Proximal Femur Bionic Nail (PFBN): A Panacea for Unstable Intertrochanteric Femur Fracture

With the aging population,intertrochanteric femur fracture in the elderly has become one of the most serious public health issues and a hot topic of research in trauma orthopedics.Due to the limitations of internal fixation techniques and the insufficient mechanical design of nails,the occurrence of complications delays patient recovery after surgical treatment.Design of a proximal femur bionic nail(PFBN)based on Zhang’s N triangle theory provides triangular supporting fixation,which dramatically decreases the occurrence of complications and has been widely used for clinical treatment of unstable intertrochanteric femur fracture worldwide.In this work,we developed an equivalent biomechanical model to analyze improvement in bone remodeling of unstable intertrochanteric femur fracture through PFBN use.The results show that compared with proximal femoral nail antirotation(PFNA)and InterTan,PFBN can dramatically decrease the maximum strain in the proximal femur.Based on Frost’s mechanostat theory,the local mechanical environment in the proximal femur can be regulated into the medium overload region by using a PFBN,which may render the proximal femur in a state of physiological overload,favoring post-operative recovery of intertrochanteric femur fracture in the elderly.This work shows that PFBN may constitute a panacea for unstable intertrochanteric femur fracture and provides insights into improving methods of internal fixation.

Clinical and functional comparison of dynamic hip screws and intramedullary nails for treating proximal femur metastases in older individuals

Objective:To compare the outcomes of dynamic hip screws(DHS)and intramedullary nailing(IMN)in the treatment of extra-capsular metastatic carcinoma of the proximal femur.Methods:A retrospective case analysis method was used to examine data of patients with proximal metastatic cancer of the femur who were treated with internal fixation in Department of Orthopaedics,Beijing Friendship Hospital,from January 2007 to December 2018.Blood loss,postoperative pain,functional score,length of stay,and survival rates were compared,and postoperative complications were assessed.Results:Complete follow-up data were available for 33 patients.The mean follow-up period was 12.2±3.6(range:9-32)months and the average age was 72.3±4.7(range:59-83)years old.There were 20 females and 13 males.Twenty-three patients had undergone IMN and 10 DHS,according to bone defects and the patient’s overall condition.The median survival time was 10 months in the IMN group and 11 months in the DHS group.Duration of surgery(t=-7.366,P<0.001)and length of hospital stay(t=-3.509,P<0.001)differed significantly between the two groups.There was one case of breakage of internal fixation in the IMN group.Conclusions:There was no significant difference between DHS and IMN in terms of surgical efficacy.IMN and DHS were different in terms of surgical time and hospital stay.However,due to the limited number of cases in this study,multi-factor analysis has not been performed and needs to be further verified in future analysis.When developing a surgical plan,it is recommended to consider the patient’s condition and the surgeon’s experience.

Clinical and functional comparison of endoprosthetic replacement with intramedullary nailing for treating proximal femur metastasis

Objective： To evaluate the clinical and functional outcomes of modular endoprosthetic replacement （EPR） compared to proximal femur intramedullary nailing （IMN） for the treatment of proximal femur metastases. Methods： We retrospectively studied the records of patients with proximal femur metastatic lesions treated with surgical stabilization between January 2007 and December 2014 in terms of operation time, blood loss, postoperative score, soreness, Karnofsky performance score （KPS） and survival time. Results： There were 34 patients treated with surgical stabilization. The mean follow-up period was 12.1~8.6 months （range： 10-47 months）. Thirteen were treated with EPR and 21 were stabilized with IMN （20 males, 14 females; mean age： 68.7 years）. The median survival time was 11.0 months for both groups （P=0.147）. The operation time, blood loss and Harris score of IMN group were lower than those of EPR group （P=0.001, P=0.001, P=0.002, respectively）. Conclusions： Both EPR and IMN for treating proximal femur metastasis achieved effective clinical outcomes. Therefore, the suitable surgical methods depended on the general conditions and medical requirements of patients, as well as the technical advantages of the doctor.

Effect of proximal femur nail anti-rotation on unstable intertrochanteric fractures: A prospective observational study

Objective:To assess the effect of proximal femur nail anti-rotation on the functional and radiological outcome of unstable intertrochanteric fractures.Methods:This prospective observational study was conducted in the orthopedic department of a tertiary care hospital.Altogether 86 patients with unstable intertrochanteric fractures treated with proximal femur nail anti-rotation between January 2010 and January 2015 were included.Patients were followed in the outpatient clinic at regular intervals after discharge to assess the radiological union of fractures and complications.The functional outcomes were evaluated after 2 years by Harris hip score.Results:All patients achieved a radiological union of fractures after a mean duration of 24.6 weeks.The follow up showed 23 complications(systemic and local).Eight patients developed urinary tract infections,and three patients developed chest infections,two patients had screw cut-out,one patient had knee stiffness,one patient developed superficial surgical site infection,and four patients developed varus collapse and shortening subsequently.The two year follow up showed that 69(80.2%)patients had an excellent and good functional outcome according to Harris hip score.Conclusions:With lower complication rates,proximal femur nail is a valid and reasonable option especially in treating unstable intertrochanteric fractures.

Numerical Simulation of Bone Remodeling Coupling the Damage Repair Process in Human Proximal Femur

Microdamage is produced in bone tissue under the long-termeffects of physiological loading,as well as age,disease and other factors.Bone remodeling can repair microdamage,otherwise this damage will undermine bone quality and even lead to fractures.In this paper,the damage variable was introduced into the remodeling algorithm.The new remodeling algorithm contains a quadratic term that can simulate reduction in bone density after large numbers of loading cycles.The model was applied in conjunction with the 3Dfinite elementmethod(FEM)to the remodeling of the proximal femur.The results showed that the initial accumulation of fatigue damage led to an increase in density but when the damage reached a certain level,the bone density decreased rapidly until the femur failed.With the accumulation of damage,bone remodeling was coupled with fatigue damage to maintain the function of bone.When the accumulation of damage reached a certain level,bone remodeling failed to repair the accumulated fatigue damage in time,and continued cyclic loading significantly weakened the loadbearing capacity of the bone.The new mathematical model not only predicts fatigue life,but also helps to further understand the compromise between damage repair and damage accumulation,which is of great significance for the prevention and treatment of clinical bone diseases.

Application of proximal femur locking compression plate for unstable four part intertrochanteric fractures

Objective To evaluate the clinical results of proximal femur locking compression plate (LCP) for unstable four-part intertrochanteric femoral fractures.Methods Clinical data of53patients wiith unstable four-part intertrochanteric

Finite Element Analysis of Coronal Shear Fractures of the Femoral Neck: Displacement of the Femoral Head and Effect of Osteosynthetic Implants

Coronal shear fractures of the femoral neck (CSFF) are the most challenging to treat among proximal femur fractures, directly affecting the life expectancy of patients with osteoporosis. However, an adequate osteosynthesis method has not been elucidated yet. This study investigated the displacement direction of the femoral head fragment and its effect on the bone using finite element method. A finite element model for CSFF was developed from CT image data of a patient with osteoporosis using Mechanical Finder (ver. 11). Subsequently, finite element analyses were performed on six osteosynthesis models under maximum load applied during walking. The compressive stresses, tensile stresses, and compressive strains of each model were examined. The results suggested that the compressive and tensile stress distributions were concentrated on the anterior side of the femoral neck. Compressive strain distribution in the femoral head and neck was concentrated in four areas: at the tip of the blade or lag screw, the anteroinferior side of the blade or lag screw near the fracture site, and the upper right and lower left near the junction of the blade or lag screw and nail. Thus, the distribution of both these stresses revealed that the femoral head fragment was prone to anterior and inferior displacement. Distribution of compressive strains revealed the direction of the stress exerted by the osteosynthetic implant on the bone. The same results were observed in all osteosynthetic implants;thus, the findings could lay the foundation for developing methods for placing osteosynthetic implants less prone to displacement and the osteosynthetic implants themselves. In particular, the study provides insight into the optimal treatment of CSFF.

Risk modeling of femoral neck fracture based on geometric parameters of the proximal epiphysis

BACKGROUND Fractures of the proximal femur epiphysis are problematic for state health care because they are associated with severe medical and social problems and high morbidity and mortality rates.AIM To model the potential risk of hip fracture via femur geometric parameters.METHODS Seventy educational cadaveric femurs from people aged 14 to 80 years,10 X-ray images from the records of the Human Anatomy Department and 10 X-ray images from the Department of Traumatology,Orthopedics and Disaster Surgery of Sechenov University,were evaluated.The parameters of the fractured bone were measured using images captured with a Canon d60 camera.The projection values of the proximal epiphysis of the cadaveric femurs and geometric parameters of the bones shown in the X-ray images were measured with Autodesk software(AutoCAD 2018).Analysis of the video frames showing bone rotation reveal that the greater trochanter can be inscribed in a parallelepiped,where one of the faces is parallel to the plane of view in the frontal standard projection and is rectangular.The angle of bone rotation obtained by turning the cube corresponded to the angle measured with the second technique.This reliable method of calculating the rotation of the bone relative to the anterior projection was employed in subsequent calculations.The geometric parameters of the femur were measured using X-ray images according to the proposed method.RESULTS The geometric parameters of 70 femurs were analyzed,and correlation coefficients were calculated.Our measurement results were compared with those reported by other authors.The potential influence of femur geometry on force distribution in the proximal epiphysis of the femur was described,and a 2-dimensional model of the femur epiphysis associated with minimal neck fracture risk was provided.The assessment of the geometric parameters of the femoral epiphysis indicated the greatest risk of a varus fracture of the neck if the angle of the minimal resistance zone(AMRZ)index>24°and the neck-shaft angle(NSA)<127.5°.In contrast,the minimum risk was observed at AMRZ<14°and NSA>128.87°.CONCLUSION The proposed method provides the potential femur neck fracture risk based on geometric parameters.

Total hip arthroplasty following the failure of intertrochanteric nailing:First implant or salvage surgery?

BACKGROUND Proximal femur fractures,including both intracapsular(femoral neck fractures)and extracapsular fractures(intertrochanteric femoral fractures,IFFs),affect around 1.5 million people per year worldwide.Mechanical failures of intertrochanteric nailing in IFFs could be managed with revision total hip arthroplasty(THA).AIM To describe the surgical complexity and the procedure-related complication rates in patients with trochanteric nailing failure and treated with THA.METHODS Patients referred to our level I trauma center between April 2012 and July 2018 with failed cephalomedullary nailing following trochanteric fractures were retrospectively recruited.All patients underwent a salvage surgical procedure,i.e.,cephalomedullary nail removal and conversion to THA.The same surgical and anesthesiology team performed the surgical procedures under spinal anesthesia.All patients underwent clinical and radiographic follow-ups for at least 24 mo.Complications and re-operations were recorded.RESULTS Seventy-four patients met the inclusion criteria(male:29;female:45;mean age:73.8-years-old;range:65-89)and were included in the current study.The average operative time was 117 min(76-192 min).The average blood loss was 585 mL(430-1720 mL).Among the 74 patients,43(58.1%)required transfusion of three or more blood units.Two patients died within the 4th d after surgery because of pulmonary embolism,and 1 patient died 9 mo after surgery due to ischemic myocardial infarction.The complication rate in the 71 patients who completed the minimum 24-mo follow-up was 22.5%.In 3 cases out of 71(4.2%)periprosthetic acetabular fracture was observed during the followup.One of these periacetabular fractures occurred intraoperatively.An intraoperative periprosthetic femur fracture was observed in 5 patients out of 71(7.0%).Four of these patients needed a re-operation to fix the fracture with plates and cerclages;in one of these patients,femoral stem revision was also necessary.In 4 patients out of 71(5.6%),an early THA dislocation was observed,whereas in 1 case(1.4%)a late THA dislocation was observed.Three patients out of 71(4.2%)developed a periprosthetic joint infection during the study follow-up.CONCLUSION The present study demonstrated that salvage options for IFF fixation failure are complex procedures with a relevant intraoperative and postoperative complication rate.

Bone mineral density in lifelong trained male football players compared with young and elderly untrained men

Purpose: The purpose of the present controlled cross-sectional study was to investigate proximal femur and whole-body bone mineral density(BMD), as well as bone turnover profile, in lifelong trained elderly male football players and young elite football players compared with untrained age-matched men.Methods: One hundred and forty healthy, non-smoking men participated in the study, including lifelong trained football players(FTE, n = 35)aged 65—80 years, elite football players(FTY, n = 35) aged 18—30 years, as well as untrained age-matched elderly(UE, n = 35) and young(UY,n = 35) men. All participants underwent a regional dual-energy X-ray Absorptiometry(DXA) scan of the proximal femur and a whole-body DXA scan to determine BMD. From a resting blood sample, the bone turnover markers(BTMs) osteocalcin, carboxy-terminal type-1 collagen crosslinks(CTX-1), procollagen type-1 amino-terminal propeptide(P1NP), and sclerostin were measured.Results: FTE had 7.3%—12.9% higher(p < 0.05) BMD of the femoral neck, wards, shaft, and total proximal femur in both legs compared to UE,and 9.3%—9.7% higher(p < 0.05) BMD in femoral trochanter in both legs compared to UY. FTY had 24.3%—37.4% higher(p < 0.001) BMD in all femoral regions and total proximal femur in both legs compared to UY. The whole-body DXA scan confirmed these results, with FTE showing similar whole-body BMD and 7.9% higher(p < 0.05) leg BMD compared to UY, and with FTY having 9.6% higher(p < 0.001) wholebody BMD and 18.2% higher(p < 0.001) leg BMD compared to UY. The plasma concentration of osteocalcin, CTX-1, and P1NP were 29%,53%, and 52% higher(p < 0.01), respectively, in FTY compared to UY.Conclusion: BMD of the proximal femur and whole-body BMD are markedly higher in lifelong trained male football players aged 65—80 years and young elite football players aged 18—30 years compared to age-matched untrained men. Elderly football players even show higher BMD in femoral trochanter and leg BMD than untrained young despite an age difference of 47 years.

A Femur-Implant Model for the Prediction of Bone Remodeling Behavior Induced by Cementless Stem

Bone remodeling simulation is an effective tool for the prediction of long-term effect of implant on the bone tissue, as well as the selection of an appropriate implant in terms of architecture and material. In this paper, a finite element model of proximal femur was developed to simulate the structures of internal trabecular and cortical bones by incorporating quantitative bone functional adaptation theory with finite element analysis. Cementless stems made of titanium, two types of Functionally Graded Material （FGM） and flexible ＇iso-elastic＇ material as comparison were implanted in the structure of proximal femur respectively to simulate the bone remodeling behaviors of host bone. The distributions of bone density, von Mises stress, and interface shear stress were obtained. All the prosthetic stems had effects on the bone remodeling behaviors of proximal femur, but the degrees of stress shielding were different. The amount of bone loss caused by titanium implant was in agreement with the clinical obser- vation. The FGM stems caused less bone loss than that of the titanium stem, in which FGM I stem （titanium richer at the top to more HAP/Col towards the bottom） could relieve stress shielding effectively, and the interface shear stresses were more evenly distributed in the model with FGM 1 stem in comparison with those in the models with FGM II （titanium and bioglass） and titanium stems. The numerical simulations in the present study provided theoretical basis for FGM as an appropriate material of femoral implant from a biomechanical point of view. The next steps are to fabricate FGM stern and to conduct animal experiments to investigate the effects of FGM stem on the remodeling behaviors using animal model.

Regional Variations in Trabecular Morphological Features of Femoral Head of Patients with Proximal Femoral Fractures

The regional microstructural variations in femoral head from proximal femoral fracture patients were investigated. Mi- cro-CT scanning was performed on seven femoral heads from proximal femoral fracture patients. Each femoral head was divided into three regions according to the trabecular orientation from the fovea of femoral head to the femoral neck. Eight three-dimensional trabecular cube models were reconstructed from each region. A total of 154 trabecular cubic models were reconstructed because the corresponding areas for 14 cubic models were damaged during the surgeries. Eight trabecular mor- phological parameters were measured and analyzed, namely, trabecular thickness （Tb.Th）, trabecular separation （Tb.Sp）, spe- cific bone surface （BS/BV）, bone volum在不 fraction （BV/TV）, structural model index （SMI）, degree of anisotropy （DA）, trabecular pattern factor （Tb.Pf）, and trabecular number （Tb.N）. Bivariate correlation analyses were performed for all mor- phological parameters. One-way ANOVA tests were performed to analyze the differences of each parameter among three re- gions. Post-hoc multiple comparisons （Student-Newman-Keuls method） were performed to analyze the morphological differ- ence between two regions. Trabecular bone of proximal femoral fracture patients significantly degenerated in all regions of femoral heads. BV/TV was statistically correlated with Tb.Th, Tb.Sp, BS/BV, Tb.Pf, and Tb.N （p 〈 0.05）. Statistical differences in morphological parameters were observed between regions （p 〈 0.05）. The trabecular strength in the middle regions was significantly higher than that in other regions because of the relationships between morphological parameters and mechanical parameters. Trabeculae in the medial region were more uniform and stable along each direction than those in the lateral region. Most trabeculae in the lateral region only grew along the weight-bearing direction, and those along the other directions de- generated significantly. This study provides detailed trabecular morphological information on fractured femoral heads, as well as references for the prevention of high fracture risk in the elderly.