THE CAM DEFORMITY IN PATIENTS WITH FEMOROACETABULAR IMPINGEMENT DEMONSTRATES LOSS OF PROTEOGLYCAN CONTENT
Bibliographic record
Abstract
Summary Statement This study quantifies compositional differences in cartilage between CAM deformities of symptomatic FAI patients and normal cadaver controls. It shows a resemblance of CAM-FAI cartilage with those of osteoarthritic hips, objectively supporting previous hypothesis of abnormal contact stresses in CAM-FAI. Introduction Degeneration of cartilage within articular joints is a pathological feature of osteoarthritis (OA). Femoroacetabular impingement (FAI), a condition of abnormal contact between the articular surfaces of the femur and acetabulum, has been widely associated with early onset OA of the hip. The purpose of this study was to quantitatively compare the proteoglycan (PG) content of the weight-bearing cartilage in surgical FAI patients versus those of cadavers without FAI. Patients and Methods Osteochondral bone plugs were taken from the antero-superior weight-bearing surface of cam-deformities on the femoral heads of 11 surgical cam-FAI patients. These were compared to control specimens taken from 11 cadaveric hips (7 donors) at approximately the same location. The PG content of the specimens were then histologically compared using the model presented by Martin et al. In this method, Safranin-O binds to chondroitin sulfate, a PG abundant in cartilage, allowing it to be visualised and quantitatively compared. Specifically, the specimens were fixed in formalin, decalcified in EDTA and then sectioned to 7um thick. They were then stained with Safranin-O, which binds specifically and stoichiometrically with proteoglycan. This model allows for quantitative comparison of PG content whereby the red content (R c ) of the sample is linearly correlated with the amount of PG present in the sample when viewed under 4x microscopic magnification. Here, the red content was sampled by depth coordinate with superficial and deep zones analyzed. Results In general, the R C in the cartilage of surgical patients was lower than that of the cadaveric controls in both the superficial and deep layers tested. This correlates to a decrease in the PG of the test subjects. In the surgical specimens, R C ranged from 0 – 31.9 in the superficial layer and 0 – 139.6 in the deep. When compared by layers, the R C of the superficial 30% specimens averaged an R C of 17.5 compared to 88.6 in the cadaveric controls. This represents an 80.2% depletion in the PG content. In the deep 70% layer, the average R C of the test subjects was 52.4, compared with 129.2 in the cadaveric controls. This represents a 59% depletion in the PG content of the deep layer. These results show large compositional change in the cartilage of surgical FAI versus control specimens that were statistically significant in all levels (superficial, deep, total yielding p Discussion The idea of abnormal cartilage at the cam deformity has been previously demonstrated through similar resection and staining techniques. Wagner et al showed cellular activity and qualitatively noted PG depletion in the cartilage on the Cam deformity, consistent with OA. However a quantitative assessment of PG content provides a better estimate of impingement severity and disease state. Results from this current study objectively corroborate previously obtained qualitative data, supporting existing hypothesis of abnormal contact stresses in cam-FAI while giving a more robust, objective quantification of cartilage breakdown at CAM sites.
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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 | 0.001 |
| 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) | 0.003 | 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".