Buyang Huanwu Decoction Ameliorates Damage of Erectile Tissue and Function Following Bilateral Cavernous Nerve Injury / 中国结合医学杂志

OBJECTIVE@#To verify the effect of Buyang Huanwu Decoction (BHD) in ameliorating erectile dysfunction (ED) after radical prostatectomy (RP).@*METHODS@#The composition of BHD was verified by ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS/MS) analysis. Bilateral cavernous nerve crush injury (BCNI) in rats was used to mimic the neurovascular injury occurring after RP. By the envelope method, forty rats were randomly divided into 4 groups as follows: sham (cavernous nerves exposed only), model (BCNI), low-dosage BHD [LBHD, 12.8 g/(kg·d)], and high-dosage BHD [HBHD, 51.2 g/(kg·d)] groups, 10 rats in each group, feeding for 3 weeks respectively. Erectile function was evaluated by measuring intracavernosal pressure (ICP). Changes in the histopathology of corpus cavernosum (CC) were examined by hematoxylin-eosin staining. Meanwhile, the fibrosis of CC was measured by Masson's trichrome staining and Western blot was used to detect the expressions of collagen I, transforming growth factor beta 1 (TGF- β 1) and α-smooth muscle actin (α-SMA). Apoptosis index was detected by terminal-deoxynucleoitidyl transferase mediated nick end labeling (TUNEL) and Western blot for determining the expressions of B-cell lymphoma 2 (Bcl-2) and Bcl-2-associated X (Bax). The oxidative stress in the CC were assessed by the superoxide dismutase (SOD), malondialdehyde (MDA) and reactive oxygen species (ROS) levels. The proteins expression of c-Jun N-terminal kinase (JNK) and c-Jun were detected by Western blot. In addition, the expression of α-SMA and p-c-Jun in the CC was observed by double immunofluorescence staining.@*RESULTS@#The UPLC-QTOF-MS/MS analysis showed that BHD contained calycosin-7-O- β -D-glucoside, ononin, calycosin and formononetin. Compared with the model group, LBHD and HBHD treatment improved the ICP and the circumference, area, and weight of CC (P<0.05 or P<0.01). Furthermore, LBHD and HBHD treatments increased CC smooth muscle content and decreased apoptosis index (P<0.05 or P<0.01). LBHD and HBHD also elevated SOD and expression level of α -SMA and Bcl-2, and reduced MDA and ROS levels, as well as expression of TGF- β 1, collagen I, Bax, p-c-JNK, p-JNK in the CC compared with the model group (P<0.05 or P<0.01). The double immunofluorescence staining showed that the fluorescence degree of p-c-Jun in both LBHD and HBHD treatment groups was significantly reduced, whereas the α -SMA expression increased (P<0.05 or P<0.01).@*CONCLUSIONS@#BHD can improve ED of rats with BCNI, which is related to inhibiting fibrosis, apoptosis, and oxidative stress of CC. The ROS/JNK/c-Jun signaling pathway may play an important role in the process.

Erectile dysfunction and psychological status in infertile males / 中华男科学杂志

Objective@#To investigate the relationship of erectile dysfunction (ED) with psychological factors in male patients with infertility.@*METHODS@#We conducted a questionnaire investigation among 252 male patients with infertility, which involved the general condition, results of semen routine examination, sexual life, and scores in IIEF-5, self-reported 9-item patient health questionnaire (PHQ-9) and 7-item generalized anxiety disorder scale (GAD-7). We analyzed the prevalence of ED, depression, and anxiety and their correlations among the patients in comparison with 100 fertile male controls.@*RESULTS@#In 245 of the infertility patients, the most common symptoms of depression and anxiety were "feeling tired or no vitality" and "easily getting worried or impatient", 20.4% of them with depression disorder and 42.9% with anxiety disorder. The PHQ-9 and GAD-7 scores were significantly higher in the infertile males than in the normal fertile controls (P <0.05), and so was the incidence of ED (28.6% vs 12.4%, P <0.05), while the IIEF-5 scores were markedly lower in the former than in the latter group (P <0.01), and so were sex frequency and sexual satisfaction (P <0.05). The PHQ-9 and GAD-7 scores were remarkably higher in the infertility patients with ED than in those without (P <0.01). Logistic regression analysis showed that the level of libido and results of semen routine examination were the risk factors for depression disorder, while age, education level, disease course and experience of assisted reproduction were those for anxiety disorder.@*CONCLUSIONS@#Male infertility patients have a poorer mental health and a higher incidence of ED than normal fertile men, and there is some interaction between psychological status and ED prevalence.

Biomechanical properties of trabecular bones in femoral head under loads with different angles / 医用生物力学

Objective To investigate the effects from loads with different angles on morphological and biomechanical properties of trabecular bones in femoral head, so as to provide theoretical basis for studying biomechanical mechanism of necrosis and collapse of femoral head. Methods Ninety-four specimens of 12-month-old ovine trabecular bones in femoral head and forty-three specimens of human cadaver trabecular bones in femoral head were prepared. According to different angles between loading direction and principle compression direction, all the trabecular bones were divided into five groups by 10° interval (i.e. varus 10° and 0°, valgus 10°, 20° and 30°) to simulate the reduction condition under different Garden index after internal fixation of femoral neck fractures. Micro-CT scanning and calculation, compression failure test on ovine trabecular bones in femoral head and cyclic compression test on human cadaver trabecular bones in femoral head were performed to investigate morphological and mechanical indices, including BV/TV (bone volume vs. total volume), BS/BV (bone surface vs. bone volume), Tb.Th (thickness of trabecular bone), Tb.N (number of trabecular bone), Tb.Sp (trabecular separation), elastic modulus, ultimate strength, yield strength, initial secant modulus and number of cycles. Results When the angle between loading direction and principle compression direction of trabecular bones was 0°, BV/TV, Tb.Th, elastic modulus, ultimate strength, yield strength, initial secant modulus and number of cycles for trabecular bones were the maximum while BS/BV and Tb.N were the minimum, and all the formers presented decreasing tendency while BS/BV and Tb.N showed increasing tendency along with the angle increasing. ConclusionsAlong with the angle changes, the tendency of BV/TV and ultimate strength for 12-month-old ovine trabecular bones in femoral head displayed as the same as human trabecular bones in femoral head. Both the morphological and biomechanical properties of trabecular bones in femoral head will decrease when the angle between loading direction and principle compression direction of trabecular bones increases. The more the Garden index deviating from 160°, the more likely trabecular bones in femoral head to be damaged.

Effect of naringin on osteoclast differentiation / 中国中药杂志

<p><b>OBJECTIVE</b>To discuss the effect of Drynariae Rhizoma's naringin on osteoclasts induced by mouse monocyte RAW264.7.</p><p><b>METHOD</b>RAW264.7 cells were induced by 100 μg x L(-1) nuclear factor-κB receptor activator ligand (RANKL) and became mature osteoclasts, which were identified through TRAP specific staining and bone resorption. MTT method was sued to screen and inhibit and the highest concentration of osteoclasts. After being cultured with the screened medium containing naringin for 5 days, positive TRAP cell counting and bone absorption area analysis were adopted to observe the effect of naringin on the formation of osteoclast sells and the bone absorption function. The osteoclast proliferation was measured by flow cytometry. The effects of RANK, TRAP, MMP-9, NFATc1 and C-fos mRNA expressions on nuclear factor-κB were detected by RT-PCR.</p><p><b>RESULT</b>Naringin could inhibit osteoclast differentiation, bone absorption function and proliferation activity of osteoclasts, significantly down-regulate RANK, TRAP, MMP-9 and NFATc1 mRNA expressions in the osteoclast differentiation process, and up-regulate the C-fos mRNA expression.</p><p><b>CONCLUSION</b>Naringin could inhibit osteoclast differentiation, proliferation and bone absorption function. Its mechanism may be achieved by inhibiting the specific gene expression during the osteoclast differentiation process.</p>

Biomechanical comparison of monosegmental and short transpedicular fixation for stabilization of thoracolumbar fractures / 医用生物力学

Objective To establish the monosegmental transpedicular fixation model and short segmental fixation model by three-dimensional finite element technique, and evaluate the biomechanical properties of monosegmental transpedicular fixation for thoracolumbar fractures and verify its feasibility for application. Methods T10-L2 motion segment of a young healthy subject was used to establish the normal finite element model. The superior 1/2 cortical bone of the T12 segment was removed and superior 1/2 cancellous bone of the same vertebrae was assigned material property of the injured bone to simulate the thoracolumbar fracture. Transpedicular screw fixation of the T11 and T12 segment was performed in monosegmental fixation model. T11 and L1 segment were instrumented in the short segmental fixation model. All the four finite element models were applied with loading of axial compression, anteflexion, extension, lateroflexion and axial rotation, respectively. Motion difference of each functional unit and the stress of implants were measured to evaluate biomechanical behaviors of monosegmental fixation. Results The motion difference of all the functional units (T10-11, T11-12, T12-L1) in the fractured model was obviously increased under all loading conditions as compared to the normal model, but the motion difference in the fractured models was decreased after monosegmental fixation and short segmental fixation, and no significant differences were found between monosegmental fixation and short segmental fixation. The stress on screws in monosegmental fixation model was significantly lower than that in short segmental fixation under axial compression and anteflexion, but the stress on screws of two fixation models had no significant difference under extension, lateroflexion and axial rotation. The stress on the rods of monosegmental fixation model was apparently higher than that of short segmental fixation under extension and lateroflexion, and lower under axial rotation, but no significant difference was found for two fixation models under axial compression and anteflexion. Conclusions Monosegmental transpedicular screw fixation would give the similar stabilization as short segmental fixtion and could be an effective alternative to treat incomplete fractures in thoracolumbar spine.

Preparation and biomechanical properties of acellularized nerve scaffold using the technique of hypotonic buffer combined with freeze-drying / 医用生物力学

Objective To study the morphology and biomechanical properties of the improved acellularized nerve scaffold using the technique of hypotonic buffer combined with freeze-drying. Methods The traditional acellularized nerve scaffold (traditional group) was made to be improved with the technique of hypotonic buffer combined with freeze-drying (improved group). After the acellularization process was completed, the histological structure of nerves in each group was observed by HE staining and scanning electron microscope. The interval porosity and void diameter in each group were measured by Mimics software. The biomechanical properties of nerves in each group were tested by mechanical apparatus (Endura TEC ELF3200). Results The acellularization effect of the improved chemical method with the technique of hypotonic buffer combined with freeze-drying was similar to that of the traditional Hudson method, but the histological structure was more porous in improved group than that in traditional group. The interval porosity of traditional group and improved group were 34.5% and 49.3%, respectively; the void diameter of traditional group and improved group were 11.96 and 17.61 μm, respectively. Biomechanical testing results showed that there was no statistical difference in ultimate load, ultimate stress, ultimate strain and mechanical work to fracture in each group (P>0.05). Conclusions The acellularized nerve prepared by hypotonic buffer combined with freeze-drying can be used as a new kind of nerve scaffold material to make better contribution to cell combination.

Biomechanical differences of embalmed and PMMA femurs / 医用生物力学

Objective To compare the differences in biomechanical properties of embalmed and PMMA femurs under axial loads, so as to provide a more reliable and unified femoral model for replacement. Methods Ten embalmed femurs and ten PMMA femurs were selected, and each femur was instrumented with 49 strain gauges totally on the medial and lateral side. The axial load was applied dynamically up to a maximum of 1.2 kN, and the strain of each strain gauge and load displacement curve were recorded. Results The strain distributions on two types of femur were similar, and the load displacement presented a linear relationship, but the vertical displacements under different loads were significantly different (P<0.05). The axial stiffness value of PMMA femur and embalmed femur were (259.84±24.63) and (600.40±78.56) N/mm, respectively, showing significant difference (P<0.01). The strain concentration parts at the proximal part of two femurs were the same, but the average strain value of the PMMA femur was significantly different from that of the embalmed femur (strain gauge No. 1~5: PMMA femur (-3 420.63±373.31) με, embalmed femur (-1 289.42±417.89) με; strain gauge No. 26~27: PMMA femur (1 748.67±193.98) με, embalmed femur (673.42±104.49) με; strain gauge No. 7~10: PMMA femur (-4 028.25±267.27) με, embalmed femurs (-1 139.01±288.83) με; strain gauge No. 30~36: PMMA femur (1 599.02±194.68) με, embalmed femurs (590.52±153.18) με, P<0.01). The strain concentration parts at the distal part of the two femurs were different. The medial and lateral parts of strain transformation between positive and negative of PMMA femurs were similar to embalmed femurs. The strain-load curves of strain gauge No. 2, 26, 6, 29, 8 and 33 indicated a linear relationship, but the strain value of the two femurs had significant differences (P<0.05). Conclusions The PMMA femur can replace the embalmed femur to a certain degree in biomechanical experiments on the upper part of femur. Due to the difficulty of obtaining fresh femurs, the PMMA femurs provide a more reliable and unified femoral model for replacement.

Biomechanical study on open fracture model with plate fixation compared with closed fracture model with intramedullary nail fixation in rats / 中国骨伤

<p><b>OBJECTIVE</b>To compare biomechanical effect of the closed fracture model with intramedullary nail fixation and the open fracture model with plate fixation in rats.</p><p><b>METHODS</b>Forty 8-week-old Spragu-Dawley male rats were divided into two groups randomly. Left femoral shaft closed fractures model was created in 20 rats, and treated with intramedullary nail. Other 20 rats received open osteotomy on the left femoral shaft, and were fixed by plate. Rats were sacrificed and draw the materials at 4, 6, 8 and 12 weeks in batch. Across section area and volume of callus were measured, peak load, restoration rate of peak load were tested. The biomechanical efficency of two methods of femoral shaft fracture fixation were compared.</p><p><b>RESULTS</b>The difference of surgical duration was statistically significant between two groups (P < 0.001). At 4, 6, 8 and 12 weeks, the difference of peak load, restoration rate of peak load, volume and area of callus was also statistically significant between two groups (P < 0.05).</p><p><b>CONCLUSION</b>Open fracture model with plate fixation led to delayed healing compared with closed fracture model with intramedullary nail. However, open fracture model with plate fixation model could be a valuable research tool to study the healing consequences of cortical bone, which may provide insight into the pathogenesis and ideal treatment of fractures or nonunions.</p>

Influence of anteversion angles on stress distributions of the proximal femur after femoral neck fracture fixation: A finite element analysis / 医用生物力学

Objective To investigate the effects of different anteversion angles on stress distributions of the proximal femur after femoral neck fracture fixation by cannulated screw, and to provide biomechanical evidences for the importance of anatomical reduction in internal fixation in clinic. Methods Femoral neck fracture with Pauwells angle 70°was treated with cannulated screw internal fixation, and its three-dimensional finite element models with five different anteversion angles set at 0°，5°，10°，15°and 20°, respectively, were constructed based on normal human anatomical data from multi slice spiral CT as well as reverse engineering and CAD software. Loads were applied on each model to simulate normal walking status. Changes in stress distributions of the proximal femur in each model were observed. Results When the anteversion angle was 10°, the stress, displacement and equivalent strain of the femur was were the minimum, as the maximum stress of the proximal femur was 1.7 MPa, and the displacement was 1.1 mm. With the anteversion angle increasing or decreasing, the effective stress and displacement of the proximal femur was gradually increasing. When the anteversion angle was 20°, the stress of on the proximal femur and on the cannulated screw was became the maximum. When the anteversion angle was 0°, the displacement and equivalent strain of the femur also became the maximum. The stress concentration site of the femoral neck was gradually transferred from the inside rear to the outer top of the head and neck junction. The three cannulated screws there stood the higher stress than the surrounding bone tissues, and with the bottom screw stood the higher stress than the other top two screws. Conclusions Anatomic reduction is essential for femoral neck fracture fixation treated by cannulated screw. Changes in biomechanical factors after femoral neck fracture may play an important role in postoperative femoral head necrosis.

Unilateral versus bilateral pedicle screw fixation in lumbar spinal fusion: a meta-analysis of available evidence / 中华外科杂志

<p><b>OBJECTIVE</b>To evaluate the effectiveness of unilateral versus bilateral pedicle screw fixation in lumbar spinal fusion.</p><p><b>METHODS</b>Studies on comparison between unilateral and bilateral pedicle screw fixation in lumbar spinal fusion were identified from Medline, EMBASE, Cochrane CENTRAL (Third Quarter 2011), ScienceDirect, OVID, SpringerLink and The China Biological Medicine Database, and searched several related journals by hand. The included trials were screened out according to the criterion of inclusion and exclusion. The quality of included trials was evaluated. Data were extracted by two reviewers independently. RevMan 5.1.1 was used for data analysis.</p><p><b>RESULTS</b>Seven studies involving 480 patients were included, 246 in unilateral group, and 234 in bilateral group. The results of meta-analysis indicated that statistically significant difference were observed between the two fixation procedures in mean operation time (MD = -24.39, 95%CI: -33.16 to 15.61, P < 0.01), the amount of bleeding (MD = -118.73, 95%CI: -143.43 to -94.03, P < 0.01). There were no difference in inpatient stay, fusion rate, complication rate and excellent and good rate.</p><p><b>CONCLUSIONS</b>Both unilateral and bilateral pedicle screw fixation are effective in lumbar spinal fusion. To compare with bilateral fixation, unilateral fixation can shorten operation time, reduce amount of bleeding and medical expenses. And there is a similar effect of inpatient stay, fusion rate, complication rate and excellent and good rate.</p>

Three-dimensional reconstruction study of the displacement of undisplaced femoral neck fractures / 中华外科杂志

<p><b>OBJECTIVE</b>To measure the displacement parameters of femoral head in space through three-dimensional reconstruction so as to reunderstand undisplaced femoral neck fractures.</p><p><b>METHODS</b>The clinical data of 80 undisplaced femoral neck fractures from January 2010 to June 2011 were selected, included Garden I 40 cases (group Garden I) and Garden II 40 cases (group Garden II), bilateral proximal femurs of everyone were scanned by CT and reconstructed by professional software. Registered the normal femur and fracture with mirror model, marked key points in the model and measured the displacement parameters of femoral head. The measurement accuracy of distance and angle were 0.01 mm and 0.01°, respectively. The parameters of femoral head displacement between group Garden I and Garden II were analyzed by independent-sample t-test.</p><p><b>RESULTS</b>Eighty cases on X-ray films were not found rotated displacement. But 24 cases of them (30.0%) showed rotated displacement and rotation direction of the femoral head through three-dimensional reconstruction. Ten cases showed incomplete fractures on X-ray films, but only 3 cases were incomplete fractures with three-dimensional reconstruction. In group Garden I, the femoral head displacement angle was 18° ± 11°, the average displacement distance of femoral head center and deepest point of fovea capitis were (6 ± 3) mm and (10 ± 6) mm respectively. In group Garden II, the femoral head displacement angle was 17° ± 10°, the average displacement distance of femoral head center and deepest point of fovea capitis were (7 ± 5) mm and (13 ± 8) mm respectively. There were not statistical significance of the parameters of femoral head displacement between group Garden I and Garden II (P > 0.05).</p><p><b>CONCLUSIONS</b>Three-dimensional reconstruction and digital measurement is a precise, efficient method for the measurement of femoral head displacement parameters in femoral neck fractures, has important clinical significance in the diagnosis and treatment of the femoral neck fractures. There are certain defects and limitations of the classical Garden classification for undisplaced femoral neck fractures.</p>

Clinical efficiency of computer-assisted pedicle screw placement versus conventional method: a meta-analysis / 中国骨伤

<p><b>OBJECTIVE</b>To compare the clinical efficacy of computer-assisted pedicle screw placement and conventional placement in the treatment of spinal disease.</p><p><b>METHODS</b>A systematic search of studies published between Jan. 1990 and Feb. 2012 was conducted using Medline, Embase, OVID, ScienceDirect and Cochrane Review databases. Randomized controlled trials (RCTs) and prospective controlled trials of comparing computer-assisted pedicle screw placement to conventional method performed at one center or multi-centers providing data on accuracy of placement and clinical effects were identified. Two study authors independently reviewed the 93 articles originally identified and selected 10 for analysis. Study title,demographic characteristics,number of pedicle screw,anatomical area and outcomes were extracted manually from all selected studies. RevMan 5.1 software was used for meta-analysis.</p><p><b>RESULTS</b>Ten studies encompassing 2813 pedicle screws met the inclusion criteria. Overall,the result of meta-analysis indicated that there were significant differences between two groups in accuracy in placement of pedicle screw [OR = 2.58, 95% CI (1.18, 5.63)], insertion time [WMD = -2.15, 95% CI (-2.36, -1.94)]. However, there was only one study reported preparation time of pedicle screw of navigation group was longer than conventional group. No neurological complication in navigation group was reported.</p><p><b>CONCLUSION</b>As a safety supplementary measure, computer navigation provide better accuracy in placement of pedicle screw and insertion time. The preparation time of pedicle screw may prolong due to the complexity of navigation system. Further reseach should include randomized controlled trials with well-planned methodology to limit bias.</p>

Test on compressive properties of trabecular bone in proximal femur using digital image correlation technique / 医用生物力学

Objective To improve the method used for traditional compression test to reflect the compressive elastic modulus of trabecular bone in proximal femur more accurately and investigate its biomechanical properties to provide experimental evidences for clinical treatment. Methods The properties of trabecular bone from normal cadaveric proximal femur(45~60 years old) were measured by the micro material mechanics testing system. Results The elastic modulus in the direction of principle compression and principle tension on trabecular bone were (335.26±183.85) MPa and (59.27±23.88) MPa, respectively. The biomechanical properties of trabecular bone in the direction of principle compression were significantly higher than those in its vertical direction.The displacement and strain distribution profiles under the loading were recorded, which showed to be asymmetric. Conclusions It is feasible to test the biomechanical properties of trabecular bone more accurately by the micro material mechanics testing system. The compressive properties of trabecular bone in proximal femur are obviously anisotropic and heterogeneous.

Biomechanical properties of peripheral nerve after acellular treatment / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Peripheral nerve injury causes a high rate of disability and a huge economic burden, and is currently one of the serious health problems in the world. The use of nerve grafts plays a vital role in repairing nerve defects. Acellular nerve grafts have been widely used in many experimental models as a peripheral nerve substitute. The purpose of this study was to test the biomechanical properties of acellular nerve grafts.</p><p><b>METHODS</b>Thirty-four fresh sciatic nerves were obtained from 17 adult male Wistar rats (age of 3 months) and randomly assigned to 3 groups: normal control group, nerve segments underwent no treatment and were put in phosphate buffered saline (pH 7.4) and stored at 4°C until further use; physical method group, nerve segments were frozen at -196°C and then thawed at 37°C; and chemical method group, nerve segments were chemically extracted with the detergents Triton X-200, sulfobetaine-10 (SB-10) and sulfobetaine-16 (SB-16). After the acellularization process was completed, the structural changes of in the sciatic nerves in each group were observed by hematoxylin-eosin staining and field emission scanning electron microscopy, then biomechanical properties were tested using a mechanical apparatus (Endura TEC ELF 3200, Bose, Boston, USA).</p><p><b>RESULTS</b>Hematoxylin-eosin staining and field emission scanning electron microscopy demonstrated that the effects of acellularization, demyelination, and integrity of nerve fiber tube of the chemical method were better than that of the physical method. Biomechanical testing showed that peripheral nerve grafts treated with the chemical method resulted in some decreased biomechanical properties (ultimate load, ultimate stress, ultimate strain, and mechanical work to fracture) compared with normal control nerves, but the differences were not statistically significant (P > 0.05).</p><p><b>CONCLUSION</b>Nerve treated with the chemical method may be more appropriate for use in implantation than nerve treated with the physical method.</p>

Finite element study on spatial distribution and mechanical properties of cancellous bone from femoral head / 医用生物力学

Objective To study the effect of different loading intensity and off axis angle on changes in spatial distribution and mechanical properties of cancellous bone from femoral head by using three dimensional(3D) finite element method. Method The same size cancellous bone specimens were selected in accordance with the main pressure trabecular direction at 0°, 15°and 45° off axis angle from 3D model of proximal femoral bone structure based on primary study. The 3D structure parameters of the specimen were calculated, then the finite element analysis was used to simulate the uniaxial compression test, and the stress and strain distribution in different model was observed. The influences of different loading intensity and off-axis angle on biomechanical properties of proximal femoral cancellous bone were investigated. Results Based on the established finite element model of cancellous bone of human femoral head, the uniaxial compression test was simulated. It was found that there were significant differences in the proportion of cancellous bone with ≥5 000μ strain in different mechanical strength or off axis angle on cancellous bone specimens（P<0.05）. Conclusions Distribution of femoral head cancellous bone is closely related with the mechanical adaptability. The incompatibility between structure and function decreased the biomechanical properties of femoral head cancellous bone and the subsequent bone remodeling caused by repeated negative stimulus may play an important role in femoral head necrosis.