Interjoint coordination in lower limbs in patients with a rupture of the anterior cruciate ligament of the knee joint
Bibliographic record
Abstract
Previous studies of movement kinematics in patients with a ruptured anterior cruciate ligament (ACL) have focused on changes in angular displacement in a single joint, usually flexion/extension of the knee. In the present study, we investigated the effect of an ACL injury on the overall limb interjoint coordination. We asked healthy and chronic ACL-deficient male subjects to perform eight types of movements: forward squats, backward squats, sideways squats, squats on one leg, going up a step, going down a step, walking three steps, and stepping in place. Depending on the movement concerned, we applied principal component (PC) analysis to 3 or 4 degrees of freedom (DFs): thigh flexion/extension, knee flexion/extension, ankle flexion/extension, thigh abduction/adduction. The first three DFs were investigated in all movements. PC analysis identifies linear combinations of DFs. Movements with a fixed ratio between DFs are thus described by only one PC or synergy. PCs were computed for the entire movement as well as for the period of time when the foot was in contact with the ground. For both the control and the injured groups, two synergies (PC vectors) usually accounted for more than 95% of the DFs' angular excursions. It was possible to describe 95-99% of some movements using only one synergy. Compared to control subjects, injured subjects employed different synergies for going up a step, walking three steps, squatting sideways, and squatting forward, both in the injured and uninjured legs. Those movements may thus be more indicative of injury than other movements. Although ACL-deficiency did not increase asymmetry (angle between the PCs of the same movement performed on the right and the left sides), this result is not conclusive because of the comparatively low number of subjects who participated in the study. However, the finding that synergies in both legs of patients were different from those in control subjects for going up a step and walking three steps suggests that interjoint coordination was affected for both legs, so that the asymmetry index might have been preserved despite the injury. There was also a relationship between the asymmetry index for squatting on one leg, squatting forward, walking three steps and some of the outcomes of the knee injury and osteoarthritis outcome score (pain, symptoms, activities of daily living, sport and recreation function, and knee-related quality of life). This suggests that significant differences in the asymmetry index could be obtained if more severely-injured patients participated in this study. It is possible that subjects compensated for their mechanical deficiencies by modifying muscle activation patterns. Synergies were not only modified in injured subjects, but also rearranged: the percentage of movement explained by the first PC was different for the injured and/or uninjured legs of patients, as compared to the legs of the control group, for going up a step, going down a step, walking three steps, and squatting forward. We concluded that the analysis of interjoint coordination may be efficient in characterizing motor deficits in people with knee injuries.
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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) | 0.001 | 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".