Validity and Internal Consistency of the New Knee Society Knee Scoring System
Bibliographic record
Abstract
BACKGROUND: In 2012, a new Knee Society Knee Scoring System (KSS) was developed and validated to address the needs for a scoring system that better encompasses the expectations, satisfaction, and physical involvement of a younger, more active population of patients undergoing TKA. Revalidating this tool in a separate population by individuals other than the developers of the scoring system seems important, because such replication would tend to confirm the generalizability of this tool. QUESTIONS/PURPOSES: The purposes of this study were (1) to validate the KSS using a separate sample of patients undergoing primary TKA; and (2) to evaluate the internal consistency of the KSS. METHODS: Intervention and control groups from a randomized controlled trial with no between-group differences were pooled. Preoperative and postoperative (6 weeks and 1 year) data were used. Patients with osteoarthritis undergoing primary TKA completed the patient-reported component of the KSS, Knee Injury and Osteoarthritis Outcome Score (KOOS), SF-12, two independent questions about expectations of surgery, and the Patient Acceptable Symptom State (PASS) single-question outcome. This study included 345 patients with 221 (64%) women, an average (SD) age of 64 (8.6) years, a mean (SD) body mass index of 32.9 (7.5) kg/m, and 225 (68%) having their first primary TKA. Loss to followup in the control group was 18% and loss to followup in the intervention group was 13%. We quantified cross-sectional (preoperative scores) and longitudinal validity (pre- to postoperative change scores) by evaluating associations between the KSS and KOOS subscales using Spearman's correlation coefficient. Preoperative known-group validity of the KSS symptoms and functional activity score was evaluated with a one-way analysis of variance across three levels of physical health status using the SF-12 Physical Component Score. Known-group validity of the KSS expectation score was evaluated with an unpaired t-test by comparing means across known expectation groups. Known-group validity of the KSS satisfaction score was evaluated with an unpaired t-test by comparing means across yes/no response groupings of the PASS single-question outcome. Internal consistency for each KSS subscale was evaluated with Cronbach's α. RESULTS: Cross-sectional validity (ie, associations at a single point in time) was supported because correlation coefficients between KSS symptoms, functional activities, and satisfaction scores and scores on the KOOS pain subscale ranged from 0.60 to 0.73 (all correlations p < 0.01). Values were similar for associations with the KOOS function in the activities of daily living (ADL) subscale (0.66-0.69) and less (0.41-0.58) for correlations with the other three KOOS subscales. Longitudinal validity (ie, associations of change scores between two time points) was also supported because correlation coefficients between KSS symptoms, functional activities, and satisfaction change scores and the KOOS pain and ADL change scores varied from 0.63 to 0.73. Correlation coefficients were lower for the other three KOOS subscale change scores, suggesting a weaker relationship with KOOS symptoms (0.48-0.53), sports (0.47-0.51), and quality of life (0.60-0.65) (all correlations p < 0.01). Known-group validity (ie, differences between groups that are known to differ on a given characteristic) was confirmed by between-group differences for the symptoms and functional activities score comparisons as well as the comparisons with the expectations and satisfaction scores of the KSS (all p < 0.01). Cronbach's α (ie, association among subscale items) varied from 0.68 (discretionary activities) to 0.94 (postoperative expectations) across four KSS subscales. CONCLUSIONS: Moderate-sized correlation coefficients and consistent differences between known groups support the validity of the KSS. Internal consistency values were also acceptable. The patient-reported subscales of the KSS are a valid and internally consistent outcome assessment for TKA.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.004 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.003 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".