Biomechanical performance of retrograde nail for supracondylar fractures stabilization

Torsional stability of fixation methods in basicervical femoral neck fractures: a biomechanical study

BACKGROUND

Basicervical femoral neck fracture is a rare proximal femur fracture with a high implant failure rate. Biomechanical comparisons between cephalomedullary nails (CMNs) and dynamic hip screws (DHSs) under torsion loading are lacking. This study compared the biomechanical performance of three fixations for basicervical femoral neck fractures under torsion load during early ambulation.

METHODS

The biomechanical study models used three fixations: a DHS, a DHS with an anti-rotation screw, and a short CMN. Finite element analysis was used to simulate hip rotation with muscle forces related to leg swing applied to the femur. The equivalent von Mises stress (EQV) on fixation, fragment displacement, and strain energy density at the proximal cancellous bone were monitored for fixation stability.

RESULTS

The EQV of the short CMN construct (304.63 MPa) was comparable to that of the titanium DHS construct (293.39 MPa) and greater than that of the titanium DHS with an anti-rotation screw construct (200.94 MPa). The proximal fragment displacement in the short CMN construct was approximately 0.13 mm, the greatest among the constructs. The risk of screw cutout for the lag screw in short CMNs was 3.1-5.8 times greater than that for DHSs and DHSs with anti-rotation screw constructs.

CONCLUSIONS

Titanium DHS combined with an anti-rotation screw provided lower fragment displacement, stress, and strain energy density in the femoral head than the other fixations under torsion load. Basicervical femoral neck fracture treated with CMNs may increase the risk of lag screw cutout.

The application of inverted lateral clavicle locking compression plate for medial clavicle fractures: biomechanical study and clinical implementation

BACKGROUND

There has been no absolute consensus on the optimal implant for fixation of medial clavicle fracture. The purpose of the present study was to test the biomechanical efficacy of inverted lateral clavicle locking compression plate (LCP-LC) in fixation of this specific fracture location by finite element analysis.

METHODS

Transverse and comminuted medial clavicle fracture simulated models stabilized by three different devices including inverted LCP-LC, superior clavicle LCP (LCP-SC), and dual reconstruction (LCP-RP) with LCP-SC were investigated biomechanical performance under three loading conditions, i.e., axial compression, inferior bending, and axial torsion.

RESULTS

EQV stress exhibited on implant and elastic strain at fracture site under inferior bending was greater than other loading cases. LCP-SC construct represented the greatest EQV stress and elastic strain. The inverted LCP-LC construct demonstrated lower EQV stress than the LCP-SC construct and was comparable to dual plating. Under axial compression and axial torsion, elastic strain produced from the inverted LCP-LC construct was comparable to dual plating, but greater than dual plating when subjected to inferior bending.

CONCLUSION

By the results of FE analysis, inverted LCP-LC could be a potential application for fixation of clavicle fracture with short medial fragment.

Nonvascularized fibular graft with locking screw fixation for metaphyseal bone loss of distal femur: biomechanical assessment validated by a clinical case series

BACKGROUND

The optimal modality to surgically treat significant bone loss of distal femur remains inconclusive. The objectives of the present study were to assess the mechanical performance of nonvascularized fibular graft (NVFG) with locking screw fixation in distal femur fixation construct by finite element analysis and to retrospectively describe the outcomes of the present technique in clinical cases.

METHODS

Four constructs which the fractured femur was stabilized by LCP-DF alone, dual plating, LCP-DF combined with NVFG, and LCP-DF combined with NVFG (LCP-DF-NVFG-S) with locking screw were assessed the biomechanical performance under physiological loads. For the clinical case series, 12 patients with open intercondylar fracture with metaphyseal bone loss of distal femur were operated by LCP-DF-NVFG-S. The collected data included fracture consolidation, length of NVFG, perioperative complications and objective clinical results.

RESULTS

LCP-DF-NVFG-S demonstrated lower implant equivalent von Mises stress (EQV) stress and better fracture stability than other constructs. A locking screw presented its essence in maintaining the NVFG in the required position and subsequently enhancing the fracture stability. In regard to the clinical series, all fractures were consolidated with an average duration of 27.8 weeks (range 20-32). An average NVFG length was 7.8 cm (range 6-12). No perioperative complication was demonstrated. By the Knee Society score, 1 was considered to be excellent, 9 to be good and 2 to be poor.

CONCLUSION

Based on the results of mechanical assessment and case series, LCP-DF-NVFG-S can be an effective technique in the management of metaphyseal bone loss of distal femur.

Biomechanical analysis of bridge combined fixation system as a novel treatment for the fixation of type A3 distal femoral fractures

Background

To compare the biomechanical parameters of AO/OTA type A3 distal femoral fractures fixed bilaterally with a bridge combined fixation system (BCFS) and lateral locking compression plate + locking reconstruction plate (LCP + LRP).

Methods

Twelve A3 distal femoral fracture models with medial cortical defects of the distal femur were created using synthetic femoral Sawbones. BCFS and LCP + LRP were used for bilateral fixation, with six in each group. Axial compression and torsion tests were performed on the two groups of fracture models to determine their stiffness during axial compression and the Torsional stiffness during torsion tests. Axial compression failure tests were performed to collect the vertical loads of the ultimate failure tests.

Results

In the test conducted on the fixed type A3 distal femoral fracture models, the axial stiffness in the BCFS group (group A) (1,072.61 ± 113.5 N/mm) was not significantly different from that in the LCP + LRP group (group B) (1,184.13 ± 110.24 N/mm) (t = 1.726, P = 0.115), the Torsional stiffness in group A (3.73 ± 0.12 N.m/deg) was higher than that in group B (3.37 ± 0.04 N.m/deg) (t = 6.825, P < 0.001),and the ultimate failure test of type A3 fracture model showed that the vertical load to destroy group A fixation (5,290.45 ± 109.63 N) was higher than that for group B (3,978.43 ± 17.1 N) (t = 23.28, P < 0.05). Notably, intertrochanteric fractures occurred in groups A and B.

Conclusions

In the fixation of type A3 distal femoral fractures, the anti-axial compression of the BCFS group was similar to that of the LCP + LRP group, but the anti-torsion was better.

[Translated article] Comparative clinical and biomechanical study of different types of osteosynthesis in the treatment of distal femur fractures

INTRODUCTION AND OBJECTIVES

Distal femoral fractures represent a problem due to their high number of complications. The aim was to compare the results, complications and stability achieved with retrograde intramedullary nailing and the angular stable plate in the treatment of distal femoral diaphyseal fractures.

MATERIAL AND METHOD

A clinical and experimental biomechanical study was carried out using finite elements. The results of the simulations allowed us to obtain the main results related to the stability of osteosynthesis. For clinical follow-up data, frequencies were used for qualitative variables, and Fisher's exact test and χ2 test were used to evaluate the significance of the different factors, with the condition of P<.05.

RESULTS

In the biomechanical study, the retrograde intramedullar nails demonstrated superiority, obtaining lower values in terms of global displacement, maximum tension, torsion resistance, and bending resistance. In the clinical study, the rate of consolidation of the plates was lower than nails (77% vs. 96%, P=.02). The factor that most influenced the healing of fractures treated with plate were the central cortical thickness (P=.019). The factor that most influenced the healing of nail-treated fractures was the difference between the diameter of the medullary canal and the nail.

CONCLUSIONS

Our biomechanical study shows that both osteosynthesis provide sufficient stability, but biomechanically behaves differently. Nails provide greater overall stability being preferable the use of long nails adjusted to the diameter of the canal. Plates form less rigid osteosynthesis, with little resistance to bending.

Comparative clinical and biomechanical study of different types of osteosynthesis in the treatment of distal femur fractures

INTRODUCTION AND OBJECTIVES

Distal femoral fractures represent a problem due to their high number of complications. The aim was to compare the results, complications and stability achieved with retrograde intramedullary nailing and the angular stable plate in the treatment of distal femoral diaphyseal fractures.

MATERIAL AND METHOD

A clinical and experimental biomechanical study was carried out using finite elements. The results of the simulations allowed us to obtain the main results related to the stability of osteosynthesis. For clinical follow-up data, frequencies were used for qualitative variables, and Fisher's exact test and χ2 test were used to evaluate the significance of the different factors, with the condition of P<.05.

RESULTS

In the biomechanical study, the retrograde intramedullar nails demonstrated superiority, obtaining lower values in terms of global displacement, maximum tension, torsion resistance, and bending resistance. In the clinical study, the rate of consolidation of the plates was lower than nails (77% vs. 96%, P=.02). The factor that most influenced the healing of fractures treated with plate were the central cortical thickness (P=.019). The factor that most influenced the healing of nail-treated fractures was the difference between the diameter of the medullary canal and the nail.

CONCLUSIONS

Our biomechanical study shows that both osteosynthesis provide sufficient stability, but biomechanically behaves differently. Nails provide greater overall stability being preferable the use of long nails adjusted to the diameter of the canal. Plates form less rigid osteosynthesis, with little resistance to bending.

Dual plating for fixation failure of the distal femur: Finite element analysis and a clinical series

BACKGROUND

The optimal technique for managing distal femur fixation failure remains inconclusive. The author studied the efficacy of a combined proximal humerus locking compression plate (LCP-PH) and 3.5 mm reconstruction plate (LCP-RP) by finite element (FE) analysis and retrospectively described the clinical outcomes of the present technique in such difficult circumstances.

METHODS

Biomechanical study setting included FE models of the distal femur with remaining holes from previous distal femur LCP (LCP-DF) fixation stabilized with three different constructs i.e., LCP-DF alone, LCP-DF-and-LCP-RP, as well as LCP-PH-and-LCP-RP. All settings were analyzed by using FE under physiological loads. Regarding the clinical series, the outcomes of 8 LCP-DF fixation failures operated on by the present technique were retrospectively reviewed.

RESULTS

High Implant stress of 911.2 MPa and elastic strain at fracture site of 200.8 µɛ were found when stabilized with LCP-DF. The constructs of LCP-DF-and-LCP-RP, and LCP-PH-and-LCP-RP presented lower implant stress compared to LCP-DF, 511.5, and 617.5 MPa, respectively. The elastic strain of both dual plating constructs was also 4-5 times lower than LCP-DF and differed from each other by approximately 10 µɛ. Regarding the clinical series, bony consolidation was achieved in all cases with a mean duration of 28.5 weeks (range 24-36). An average ROM of the affected knee was 115° (range 105-140). Regarding the KSS, 1 was determined to be excellent and 7 to be good.

CONCLUSION

By the biomechanical analysis and the clinical results, the construct of LCP-PH-and-LCP-RP could be an effective technique for revision surgery of LCP-DF fixation failure.

Finite element analysis between Hunsuck/Epker and novel modification of Low Z plasty technique of mandibular sagittal split osteotomy

A novel modification of the Low Z plasty (NM-Low Z) technique for bilateral sagittal split osteotomy was recently proposed. The osteotomy line was modified more inferiorly than in the conventional Hunsuck–Epker (HE) approach. The NM-Low Z technique enhances the mandibular setback distance and degree of rotation in severe skeletal discrepancies. This study aimed to investigate the biomechanical behavior under simulated forces, and to compare the NM-Low Z and HE techniques on the mandible with Class III skeletal deformity at 1 week, 3 weeks, and 6 weeks post-operation. Physiological muscular and occlusal loads were simulated using the finite element (FE) method. Stresses on the miniplate, screws, and bone were observed and compared between the two models. The elastic strain at the fracture site was observed for the optimal bone-healing capacity. The NM-Low Z model exhibited a lower stress than the HE model at every stage post-operation. Both models demonstrated elastic strains within the normal range for bone healing. In summary, the biomechanical behavior of the NM-Low Z technique is comparable to that of the conventional EH technique. NM-Low Z could facilitate post-operation skeletal stability by reducing the stress on fixation materials during bone healing.

Modified pin and plate fixation for low intercondylar fractures of the humerus: biomechanical study corroborated with a case series

BACKGROUND

Establishing fracture union of low and comminuted intercondylar fractures of the humerus is inherently challenging. The purposes of the present study were to investigate the biomechanical effectiveness of pin & plate (PP) fixation compared to other dual-plating techniques by finite element analysis, and to present a technical description as well as retrospectively review the outcomes of PP fixation in such difficult fractures.

METHODS

Low-level intercondylar fracture 3D models of the humerus were virtually stabilized with three fixations on lateral side including PP, lateral pre-contoured locking compression plate (L-LCP), and variable angle lateral pre-contoured locking plate (VA-L-LCP) whereas medial pre-contoured locking compression plate (M-LCP) on medial side. Loading conditions under consideration were axial compression, internal rotation, posterior bending, and valgus rotation. Regarding the clinical series, eight patients with intra-articular and comminuted fractures of the distal humerus (6 intercondylar fractures, 1 fracture-subluxation, and 1 isolated lateral condylar fracture) were operated by isolated PP fixation or combinations of PP and the other standard implants. Data were collected on fracture union, perioperative complications, and objective clinical outcomes.

RESULTS

Biomechanical results revealed the most instability of the fracture occurring under posterior bending. PP fixation presented comparable fracture stability and fragment displacement compared to other dual-plating fixations, except stress on the Kirschner wire under internal rotation which was higher than other fixations. Regarding the clinical series, fracture union was achieved in all cases with an average union time of 17 weeks (range 12-20). All except one patient had good-to-excellent MEPS results with an average Disabilities of the Arm, Shoulder, and Hand (DASH) score of 14.6 (range 0-45) and an average arc of elbow motion of 107.5 degrees (range 60-140).

CONCLUSION

By the biomechanical performance, PP fixation is a reliable technique for fixation of low intercondylar fractures of the humerus. Supported by the clinical outcomes, the present technique could be an alternative for this particular fracture especially when severe comminution prevents the use of the standard dual plating technique.

Simplified Mechanical Tests Can Simulate Physiological Mechanics of a Fixation Construct for Periprosthetic Femoral Fractures

Plate fractures after fixation of a Vancouver Type B1 periprosthetic femoral fracture (PFF) are difficult to treat and could lead to severe disability. However, due to the lack of direct measurement of in vivo performance of the PFF fixation construct, it is unknown whether current standard mechanical tests or previous experimental and computational studies have appropriately reproduced the in vivo mechanics of the plate. To provide a basis for the evaluation and development of appropriate mechanical tests for assessment of plate fracture risk, this study applied loads of common activities of daily living (ADLs) to implanted femur finite element (FE) models with PFF fixation constructs with an existing or a healed PFF. Based on FE simulated plate mechanics, the standard four-point-bend test adequately matched the stress state and the resultant bending moment in the plate as compared with femur models with an existing PFF. In addition, the newly developed constrained three-point-bend tests were able to reproduce plate stresses in models with a healed PFF. Furthermore, a combined bending and compression cadaveric test was appropriate for risk assessment including both plate fracture and screw loosening after the complete healing of PFF. The result of this study provides the means for combined experimental and computational preclinical evaluation of PFF fixation constructs.

Biomechanical performance of short and long cephalomedullary nail constructs for stabilizing different levels of subtrochanteric fracture

INTRODUCTION

The aim of this study was to assess biomechanical performance of short and long Cephalomedullary nail constructs consisting of different number of distal screw for stabilizing different levels of subtrochanteric fracture.

MATERIALS AND METHODS

The femur obtained from computed tomography scanner was used to create a transverse fracture at 15 mm (level A), 35 mm (level B), and 55 mm (level C) below the lesser trochanter. Short and long Cephalomedullary nails were virtually inserted to the fractured femur. Four-node tetrahedral element was used to build up finite element (FE) models for biomechanical analysis. The analysis focused on post-operative stage of partial weight-bearing.

RESULTS

Stress on the implant localized at the surface between lag screw/nail and distal screw/nail. Short Cephalomedullary nail exhibited higher stress than long Cephalomedullary nail. The stress in short Cephalomedullary nail could be reduced by using two distal screws fixation and the fracture at level A produced less stress than that of level B and C. Either short or long nail with two distal screws is sufficient to withstand the stress magnitude produced from the physiologic load. When single dynamic distal screw was used, stress on implant, elastic strain at fracture gap, and bone stress reached the high values. Elastic strain of the fracture gap at level C were less than that of level A and B, but no statistically significant difference. There was no proximal cancellous bone damage observed from the FE analysis.

CONCLUSIONS

Long Cephalomedullary nail with at least two distal locking screws remains a proper implant for subtrochanteric fracture fixation in overall locations. However, short Cephalomedullary nail with two distal screws may be a candidate for a high subtrochanteric fracture. Single dynamic screw insertion is strongly not recommended with either short or long nail regarding implant failure.

A systematic review of the use of titanium versus stainless steel implants for fracture fixation

Background:

Controversy exists regarding the use of titanium and stainless steel implants in fracture surgery. To our knowledge, no recent, comprehensive review on this topic has been reported.

Purpose:

To perform a systematic review of the evidence in the current literature comparing differences between titanium and stainless steel implants for fracture fixation.

Methods:

A systematic review of original research articles was performed through the PubMed database using PRISMA guidelines. Inclusion criteria were English-language studies comparing titanium and stainless steel implants in orthopaedic surgery, and outcome data were extracted.

Results:

The search returned 938 studies, with 37 studies meeting our criteria. There were 12 clinical research articles performed using human subjects, 11 animal studies, and 14 biomechanical studies. Clinical studies of the distal femur showed the stainless steel cohorts had significantly decreased callus formation and an increased odds radio (OR 6.3, 2.7-15.1; P < .001) of nonunion when compared with the titanium plate cohorts. In the distal radius, 3 clinical trials showed no implant failures in either group, and no difference in incidence of plate removal, or functional outcome. Three clinical studies showed a slightly increased odds ratio of locking screw breakage with stainless steel intramedullary nails compared with titanium intramedullary nails (OR 1.52, CI 1.1-2.13).

Conclusion:

Stainless steel implants have equal or superior biomechanical properties when compared with titanium implants. However, there is clinical evidence that titanium plates have a lower rate of failure and fewer complications than similar stainless steel implants in some situations. Although our review supports the use of titanium implants in these clinical scenarios, we emphasize that further prospective, comparative clinical studies are required before the conclusions can be made.

Biomechanical behavior of retrograde intramedullary nails in distal femoral fractures

Fractures of the distal femur affect three different groups of individuals: younger people suffering high-energy trauma, elderly people with fragile bones and people with periprosthetic fractures around previous total knee arthroplasty. Main indications of intramedullary nailing are for supracondylar fractures type A or type C of the AO classification. The main objective of the present work is to analyze, by means of FE simulation, the influence of retrograde nail length, considering different blocking configurations and fracture gaps, on the biomechanical behavior of supracondylar fractures of A type. A three dimensional (3D) finite element model of the femur from 55-year-old male donor was developed, and then a stability analysis was performed for the fixation provided by the retrograde nail at a distal fracture with different fracture gaps: 0.5 mm, 3 mm y 20 mm, respectively. Besides, for each gap, three nail lengths were studied with a general extent (320 mm, 280 mm and 240 mm), considering two transversal screws (M/L) at the distal part and different screw combinations above the fracture. The study was focused on the immediately post-operative stage, without any biological healing process. In view of the obtained results, it has been demonstrated new possibilities of blocking configuration in addition to the usual ones, which allows establishing recommendations for nail design and clinical practice, avoiding excessive stress concentrations both in screws, with the problem of rupture and loss of blocking, and in the contact of nail tip with cortical bone, with the problem of a new stress fracture.

Application of a double reverse traction repositor in the retrograde intramedullary nailing of distal femur fractures

Objective

The purpose of this prospective study was to introduce the application of a double reverse traction repositor (DRTR) in the retrograde intramedullary nailing (RE-IMN) of AO/OTA 33A distal femur fractures.

Patients and methods

A total of 27 patients with AO/OTA type 33A distal femur fractures who were admitted from January 2015 to May 2017 to a level I trauma center of a tertiary university hospital were enrolled in this prospective study. A DRTR was used to facilitate RE-IMN for the reduction of distal femur fractures in all patients. The demographic and fracture characteristics, surgical data, postoperative complications, and prognostic indicators of 24 patients were recorded.

Results

The DRTR helped achieve and maintain the reduction of all distal femur fractures in the present study. All surgeries were conducted by closed reduction, and excellent alignment was observed in the postoperative X-ray images. In the present study, 18 males and 6 females were included, and the average age of all patients was 51.3 years (range, 24–68 years). The mean operation time, intraoperative blood loss, intraoperative fluoroscopy time, and length of postoperative hospital stay were 137 min (range from 80 to 210 min), 320 ml (range from 200 to 600 ml), 28 (from 24 to 33), and 9 days (from 5 to 14 days), respectively. Eleven patients were found to have postoperative deep venous thrombosis before discharge. No cases of wound infection were observed. No cases of nonunion or malunion were observed. The average follow-up duration was 21 months (18–30 months). The average HHS, LKFS, and VAS scores at the 1-year follow-up were 89.9 (86–97), 79.1 (75–87), and 2.1 (from 0 to 5). No complications associated with DRTR were found.

Conclusions

A DRTR can be successfully applied in the treatment of distal femur fractures with RE-IMN, and it can not only help achieve or maintain the reduction of distal femur fractures with closed methods but also promote fixation with RE-IMN.

Single lag screw and reverse distal femur locking compression plate for concurrent cervicotrochanteric and shaft fractures of the femur: biomechanical study validated with a clinical series

BACKGROUND

The optimal surgical management of concurrent cervicotrochanteric and shaft fractures of the femur has not been consensual. The authors investigated the reliability of combined single lag screw and reverse distal femur locking compression plate (LCP-DF) by finite element (FE) study and retrospectively described the present technique for these dual fractures.

METHOD

Intact femurs were derived from CT data, and the implant models were created by using CAD software. The fractured femur and implant models were virtually aligned based on the surgical techniques before converting to the FE model. In the FE model, applied boundary conditions included body weight, muscle forces, and constraint of the joints. Regarding clinical series, three patients with these dual fractures of the femur and 2 with cervicotrochanteric fractures with subtrochanteric extension were operated on by the proposed technique. The collected data include operative time, postoperative complications, union times, and clinical outcomes.

RESULTS

Equivalent von Mises stress exhibited on dynamic hip screws with an anti-rotational screw was higher than the other techniques, close to the yield stress of the material. Multiple screw fixation produced better stability for transcervical fractures whereas the proposed technique of combined single lag screw and reverse LCP-DF provided better stability for intertrochanteric fractures. No significant difference in cortical bone stress was found between multiple screw construct and the proposed technique. The proposed technique presented a lower risk of secondary fractures, as the strain energy density (SED) in cancellous bone was lower than multiple screw construct. Regarding clinical series, all fractures were united with a mean union time of-16.1 weeks (range 12-20). There were no any postoperative complications. Regarding the Harris score, 1 was determined to be excellent value, and 4 to be good.

CONCLUSION

By the FE results, a combination of a single lag screw and reverse LCP-DF is an effective technique for fixation of cervicotrochanteric fractures. Empowered by the clinical results, this proposed technique could be an alternative for concurrent cervicotrochanteric and shaft fractures of the femur especially when either single-system or dual-system devices seem not to be suitable.

Comparative analysis of the biomechanical behavior of anterograde/retrograde nailing in supracondylar femoral fractures

Supracondylar femoral fractures account for a noticeable percentage of the femoral shaft fractures, affecting two etiological groups: high energy trauma in young men, with good bone quality, and older women with osteoporotic femur. Surgical treatment of those kind of fractures remains controversial, with different surgical options such as plate and sliding barrel locking condylar plate, less invasive stabilization system (LISS) or intramedullary nailing, which has emerged as a new fixation choice in the treatment of that type of fractures. The present work performs a comparative study about the biomechanical behavior of anterograde and retrograde nailing in supracondylar femoral fractures type A, in order to determine the best choice of nailing and locking configuration. A three-dimensional finite element model of the femur was developed, modeling femoral supracondylar fracture and different nailing configurations, both for anterograde and retrograde nails. The study was focused on the immediately post-operative stage, verifying the appropriate stability of the osteosynthesis. The obtained results show a better biomechanical behavior for anterograde nails, providing a better stability from the point of view of global movements, lower stresses in screws, and less stress concentration in cortical bone. So, for the analyzed fractures and osteosyntheses types, anterograde nailing has demonstrated to be a better surgical option, being an excellent indication in supracondylar fractures of femur, with clear benefits compared to retrograde nailing, providing a better stabilization which enables for a more satisfactory fracture healing.

Biomechanical analysis of the stability of anterograde reamed intramedullary nails in femoral spiral fractures

Femoral shaft fractures present high morbidity and important complications and consequences, being spiral fractures the most complicated from a biomechanical point of view, being unstable and without possibility of getting a good contact between nail and femoral endosteum. Femoral diaphyseal fractures are treated, usually, by means of intramedullary nailing. So, it is necessary to know the osteosynthesis stability and which locking screws combination is optimal. This work studies the use of reamed locked intramedullary nails in spiral femoral fractures located along zones 2 and 4 of wiss, depending on the spire length, corresponding to 32-A spiral type in AO/OTA classification, which represent a percentage of 23% within the total of diaphyseal fractures. A three-dimensional finite element model of the femur was developed, modeling a spiral fracture with different spiral lengths and gaps. A femoral nail was used, considering two transversal screws both at the proximal and the distal parts. The study was focused on the immediately post-operative stage, verifying the appropriate stability of the osteosynthesis. Reamed intramedullary blocked nails provide appropriate stability of femoral spiral fractures, considering global mobility of femoral head with respect to femoral condyles, relative displacements between fragments at fracture site, stresses at nail and locking screws, and stresses at cortical bone. The obtained results show that the use of blocked reamed nails in spiral femoral fractures can be considered as an appropriate surgical technique, providing sufficient stability in order to obtain an adequate fracture healing.

3D CAD/reverse engineering technique for assessment of Thai morphology: Proximal femur and acetabulum

PURPOSE

To assess morphological parameters of proximal femur and acetabulum in Thai population with three-dimensional measurement technique, and to analysis of collateral side symmetric, gender difference, and correlation between morphometric parameters.

METHODS

Investigation was performed in 240 femurs. All three-dimensional femur models were acquitted from 64-slice spiral CT scanner. Morphometric parameters under consideration included acetabular diameter, femoral head diameter, shaft isthmus location, intramedullary canal diameter, diaphyseal diameter, femoral head height, femoral neck isthmus, femoral neck length, neck shaft angle, bow angle, and anteversion angle. All parameters were measured based on functions and least-square regression function in CAD software. Obtained measured data were then used for analysis of collateral side symmetric, gender difference, correlation between morphometric parameters, and compared with other populations.

RESULTS

Female had a smaller dimension compared with male in most of the parameters. No significant difference was observed between left and right femurs. High correlation pairs of morphometric parameters included femoral head diameter-acetabular diameter, femoral head diameter-neck isthmus diameter, femoral head diameter-diaphyseal diameter at shaft isthmus level, acetabular diameter-neck isthmus diameter, neck isthmus diameter-diaphyseal diameter at shaft isthmus level, and acetabular diameter-diaphyseal diameter at shaft isthmus level. Some morphometric parameters of Thai are smaller than other Caucasian, and some Asian nation, i.e. femoral head diameter, femoral neck length, and femoral head height.

CONCLUSIONS

This study provides essential morphometric data for various orthopedic implant designs relating to proximal femur region.