Abstract
This reply addresses Wang et al.’s comments on our prior work and clarifies that the 34.5-point Knee Society Score threshold was derived from our previously validated, anchor-based approach. We agree that future research should refine predictive models by establishing consensus, standardised minimal clinically important difference cutoffs to enhance applicability and reliability in real-world clinical settings.
Subject terms: Outcomes research, Osteoarthritis
We thank Wang et al. for their perspective on our recently published work1, including the discussion regarding the use of alternative minimal clinical important difference (MCID) thresholds2 for the Knee Society Score (KSS) in assessing patient satisfaction. We welcome the dialogue and agree that selecting an appropriate MCID threshold is critical for evaluating clinically meaningful patient satisfaction after total knee arthroplasty (TKA).
Several prior studies have explored the MCID cutoffs for KSS2–4, however, each has methodological limitations, including small sample sizes, non-standard calculation approaches, retrospective anchors susceptible to substantial response-shift bias, and collapsed or absent ‘no-change’ categories. Currently, no standardised MCID threshold exists for the KSS. In our study, we therefore adopted a threshold of 34.5 points for KSS knee score based on our previous work, which used a well-established, anchor-based linear regression method validated in Singaporean patients who underwent primary or revision TKA with follow-up at 6 months and 2 years4,5. Furthermore, a previous study also suggested that that higher thresholds—approximately 39–40 points—may be useful in identifying patients who experience substantial clinical benefit after TKA3. In addition, the median of preoperative KSS score is 36 (interquartile range [23, 50]), with 8.3% of them had preoperative KSS score65.5 that were mathematically unable to MCID. A comprehensive evaluation approach is warranted to provide thorough evaluation to those patients who may show ceiling effects when using a single metric.
In our view, the primary contribution of our paper is to provide the first multimodal, machine learning-based model to predict patient dissatisfaction across multiple scoring systems. We agree with Wang et al. that future studies are warranted to determine clinically meaningful MCID thresholds for multiple patient-reported outcome measures in large-scale, prospective cohorts. We anticipate that future work will extend and refine the models we present, incorporating richer clinical information and, ultimately, consensus-based, standardised MCID cutoffs for deployment in real-world clinical settings.
Acknowledgements
This study was funded by the Singhealth Duke-NUS Musculoskeletal Sciences Academic Clinical Programme Nurturing Clinician Scientist Scheme (NCSS) Research Support Grant. The funder played no role in study design, data collection, analysis and interpretation of data, or the writing of this manuscript.
Author contributions
X.D.L. and Y.N.L. drafted the manuscript; W.H., M.L.L., and M.H.L.L. reviewed the manuscript. All authors have read and approved the manuscript.
Data availability
The dataset used in this study is protected patient information for which restricted access is permitted.
Competing interests
The authors declare no competing interests.
Footnotes
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
These authors contributed equally: Xiaodi Liu, Yingnan Liu.
References
- 1.Liu, X., Liu, Y., Lee, M. L., Hsu, W. & Liow, M. H. L. Identifying who are unlikely to benefit from total knee arthroplasty using machine learning models. npj Digit. Med.7, 266 (2024). [DOI] [PMC free article] [PubMed] [Google Scholar]
- 2.Lee, W. C., Kwan, Y. H., Chong, H. C. & Yeo, S. J. 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). [DOI] [PubMed] [Google Scholar]
- 3.Lizaur-Utrilla, A., Gonzalez-Parreño, S., Martinez-Mendez, D., Miralles-Muñoz, F. A. & Lopez-Prats, F. A. Minimal clinically important differences and substantial clinical benefits for Knee Society Scores. Knee Surg. Sports Traumatol. Arthrosc.28, 1473–1478 (2020). [DOI] [PubMed] [Google Scholar]
- 4.Khow, Y. Z. et al. Defining the minimal clinically important difference for the Knee Society Score following revision total knee arthroplasty. Knee Surg. Sports Traumatol. Arthrosc.30, 2744–2752 (2022). [DOI] [PubMed] [Google Scholar]
- 5.Liow, M. H. L. et al. Robotic-assisted total knee arthroplasty may lead to improvement in quality-of-life measures: a 2-year follow-up of a prospective randomized trial. Knee Surg. Sports Traumatol. Arthrosc.25, 2942–2951 (2017). [DOI] [PubMed] [Google Scholar]
Associated Data
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Data Availability Statement
The dataset used in this study is protected patient information for which restricted access is permitted.