Skip to main content
Log in

The minimal clinically important difference for Knee Society Clinical Rating System after total knee arthroplasty for primary osteoarthritis

  • Knee
  • Published:
Knee Surgery, Sports Traumatology, Arthroscopy Aims and scope

Abstract

Purpose

The Knee Society Clinical Rating System (KS) is one of the most popular tools used to assess patient outcome after total knee arthroplasty (TKA), but its minimal clinically important difference (MCID) has not been identified. This study aims to identify the MCID of KS function score (KS-FS) and knee score (KS-KS) after TKA in patients with primary knee osteoarthritis.

Methods

The authors retrospectively analysed patients who underwent TKA for primary knee osteoarthritis between 2005 and 2015 in a single institution. KS-FS, KS-KS, and Oxford Knee Score (OKS) were collected pre-operatively and 2 years post-operatively. Patient satisfaction with TKA at 2 years was also collected. Anchor-based approach with 2 external indicators was used. The MCID for KS-FS and KS-KS was determined using simple linear regression according to patient satisfaction with TKA and the MCID of OKS.

Results

The mean age of the 550 subjects studied was 66 ± 8 years. There were 373 (67.8 %) female subjects. The KS-FS improved by 22.8 (95 % CI 20.9–24.6) points, and the KS-KS improved by 44.4 (95 % CI 42.6–46.3) points. The MCID identified for KS-FS is between 6.1 (95 % CI 5.1–7.1) and 6.4 (95 % CI 4.4–8.4) and between 5.3 (95 % CI 4.3–6.3) and 5.9 (95 % CI 3.9–7.8) for KS-KS.

Conclusions

This is the first study, to the knowledge of the authors, to identify the MCID of KS. This will allow future trials to have an accurate prediction of sample size. Clinically, physicians will be able to better interpret outcomes of TKA studies to guide a treatment option.

Level of evidence

IV.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Subscribe and save

Springer+ Basic
EUR 32.99 /Month
  • Get 10 units per month
  • Download Article/Chapter or Ebook
  • 1 Unit = 1 Article or 1 Chapter
  • Cancel anytime
Subscribe now

Buy Now

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Fig. 1
Fig. 2
Fig. 3

Similar content being viewed by others

References

  1. 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(11):2618–2624

    Article  PubMed  Google Scholar 

  2. Bagsby D, Pierson JL (2015) Functional outcomes of simultaneous bilateral versus unilateral total knee arthroplasty. Orthopedics 38(1):e43–e47

    Article  PubMed  Google Scholar 

  3. Baker PN, van der Meulen JH, Lewsey J, Gregg PJ (2007) The role of pain and function in determining patient satisfaction after total knee replacement. Data from the National Joint Registry for England and Wales. J Bone Joint Surg Br 89:893–900

    Article  CAS  PubMed  Google Scholar 

  4. Beard DJ, Harris K, Dawson J, Doll H, Murray DW, Carr AJ, Price AJ (2015) Meaningful changes for the Oxford hip and knee scores after joint replacement surgery. J Clin Epidemiol 68(1):73–79

    Article  PubMed  PubMed Central  Google Scholar 

  5. Bellamy N, Buchanan WW, Goldsmith CH, Campbell J, Stitt LW (1988) 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 15:1833–1840

    CAS  PubMed  Google Scholar 

  6. Charlson ME, Pompei P, Ales KL, MacKenzie C (1987) A new method of classifying prognostic comorbidity in longitudinal studies: development and validation. J Chronic Dis 40(5):373–383

    Article  CAS  PubMed  Google Scholar 

  7. 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(8):1933–1939

    Article  CAS  PubMed  Google Scholar 

  8. Dawson J, Fitzpatrick R, Murray D, Carr A (1998) Questionnaire on the perceptions of patients about total knee replacement. J Bone Joint Surg Br 80:63–69

    Article  CAS  PubMed  Google Scholar 

  9. Donaldson J, Joyner J, Tudor F (2015) Current controversies of alignment in total knee replacements. Open Orthop J 30(9):489–494

    Article  Google Scholar 

  10. Dowsey MM, Choong PF (2013) The utility of outcome measures in total knee replacement surgery. Int J Rheumatol 2013:506518. doi:10.1155/2013/506518

    Article  PubMed  PubMed Central  Google Scholar 

  11. Escobar A, Quintana JM, Bilbao A, Aróstegui I, Lafuente I, Vidaurreta I (2007) Responsiveness and clinically important differences for the WOMAC and SF-36 after total knee replacement. Osteoarthr Cartil 15(3):273–280

    Article  CAS  PubMed  Google Scholar 

  12. Escobar A, García Pérez L, Herrera-Espiñeira C, Aizpuru F, Sarasqueta C, Sáenz Gonzalez, de Tejada M, Quintana JM, Bilbao A (2013) Total knee replacement; minimal clinically important differences and responders. Osteoarthr Cartil 21(12):2006–2012

    Article  CAS  PubMed  Google Scholar 

  13. Gulati A, Pandit H, Jenkins C, Chau R, Dodd CA, Murray DW (2009) The effect of leg alignment on the outcome of unicompartmental knee replacement. J Bone Joint Surg Br 91(4):469–474

    Article  CAS  PubMed  Google Scholar 

  14. Ha CW, Park YB, Song YS, Kim JH, Park YG (2015) Increased range of motion is important for functional outcome and satisfaction after total knee arthroplasty in Asian patients. J Arthroplasty. doi:10.1016/j.arth.2015.12.018

    Google Scholar 

  15. Insall JN, Dorr LD, Scott RD, Scott WN (1989) Rationale of the Knee Society Clinical Rating System. Clin Orthop Relat Res 248:13–14

    Google Scholar 

  16. Jacobs CA, Christensen CP (2009) Correlations between knee society function scores and functional force measures. Clin Orthop Relat Res 467(9):2414–2419

    Article  PubMed  PubMed Central  Google Scholar 

  17. Lee WC, Kwan YH, Yeo SJ (2016) Severe bilateral fixed flexion deformity-simultaneous or staged total knee arthroplasty? J Arthroplasty 31(1):128–131

    Article  PubMed  Google Scholar 

  18. Lingard EA, Katz JN, Wright RJ, Wright EA, Sledge CB, Kinemax Outcomes Group (2001) Validity and responsiveness of the Knee Society Clinical Rating System in comparison with the SF-36 and WOMAC. J Bone Joint Surg Am 83-A(12):1856–1864

    Article  CAS  PubMed  Google Scholar 

  19. Miner AL, Lingard EA, Wright EA, Sledge CB, Katz JN, Kinemax Outcomes Group (2003) Knee range of motion after total knee arthroplasty: how important is this as an outcome measure? J Arthroplasty 18(3):286–294

    Article  PubMed  Google Scholar 

  20. 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

    Article  PubMed  Google Scholar 

  21. Norman GR, Sloan JA, Wyrwich KW (2004) The truly remarkable universality of half a standard deviation: confirmation through another look. Expert Rev Pharmacoecon Outcomes Res 4(5):581–585

    Article  PubMed  Google Scholar 

  22. Peters PG, Herbenick MA, Anloague PA, Markert RJ, Rubino LJ III (2011) Knee range of motion: reliability and agreement of 3 measurement methods. Am J Orthop (Belle Mead NJ) 40(12):E249–E252

    Google Scholar 

  23. 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(2):102–109

    Article  PubMed  Google Scholar 

  24. Roos EM, Roos HP, Ekdahl C, Lohmander LS (1998) Knee injury and osteoarthritis outcome score (KOOS)—validation of a Swedish version. Scand J Med Sci Sports 8:439–448

    Article  CAS  PubMed  Google Scholar 

  25. Sabouret P, Lavoie F, Cloutier JM (2013) Total knee replacement with retention of both cruciate ligaments: a 22-year follow-up study. Bone Joint J 95-B(7):917–922

    Article  CAS  PubMed  Google Scholar 

  26. Seah RB, Yeo SJ, Chin PL, Yew AK, Chong HC, Lo NN (2014) Evaluation of medial-lateral stability and functional outcome following total knee arthroplasty: results of a single hospital joint registry. J Arthroplasty 29(12):2276–2279

    Article  PubMed  Google Scholar 

  27. Silva AL, Demange MK, Gobbi RG, da Silva TF, Pecora JR, Croci AT (2012) Translation and validation of the knee society score-KSS for Brazilian Portugese. Acta Ortop Bras 20(1):25–30

    Article  PubMed  PubMed Central  Google Scholar 

  28. Terwee CB, Mokkink LB, Knol DL, Ostelo RW, Bouter LM, de Vet HC (2012) Rating the methodological quality in systematic reviews of studies on measurement properties: a scoring system for the COSMIN checklist. Qual Life Res 21(4):651–657

    Article  PubMed  Google Scholar 

  29. Walenkamp MM, de Muinck Keizer RJ, Goslings JC, Vos LM, Rosenwasser MP, Schep NW (2015) The minimum clinically important difference of the patient-rated wrist evaluation score for patients with distal radius fractures. Clin Orthop Relat Res 473(10):3235–3241

    Article  PubMed  PubMed Central  Google Scholar 

  30. Ware JE Jr, Sherbourne CD (1992) The MOS 36-item short-form health survey (SF-36). I. Conceptual framework and item selection. Med Care 30:473–483

    Article  PubMed  Google Scholar 

  31. Ware J, Kosinski M, Keller SD (1996) A 12-Item short-form health survey: construction of scales and preliminary tests of reliability and validity. Med Care 34:220–233

    Article  PubMed  Google Scholar 

Download references

Acknowledgments

The authors would like to thank all the surgeons for giving the permission for the usage of their data, and the staff at Orthopaedic Diagnostic Centre for assisting in the collation of the data presented in this study.

Author information

Authors and Affiliations

Authors

Corresponding author

Correspondence to Wu Chean Lee.

Ethics declarations

Conflict of interest

The authors declare that they have no conflict of interest.

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Lee, W.C., Kwan, Y.H., Chong, H.C. et al. 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 (2017). https://doi.org/10.1007/s00167-016-4208-9

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s00167-016-4208-9

Keywords

Navigation