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Quantifying the extent of femoral head involvement in osteonecrosis
Sebastian F Cherian1, Alan Laorr, Khaled J Saleh
1Department of Radiology, University of Minnesota, Minneapolis 55455, USA.
Insights
Three methods for quantifying femoral head osteonecrosis are reliable and reproducible. These methods accurately predict subchondral collapse, aiding clinical decision-making for patients with osteonecrosis of the femoral head.
Area of Science:
- Orthopedic surgery
- Radiology
- Biostatistics
Background:
- Quantifying femoral head osteonecrosis extent lacks a standardized, reliable method.
- Existing methods for assessing osteonecrosis of the femoral head show variability.
- Establishing reliable quantification is crucial for prognostic accuracy.
Purpose of the Study:
- To evaluate the reliability and prognostic accuracy of three common methods for quantifying femoral head osteonecrosis.
- To compare interobserver and intraobserver agreement for each quantification method.
- To determine the predictive value of each method for subchondral collapse.
Main Methods:
- Three methods (index of necrotic extent, modified index, percentage involvement) were used by three observers on 39 hips with stage I/II osteonecrosis.
- Interobserver and intraobserver agreement were assessed for each method.
- Statistical analysis determined the prognostic significance for predicting subchondral collapse.
Main Results:
- All three methods demonstrated significant agreement among observers (p < 0.001).
- Substantial to nearly perfect agreement was observed for the index of necrotic extent and percentage involvement.
- All three methods proved to be significant predictors of subchondral fracture (p < 0.05).
Conclusions:
- The index of necrotic extent, modified index, and percentage involvement are reproducible and reliable for quantifying femoral head osteonecrosis.
- These methods can be confidently used in clinical practice.
- The methods effectively identify hips at high risk for subchondral collapse.
Background:
There are numerous methods for quantifying the extent of osteonecrosis of the femoral head. However, there is no consensus regarding which method is the most reliable. The purpose of this study was to determine the reliability and prognostic accuracy of three commonly used methods for quantifying the extent of osteonecrosis of the femoral head.
Methods:
Thirty-nine hips in twenty-five patients who had stage-I or II osteonecrosis of the femoral head, according to the grading system of the Association Research Circulation Osseous, were independently examined on two separate occasions by three observers of different specialty backgrounds and experience. Each observer used three methods to quantify the extent of osteonecrosis of the femoral head: (1) the index of necrotic extent, (2) the modified index of necrotic extent, and (3) the percentage of femoral head involvement. The interobserver and intraobserver agreement was determined for each method, and the ability of each method to predict the time to subchondral collapse was analyzed statistically.
Results:
There was significantly valid agreement among the observers for all three methods (p < 0.001 for all three). The correlation coefficients demonstrated substantial agreement among raters when they measured the index of necrotic extent and the percent involvement and nearly perfect agreement when they measured the modified index of necrotic extent. Survivorship analysis revealed that the percent involvement (p < 0.05), index of necrotic extent (p < 0.007), and modified index of necrotic extent (p < 0.04) were prognostically significant predictors of subchondral fracture.
Conclusions:
Our results indicate that the index of necrotic extent, modified index of necrotic extent, and estimation of the percentage of involvement of the femoral head are reproducible and reliable methods for quantitatively evaluating the extent of osteonecrosis of the femoral head. We believe that the three methods can be utilized with confidence. Furthermore, they are clinically useful for identifying hips at greatest risk for subchondral collapse.