Prediction of collapse in femoral head osteonecrosis: role of volumetric assessment

Risk Factors for Femoral Head Collapse in Osteonecrosis

BACKGROUND

Osteonecrosis of the femoral head (ONFH) affects at least 20,000 patients annually in the United States; however, the pathophysiology of disease progression is poorly understood. The purpose of this study was to determine the relative importance of three distinct elements and their relationship to the collapse of the femoral head as follows: (1) identifiable risk factors, (2) femoral head anatomy, and (3) the extent of the necrotic lesion.

METHODS

A single-center retrospective cohort study was performed on patients ≥ 18 year old who presented with ONFH. Ficat classification and femoral head anatomic parameters were measured on radiographs. Osteonecrotic lesion size was measured on magnetic resonance imaging using four validated methods. Multivariable regression analyses were performed to identify predictors of femoral head collapse.

RESULTS

There were 105 patients and 137 hips included in the final cohort, of which 50 (36.5%) had collapse of the femoral head. Multivariable analyses demonstrated that medical risk factors (adjusted odds ratio (aOR): 1.15), alcohol exposure (aOR: 1.23), and increased alpha angle (aOR: 4.51) were predictive of femoral head collapse. Increased femoral head offset (aOR: 0.54) was protective against collapse. An increased size of the osteonecrotic lesion was significantly predictive of collapse with all four measurement methods evaluated: three-dimensional volumetric (aOR: 3.73), modified Kerboul (aOR: 2.92), index of necrotic extent (aOR: 1.91), and modified index of necrotic extent (aOR: 2.05).

CONCLUSIONS

In an analysis of patients who had ONFH, we identified risk factors such as alcohol exposure, high alpha angle, increased lesion size, and decreased femoral offset as increasing the risk of femoral head collapse. Given the challenges of studying this patient population, large prospective studies of patients who have ONFH should seek to identify whether these factors are reliable indicators of femoral head collapse.

LEVEL OF EVIDENCE

III.

Panoramic heat map for spatial distribution of necrotic lesions

Aims

In this study, we aimed to visualize the spatial distribution characteristics of femoral head necrosis using a novel measurement method.

Methods

We retrospectively collected CT imaging data of 108 hips with non-traumatic osteonecrosis of the femoral head from 76 consecutive patients (mean age 34.3 years (SD 8.1), 56.58% male (n = 43)) in two clinical centres. The femoral head was divided into 288 standard units (based on the orientation of units within the femoral head, designated as N[Superior], S[Inferior], E[Anterior], and W[Posterior]) using a new measurement system called the longitude and latitude division system (LLDS). A computer-aided design (CAD) measurement tool was also developed to visualize the measurement of the spatial location of necrotic lesions in CT images. Two orthopaedic surgeons independently performed measurements, and the results were used to draw 2D and 3D heat maps of spatial distribution of necrotic lesions in the femoral head, and for statistical analysis.

Results

The results showed that the LLDS has high inter-rater reliability. As illustrated by the heat map, the distribution of Japanese Investigation Committee (JIC) classification type C necrotic lesions exhibited clustering characteristics, with the lesions being concentrated in the northern and eastern regions, forming a hot zone (90% probability) centred on the N4-N6E2, N3-N6E units of outer ring blocks. Statistical results showed that the distribution difference between type C2 and type C1 was most significant in the E1 and E2 units and, combined with the heat map, indicated that the spatial distribution differences at N3-N6E1 and N1-N3E2 units are crucial in understanding type C1 and C2 necrotic lesions.

Conclusion

The LLDS can be used to accurately measure the spatial location of necrotic lesions and display their distribution characteristics.

A nomogram for predicting the probability of femoral head collapse in convalescent SARS patients with glucocorticoid-induced osteonecrosis of the femoral head: an 18-year population-based retrospective cohort study

Background

This study aimed to develop a nomogram capable of predicting the probability of femoral head collapse based on an 18-year follow-up cohort of convalescent severe acute respiratory syndrome (SARS) patients with glucocorticoid-induced osteonecrosis of the femoral head (ONFH).

Methods

Data on the natural history of 120 patients (205 hips) who underwent glucocorticoid-induced ONFH at China-Japan Friendship Hospital (CJFH) in 2003 were retrospectively collected. Follow-up was conducted from June 2003 to October 2021. A nomogram was developed in a training cohort and validated in another cohort.

Results

A total of 205 hips were included for analysis, with 143 hips in the training cohorts and 62 hips in the validation cohorts. After 18 years of follow-up, 53 femoral heads collapsed, while 152 femoral heads spontaneously repaired to some extent (necrotic areas reduced or vanished). Following multivariate regression analysis, the Association Research Circulation Osseous (ARCO) staging, necrosis index (NI), and CJFH Classification were entered into the nomogram. The nomogram showed robust discrimination, with an AUC of 0.907 (95% CI: 0.85-0.96). The calibration curves showed an agreement between the probability as predicted by the nomogram and the actual probability. Application of the nomogram in the validation cohort also yielded good discrimination (AUC, 0.876, 95% CI: 0.7751-0.9761) and calibration.

Conclusion

The nomogram successfully predicted femoral head collapse in glucocorticoid-induced ONFH. With the nomogram, the prognosis for an individual patient with glucocorticoid-induced ONFH can be determined, which can lead to a rational therapeutic choice.

A Deep-Learning Model for Predicting the Efficacy of Non-vascularized Fibular Grafting Using Digital Radiography

RATIONALE AND OBJECTIVES

To develop a fully automated deep-learning (DL) model using digital radiography (DR) with relatively high accuracy for predicting the efficacy of non-vascularized fibular grafting (NVFG) and identifying suitable patients for this procedure.

MATERIALS AND METHODS

A retrospective analysis was conducted on osteonecrosis of femoral head patients who underwent NVFG between June 2009 and June 2021. All patients underwent standard preoperative anteroposterior (AP) and frog-lateral (FL) DR. Subsequently, the radiographs were pre-processed and labeled based on the follow-up results. The dataset was randomly divided into training and testing datasets. The DL-based prediction model was developed in the training dataset and its diagnostic performance was evaluated using the testing dataset.

RESULTS

A total of 339 patients with 432 hips were included in this study, with a hip preservation success rate of 71.52% as of June 2023. The hips were randomly divided into a training dataset (n = 324) and a testing dataset (n = 108). The ensemble model in predicting the efficacy of NVFG, reaching an accuracy of 78.9%, a precision of 78.7%, a recall of 96.0%, a F1-score of 86.5%, and an area under the curve (AUC) of 0.780. FL views (AUC, 0.71) exhibited better performance compared to AP views (AUC, 0.66).

CONCLUSION

The proposed DL model using DR enables automatic and efficient prediction of NVFG efficacy without additional clinical and financial burden. It can be seamlessly integrated into various clinical scenarios, serving as a practical tool to identify suitable patients for NVFG.

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.

Predictive value of clinical features and CT radiomics in the efficacy of hip preservation surgery with fibula allograft

BACKGROUND

Despite being an effective treatment for osteonecrosis of the femoral head (ONFH), hip preservation surgery with fibula allograft (HPS&FA) still experiences numerous failures. Developing a prediction model based on clinical and radiomics predictors holds promise for addressing this issue.

METHODS

This study included 112 ONFH patients who underwent HPS&FA and were randomly divided into training and validation cohorts. Clinical data were collected, and clinically significant predictors were identified using univariate and multivariate analyses to develop a clinical prediction model (CPM). Simultaneously, the least absolute shrinkage and selection operator method was employed to select optimal radiomics features from preoperative hip computed tomography images, forming a radiomics prediction model (RPM). Furthermore, to enhance prediction accuracy, a clinical-radiomics prediction model (CRPM) was constructed by integrating all predictors. The predictive performance of the models was evaluated using receiver operating characteristic curve (ROC), area under the curve (AUC), DeLong test, calibration curve, and decision curve analysis.

RESULTS

Age, Japanese Investigation Committee classification, postoperative use of glucocorticoids or alcohol, and non-weightbearing time were identified as clinical predictors. The AUC of the ROC curve for the CPM was 0.847 in the training cohort and 0.762 in the validation cohort. After incorporating radiomics features, the CRPM showed improved AUC values of 0.875 in the training cohort and 0.918 in the validation cohort. Decision curves demonstrated that the CRPM yielded greater medical benefit across most risk thresholds.

CONCLUSION

The CRPM serves as an efficient prediction model for assessing HPS&FA efficacy and holds potential as a personalized perioperative intervention tool to enhance HPS&FA success rates.

Experimental study of a 3D-printing technique combined with biphasic calcium phosphates to treat osteonecrosis of the femoral head in a canine model

OBJECTIVE

This study was aimed to use a digital design of 3D-printing technology to create a surgical navigation template. At the same time, biphasic calcium phosphate (BCP) was applied to treat osteonecrosis of the femoral head (ONFH) in animal models, based on accurate positioning of necrotic lesions in the navigation templates and observation of its therapeutic effect.

METHODS

Fifteen healthy adult male and female beagle dogs weighing 20 + 2 kg were randomly divided into three groups (n = 5) after establishing a model of ONFH using the liquid nitrogen freezing method. Each model underwent necrotic lesion creation and BPC implantations on one side of the femoral head and only necrotic lesion creation on the other side of the femoral head. Each group underwent CT examination, gross observation, histological examination and immunohistochemical staining at 6 weeks, 12 weeks and 18 weeks postoperatively.

RESULTS

At weeks 6, 12, and 18, CT and gross examination showed that the necrotic area in the experimental group was basically intact and had been completely raised by BCP material. In the control group, there were signs of bone repair in the femoral head, but there were still large bone defects and cavities. At week 18, extensive collapse of the cartilage surface was observed. Through histological examination, in the experimental group at 12 and 18 weeks, a large number of new and reconstructed bone trabeculae containing a large amount of collagen fibres were observed (P < 0.05), while in the control group, there was extensive necrosis of the bone trabeculae without cellular structural areas. Immunohistochemical examination observation: A large number of CD31-positive cells were observed in the experimental group at 6 weeks, gradually decreasing at 12 and 18 weeks (P < 0.05), while a small number of CD31-positive cells were observed in the control group at 18 weeks.

CONCLUSION

The 3D-printed navigation template can accurately locate ONFH lesions. Implantation of BCP material can effectively play a supporting role, prevent the collapse of the loading surface, and induce bone formation and angiogenesis to some extent.

Prognosis and risk prediction of bone impaction grafting through femoral head-neck fenestration: a retrospective cohort study

The bone impaction grafting through femoral head-neck fenestration was a favorable hip preservation procedure but without prognosis estimation. This study retrospectively reviewed 79 patients' clinical data (114 hips) with osteonecrosis of the femoral head (ONFH) who underwent this procedure from June 2009 to June 2019. By the end of June 2022, the median survival time of the hip was (74.13 ± 44.88) months, and the success rate of hip preservation was 68.42%. Lateral reserved angle (LPA) and combined reserved angle (CPA) had statistically significant differences (P < 0.001) both in univariate analysis and a multivariate logistic regression model. The multivariate logistic regression model of area under curve (AUC) area of the receiver operating characteristic (ROC) curve was 0.931(sensitivity = 95.00%, specificity = 88.40%, log-rank test: P < 0.01), and the calibration curve indicated good prediction accuracy. The ROC analysis and Cox proportional hazards regression model revealed that the cutoff point of LPA was 50.95° (sensitivity = 95.00%, specificity = 72.09%, log-rank test: P < 0.05) and the cutoff point of CPA was 90.51° (sensitivity = 90.00%, specificity = 90.70%, log-rank test: P < 0.05). A nomogram plot to predict the risk of failure (C-index = 0.873, 95% CI: 0.785 to 0.961) and nomograms for predicting the survival probability at 1, 2 or 3 years whose calibration curves showed excellent prediction accuracy were available for the clinician. Preserved angles (PAs) are valuable in the prediction of prognosis in surgical treatment. The bone impaction grafting through femoral head-neck fenestration can achieve better clinical efficacy, especially for patients with LPA >50.95° and CPA >90.51°.

Evaluation of the predictive values of collapse and necrotic lesion boundary for osteonecrosis of the femoral head prognosis

OBJECTIVE

Osteonecrosis of the femoral head (ONFH) is a disabling and intractable orthopedic disease largely affecting young and middle-aged groups. Current standard of treatment relies on the collapse of femoral head as a predictor for prognosis. However, a wide range of variability in repair potentials is observed in patients with femoral head collapse. Therefore, the present study aimed to evaluate the accuracy of femoral head collapse as a predictor and to propose the necrotic lesion boundary as a novel yet reliable measure for ONFH prognosis.

METHODS

A retrospective cross-sectional study was conducted at the First Affiliated Hospital of Guangzhou University of Chinese Medicine, 203 hips with ONFH from 134 patients were included. The occurrences and progression of femoral head collapse were recorded. Necrosis lesion boundary was quantified and classified for each case based on anteroposterior view intact ratio (APIR) and the frog-leg view intact ratio (FLIR) as independent variables. Dependent variables were defined as progressive collapse or terminal collapse for Association Research Circulation Osseous (ARCO) stage II and III respectively. Logistic regression analysis, Receiver Operating Characteristic (ROC) curve and Kaplan-Meier (K-M) survival analysis was performed and results were interpreted.

RESULTS

Out of the 106 hips in ARCO stage II, 31 hips collapsed with further progression, while 75 hips had no collapse or collapse with repair of the necrotic areas. Out of the 97 hips in ARCO stage IIIA, the collapse continued to progress in 58 hips while the necrotic areas were repaired in 39 hips. Logistic regression analysis demonstrated that both APIR and FLIR, were independent risk factors. Further ROC curve analysis indicated that the cutoff values of APIR and FLIR could be considered as indications for evaluating the prognosis of ONFH. Contrary to the traditional view of poor prognosis after femoral head collapse, K-M survival analysis demonstrated a high value of APIR and FLIR for ONFH prognosis.

CONCLUSION

The present study found that the occurrence of collapse is an oversimplified predictor for ONFH prognosis. The collapse of the femoral head in ONFH does not predict a poor prognosis. The necrosis lesion boundary has a high value in predicting ONFH prognosis and informing clinical treatment strategies.

Volume and location of bone regeneration after autologous expanded mesenchymal stromal cells in hip osteonecrosis : a pilot study

AIMS

Successful cell therapy in hip osteonecrosis (ON) may help to avoid ON progression or total hip arthroplasty (THA), but the achieved bone regeneration is unclear. The aim of this study was to evaluate amount and location of bone regeneration obtained after surgical injection of expanded autologous mesenchymal stromal cells from the bone marrow (BM-hMSCs).

METHODS

A total of 20 patients with small and medium-size symptomatic stage II femoral head ON treated with 140 million BM-hMSCs through percutaneous forage in the EudraCT 2012-002010-39 clinical trial were retrospectively evaluated through preoperative and postoperative (three and 12 months) MRI. Then, 3D reconstruction of the original lesion and the observed postoperative residual damage after bone regeneration were analyzed and compared per group based on treatment efficacy.

RESULTS

The mean preoperative lesion volume was 18.7% (SD 10.2%) of the femoral head. This reduced to 11.6% (SD 7.5%) after three months (p = 0.015) and 3.7% (SD 3%) after one year (p < 0.001). Bone regeneration in healed cases represented a mean 81.2% (SD 13.8%) of the initial lesion volume at one year. Non-healed cases (n = 1 stage progression; n = 3 THAs) still showed bone regeneration but this did not effectively decrease the ON volume. A lesion size under mean 10% (SD 6%) of the femoral head at three months predicted no ON stage progression at one year. Regeneration in the lateral femoral head (C2 under Japanese Investigation Committee (JCI) classification) and in the central and posterior regions of the head was predominant in cases without ON progression.

CONCLUSION

Bone regeneration was observed in osteonecrotic femoral heads three months after expanded autologous BM-hMSC injection, and the volume and location of regeneration indicated the success of the therapy.Cite this article: Bone Joint Res 2022;11(12):881-889.

The Role of Structural Deterioration and Biomechanical Changes of the Necrotic Lesion in Collapse Mechanism of Osteonecrosis of the Femoral Head

Osteonecrosis of the femoral head (ONFH) is a crippling disease which is due to a lack of effective therapeutic measures. Its natural progression is rapid, the internal bone structure of the femoral head changes dramatically, and the subsequent fractures and collapse cause severe hip pain and loss of hip function. Femoral head collapse is a critical turning point in the development of ONFH and is related to the prognosis of patients. Early prevention and intervention help to preserve the hip joint and delay femoral head collapse. However, the mechanism of collapse still needs to be further studied because it is affected by different complex factors. This review discusses the underlying causes of femoral head collapse from two aspects: structural degradation and regional changes of biomechanical properties in the necrotic femoral head.

Concentric Circle Technique for Assessment of Femoral Head Deficiency in Osteonecrosis of Femoral Head

Introduction

There is a lack of standardized objective tools to assess collapse for osteonecrosis of the femoral head (ONFH) patients’ follow-up. We describe a quantitative technique of collapse assessment using a superimposed concentric circular ring matching the intact part of the femoral head in anteroposterior (AP) radiographs.

Methods

We retrospectively analyzed 30 normal femoral heads and 30 ONFH (15 pre-collapse,15 post-collapse) in anteroposterior hip radiographs. A best-fitting circle was superimposed on articular margins of the femoral head and the maximum width of the deficient zone of the femoral head (not matching the circle) was measured. The width (pW) was measured as percentage-width in proportion to the circle’s diameter. The findings were compared among normal and ONFH radiographs. Intraclass correlation coefficients were calculated for intraobserver and interobserver reliability of the measurements.

Results

The mean femoral head deficiencies predicted by pW were 0.2±0.5% for normal hip, 2.8±1.1% for pre-collapse, and 8.9±3.8% for post-collapse radiographs. We observed significant differences in the measurements of pW among the control group, pre-collapse and post-collapse groups. Interobserver and intraobserver reliabilities for the measurements were high.

Conclusion

The described concentric circle technique is a simple and reliable method for objective assessment of subtle alterations in the sphericity of the femoral head and can be helpful for the radiographic follow-up of ONFH patients.