Optimizing Stability in Femoral Neck Fracture Fixation

Comparison of femoral neck shortening after femoral neck system and cannulated cancellous screw fixation for displaced femoral neck fractures in young adults

BACKGROUND

The purpose of this study was to compare the outcomes of femoral neck shortening between the femoral neck system (FNS) and the cannulated cancellous screws (CCS) for displaced femoral neck fractures in young adults PATIENTS AND METHODS: In this retrospective analysis, 225 patients aged 18-65 years with displaced femoral neck fracture were divided into two groups according to internal fixation: 135 patients in the FNS group and 90 patients in the CCS group. The length of hospital stay, duration of surgery, intraoperative blood loss, quality of reduction, extent of femoral neck shortening, incidence of femoral neck shortening, femoral neck shortening at each follow-up visit, Harris hip score (HHS), reoperation, and complications were compared between the two groups.

RESULTS

The median follow-up time was 28.2 (26.0, 31.2) months in the FNS group and 30.2 (26.3, 34.7) months in the CCS group. The follow-up time, age, sex distribution, body mass index (BMI), mechanism of injury, injured side, length of hospital stay, time from injury to surgery, and fracture classification were similar between the groups. Duration of surgery was longer in the FNS group (65.0 (55.0, 87.0) min versus 55.0 (50.0, 65.0) min, P<0.001); intraoperative blood loss was greater in the FNS group (50.0 (20.0, 60.0) ml versus 20.0 (10.0, 35.0) ml, P<0.001). Femoral neck shortening was 2.4 (1.0, 4.5) mm in the FNS group versus 0.6 (0.0, 2.6) mm in the CCS group at 1 month postoperatively (P<0.001); 3.7 (1.8, 6.4) mm in the FNS group versus 1.2 (0.6, 3.8) mm in the CCS group at 3 months (P<0.001); 4.1(2.4, 7.7) mm in the FNS group versus 2.3 (1.1, 4.4) mm in the CCS group at 6 months (P<0.001); 4.2 (2.6, 7.7) mm in the FNS group versus 2.6 (1.3, 4.6) mm in the CCS group at 12 months (P<0.001); and 4.5 (2.8, 8.0) mm in the FNS group versus 2.8 (1.5, 4.8) mm in the CCS group at 18 months (P<0.001). The two groups showed no significant differences in HHS, reoperation, and reduction quality.

CONCLUSION

Compared to CCS, FNS is deficient in preventing femoral neck shortening. Future research should focus on improving FNS in terms of preventing femoral neck shortening.

Biomechanical analysis of a new cannulated screw for unstable femoral neck fractures

Background

The treatment of unstable femoral neck fractures (FNFs) remains a challenge. In this study, a new cannulated screw for unstable FNFs was designed to provide a new approach for the clinical treatment of these injuries, and its biomechanical stability was analyzed using finite element analysis and mechanical tests.

Methods

An unstable FNF model was established. An internal fixation model with parallel inverted triangular cannulated screws (CSs) and a configuration with two superior cannulated screws and one inferior new cannulated screw (NCS) were used. The biomechanical properties of the two fixation methods were compared and analyzed by using finite element analysis and mechanical tests.

Results

The NCS model outperformed the CSs model in terms of strain and stress distribution in computer-simulated reconstruction of the inverted triangular cannulated screw fixation model for unstable FNFs. In the biomechanical test, the NCS group showed significantly smaller average femoral deformation (1.08 ± 0.15 mm vs. 1.50 ± 0.37 mm) and fracture line displacement (1.43 ± 0.30 mm vs. 2.01 ± 0.47 mm). In the NCS group, the mean stiffness was significantly higher than that in the CSs group (729.37 ± 82.20 N/mm vs. 544.83 ± 116.07 N/mm), and the mean compression distance was significantly lower than that in the CSs group (2.87 ± 0.30 mm vs. 4.04 ± 1.09 mm).

Conclusion

The NCS combined with two ordinary cannulated screws in an inverted triangle structure to fix unstable FNFs can provide better biomechanical stability than CSs and exhibit a length- and angle-stable construct to prevent significant femoral neck shortening.

In vitro biomechanical analysis of a locking self-compression screw model applied to Pauwels III and comminuted femoral neck fractures

Femoral neck fractures (FNFs) affect the young adult population and are intimately related to high-energy trauma. Despite innovations in osteosynthesis materials, the rate of complications remains at 10%-59% in Pauwels type III (PIII) fractures. The authors thus propose a fixation model with a novel self-compression screw, comparing it to a sliding hip screw plate associated with a derotation screw in the fixation of a PIII fracture with posterior inferior comminution. The finite element method (FEM) was used in this comparison along with a virtual femur model with structural characteristics similar to those of a healthy young human bone. We formed 4 groups: Group 1 (GC), intact bone; Group 2 (SHS+S), sliding hip screw plate with derotation screw; Group 3 (XS), X-pin + SS (self-compression model with superior positioning screw); Group 4 (XI), X-pin + IS (self-compression model with inferior positioning screw). A 700 N monotonic load was applied to the apex of the femur head towards the ground so that stress was mainly focused on the fracture site and osteosynthesis. Analyses included total displacement and maximum principal stress and were performed for all groups. Fracture displacement, rotation, and von Mises were assessed only in groups that underwent osteosynthesis. Total displacement values in groups with self-compression screws (XS and XI) were closer to those for healthy femurs, with a 38.5% reduction when comparing the XS group with the SHS+S group. Fracture displacement and rotation values presented reductions of over 60% when comparing the XS and XI groups with the SHS+S group. Equivalent Von Mises stress values were similar between XS and XI and presented a reduction of approximately 5.25% when compared with the SHS+S group. Our FEM analyses demonstrated that the self-compression screw model has potential biomechanical advantages over the SHS+S model.

Biomechanical performance of talon cannulated compression device in pauwels type III fractures: a comparative study

INTRODUCTION

Pauwels Type III fractures are unstable and frequently treated with cannulated screws (CS) or dynamic hip screws (DHS). The newly developed talon-cannulated compression devices (TCCD) have the potential to provide rotational stability, mainly through their talon. The study investigates whether TCCD has mechanical advantages over conventional screws or can be as stable as DHS in a reverse triangle configuration for an unstable femoral neck fracture.

MATERIAL AND METHODS

After creating a standard Pauwels Type III unstable femoral neck fracture in 36 synthetic femur bones in cortical/hard cancellous bone density, 18 were reserved for dynamic-static tests, and 18 were used for torsional tests. Each group containing 18 synthetic bones was divided into three groups to apply three different fixation materials (CS, DHS, and TCCD), with six models in each group. The displacement amounts after dynamic-static tests were measured using the AutoCAD program according to the reference measurement criteria. During the dynamic tests, a series of photographs were taken. During the static tests, the beginning and post-test photographs were taken. Finally, torsional tests were performed until implant failure occurred in the synthetic femur.

RESULTS

In static axial loading tests, TCDD was found to be statistically superior to conventional CS in AL-BL distance (p = 0,014) and CL distance (p = 0,013) measurements, and there was no significant difference between the other groups. There was no significant difference between all groups in dynamic axial compression tests in any points of interest. In torsional tests, TCCD outperformed cannulated screws in stiffness (p = 0,001) and maximum torque (p = 0,001) categories, and they provided statistically significant superiority to DHS in yield torque (p<0,001) category.

CONCLUSIONS

Biomechanically, TCCD predominates conventional cannulated screws in femoral neck fractures. TCCD also has superior torsional properties than DHS in the yield torque category. Therefore, TCCD could be the implant of choice for unstable femoral neck fractures.

Biomechanical Comparison between Inverted Triangle and Vertical Configurations of Three Kirschner Wires for Femoral Neck Fracture Fixation in Dogs: A Cadaveric Study

The purpose of this study was to compare single-cycle axial load and stiffness between inverted triangle and vertical configurations of three Kirschner wires (K-wires) for femoral neck fracture fixation in small dog cadaveric models. In each of the eight cadavers, the basilar femoral neck fracture model was prepared on both sides of the femur. One side of the femur was stabilized with three 1.0 mm K-wires of an inverted triangle configuration (group T), and the other femur was stabilized with a vertical configuration (group V). Postoperatively, the placement of the K-wires was evaluated with radiographic and computed tomography (CT) images, and static vertical compressive loading tests were performed. The mean yield load and the lateral spread were significantly higher in group T compared to group V (p = 0.023 and <0.001). On the cross-section of femoral neck at the level of the fracture line, the surface area between K-wires was significantly larger (p < 0.001) and the mean number of cortical supports was significantly higher in group T (p = 0.007). In this experimental comparison, the inverted triangle configuration of three K-wires was more resistant to failure under axial loading than the vertical configuration for canine femoral neck fracture fixation.

Evaluation of a Locking Autocompression Screw Model in Pauwels Type-3 Femoral Neck Fracture: In Vitro Analysis

Femoral neck fractures in young adults are uncommon, resulting from high-energy trauma. Despite their infrequency in this population, there is higher rate of complications, especially in the more vertical fracture line, classified by Pauwels as a type-3 femoral neck fracture. The implant type is of paramount importance for maintaining anatomical reduction, since it must resist the deforming forces that act on the fracture. We comparatively evaluated two constructions of the novel locking autocompression implant (X-PIN and X-PIN+P) using the finite element method and previously established methods for treating Pauwels type-3 femoral neck fractures. Six fixation models were developed for the study: a dynamic hip screw (DHS), a DHS with an anti-rotation screw (DHS+P), the inverted triangle multiple cannulated screws construction (ASNIS), the multiple cannulated screws in an L-configuration (L), and the two models of the novel locking autocompression screw (X-PIN and X-PIN+P). Under the same conditions with a load of 2100 N, the following parameters were evaluated using SIMLAB® software: the main maximum (Max P), main minimum (Min P), localized maximum P1 (Max P1), localized maximum P2 (Max P2), total displacement, localized displacement, rotation displacement, and von Mises stress. Compared to the DHS+P and ASNIS models, the X-PIN+P model presented, respectively, increases of 51.6% and 64.7% for Max P, 85% and 247% for Min P, and 18.9% and 166.7% for von Mises stress. Max P1 did not differ between the models, but Max P2 was 55% and 50% lower for X-PIN+P than ASNIS and L, respectively. All displacement values were lower for X-PIN+P than the other models. In this FEM testing, the X-PIN+P was superior to the other models, which was due to improvement in all parameters of stress distribution, displacement, and von Mises stress compared to models using a lateral plate (DHS and DHS+P) or not (ASNIS and L).

Multiple cannulated screw fixation of femoral neck fractures with comminution in young- and middle-aged patients

Objective

To investigate the distribution and influence of comminution in femoral neck fracture (FNF) patients after cannulated screw fixation (CSF).

Methods

From January 2019 to June 2020, a total of 473 patients aged 23–65 years with FNF treated by CSF were included in the present study. Based on location of the cortical comminution, FNF patients were assigned to two groups: the comminution group (anterior comminution, posterior comminution, superior comminution, inferior comminution, multiple comminutions) or the without comminution group. The incidence of postoperative complications, quality of life and functional outcomes was recorded at 1-year follow-up.

Results

Comminution was more likely to appear in displaced FNF patients (86.8%) compared with non-displaced FNF patients (8.9%), and the rate of comminution was closely associated with Pauwels classification (3.2% vs 53.5% vs 83.9%, P < 0.05). The incidence of osteonecrosis of the femoral head (ONFH, 11.3% vs 2.9%, P < 0.05), nonunion (7.5% vs 1.7%, P < 0.05), femoral neck shortening (21.6% vs 13.4%, P < 0.05) and internal fixation failure (11.8% vs 2.9%, P < 0.05) was significantly higher in FNF patients with comminutions, especially with multiple comminutions, than those without. Furthermore, there was a significant difference in the Harris hip score (HHS, 85.6 ± 15.6 vs 91.3 ± 10.8, P < 0.05) and EuroQol five dimensions questionnaire (EQ-5D, 0.85 ± 0.17 vs 0.91 ± 0.18, P < 0.05) between FNF patients with comminution and those without. There was no significant difference in Visual analogue scale scores (VAS, 1.46 ± 2.49 vs 1.13 ± 1.80, P > 0.05) between two groups at 1 year post-surgery.

Conclusion

Comminution is a risk factor for postoperative complications in young- and middle-aged patients with displaced and Pauwels type III FNF who undergo CSF. This can influence the recovery of hip function, thereby impacting quality of life. Further evaluation with a more comprehensive study design, larger sample and long-term follow-up is needed.

A Novel Fluoroscopic View for Improved Assessment of the Safety of the Posterosuperior Screw in Femoral Neck Fracture Fixation

BACKGROUND

The purpose of the present study was to determine specific fluoroscopic views of the femoral neck to accurately identify partially extraosseous ("in-out-in"; IOI) placement of the posterosuperior screw for fixation of femoral neck fractures.

METHODS

A 3.2-mm guide pin was placed in the posterosuperior aspect of 2 synthetic femur models: 1 entirely intraosseous and 1 IOI. Sequential fluoroscopic images were made at 5° intervals in order to identify which fluoroscopic projections identified IOI guide pin placement. These images were utilized to inform screw placement and assessment in the second phase of the study, which involved the use of cadaveric specimens. In Phase II, the posterosuperior screw of the inverted triangle was placed in 10 cadaveric specimens with use of a standard posteroanterior fluoroscopic view and 1 of 2 lateral views, either (1) neck in line with the shaft, i.e., 0° lateral; or (2) a -15° rollunder view. The final fluoroscopic views (i.e., the posteroanterior and multiple lateral and oblique views) were randomized and blinded for review by 10 orthopaedic residents and 5 attending orthopaedic traumatologists. Specimens were stripped of soft tissue and inspected for screw perforation.

RESULTS

Overall accuracy of respondents was 68.8%, with no difference between the attending traumatologists (71.8%) and resident surgeons (67.4%; p = 0.173). Interobserver reliability was moderate (κ = 0.496). Dissection identified that 4 (40%) of 10 screws were extraosseous. All of the extraosseous screws were placed with use of the 0° lateral view. The -15° rollunder lateral view was the most sensitive (81.7%) and specific (92.2%) view for identifying IOI screw placement.

CONCLUSIONS

Surgeons often utilize the standard posteroanterior and 0° lateral fluoroscopic views to safely place screws; however, many of these screws are IOI. The addition of a -15° rollunder lateral view significantly improved identification of IOI screws in the posterosuperior femoral neck. Unidentified IOI screw placement may result in damage to the blood supply of the femoral head.

Is Emergency Surgery an Indicator of Good Functional Outcomes in Neck of Femur Fractures Among Adults: A Prospective Clinical Study

Background

Because of their high frequency and severity, femoral neck fractures are a major public health concern. There is a scarcity of recorded literature that relates the timing of surgery, the effect of displacement, and the tamponade effect of the neck of the femur fracture (FNF) issues such as non-union and avascular necrosis of the femoral head after surgery. This study aimed to assess the association between the timing of the surgery and its functional outcome and surgical complications.

Methodology

This observational study was done among patients diagnosed with an FNF who were admitted in a tertiary care center for a period of three years. The study included 36 participants who were selected using the universal sampling technique. Regarding the timing of the surgery, the study participants were divided into two groups, namely, patients who were operated on before 24 hours and those who were operated on after 24 hours.

Results

The mean age of the study participants was 36.19 years, and about 75% were males. About 25% of the participants had a complication. There was a statistically significant association between functional assessment at 24 months and surgery done before 24 hours and non-displaced fracture. Moreover, there was a statistically significant association between the timing of surgery before 24 hours and fewer complications.

Conclusions

In young adults, the timing of the surgery (before 24 hours) had good functional outcomes after 24 months than the late timing of the surgery (after 24 hours). Whereas there was no statistically significant difference for functional outcomes at the one-month follow-up with the timing of the surgery. Males had a high probability of getting an FNF. The prevalence of complications was low in individuals operated on before 24 hours.

[Clinical application of new three-dimensional honeycomb guide in percutaneous cannulated screw fixation of femoral neck fracture]

OBJECTIVE

To design a new type of three-dimensional honeycomb guide for percutaneous cannulated screw placement in femoral neck fracture and evaluate its effectiveness.

METHODS

The clinical data of 40 patients with femoral neck fracture who met the selection criteria between June 2019 and December 2020 were retrospectively analyzed. According to different intraoperative positioning methods, they were divided into control group (20 cases, free hand positioning screws) and study group (20 cases, new guide assisted positioning screws). There was no significant difference in gender, age, side, cause of injury, Garden classification, and time from injury to operation between the two groups ( P>0.05). The operation time, fluoroscopy times, guide needle puncture times, and fracture healing time of the two groups were recorded. The hip function was evaluated by Harris score at last follow-up. At immediate after operation, the following imaging indexes were used to evaluate the accuracy of screw implantation distribution: screw spacing, screw coverage area, distance from screw to cervical cortex, parallelism between screws, and screw to cervical axial deviation.

RESULTS

All operations were successfully completed, and the guide needle did not penetrate the femoral neck cortex. There was no significant difference in operation time and fluoroscopy times between the two groups ( P>0.05); the guide needle puncture times in the study group was significantly less than that in the control group ( t=8.209, P=0.000). Imaging detection at immediate after operation showed that the screw spacing and screw coverage area in the study group were significantly greater than those in the control group ( P<0.05); the distance from screw to cervical cortex, parallelism between screws, and screw to cervical axial deviation were significantly smaller than those in the control group ( P<0.05). All patients were followed up 7-25 months, with an average of 19.3 months. There was no significant difference in follow-up time between the two groups ( t=-0.349, P=0.729). There were 2 cases of fracture nonunion in the control group and 1 case in the study group, and the other fractures completely healed. One case of osteonecrosis of the femoral head occurred in the control group. During the follow-up, there was no complication such as vascular and nerve injury, venous thrombosis, screw penetration, withdrawal, breakage, and refracture, etc. There was no significant difference in fracture healing time and Harris score at last follow-up between the two groups ( P>0.05).

CONCLUSION

The new three-dimensional honeycomb guide has the advantages of simple structure and convenient use. It can reduce the puncture times of the guide needle and effectively improve the accuracy distribution of cannulated screw implantation.

Mapping of Vertical Femoral Neck Fractures in Young Patients Using Advanced 2 and 3-Dimensional Computed Tomography

OBJECTIVE

To better describe the pathoanatomy of young patients' femoral neck fractures with the goal of improving surgeons' decisions for treatment including reduction and fixation.

DESIGN

This is a retrospective study of patient records, plain radiographs, and the modern computed tomography scans to study the pathoanatomy of Pauwels II and III femoral neck fractures (coronal angle >30 degrees) in young adults.

SETTING

One American College of Surgeons Level 1 trauma center.

PATIENTS

All patients 18-49 years of age with a surgically repaired Pauwels' II and III (>30 degrees) femoral neck fracture between 2013 and 2017.

METHODS

Fifty-six adult patients younger than 50 years were identified with a femoral neck fracture in the study period, of whom 30 met study criteria. We evaluated plain radiography and computed tomography data including fracture orientation, characteristics of fracture morphology including size, shape, and dimensions, comminution, displacement, and deformity.

RESULTS

Fracture morphology typically included a wide-based caudal head-neck segment (80%) that ends at a variable location along the medial calcar, sometimes as caudal as the lesser trochanter. Comminution was present in 90% of cases mostly located in the inferior quadrant, but anterior or posterior to the void left by the head-neck's caudal segment. The fractures orientations and deformities were reported by means and ranges.

CONCLUSIONS

We investigated and reported on the pathoanatomy of high-energy femoral neck fractures in young adults with the goal of increasing understanding of the injury and improving surgeons' ability to provide for improved treatment decisions and quality fracture repair.

LEVEL OF EVIDENCE

Diagnostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

[Treatment of unstable femoral neck fracture with posteromedial comminutations by cannulated screws and medial bracing plate combined with bone allograft]

Objective

To evaluate the effectiveness of unstable femoral neck fracture with posteromedial comminutations treated by cannulated screws and medial bracing plate combined with bone allograft.

Methods

The clinical data of 18 patients with unstable femoral neck fracture with posteromedial comminutations treated by cannulated screws and medial bracing plate combined with bone allograft between July 2016 and March 2020 were retrospectively analyzed. The age ranged from 22 to 64 years, with a median age of 43 years. The causes of injury included 11 cases of falling injury, 3 cases of traffic accident injury, and 4 cases of fall from height injury. According to Garden classification, the femoral neck fracture was classified as type Ⅲ in 3 cases, type Ⅳ in 15 cases, and all patients were type Ⅲ according to Pauwels classification. The time from injury to operation was 1-5 days, with an average of 2.3 days. The fracture healing time and complications were recorded. The quality of fracture reduction was evaluated by Garden index immediately after operation; at last follow-up, the degree of femoral neck shortening was determined by Zlowodzki method, Harris score was used to evaluate hip function.

Results

The operation time was 62-98 minutes (mean, 75 minutes); intraoperative blood loss was 101-220 mL (mean, 153 mL). Cannulated screws guide wire was inserted 3-5 times (mean, 4 times). Intraoperative fluoroscopy was performed 9-21 times (mean, 15 times). The hospital stay was 5-11 days (mean, 7.2 days). All the patients were followed up 12-40 months with an average of 17.3 months. There was no postoperative complication such as accumulated pneumonia, lower extremity deep venous thrombosis, nail cutting, nail withdrawal, internal fixation fracture, and so on. There was no fracture nonunion and osteonecrosis of the femoral head during the follow-up; the fracture healing time was 7-15 weeks, with an average of 12.1 weeks. The quality of fracture reduction was evaluated immediately after operation, the results were grade Ⅰ in 15 cases and grade Ⅱ in 3 cases. At last follow-up, there were 2 cases with femoral neck shortening less than 5 mm and 1 case with 5-10 mm. The incidence of femoral neck shortening was 16.7%. The Harris score of hip joint was 73-97, with an average of 93.5; among them, 12 cases were rated as excellent, 3 cases as good, and 3 cases as fair, with an excellent and good rate of 83.3%.

Conclusion

For the treatment of unstable femoral neck fracture with posteromedial comminutations, cannulated screws and medial bracing plate combined with bone allograft are dramatically effective due to earlier weight bearing, faster fracture healing, and better hip function recovery.

Configuration of short- and long-threaded cannulated screws in proximal femoral plating decreases varus collapse of femoral neck fractures: A retrospective cohort study

OBJECTIVES

Proximal femoral plating serves as a good alternative for the fixation of femoral neck fractures, but fixation loss still occurs. This study aimed to evaluate the effect of a hybrid configuration of short- and long-threaded cannulated screws in proximal femoral plating in terms of decreasing varus collapse of femoral neck fractures.

MATERIALS AND METHODS

We retrospectively analyzed 86 patients with femoral neck fractures who were fixed by proximal femoral plating from January 2015 to June 2019. These patients were divided into two groups according to screw configuration: short- and long-threaded cannulated screws (SLTS, n = 38) and short-threaded cannulated screws (STS, n = 48). Radiological and clinical outcomes including screw withdraw, nonunion, avascular necrosis, caput-collum-diaphysis (CCD) angle, amount of femoral neck shortening (FNS), and Harris Hip Score (HHS) were compared between the groups.

RESULTS

Preoperative characteristics including age, gender, Garden type, duration of surgery, and reduction quality were not significantly different between the two groups (p > 0.05). Less decreased CCD angle was observed in the SLTS group (-0.4° (-1.4 - 1.8)) compared with that in the STS group (7.9° (6.3 - 11.0)) (p < 0.001). The SLTS group also presented with fewer amount of FNS (3.2 (2.7 - 3.8) mm vs. 5.1 (4.2 - 5.9) mm, p < 0.001). Bone union was achieved in all patients and no avascular necrosis was observed during the follow-up. The HHS was higher in the SLTS group (86.4 ± 5.1) than that in the STS group (81.5 ± 4.5) (p < 0.001).

CONCLUSION

The hybrid configuration of short- and long-threaded screws in proximal femoral plating offers better resistance against varus collapse and yields better functional outcomes in femoral neck fractures.

Analysis on risk factors for neck shortening after internal fixation for Pauwels II femoral neck fracture in young patients

Background

Femoral neck shortening can occur in young patients receiving internal fixation for Pauwels type II femoral neck fracture. The risk factors for neck shortening, which can affect hip function, are not clear. This study aimed to retrospectively identify risk factors for neck shortening after internal fixation with parallel partially threaded cannulated cancellous screws (FPTCS) for Pauwels type II femoral neck fracture in relatively young patients.

Methods

Clinical data from 122 cases with Pauwels type II femoral neck fracture from February 2014 to February 2019 were reviewed and analyzed, and causes of neck shortening were statistically analyzed. And the Chi-squared test or Fisher’s exact test was used to compare indicators. Multivariate analysis was conducted with non-conditional logistic regression analysis.

Results

Statistically significant differences were found in age, sex, BMD, BMI, fracture type, posterior medial cortex comminution, and reduction quality between patients with femoral neck shortening and those without femoral neck shortening. Logistic regression analysis showed that fracture type, posterior medial cortex comminution, and reduction quality were the main risk factors for neck shortening.

Conclusion

Fracture type, posterior medial cortex comminution, and reduction quality can be used as important reference indexes to predict the possibility of neck shortening after internal fixation with FPTCS for Pauwels type II femoral neck fracture in young patients. BMD and BMI may be also risk factors.

Proposal for a New Fixation Method for Pauwels Type III Femoral Neck Fracture-Metaphyseal Stem: A Finite-Element Analysis

OBJECTIVE

To evaluate the biomechanical behavior of a metaphyseal stem specifically designed for the fixation of Pauwels type-III femoral neck fractures using finite-element analysis.

METHODS

Three different constructions were studied: the dynamic hip screw with a superior anti-rotation screw (DHS + ARS), multiple cannulated screws in an inverted triangle configuration (ASNIS), and the Metaphyseal Nailing System (MNS), a new implant developed by the authors. Vertical and total displacement, localized and total maximum and minimum principal, and the Von Mises peak stresses were evaluated.

RESULTS

Results are shown for the DHS + ARS, ASNIS, and MNS models, respectively. Vertical displacement (mm) was 1.49, 3.63, and 1.90; total displacement (mm) was: 5.33, 6.02, and 6.30; localized maximum principal (Mpa) was: 2.77, 4.5, and 1.7; Total maximum principal (Mpa) was: 126, 223, and 531; localized minimum principal (Mpa) was: -1.8, -3.15, and -0.39; total minimum (Mpa) was: -121, -449, and -245; and Von Mises peak stress (MPA) was: 315.5, 326.1, and 286.0.

CONCLUSION

The present FEM study showed that the MNS device increases general stresses and reduces localized stresses, when compared to the DHS + ARS and ASNIS constructions used to fix Pauwels type-III femoral neck fracture in synthetic models. In this sense, the MNS showed a low fracture focus shift, conducive to the consolidation environment. The significant reduction in the maximum principal stress, allows to affirm that the main deforming force, the shear, in this fracture pattern, was considerably reduced and the low value of Von Mises obtained, consistent with an implant capable of making an effective load sharing.

Finite Element Analysis of Femoral Neck Fracture Treated with Bidirectional Compression-Limited Sliding Screw

Background

The rate of femoral neck shortening after internal fixation for femoral neck fracture is high and this complication reduces the function of the affected lower limb. The aim of this study was to design a bidirectional compression-limited sliding screw (BCLSC) that can achieve a full balance between retaining the sliding pressure of the ends of and maintaining the length of the femoral neck.

Material/Methods

We constructed a 3-dimensional model of a Pauwels III femoral neck fracture and models of 3 internal fixation methods (3 cannulated screws [3CS], dynamic hip screw [DHS]+CS, and BCLSC) by finite element analysis (FEA).The finite element model simulated the loading of the human body when standing on 1 leg. Displacement and stress distribution of the models were calculated based on an axial stress of 600 N.

Results

The peak von Mises stress (VMS) values of fracture ends in the 3CS, DHS+CS and BCLSC groups were 94.687 MPa, 26.375 MPa and 45.698 MPa; the peak VMS values of internal fixed stress were 451.53 MPa, 174.45 MPa, and 337.34 MPa; the peak VMS values of the lateral femoral wall were 70.021 MPa, 53.033 MPa, and 20.009 MPa; maximum displacements of the femoral head were 1.4482 mm, 1.3813 mm, and 1.3889 mm; and the internal fixed displacement peaks were 4.1134 mm, 3.91 mm, and 4.1004 mm, respectively.

Conclusions

The FEA showed that compared with the CS, the new BCLSC showed better performance in resisting shearing force for Pauwels III femoral neck fracture, with better mechanical properties. These data provide a basis for further experiments and clinical application.

Radiographic Quantification of Safe Zones for Screw Placement in the Femoral Neck: A Computed Tomography-Based Analysis

OBJECTIVES

The purpose of this study is to design a radiographic map of the femoral neck showing proportion-based locations of the safe zones for screw placement with widest bony extents in anteroposterior and lateral radiographs using normal computed tomography-based data.

METHODS

We analyzed computed tomography-based studies of 50 intact normal proximal femora equally from male and female subjects. Using software-developed radiographs, the proportionate locations of the maximal anteroposterior and cephalocaudal extents in both constricted zones were measured. The width of the femoral neck in the measurement zone was taken as the reference for calculation of proportions.

RESULTS

For anteroposterior radiographs, the anteroposterior safe zones in the femoral neck are located at the gradients of 34.21% and 34.33% from the superior border in midcervical and basicervical regions, respectively. In lateral radiographs, they correlate with the visible anterior extent of femoral neck and lie at a gradient of 7.16% and 11.79% from the visible posterior border in midcervical and basicervical regions, respectively. In lateral radiographs, the calcar-based cephalocaudal safe zone was located at the gradients of 43.49% and 39.53% from the visible posterior border in midcervical and basicervical regions, respectively. In anteroposterior radiographs, cephalic limit of the calcar-based safe zone is located at the gradients of 9.63% and 17.82% from the superior border in midcervical and basicervical regions, respectively.

CONCLUSIONS

Radiographic margins cannot be reliably trusted for screw fixation of femoral neck fractures. The proportionate locations of the anteroposterior and calcar-based cephalocaudal safe zones with widest bone stock in anteroposterior and lateral fluoroscopic projections can help in the safe placement of screws for fixation of femoral neck fractures.

Biomechanical study of different internal fixations in Pauwels type III femoral neck fracture - A finite elements analysis

OBJECTIVE

To evaluate biomechanical behavior of different internal fixation methods for the treatment of Pauwels Type III femoral neck fractures.

METHODS

Three internal fixators were developed to treat Pauwels Type III femoral neck fracture using finite elements: dynamic hip screw (DHS); DHS combined with anti-rotation screw; three cannulated screws in an inverted triangular configuration (ASNIS). Under the same conditions, vertical fracture displacement, and maximum and minimum principal, and Von Mises stresses were evaluated.

RESULTS

The vertical displacements evaluated were: 5.43 mm, 5.33 mm and 6.22 mm, rotational displacements values were 1.1 mm, 0.4 mm and 1.3 mm; maximum principle stress values obtained for the upper region of the femoral neck were 3.26 hPa, 2.77 hPa, and 4.5 hPa, minimum principal stress values obtained for the inferior region of the femoral neck were -1.97 hPa, -1.8 hPa and t -3.15 hPa; Von Mises peak stress values were 340.0 MPa, 315.5 MPa and 326.1 Mpa, for DHS, DHS with anti-rotation device, and ASNIS, respectively. Conclusion: The DHS combined with anti-rotation screw yielded better results in terms of rotational and vertical displacements, traction and compression distributions on fractures, and Von Mises stress, demonstrating mechanical superiority for Pauwels Type III fracture.

Risk factors associated with osteonecrosis of femoral head after internal fixation of femoral neck fracture:a systematic review and meta-analysis

BACKGROUND

Although the risk factors associated with osteonecrosis of femoral head (ONFH) after internal fixation of femoral neck fracture (IFFNF) have been frequently reported, the results remain controversial. Therefore, its related risk factors were systematically evaluated and meta-classified in this study.

METHODS

Literature on risk factors of ONFH caused by IFFNF was retrieved in PubMed, Embase and Cochrane Library due June 2019. Review Manager 5.3 software was applied to data synthesis, and Stata 13.0 software was adopted for analyses of publication bias and sensitivity.

RESULTS

A total of 17 case-control studies with 2065 patients were included. The risk of ONFH after IF was 0.40-fold higher in patients with Garden III-IV FNF than that in patients with Garden I-II (OR: 0.40, 95%CI: 0.29-0.55). The risk of OFNH with retained IF was uplifted by 0.04 times (OR: 0.04, 95%CI: 0.02-0.07). There was nonsignificant relationship between gender and ONFH after IFFNF (OR: 1.27, 95%CI: 0.84-1.94). Moreover, ONFH after IFFNF presented no association with age (OR:1.66, 95%CI: 0.89-3.11), injury-operation interval (OR:1.29, 95%CI: 0.82-2.04), fracture reduction mode (OR:1.98, 95%CI: 0.92-4.26), preoperative traction (OR:1.69, 95%CI: 0.29-9.98) and mechanism of injury (OR:0.53, 95%CI: 0.06-4.83). Egger's and Begg's tests indicated a publication bias (P = 0.001).

CONCLUSION

It was demonstrated that Garden classification and retained IF were important influencing factors of ONFH after IFFNF. Gender, age, injury-operation interval, fracture reduction mode, preoperative traction and the mechanism of ONFH were irrelevant to the complication.

Biomechanics of Osteoporotic Fracture Fixation

PURPOSE OF REVIEW

Fractures of osteoporotic bone in elderly individuals need special attention. This manuscript reviews the current strategies to provide sufficient fracture fixation stability with a particular focus on fractures that frequently occur in elderly individuals with osteoporosis and require full load-bearing capacity, i.e., pelvis, hip, ankle, and peri-implant fractures.

RECENT FINDINGS

Elderly individuals benefit immensely from immediate mobilization after fracture and thus require stable fracture fixation that allows immediate post-operative weight-bearing. However, osteoporotic bone has decreased holding capacity for metallic implants and is thus associated with a considerable fracture fixation failure rate both short term and long term. Modern implant technologies with dedicated modifications provide sufficient mechanical stability to allow immediate weight-bearing for elderly individuals. Depending on fracture location and fracture severity, various options are available to reinforce or augment standard fracture fixation systems. Correct application of the basic principles of fracture fixation and the use of modern implant technologies enables mechanically stable fracture fixation that allows early weight-bearing and results in timely fracture healing even in patients with osteoporosis.

Medial anatomical buttress plate in treating displaced femoral neck fracture a finite element analysis

BACKGROUND

Displaced femoral neck fractures in young adults are most likely to result from high energy trauma that causes a vertically-oriented shearing injury through the femoral neck. The optimal strategy for treatment of displaced femoral neck fractures remains an unsolved challenge in orthopedic surgery.

METHODS

our group has previously designed a medial anatomical buttress plate (MABP) based on the analysis of the computed tomography (CT) data of anatomical structures derived from a large sample population. In this study, finite element analyses (FEA) were carried out to compare the outcomes of the combination of our MABP with cannulated screws to those of the combination of tubular plate with cannulated screws, and to those of using cannulated screws alone.

RESULTS

MABP resulted in a more stable fixation as compared to the other two approaches, with respect to the femur and the stress distributions, stress peaks, and Z axis displacements.

CONCLUSIONS

The FEA encouraged us that addition of a medial buttress plate not only achieved superior medial buttress stability but also achieves superior performance because it perfectly fits with the existing anatomic structure of medial femoral neck. The results from our study may provide references for clinical decision making in dealing with such patients.

Minimally invasive open reduction combined with proximal femoral hollow locking plate in the treatment of Pauwels type III femoral neck fracture

Objective

This study was performed to investigate the clinical effects of minimally invasive open reduction and internal fixation with a proximal femoral hollow locking plate on Pauwels type III femoral neck fractures.

Methods

The clinical data of 45 patients aged 32.0 ± 8.1 years (range, 19–45 years) with Pauwels type III femoral neck fractures treated from March 2012 to August 2016 were retrospectively analyzed. All patients underwent anterolateral minimally invasive open reduction and proximal femoral hollow locking plate fixation of the hip joint. Garden’s index was used to evaluate the quality of fracture reduction. Complications and fracture healing were recorded in all patients. At the last follow-up, the functional outcome was recorded using the Harris hip score.

Results

No complications such as femoral neck shortening, internal fixation loosening, or refracture occurred. However, three patients required reoperation (one with nonunion and two with femoral head necrosis). At the last follow-up, the mean Harris hip score was 92.1 ± 4.5 (range, 76–98). The rate of excellent and good Harris hip scores was 93.3%.

Conclusion

The herein-described strategy for Pauwels type III femoral neck fractures is advantageous in terms of high reduction quality, firm fixation, and prevention of neck shortening.

BIOMECHANICAL ANALYSIS OF DIFFERENT SURGICAL STRATEGIES FOR THE TREATMENT OF ROTATIONALLY UNSTABLE PELVIC FRACTURE USING FINITE ELEMENT METHOD

A rotationally unstable pelvic fracture can lead to loss of function and limit moving ability. Immediate fracture fixation is needed for patients with the pelvic fractures. However, it may be difficult to evaluate different surgical strategies for the fracture treatments due to variations in patients’ anatomies and surgical techniques. Thus, the purpose of the present study was to analyze the biomechanical performances of the intact, injured, and treated pelvises based on different physiological movements of the spine using finite element method. Three-dimensional musculoskeletal finite element models of the spine-pelvis-femur complex were developed. The intact pelvis, the rotationally unstable pelvis, and six types of pelvic fixation techniques were analyzed. Additionally, seven types of physiological movements of the spine were also considered. The results showed that the posterior iliosacral screws combined with lower and anterior plate (PIS-LAP) had good fixation stability, lower plate stress, and lower pelvic stress. However, the PIS-LAP increased the stress of the posterior iliosacral screws. The right lateral bending, left lateral bending, and flexion significantly affect all the biomechanical performances compared to the other physiological movements of the spine. The present study can provide engineers and surgeons with the understanding of the biomechanics of various fixation techniques during different physiological movements for the treatment of rotationally unstable pelvic fractures.

Finite element analysis of different internal fixation methods for the treatment of Pauwels type III femoral neck fracture

OBJECTIVE

To compare the bifomechanical advantages and disadvantages of different internal fixation methods for the treatment of Pauwels type III femoral neck fractures.

METHODS

4 internal fixations were developed to treat Pauwels type III femoral neck fracture finite element models: a: the "F" shaped cannulated screw model, b: the traditional cannulated screw model, c: the "F" shaped cannulated screw coupled with medial plate model, d: the traditional cannulated screw coupled with medial plate. Under the same conditions, the 4 internal fixations and femur of von Mises stress and displacement distribution were studied.

RESULTS

The most significant displacement of all models occurred at the femoral head. The maximum displacement of the femoral heads included: a: 1.53 mm, b: 1.73 mm, c: 1.18 mm and d: 1.34 mm. The von Mises peak stresses of the femoral calcar area in different models were: a: 115.2 MPa, b: 143.5 MPa, c: 107.8 MPa and d: 120.5 MPa. The peak stresses of the four internal fixation models included: a: 318.0 MPa, b: 360.9 MPa, c: 468.8 MPa and d: 771.5 MPa.

CONCLUSION

The "F" shaped cannulated screw technique is capable of eliminating the torsional stress and shear stress while maintaining the axial compressive stress at the fracture end. Besides, the medial support plate can effectively resist the shearing force of the Pauwels III femoral neck fracture and create an excellent mechanical environment for fracture healing. Thus, for the Pauwels III femoral neck fracture, the use of "F" shaped cannulated screws combined with medial plate internal fixation are recommended.

Ideal length of thread forms for screws used in screw fixation of nondisplaced femoral neck fractures

BACKGROUND

It is common practice when placing cannulated screws within the femoral head when treating femoral neck fractures to avoid the thread-forms from crossing the fracture line. Despite the widespread use of cannulated screws in internal fixation of femoral neck fractures, there is no study to our knowledge that describes the ideal length of thread-forms.

PURPOSE

The purpose of this study is to determine the thread length that will maximize purchase within the femoral head while minimizing risk of crossing the fracture line. Additional analysis was conducted to identify factors associated with the maximal possible length of treads in minimally and non-displaced femoral neck fractures.

METHODS

We performed a retrospective study of all patients treated for a minimally or non-displaced femoral neck fracture from April 1, 2004 through December 31, 2017. Only patients who had received a pre-operative CT or MRI scan were included. Fixation was then templated using radiographs and the distance from the subchondral bone to the fracture line was then measured.

RESULTS

The study included 127 patients. The average estimated length of lag screw threads was 33.2 ± 6.67 mm, with lower quartile of 29.1 mm and higher quartile of 37.2 mm. The median was 32.0 mm and most frequently encountered estimate was 29 mm. Estimated lag screw size did not differ significantly based on age or BMI, but both height (p < 0.001) and race (0.04) were positively correlated with estimated lag screw size and males had longer measurements compared to females, 37.2 ± 7.0 mm vs 31.4 ± 5.7 mm (p < 0.001), respectively.

CONCLUSION

In conclusion, we propose an additional lag screw thread form with length 26.0 mm to capture 90% of femoral neck fractures.

Biomechanical Evaluation of Internal Fixation of Pauwels Type III Femoral Neck Fractures: A Systematic Review of Various Fixation Methods

Background

The purpose of this systematic review was to investigate various fixation methods or implants used in the treatment of Pauwels type III femoral neck fractures.

Methods

PubMed Central, OVID Medline, Cochrane Collaboration Library, Web of Science, Embase, and AHRQ databases were searched to identify relevant studies published until August 2017 with English language restriction. Studies were selected on the basis of the following inclusion criteria: biomechanical study of Pauwels type III femoral neck fractures and the use of dynamic hip screw (DHS) or multiple screw fixation or other devices for fixation of the fracture.

Results

A total of 15 studies were included in the systematic review. Eight studies were conducted using cadavers, six studies using sawbones, and one using a finite element model. During the mechanical testing, each study measured mechanical stiffness, failure to cyclic loading, failure to vertical loading of each fixation device. DHS was included in 11 studies, multiple screw fixation in 10 studies, and other devices in six studies. Baitner et al. and Samsami et al. reported that the mechanical stiffness of DHS was superior to three inverted triangular screw fixation. Hawks et al. and Gumustas et al. reported that using a transverse calcar screw can withstand vertical loading better than three inverted triangular screw fixation. In addition, there were some studies where instruments such as Intertan nail, locking plate or other devices showed excellent biomechanical properties.

Conclusions

There are a variety of methods and instruments for fixation of the Pauwels type III fractures. However, it is difficult to conclude that any method is more desirable because there are advantages and disadvantages to each method. Therefore, we should pay attention to the implant choice and consider adequate weight bearing affecting the stiffness of the implant.

Perforated H-beam implant can be used in femoral neck fracture

This biomechanical study evaluated comparison osteosynthesis of the femoral neck fracture model by 3 cannulated screw implants and new perforated H beam implants under different loading conditions with 45 third generation right proximal femur bones. A standardized Pauwels Type 3 of the femoral neck fracture was performed in the femur models. For assessing the rigidity and strength of fixation methods, the proximal femur bones after their osteosynthesis were then mechanically tested in axial compression, and torsional and dynamic axial compression loading. To determine the structural advantage of the new implant system, perforated and nonperforated new implant systems were comparing about pull out performance. When loading the samples, photographs were taken continuously. The reference parameters were described and measured from unloaded and loaded photographs of the static and dynamic tests. There was no significant difference between stiffness values of two fixation methods under static and rotational loading. Under dynamic loading, the displacement of the superior point of femoral head at the fracture line showed a significant decrease between the new implant system and cannulated screws. Comparing the relative motion at the mid line of the fracture in femoral neck between groups, a significant increase was found in H Beam implant group. Perforated H beam implants have similar static and torsion properties with golden standard. Although there was significant difference under dynamic loading which simulate movement early after surgery, the patient was not allowed to move early after surgery in the clinical practice. Therefore, the differences due to the perforated "H" beam implant would not cause clinical insecurity. Therefore, it is assumed that the perforated "H" beam implant can be used for internal fixation as an alternative to cannulated screws in the treatment of instable femoral neck fracture.

Obtuse triangle screw configuration for optimal internal fixation of femoral neck fracture: an anatomical analysis

OBJECTIVES:

To identify the optimal screw configuration for internal fixation of femoral neck fractures based on anatomic analysis on radiologic imaging.

METHODS:

30 proximal femurs of 15 adults were constructed by CT. 3 femoral neck sections (FNS), the subcapital, medial, and the fundus, were projected on to the lateral femoral trochanteric wall. The simulated 3 screw configurations in the projection of FNS include: 2 inverted equilateral triangles symmetrised to the axis of the FNS (IET-FNS group) or the coronal axis of the proximal femur (IET-PR group) and an obtuse triangle (OT group). The distance between the screws, the distance between the centre of the FNS and the screws, and the area ratio of the triangle/FNS were calculated.

RESULTS:

The projection of the FNS on to the lateral femoral trochanteric wall is displayed as a rotating forward ellipse. Measurements of distance between screws, distance between the centre of the FNS to the screws, and the area ratio of triangle/FNS were significantly larger in the OT group than in the IET-FNS and IET-PF groups ( p < 0.05). The values of the 3 parameters in the IET-FNS group were also larger than those in the IET-PF group ( p < 0.05).

CONCLUSIONS:

The obtuse triangle screw configuration displayed advantages with respect to the parameters of distance between screws, distance between the centre of FNS to screws, and the triangle area. Therefore, the obtuse triangle screw configuration may be the ideal pattern for internal fixation of femoral neck fractures (Pauwels I and II). This needs to be corroborated with biomechanics testing.

Does the Watson-Jones or Modified Smith-Petersen Approach Provide Superior Exposure for Femoral Neck Fracture Fixation?

BACKGROUND

A well-reduced femoral neck fracture is more likely to heal than a poorly reduced one, and increasing the quality of the surgical exposure makes it easier to achieve anatomic fracture reduction. Two open approaches are in common use for femoral neck fractures, the modified Smith-Petersen and Watson-Jones; however, to our knowledge, the quality of exposure of the femoral neck exposure provided by each approach has not been investigated.

QUESTIONS/PURPOSES

(1) What is the respective area of exposed femoral neck afforded by the Watson-Jones and modified Smith-Petersen approaches? (2) Is there a difference in the ability to visualize and/or palpate important anatomic landmarks provided by the Watson-Jones and modified Smith-Petersen approaches?

METHODS

Ten fresh-frozen human pelvi underwent both modified Smith-Petersen (utilizing the caudal extent of the standard Smith-Petersen interval distal to the anterosuperior iliac spine and parallel to the palpable interval between the tensor fascia lata and the sartorius) and Watson-Jones approaches. Dissections were performed by three fellowship-trained orthopaedic traumatologists with extensive experience in both approaches. Exposure (in cm) was quantified with calibrated digital photographs and specialized software. Modified Smith-Petersen approaches were analyzed before and after rectus femoris tenotomy. The ability to visualize and palpate seven clinically relevant anatomic structures (the labrum, femoral head, subcapital femoral neck, basicervical femoral neck, greater trochanter, lesser trochanter, and medial femoral neck) was also recorded. The quantified area of the exposed proximal femur was utilized to compare which approach afforded the largest field of view of the femoral neck and articular surface for assessment of femoral neck fracture and associated femoral head injury. The ability to visualize and palpate surrounding structures was assessed so that we could better understand which approach afforded the ability to assess structures that are relevant to femoral neck fracture reduction and fixation.

RESULTS

After controlling for age, body mass index, height, and sex, we found the modified Smith-Petersen approach provided a mean of 2.36 cm (95% confidence interval [CI], 0.45-4.28 cm; p = 0.015) additional exposure without rectus femoris tenotomy (p = 0.015) and 3.33 cm (95% CI, 1.42-5.24 cm; p = 0.001) additional exposure with a tenotomy compared with the Watson-Jones approach. The labrum, femoral head, subcapital femoral neck, basicervical femoral neck, and greater trochanter were reliably visible and palpable in both approaches. The lesser trochanter was palpable in all of the modified Smith-Petersen and none of the Watson-Jones approaches (p < 0.001). All modified Smith-Petersen approaches (10 of 10) provided visualization and palpation of the medial femoral neck, whereas visualization of the medial femoral neck was only possible in one of 10 Watson-Jones approaches (p < 0.001) and palpation was possible in eight of 10 Watson-Jones versus all 10 modified Smith-Petersen approaches (p = 0.470).

CONCLUSIONS

In the hands of surgeons experienced with both surgical approaches to the femoral neck, the modified Smith-Petersen approach, with or without rectus femoris tenotomy, provides superior exposure of the femoral neck and articular surface as well as visualization and palpation of clinically relevant proximal femoral anatomic landmarks compared with the Watson-Jones approach.

CLINICAL RELEVANCE

Open reduction and internal fixation of a femoral neck fracture is typically performed in a young patient (< 60 years old) with the objective of obtaining anatomic reduction that would not be possible by closed manipulation, thus enhancing healing potential. In the hands of surgeons experienced in both approaches, the modified Smith-Petersen approach offers improved direct access for reduction and fixation. Higher quality reductions and fixation are expected to translate to improved healing potential and outcomes. Although our experimental results are promising, further clinical studies are needed to verify if this larger exposure area imparts increased quality of reduction, healing, and improved outcomes compared with other approaches. The learning curve for the exposure is unclear, but the approach has broad applications and is frequently used in other subspecialties such as for direct anterior THA and pediatric septic hip drainage. Surgeons treating femoral neck fractures with open reduction and fixation should familiarize themselves with the modified Smith-Petersen approach.

Femur neck fracture in young adults, is it really an urgent surgery indication: retrospective clinical study

Introduction

Femur neck fracture comprises a significant part of intracapsular femur fracture in the intracapsular area of proximal femur and it is mostly seen in elder people. However, these kinds of fractures may be seen in young adults. The present study aims to search factors that affect femoral neck fractures in young adults after surgery carried out by internal determination method.

Methods

Files of patients who were applied internal determination through closed reduction and cannulated screw because of intracapsular femur neck fractures between 2010 and 2015 were analyzed retrospectively. Fractures were evaluated by means of Garden classification, which is based on radiological appearance. The cases were examined in terms of timing of surgery in two groups. Cases operated in the first 24 hours after trauma consisted of group 1 and after 24 hours group 2. Radiological staging in femoral head avascular necrosis was evaluated by Ficat-Arlet classification system whereas acetabular fractures and hip functionality was evaluated by Letournel and Judet system, which is based on direct graph of fracture line.

Results

Mean age at the time of surgery for 31 cases included in the study was 40.04 ± 9.63 year. The average duration from injury to surgery was 6.6 (1-20) days. Thirty nine percent of fractures was nondisplaced whereas 61% was displaced. The average follow-up period was 4.9 ± 1.35 years. The rate of nonunion was found 16% and femoral head avascular necrosis 6.4%. According to Judet System, 67.7% of cases showed excellent/good and 32.3% moderate/bad functional results. Six cases had a secondary surgery. Cases who had displaced fractures statistically showed worse functional results and underwent more secondary surgery than patients with nondisplaced fractures (P>0.05). As a result of logistic regression analysis, presence of displacement was a factor negatively affecting the judet score but did not affect the rate of complication. There were no significant differences between the two groups according to the surgical timing in terms of functional outcomes and complications.

Conclusion

Because of surgical treatment of femoral neck fractures in the first 24 hours does not affect functional outcomes and complication rate, surgery is recommended in optimal conditions. In the case of displacement, care must be taken in terms of poor functional results.

Stability of L-shaped and inverted triangle fixation assemblies in treating Pauwels type II femoral neck fracture: a comparative mechanical study

PURPOSE

The aim of our study is to compare the mechanical resistance of two screw configurations in fixating type II Pauwels femoral neck fractures.

METHODS

Fifteen synthetic models of femur bones in young adults were divided into three equal groups: intact (G1), models with fixation of a 5.0-mm failure zone created in the posterior cortex of the femoral neck using an L-shaped screw arrangement (G2, n = 5), and models with an identical failure zone fixated using an inverted triangle assembly (G3, n = 5). Model strength (axial loading) and rotational deviation of the fragments were load-tested until a 5.0-mm displacement was reached (step 1) and then until failure, here considered as 10.0 mm displacement in G2 and G3 or femoral neck fracture in G1 (step 2).

RESULTS

In step 1, the mean resistance in G1 was 1593 N (standard deviation [SD] of 62 N); this value in G2 was 1261 N (SD 49 N) and in G3 was 1074 N (SD 153 N). During step 2, the value for G1 was 2247 N (SD 84 N), for G2 was 1895 N (SD 69 N), and for G3 was 1523 N (SD 280 N). G3 (the inverted triangle assembly) showed a significantly lower maximum load than the group using the L-shaped assembly (G2) and the control group (G1), which was significant using Kruskal-Wallis analysis of variance (p = 0.002).

CONCLUSION

Under test conditions in synthetic bone, fixation using a L-shaped screw assembly provides greater mechanical resistance than an inverted triangle assembly.

Introduction of a guide based on a femoral neck section for fixation with multiple screws: a cadaveric study

BACKGROUND

The design and application of assisted instrumentation for internal fixation of femoral neck fractures with multiple screws are still evolving. A novel guide based on a femoral neck section was designed to improve the accuracy of screw placement, and its efficacy was evaluated.

METHODS

A guide based on a femoral neck section was designed for assisted fixation of femoral neck fractures with multiple screws. Femoral specimens from 10 adults (20 femurs) underwent assisted internal fixation for a femoral neck fracture with 3 cannulated screws using the new guide technique or conventional technique. The accuracy of screw orientation and entry point, the accuracy of optimal screw positioning, and drilling attempts, operative time, and fluoroscopy time were recorded.

RESULTS

Among all 20 specimens, 60 screws were inserted successfully. Screw parallelism, operative time, and fluoroscopy time showed no statistical difference between the new guide technique and conventional technique (P > 0.05). The accuracy of optimal screw positioning was determined by the contained screw area ratio, distance between screws, distance from the centre of the femoral neck section, distance between screws and the femoral neck cortex, and Drilling attempts were statistical significantly better (data in the first three were larger and in the latter two was smaller) with the new guide technique, than with conventional technique (P < 0.05).

CONCLUSIONS

This new, two-dimensional, fluoroscopy-assisted, percutaneous guide technique enables accurate and optimal screw positioning in internal fixation of femoral neck fractures, compared with conventional technique.

Percutaneous osteosynthesis and cementoplasty for stabilization of malignant pathologic fractures of the proximal femur

PURPOSE

To retrospectively evaluate the outcome of patients who underwent radiological percutaneous osteosynthesis and cementoplasty (RPOC) for stabilization of malignant pathological fracture of the proximal femur.

MATERIALS AND METHODS

The clinical files of 12 patients who underwent RPOC for stabilization of malignant pathological fracture of the proximal femur were reviewed. There were 9 men and 3 women with a mean age of 56 years±13 (SD) (range: 35-82 years). All patients had metastases of proximal femur and a high fracture risk (Mirels score≥8) and were not eligible for surgical stabilization. The primary endpoint was the occurrence of a fracture after RPOC. Secondary endpoints were the procedure time, early complications of RPOC, pain reduction as assessed using a visual analog scale (VAS) and duration of hospital stay.

RESULTS

No patients treated with RPOC had a fracture during a mean follow-up time of 382 days±274 (SD) (range: 11-815 days). RPOC was performed under general (n=10) or locoregional (n=2) anesthesia. The average duration of the procedure was 95min±17 (SD) (range: 73-121min). The technical success rate was 100%. All patients were able to walk on the day following RPOC. The average duration of hospital stay was 4days ±3 (SD) (range: 2-10 days). No major complication occurred. One patient complained of hypoesthesia in the lateral thigh. For symptomatic patients (n=7), VAS score decreased from 6.8±1.2 (SD) (range: 5-9) before treatment, to 2.3±1.1 (SD) (range: 1-4) one month later.

CONCLUSION

Preventive RPOC for pathological fracture of the proximal femur is a reliable alternative for cancer patients who are not candidates for surgical stabilization. Studies involving more patients are needed to confirm our preliminary experience.

Femoral neck collapse after internal fixation of an intracapsular hip fracture: Does it indicate a poor outcome?

The degree of femoral neck collapse that occurred after 519 patients with an intracapsular hip fracture treated by internal fixation with a Targon FN implant was measured. Mean femoral neck collapse was 8.0mm and this was increased for displaced fractures in comparison to undisplaced fractures (9.5mm versus 5.9mm, p<0.0001) and for those patients that subsequently developed fracture healing complications (11.6mm versus 7.1mm, p<0.0001). At one year from injury femoral neck collapse in excess of 15mm was associated with an increase in the degree of residual pain (p=0.01). A clear relationship between increased collapse and increased loss of mobility was demonstrated (P<0.0001). This study confirms previous smaller studies that excessive femoral neck collapse (of more than 15mm) is more common for displaced fractures and presents new data to demonstrate that excessive femoral neck collapse is associated with an increased risk of fracture healing complications and increased loss of function. Future studies are now justified that consider methods to reduce fracture collapse.

Augmentation by cerclage wire improves fixation of vertical shear femoral neck fractures-A biomechanical analysis

BACKGROUND

Femoral neck fractures in young individuals are typically vertical shear fractures. These injuries are difficult to stabilize due to a significant varus displacement force across the hip with weight bearing. The purpose of this study was to evaluate the biomechanical stability offered by the addition of an augmented wire to conventional inverted triangle triple screw fixation for stabilizing vertical shear femoral neck fracture.

METHODS

Sixteen medium 4th-generation synthetic composite femurs (Sawbones Pacific Research Laboratories, Vashon, WA) were divided into two groups. Vertical osteotomy was performed to mimic Pauwels III femoral neck fracture. Group A (n=8) was fixed with three parallel 6.5-mm cannulated screws (Stryker) with washer in inverted triangle configuration. In group B (n=8), all the screws were set using methods identical to group A, with the addition of the cerclage wire. Both groups were tested with nondestructive axial compression test at 7 and 25° of valgus stress, respectively. Then axial cyclic loading test with 1000N was applied for 1000 cycles, and interfragmentary displacement was measured with Fastrak magnetic tracking system (Polhemus, Colchester, VT, USA). Finally, destructive axial compression test was conducted at 7°of valgus stress.

RESULTS

Axial stiffness showed that group B had a 66% increase (879N/mm vs. 1461N/mm, P<0.01) at 7° valgus and a 46% increase (1611N/mm vs. 2349N/mm, P<0.01) at 25° valgus in comparison with group A. Interfragmentary fracture displacement after cyclic loading was significantly less for group B compared with group A (0.34 vs 0.13mm, P=0.0016). For axial failure load, there was 42% increase in group B compared with group A (2602N/mm vs. 3686N/mm, P=0.0023).

CONCLUSIONS

Our study demonstrates that the addition of a cerclage wire to inverted triangle triple screws provides substantial improvement in mechanical performance regarding fixation of vertically oriented femoral neck fractures when compared with the conventional construct. Our study provides support from a mechanical analysis perspective for the reported clinical usefulness of the cerclage wire.

Osteonecrosis of the femoral head, nonunion and potential risk factors in Pauwels grade-3 femoral neck fractures: A retrospective cohort study

The present study was to analyze clinical outcome of Pauwels grade-3 femoral neck fractures treated by different surgical techniques. Potential risk factors associated with nonunion and osteonecrosis of the femoral head (ONFH) were investigated as well. The retrospective study comprised of 67 sequential patients treated between January 2008 and December 2011. Patients with Pauwels grade-3 femoral neck fractures were treated by operative reduction and internal fixation. Cannulated screws (CS) were used in 46 patients, dynamic hip screw plus CS (DHS+CS) in 14, and locking compression plate (LCP) for proximal femur in 7. Reduction quality was assessed according to Haidukewych criteria. Postoperative radiographic examinations were conducted to observe fracture healing. Fracture displacement, comminution, fashion of internal fixation, and the sliding effect were analyzed, regarding the incidence of nonunion and ONFH. All patients had a follow-up of 21.6 ± 6.0 months on average. The phenomenon of sliding effect was observed in 16 cases (23.9%). In terms of reduction quality, 64 cases were graded as excellent, 2 were good, and 1 was poor. ONFH was presented in 15 cases (22.4%) and nonunion was found in 8 (11.9%), with 1 patient had ONFH and nonunion concomitantly. Profound hip contour was preserved in 45 cases (67.2%). The fashion of internal fixation yielded different results regarding ONFH and nonunion, whereas the effects of fracture displacement, comminution, and the sliding effect were not significant. ONFH and nonunion were common complications following Pauwels grade-3 femoral neck fractures. Higher incidence of ONFH in DHS+CS and of nonunion in the LCP group should be noted.

Tips and tricks for ORIF of displaced femoral neck fractures in the young adult patient

Femoral neck fractures in the young adult are a less common, but potentially functionally significant injury commonly occurring after high-energy trauma. The management goals of these injuries are the maintenance of a native hip joint absent avascular necrosis and nonunion. The primary determinant to this end is an anatomic reduction in displaced fractures with stable fixation. In this paper, the authors provide a set of technical tips and tricks to aid orthopedic surgeons in the surgical management of these injuries while reviewing the most recent literature available to inform clinical decision making. The paper includes the recommendations of the authors from the Denver Health Orthopaedic Trauma Service.