The Reliability of the Tönnis Grading System in Patients Undergoing Hip Preservation
Bibliographic record
Abstract
Background:The presence of pre-existing osteoarthritis (OA) has been associated with poor results after hip arthroscopic surgery. There is limited evidence validating the currently available grading systems of hip OA in patients undergoing hip preservation.Purpose/Hypothesis:Our purpose was to evaluate the interobserver and intraobserver reliabilities of 2 grading systems in a group of patients undergoing hip preservation: the Tönnis grading system and a simple 4-choice Likert scale. The hypothesis was that interobserver and intraobserver reliabilities using the Tönnis grading system would be poor among surgeons experienced in hip preservation and that a 4-choice Likert scale would be more reliable.Study Design:Cohort study (diagnosis); Level of evidence, 3.Methods:A total of 100 hip radiographs were reviewed by 8 experienced hip preservation surgeons. Overall, 2 rounds of reviews were performed, at least 3 weeks apart, assessing for the presence, degree, and/or location of joint space narrowing, joint space asymmetry, subchondral cysts, osteophytes, and sclerosis. The radiographs were assigned a Tönnis grade as well as a Likert grade of OA, reported as none, mild, moderate, or severe. Statistical analysis was conducted to provide Fleiss kappa values with 95% CIs. Agreement was classified as poor for <0.00, slight for 0.00-0.20, fair for 0.21-0.40, moderate for 0.41-0.60, substantial for 0.61-0.80, and almost perfect for >0.80.Results:A total of 50 patients (28 female and 22 male) with a mean age of 42.8 ± 14.2 years (range, 19-70 years) were reviewed. The Tönnis grade demonstrated an interobserver kappa value of 0.30 (95% CI, 0.26-0.34). The Likert grade demonstrated an interobserver kappa value of 0.33 (95% CI, 0.28-0.37). All other measures demonstrated interobserver kappa values classified as slight or fair except for subchondral cysts which was moderate. Intraobserver reliabilities were statistically significantly higher than interobserver reliabilities. Intraobserver reliabilities for both the Tönnis grade (κ = 0.55 [95% CI, 0.51-0.60]) and Likert grade (κ = 0.59 [95% CI, 0.55-0.63]) demonstrated similar kappa values, consistent with moderate agreement. Subchondral cysts demonstrated the strongest interobserver (κ = 0.53) and intraobserver (κ = 0.85) reliabilities.Conclusion:Interobserver and intraobserver reliabilities were fair and moderate, respectively, for grading OA. Given the limited interobserver reliability, caution should be used when interpreting and translating studies that utilize the Tönnis grade or other rating to dictate treatment algorithms.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.012 | 0.043 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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 source (direct Gemma or distilled Codex), 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".