RANKL Inhibition: A Novel Strategy to Decrease Femoral Head Deformity After Ischemic Osteonecrosis
Bibliographic record
Abstract
UNLABELLED: A novel therapeutic strategy to decrease the development of femoral head deformity after ischemic osteonecrosis was studied in a large animal model of total head infarction. RANKL inhibition through exogenous osteoprotegerin administration significantly decreased pathologic bone resorption and deformity during repair of the infarcted head. INTRODUCTION: Legg-Calvé-Perthes disease (LCPD) is a juvenile form of osteonecrosis of the femoral head that can produce permanent femoral head deformity (FHD) and premature osteoarthritis. The development of FHD in LCPD is closely associated with the repair process, characterized by a predominance of bone resorption in its early stage that produces a fragmented appearance and collapse of the femoral head. We present here a novel strategy to preserve the femoral head structure after ischemic osteonecrosis based on inhibition of interaction between RANK and RANKL using exogenous administration of osteoprotegerin (OPG-Fc) in a large animal model of ischemic osteonecrosis. MATERIALS AND METHODS: Ischemic osteonecrosis was surgically induced in 18 male piglets by placing a ligature tightly around the right femoral neck to disrupt the blood flow to the right femoral head. Two weeks after the induction of total head infarction, OPG-Fc or saline was administered subcutaneously to nine animals per group for 6 weeks. The contralateral, normal (left) femoral heads from the animals treated with saline served as normal, nondisease controls. All animals were killed at 8 weeks when severe FHD has been previously shown to occur because of the repair process dominated by osteoclastic bone resorption. Radiographic, histomorphometric, and immunohistochemical assessments were performed. RESULTS: Radiographic assessment showed significantly better preservation of the femoral head structure in the OPG-Fc group compared with the saline group. Epiphyseal quotient (the ratio of epiphyseal height to diameter) was significantly higher in the OPG-Fc group (0.41 +/- 0.09) compared with the saline group (0.24 +/- 0.08, p < 0.001). Histomorphometric assessment revealed a significant reduction in the number of osteoclasts present in the OPG-Fc group (5.9 +/- 5.3mm(-2)) compared with the saline group (39.6 +/- 13.8 mm(-2), p < 0.001). Trabecular bone volume, number, and separation were significantly better preserved in the OPG-Fc group compared with the saline group (p < 0.001). No significant difference in femoral length was observed between the OPG-Fc and saline groups. Immunostaining revealed the presence of OPG-Fc only within the blood vessels, with no apparent staining of bone matrix or trabecular bone surfaces. CONCLUSIONS: To our knowledge, this is the first study to show that RANKL inhibition decreases bone resorption and FHD after ischemic osteonecrosis. Because RANKL inhibitors do not bind to bone, their effects on resorption are reversible as the drug is cleared from circulation. The reversible nature of RANKL inhibitors is very appealing for treating pediatric bone diseases such as LCPD, where the resorptive stage of the disease lasts for 1-2 years.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 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 | 0.001 |
| 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".