The Biomechanics of Sit-to-Stand and Physical Performance in Patellofemoral Osteoarthritis
Bibliographic record
Abstract
Osteoarthritis (OA) of the knee is common in Western society. OA of the patellofemoral (PF) compartment of the knee is prevalent in adults greater than 55 years of age. Isolated radiographic PFOA is present in 13.6-24% of females and 11-15.4% of males with knee pain. Biomechanical factors such as tibiofemoral alignment and high joint stress are associated with the development and progression of PFOA. PF joint stress is high when the quadriceps contracts with the knee in a position of extreme flexion, such as rising from sitting. The purposes of this study were to determine 1) the triplanar biomechanics of the hips and knees during sit-to-stand (STS) for persons with PFOA versus age- and gender-matched control subjects, 2) the impact of PFOA on physical performance, perceived functional status, and pain, and 3) the relationship between knee kinematics during STS and physical performance. The biomechanics of STS was examined using a video-based motion analysis system and two force plates. Physical performance was measured with the Timed Up and Go (TUG) and Fifty-Foot Walk (FFW) tests. Perceived functional status, pain, and stiffness were measured using the Western Ontario and McMaster University Osteoarthritis Index (WOMAC) questionnaire. Knee pain was measured with a Visual Analog Scale (VAS) following STS, TUG, and FFW. Persons with PFOA required a significantly longer time to perform STS and the TUG as compared to healthy controls. The PFOA group demonstrated greater hip flexion and knee abduction versus the control group. The hip and knee moments were significantly different with the PFOA group demonstrating greater hip extension, hip abduction, hip external rotation, knee extension, and knee adduction moments. Persons with PFOA were found to have significantly less perceived physical function, greater stiffness, and greater pain. Pain following STS, TUG, and FFW were all greater in the PFOA group. No significant association was found between any knee angle and time to perform the TUG or the FFW. These results indicate that dynamic malalignment of the TF joint is present during STS in persons with PFOA. This may contribute to the increased pain and decreased function in persons with PFOA.
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| 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".