Screw-blade fixation systems in Pauwels three femoral neck fractures: a biomechanical evaluation

Comparison of dynamic hip screw with anti-rotation screw and femoral neck system internal fixation for the treatment of garden II-IV type femoral neck fractures

BACKGROUND

Femoral neck fractures, which are fractures occurring from the femoral head to the base of the femoral neck, are prevalent in the elderly population. With the progression of societal aging, the incidence of femoral neck fractures has been steadily increasing, making it a significant global issue that urgently needs to be addressed.

OBJECTIVE

To compare the efficacy and safety of dynamic hip screw (DHS) with anti-rotation screw and femoral neck system (FNS) internal fixation for the treatment of Garden II-IV type femoral neck fractures.

METHODS

A total of 90 patients with Garden II-IV type femoral neck fractures were randomly assigned to either the control group (n= 45) treated with DHS and anti-rotation screw or the experimental group (n= 45) treated with FNS. Surgical outcomes, including incision size, blood loss, operation time, fluoroscopy frequency, and fracture healing time, were compared. Postoperative complication rates, reoperation rates, Harris scores, and visual analogue scale (VAS) scores were also assessed.

RESULTS

The experimental group demonstrated significantly reduced incision length, blood loss, operation time, and fluoroscopy frequency compared to the control group (P< 0.01). No significant differences were observed in fracture healing time, Garden classification, or fracture reduction outcomes between the two groups (P> 0.05). At 6 months post-treatment, both groups showed significant improvements in Harris scores and VAS scores compared to pre-treatment (P< 0.05), with no significant differences between the groups (P> 0.05). The rates of internal fixation failure, nonunion, and avascular necrosis of the femoral head, as well as overall incidence of postoperative complications and reoperation rates, showed no significant differences between the two groups (P> 0.05).

CONCLUSIONS

Both DHS with anti-rotation screw and FNS internal fixation demonstrated comparable efficacy and safety profiles in the treatment of Garden II-IV type femoral neck fractures. The experimental group showed advantages in terms of reduced incision length, blood loss, operation time, and fluoroscopy frequency, while maintaining similar clinical outcomes and complication rates.

Finite Element Analysis of Six Internal Fixations in the Treatment of Pauwels Type III Femoral Neck Fracture

OBJECTIVE

The current investigation sought to utilize finite element analysis to replicate the biomechanical effects of different fixation methods, with the objective of establishing a theoretical framework for the optimal choice of modalities in managing Pauwels type III femoral neck fractures.

METHODS

The Pauwels type III fracture configuration, characterized by angles of 70°, was simulated in conjunction with six distinct internal fixation methods, including cannulated compression screw (CCS), dynamic hip screw (DHS), DHS with de-rotational screw (DS), CCS with medial buttress plate (MBP), proximal femoral nail anti-rotation (PFNA), and femoral neck system (FNS). These models were developed and refined using Geomagic and SolidWorks software. Subsequently, finite element analysis was conducted utilizing Ansys software, incorporating axial loading, torsional loading, yield loading and cyclic loading.

RESULTS

Under axial loading conditions, the peak stress values for internal fixation and the femur were found to be highest for CCS (454.4; 215.4 MPa) and CCS + MBP (797.2; 284.2 MPa), respectively. The corresponding maximum and minimum displacements for internal fixation were recorded as 6.65 mm for CCS and 6.44 mm for CCS + MBP. When subjected to torsional loading, the peak stress values for internal fixation were highest for CCS + MBP (153.6 MPa) and DHS + DS (72.8 MPa), while for the femur, the maximum and minimum peak stress values were observed for CCS + MBP (119.3 MPa) and FNS (17.6 MPa), respectively. Furthermore, the maximum and minimum displacements for internal fixation were measured as 0.249 mm for CCS + MBP and 0.205 mm for PFNA. Additionally, all six internal fixation models showed excellent performance in terms of yield load and fatigue life.

CONCLUSION

CCS + MBP had the best initial mechanical stability in treatment for Pauwels type III fracture. However, the MBP was found to be more susceptible to shear stress, potentially increasing the risk of plate breakage. Furthermore, the DHS + DS exhibited superior biomechanical stability compared to CCS, DHS, and PFNA, thereby offering a more conducive environment for fracture healing. Additionally, it appeared that FNS represented a promising treatment strategy, warranting further validation in future studies.

Proximal Femur Fractures - How Decisive are Reduction and the Chosen Implant?

Proximal femoral fractures are frequent and complex injuries requiring prompt and targeted care. Numerous treatment strategies have been described, some of which have been assessed and clinically implemented clinically. The aim of surgical is always the restoration of a pain-free and stable extremity. Mostly elderly patients are affected and treatment is associated with high postoperative complications and mortality rates. With increasing numbers of patients, the topic is of great medical and economic relevance. In this work, the choice of implants for the osteosynthesis of proximal femoral fractures - as depending on the fracture type - will be examined, as based on a review of current literature. Standard care includes cannulated screws, sliding hips screws and cephalomedullary nails. In addition, the influence of implant positioning, fracture reduction and additional measures such as cement augmentation are evaluated and discussed. Careful fracture reduction and the quality of implant positioning are paramount in order to avoid complications.

Exploring the displacement characteristics of Garden III femoral neck fractures and the reliability, validity, and value of the anteroposterior Garden Index in assessing displacement severity

BACKGROUND

Femoral neck fractures represent a significant public health concern, particularly in the elderly population. A thorough understanding and assessment of these fractures are deemed essential for optimal treatment and management. Displacement characteristics of Garden III femoral neck fractures were explored in this study, and the reliability, validity, and clinical utility of the anteroposterior Garden Index in evaluating displacement severity were investigated.

METHODS

Patients diagnosed with Garden III femoral neck fractures were included in this study. The anteroposterior Garden Index was computed from X-ray images by three experienced orthopedic doctors. Additionally, the contact area of the fracture endpoint and displacement of the femoral neck were evaluated using 128-slice 3D CT scans. Inter-observer and retest reliability of the Garden Index measurements were assessed, along with its correlation with CT measurements.

RESULTS

In this study, a total of 110 patients with Garden III femoral neck fractures were analyzed, showcasing an almost equal gender distribution and an age range spanning from 20 to 88 years. An average Garden Index of 135° (± 16°) was observed. The intra-observer repeatability of the Garden Index was found to exceed 90%. A significant positive correlation was identified between the Garden Index and the contact surface area of the fracture endpoint (r = 0.82, P < 0.001), while a significant negative correlation was noted with the upward displacement of the femoral neck (r = - 0.79, P < 0.001).

CONCLUSIONS

The anteroposterior Garden Index has been demonstrated to have promising potential as a reliable and valid tool for assessing the displacement severity of Garden III femoral neck fractures. Nonetheless, further research is needed to elucidate its relationship with other fracture characteristics and to enhance its criterion and construct validity.

Biomechanical evaluation of two modified intramedullary fixation system for treating unstable femoral neck fractures: A finite element analysis

Purpose: The existing implants for fixation of femoral neck fractures have poor biomechanical stability, so the failure rate is high. We designed two modified intramedullary implants for treating unstable femoral neck fractures (UFNFs). We tried to improve the biomechanical stability of fixation by shortening the moment and reducing stress concentration. Each modified intramedullary implant was compared with cannulated screws (CSs) through finite element analysis (FEA). Methods: Five different models were included: three cannulated screws (CSs, Model 1) in an inverted triangle configuration, the dynamic hip screw with an anti-rotation screw (DHS + AS, Model 2), the femoral neck system (FNS, Model 3), the modified intramedullary femoral neck system (IFNS, Model 4), and the modified intramedullary interlocking system (IIS, Model 5). Three-dimensional (3D) models of femur and implants were constructed by using 3D modelling software. Three load cases were simulated to assess the maximal displacement of models and fracture surface. The maximal stress at the bone and implants was also evaluated. Results: FEA data showed that Model 5 had the best performance in terms of maximum displacement while Model 1 had the worst performance for this index under axial load of 2100 N. With respect to Maximum stress, Model 4 had the best performance while Model 2 had the worst performance under axial load. The general trends under bending and torsion load were consistent with that under axial load. Our data demonstrated that the two modified intramedullary implants exhibited the best biomechanical stability, followed by FNS and DHS + AS, and then three cannulated screws in axial, bending, and torsion load cases. Conclusion: The two modified intramedullary designs showed the best biomechanical performance among the five implants included in this study. Therefore, this might provide some new options for trauma surgeons to deal with unstable femoral neck fractures.

Combined Deflection Angle Classification: A Novel Typing System of Adult Femoral Neck Fracture

OBJECTIVE

Femoral neck fracture (FNF) is a common clinical trauma with high mortality and disability rates. Furthermore, its incidence increases exponentially with increasing age. Existing classifications have some disadvantages. Thus, this study aimed to establish a novel typing system for FNF.

METHODS

We retrospectively analyzed all adult patients with FNF admitted to our hospital between December 2015 and November 2017 for cannulated screw internal fixation. The study population was divided into the femoral varus offset group (VAR) and the valgus offset group (VAL). The data collected included sex, age, affected side, injury mode, body mass index, complications, pelvic incidence (PI), hip deflection angle (HDA), combined deflection angle (CDA), and neck shaft angle. Statistical analysis was conducted to determine the correlation between complications and deviation angles. A novel typing system was developed and compared with the Garden classification to detect its superiority.

RESULTS

A total of 108 patients were recruited, with 59 patients in the VAR and 49 patients in the VAL groups. The incidence of complications in the VAR group was significantly higher than that in the VAL group (P < 0.05). Moreover, there were more male participants in the VAR group. Compared with the VAL group, the VAR group had significantly higher PI, HDA, and CDA (P < 0.05). The CDA classification (CDAC) was defined, with CDA as the main criterion and HDA as the supplementary criterion. Furthermore, there was a hierarchical correlation between the actual incidence of complications and the typing level, which was increased in CDAC but not in the Garden classification. This showed that CDAC was more accurate.

CONCLUSION

A novel typing system, CDAC, for FNF was established, which was more accurate than the Garden classification. We suggest combining CDAC and Garden classifications for the preoperative diagnosis, treatment selection, and prognostic evaluation for patients with FNF.

High Percentage of Complications and Re-Operations Following Dynamic Locking Plate Fixation with the Targon® FN for Intracapsular Proximal Femoral Fractures: An Analysis of Risk Factors

The ideal surgical treatment of femoral neck fractures remains controversial. When treating these fractures with internal fixation, many fixation constructs exist. The primary aim of this study was to evaluate the incidence and specific risk factors associated with complication and re-operation following fixation of intracapsular proximal femoral fractures using the Targon-FN system (B.Braun Melsungen AG). A secondary aim was to identify if lateral prominence of the implant relative to the lateral border of the vastus ridge was a specific risk factor for elective plate removal. Methodically, a retrospective case series was conducted of all consecutive adult patients treated at a single level 1 trauma center in Switzerland for an intracapsular proximal femoral fracture with the Targon-FN. Demographic data were collected. Patients with a follow-up of less than three months were excluded. Complications as well as plate position were recorded. Statistical analysis to identify specific risk factors for re-operation and complications was performed. In result, a total of 72 cases with intracapsular femoral neck fractures were treated with the Targon-FN locking plate system between 2010 and 2017. Thirty-four patients (47.2%) experienced one or more complications. The most common complication was mechanical irritation of the iliotibial band (ITB) (23.6%, n = 17). Complications included intraarticular screw perforation (6.9%, n = 5), avascular necrosis (5.6%, n = 4), non-union (5.6%, n = 4) among others. In total, 46 re-operations were required. Younger age, fracture displacement and time to postoperative weight bearing were identified as risk factors for re-operation. In conclusion, intracapsular femoral neck fractures treated with the Targon-FN system resulted in a high rate of post-operative complication and re-operation. Statistical analysis revealed patient age, fracture displacement, time to postoperative full weight bearing were risk factors for re-operation. The main limitation is the limited number of cases and a short follow-up of less than 12 months in a subgroup of our patients.

The incidence of focal osteonecrosis of the femoral head and its impact on conversion hip arthroplasty after screw fixation of femoral neck fractures: a multicenter retrospective study based on postoperative magnetic resonance imaging

PURPOSE

Osteonecrosis of the femoral head (ONFH) and subsequent head collapse is a major concern after internal fixation of femoral neck fracture (FNF). Previous studies focused on ONFH incidence using plain radiography; postoperative magnetic resonance imaging (MRI) was rarely performed. We performed a multicenter retrospective study to investigate the incidence of ONFH and the need for conversion hip arthroplasty after FNF screw fixation.

METHODS

We reviewed 195 patients who underwent screw fixation during closed FNF reduction between 2012 and 2017 at three institutions. Except for patients who did not consent to MRI, all patients underwent postoperative MRI either 1-3 years after screw fixation. The occurrence of ONFH was investigated through plain radiography and MRI.

RESULTS

Thirty patients were diagnosed with ONFH through plain radiography, and an additional 33 patients were diagnosed with MRI, resulting in a total of 63 patients (32.3%) diagnosed with ONFH. The mean time to ONFH diagnosis was 18.9 months and the conversion rate to hip arthroplasty was 10.2%. Of the 33 patients who were normal on hip radiography but exhibited ONFH on MRI, all had small focal lesions not associated with head collapse at the last follow-up. The ONFH group diagnosed through plain radiography had more unstable FNFs than the group diagnosed through MRI.

CONCLUSION

Although postoperative MRI revealed a higher incidence of ONFH after FNF screw fixation than reported previously, the small focal MRI lesions were not associated with increased risks of femoral head collapse or conversion to arthroplasty.

Impact of Anterior Malposition and Bone Cement Augmentation on the Fixation Strength of Cephalic Intramedullary Nail Head Elements

Background and Objectives: Intramedullary nailing of trochanteric fractures can be challenging and sometimes the clinical situation does not allow perfect implant positioning. The aim of this study was (1) to compare in human cadaveric femoral heads the biomechanical competence of two recently launched cephalic implants inserted in either an ideal (centre-centre) or less-ideal anterior off-centre position, and (2) to investigate the effect of bone cement augmentation on their fixation strength in the less-ideal position. Materials and Methods: Fourty-two paired human cadaveric femoral heads were assigned for pairwise implantation using either a TFNA helical blade or a TFNA screw as head element, implanted in either centre-centre or 7 mm anterior off-centre position. Next, seven paired specimens implanted in the off-centre position were augmented with bone cement. As a result, six study groups were created as follows: group 1 with a centre-centre positioned helical blade, paired with group 2 featuring a centre-centre screw, group 3 with an off-centre positioned helical blade, paired with group 4 featuring an off-centre screw, and group 5 with an off-centre positioned augmented helical blade, paired with group 6 featuring an off-centre augmented screw. All specimens were tested until failure under progressively increasing cyclic loading. Results: Stiffness was not significantly different among the study groups (p = 0.388). Varus deformation was significantly higher in group 4 versus group 6 (p = 0.026). Femoral head rotation was significantly higher in group 4 versus group 3 (p = 0.034), significantly lower in group 2 versus group 4 (p = 0.005), and significantly higher in group 4 versus group 6 (p = 0.007). Cycles to clinically relevant failure were 14,919 ± 4763 in group 1, 10,824 ± 5396 in group 2, 10,900 ± 3285 in group 3, 1382 ± 2701 in group 4, 25,811 ± 19,107 in group 5 and 17,817 ± 11,924 in group 6. Significantly higher number of cycles to failure were indicated for group 1 versus group 2 (p = 0.021), group 3 versus group 4 (p = 0.007), and in group 6 versus group 4 (p = 0.010). Conclusions: From a biomechanical perspective, proper centre-centre implant positioning in the femoral head is of utmost importance. In cases when this is not achievable in a clinical setting, a helical blade is more forgiving in the less ideal (anterior) malposition when compared to a screw, the latter revealing unacceptable low resistance to femoral head rotation and early failure. Cement augmentation of both off-centre implanted helical blade and screw head elements increases their resistance against failure; however, this effect might be redundant for helical blades and is highly unpredictable for screws.

Biomechanical and clinical evaluation of interlocking hip screw in Pauwels Ⅲ femoral neck fractures: A comparison with inverted triangle cannulated screws

Purpose: To compare biomechanical and clinical properties of the novel internal fixation Interlocking Hip Screw (IHS) and conventional inverted triangle cannulated screws (ITCS) for treatment of Pauwels Ⅲ femoral neck fractures. Methods: Twenty synthetic femurs were osteotomized to simulate 70° Pauwels Ⅲ femoral neck fractures and randomly divided into two groups: Group IHS and Group ITCS. Specimens were loaded in quasi-static ramped and cyclical compression testing in 25° adduction to analyze for axial stiffness, failure load, and interfragmentary displacement. 21 matched patients with Pauwels Ⅲ femoral neck fracture who received closed reduction and internal fixation from January 2020 to January 2021 in both Group IHS and Group ITCS. Demographic data, time to surgery, operating duration, intraoperative blood loss, number of fluoroscopies, length of hospital stay, fracture healing time, Harris Hip Score (HHS), the score of Visual Analogue Scale (VAS) and complications such as nonunion, avascular necrosis, and femoral neck shortening were compared. Results: All specimens in the two groups survived in the axial and cyclical compression test. The axial stiffness was significantly higher for Group IHS (277.80 ± 26.58 N/mm) versus Group ITCS (205.33 ± 10.46 N/mm), p < 0.05. The maximum failure loading in Group IHS performed significantly higher than in Group ITCS (1,400.48 ± 71.60 N versus 996.76 ± 49.73 N, p < 0.05). The interfragmentary displacement of the cyclic loading test for Groups IHS and Group ITCS was 1.15 ± 0.11 mm and 1.89 ± 0.14 mm, respectively, p < 0.05. No significant difference was found in terms of demographic data, time to surgery, intraoperative blood loss, length of hospital stay and the occurrence of nonunion and avascular necrosis between groups. Shorter operating duration and fewer intraoperative fluoroscopic views were noticed using IHS compare to ITCS, p < 0.05. The HHS was 72.14 ± 5.76 and 86.62 ± 5.01 in Group IHS, and was 67.29 ± 5.27 and 81.76 ± 5.13 in Group ITCS at 3-month and 6-month follow-up, respectively, p < 0.05. The magnitude of femoral neck shortening was significantly lower in Group IHS compared to Group ITCS (4.80 ± 1.03 mm versus 5.56 ± 1.21 mm, p < 0.05). Conclusion: Our study demonstrated that IHS provided better biomechanical and clinical performance due to its unique biological and biomechanical mechanisms, compared with ITCS. Thus, IHS is a feasible alternative to ITCS for the fixation of Pauwels Ⅲ femoral neck fractures.

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).

[Research progress in biomechanics of common internal fixation for femoral neck fracture]

OBJECTIVE

To summarize the characteristics and biomechanical research progress of common internal fixation for femoral neck fractures in recent years, so as to provide reference to clinical treatment of femoral neck fracture.

METHODS

The domestic and foreign relevant literature on biomechanics of internal fixation of femoral neck fracture in recent years was reviewed, and the biomechanical research progress was summarized.

RESULTS

Among the internal fixations currently used in the treatment of femoral neck fractures, three cannulated screws can provide sliding compression at the end of the fracture, but the shear resistance is weak, and the risk of long-term internal fixation failure is high; dynamic hip screw and proximal femoral locking plate have excellent angle stability and overall strength; medial buttress plate can transform vertical shear force into compressive stress to promote fracture healing and produce a certain anti-rotation effect; femoral neck system can support the fracture in multi-axial direction, with excellent anti-rotation and anti-shortening properties; and cephalomedullary nails have high overall strength and failure load. Different internal fixations have their own indications due to differences in structure and biomechanics.

CONCLUSION

At present, there is no detailed standard guidance of internal fixation selection. Clinically, the appropriate treatment should be selected according to the fracture types of patients.

Biomechanical comparison of the femoral neck system versus InterTan nail and three cannulated screws for unstable Pauwels type III femoral neck fracture

BACKGROUND

There are a variety of internal fixation methods for unstable femoral neck fractures (FNFs), but the best method is still unclear. Femoral neck system (FNS) is a dynamic angular stabilization system with cross screws, and is a new internal fixation implant designed for minimally invasive fixation of FNFs. In this study, we conducted a biomechanical comparison of FNS, InterTan nail and three cannulated screws for the treatment of Pauwels III FNFs and investigate the biomechanical properties of FNS.

METHODS

A total of 18 left artificial femurs were selected and randomly divide into Group A (fixation with FNS), Group B (fixation with InterTan nail) and Group C (fixation with three cannulated screws), with 6 specimens in each group. After creating Pauwels type III FNF models, the specimens in each were tested with non-destructive quasi-static tests, including torsion, A-P bending and axial compression tests. The average slope of the linear load-deformation curve obtained from quasi-static tests defines the initial torsional stiffness, A-P bending stiffness, and axial compression stiffness. After cyclic loading test was applied, the overall deformation of models and local deformation of implant holes in each group were assessed. The overall deformation was estimated as the displacement recorded by the software of the mechanical testing apparatus. Local deformation was defined as interfragmental displacement. Data were analyzed by one-way analysis of variance (ANOVA) followed by Bonferroni post hoc test using the SPSS software (version 24.0, IBM, New York, NY, USA). Correlation analysis was performed using Pearson's correlation analysis.

RESULTS

Group B exhibited significantly higher axial stiffness and A-P bending stiffness than the other two groups (P < 0.01), while Group A had significantly higher axial stiffness and A-P bending stiffness than Group C (P < 0.01). Groups A and B exhibited significantly higher torsional stiffness than Group C (P < 0.01), no statistical significance was observed between Groups A and B (P > 0.05). Group B exhibited significantly lower overall and local deformations than the other two groups (P < 0.01), while Group A had significantly lower overall and local deformations than Group C (P < 0.01). Correlation analysis revealed positive correlation between axial stiffness and A-P bending stiffness (r = 0.925, P < 0.01), torsional stiffness (r = 0.727, P < 0.01), between torsional stiffness and A-P bending stiffness; negative correlation between overall, local deformations and axial stiffness (r = - 0.889, - 0.901, respectively, both P < 0.01), and positive correlation between the two deformations (r = - 0.978, P < 0.01).

CONCLUSION

For fixation of unstable FNFs, InterTan nail showed the highest axial stiffness and A-P bending stiffness, followed by FNS, and then three cannulated screws. Torsional stiffness of FNS was comparable to that of the InterTan nail. FNS, as a novel minimally invasive implant, can create good mechanical environment for the healing of unstable FNFs. Clinical studies are needed to confirm the potential advantages of FNS observed in this biomechanical study.

Mechanical effects of surgical variations in the femoral neck system on Pauwels type III femoral neck fracture : a finite element analysis

AIMS

In this study, we aimed to explore surgical variations in the Femoral Neck System (FNS) used for stable fixation of Pauwels type III femoral neck fractures.

METHODS

Finite element models were established with surgical variations in the distance between the implant tip and subchondral bone, the gap between the plate and lateral femoral cortex, and inferior implant positioning. The models were subjected to physiological load.

RESULTS

Under a load of single-leg stance, Pauwels type III femoral neck fractures fixed with 10 mm shorter bolts revealed a 7% increase of the interfragmentary gap. The interfragmentary sliding, compressive, and shear stress remained similar to models with bolt tips positioned close to the subchondral bone. Inferior positioning of FNS provided a similar interfragmentary distance, but with 6% increase of the interfragmentary sliding distance compared to central positioning of bolts. Inferior positioning resulted in a one-third increase in interfragmentary compressive and shear stress. A 5 mm gap placed between the diaphysis and plate provided stability comparable to standard fixation, with a 7% decrease of interfragmentary gap and sliding distance, but similar compressive and shear stress.

CONCLUSION

Finite element analysis with FNS on Pauwels type III femoral neck fractures revealed that placement of the bolt tip close to subchondral bone provides increased stability. Inferior positioning of FNS bolt increased interfragmentary sliding distance, compressive, and shear stress. The comparable stability of the fixation model with the standard model suggests that a 5 mm gap placed between the plate and diaphysis could viably adjust the depth of the bolt. Cite this article: Bone Joint Res 2022;11(2):102-111.

Impact of Bone Cement Augmentation on the Fixation Strength of TFNA Blades and Screws

Background and Objectives: Hip fractures constitute the most debilitating complication of osteoporosis with steadily increasing incidences in the aging population. Their intramedullary nailing can be challenging because of poor anchorage in the osteoporotic femoral head. Cement augmentation of Proximal Femoral Nail Antirotation (PFNA) blades demonstrated promising results by enhancing cut-out resistance in proximal femoral fractures. The aim of this study was to assess the impact of augmentation on the fixation strength of TFN-ADVANCEDTM Proximal Femoral Nailing System (TFNA) blades and screws within the femoral head and compare its effect when they are implanted in centre or anteroposterior off-centre position. Materials and Methods: Eight groups were formed out of 96 polyurethane low-density foam specimens simulating isolated femoral heads with poor bone quality. The specimens in each group were implanted with either non-augmented or cement-augmented TFNA blades or screws in centre or anteroposterior off-centre positions, 7 mm anterior or posterior. Mechanical testing was performed under progressively increasing cyclic loading until failure, in setup simulating an unstable pertrochanteric fracture with a lack of posteromedial support and load sharing at the fracture gap. Varus-valgus and head rotation angles were monitored. A varus collapse of 5° or 10° head rotation was defined as a clinically relevant failure. Results: Failure load (N) for specimens with augmented TFNA head elements (screw/blade centre: 3799 ± 326/3228 ± 478; screw/blade off-centre: 2680 ± 182/2591 ± 244) was significantly higher compared with respective non-augmented specimens (screw/blade centre: 1593 ± 120/1489 ± 41; screw/blade off-centre: 515 ± 73/1018 ± 48), p < 0.001. For both non-augmented and augmented specimens failure load in the centre position was significantly higher compared with the respective off-centre positions, regardless of the head element type, p < 0.001. Augmented off-centre TFNA head elements had significantly higher failure load compared with non-augmented centrally placed implants, p < 0.001. Conclusions: Cement augmentation clearly enhances the fixation stability of TFNA blades and screws. Non-augmented blades outperformed screws in the anteroposterior off-centre position. Positioning of TFNA blades in the femoral head is more forgiving than TFNA screws in terms of failure load.

Intracapsular Femoral Neck Fractures-A Surgical Management Algorithm

Background and Objectives: Femoral neck fractures are common and constitute one of the largest healthcare burdens of the modern age. Fractures within the joint capsule (intracapsular) provide a specific surgical challenge due to the difficulty in predicting rates of bony union and whether the blood supply to the femoral head has been disrupted in a way that would lead to avascular necrosis. Most femoral neck fractures are treated surgically, aiming to maintain mobility, whilst reducing pain and complications associated with prolonged bedrest. Materials and Methods: We performed a narrative review of intracapsular hip fracture management, highlighting the latest advancements in fixation techniques, generating an evidence-based algorithm for their management. Results: Multiple different fracture configurations are encountered within the category of intracapsular hip fractures, with each pattern having different optimal surgical strategies. Additionally, these injuries typically occur in patients where further procedures due to operative complications are associated with a considerable increase in mortality, highlighting the need for choosing the correct index operation. Conclusions: Factors such as pathological causes for the fracture, pre-existing symptomatic osteoarthritis, patient’s physiological age and fracture displacement all need to be considered when choosing optimal management.

Medial femoral plate with cannulated screw for Pauwels type III femoral neck fracture: A meta-analysis

BACKGROUND

Femoral neck fractures often occur in the elderly, which usually results in hip pain.

OBJECTIVE

The purpose of this study was to evaluate the difference in the treatment of Pauwels type III femoral neck fractures with medial femoral support plate combined with cannulated screws and cannulated screws alone.

METHODS

PubMed, ScienceDirect, China Academic Journals Full-text Database (CNKI), Wanfang Database, Chinese Biomedical Literature Database (CBM), Embase and Cochrane Library were used to collect clinical controlled trials of the medial femoral support plate combined with hollow screw internal fixation and simple hollow screw internal fixation for Pauwels type III femoral neck fracture.

RESULTS

Seven articles (n= 409 cases) were evaluated for quality and included in this meta-analysis. Four hundred and nine patients with Pauwels type III femoral neck fractures were included: 202 in the experimental group and 207 in the control group. The results showed that, compared with simple hollow screw internal fixation, the medial femoral support plate combined with hollow screw internal fixation has a longer operation time (MD= 23.05, 95% CI= 13.86-32.24), and more intraoperative blood loss (MD= 91.55, 95% CI= 50.72-132.39), shorter healing time (MD=-1.48, 95% CI (-1.71, -1.26)), lower incidence of complications (RR= 0.34, 95% CI= 0.19-0.61), lower VAS score (MD=-1.28, 95% CI (-1.83, -0.72)), and higher Harris score (MD= 8.49, 95% CI (4.15, 12.83)).

CONCLUSION

Medial femoral plate combined with cannulated screw for Pauwels type III femoral neck fracture can shorten healing time, reduce postoperative complications, and improve the postoperative Harris score.

Screw-blade fixation systems for implant anchorage in the femoral head: Horizontal blade orientation provides superior stability

OBJECTIVES

Despite continual improvement in the methods and devices used for treatment of proximal femoral fractures, unacceptably high failure rates remain. Novel screw-blade implant systems, combining a lag screw with a blade - the latter adding rotational stability to the femoral head - offer improvement of osseous purchase, especially in osteoporotic bone. The aim of this study was to compare biomechanically the head element (HE) anchorage of two screw-blade implant systems differing in blade orientation in the femoral head - vertical versus horizontal.

METHODS

Twenty paired human cadaveric femoral heads were assigned to four groups (n = 10), implanted with either Rotationally Stable Screw-Anchor HE (RoSA-HE, vertical blade orientation) or Gamma3 Rotation Control Lag Screw (Gamma-RC, horizontal blade orientation) in center or off-center position, and biomechanically tested until failure under progressively increasing cyclic loading at 2 Hz.

RESULTS

Cycles to failure and failure load were significantly higher for Gamma-RC versus RoSA-HE in center position and not significantly different between them in off-center position, p = 0.03 and p = 0.22, respectively. In center position, the progression of both rotation around implant axis and varus deformation over time demonstrated superiority of the implant with horizontal versus vertical blade orientation. Compared with center positioning, off-center implant placement led to a significant decrease in stiffness, cycles to failure and failure load for Gamma-RC, but not for RoSA-HE, p < 0.01 and p = 0.99, respectively.

CONCLUSION

Horizontal blade orientation of screw-blade implant systems demonstrates better anchorage in the femoral head versus vertical blade orientation in center position. As the stability of the implant system with horizontal blade orientation drops sharply in off-center position, central insertion is its placement of choice.

Cement augmentation for trochanteric femur fractures: A meta-analysis of randomized clinical trials and observational studies

Introduction

To date, it is unclear what the clinical benefit of cement augmentation in fixation for trochanteric fractures is. The aim of this meta-analysis is to compare cement augmentation to no augmentation in fixation of trochanteric femur fractures in the elderly patients (>65 years) following low energy trauma.

Methods

PubMed/Medline/Embase/CENTRAL/CINAHL were searched for both randomized clinical trials (RCT) and observational studies comparing both treatments. Effect estimates were pooled across studies using random effects models. Subgroup analysis was performed stratified by study design (RCTs and observational studies). The primary outcome is overall complication rate. Secondary outcomes include re-operation rate, mortality, operation duration, hospital stay, general quality of life, radiologic measures and functional hip scores.

Results

A total of four RCT’s (437 patients) and three observational studies (293 patients) were included. The effect estimates of RCTs were equal to those obtained from observational studies. Cement augmentation has a significantly lower overall complication rate (28.3% versus 47.2%) with an odds ratio (OR) of 0.3 (95%CI 0.1–0.7). The occurrence of device/fracture related complications was the largest contributing factor to this higher overall complication rate in the non-augmented group (19.9% versus 6.0%, OR 0.2, 95%CI 0.1–0.6). Cement augmentation also carries a lower risk for re-interventions (OR 0.2, 95%CI 0.1–0.7) and shortens the hospital stay with 2 days (95%CI -2.2 to -0.5 days). The mean operation time was 7 minutes longer in the augmented group (95%CI 1.3–12.9). Radiological scores (lag screw/blade sliding mean difference -3.1mm, 95%CI -4.6 to -1.7, varus deviation mean difference -6.15°, 95%CI; -7.4 to -4.9) and functional scores (standardized mean difference 0.31, 95%CI 0.0–0.6) were in favor of cement augmentation. Mortality was equal in both groups (OR 0.7, 95%CI 0.4–1.3) and cement related complications were rare.

Conclusion

Cement augmentation in fixation of trochanteric femoral fractures leads to fewer complications, re-operations and shorter hospital stay at the expense of a slightly longer operation duration. Cementation related complications occur rarely and mortality is equal between treatment groups. Based on these results, cement augmentation should be considered for trochanteric fractures in elderly patients.

Biomechanical analysis for five fixation techniques of Pauwels-III fracture by finite element modeling

BACKGROUND AND OBJECTIVES

There are many fixation methods for Pauwels- III fracture, the most common implants are Locking Plate (LP), Dynamic Hip Screw (DHS), Multiple Lag Screw (MLS), and mixed fixture (DHS+MLS) implants, the common procedure is HemiArthroplasty (HA). However, how these fixtures biomechanically function is not clear. The aims of this study are to compare the mechanical behaviors of these five implants by finite element modeling and determinate the most suitable procedure for individuals with Pauwels- III fractures.

METHODS

We gathered 20 sets of femur images from CT scans in the *.dicom format first, and then processed them by using reverse engineering software programs, such as Mimics, Geomagic Studio, UG-8, Pro-Engineer and HyperMesh. Finally, we assembled and analyzed the five types of fixture models, the LP, DHS, MLS, DHS+LS and HA models, by AnSys.

RESULTS

These numerical models of Pauwels III fractures, including fixators and a simulative HA, were validated by a previous study and a cadaver test. Our analytical findings include the following: the displacements of all fixtures were between 0.3801 and 1.0834 mm, and the differences were not statistically significantly different; the resulting average peaks in stress were e(Ha) = 43.859 ≤ d(LP) = 60.435 ≤ b(MLS) = 68.678 < c(LS+DHS) = 98.478 < a(DHS) = 248.595 in Mpa, indicating that the stress of DHS and DHS+LS are greater than those of LP, HA and MLS, while the last 3 models were not significantly different.

CONCLUSIONS

To optimize the treatment for Pauwels III factures clinically, HA and LP should be proposed.

Higher stability and more predictive fixation with the Femoral Neck System versus Hansson Pins in femoral neck fractures Pauwels II

Objectives

To evaluate the biomechanical performance of the Femoral Neck System (FNS) versus the Hansson Pin System (Hansson Pins) with two parallel pins in a Pauwels II femoral neck fracture model with posterior comminution.

Methods

Forty-degree Pauwels II femoral neck fractures AO 31-B2.1 with 15° posterior wedge were simulated in fourteen paired fresh-frozen human femora, followed by instrumentation with either FNS or Hansson Pins in pair-matched fashion. Implant positioning was quantified by measuring shortest implant distances to inferior cortex (DI) and posterior cortex (DP) on anteroposterior and axial X-rays, respectively. Biomechanical testing was performed in 20° adduction and 10° flexion with simulated iliopsoas muscle tension. Progressively increasing cyclic loading was applied until construct failure. Interfragmentary femoral head-to-shaft movements were measured with optical motion tracking.

Results

Cycles to 10° varus deformation were significantly higher for FNS (23007 ​± ​5496) versus Hansson Pins (17289 ​± ​4686), P ​= ​0.027. Cycles to 10° femoral head dorsal tilting (FNS: 12765 ​± ​3425; Hansson Pins: 13357 ​± ​6104) and cycles to 10° rotation around the femoral neck axis (FNS: 24453 ​± ​5073; Hansson Pins: 20185 ​± ​11065) were comparable between the implants, P ​≥ ​0.314. For Hansson Pins, the outcomes for varus deformation and dorsal tilting correlated significantly with DI and DP, respectively (P ​≤ ​0.047), whereas these correlations were not significant for FNS (P ​≥ ​0.310).

Conclusions

From a biomechanical perspective, by providing superior resistance against varus deformation and performing in a less sensitive way to variations in implant placement, the angular stable Femoral Neck System can be considered as a valid alternative to the Hansson Pin System for the treatment of Pauwels II femoral neck fractures.

Level of evidence

therapeutic, Level V.

The Translational potential of this article

The translational potential of this article is to compare the performance of the FNS with Hansson Pins in a AO 31-B2.1 fracture model featuring a 15 posterior wedge to show the implants behavior concerning the dorsal tilting tendency.

Increased stability by a novel femoral neck interlocking plate compared to conventional fixation methods. A biomechanical study in synthetic bone

BACKGROUND

Stable fixation promotes union in the common femoral neck fractures, but high non-union rates due to fixation failure remain with traditional fixations. To enhance stability, a plate interlocking pins, but without further fixation to femur has been developed. To our knowledge, no comparison to other conventional fixation methods has been performed. We tested the hypothesis that the novel implant biomechanically leads to a more stable femoral neck fixation.

METHODS

Fifty synthetic femurs with a cervical wedge osteotomy were allocated to intervention with three hook-pins interlocked in a plate (Hansson Pinloc® System) or standard fixations with a two-hole Dynamic Hip Screw® plate with an anti-rotational screw, three cannulated screws (ASNIS® III) or two screws (Olmed® or Cannulated Hip Screws®). Quasi-static non-destructive torsion around the neck, anteroposterior bending and vertical compression were tested to detect stiffness. The specimen's deformation was evaluated after cyclic compression simulating weight-bearing. Local deformation of implant channels was measured. Fixation failure was defined by fissure formation.

FINDINGS

Compared to the conventional implants all together, the interlocked pins enhanced mean stiffness 130% in torsion and 33% in bending (P < 0.001), while compressive stability was increased by a reduced deformation of 62% in average of the global test specimen and 95% decreased local implant channel deformation after cycling (P < 0.001). In comparisons with each of the standard fixations the interlocking pins revealed no signs of adverse effects.

INTERPRETATION

The novel femoral neck interlocking plate allowed dynamic compression and improved multi-directional stability compared to the traditional fixations.

Finite element analysis of a new plate for Pauwels type III femoral neck fractures

Background

Method

Result

Conclusion

A Comparison of Dynamic Hip Screw and Two Cannulated Screws in the Treatment of Undisplaced Intracapsular Neck Fractures-Two-Year Follow-Up of 453 Patients

One of the most common fractures is that of the intracapsular femoral neck; however, the optimal implant for head-preserving treatment remains controversial. The aim of the study was to compare the outcomes of treating undisplaced intracapsular femoral neck fractures with either the dynamic hip screw (DHS) or the double cannulated screw fixation (CSFN). This retrospective cohort study analysed the data of 453 patients, with a mean age of 76.9 years, whose intracapsular fractures were treated with the DHS or CSFN between 2005 and 2013. The analysis focused on the rates of revision surgeries and complications; however, the impact of confounding exogenous factors, such as smoking and alcohol, were also considered. No significant difference was observed between the revision rates of DHS and CSFN (15.0% vs. 13.1%; p = 0.565). According to the complication rate, the advantage in favour of the CSFN was not significant (20.5% vs. 13.1%, p = 0.038). The use of the DHS was associated with a 13 min longer surgery (p < 0.0001) and a one day longer hospitalization (p = 0.242). Excessive consumption of alcohol was associated with an increased incidence of avascular necrosis (18.6% vs. 8.7%, p = 0.035). The choice of implant showed no significant impact on rates of revision surgery and complications. In terms of socioeconomic factors, the fixation with two cannulated screws was more favourable, making it the more cost-effective and less stressful method.

Influence of reduced tip-apex distance on helical blade fixation-a biomechanical study

Migration profile of helical blades differs from conventional screw design. Tip-apex distance (TAD) greater than 25 mm is associated with early failure in hip screws. This study investigates the effect of a reduced TAD on helical blade fixation. Six pairs of human femoral heads were used. Bone mineral density (BMD) was determined by pQCT. Local bone quality was evaluated by breakaway torque. Helical blades were implanted with TAD of 20 mm (normal) and 6 mm (reduced). Specimens were cyclically tested under progressively increasing physiologic loading at 2 Hz with starting peak force of 1'000N, increasing by 0.1N/cycle. Implant migration was monitored by radiographs every 250 cycles. Paired Student's t-test and Spearman rank correlation coefficient were used for statistical evaluation (p < 0.05). Mean BMD was 246.7 mgHA/cm³ SD48.7 (normal), 244.3 mgHA/cm³ SD47.6 (reduced); p = 0.93. Mean breakaway torque was 3.59 Nm SD2.11 (normal), 3.72 Nm SD1.83 (reduced); p = 0.91. Number of cycles to failure (1 mm vertical migration) was 16'416 SD7972 (normal), 20'000 SD5232 (reduced); p = 0.38. They correlated significantly with BMD (p = 0.01;R²  = 0.91) and breakaway torque (p < 0.049; R²  = 0.814) (normal). Breakaway torque correlated significantly with BMD (p = 0.02; R²  = 0.898) (normal). In reduced TAD these parameters did not correlate significantly. Normal TAD resulted in failure in varus collapse (n = 6), whereas reduced TAD showed blade perforation (n = 3), rotation (n = 2), varus collapse (n = 1). Fixation stability of helical blades correlates with bone quality when implants are fixed in cancellous bone. Near cortical blade fixation might increase the risk of intraarticular blade perforation. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 9999:1-6, 2019.

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.

Is bone-cement augmentation of screw-anchor fixation systems superior in unstable femoral neck fractures? A biomechanical cadaveric study

OBJECTIVES

Improved fixation techniques with optional use of bone cements for implant augmentation have been developed to enhance stability and reduce complication rates after osteosynthesis of femoral neck fractures. This biomechanical study aimed to evaluate the effect of cement augmentation on implant anchorage and overall performance of screw-anchor fixation systems in unstable femoral neck fractures.

METHODS

Ten pairs of human cadaveric femora were used to create standardized femoral neck fractures (Pauwels type 3 fractures; AO/OTA 31-B2) with comminution and were fixed by means of a rotationally stable screw-anchor (RoSA) system. The specimens were assigned pairwise to two groups and either augmented with PMMA-based cement (Group 1, augmented) or left without such augmentation (Group 2, control). Biomechanical testing, simulating physiological loading at four distinct load levels, was performed over 10.000 cycles for each level with the use of a multidimensional force-transducer system. Data was analysed by means of motion tracking.

RESULTS

Stiffness, femoral head rotation, implant migration, femoral neck shortening, and failure load did not differ significantly between the two groups (p ≥ .10). For both groups, the main failure type was dislocation in the frontal plane with consecutive varus collapse). In the cement-augmented specimens, implant migration and femoral neck shortening were significantly dependent on bone mineral density (BMD), with higher values in osteoporotic bones. There was a correlation between failure load and BMD in cement-augmented specimens.

CONCLUSION

In screw-anchor fixation of unstable femoral neck fractures, bone-cement augmentation seems to show no additional advantages in regard to stiffness, rotational stability, implant migration, resistance to fracture displacement, femoral neck shortening or failure load.

Experimental validation of finite elements model in hip fracture and its clinical applicability

Fracture of the proximal extremity of the femur is the subject of research interest. The complexity of the bone framework and the structural inefficiency associated with ageing leave many variables yet to be understood from an experimental perspective. However, there is no clearly defined structural and biomechanical research model for hip fracture. The hypothesis of this paper is that it is possible to create a computational experimentation model that characterises the bone of the proximal extremity of the femur as a heterogeneous material from directly translating the mechanical parameters obtained from anatomical experimentation specimens.

MATERIAL AND METHOD

An experimental paper comparing real experimentation on cadavers and a numerical model based on finite element analysis (FEA). The variables uses were: the start point of the fracture, propagation of the fracture, progressive load and maximum load until fracture. The real mechanical parameters obtained from the anatomical specimens were translated to the computational model based on the relationship between the Hounsfield units of the high resolution CAT scan and the bone mineral density of each virtual element, whereas the propagation of the fracture was modelled by the research team's own computational design, reducing the mechanical properties of the damaged elements as the fracture line advanced.

RESULTS

The computational model was able to determine the start point of the fracture, with a slight tendency towards anatomical medialisation of this point compared to what happened experimentally. The degree of correlation was very high on comparing the real value of progressive deformation of the samples compared to that obtained by the computational model. Over 32 points analysed, a slope of 1.03 in lineal regression was obtained, with a relative error between the deformations of 16% and a Pearson's coefficient of R²=.99. The computational model slightly underestimated the maximum fracture load, with a relative error of approximately 10%.

CONCLUSION

The FEA computational model developed by this multi-disciplinary research team could be considered, as a whole, a complete FEA model of the proximal extremity of the femur with future clinical applicability since it was able to simulate and imitate the biomechanical behaviour of human femurs contrasted with a traditional experimental model made from anatomical specimens. On this basis, qualitative and quantitative interactions can be assessed which consolidate it as a powerful computational experimentation test bench for the human proximal femur.

Effect of cannulated screws with deep circumflex iliac artery-bone grafting in the treatment of femoral neck fracture in young adults

OBJECTIVES

Surgical treatment of femoral neck fracture in young adults is clinically challenging due to the high incidence of avascular necrosis of femoral head and fracture nonunion. The objective of this study is to evaluate the effectiveness of cannulated screws with deep circumflex iliac artery bone grafting (DCIABG) by comparing to the routinely used method in the treatment of femoral neck fracture in young adults.

METHODS

From March 2006 to December 2012, a total of 185 patients with femoral neck fracture were admitted to the hospital for internal fixation surgery, 103 patients (61 males and 42 females, mean age of 39.1 years) were treated with three cannulated screws with DCIABG (group A), and 82 patients (49 males and 33 females, mean age of 35.5 years) were treated with three cannulated screws without DCIABG (group B).

RESULTS

All patients were followed up for at least 24 months after the surgery. The patients in group A had a significantly higher Harris Hip Score (p < 0.001), shorter fracture healing time (p < 0.001), lower occurrence rate of avascular necrosis of femoral head (p = 0.008) and fracture nonunion (p = 0.012) compared to the patients in group B. However, the operation time and intraoperative blood loss were significantly lower in patients in group B than those in group A (p < 0.001).

CONCLUSIONS

Cannulated screws with DCIABG significantly reduced femoral head osteonecrosis and fracture nonunion. Therefore, it is a feasible and effective method in the treatment of young adult patients with femoral neck fracture.