The force at the implant cannot be assessed by the mallet force-Unless supported by a model.

The implantation of uncemented prostheses requires the application of sufficient forces to achieve a press-fit of the implant in the bone. Excessive forces have to be omitted to limit bone damage. Force measurements along the force transmission path between mallet and implant are frequently used to investigate this trade-off. Placing a load cell at a position of interest (PoI), which might be the implant bone interface or the head taper junction, is technically challenging or even impossible so that nearby positions are chosen. Thus, a certain inertia and stiffness remain between the PoI and the sensor, and consequently the measured dynamic forces differ from those at the PoI. This experimental and numerical study aimed to investigate the amount of force reduction along the transmission path while joining femoral heads to stem tapers. Forces were measured in vitro at the tip of the mallet, directly above the polymer tip of the impactor and below the stem taper. Springs and masses were used to represent the responding tissue of a patient. A semi-empirical numerical model of the force transmission path was developed and validated in order to simulate a larger range of responding tissue properties than experimentally possible and to investigate the influence of different surgical instruments. A distinct attenuation was observed since the peak forces at the impactor reached 35% of the applied peak forces and 21% at the stem taper, respectively. The force curves were replicated with a median root mean square error of 3.8% of the corresponding mallet blow for the impactor and 3.6% for the stem. The force measurement position and the used surgical instruments have a strong influence on the measured forces. Consequently, the exact measurement conditions with regard to sensor positioning and used surgical instruments have to be specified and hence only studies with similar setups should be compared to avoid misestimation of the forces at the PoI. The proposed dynamic numerical model is a useful tool to calculate the impact of the chosen or changed mechanical parameters prior to executing experiments and also to extrapolate the effect of changing the applied forces to the resulting forces at the PoI.

Human umbilical cord mesenchymal stem cells promote steroid-induced osteonecrosis of the femoral head repair by improving microvascular endothelial cell function.

Recently, there has been growing interest in using cell therapy through core decompression (CD) to treat osteonecrosis of the femoral head (ONFH). Our study aimed to investigate the effectiveness and mechanism of human umbilical cord mesenchymal stem cells (hUCMSCs) in treating steroid-induced ONFH. We constructed a steroid-induced ONFH rabbit model as well as dexamethasone (Dex)-treated bone microvascular endothelial cells (BMECs) model of human femoral head. We injected hUCMSCs into the rabbit femoral head via CD. The effects of hUCMSCs on steroid-induced ONFH rabbit model and Dex-treated BMECs were evaluated via micro-CT, microangiography, histology, immunohistochemistry, wound healing, tube formation, and western blotting assay. Furthermore, we conducted single-cell RNA sequencing (scRNA-seq) to examine the characteristics of endothelial cells, the activation of signaling pathways, and inter-cellular communication in ONFH. Our data reveal that hUCMSCs improved the femoral head microstructure and bone repair and promoted angiogenesis in the steroid-induced ONFH rabbit model. Importantly, hUCMSCs improved the migration ability and angioplasty of Dex-treated BMECs by secreting COL6A2 to activate FAK/PI3K/AKT signaling pathway via integrin α1ß1.

[α2-macroglobulin alleviates glucocorticoid-induced avascular necrosis of the femoral head in mice by promoting proliferation, migration and angiogenesis of vascular endothelial cells].

OBJECTIVE: To explore the mechanism underlying the protective effect of α2-macroglobulin (A2M) against glucocorticoid-induced femoral head necrosis. METHODS: In a human umbilical vein endothelial cell (HUVEC) model with injuries induced by gradient concentrations of dexamethasone (DEX; 10-8-10-5 mol/L), the protective effects of A2M at 0.05 and 0.1 mg/mL were assessed by examining the changes in cell viability, migration, and capacity of angiogenesis using CCK-8 assay, Transwell and scratch healing assays and angiogenesis assay. The expressions of CD31 and VEGF-A proteins in the treated cells were detected using Western blotting. In BALB/c mouse models of avascular necrosis of the femoral head induced by intramuscular injections of methylprednisolone, the effects of intervention with A2M on femoral trabecular structure, histopathological characteristics, and CD31 expression were examined with Micro-CT, HE staining and immunohistochemical staining. RESULTS: In cultured HUVECs, DEX treatment significantly reduced cell viability, migration and angiogenic ability in a concentration- and time-dependent manner (P<0.05), and these changes were obviously reversed by treatment with A2M in positive correlation with A2M concentration (P<0.05). DEX significantly reduced the expression of CD31 and VEGF-A proteins in HUVECs, while treatment with A2M restored CD31 and VEGF-A expressions in the cells (P<0.05). The mouse models of femoral head necrosis showed obvious trabecular damages in the femoral head, where a large number of empty lacunae and hypertrophic fat cells could be seen and CD31 expression was significantly decreased (P<0.05). A2M treatment of the mouse models significantly improved trabecular damages, maintained normal bone tissue structures, and increased CD31 expression in the femoral head (P<0.05). CONCLUSION: A2M promotes proliferation, migration, and angiogenesis of DEX-treated HUVECs and alleviates methylprednisolone-induced femoral head necrosis by improving microcirculation damages and maintaining microcirculation stability in the femoral head.

Finite element study on the micromechanics of cement-augmented proximal femoral nail anti-rotation (PFNA) for intertrochanteric fracture treatment.

Blade cut-out is a common complication when using proximal femoral nail anti-rotation (PFNA) for the treatment of intertrochanteric fractures. Although cement augmentation has been introduced to overcome the cut-out effect, the micromechanics of this approach remain to be clarified. While previous studies have developed finite element (FE) models based on lab-prepared or cadaveric samples to study the cement-trabeculae interface, their demanding nature and inherent disadvantages limit their application. The aim of this study was to develop a novel 'one-step forming' method for creating a cement-trabeculae interface FE model to investigate its micromechanics in relation to PFNA with cement augmentation. A human femoral head was scanned using micro-computed tomography, and four volume of interest (VOI) trabeculae were segmented. The VOI trabeculae were enclosed within a box to represent the encapsulated region of bone cement using ANSYS software. Tetrahedral meshing was performed with Hypermesh software based on Boolean operation. Finally, four cement-trabeculae interface FE models comprising four interdigitated depths and five FE models comprising different volume fraction were established after element removal. The effects of friction contact, frictionless contact, and bond contact properties between the bone and cement were identified. The maximum micromotion and stress in the interdigitated and loading bones were quantified and compared between the pre- and post-augmentation situations. The differences in micromotion and stress with the three contact methods were minimal. Micromotion and stress decreased as the interdigitation depth increased. Stress in the proximal interdigitated bone showed a correlation with the bone volume fraction (R2 = 0.70); both micromotion (R2 = 0.61) and stress (R2 = 0.93) at the most proximal loading region exhibited a similar correlation tendency. When comparing the post- and pre-augmentation situations, micromotion reduction in the interdigitated bone was more effective than stress reduction, particularly near the cement border. The cementation resulted in a significant reduction in micromotion within the loading bone, while the decrease in stress was minimal. Noticeable gradients of displacement and stress reduction can be observed in models with lower bone volume fraction (BV/TV). In summary, cement augmentation is more effective at reducing micromotion rather than stress. Furthermore, the reinforcing impact of bone cement is particularly prominent in cases with a low BV/TV. The utilization of bone cement may contribute to the stabilization of trabecular bone and PFNA primarily by constraining micromotion and partially shielding stress.

Autologous concentrated bone marrow injection for precollapse osteonecrosis of the femoral head concurrent with contralateral total hip arthroplasty: protocol for a clinical trial.

INTRODUCTION: The femoral head contralateral to the collapsed femoral head requiring total hip arthroplasty (THA) often manifests in the precollapse stage of osteonecrosis of the femoral head (ONFH). It is not yet demonstrated how autologous concentrated bone marrow injection may prevent collapse of the femoral head concurrent with contralateral THA. The primary objective is to evaluate the efficacy of autologous concentrated bone marrow injection for the contralateral, non-collapsed, femoral head in patients with bilateral ONFH, with the ipsilateral collapsed femoral head undergoing THA. METHODS AND ANALYSIS: This is a multicentre, prospective, non-randomised, historical-data controlled study. We will recruit patients with ONFH who are scheduled for THA and possess a non-collapsed contralateral femoral head. Autologous bone marrow will be collected using a point-of-care device. After concentration, the bone marrow will be injected into the non-collapsed femoral head following the completion of THA in the contralateral hip. The primary outcome is the percentage of femoral head collapse evaluated by an independent data monitoring committee using plain X-rays in two directions 2 years after autologous concentrated bone marrow injection. Postinjection safety, adverse events, pain and hip function will also be assessed. The patients will be evaluated preoperatively, and at 6 months, 1 year and 2 years postoperatively. ETHICS AND DISSEMINATION: This protocol has been approved by the Certified Committee for Regenerative Medicine of Tokyo Medical and Dental University and Japan's Ministry of Healthy, Labour and Welfare and will be performed as a class III regenerative medicine protocol, in accordance with Japan's Act on the Safety of Regenerative Medicine. The results of this study will be submitted to a peer-review journal for publication. The results of this study are expected to provide evidence to support the inclusion of autologous concentrated bone marrow injections in the non-collapsed femoral head in Japan's national insurance coverage. TRIAL REGISTRATION NUMBER: jRCTc032200229.

[Clinical study on the incidence of femoral head posterior tilt angle in non-displaced femoral neck fractures].

OBJECTIVE: To investigate the occurrence of posterior femoral head tilt after clinical non-displaced femoral neck fracture, and to provide a reference basis for clinical surgery and improvement of disease prognosis. METHODS: Total of 165 patients with non-displaced femoral neck fractures of Garden typeⅠandⅡfrom January 2018 to June 2022 were selected as study subjects including 48 males and 117 females, with an average age of (71.5±8.5) years old ranging from 53 to 89, involving 97 cases of typeⅠand 68 of typeⅡ. On the patient's preoperative sagittal or axial CT film of the hip, the angle formed by the radius line of the femoral head and the midline of the femoral neck was used as the posterior tilt angle of the femoral head (α), and the posterior tilt femoral head angle was measured using the method proposed by Palm. The measured data were divided into 6 groups:α<0°, 0°<α< 5°, 5°≤α<10°, 10°≤α<15°, 15°≤α<20°, α≥20°, and the incidence of different ranges of posterior tilt angle was compared. The sex composition ratio of 165 patients were analyzed and compared, and the age of 65 was used as the cut-off point to compare the incidence of fractures between genders. Patients were divided into the posterior tilt <20° group for 135 cases and the posterior tilt ≥20°group for 30 cases according to the preoperative posterior tilt angle, the differences between two groups in terms of gender and age were analyzed. RESULTS: Among 165 patients with non-displaced femoral neck fractures, 143 cases with poaterior tilt of the femoral head occurred with an incidence of 86.7%. Posterior tilt 0°<α<5° accounted for 36 cases with an incidence of 21.8%;5°≤α<10° accounted for 40 cases with an incidence of 24.2%;10°≤α<15° accounted for 27 cases with an incidence of 16.4%;15°≤α<20° accounted for 10 cases with an incidence of 6.1%;posterior tilt angle α≥20° accounted for 30 cases, the incidence was 18.2%, of which the maximum posterior tilt angle was 42.7°. Statistical analysis showed that the percentage of fractures in the 165 patients selected for this study was significantly higher in female than in male, and that the female group was more likely to have fractures before the age of 65 years compared to the male group. However, gender, age and fracture subtypes (GardenⅠ, Ⅱ) were not influential factors for femoral neck fractures with a preoperative posterior femoral head tilt angle >20°(P>0.05). CONCLUSION: The incidence of femoral head posterior tile in non-displaced femoral neck fractures is relatively high, in which severe posterior tile occurs, and the femoral head posterior tile angle≥20° can reach 18.2%. In patients with closed reduction internal fixation, the fracture end needs to be repositioned as much as possible to reduce the risk of postoperative avascular necrosis of the femoral head. In order to prevent femoral neck fractures, special attention should be paid to anti-osteoporosis treatment for female. Preoperative assessment of posterior tilt is critical for patients of different ages, genders and fracture subtypes (GardenⅠ, Ⅱ).

Extending the intermedullary nail will not reduce the potential risk of femoral head varus in PFNA patients biomechanically: a clinical review and corresponding numerical simulation.

Femoral head varus is an important complication in intertrochanteric fracture patients treated with proximal femoral nail anti-rotation (PFNA) fixation. Theoretically, extending the length of the intramedullary nail could optimize fixation stability by lengthening the force arm. However, whether extending the nail length can optimize patient prognosis is unclear. In this study, a review of imaging data from intertrochanteric fracture patients with PFNA fixation was performed, and the length of the intramedullary nail in the femoral trunk and the distance between the lesser trochanter and the distal locking screw were measured. The femoral neck varus status was judged at the 6-month follow-up. The correlation coefficients between nail length and femoral neck varus angle were computed, and linear regression analysis was used to determine whether a change in nail length was an independent risk factor for femoral neck varus. Moreover, the biomechanical effects of different nail lengths on PFNA fixation stability and local stress distribution have also been verified by numerical mechanical simulations. Clinical review revealed that changes in nail length were not significantly correlated with femoral head varus and were also not an independent risk factor for this complication. In addition, only slight biomechanical changes can be observed in the numerical simulation results. Therefore, commonly used intramedullary nails should be able to meet the needs of PFNA-fixed patients, and additional procedures for longer nail insertion may be unnecessary.

The small screw-apex distance is potentially associated with femoral head osteonecrosis in adults with femoral neck fractures treated by closed reduction and percutaneous 3 parallel cannulated screws.

OBJECTIVE: Femoral neck fractures (FNFs) are among the most common fractures in elderly individuals. Surgery is the main treatment for FNFs, and osteonecrosis of the femoral head (ONFH) is one of the unacceptable complications. This study aimed to assess both the clinical and radiological outcomes in patients with FNFs treated with three parallel cannulated screws and to identify relationship between screws position and ONFH. PATIENTS AND METHODS: A total of 100 patients who were treated with closed reduction and fixed with 3 parallel cannulated screws met the inclusion criteria between January 2014 and December 2020 at authors' institution. The follow-up duration, age, sex, affected side, and injury-to-surgery interval were collected; the neck-shaft angle of both hips, screw-apex distance (SAD) and the tip-apex distance (TAD)were measured; and the Garden classification, quality of reduction and presence of ONFH were evaluated. RESULTS: The sample consisted of 37 males and 63 females, with 60 left and 40 right hips affected. The mean age of patients was 54.93 ± 12.24 years, and the mean follow-up was 56.3 ± 13.38 months. The overall incidence of ONFH was 13%. No significant difference was observed in the incidence of ONFH by affected side, age, fracture displacement, injury-to-surgery interval, neck-shaft angle deviation, or reduction quality. The SAD was significantly shorter in ONFH patients than in normal patients for all three screws (p = 0.02, 0.02, and 0.01, respectively). CONCLUSIONS: The short SAD of all screws is associated with femoral head necrosis of FNFs treated with 3 cannulated screws. The short SAD indicated that screws malpositioning in the weight-bearing area of the femoral head, potentially harming the blood supply and compromising the anchorage of the primary compressive trabeculae in this region.

Application direct anterior approach in pediatric femoral head and neck lesions.

BACKGROUND: Femoral neck is one of the high-risk areas for benign tumors and tumor-like lesions. Small range of lesions may also lead to pathological fracture, femoral head necrosis and other serious problems. PURPOSE: To investigate a new minimally invasive surgical approach to resect femoral head and neck lesions in children. PATIENTS AND METHODS: Retrospective study of 20 patients with femoral neck and femoral head lesions from February 2019 to March 2023 in our hospital. Among them, 14 were boys and 6 were girls, 17 were femoral neck lesions and 3 were femoral head lesions. The age of the patients ranged from 3.2 to 12.6 years, with a mean of 7.1 years. The patients were divided into group A and group B according to different surgical approaches; group A used the Smith-Peterson approach, Watson-Jones approach or surgical dislocation approach and group B used the DAA. Intra-operatively, incision length, operative time and blood loss were recorded in both groups. Group A consisted of 1 femoral head lesion and 8 femoral neck lesions, including 5 cases of bone cyst and 4 cases of eosinophilic granuloma. Group B consisted of 2 femoral head lesion and 9 femoral neck lesions. A total of 11 patients with different types of disease were included in group B, including bone cysts (3 cases), aneurysmal bone cysts (1 case), eosinophilic granulomas (6 cases), Kaposi's sarcoma (1 case). RESULTS: The two groups of patients differed in terms of incision length (P < 0.05), operative blood loss (P < 0.05) and operative time (P < 0.05). At 6-48 months post-operatively, there were no significant differences in function and all patients had good hip function. CONCLUSION: The direct anterior approach is effective for resection of paediatric femoral head and neck lesions. It provides clear exposure of the surgical site, minimal trauma and does not compromise the integrity of the anterior musculature. LEVEL OF EVIDENCE: III.

Lower Risk of Revision With 32- and 36-Millimeter Femoral Heads Compared With 28-mm Heads in Primary Total Hip Arthroplasty: A Comparative Single-Center Study (10,104 Hips).

BACKGROUND: We aimed to compare the clinical outcomes of different head sizes (28-, 32-, and 36- millimeter) in primary total hip arthroplasty (THA) at mean 6 years follow-up (range, 1 to 17.5 years). METHODS: This was a retrospective consecutive study of primary THA at our institution (2003 to 2019). Demographic and surgical data were collected. The primary outcome measures were all-cause revision, revision for dislocation, and all-cause revision excluding dislocation. Continuous descriptive statistics used means, median values, ranges, and 95% confidence intervals, where appropriate. Kaplan-Meier survival curves were used to estimate time to revision. Cox proportional hazard regression analyses were used to compare revision rates between the femoral head size groups. Adjustments were made for age at surgery, sex, primary diagnosis, American Society of Anesthesiologists score, articulation type, and fixation methods. There were 10,104 primary THAs included; median age was 69 years (range, 13 to 101) with 61.5% women. A posterior approach was performed in 71.6%. There were 3,295 hips with 28-mm heads (32.6%), 4,858 (48.1%) with 32-mm heads, and 1,951 (19.3%) with 36-mm heads. RESULTS: Overall rate of revision was 1.7% with the lowest rate recorded for the 36-mm group (2.7 versus 1.3 versus 1.1%). Cox regression analyses showed a decreased risk of all-cause revision for 32 and 36-mm head sizes as compared to 28-mm; this was statistically significant for the 32-mm group (P = .01). Risk of revision for dislocation was significantly reduced in both 32-mm (P = .03) and 36-mm (P = .03) head sizes. Analysis of all cause revision excluding dislocation showed no significant differences between head sizes. CONCLUSIONS: We found a significantly reduced risk of revision for all causes, but particularly revision for dislocation with larger head sizes. Concerns regarding increased risk of early revision for aseptic loosening, polyethylene wear, or taper corrosion with larger heads appear to be unfounded in this cohort of 10,104 patients with up to 17 years follow-up.

[Transcriptome data mining combined with clinical and animal experiments for identification of syndrome element marker genes during entire course of steroid-induced osteonecrosis of femoral head].

A research strategy combining transcriptome data mining and experimental verification was adopted to identify the marker genes characterizing the syndrome elements of phlegm, stasis, and deficiency in steroid-induced osteonecrosis of the femoral head(SONFH). Firstly, the common differentially expressed gene sets of SONFH with the syndromes of phlegm-stasis obstructing collaterals, vessel obstruction, and liver-kidney deficiency were obtained from the clinical transcriptomic analysis of a previous study. The differential expression trend analysis and functional gene mining were then employed to predict the candidate marker gene sets representing phlegm, stasis, and deficiency. The whole blood samples from SONFH patients, whole blood samples from SONFH rats, and affected femoral head tissue samples were collected for qPCR, which aimed to determine the expression levels of the candidate marker genes mentioned above. Furthermore, the receiver operating characteristic curve(ROC) was established to objectively evaluate the syndrome differentiation effectiveness of the candidate marker genes mentioned above. The transcriptome data analysis results showed that the candidate marker genes for phlegm was ELOVL fatty acid elongase 6(ELOVL6), and those for stasis were ankyrin 1(ANK1), glycophorin A/B(GYPA/B), and Rh-associated glycoprotein(RHAG). The candidate marker genes for deficiency were solute carrier family 2 member 1(SLC2A1) and stomatin(STOM). The qPCR results showed that compared with that in the non-SONFH group, ELOVL6 had the lowest expression level in the peripheral blood of the SONFH patients with the syndrome of phlegm-stasis obstructing collaterals(P<0.05). Compared with that in the normal control group, ELOVL6 had the lowest expression level in the peripheral blood and affected femoral head tissue of SONFH rats modeled for 4 weeks(P<0.01), and it showed better syndrome differentiation effectiveness of rats modeled for 4 weeks(AUC=0.850, P=0.006) than at other modeling time points(8, 12, 16, and 21 weeks, AUC of 0.689, 0.766, 0.588, and 0.662, respectively). Compared with that in the non-SONFH group, the expression levels of ANK1, GYPA, and RHAG were the lowest in the peripheral blood of SONFH patients with the vessel obstruction syndrome(P<0.05). The expression levels of the three genes were the lowest in the peripheral blood and affected femoral head tissue of SONFH rats modeled for 12 weeks(P<0.05, P<0.01), and their syndrome differentiation effectiveness in the rats modeled for 12 weeks(GYPA: AUC=0.861, P=0.012; ANK1: AUC=0.855, P=0.006; RHAG: AUC=0.854, P=0.009) was superior to that for 4, 8, 16, and 21 weeks(GYPA: AUC=0.646, 0.573, 0.691, and 0.617, respectively; ANK: AUC1=0.630, 0.658, 0.657, and 0.585, respectively; RHAG: AUC=0.592, 0.511, 0.515, and 0.536, respectively). Compared with the non-SONFH group, both SLC2A1 and STOM had the lowest expression levels in the peripheral blood of patients with the syndrome of liver and kidney deficiency(P<0.05). Compared with the normal control group, their expression levels were the lowest in the peripheral blood and affected femoral head tissue of SONFH rats modeled for 21 weeks(P<0.05, except STOM in the peripheral blood of rats). Moreover, the syndrome differentiation effectiveness of SLC2A1 in the rats modeled for 21 weeks(AUC=0.806, P=0.009) was superior to that for 4, 8, 12, and 16 weeks(AUC=0.520, 0.580, 0.741, 0.774, respectively), and STOM was meaningless in syndrome differentiation. In summary, the candidate marker gene for phlegm in SONFH is ELOVL6; the candidate marker genes for stasis are GYPA, RHAG, and ANK1; the candidate marker gene for deficiency is SLC2A1. The results help to reveal the biological connotations of phlegm, stasis, and deficiency in SONFH at the genetic level.

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.

Arthroscopic Femoral Head Allograft With Proximal Femoral/Periacetabular Osteotomies for Sequelae of Perthes: A Case Report.

CASE: We describe the unique case of a 20-year-old man with a history of Legg-Calve-Perthes disease, hip dysplasia, and osteochondral fragmentation of the medial femoral head. We performed arthroscopic femoroplasty and femoral head allografting, followed by a valgus-producing derotational femoral osteotomy (DFO) and periacetabular osteotomy (PAO). At 1-year follow-up, the patient achieved osseous union and complete femoral head healing with return to his active hobbies. CONCLUSION: We describe the successful utilization of arthroscopic allografting for medial femoral head osteochondral fragmentation. To our knowledge, this is the first report on femoral head arthroscopic allografting before DFO and PAO.

The influence of surgical technique guidance and surgeon's experience on the femoral head assembly in total hip arthroplasty.

INTRODUCTION: The importance of the assembly procedure on the taper connection strength is evident. However, existent surgical technique guides frequently lack comprehensive and precise instructions in this regard. The aim of our experimental study was to evaluate the influence of the surgical technique guide on the femoral head assembly procedure in surgeons with differing levels of experience in total hip arthroplasty. MATERIALS AND METHODS: Twenty-eight participants, divided into four groups based on their lifetime experience in total hip arthroplasty, conducted a femoral head assembly procedure in a simulated intraoperative environment before and after reviewing the surgical technique guide. Demographic information and the number of hammer blows were documented. Hammer velocity and impaction angle were recorded using an optical motion capturing system, while the impaction force was measured using a dynamic force sensor within the impactor. RESULTS: We observed a high variation in the number of hammer blows, maximum force, and impaction angle. Overall, the number of hammer blows decreased significantly from 3 to 2.2 after reviewing the surgical technique guide. The only significant intragroup difference in the number of hammer blows was observed in the group with no prior experience in total hip arthroplasty. No correlation was found between individual factors (age, weight, height) or experience and the measured parameters (velocity, maximum force and angle). CONCLUSIONS: The present study demonstrated a high variation in the parameters of the femoral head assembly procedure. Consideration of the surgical technique guide was found to be a limited factor among participants with varying levels of experience in total hip arthroplasty. These findings underline the importance of sufficient preoperative training, to standardize the assembly procedure, including impaction force, angle, and use of instruments.

Ganz femoral head reduction associated with coverage and containment procedures improve radiological and functional outcomes in Perthes' disease.

Aims: Ganz's studies made it possible to address joint deformities on both the femoral and acetabular side brought about by Perthes' disease. Femoral head reduction osteotomy (FHRO) was developed to improve joint congruency, along with periacetabular osteotomy (PAO), which may enhance coverage and containment. The purpose of this study is to show the clinical and morphological outcomes of the technique and the use of an implemented planning approach. Methods: From September 2015 to December 2021, 13 FHROs were performed on 11 patients for Perthes' disease in two centres. Of these, 11 hips had an associated PAO. A specific CT- and MRI-based protocol for virtual simulation of the corrections was developed. Outcomes were assessed with radiological parameters (sphericity index, extrusion index, integrity of the Shenton's line, lateral centre-edge angle (LCEA), Tönnis angle), and clinical parameters (range of motion, visual analogue scale (VAS) for pain, Merle d'Aubigné-Postel score, modified Harris Hip Score (mHHS), and EuroQol five-dimension five-level health questionnaire (EQ-5D-5L)). Early and late complications were reported. Results: The mean follow-up was 39.7 months (standard deviation (SD) 26.4). The mean age at surgery was 11.4 years (SD 1.6). No major complications were recorded. One patient required a total hip arthroplasty. Mean femoral head sphericity increased from 46.8% (SD 9.34%) to 70.2% (SD 15.44; p < 0.001); mean LCEA from 19.2° (SD 9.03°) to 44° (SD 10.27°; p < 0.001); mean extrusion index from 37.8 (SD 8.70) to 7.5 (SD 9.28; p < 0.001); and mean Tönnis angle from 16.5° (SD 12.35°) to 4.8° (SD 4.05°; p = 0.100). The mean VAS improved from 3.55 (SD 3.05) to 1.22 (1.72; p = 0.06); mean Merle d'Aubigné-Postel score from 14.55 (SD 1.74) to 16 (SD 1.6; p = 0.01); and mean mHHS from 60.6 (SD 18.06) to 81 (SD 6.63; p = 0.021). The EQ-5D-5L also showed significant improvements. Conclusion: FHRO associated with periacetabular procedures is a safe technique that showed improved functional, clinical, and morphological outcomes in Perthes' disease. The newly introduced simulation and planning algorithm may help to further refine the technique.

Non-traumatic osteonecrosis of the femoral head induced by steroid and alcohol exposure is associated with intestinal flora alterations and metabolomic profiles.

OBJECTIVE: Osteonecrosis of the femoral head (ONFH) is a severe disease that primarily affects the middle-aged population, imposing a significant economic and social burden. Recent research has linked the progression of non-traumatic osteonecrosis of the femoral head (NONFH) to the composition of the gut microbiota. Steroids and alcohol are considered major contributing factors. However, the relationship between NONFH caused by two etiologies and the microbiota remains unclear. In this study, we examined the gut microbiota and fecal metabolic phenotypes of two groups of patients, and analyzed potential differences in the pathogenic mechanisms from both the microbial and metabolic perspectives. METHODS: Utilizing fecal samples from 68 NONFH patients (32 steroid-induced, 36 alcohol-induced), high-throughput 16 S rDNA sequencing and liquid chromatography with tandem mass spectrometry (LC-MS/MS) metabolomics analyses were conducted. Univariate and multivariate analyses were applied to the omics data, employing linear discriminant analysis effect size to identify potential biomarkers. Additionally, functional annotation of differential metabolites and associated pathways was performed using the Kyoto Encyclopedia of Genes and Genomes (KEGG) database. Subsequently, Spearman correlation analysis was employed to assess the potential correlations between differential gut microbiota and metabolites. RESULTS: High-throughput 16 S rDNA sequencing revealed significant gut microbial differences. At the genus level, the alcohol group had higher Lactobacillus and Roseburia, while the steroid group had more Megasphaera and Akkermansia. LC-MS/MS metabolomic analysis indicates significant differences in fecal metabolites between steroid- and alcohol-induced ONFH patients. Alcohol-induced ONFH (AONFH) showed elevated levels of L-Lysine and Oxoglutaric acid, while steroid-induced ONFH(SONFH) had increased Gluconic acid and Phosphoric acid. KEGG annotation revealed 10 pathways with metabolite differences between AONFH and SONFH patients. Correlation analysis revealed the association between differential gut flora and differential metabolites. CONCLUSIONS: Our results suggest that hormones and alcohol can induce changes in the gut microbiota, leading to alterations in fecal metabolites. These changes, driven by different pathways, contribute to the progression of the disease. The study opens new research directions for understanding the pathogenic mechanisms of hormone- or alcohol-induced NONFH, suggesting that differentiated preventive and therapeutic approaches may be needed for NONFH caused by different triggers.

Exosomes derived from M2 macrophages prevent steroid-induced osteonecrosis of the femoral head by modulating inflammation, promoting bone formation and inhibiting bone resorption.

Inflammatory reactions are involved in the development of steroid-induced osteonecrosis of the femoral head(ONFH). Studies have explored the therapeutic efficacy of inhibiting inflammatory reactions in steroid-induced ONFH and revealed that inhibiting inflammation may be a new strategy for preventing the development of steroid-induced ONFH. Exosomes derived from M2 macrophages(M2-Exos) display anti-inflammatory properties. This study aimed to examine the preventive effect of M2-Exos on early-stage steroid-induced ONFH and explore the underlying mechanisms involved. In vitro, we explored the effect of M2-Exos on the proliferation and osteogenic differentiation of bone marrow-derived mesenchymal stem cells(BMMSCs). In vivo, we investigated the role of M2-Exos on inflammation, osteoclastogenesis, osteogenesis and angiogenesis in an early-stage rat model of steroid-induced ONFH. We found that M2-Exos promoted the proliferation and osteogenic differentiation of BMMSCs. Additionally, M2-Exos effectively attenuated the osteonecrotic changes, inhibited the expression of proinflammatory mediators, promoted osteogenesis and angiogenesis, reduced osteoclastogenesis, and regulated the polarization of M1/M2 macrophages in steroid-induced ONFH. Taken together, our data suggest that M2-Exos are effective at preventing steroid-induced ONFH. These findings may be helpful for providing a potential strategy to prevent the development of steroid-induced ONFH.

Time elapsed from definitive diagnosis to surgery for osteonecrosis of the femoral head: a nationwide observational study in Japan.

OBJECTIVES: This study documents the time elapsed from the diagnosis of osteonecrosis of the femoral head (ONFH) to surgery, exploring the factors that influence ONFH severity. DESIGN: Retrospective observational study of a nationwide database. SETTING: The Kaplan-Meier method with log-rank tests was applied to examine the period from definitive diagnosis of ONFH to surgery using any surgery as the end point. For bilateral cases, the date of the first surgery was the endpoint. PARTICIPANTS: This study included 2074 ONFH cases registered in 34 university hospitals and highly specialised hospitals of the multicentre sentinel monitoring system of the Japanese Investigation Committee between 1997 and 2018. MAIN OUTCOME MEASURE: The primary outcome was the time from diagnosis to surgery. The secondary outcome was the proportion of subjects remaining without surgery at 3, 6 and 9 months, and at 1, 2 and 5 years after diagnosis. RESULTS: The median time to surgery was 9 months (IQR 4-22 months) after diagnosis of ONFH. The time to surgery was significantly shorter in the alcohol alone group and the combined corticosteroid and alcohol group than in the corticosteroid alone group (p=0.018 and p<0.001, respectively), in early stage ONFH with no or mild joint destruction (stages II and III, p<0.001), and with joint preserving surgery (p<0.001). The proportion without surgery was 75.8% at 3 months, 59.6% at 6 months, 48.2% at 9 months, 40.5% at 1 year, 22.2% at 2 years and 8.3% at 5 years. CONCLUSION: ONFH has been considered to be an intractable disease that often requires surgical treatment, but the fact that surgery was performed in more than half of the patients within 9 months from diagnosis suggests severe disease with a significant clinical impact. TRIAL REGISTRATION NUMBER: Chiba University ID1049.

Investigational regenerative medicine for non-traumatic osteonecrosis of the femoral head: a survey of registered clinical trials.

INTRODUCTION: Osteonecrosis of the femoral head (ONFH) is a refractory disease requiring joint replacement in young patients. Regenerative therapies have been developed. AREAS COVERED: This study surveyed clinical trials on regenerative medicine for ONFH. We extracted clinical trials on non-traumatic ONFH from the websites of five publicly available major registries (EuropeanUnion Clinical Trials Register ([EU-CTR],ClinicalTrials.gov, Chinese ClinicalTrial Registry [ChiCTR], University Hospital Medical InformationNetwork - Clinical Trial Registry [UMIN-CTR] and Australian New Zealand Clinical Trials Registry [ANZCTR]).The trials were classified into six categories based on purpose: surgical treatment, non-drug conservative treatment, conservative drug treatment, therapeutic strategy, diagnosis and pathogenesis, and regenerative therapy.) We extracted 169 clinical trials on ONFH. Of these, 37 were on regenerative medicine, including 29 on cell therapy. Surgical treatment was the most common treatment, followed by regenerative therapy.There were 9 clinical trials registered in the EU-CTR, with 5 on regenerative medicine; 79 trials registered on ClinicalTrials.gov, with 24 on regenerativemedicine; 54 trials registered in the ChiCTR, with 6 on regenerative medicine. EXPERT OPINION: The focus of the joint-preserving surgery has shifted to regenerative therapy based on using cell therapy in early-stage ONFH. The global standardisation of regenerative therapy is still ongoing.

Femoral Head Core Decompressions: Characterization of Subsequent Conversion to Total Hip Arthroplasty and Related Complications.

BACKGROUND: Core decompression is a minimally invasive joint-preserving approach for early-stage osteonecrosis. The rate at which core decompression patients require total hip arthroplasty (THA) and rates of perioperative adverse outcomes have not been well-characterized. METHODS: Adult patients undergoing core decompression and/or THA with osteonecrosis of the femoral head were identified from the 2015 to 2021 Q3 PearlDiver M157 database. Those undergoing THA without or with antecedent core decompression were identified and matched 4:1 on age, sex, and Elixhauser Comorbidity Index. Postoperative 90-day adverse events were compared with multivariable analysis. Five-year rates of revision, dislocation, and periprosthetic fracture were compared by the Kaplan-Meier curve and log-rank tests. RESULTS: Core decompressions were identified for 3,025 patients of whom 387 (12.8%) went on to THA within 5 years (64% within the first year). The median time from initial core decompression to THA was 252 days. For THA, 26,209 adults were identified and 387 had prior core decompression. After matching, there were 1,320 without core decompression and 339 with core decompression. No statistically significant differences were observed in 90-day postoperative adverse events or 5-year rates of revision, dislocation, or periprosthetic fracture. CONCLUSION: Core decompression may be an option for patients with osteonecrosis and does not seem to affect THA outcomes if required later.