Effects of the location of both anterior and lateral boundaries of the necrotic lesion on collapse progression in osteonecrosis of the femoral head

X-ray based radiomics machine learning models for predicting collapse of early-stage osteonecrosis of femoral head

This study aimed to develop an X-ray radiomics model for predicting collapse of early-stage osteonecrosis of the femoral head (ONFH). A total of 87 patients (111 hips; training set: n = 67, test set: n = 44) with non-traumatic ONFH at Association Research Circulation Osseous (ARCO) stage II were retrospectively enrolled. Following data dimensionality reduction and feature selection, radiomics models were constructed based on anteroposterior (AP), frog-lateral (FL), and AP + FL combined view using random forest (RF), support vector machine (SVM), and stochastic gradient descent (SGD). After the optimal radiomics model was selected based on areas under the curve (AUC), its performance on the test set was compared with that of orthopaedists using receiver operating characteristic (ROC) curves and confusion matrices. Among all radiomics models, the SVM-based AP + FL combined view model (AP + FL-Rad_SVM) achieved the highest individual performance demonstrating an AUC of 0.904 (95% CI 0.829 -0.978) in the test set, which was significantly better than that of three attending surgeons (p = 0.014, 0.004, and 0.045, respectively). The SVM model based on AP + FL views of hip X-ray exhibited excellent ability in predicting the collapse of ONFH and showed superior performance compared with less experienced orthopaedic surgeons. This model may inform clinical decision-making for early-stage ONFH.

Relationship between anterior or posterior femoral head necrosis and collapse based on MRI-defined key necrotic layer sets

BACKGROUND

Current clinical studies on femoral head necrotic lesions primarily focus on the medial and lateral regions, while detailed MRI-based methods to evaluate the relationship between anterior or posterior necrosis and collapse remain lacking.

OBJECTIVE

By defining the anterior and posterior positions of the femoral head in MRI, a method was proposed for rapid clinical prognosis assessment of femoral head necrosis based on necrotic location.

METOHD

A retrospective analysis was conducted on TSE sequence T1W1 coronal plane images from 200 cases of femoral head necrosis. The frequency of necrotic lesions appearing on each MRI layer was statistically analyzed to construct a high-frequency necrotic layer set. Among these cases, 100 hips were randomly selected, and the relationship between femoral head collapse at one-year follow-up and different high-frequency necrotic layer sets was analyzed to identify the key necrotic layer set. Based on this, the anterior and posterior regions of the femoral head were defined on MRI. The remaining 100 hips were used as a validation set to assess the impact of anterior or posterior necrosis of the femoral head, as defined by this method, on collapse.

RESULTS

In this study, a total of eight high-frequency necrotic lesion layer sets (S1-S8) were constructed based on MRI data. Among them, S3 (L1 + L2 + L0 + L3) showed the strongest correlation with femoral head collapse, with an AUC of 0.662. Therefore, S3 was defined as the anterior side of the femoral head. Analysis of the validation set revealed that, using this method, the probability of femoral head collapse was 11.4 times higher when necrotic lesions appeared on the anterior side compared to the absence of necrosis on the anterior side.

CONCLUSION

In MRI, the anterior side of the femoral head corresponds to the S3 region, where necrosis increases the risk of collapse by 11.4 times.

Can necrotic depth be a substitute of necrotic volume to predict collapse progression in osteonecrosis of the femoral head?

OBJECTIVE

Although some patients may experience collapse progression while others may not in post-collapse osteonecrosis of the femoral head (ONFH) with a necrotic lesion located within the weight-bearing part of the acetabulum (Type B/C1), few studies have focused on the natural course after collapse. This study aimed to clarify the correlation between necrotic volume (NV) and necrotic depth (ND) in predicting collapse progression in patients with post-collapse ONFH Type B/C1.

MATERIALS AND METHODS

We retrospectively reviewed 54 hips with post-collapse ONFH Type B/C1 from 52 consecutive patients who were conservatively followed up for more than 1 year. We measured the amount of femoral head collapse using biplane radiographs at each follow-up period, and produced Kaplan-Meier survival curves with collapse progression (≥ 1 mm) as the endpoint. We compared NV and ND, which were calculated as the ratio of the distance from the articular surface of the femoral head to the deepest point of a necrotic lesion to the femoral head diameter in the mid-coronal slice of T1-weighted magnetic resonance imaging (MRI).

RESULTS

We observed collapse progression in 31 hips (57.4%). The NV and ND were significantly greater in hips with collapse progression than in those without collapse progression (p = 0.0127 and 0.0047, respectively). Necrotic volume was significantly correlated with ND　(rs = 0.56, p < 0.0001).

CONCLUSION

This study suggests that necrotic depth on the mid-coronal slice of T1-weighted MRI can be a substitute for necrotic volume to predict collapse progression in ONFH Type B/C1.

Factors related to collapse progression in Japanese Investigation Committee classification type B osteonecrosis of the femoral head

PURPOSE

This study aimed to identify factors related to collapse progression in Japanese Investigation Committee classification type B osteonecrosis of the femoral head (ONFH) and to identify patients who would benefit from surgical treatment.

METHODS

This study included 41 patients (56 hips) with type B ONFH with a minimum follow-up of three years. Based on a ≥ 3 mm collapse progression in ONFH, we categorised patients into two groups: collapse progression and no collapse progression. Sagittal and coronal computed tomography images were used to measure the necrotic region relative to the intact femoral head diameter. The ratios of the necrotic regions of transverse and vertical diameter in coronal and sagittal images are defined as mediolateral transverse and mediolateral vertical, anteroposterior transverse and anteroposterior vertical, respectively. Demographic data and these imaging findings were compared between the two groups. We established a cut-off value for predicting collapse progression through receiver operating characteristic analysis and determined survival rates.

RESULTS

Type B ONFH had a 17.8% collapse progression rate. The mediolateral transverse, mediolateral vertical, anteroposterior transverse, and anteroposterior vertical were significantly higher in the collapse progression group (P < 0.01). Mediolateral transverse was an independent risk factor of collapse progression (hazard ratio, 1.27; 95% confidence interval, 1.03-1.57; P = 0.03), with an optimal cut-off of 45.6%. The 5-year survival rates with collapse progression as the endpoints were 57.0 and 94.9% in the mediolateral transverse of ≥ 45.6 and < 45.6%, respectively.

CONCLUSION

A mediolateral transverse of ≥ 45.6% predicts collapse progression in patients with type B ONFH.

Residual deformity after femoral neck fracture affects the location of osteonecrosis of the femoral head

Aims

The localization of necrotic areas has been reported to impact the prognosis and treatment strategy for osteonecrosis of the femoral head (ONFH). Anteroposterior localization of the necrotic area after a femoral neck fracture (FNF) has not been properly investigated. We hypothesize that the change of the weight loading direction on the femoral head due to residual posterior tilt caused by malunited FNF may affect the location of ONFH. We investigate the relationship between the posterior tilt angle (PTA) and anteroposterior localization of osteonecrosis using lateral hip radiographs.

Methods

Patients aged younger than 55 years diagnosed with ONFH after FNF were retrospectively reviewed. Overall, 65 hips (38 males and 27 females; mean age 32.6 years (SD 12.2)) met the inclusion criteria. Patients with stage 1 or 4 ONFH, as per the Association Research Circulation Osseous classification, were excluded. The ratios of anterior and posterior viable areas and necrotic areas of the femoral head to the articular surface were calculated by setting the femoral head centre as the reference point. The PTA was measured using Palm's method. The association between the PTA and viable or necrotic areas of the femoral head was assessed using Spearman's rank correlation analysis (median PTA 6.0° (interquartile range 3 to 11.5)).

Results

We identified a negative correlation between PTA and anterior viable areas (rho -0.477; p = 0.001), and no correlation between PTA and necrotic (rho 0.229; p = 0.067) or posterior viable areas (rho 0.204; p = 0.132).

Conclusion

Our results suggest that residual posterior tilt after FNF could affect the anteroposterior localization of necrosis.

Analysis of the natural collapse course of non-traumatic osteonecrosis of the femoral head based on the matrix model

BACKGROUND

There are many predictions about the progression of natural collapse course of osteonecrosis of the femoral head. Here, we aimed to combine the three classical prediction methods to explore the progression of the natural collapse course.

METHODS

This retrospective study included 127 patients admitted to our hospital from October 2016 to October 2017, in whom the femoral head had not collapsed. Logistic regression analysis was performed to determine the collapse risk factors, and Kaplan-Meier survival curves were used for femoral head survival analysis. The collapse rate of the femoral head was recorded within 5 years based on the matrix model. The specificity of the matrix model was analyzed using the receiver operating characteristic curve.

RESULTS

A total of 127 patients with a total of 202 hips were included in this study, and 98 hips collapsed during the follow-up period. Multivariate logistics regression analysis showed that the predictive ability of the matrix model was stronger than Association Research Circulation Osseous staging, Japanese Investigation Committee classification, and area (P < 0.05). Kaplan-Meier survival curve showed that the median survival time of femoral head in patients was 3 years. The result of the receiver operating characteristic curve analysis showed that the area under the curve (AUC) of the matrix model had better predictive value (AUC = 0.771, log-rank test: P < 0.001).

CONCLUSION

We creatively combined the three classical prediction methods for evaluating the progression of the natural collapse course based on the matrix model and found that the higher the score of the matrix model, the higher the femoral head collapse rate. Specifically, the matrix model has a potential value in predicting femoral head collapse and guiding treatment selection.