Abstract
Purpose
There is a paucity of literature defining the minimal clinically important difference (MCID) for the Knee Society Scores (KSS) after total knee arthroplasty (TKA), and no data on the substantial clinical benefit (SCB) for KSS have been reported. The purpose of this study was to determine MCID and SCB for the KSS in patients with primary TKA.
Methods
The median age of patients was 71.6 (range 50–88) years, and 60.3% were females 507 patients with TKA were prospectively enrolled. Patients completed the KSS before surgery and at second postoperative year. The MCID values of the KSS were estimated using anchor-based method, distribution-based method and receiver operating characteristic (ROC) curve analysis with calculation of the area under curve (AUC). SCB was estimated using ROC.
Results
The MCID for KSS-knee score was 7.2 points by the anchor-based method, 7.2 by the distribution-based method, and using a ROC analysis the cutoff point was 8.9 points with an AUC of 0.75. For KSS-function score, the MCID values were 9.7, 6.3, and 10.3 (AUC 0.71), respectively. SCB values were 39.7 points (AUC 0.74) for the KSS-knee score, and 38.6 (AUC 0.76) for the KSS-function score. Logistic regression showed age and Charlson index to negatively affect the changes in KSS.
Conclusion
Different methods for MCID calculation lead to different results. With the use of ROC curve analysis, patients with an improvement of at least 9 points for KSS-knee and 10 points for KSS-function scores experience a clinically important change, whereas those who have at least an improvement of 40 points for KSS-knee and 39 points for KSS-function scores experience a substantial clinical benefit. These findings can ensure clinical improvement from the patient’s perspective and also aid in interpreting results from clinical studies.
Level of evidence
III.
Similar content being viewed by others
References
American Society of Anesthesiologists (2008) Relative value guide 2008. https://www.asahq.org. Accessed 17 Dec 2017
Ares O, Castellet E, Macule F, Leon V, Montanez E, Freire A, Hinarejos P, Montserrat F, Amillo JR (2013) Translation and validation of ‘The Knee Society Clinical Rating System’ into Spanish. Knee Surg Sports Traumatol Arthrosc 21:2618–2624
Charlson M, Szatrowski TP, Peterson J, Gold J (1994) Validation of a combined comorbidity index. J Clin Epidemiol 47:1245–1251
Clement ND, Burnett R (2013) Patient satisfaction after total knee arthroplasty is affected by their general physical well-being. Knee Surg Sports Traumatol Arthrosc 21:2638–2646
Clement ND, Macdonald D, Burnett R (2013) Predicting patient satisfaction using the Oxford knee score: where do we draw the line? Arch Orthop Trauma Surg 133:689–694
Clement ND, MacDonald D, Simpson AH (2014) The minimal clinically important difference in the Oxford Knee Score and short form 12 score after total knee arthroplasty. Knee Surg Sports Traumatol Arthrosc 22:1933–1939
Cook CE (2008) Clinimetrics corner. The minimal clinically important change score (MCID): a necessary pretense. J Man Manip Ther 16:e82–e83
Copay AG, Subach BR, Glassman SD, Polly DW Jr, Schuler TC (2007) Understanding the minimum clinically important difference: a review of concepts and methods. Spine J 7:541–546
Crosby RD, Kolotkin RL, Williams GR (2003) Defining clinically meaningful change in health-related quality of life. J Clin Epidemiol 56:395–407
Dawson J, Fitzpatrick R, Murray D, Carr A (1998) Questionnaire on the perceptions of patients about total knee replacement. J Bone Jt Surg Br 80:63–69
Ghomrawi HMK, Mancuso CA, Dunning A, Gonzalez Della Valle A, Alexiades M, Cornell C, Sculco T, Bostrom M, Mayman D, Marx RG, Westrich G, O’Dell M, Mushlin AI (2017) Do surgeon expectations predict clinically important improvements in WOMAC scores after THA and TKA? Clin Orthop Relat Res 475:2150–2158
Glassman SD, Copay AG, Berven SH, Polly DW, Subach BR, Carreon LY (2008) Defining substantial clinical benefit following lumbar spine arthrodesis. J Bone Jt Surg Am 90:1839–1847
Insall JN, Dorr LD, Scott RD, Scott WN (1989) Rationale of the Knee Society clinical rating system. Clin Orthop Relat Res 248:13–14
Jacobs CA, Christensen CP (2009) Correlations between knee society function scores and functional force measures. Clin Orthop Relat Res 467:2414–2419
Klit J, Jacobsen S, Rosenlund S, Sonne-Holm S, Troelsen A (2014) Total knee arthroplasty in younger patients evaluated by alternative outcome measures. J Arthroplasty 29:912–917
Koskinski M, Zhao SZ, Deshiya S, Osterhaus JT, Ware JE (2000) Determining minimally important changes in generic and disease-specific health-related quality of life questionnaires in clinical trials of rheumatoid arthritis. Arthritis Rheum 43:1478–1487
Lee WC, Kwan YH, Chong HC, Yeo SJ (2017) The minimal clinically important difference for Knee Society Clinical Rating System after total knee arthroplasty for primary osteoarthritis. Knee Surg Sports Traumatol Arthrosc 25:3354–3359
Noble PC, Conditt MA, Cook KF, Mathis KB (2006) The John Insall award: patient expectations affect satisfaction with total knee arthroplasty. Clin Orthop Relat Res 452:35–43
Revicki D, Hays RD, Cella D, Sloan J (2008) Recommended methods for determining responsiveness and minimally important differences for patient-reported outcomes. J Clin Epidemiol 61:102–109
Shirley ED, Sanders JO (2013) Patient satisfaction: implications and predictors of success. J Bone Jt Surg Am 95:e69
Tashjian RZ, Deloach J, Green A, Porucznik CA, Powell AP (2010) Minimal clinically important differences in ASES and simple shoulder test scores after nonoperative treatment of rotator cuff disease. J Bone Joint Surg Am 92:296–303
Terwee CB, Roorda LD, Dekker J, Bierma-Zeinstra SM, Peat G, Jordan KP, Croft P, de Vet HC (2010) Mind the MIC: large variation among populations and methods. J Clin Epidemiol 63:524–534
Wells G, Beaton D, Shea B, Boers M, Simon L, Strand V, Brooks P, Tugwell P (2001) Minimal clinically significant important differences: review of methods. J Rheumatol 28:406–412
Funding
This study had no funding.
Author information
Authors and Affiliations
Corresponding author
Ethics declarations
Conflict of interest
The authors declare that they have no conflict of interest.
Ethical approval
The present study was approved by the Institutional Ethics Committee of the Elda University Hospital, Miguel Hernandez University, Alicante, Spain (ID number: PI2012-098), and informed consent was obtained.
Additional information
Publisher's Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Rights and permissions
About this article
Cite this article
Lizaur-Utrilla, A., Gonzalez-Parreño, S., Martinez-Mendez, D. et al. Minimal clinically important differences and substantial clinical benefits for Knee Society Scores. Knee Surg Sports Traumatol Arthrosc 28, 1473–1478 (2020). https://doi.org/10.1007/s00167-019-05543-x
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00167-019-05543-x