Does robotic-assisted computer navigation improve acetabular cup positioning in total hip arthroplasty for Crowe III/IV hip dysplasia? A propensity score case-match analysis.

AIMS: Total hip arthroplasty (THA) in patients with hip-dislocation dysplasia remains challenging. This study aims to evaluate whether these patients may benefit from robotic-assisted techniques. METHODS: We reviewed 135 THAs (108 conventional THAs and 27 robotic-assisted THAs) for Crowe type III or IV from January 2017 to August 2019 in our institution. Robotic-assisted THAs were matched with conventional THAs at a 1:1 ratio (27 hips each group) using propensity score matching. The accuracy of cup positioning and clinical outcomes were compared between groups. RESULTS: The inclination of the cup for conventional THAs and robotic THAs was 42.1 ± 5.7 and 41.3 ± 4.6 (p = 0.574), respectively. The anteversion of the cup for conventional THAs was significantly greater than that of robotic THAs (29.5 ± 8.1 and 18.0 ± 4.6; p < 0.001), respectively. The ratio of the acetabular cup in the Lewinnek safe zone was 37% (10/27) in conventional THAs and 96.3% (26/27) in robotic THAs (p < 0.001). Robotic THAs did not achieve better leg length discrepancy than that of conventional THAs (- 0.4 ± 10.9 mm vs. 0.4 ± 8.8 mm, p = 0.774). There was no difference in Harris Hip Score and WOMAC Osteoarthritis index between groups at the 2-year follow-up. No dislocation occurred in all cases at the final follow-up. CONCLUSION: Robotic-assisted THA for patients with high dislocation improves the accuracy of the implantation of the acetabular component with respect to safe zone.

Impact of negative-pressure wound therapy on bacterial behaviour and bioburden in a contaminated full-thickness wound.

The use of negative-pressure wound therapy (NPWT) has displayed significant clinical benefits in the healing of infected wounds. However, the effects of NPWT on bacterial colonisation and infection of traumatic wounds has been controversial. The aim of this study is to evaluate the impact of NPWT treatment in rabbits with a contaminated full-thickness wound on bacterial behaviour, including colony morphology, spatial distribution, fissional proliferation, and bacterial bioburden. Full-thickness wounds were created on the back of rabbits, and were inoculated with bioluminescent Staphylococcus aureus. The wounds were treated with sterile gauze dressings and NPWT with continuous negative pressure (-125 mm Hg). Wound samples were harvested on days 0 (6 hours after bacterial inoculation), 2, 4, 6, and 8 at the centre of wound beds before irrigation. Scanning electron microscopy and transmission electron microscopy (TEM) analyses were performed to determine the characteristic bacteriology. Laser scanning confocal microscopy was performed to obtain bioluminescent images, which were used to observe spatial distribution of the GFP-labelled S. aureus within the tissue and quantify the bacterial bioburden. NPWT resulted in sparse amounts of scattered bacteria on the wound surface or as sparsely spaced single colonies within the tissue. Wound bioburden on day 8 in the NPWT and gauze groups was 34.6 ± 5.5% and 141.9 ± 15.4% of the baseline values (N = 6), respectively (P < .0001). TEM showed a lack of S. aureus active fission within NPWT-treated tissue. NPWT can impact S. aureus colony morphology and spatial distribution both on the surface and within wound tissue, and reduce S. aureus as early as 48 hours after therapy initiation. Additionally, NPWT inhibits bacterial fissional proliferation in microcolonies.

[Preparation instructions for Experts consensus statement on Cheezheng Xiaotong Tiegao in clinical practice].

As a topical plaster developed by modern pharmaceutical technology based on traditional Tibetan medicine,Cheezheng Xiaotong Tiegao has functions of promoting blood circulation,relieving swelling and relieving pain. Since its introduction in 1993,it has been widely used in the treatment of various types of acute and chronic musculoskeletal pain and various types of spinal,joint and soft tissue diseases. In order to better standardize the clinical application and improve the clinical efficacy of Cheezheng Xiaotong Tiegao,the research and development work of the Experts consensus statement on Cheezheng Xiaotong Tiegao in clinical practice was officially launched on October 19,2017,upon approval from China Association of Chinese Medicine. In this paper,main R&D process and related technical links for the experts consensus on Cheezheng Xiaotong Tiegao would be summarized,which will help the various medical workers understand,master and apply more accurately,and also provide reference for the development of experts consensus on clinical application of other topical Chinese medicines.

Three-dimensional orientation and location-dependent varying rules of radiographic angles of the acetabular cup.

AIM: The aim of this study is to demonstrate the varying rules of radiographic angles following varying three-dimensional (3D) orientations and locations of cup using an accurate mathematical model. METHODS: A cone model is established to address the quantitative relationship between the opening circle of cup and its ellipse projection on radiograph. The varying rules of two-dimensional (2D) radiographic anteversion (RA) and inclination (RI) angles can be analyzed. RESULTS: When the centre of cup is located above X-ray source, with proper 3D RI/RA angles, 2D RA angle can be equal to its 3D counterpart, and 2D RI angle is usually greater than its 3D counterpart. Except for the original point on hip-centered anterior-posterior radiograph, there is no area on radiograph where both 2D RA and RI angles are equal to their 3D counterparts simultaneously. DISCUSSION: This study proposes an innovative model for accurately explaining how 2D RA/RI angles of cup are varying following different 3D RA/RI angles and location of cup. The analysis results provide clinicians an intuitive grasp of knowledge about 2D RA/RI angles greater or smaller than their 3D counterparts post-operatively. The established model may allow determining the effects of pelvic rotations on 2D radiographic angles of cup.

Correlation analysis of osteoporotic vertebral compression fractures and spinal sagittal imbalance.

PURPOSE: To evaluate the correlation between osteoporotic vertebral compression fractures and spinal sagittal imbalance, in order to provide a reference for clinical treatment. METHODS: From September 2013 to March 2015, 60 elderly patients with old osteoporotic vertebral compression factures (observation group) and 60 healthy elderly people (control group) were studied. Whole-spine anteroposterior and lateral view X­ray photographs were taken from all participants, the number and location of fractured vertebrae were recorded, and sagittal parameters in both groups were compared. The observation group was divided into three subgroups according to the number of fractured vertebrae. The C7/sacrofemoral distance (SFD) ratio in the three subgroups was compared, and the correlation between the number of fractured vertebrae and the C7/SFD ratio was analyzed. RESULTS: The thoracic kyphotic angle in patients in the observation group was higher than in the control group (P < 0.05), the lumbar lordotic angle in patients in the observation group was lower than in the control group (P < 0.05), the absolute value of the T1 spinopelvic inclination angle in patients in the observation group was lower than in the control group (P < 0.05), and the C7/SFD ratio of patients in the observation group was higher than in the control group (P < 0.05). C7/SFD ratios of the subgroups differed from each other, and the number of fractured vertebrae and C7/SFD ratio were positively correlated. CONCLUSION: Osteoporotic vertebral compression fractures can change local spinal sagittal alignment, multiple vertebral compression fractures can cause spinal sagittal imbalance, and the number of fractured vertebrae and the degree of forward movement of the spine were positively correlated.

Evaluation of Elastic Stiffness in Healing Achilles Tendon After Surgical Repair of a Tendon Rupture Using In Vivo Ultrasound Shear Wave Elastography.

BACKGROUND There has been no published report assessing the mechanical properties of a repaired Achilles tendon after surgery using shear wave elastography (SWE). The aim of this study was to investigate the changes in mechanical properties of the healing Achilles tendon after surgical repair of a tendon rupture using ultrasound SWE and how these changes correlate with tendon function. MATERIAL AND METHODS Twenty-six patients who underwent surgical repair for Achilles tendon rupture were examined with ultrasound SWE coupled with a linear array transducer (4-15 MHz). The elasticity values of the repaired Achilles tendon in a longitudinal view were measured at 12, 24, and 48 weeks postoperatively. Functional outcomes were assessed with the American Orthopedic Foot and Ankle Society (AOFAS) rating system at 12, 24, and 48 weeks postoperatively. General linear regression analysis and correlation coefficients were used to analyze the relationship between elasticity and the AOFAS score. RESULTS There were significant differences with respect to the mean elasticity values and functional scores of the repaired Achilles tendon at 12, 24, and 48 weeks postoperatively (all P<0.05). Tendon function was positively correlated with the elasticity of the repaired Achilles tendon (P=0.0003). CONCLUSIONS Our findings suggest that SWE can provide biomechanical information for evaluating the mechanical properties of healing Achilles tendon and predict Achilles tendon function.

Experimental study on treatment of acetabular anterior column fractures: applyment of a minimally invasive percutaneous lag screw guide apparatus.

BACKGROUND: The aim of this study was to design a new minimally invasive percutaneous lag screw guide apparatus and to verify its adjuvant treatment of acetabular anterior column fracture on pelvis specimens. METHODS: This guide apparatus was self-developed based on the principles of "two points form a line" and "Rectangle". Using C-arm fluoroscopy, this guide apparatus was used to conduct minimally invasive percutaneous lag screw internal fixation of acetabular anterior column fractures. Ten hollow lag screws were placed into 5 pelvis specimens. RESULT: Result showed no sign of any screws puncturing the cortex or entering into the hip joint on radiological assessment. The cross-section reconstructed vertical distance to the screw, on the cross-section acetabular notch and the cross-section of the screw where the distance of between the screw and the iliopectineal line's arc roof was at its shortest, indicate that at all points (T, R-r) under the line with an inclination of 1 (namely T = R-r) the screw is within the cortex and does not puncture the acetabula anterior column or enter into the hip joint. CONCLUSIONS: We may conclude that this self-developed guide apparatus solves the screw precision problem during the treatment of acetabular anterior column fractures through a minimally invasive percutaneous lag screw.

A computer aided measurement method for unstable pelvic fractures based on standardized radiographs.

BACKGROUND: To set up a method for measuring radiographic displacement of unstable pelvic ring fractures based on standardized X-ray images and then test its reliability and validity using a software-based measurement technique. METHODS: Twenty-five patients that were diagnosed as AO/OTA type B or C pelvic fractures with unilateral pelvis fractured and dislocated were eligible for inclusion by a review of medical records in our clinical centre. Based on the input pelvic preoperative CT data, the standardized X-ray images, including inlet, outlet, and anterior-posterior (AP) radiographs, were simulated using Armira software (Visage Imaging GmbH, Berlin, Germany). After representative anatomic landmarks were marked on the standardized X-ray images, the 2-dimensional (2D) coordinates of these points could be revealed in Digimizer software (Model: Mitutoyo Corp., Tokyo, Japan). Subsequently, we developed a formula that indicated the translational and rotational displacement patterns of the injured hemipelvis. Five separate observers calculated the displacement outcomes using the established formula and determined the rotational patterns using a 3D-CT model based on their overall impression. We performed 3D reconstruction of all the fractured pelvises using Mimics (Materialise, Haasrode, Belgium) and determined the translational and rotational displacement using 3-matic suite. The interobserver reliability of the new method was assessed by comparing the continuous measure and categorical outcomes using intraclass correlation coefficient (ICC) and kappa statistic, respectively. RESULT: The interobserver reliability of the new method for translational and rotational measurement was high, with both ICCs above 0.9. Rotational outcome assessed by the new method was the same as that concluded by 3-matic software. The agreement for rotational outcome among orthopaedic surgeons based on overall impression was poor (kappa statistic, 0.250 to 0.426). Compared with the 3D reconstruction outcome, the interobserver reliability of the formula method for translational and rotational measures was perfect with both ICCs more than 0.9. CONCLUSIONS: The new method for measuring displacement using a formula was reliable, and could minimise the measurement errors and maximise the precision of pelvic fracture description. Furthermore, this study was useful for standardising the operative plan and establishing a theoretical basis for robot-assisted pelvic fracture surgery based on 2-D radiographs.

Biomechanical Research of Three Parallel Cannulated Compression Screws in Oblique Triangle Configuration for Fixation of Femoral Neck Unstable Fractures.

OBJECTIVE: Surgical treatment with internal fixation, specifically percutaneous fixation with three cannulated compression screws (CCSs), is the preferred choice for young and middle-aged patients. The mechanical advantage of the optimal spatial configuration with three screws provides maximum dispersion and cortical support. We suspect that the spatial proportion of the oblique triangle configuration (OTC) in the cross-section of the femoral neck isthmus (FNI) may significantly improve shear and fatigue resistance of the fixed structure, thereby stabilizing the internal fixation system in femoral neck fracture (FNF). This study aims to explore the mechanical features of OTC and provide a mechanical basis for its clinical application. METHODS: Twenty Sawbone femurs were prepared as Pauwels type III FNF models and divided equally into two fixation groups: OTC and inverted equilateral triangle configuration (IETC). Three 7.3 mm diameter cannulated compression screws (CCSs) were used for fixation. The specimens of FNF after screw internal fixation were subjected to static loading and cyclic loading tests, respectively, with five specimens for each test. Axial stiffness, 5 mm failure load, ultimate load, shear displacement, and frontal rotational angle of two fragments were evaluated. In the cyclic loading test, the load sizes were 700 N, 1400 N, and 2100 N, respectively, and the fracture end displacement was recorded. Results were presented as means ± SD. Data with normal distributions were compared by the Student's t test. RESULTS: In the static loading test, the axial stiffness, ultimate load, shear displacement, and frontal rotational angle of two fragments were (738.64 vs. 620.74) N/mm, (2957.61 vs. 2643.06) N, (4.67 vs. 5.39) mm, and (4.01 vs. 5.52)° (p < 0.05), respectively. Comparison between the femoral head displacement after 10,000 cycles of 700N cyclic loading and total displacement after 20,000 cycles of 700-1400N cyclic loading showed the OTC group was less than the IETC group (p < 0.05). A comparison of femoral head displacement after 10,000 cycles of 1400N and 2100N cycles and total displacement after 30,000 cycles of 700-2100N cycles showed the OTC group was less than another group, but the difference was not significant (p > 0.05). CONCLUSION: When three CCSs are inserted in parallel to fix FNF, the OTC of three screws has obvious biomechanical advantages, especially in shear resistance and early postoperative weight-bearing, which provides a mechanical basis for clinical selection of ideal spatial configuration for unstable FNF.

[Biological changes after axonal stretch and their mechanisms].

Research on peripheral nervous injuries, especially the stretched injuries, is important to improve the clinical effectiveness and alleviate the patients's pain. In recent years, the biological changes and mechanics of stretched axons have been hot topics. This article reviews the recent advances in the morphological changes of axons as well as changes in cellular membrane, cytoskeleton, cellular metabolism, and action potential after axonal stretch.

Intramedullary nailing versus plating fixation for the treatment of midshaft clavicular fractures: A meta-analysis of randomized controlled trials.

PURPOSE: This study was to test the hypothesis that intramedullary (IM) nailing fixation of midshaft clavicle fractures could result in better clinical outcomes and lower complications rates than plating fixation. METHODS: PubMed, Embase, and the Cochrane Library database were used to search all English language published randomized controlled trials (RCTs) of midshaft clavicle fractures using plating versus IM nailing. The characteristics of the study participants were collected. Outcomes of postoperative shoulder functional measurements, operative data and complications rates were meta-analyzed. RESULTS: Eight hundred and ninety-five patients in ten RCTs and three quasi-RCTs were involved in the meta-analysis. The results of meta-analysis of these studies showed that the functional outcome evaluated by the Constant Shoulder and Disabilities of the Arm, Shoulder and Hand (DASH) scores after accepting IM nailing was significantly better than that of plating fixation at one year post-operatively (P < 0.01), with the heterogeneity of 43% and 91%, respectively. Sensitivity analyses of the pooled results of Constant and DASH scores displayed that the functional advantage of IM nailing fixation comes from the subgroup of locked IM nailing. Further, regarding the operative statistics, operative time, blood loss and wound length were significantly less in the IM nailing group than the plating group (P < 0.001). The rates of infection, major complications and complications-related revision surgery were significantly higher in the plating group than the IM nailing group; however, there were no significantly statistical differences in other complications, e.g., nonunion, refracture after hardware removal, implant failure, symptomatic hardware, etc. (P > 0.05). CONCLUSION: The observations in this review suggested that IM nailing, especially locked IM nailing, could provide better shoulder functional outcome at one-year follow-up. Moreover, IM nailing fixation could effectively reduce operative time, blood loss, rates of infection, major complications, and revision surgery than plating. Further high-quality clinical trials with large samples and consistent designs are still needed to verify the long-term functional advantage of locked and unlocked IM nailing for midshaft clavicle fractures. LEVEL OF EVIDENCE: Level II.

Gradual Traction Reduction With the Ilizarov Method for Tile C1.2 Old Pelvic Fracture: A Case Report.

CASE: A 20-year-old man with a Tile C1.2 pelvic fracture was treated with skeletal traction. After 3 months, the patient was unable to stand and walk, and the right lower limb was shortened by 7 cm. Radiographs showed that the sacroiliac joint dislocation was not reduced. Gradual traction reduction with the Ilizarov method was used to correct sacroiliac joint dislocation, and open internal fixation was performed. Postoperatively, the old pelvic fracture was successfully reduced without sacral plexus injury. CONCLUSION: Gradual traction reduction with the Ilizarov method can reduce the risk of sacral plexus injury and achieve satisfactory reduction of Tile C1.2 old pelvic fractures.

Negative pressure promotes macrophage M1 polarization after Mycobacterium tuberculosis infection via the lncRNA XIST/microRNA-125b-5p/A20/NF-κB axis.

Experiments have demonstrated the regulation of long noncoding RNA (lncRNA) in tuberculosis (TB), and negative pressure treatment has been associated with the alleviation of TB. Here, we investigated the interaction of negative pressure and the lncRNA X-inactive specific transcript (XIST) in modulating Mycobacterium tuberculosis (MTB) infection. Initially, we established an in vitro cell model of MTB infection and an in vivo mouse model of MTB infection, followed by treatment with negative pressure. Then, we examined the expression of XIST, followed by analysis of the downstream miRNA of XIST. XIST was overexpressed or underexpressed through cell transfection to examine its effects on macrophage polarization via the miR-125b-5p/A2 axis. The MTB models were characterized by upregulated XIST and downregulated miR-125b-5p. XIST bound to miR-125b-5p, leading to its downregulation, and thus causing higher MTB survival in an ESAT-6-dependent manner. Additionally, negative pressure treatment decreased MTB-driven XIST expression through downregulation of A20 (an NF-κB repressor) via miR-125b-5 expression, promoting the M1 polarization program in macrophages through activation of the NF-κB pathway. In summary, negative pressure treatment after MTB infection can promote the polarization of macrophages to the proinflammatory M1 phenotype by regulating the XIST/miR-125b-5p/A20/NF-κB axis.

The oblique triangle configuration of three parallel screws for femoral neck fracture fixation using computer-aided design modules.

Closed reduction and internal fixation with three cannulated compression screws is a common method for treating femoral neck fractures in young and middle-aged patients. Protocols including the inverted triangle configuration and dispersion of the screws still needed further supports. The purpose of this study was to explore a novel oblique triangle configuration (OTC) of three screws in fixing femoral neck fractures based on the morphology of the femoral neck isthmus (FNI). The computer-aided design modules were used to explore the ideal spatial configuration with largest triangle by three parallel screws. A univariate evaluation model was established based on the oval-like cross-section of the FNI. When the three screws were positioned by the OTC, Inverted Equilateral Triangle Configuration (IETC), and the Maximum Area Inverted Isosceles Triangle Configuration (MA-IITC) respectively, the proportion of area and circumference in the cross-section of FNI and the changing trend of proportion were compared under various torsion angles, eccentricity, and cross-sectional area of FNI. The area and circumference ratios of the parallel screws using the OTC method were significantly higher than in the IETC and MA-IITC groups. In the univariate evaluation model, the OTC area ratio and circumference ratio remained stable under the different femoral neck torsion angles, FNI cross-sectional area, and eccentricity. The OTC method provided an ideal spatial configuration for the FNA fixation with the largest area using three parallel screws. The position of the posterior screw was also away from the metaphyseal artery, potentially reducing the possibility of vascular injury and screw penetrating.

Comparison of oblique triangular configuration and inverted equilateral triangular configuration of three cannulated screws in treating unstable femoral neck fracture: A finite element analysis.

BACKGROUND: The cross-sectional area of three parallel screws might affect the stability of the internal fixation of femoral neck fractures. The screws fixed in the oblique-triangle configuration (OTC) were assumed to have a larger cross-sectional area, but the biomechanical stability has not yet been validated. In this study, finite element analyses were performed to compare the biomechanical properties of the internal fixation fixed by the OTC and the traditional Inverted Equilateral Triangle Configuration (IETC). METHOD: Pauwels type III fracture was established on the three-dimensional femoral model and three cannulated screws with the OTC and traditional IETC methods were applied. The oblique-triangle configuration with the largest area inscribed the femoral neck isthmus by the three screws was determined, the area and circumference of the cross-section formed by the OTC and IETC model were compared. Stress, strain, and displacement peaks of the two configuration models under different loads were compared. Twelve pairs of nodes on the fracture ends were selected and the displacement of the fracture ends was evaluated through the displacement between these nodes. RESULTS: The area and circumference of the cross-section formed by the OTC were larger than those in the IETC model. The degree of stress dispersion around the screw holes in the OTC model was better than that of the IETC, but the stress distribution order of the three screws in the two models was consistent. The maximum stress, strain, displacement, and displacement of the fracture end in the OTC model were smaller than those in the IETC model. The stress, strain, displacement, and fracture end displacement peaks of the two fixed models gradually increase with the increase of loads. CONCLUSION: The oblique-triangle configuration showed superior mechanical properties than the IETC in finite element analyses. This study suggests that when three screws are fixed in parallel method, the larger the cross-sectional area of the screw configuration, the better stability of the internal fixation might be obtained. Furthermore, the biomechanical properties of various spatial configurations and screw holes of the three parallel screws need to be considered before clinical practice.

rhBMP-2 not alendronate combined with HA-TCP biomaterial and distraction osteogenesis enhance bone formation.

INTRODUCTION: The long treatment duration of distraction osteogenesis (DO) usually causes some complications such as re-fracture, non-union. We have previously demonstrated that the combined use of biomaterial with distraction osteogenesis technique can enhance bone formation and consolidation. This study further tested whether the use of biological agents such as rhBMP-2 or alendronate together with biomaterials in DO will further promote bone formation. METHODS: A 1.0-cm tibial shaft was removed in the left tibia of 30 rabbits. The 1.0-cm defect gap was reduced to 0.5 cm and the remaining 0.5-cm defect gap was filled with 0.5-cm restorable hydroxyapatite/tri-calcium phosphates (HA/TCP) cylindrical block. The animals were divided into three groups with the following added on the HA/TCP block: Group A 50 µl of saline, Group B 75 µg rhBMP-2 in 50 µl of saline, Group C 250 µg alendronate in 50 µl saline. The tibia was then fixed with unilateral lengthener and lengthening started 7 days after at a rate of 1.0 mm/day for 5 days. All animals were terminated at day 37 following surgery. The excised bone specimens were subject to micro-CT, mechanical testing and histological examinations. RESULTS: Bone mineral density and content were significantly higher in Groups A and B compared to Group C and the mechanical properties of the regenerates in Group B were highest. Micro-CT and histological examinations also confirmed that the regenerates in Group B had the most advanced bone formation, consolidation and remodeling comparing to other groups. CONCLUSION: The combined use of rhBMP-2 with HA-TCP biomaterial in DO has significantly enhanced bone formation and consolidation than using the HA-TCP biomaterials alone, whereas the use of alendronate has inhibitory effects on bone formation.

[Properties evaluation of collagen-hydroxyapatite-chondroitin sulfate-bone morphogenetic protein bone substitute material].

OBJECTIVE: To construct a new 3D porous bone substitute material with collagen, hydroxyapatite and chondroitin sulfate, which has the main components of nature bone and the cell growth factor BMP-2 with bone inductive ability. METHODS: Collagen-hydroxyapatite-chondroitin sulfate scaffolds were prepared by chemical cross linking and freeze-drying, and bone morphogenetic protein (BMP) was incorporated into the scaffolds by adsorption. The bone substitute material was investigated by HE analysis, scanning electron microscope(SEM), electron spectroscopy for chemical analysis(ESCA), and X-ray diffraction(XRD). Rat mesenchymal stem cells (MSCs) were seeded into the scaffolds and cultured to form cell/scaffold (CS) constructs in vitro. The ectopic osteoinduction of the scaffolds were evaluated in vivo. RESULTS: The bone substitute material had a porous 3D structure facilitating cells growing into it. Implanted into the muscle, the scaffolds were degraded with the forming of new bone. CONCLUSION: Our Findings indicate that the bone substitute material has good biocompatibility and its attachment to CS could improve the adhesion and differentiation of cells.

The Oval-like Cross-section of Femoral Neck Isthmus in Three-dimensional Morphological Analysis.

OBJECTIVES: To investigate the cross-section shape of the femoral neck isthmus (FNI) in three-dimensional reconstruction model of the femoral neck. METHODS: From December 2009 to December 2012, computed tomography (CT) data of bilateral hip joint from 200 consecutive patients (137 males and 63 females, 69.41 ± 9.21 years old, ranged from 50-85 years old) who underwent surgical treatments for proximal femoral fracture were retrospectively reviewed. The 3D model of the proximal femur was reconstructed, and the "inertia axis" method, which was applied to measure the long and short axes of the cross-section of the FNI, was established. The cross-sectional area and perimeter were calculated by a formula using the length of the long and short axes and then compared with the actual measured values by the software. Correlation between the descriptive parameters of the FNI cross-section (area, perimeter, and eccentricity) and patients' demographics (age, height, and weight) was analyzed. Stepwise linear regression analysis was used to determine the main relevant factors. RESULTS: The ICC results showed excellent data reproducibility ranged from 0.989 to 0.996. There was no significant difference in the cross-sectional area of the FNI between the actual measured values and the predicted values using the formula (732.83 ± 126.74 mm2 vs 731.62 ± 128.15 mm2 , P = 0.322). The perimeter using the two methods showed narrow while significant difference (97.86 ± 8.60 mm vs 92.84 ± 8.65 mm, P < 0.001), the actual measured values were about 5 mm greater than the predicted values. The parameters (area, perimeter, and eccentricity) were significantly larger in male than female (P < 0.001). A positive correlation between the cross-sectional area, perimeter, height, and weight was observed. The stepwise linear regression analysis showed that the regression equation of the FNI area was as follows: Y = -1083.75 + 1033.86 × HEIGHT + 1.92 × WEIGHT, R2 = 0.489. CONCLUSION: The cross-section shape of the FNI appears to be oval-like in the 3D model, which is separated according to the inertia axis, and the findings proposed an anatomical basis for the further study of the spatial configuration of cannulated screws in the treatment of femoral neck fractures.