Lumbar Multifidus Muscle Activation Differs In Older Adults With Symptomatic Knee Osteoarthritis With And Without Low Back Pain
Bibliographic record
Abstract
PURPOSE: Compare lumbar multifidus (LM) activation in older adults with symptomatic knee osteoarthritis (KOA) with and without low back pain (LBP) and the association between muscle activation and subjective function. METHODS: Ten older adults with KOA and LBP (5F/5M, 63.2 ± 10.2 years, 95.6 ± 27.3 kg, 172.3 ± 12.4 cm), and 12 adults with KOA (5F/7M, 65.3 ± 9.1 years, 85.0 ± 23.3 kg, 170.4 ± 11.3 cm), completed the Knee Injury and Osteoarthritis Outcome Score (KOOS), and the Western Ontario and McMaster Universities Arthritis Index (WOMAC). LBP was defined as having greater than a score of 12 on the Oswestry Disability Index. Resting LM thickness and dynamic LM thickness during a modified Sorensen test were obtained using ultrasound at the L4-L5 facet joint. Three images were measured and averaged for resting and dynamic images. LM activation ratio (AR) was calculated as the ratio of contracted LM thickness to resting LM thickness. Group differences in AR were compared using an independent t-test and Cohen’s d effect sizes were calculated. Associations between LM AR and subjective function for each group were evaluated using Pearson’s correlation coefficient (r). RESULTS: Patients with KOA and LBP had lower LM AR when compared to those with only KOA (MD = .22 ± .23%; d = .94; p = .04). Greater LM AR was associated with greater disability on WOMAC subscales (pain: r = .66, p = .02; stiffness: r = .69, p = .01; physical function: r = .66, p = .02) and total WOMAC total (r = .68, p = .01) in the KOA group but not in the KOA + LBP group (pain: r = -.35, p = .33; stiffness: r = -.31, p = .38; physical function: r = -.09, p = .81; total score: r = -.20, p = .57). Greater LM AR was also associated with greater disability on KOOS subscales in the KOA group (symptoms: r = -.63, p = .03; ADL: r = -.61, p = .03; QoL: r = -.77, p < .01) but not in the KOA + LBP group. LM AR was not significantly correlated with KOOS pain subscale in both KOA (r = -.51, p = .09) and KOA + LBP groups (r = .43, p = .21). CONCLUSIONS: Patients with KOA + LBP demonstrate lower LM activation than those with only KOA. Further, differences in AR-subjective function associations between the groups suggests that once patients with KOA develop LBP, it is too late to clinically modify their low back muscle activation. Thus, clinical importance should be given to improving low back muscle strength and activation in KOA patients.
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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 | 0.000 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| 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".