Micro Perfusion and Quantitative Analysis of the Femoral Head Intraosseous Artery

Research progress in the pathogenesis of hormone-induced femoral head necrosis based on microvessels: a systematic review

Hormonal necrosis of the femoral head is caused by long-term use of glucocorticoids and other causes of abnormal bone metabolism, lipid metabolism imbalance and blood microcirculation disorders in the femoral head, resulting in bone trabecular fracture, bone tissue necrosis collapse, and hip dysfunction. It is the most common type of non-traumatic necrosis of the femoral head, and its pathogenesis is complex, while impaired blood circulation is considered to be the key to its occurrence. There are a large number of microvessels in the femoral head, among which H-type vessels play a decisive role in the "angiogenesis and osteogenesis coupling", and thus have an important impact on the occurrence and development of femoral head necrosis. Glucocorticoids can cause blood flow injury of the femoral head mainly through coagulation dysfunction, endothelial dysfunction and impaired angiogenesis. Glucocorticoids may inhibit the formation of H-type vessels by reducing the expression of HIF-1α, PDGF-BB, VGEF and other factors, thus causing damage to the "angiogenesis-osteogenesis coupling" and reducing the ability of necrosis reconstruction and repair of the femoral head. Leads to the occurrence of hormonal femoral head necrosis. Therefore, this paper reviewed the progress in the study of the mechanism of hormone-induced femoral head necrosis based on microvascular blood flow at home and abroad, hoping to provide new ideas for the study of the mechanism of femoral head necrosis and provide references for clinical treatment of femoral head necrosis.

Method for reconstructing femoral head blood supply by anastomosing the intraosseous artery

Background

The reconstruction of femoral head blood supply is crucial in the management of avascular necrosis and related conditions. This study presents a method for reconstructing the femoral head blood supply by anastomosing the intraosseous artery.

Methods

The femoral heads of six male Landrace swine were surgically exposed, and subcranial fractures of the femoral neck were intentionally created. Under microscopic guidance, the trophoblastic foramen of the posterior supporting artery was identified. Subsequently, a triangular bone window was carefully crafted to expose the intraosseous artery. Following the fixation of the femoral head, an anastomosis was performed between the intraosseous artery and the posterior inferior supporting artery located at the distal end of the fracture. The assessment of femoral head blood supply was conducted using Kirschner's pinhole and angiography techniques.

Results

The anastomotic intraosseous artery exhibited a vibrant red color, indicating adequate blood perfusion, and demonstrated pulsatile flow. Observation through pinholes in the surface of the femoral head revealed continuous blood flow. Angiography further confirmed the successful circulation, as the contrast agent entered the inferior retinacular artery branch originating from the deep femoral artery. The contrast agent then proceeded to enter the femoral head through the retinacular artery, reaching the anastomosis site of the intraosseous artery. Notably, the angiography also revealed the presence of visible internal branches, highlighting the establishment of a functional vascular network.

Discussion

The method of reconstructing the blood supply to the femoral head through anastomosis of the intraosseous artery enables utilization of the existing blood supply system within the femoral head. This study is just a preliminary study of this innovative technique that has the potential to prevent and/or treat femoral head necrosis following a femoral neck fracture. By restoring adequate blood flow to the affected area, this approach holds promise in preserving the viability and functionality of the femoral head, ultimately improving patient outcomes.

Methods to predict osteonecrosis of femoral head after femoral neck fracture: a systematic review of the literature

BACKGROUND

Femoral neck fracture (FNF) is a very common traumatic disorder and a major cause of blood supply disruption to the femoral head, which may lead to a severe long-term complication, osteonecrosis of femoral head (ONFH). Early prediction and evaluation of ONFH after FNF could facilitate early treatment and may prevent or reverse the development of ONFH. In this review paper, we will review all the prediction methods reported in the previous literature.

METHODS

Studies on the prediction of ONFH after FNF were included in PubMed and MEDLINE databases with articles published before October 2022. Further screening criteria were conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. This study highlights all the advantages and disadvantages of the prediction methods.

RESULTS

There were a total of 36 studies included, involving 11 methods to predict ONFH after FNF. Among radiographic imaging, superselective angiography could directly visualize the blood supply of the femoral head, but it is an invasive examination. As noninvasive detection methods, dynamic enhanced magnetic resonance imaging (MRI) and SPECT/CT are easy to operate, have a high sensitivity, and increase specificity. Though still at the early stage of development in clinical studies, micro-CT is a method of highly accurate quantification that can visualize femoral head intraosseous arteries. The prediction model relates to artificial intelligence and is easy to operate, but there is no consensus on the risk factors of ONFH. For the intraoperative methods, most of them are single studies and lack clinical evidence.

CONCLUSION

After reviewing all the prediction methods, we recommend using dynamic enhanced MRI or single photon emission computed tomography/computed tomography in combination with the intraoperative observation of bleeding from the holes of proximal cannulated screws to predict ONFH after FNF. Moreover, micro-CT is a promising imaging technique in clinical practice.

Comparing the volume of vascular intersection of two femoral neck fracture fixation implants using an In silico technique

Femoral neck fracture displacement with subsequent vascular disruption is one of the factors that contribute to trauma-induced avascular necrosis of the femoral head. Iatrogenic damage of the intraosseous arterial system during fixation of femoral neck fracture is another possible cause of avascular necrosis that is less well understood. Recently, Zhao et al (2017) reconstructed 3D structures of intraosseous blood supply and identified the epiphyseal and inferior retinacular arterial system to be important structures for maintaining the femoral head blood supply after femoral neck fracture. The authors therefore recommended placing implants centrally to reduce iatrogenic vascular injuries. Our in vitro study compared the spatial footprint of a traditional dynamic hip screw with an antirotation screw versus a newly developed hip screw with an integrated antirotation screw on intraosseous vasculature.

Methods

Three dimensional (3D) µCT angiograms of 9 cadaveric proximal femora were produced. Three segmented volumes-porous or cancellous bone, filled or cortical bone, and intraosseous vasculature-were converted to surface files. 3D in silico models of the fixation systems were sized and implanted in silico without visibility of the vascular maps. The volume of vasculature that overlapped with the devices was determined. The ratio of the vascular intersection to the comparator device was calculated, and the mean ratio was determined. A paired design, noninferiority test was used to compare the devices.

Results

Results indicate both significant (P < 0.001) superiority and noninferiority of the hip screw with an integrated antirotation screw when compared with a dynamic hip screw and antirotation screw for the volume of vasculature that overlapped with each device in the femoral neck.

Conclusions

Combining established methods of vascular visualization with newer methods enables an implant's impact on vascular intersection to be assessed in silico. This methodology suggests that when used for femoral neck fracture management, the new device intersects fewer blood vessels than the comparator. Comparative clinical studies are needed to investigate whether these findings correlate with the incidence of avascular necrosis and clinical outcomes.

Detection of Subchondral Bone Microcirculatory Perfusion in Adults with Early Osteonecrosis of the Femoral Head Using Contrast-Enhanced Ultrasound: A Prospective Study

The aim of this study was to quantitatively assess subchondral bone microcirculation perfusion in adults with early osteonecrosis of the femoral head (ONFH) using contrast-enhanced ultrasound (CEUS) and to evaluate its correlation with the Association Research Circulation Osseous (ARCO) stage. We investigated 97 adult patients with definite ONFH by imaging a total of 155 hips, performing CEUS, storing images of CEUS processes at different ARCO stages and generating CEUS time-intensity curves (TICs) to obtain perfusion parameters. Differences in CEUS parameters at different ARCO stages were analyzed, and correlations were explored. A logistic regression model was constructed by incorporating the meaningful CEUS indicators. The CEUS parameters time to peak (TTP), peak intensity (PI), enhanced intensity (EI), ascending slope (AS), descending slope (DS) and area under the receiver operating characteristic curve (AUC) were significantly different in ARCO stage Ⅰ compared with stage ⅢA, and the same results were obtained in stage Ⅱ compared with stage ⅢA. However, there were no significant differences between stages Ⅰ and Ⅱ. The MTT (mean transit time) assay was not significantly different between the different stages. The receiver operating characteristic curve analysis of TTP, PI, EI, AS, DS and AUC in stages Ⅰ and ⅢA had a certain diagnostic efficacy, similar to the results in stages Ⅱ and ⅢA. The diagnostic performance of DS was less accurate in stages Ⅰ and ⅢA, while the diagnostic performance of TTP was less accurate in stages Ⅱ and ⅢA. ARCO stage was independently and negatively correlated with TTP and DS and independently and positively correlated with PI, EI, AS and AUC. The MTT assay was not correlated with ARCO stage. Logistic regression models containing statistically significant TTP, EI and AUC values were constructed, and all three values were closely related to the ARCO stage. In patients with different ARCO stages of ONFH, CEUS can effectively assess subchondral bone perfusion of the femoral head and is expected to become an effective imaging method for the diagnosis of early ONFH.

A modified surgical method for the treatment of ONFH: quadratus femoris muscle pedicle bone grafting with preservation of the posterior superior retinacular artery

BACKGROUND

Osteonecrosis of the femoral head (ONFH) can lead to pain and loss of function of the hip joint, which places a great burden on patients and society. Surgery is the main treatment for osteonecrosis of the femoral head, and quadratus femoris muscle pedicle bone grafting has a definite therapeutic effect as one method of surgery for the treatment of ONFH. However, the posterior superior retinacular artery is often injured during quadratus femoris muscle pedicle bone graft surgery. There is evidence that this artery is extremely important to the femoral head, as injury to this artery will seriously affect the blood supply of the femoral head. Therefore, this situation restricts the clinical application of quadratus femoris muscle pedicle bone grafts. We aimed to explore a new surgical method of quadratus femoris muscle pedicle bone grafting that can preserve the integrity of the posterior superior retinacular artery.

METHODS

We modified the traditional quadratus femoris muscle pedicle bone graft and preserved the integrity of the posterior superior retinacular artery. To explore the safety and feasibility of the operation, we simulated the operation on 6 fresh frozen cadavers (12 hips) and measured the related data. We also tried this modified surgical method in the clinic and collected detailed data from the patients.

RESULTS

By simulating the modified quadratus femoris muscle pedicle bone graft on the hip joints of fresh frozen cadavers, we found that the posterior superior retinacular artery existed in all cadaver specimens and that the sources may be different (MFCA or IGA). In the modified operation, the joint capsule did not need to be cut during the operation; therefore, the integrity of the posterior superior retinacular artery was preserved. The quadratus femoris muscle was exposed via the posterior approach of the hip joint, and then the quadratus femoris muscle pedicle bone flap was chiseled. After the pedicle of the quadratus femoris muscle was loosened properly, the migration distance of the quadratus femoris muscle pedicle bone flap reached 5.89 ± 0.45 (χ ± s) cm. The bone flap was trimmed properly and placed on one side. Next, we drilled a bone tunnel from the external intertrochanteric aspect of the capsule of the hip joint, and the bone tunnel broke through the sclerosing zone and proceeded straight to the necrotic area of the femoral head. Next, the necrotic bone was removed with a ring saw and arc bone knife, autogenous bone or allogeneic bone was filled into the bone groove according to the situation, and the cancellous bone in the bone groove was tamped by percussion. Then, the bone flap was inserted into the bone groove, and appropriate pressurization was performed. The depth of the bone groove was determined by the location of ONFH. We found that the furthest distance between the bone groove and the femoral head was 4.76 ± 0.07 (χ ± s) cm and that the length of the bone flap was (4.91 ± 0.23) (χ ± s) cm. This means that when the depth of the bone groove reached the area of ONFH, the quadratus femoris muscle pedicle bone flap had a sufficient length and migration distance to be embedded in the area of ONFH and firmly fixed, and the quadratus femoris did not have much tension. The closest distance between the posterior superior retinacular artery and the bone groove was (1.11 ± 0.96) (χ ± s) cm. When the bone groove was created in this area, the edge of the bone groove had a safe distance of at least 1 cm from the posterior superior retinacular artery of the femoral head. We attempted to implement this modified operation clinically. During the procedure, the quadratus femoris muscle pedicle bone flap was embedded into the drilled bone groove and fixed with a magnesium nail. There was no sliding of the bone flap after the operation, and the posterior superior retinacular artery was intact. We followed the patient for 3 months and found that the patient recovered well with no weight-bearing by the affected limb. The duration of the modified operation was shorter than that of the traditional quadratus femoris muscle pedicle bone graft, the amount of bleeding was significantly reduced, the postoperative pain was lessened, and no special discomfort was reported. Postoperative imaging examination showed that the collapse of the femoral head had been partially corrected and that the bone flap had gradually fused with the surrounding bone.

CONCLUSIONS

Through this experimental study, we confirmed the feasibility of the modified method for quadratus femoris muscle pedicle bone grafting with preservation of the posterior superior retinacular artery. This modified operation not only retains the integrity of the posterior superior retinacular artery of the femoral head but also reduces the difficulty of the operation and shortens the surgical time, which is of great clinical significance.

A Method to Visualize and Quantify the Intraosseous Arteries of the Femoral Head by Vascular Corrosion Casting

OBJECTIVE

To describe a method to display the three-dimensional distribution of intraosseous arteries in the femoral head by vascular corrosion casting.

METHODS

An experimental study was done to expose the intraosseous arteries of the femoral head by a microperfusion corrosion method between January 2021 and May 2021. Specimens were 23 swine femoral heads (12 female specimens and 11 male specimens, where age of swine ranged from 8 to 12 months, and the weight was approximately 150 kg). The femoral heads were microperfused with the vascular casting resin through retinacular arteries, and the bone of the femoral head was dissolved with 50% sodium hydroxide and 10% hydrochloric acid and rinsed under the microscope until the vessel casts were completely exposed. The distribution and anastomosis of the arteries in the femoral head were observed under direct vision and microscopy. The diameter of the artery in the femoral head was measured at 0.5 cm after its entry into the bone of the femoral head with a microscale under the microscope. The number of internal arteries with diameter ≥0.05 mm was counted. The number and diameter of the main trunk of the epiphyseal arteries in the femoral head between male and female swine were compared.

RESULTS

The vascular casting specimen of the swine femoral head was successfully produced by using epoxy resin as a casting agent, and the three-dimensional intraosseous vascular structures were clearly visible. The number of epiphyseal arteries in male and female swine was 8.55 ± 2.15 and 8.83 ± 2.15 (t = -0.31, p = 0.38), respectively. The diameters of the superior epiphyseal arteries in male and female swine were 0.35 ± 0.09 and 0.31 ± 0.08 mm (t = 1.03, p = 0.16), the diameters of the inferior epiphyseal arteries were 0.47 ± 0.05 and 0.49 ± 0.09 mm (t = -0.57, p = 0.29), and the diameters of the anterior epiphyseal arteries were 0.34 ± 0.08 and 0.33 ± 0.13 mm (t = 0.32, p = 0.37). There was no significant difference in the number and diameter of the main trunk of intraosseous arteries between male and female swine (p > 0.05). The main trunk of intraosseous arteries formed an anastomosis in the center of the femoral head. Among 23 swine femoral head samples, three types of intraosseous anastomosis were observed, including 13 (57%) posterior superior-posterior inferior, seven (30%) posterior inferior-anterior, and three (13%) uniform intraosseous anastomosis.

CONCLUSION

The microperfusion corrosion method can produce the vascular casting specimen of swine femoral head revealing the three-dimensional structure of the intraosseous artery, which clearly shows the origin, course and branches, and diameter, as well as the anastomosis, of nutrient arteries in the femoral head. This method provides a simple and rapid technique for quantifying and visualizing intraosseous arteries.

Relationship Between Blood Flow and Collapse of Nontraumatic Osteonecrosis of the Femoral Head

BACKGROUND

To investigate the collapse mechanism in osteonecrosis of the femoral head (ONFH), we studied the relationship between the femoral head (FH) blood circulation changes and the collapse area histomorphometry characteristics.

METHODS

A technique involving microvascular perfusion of the FH in vitro to reconstruct the vessels in the FH at different stages of nontraumatic ONFH (40 cases). In addition, we also examined the histomorphometry characteristics in the collapse area during ONFH at different stages using the hard tissue section technique. To investigate the blood supply changes in the FH on pathological involved in the FH collapse process.

RESULTS

The results showed that in all FHs, the collapse area always involved the margin of the necrotic lesion of the lateral column. Histologically, the fracture occurred between the thickened and necrotic trabeculae at the junction. We found that the collapse started at the lateral column of the FH in the necrotic lesion and that the lateral column was ischemic, which caused the FH to begin to collapse.

CONCLUSIONS

Based on the above findings, the relationship between associations of the blood circulation to the collapse showed that if a portion of the blood supply of the lateral column (the superior retinacular artery) was preserved, the prognosis of the natural progression of the diseases was improved, the collapse rate was low and collapse occurred later. The blood circulation of artery in the lateral column was good, and the FH maintained an intact shape even if the internal region was ischemic. Therefore, we can predict the collapse of the FH by measuring the blood flow in the lateral area of the FH, thus providing guidance for the selection of FH-preserving clinical therapy in young and middle-aged patients.

CLINICAL RELEVANCE

This work provides a proof of how to predict the collapse of the FH by measuring the blood flow, providing guidance for FH-preserving clinical therapy in young and middle-aged patients.

Microstructure Analysis and Reconstruction of a Meniscus

OBJECTIVE

To analyze the characteristics of menicus microstructure and to reconstruct a microstructure-mimicing 3D model of the menicus.

METHODS

Human and sheep meniscus were collected and prepared for this study. Hematoxylin-eosin staining (HE) and Masson staining were conducted for histological analysis of the meniscus. For submicroscopic structure analysis, the meniscus was first freeze-dried and then scanned by scanning electron microscopy (SEM). The porosity of the meniscus was determined according to SEM images. A micro-MRI was used to scan each meniscus, immersed in distilled water, and a 3D digital model was reconstructed afterwards. A three-dimensional (3D) resin model was printed out based on the digital model. Before high-resolution micro-CT scanning, each meniscus was freeze-dried. Then, micro-scale two-dimensional (2D) CT projection images were obtained. The porosity of the meniscus was calculated according to micro-CT images. With micro-CT, multiple 2D projection images were collected. A 3D digital model based on 2D CT pictures was also reconstructed. The 3D digital model was exported as STL format. A 3D resin model was printed by 3D printer based on the 3D digital model.

RESULTS

As revealed in the HE and Masson images, a meniscus is mostly composed of collagen, with a few cells disseminated between the collagen fiber bundles at the micro-scale. The SEM image clearly shows the path of highly cross-linked collagen fibers, and massive pores exist between the fibers. According to the SEM images, the porosity of the meniscus was 34.1% (34.1% ± 0.032%) and the diameters of the collagen fibers were varied. In addition, the cross-linking pattern of the fibers was irregular. The scanning accuracy of micro-MRI was 50 μm. The micro-MRI demonstrated the outline of the meniscus, but the microstructure was obscure. The micro-CT clearly displayed microfibers in the meniscus with a voxel size of 11.4 μm. The surface layer, lamellar layer, circumferential fibers, and radial fibers could be identified. The mean porosity of the meniscus according to micro-CT images was 33.92% (33.92% ± 0.03%). Moreover, a 3D model of the microstructure based on the micro-CT images was built. The microscale fibers could be displayed in the micro-CT image and the reconstructed 3D digital model. In addition, a 3D resin model was printed out based on the 3D digital model.

CONCLUSION

It is extremely difficult to artificially simulate the microstructure of the meniscus because of the irregularity of the diameter and cross-linking pattern of fibers. The micro-MRI images failed to demonstrate the meniscus microstructure. Freeze-drying and micro-CT scanning are effective methods for 3D microstructure reconstruction of the meniscus, which is an important step towards mechanically functional 3D-printed meniscus grafts.

Traditional and bionic dynamic hip screw fixation for the treatment of intertrochanteric fracture: a finite element analysis

PURPOSE

The dynamic hip screw (DHS) is widely used for fixing intertrochanteric femur fractures. A porous bionic DHS was developed recently to avoid the stress concentration and risk of post-operative complications associated with titanium alloy DHSs. The purpose of this study was to compare the effects of traditional titanium alloy, bionic titanium alloy, and bionic magnesium alloy DHS fixation for treatment of intertrochanteric fractures using finite element analysis.

METHODS

A three-dimensional model of the proximal femur was established by human computed tomography images. An intertrochanteric fracture was created on the model, which was fixed using traditional and porous bionic DHS, respectively. The von Mises stress, maximum principal stress, and minimum principal stress were calculated to evaluate the effect of bone ingrowth on stress distribution of the proximal femur after fixation.

RESULTS

Stress concentration of the bionic DHS model was lower compared with traditional DHS fixation models. The von Mises stress, maximum principal stress, and minimum principal stress distributions of bionic magnesium alloy DHS models improved, along with simulation of the bone healing process and magnesium alloy degeneration, assumed to biodegrade completely 12 months post-operatively. The distribution of maximum principal stress in the secondary tension zone of the bionic DHS model was close to the intact bone. In the minimum principal stress, the region of minimum stress value less than - 10 MPa was significantly improved compared with traditional DHS models.

CONCLUSION

The bionic magnesium alloy DHS implant can improve the stress distribution of fractured bone close to that of intact bone while reducing the risk of post-operative complications associated with traditional internal fixations.