The Therapeutic Effect of Intra-articular Normal Saline Injections for Knee Osteoarthritis: A Meta-analysis of Evidence Level 1 Studies
Bibliographic record
Abstract
BACKGROUND: Intra-articular normal saline (IA-NS) injections have been utilized as a placebo in a number of randomized controlled trials pertaining to the management of knee osteoarthritis (OA); however, it is believed that these "placebo" injections may have a therapeutic effect that has not been quantified in the literature. PURPOSE: To (1) quantify the effect of IA-NS injections on patient-reported outcomes (PROs) and (2) compare postinjection PROs to established minimal clinically important difference (MCID) criteria to demonstrate a potential therapeutic effect. STUDY DESIGN: Meta-analysis. METHODS: A review was conducted to identify all randomized, placebo-controlled trials on injection therapy for knee OA between 2006 and 2016. Patient demographics and PROs before the injection and at 3 and 6 months after the injection were collected for patients in the IA-NS injection group in each study. A random-effects model was used to compare preinjection scores and scores at each postinjection time point in a pairwise fashion. RESULTS: . There was only sufficient information to perform analyses of visual analog scale (VAS) pain and Western Ontario and McMaster Universities Arthritis Index (WOMAC) total scores. At 3 months after the IA-NS placebo injection, there was a significant improvement in VAS pain scores (mean difference [MD], 12.10 [95% CI, 3.27 to 20.93]; P = .007), whereas improvement in the WOMAC total scores approached but did not reach statistical significance (MD, 19.75 [95% CI, -0.50 to 40.09]; P = .06). At 6 months, both VAS pain scores (MD, 16.62 [95% CI, 12.13-21.10]; P < .00001) and WOMAC total scores (MD, 11.34 [95% CI, 7.03-15.65]; P < .00001) were significantly improved in comparison to preinjection values. Furthermore, improvements in both the VAS pain and WOMAC total scores at 6 months were clinically significant (MCID, 1.37 and 9, respectively). CONCLUSION: The administration of an IA-NS placebo injection yields a statistically and clinically meaningful improvement in PROs up to 6 months after the injection in patients with knee OA. This observation supports the notion that the so-called placebo effect for IA-NS injections achieves a clinically meaningful response in patients with OA when provided during comparison studies to an active treatment group (ie, hyaluronic acid).
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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 | 0.017 | 0.042 |
| Meta-epidemiology (narrow) | 0.004 | 0.002 |
| Meta-epidemiology (broad) | 0.023 | 0.049 |
| Bibliometrics | 0.006 | 0.006 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.004 | 0.002 |
| Open science | 0.003 | 0.001 |
| Research integrity | 0.003 | 0.003 |
| Insufficient payload (model declined to judge) | 0.005 | 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".