important factor in the evaluation of TKA This may be because patient satisfaction and subjective knee function are difficult to quantify; furthermore, there may be a poor correlation between physician-based scores and patient-reported scores. 20,21 The Knee Society clinical rating system, first published in 1989, had only 3 patientreported sections (pain, walking ability, and ability to climb stairs) and has been widely adopted as an objective measure of knee status in patients undergoing TKA. 22 However, some have challenged its reliability and responsiveness. Additionally, with the dramatic shift in the proportion of younger and more active patients undergoing TKA, the outcome of TKA must address the ability of each patient to remain actively involved in functional and recreational activities far beyond the rudimentary activities of daily life. 23 Thus, patient-reported outcome scales that characterize the expectations, satisfaction, and physical activities of younger, more diverse populations of patients undergoing TKA are gaining increased recognition. 24 In 2012, the Knee Society created a new scoring system, the new Knee Society Knee Scoring System (new KSKSS), to quantify the expectations, satisfaction, and physical activities of patients who undergo TKA. 25,26 The new KSKSS derives from both physician and patient reports and is adapted to the diverse lifestyles and activities of contemporary patients who undergo TKA. The goal of this study was to investigate the long-term clinical outcomes of cruciate-retaining and posterior-stabilized TKAs after an average of 8 years by using patient-reported clinical results. The authors postulated that objective differences in kinematic patterns of soft tissue balance between posterior-stabilized and cruciate-retaining TKAs may influence the subjective clinical outcomes measured by the new KSKSS at 8 years. Materials and Methods The study protocol was approved by the authors hospital ethics committee, and all patients provided informed consent for participation. The inclusion criteria consisted of substantial pain and loss of function as a result of osteoarthritis of the knee. To fairly assess patient outcomes and minimize the effects of clinical variables, the exclusion criteria consisted of patients with valgus deformity, severe bony defect requiring bone graft or augmentation, revision total knee arthroplasty, active knee joint infection, and rheumatoid arthritis. From a group of 60 consecutive Japanese patients who met the study criteria and were blinded to the type of implant received, the authors prospectively randomized 30 patients (30 knees) to receive a cruciate-retaining TKA (NexGen CR- Flex; Zimmer, Inc, Warsaw, Indiana) and the other 30 patients (30 knees) to receive a posterior-stabilized TKA (NexGen LPS- Flex; Zimmer, Inc), according to the envelope method, between 2003 and Each surgery was performed by the same senior author (T. Matsumoto). At an average of 8 years after surgery, the selected 60 patients (30 patients in each group) were mailed the new KSKSS questionnaire that had been translated directly into Japanese, and data were analyzed retrospectively. The new KSKSS consists of 7 patientreported sections: symptoms, patient satisfaction, patient expectation, walking/ standing, standard activities, advanced ace1128 Copyright SLACK Incorporated

3 tivities, and discretionary activities. Total numbers of points in each section are 25, 40, 15, 30, 30, 25, and 15, respectively. At an average of 8 years of follow-up, 7 patients in the cruciate-retaining group and 5 patients in the posterior-stabilized group were excluded because of death, loss to follow-up, or inability to contact. The remaining 48 patients (23 in the cruciate-retaining group and 25 in the posterior-stabilized group) were included in the study group (Table 1). Patients in the cruciate-retaining group had a mean age of 73.7±6.1 years, whereas those in the posterior-stabilized group had a mean age of 74.8±9.2 years, with no significant difference between groups. For patients who completed the questionnaire correctly, the authors also reviewed the medical records, including objective data collected preoperatively as well as 6 years postoperatively. The details of the method for collecting objective data were reported earlier. 27 In brief, for radiologic measurements, weight-bearing radiographs (320-mA, 0.03-s exposure at kv, depending on soft tissue thickness) using the anteroposterior long leg view were obtained and evaluated to measure the coronal mechanical axis of the femur and tibia both preoperatively and 6 years postoperatively. Range of motion was also evaluated and recorded by an independent observer preoperatively and 8 years postoperatively. In addition, knee crepitus and other patellofemoral articulation complications, such as subluxation, dislocation of the extensor mechanism, patellar fracture, and need for revision surgery, were recorded. Characteristic Surgical Procedure The surgical techniques used for each group were previously reported. 14 In brief, all TKAs were performed with the measured resection technique with a conventional resection block. The air tourniquet was inflated with 280 mm Hg at the outset of each procedure, and the authors performed a medial parapatellar arthrotomy. In the 30 patients who were randomized to undergo cruciate-retaining TKA, the authors resected the anterior cruciate ligament and preserved the posterior cruciate ligament along with its bony island. In the 30 patients who were randomized to undergo posterior-stabilized TKA, the anterior cruciate ligament and posterior cruciate ligament were both resected. A distal femoral osteotomy perpendicular to the mechanical axis of the femur was performed, with preoperative long leg radiographs. Femoral external rotation was preset at 3 relative to the posterior condylar axis in all patients. Then a proximal tibial osteotomy was performed and was aimed for cuts perpendicular to the long axis in the coronal plane and at a posterior inclination of 7 in the sagittal plane. No bony defects were noted along the eroded medial tibial plateau in these cases. After each osteotomy, the authors removed osteophytes, released the posterior capsule along the femur, and corrected any ligament imbalances that occurred in the coronal plane by appropriately releasing soft tissue along the medial structures of the knee. Each osteotomy and soft tissue release was performed with a spacer block. Statistical Analysis The results were analyzed with Graph- Pad PRISM version 6 statistical software (GraphPad Software, Inc, La Jolla, California). All values were expressed as Table 1 Demographic Data for the Cruciate-Retaining and Posterior-Stabilized Groups Cruciate-Retaining Group (n=23) Posterior-Stabilized Group (n=25) Sex, No. (% male) 3 (13) 5 (20).703 Age at operation, mean±sd, y 73.7± ± Height, mean±sd, cm 148.7± ± Weight, mean±sd, kg 56.1± ± Follow-up period, mean±sd, mo 95.4± ± mean±sd. The authors performed an unpaired Student s t test for comparisons between the cruciate-retaining and posteriorstabilized groups. P<.05 was considered to denote statistical significance. Based on the previous pilot study, the authors determined that 26 patients in each group would be required to detect a difference between the 2 groups, as calculated with G*Power version 3.1 ( with ß=0.2, a=0.05, and median effect size set at Results No statistically significant difference was found between the 2 groups in sex, age, height, weight, or duration of follow-up (Table 1). Because few patients regularly visited the office years after the procedure, the authors did not obtain current objective information, such as radiographic data, range of motion, and joint instability. No patients were recalled for this study; all data were obtained from the questionnaires. Mean duration of follow-up was 95.4 months in the cruciate-retaining group and months in the posterior-stabilized group. The results of the questionnaire showed no statistically significant differences between the 2 groups for any of the 7 sections of the new KSKSS (symptoms, patient satisfaction, patient expectation, walking/standing, standard P DECEMBER 2015 Volume 38 Number 12 e1129

4 Table 2 Subjective Scores in the New Knee Society Knee Scoring System for the Cruciate-Retaining and Posterior-Stabilized Groups New Knee Society Knee Scoring System Section (Total No. of Points) Cruciate-Retaining Group Score, Mean±SD Posterior-Stabilized Group Symptoms (25) 20.1± ± Patient satisfaction (40) 29.6± ± Patient expectation (15) 11.8± ± Walking/standing (30) 19.5± ± Standard activities (25) 24.9± ± Advanced activities (25) 13.4± ± Discretionary activities (15) 10.9± ± Table 3 Comparison of Range of Motion and the Coronal Mechanical Axis Measurement Cruciate- Retaining Group Mean±SD Posterior- Stabilized Group Preoperative range of motion ± ± Postoperative range of motion ± ± Preoperative extension -7.4 ± ± Postoperative extension -0.9 ± ± Preoperative flexion ± ± Postoperative flexion ± ± Preoperative coronal mechanical axis a 9.9 ± ± Postoperative coronal mechanical axis a -1.2 ± ± a Positive values indicate varus alignment, and negative values indicate valgus alignment. activities, advanced activities, and discretionary activities). In the category of patient satisfaction, the score for the cruciate-retaining group was slightly but not significantly higher than that for the posterior-stabilized group. Details are shown in Table 2. The current study showed no significant differences in range of motion, extension, or flexion between the 2 groups either preoperatively or postoperatively (Table 3). All patients were free of patellofemoral symptoms, including patellar clunk syndrome, patellar subluxation, and fracture. Knee crepitus was noted in 1 patient in the cruciate-retaining group and 3 patients in the posterior-stabilized group, but none of the patients had knee pain. Radiographic evaluation showed that the coronal axis between the 2 groups was almost the same preoperatively and postoperatively. Discussion The current study showed that the subjective outcomes of patients who underwent cruciate-retaining TKA and those P P of patients who underwent posteriorstabilized TKA were not significantly different, even 8 years after surgery. With respect to clinical outcomes, the superiority of either cruciate-retaining TKA or posterior-stabilized TKA remains a source of great controversy. 29 Proponents of cruciate-retaining TKA advocate maintaining the posterior cruciate ligament to increase stability, promote femoral rollback, and enhance the patient s ability to climb stairs. 9,10 Proponents of posteriorstabilized TKA highlight studies in which patients with a resected posterior cruciate ligament have greater postoperative range of motion. 10,30,31 Previous meta-analysis showed a statistically significant trend toward greater flexion and range of motion in patients with posterior-stabilized TKA. 4,6 However, the advantage is not great, and studies have not shown a difference in clinical outcomes between the 2 types of knees. 4,6,32 Moreover, in studies of bilateral TKA in which patients had cruciate-retaining TKA on one side and posterior-stabilized TKA on the other, no significant difference was found in patient-derived parameters, such as pain, satisfaction with the result, and feel of the knee, between the cruciate-retaining and posterior-stabilized TKAs. 33 The current study also found no significant differences in clinical outcomes between the 2 groups, including the new KSKSS, range of motion, extension, and flexion angle. Furthermore, differences in patterns of soft tissue balance between cruciateretaining and posterior-stabilized TKAs, as assessed intraoperatively, also did not affect long-term clinical scores, even with a patient-reported system. Currently, TKA is among the most successful orthopedic procedures available. However, as younger and more active patients with osteoarthritis undergo TKA, their expectations for postoperative activities tend to be higher and their activities more diverse. 34 Additionally, patient satisfaction is often focused on quality of life after TKA. 17,35 A poor correlation has e1130 Copyright SLACK Incorporated

5 been reported between physician-derived and patient-reported outcomes, 20 and physicians tend to predict that the outcomes will be better than they actually are after surgery. 21 The new KSKSS focuses on the expectations, satisfaction, and physical activities of patients who undergo TKA and uses standard statistical and psychometric procedures for validation. 25 Using the new KSKSS questionnaire, Matsuda et al 36 reported that surgeons overestimate improvements in symptoms and function and that there is a weak relationship between patient-derived and physician-derived scores for postoperative pain and function. Kawahara et al 37 reported that postoperative varus alignment and restricted range of motion result in lower patient satisfaction using this score. Nakano et al 38 used this score to show that there are no subjective advantages gained from the use of a navigation system for TKA. In the current study, the cruciate-retaining group scored slightly higher than the posterior-stabilized group in the categories of symptoms and patient satisfaction, but the difference was not statistically significant. These data might reflect the different kinematic pattern of the 2 prostheses. The authors believe that there are several reasons why no difference was found between the 2 groups. First, small sample size may be an important factor. Second, although the new KSKSS is suitable mainly for active or relatively young patients, especially in the assessment of advanced and discretionary activities, most patients in Japan who undergo TKA are older than 70 years. Therefore, significant differences in scores may not be detected in this patient group. There is a growing number of active patients who undergo TKA in the United States, and the authors believe that TKA will be performed in younger patients in Japan in the future. The new KSKSS will become increasingly important as a means to evaluate patients undergoing TKA in Japan. Limitations The authors acknowledge several limitations of this study. The first limitation is the patient population. The number of patients in the current study was too small to assess the relationship between soft tissue balance and clinical outcomes. Larger numbers of patients should be studied in the future, and these studies may lead to different results. Second, the surgeon s experience with each technique may affect the results. If the surgeon performs 1 type of procedure more than the other, this difference may affect the clinical results. To minimize this bias, in the current study, all procedures were performed by the senior author, who has performed almost equal numbers of cruciate-retaining and posterior-stabilized TKAs. Third, the authors did not have objective data available 8 years after surgery. If patients who undergo TKA return to their physicians offices for follow-up more than 8 years after surgery, this would permit physicians to obtain objective findings and compare objective and subjective outcomes. Fourth, patient satisfaction is difficult to evaluate. The authors did not consider other factors, such as other medical complications, bone fractures, other joint disorders, or mental health, all of which may influence patient-reported clinical outcomes. Defining these conditions would help to eliminate their effects. Finally, because the new KSKSS was only introduced in 2012, the authors could not obtain preoperative and short-term patient-reported outcomes, and this limited their ability to compare the degree of improvement and change over time in the 2 patient groups. Conclusion The current study showed no significant differences in outcomes, including the new KSKSS, range of motion, extension, flexion angle, and radiographic alignment, between patients with cruciateretaining and posterior-stabilized TKAs. In the future, a population that includes a larger number of patients and a range of age groups should be evaluated. References 1. Bourne RB, Laskin RS, Guerin JS. Ten-year results of the first 100 Genesis II total knee replacement procedures. Orthopedics. 2007; 30(suppl 8): Attar FG, Khaw FM, Kirk LM, Gregg PJ. Survivorship analysis at 15 years of cemented press-fit condylar total knee arthroplasty. J Arthroplasty. 2008; 23(3): Harner CD, Xerogeanes JW, Livesay GA, et al. The human posterior cruciate ligament complex: an interdisciplinary study. Ligament morphology and biomechanical evaluation. Am J Sports Med. 1995; 23(6): Bercik MJ, Joshi A, Parvizi J. Posterior cruciate-retaining versus posterior-stabilized total knee arthroplasty: a meta-analysis. J Arthroplasty. 2013; 28(3): van den Boom LG, Brouwer RW, van den Akker-Scheek I, Bulstra SK, van Raaij JJ. Retention of the posterior cruciate ligament versus the posterior stabilized design in total knee arthroplasty: a prospective randomized controlled clinical trial. BMC Musculoskelet Disord. 2009; 10: Li N, Tan Y, Deng Y, Chen L. Posterior cruciate-retaining versus posterior stabilized total knee arthroplasty: a meta-analysis of randomized controlled trials. Knee Surg Sports Traumatol Arthrosc. 2014; 22(3): Andriacchi TP, Andersson GB, Fermier RW, Stern D, Galante JO. A study of lower-limb mechanics during stair-climbing. J Bone Joint Surg Am. 1980; 62(5): Andriacchi TP, Galante JO, Fermier RW. The influence of total knee-replacement design on walking and stair-climbing. J Bone Joint Surg Am. 1982; 64(9): Dorr LD, Ochsner JL, Gronley J, Perry J. Functional comparison of posterior cruciateretained versus cruciate-sacrificed total knee arthroplasty. Clin Orthop Relat Res. 1988; 236: Maloney WJ, Schurman DJ. The effects of implant design on range of motion after total knee arthroplasty: total condylar versus posterior stabilized total condylar designs. Clin Orthop Relat Res. 1992; 278: Pagnano MW, Cushner FD, Scott WN. Role of the posterior cruciate ligament in total knee arthroplasty. J Am Acad Orthop Surg. 1998; 6(3): Udomkiat P, Meng BJ, Dorr LD, Wan Z. Functional comparison of posterior cruciate retention and substitution knee replacement. Clin Orthop Relat Res. 2000; 378: Victor J, Banks S, Bellemans J. Kinematics of posterior cruciate ligament-retaining and -substituting total knee arthroplasty: a prospective randomised outcome study. J Bone Joint Surg Br. 2005; 87(5): DECEMBER 2015 Volume 38 Number Matsumoto T, Muratsu H, Kubo S, Matsue1131

6 shita T, Kurosaka M, Kuroda R. Soft tissue tension in cruciate-retaining and posteriorstabilized total knee arthroplasty. J Arthroplasty. 2011; 26(5): Matsumoto T, Kuroda R, Kubo S, Muratsu H, Mizuno K, Kurosaka M. The intra-operative joint gap in cruciate-retaining compared with posterior-stabilised total knee replacement. J Bone Joint Surg Br. 2009; 91(4): Matsumoto T, Muratsu H, Kubo S, Matsushita T, Kurosaka M, Kuroda R. Intraoperative soft tissue balance reflects minimum 5-year midterm outcomes in cruciate-retaining and posterior-stabilized total knee arthroplasty. J Arthroplasty. 2012; 27(9): 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(1): Becker R, Döring C, Denecke A, Brosz M. Expectation, satisfaction and clinical outcome of patients after total knee arthroplasty. Knee Surg Sports Traumatol Arthrosc. 2011; 19(9): Kwon SK, Kang YG, Chang CB, Sung SC, Kim TK. Interpretations of the clinical outcomes of the nonresponders to mail surveys in patients after total knee arthroplasty. J Arthroplasty. 2010; 25(1): 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(6): Khanna G, Singh JA, Pomeroy DL, Gioe TJ. Comparison of patient-reported and clinician-assessed outcomes following total knee arthroplasty. J Bone Joint Surg Am. 2011; 93(20):e111-e Insall JN, Dorr LD, Scott RD, Scott WN. Rationale of the Knee Society clinical rating system. Clin Orthop Relat Res. 1989; 248: 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 Clin Orthop Relat Res. 2009; 467(10): Mizner RL, Petterson SC, Clements KE, Zeni JA Jr, 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(5): Noble PC, Scuderi GR, Brekke AC, et al. Development of a new Knee Society scoring system. Clin Orthop Relat Res. 2012; 470(1): 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(1): Ishida K, Matsumoto T, Tsumura N, et al. Mid-term outcomes of computer-assisted total knee arthroplasty. Knee Surg Sports Traumatol Arthrosc. 2011; 19(7): Faul F, Erdfelder E, Lang AG, Buchner A. G*Power 3: a flexible statistical power analysis program for the social, behavioral, and biomedical sciences. Behav Res Methods. 2007; 39(2): Kolisek FR, McGrath MS, Marker DR, et al. Posterior-stabilized versus posterior cruciate ligament-retaining total knee arthroplasty. Iowa Orthop J. 2009; 29: Hirsch HS, Lotke PA, Morrison LD. The posterior cruciate ligament in total knee surgery: save, sacrifice, or substitute? Clin Orthop Relat Res. 1994; 309: Insall JN, Hood RW, Flawn LB, Sullivan DJ. The total condylar knee prosthesis in gonarthrosis: a five to nine-year follow-up of the first one hundred consecutive replacements. J Bone Joint Surg Am. 1983; 65(5): Lozano-Calderón SA, Shen J, Doumato DF, Greene DA, Zelicof SB. Cruciate-retaining vs posterior-substituting inserts in total knee arthroplasty: functional outcome comparison. J Arthroplasty. 2013; 28(2): Thomsen MG, Husted H, Otte KS, Holm G, Troelsen A. Do patients care about higher flexion in total knee arthroplasty? A randomized, controlled, double-blinded trial. BMC Musculoskelet Disord. 2013; 14: Healy WL, Sharma S, Schwartz B, Iorio R. Athletic activity after total joint arthroplasty. J Bone Joint Surg Am. 2008; 90(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(7): 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(1): 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(12): 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(10): e1132 Copyright SLACK Incorporated