vendex has been researched along with Humeral-Fractures* in 16 studies
2 review(s) available for vendex and Humeral-Fractures
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Parallel versus orthogonal plate osteosynthesis of adult distal humerus fractures: a meta-analysis of biomechanical studies.
There are two widely used distal humerus fracture (DHF) fixation methods with either orthogonal or parallel double-plate osteosynthesis. However, biomechanical studies have shown inconsistent results on which technique is more effective. We performed a meta-analysis to compare these two fixation methods for adult DHF fixation.. We searched the literature for entries discussing the biomechanical testing of orthogonal and parallel fixation techniques for DHFs. We then performed a meta-analysis of the following biomechanical outcome measures: axial/sagittal/coronal/torsional stiffness, load to failure, and torque to failure.. Seventeen studies comparing both constructs were included. The parallel configuration exhibited greater mechanical strength with respect to axial stiffness/load to failure, torsional stiffness, and posterior bending load to failure than the orthogonal constructs. Subgroup analysis revealed that parallel constructs also had higher torsional stiffness in supracondylar fractures.. This meta-analysis shows that parallel constructs provide greater axial stiffness, axial strength, and torsional stiffness than orthogonal plate for DHF fixation. A subgroup analysis revealed that parallel constructs had better torsional stiffness in supracondylar fracture fixation.. IA. Topics: Biomechanical Phenomena; Bone Plates; Fracture Fixation, Internal; Humans; Humeral Fractures; Humerus; Torque | 2019 |
Periprosthetic fractures of the humerus.
Periprosthetic humeral fractures present a treatment challenge for the orthopedic surgeon. The overall incidence of fracture is between 0.5% and 3%, with the majority of fractures occurring intraoperatively and involving the humeral diaphysis. Excess torque produced during surgery is usually responsible for intraoperative fractures. Improper canal preparation or prosthetic placement may also increase the chance of sustaining a fracture. Postoperative fractures are most commonly caused by minor trauma, such as a fall. Poor bone quality, female sex, advanced age, and history of rheumatoid arthritis are the risk factors most commonly associated with periprosthetic fractures. All 4 systems used to describe periprosthetic humeral shaft fractures classify fracture patterns according to the anatomic relation of the fracture to the prosthetic stem. Treatment decisions should be made with respect to obtaining fracture stability, initiating early gleno-humeral motion, and restoring shoulder function. Intraoperative fractures and any postoperative fracture resulting in prosthetic instability should be treated with a long-stem prosthesis extending at least 2 to 3 cortical diameters past the fracture site with consideration for rigid plate fixation. Short oblique or transverse postoperative fractures should be managed with early stable fixation. There has been some support for conservative treatment of long oblique or spiral postoperative fractures. Postoperative diaphyseal fractures distal to the stem generally are well maintained with standard fracture management. Topics: Arthroplasty, Replacement; Humans; Humeral Fractures; Prostheses and Implants; Prosthesis Failure; Risk Factors; Shoulder Joint; Torque | 2005 |
1 trial(s) available for vendex and Humeral-Fractures
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Biomechanical evaluation of an expandable nail for the fixation of midshaft fractures.
The objective of this study was to compare the torsional stability of diaphyseal long bone fractures fixed with either a Fixion nail (DiscOTech, Monroe Township, NJ) or a standard locked Zimmer M/DN locked nail (Zimmer, Warsaw, IN).. Two fracture models were used to evaluate the bone-implant constructs. A transverse osteotomy was created in all tibiae, and a spiral fracture was created in all humeri. Paired specimens were randomly assigned to receive either a Fixion or Zimmer M/DN locked nail. Each implanted construct was cyclically loaded in torsion, and construct stiffness for each fracture type and each bone computed from the resulting load-displacement curves.. Performance of the Fixon nail in the tibial transverse model was variable: 2 of 10 implanted constructs failed during testing, and average construct stiffness was significantly greater for the Zimmer nail. No significant difference was found between the stiffness of the Zimmer M/DN and Fixion implanted humeral constructs either with or without the interlock.. Fracture type significantly affected the performance of the Fixion nail. Our results suggest that the Fixion nail is most suitable for use in fractures where torsional loads across the fracture site are shared between the nail and the bony ends of the fracture, as in a spiral fracture. Topics: Biomechanical Phenomena; Bone Nails; Equipment Design; Fracture Fixation, Intramedullary; Humans; Humeral Fractures; Rotation; Tibial Fractures; Torque; Torsion Abnormality | 2007 |
13 other study(ies) available for vendex and Humeral-Fractures
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Influence of interlocking thread screws to repair simulated adult canine humeral condylar fractures.
To determine the influence of interlocking screw threads on the biomechanical properties of repaired canine humeral condylar fractures.. Ex vivo biomechanical study.. Thirty-six humeral condyles.. Simulated fractures of the lateral aspect of the humeral condyle were stabilized by a 3.5 mm interlocking thread screw (ITS) or 3.5 mm buttress thread screw placed in lag (BTS-L) or positional fashion (BTS-P) and axially loaded at a walk, trot, 2-mm displacement, and failure cycles. Compact flute drill bits (CFBs) were used for ITS constructs and standard flute drill bits (SFB) for BTS constructs. The effects of bit type on drilling parameters and screw type on screw insertion properties and fragment stability were assessed.. CFB produced a 6°C greater temperature increase (p = .042) and required 20 N higher torque (p = .003) than SFB. Insertional torque was greater for ITS than BTS-P (p = .001) and BTS-L (p = .001). Condylar fragment rotation at failure was lower in ITS (lsmean ± SE, 8.3° ± 1.9°) than BTS-L constructs (14.5° ± 2.3°, p = .011). ITS resisted greater loads (1503 ± 105 N) than BTS-P (1189 ± 99 N, p = .038) but not BTS-L (1249 ± 123 N, p = .121) constructs.. Biomechanical performance of constructs was improved with ITS rather than BTS fixation.. ITS can be considered for stabilization of humeral condylar fractures in adult dogs. Topics: Animals; Biomechanical Phenomena; Bone Screws; Dog Diseases; Dogs; Fracture Fixation, Internal; Humeral Fractures; Humerus; Torque | 2021 |
Sagittal plane alignment affects the strength of pin fixation in supracondylar humerus fractures.
Closed reduction with percutaneous pin fixation is commonly used to treat pediatric supracondylar humerus fractures. Various pin configurations of varying biomechanical strength have been described. However, to our knowledge, no biomechanical study has focused on pin alignment in the sagittal plane. Our goal was to compare the stability of fixation using 3 different pin constructs: 3 lateral pins diverging in the coronal plane but parallel in the sagittal plane (3LDP), 3 lateral pins diverging in the coronal and sagittal planes (3LDD), and 2 crossed pins (1 medial and 1 lateral).Transverse fractures were made through the olecranon fossa of 48 synthetic humeri, which were then reduced and pinned in the 3LDP, 3LDD, and crossed-pin configurations (16 specimens per group) using 1.6-mm Kirschner wires. The sagittal plane pin spread was significantly greater in the 3LDD group than in the 3LDP group, whereas we found no difference in the coronal plane. Sagittal extension testing was performed from 0° to 20° at 1°/s for 10 cycles using a mechanical torque stand. The torque required to extend the distal fragment 20° from neutral was compared between groups using one-way analysis of variance with multiple comparison post-hoc analysis. P values ≤.05 were considered significant.The 3LDD configuration was more stable than the 3LDP and crossed-pin configurations. The mean torque required to displace the pinned fractures was 5.7 Nm in the 3LDD group versus 4.1 Nm in the 3LDP group and 3.7 Nm in the crossed-pin group (both, P < .01). We found no difference in stability between the 3LDP and crossed-pin groups (P = .45).In a synthetic biomechanical model of supracondylar humerus fracture, sagittal alignment influenced pin construct stability, and greater pin spread in the sagittal plane increased construct stability when using 3 lateral pins. The lateral pin configurations were superior in stability to the crossed-pin configuration.Level of Evidence: Level V. Topics: Adult; Biomechanical Phenomena; Bone Nails; Bone Wires; Child; Closed Fracture Reduction; Fracture Fixation, Internal; Humans; Humeral Fractures; Iatrogenic Disease; Models, Anatomic; Torque; Ulnar Nerve | 2021 |
A novel adjustable locking plate (ALP) for segmental bone fracture treatment.
A novel Ti6Al4V adjustable locking plate (ALP) is designed to provide enhanced bone stability for segmental bone fractures and to allow precise positioning of disconnected segments. The design incorporates an adjustable rack and pinion mechanism to perform compression, distraction and segment transfer during plate fixation surgery. The aim of this study is to introduce the advantages of the added feature and computationally characterize the biomechanical performance of the proposed design. Structural strength of the novel plate is analyzed using numerical methods for 4-point bending and fatigue properties, following ASTM standards. An additional mechanical failure finite element test is also conducted on the rack and pinion to reveal how much torque can be safely applied to the mechanism by the surgeon. Simulation results predict that the new design is sufficiently strong to not fail under regular anatomical loading scenarios with close bending strength and fatigue life properties to clinically used locking compression plates. The novel ALP design is expected to be a good candidate for addressing problems regarding fixation of multi-fragmentary bone fractures. Topics: Alloys; Biomechanical Phenomena; Bone Plates; Bone Screws; Compressive Strength; Computer Simulation; Equipment Design; Finite Element Analysis; Fracture Fixation, Intramedullary; Humans; Humeral Fractures; Materials Testing; Titanium; Torque | 2019 |
Biomechanical Assessment of Torsional Stiffness in a Supracondylar Humerus Fracture Model.
We assessed the effect on the torsional stability by different pin diameters and varied pin configurations in a biomechanical supracondylar humerus fracture model.. After scanning a model of a pediatric humerus, the image was imported into software. Variable pin trajectories were planned. Acrylonitrile butadiene styrene plastic models were 3-dimensionally printed with predetermined pin trajectories. Models were osteotomized and potted with a polyurethane resin. Five-pin configurations were designed to test coronal and sagittal patterns of pin placement. Each included 3 lateral pins and a medial pin. Pin diameters of 1.6, 2.0, and 2.4 mm were tested in all configurations. Three models for each pin diameter/configuration were tested to ensure uniformity. Stability of the construct was tested to determine the torque needed to deflect the osteotomy 10 degrees in internal/external rotation. Each model was tested 3 times.. In all models/configurations, the 2.4 mm pin diameter was statistically stiffer than 1.6 mm diameter pins; this lost statistical significance in certain patterns when comparing 2.0- and 2.4-mm pins. When comparing a divergent to a parallel configuration in the coronal plane, there was no significant difference in stability when pin diameter or number were controlled. The convergent pin configuration was, in general, the least stable pattern. Use of a medial pin conferred statistically significant stiffness throughout most models as demonstrated with pin deletion. Use of 2 pins was significantly less stiff than most 3-pin models.. Larger pin diameters confer greater stiffness among all patterns. The use of 3 lateral and 1 medial pin was not statistically different than 2 lateral and 1 medial pin in our models. Both patterns were stiffer than 3 lateral pins only or other fewer pin constructs. The alignment of pins in the sagittal plane did not affect overall construct stiffness. Topics: Biomechanical Phenomena; Bone Nails; Child; Fracture Fixation, Internal; Humans; Humeral Fractures; Humerus; Models, Anatomic; Printing, Three-Dimensional; Prosthesis Design; Torque | 2019 |
Subpectoral Biceps Tenodesis With PEEK Interference Screw: A Biomechanical Analysis of Humeral Fracture Risk.
To quantify the torsional load to fracture for subpectoral biceps tenodesis with interference screw fixation.. We randomized 28 specimens from 14 matched-pair full-length humeri (mean age, 55.3 years) into 3 groups: (1) empty ream group (ERG), (2) screw-only group (SOG), and (3) screw-plus-biceps tendon group (SBG). In each group, 1 humerus of each matched pair was prepared according to group allocation and the contralateral humerus remained intact as a control. In the ERG, an 8-mm unicortical hole was reamed 1 cm proximal to the inferior border of the pectoralis major tendon insertion; in the SOG, the humerus was filled with an 8-mm × 12-mm PEEK (polyether ether ketone) screw; and in the SBG, the humerus was filled with a PEEK screw and the cadaveric long head of the biceps tendon. Humeri were tested under torsional displacement at a rate of 1°/s until fracture. Maximum torque, energy to maximum torque, and linear stiffness were used to assess humerus strength.. Compared with contralateral intact specimens, the maximum torque to fracture was reduced by 28% in the ERG (P = .005), 30% in the SOG (P = .014), and 20% in the SBG (P = .046). Energy to maximum torque was similarly reduced in the ERG (P = .007), SOG (P = .023), and SBG (P = .049). Stiffness was increased by 4% in the ERG (P = .498), 9% in the SOG (P = .030), and 4% in the SBG (P = .439).. Drilling an 8-mm unicortical hole in zone 3 of the bicipital tunnel for open subpectoral biceps tenodesis reduces the torsional load to humeral fracture up to 28% at time 0. The addition of a PEEK tenodesis screw alone reduced the maximum torque by 30%, and the addition of a screw with the long head of the biceps tendon reduced the maximum torque by 20%. The total load to fracture was reduced in all settings. Stiffness was not significantly different for the ERG and SBG, but stiffness was significantly higher for the SOG compared with the intact matched humeri at time 0.. When performing a biceps tenodesis, humeral fracture susceptibility is increased with an applied torsional load at time 0. Thus providers must be aware of this reduced integrity when a subpectoral biceps tenodesis is used. Topics: Adult; Aged; Benzophenones; Biomechanical Phenomena; Bone Screws; Cadaver; Female; Humans; Humeral Fractures; Humerus; Ketones; Materials Testing; Middle Aged; Muscle, Skeletal; Polyethylene Glycols; Polymers; Random Allocation; Risk Assessment; Shoulder Joint; Tendons; Tenodesis; Torque | 2018 |
Parallel Plating of Simulated Distal Humerus Fractures Demonstrates Increased Stiffness Relative to Orthogonal Plating With a Distal Humerus Locking Plate System.
This study compared the stiffness of precontoured parallel and orthogonal locking plate configurations in cyclic torsion and bending, and then extension to failure.. Tests were conducted on 9 matched pairs of cadaveric humeri. A 10 mm block of bone was excised from the distal humerus metaphysis to simulate comminution, and fractures were repaired in matched fashion using parallel or orthogonal Biomet ALPS distal humerus locking plates (Biomet, Inc, Warsaw, IN). Specimens were tested at 0.5 degree per second up to ±2 N-m in internal and external rotation for 20 cycles, then in flexion and extension cantilevered bending at 1 mm/s to ±50 N, followed by bending at 1 mm/s to failure in extension.. Torsional stiffness of the parallel configuration group was greater than the orthogonal configuration in both internal and external rotation (P < 0.0001). Also, stiffness in bending was significantly greater in the parallel configuration group in both flexion and extension (P < 0.0001). In extension to failure testing, the parallel plate construct stiffness was significantly greater than the orthogonal configuration (P < 0.005).. The parallel plate configuration demonstrated significantly greater stiffness than the orthogonal plate configuration in torsion and bending using locked distal humerus plates. This greater stiffness may prove desirable in the postoperative management of patients with comminuted distal humerus fractures, providing a stable anatomic reconstruction of the joint to allow early range of motion. Topics: Absorptiometry, Photon; Aged; Aged, 80 and over; Bone Plates; Bone Screws; Cadaver; Compressive Strength; Elastic Modulus; Equipment Failure Analysis; Female; Fracture Fixation, Internal; Humans; Humeral Fractures; Male; Prosthesis Design; Reproducibility of Results; Sensitivity and Specificity; Tensile Strength; Torque; Treatment Outcome | 2016 |
Torsional Fracture of the Humerus after Subpectoral Biceps Tenodesis with an Interference Screw: A Biomechanical Cadaveric Study.
Humeral fracture following subpectoral biceps tenodesis has been previously reported; however, there are no published biomechanical studies reporting the resulting torsional strength of the humerus. Our purpose was to determine if there is an increased risk of humerus fracture after subpectoral biceps tenodesis with an interference screw and to determine if screw size is also a factor. We hypothesized that limbs receiving the procedure would have reduced failure torque and rotation under external rotation compared to untreated controls and that the larger screw size would result in inferior mechanical properties compared to the smaller.. Twenty matched pairs of embalmed cadaveric humeri were subjected to subpectoral biceps tenodesis using either a 6.25 or 8.0mm interference screw, with the untreated contralateral limb serving as a control. Each humerus was mechanically tested in torsional external rotation to failure.. Maximum torque and rotation to failure were reduced in the tenodesis group compared to controls; however, there was no difference between screw sizes. When both screw sizes were combined into a single group, paired t-tests also showed similar differences.. Based on our experiment, there is an increased risk for humerus spiral fracture when subjected to torsional external rotation after subpectoral biceps tenodesis with an interference screw compared to an intact humerus; however, there is not a significant difference between a 6.25mm and 8.0mm screw. Surgeons may elect to use alternative fixation methods in patients at high risk (e.g., overhead throwing athletes, etc.) for torsional loads and fracture. Topics: Biomechanical Phenomena; Bone Screws; Cadaver; Humans; Humeral Fractures; Muscle, Skeletal; Tendons; Tenodesis; Tensile Strength; Torque | 2015 |
Locking plates in osteoporosis: a biomechanical cadaveric study of diaphyseal humerus fractures.
To determine whether locking plates offer an advantage in fixation of fractures in osteoporotic humeral bone.. Biomechanical testing of 18 matched pairs of osteoporotic human cadaver humeri plated posteriorly with either all locked or all nonlocked screws. An established protocol was used to test the constructs with torque applied to a peak of ±10 Nm for 1000 cycles at 0.3 Hz or until failure. Eighteen pairs were tested for failure, 11 pairs were tested for cycles survived, and 10 pairs were tested for stiffness.. University biomechanical laboratory.. Percentage surviving testing, mean cycles survived, and stiffness.. We observed catastrophic failure of the constructs in 47% of the samples. Humeri plated with nonlocking plates failed at a higher rate than those with locking plates (67% nonlocking vs 28% locking, n = 18 pairs, P = 0.008). Locking constructs also outperformed nonlocking constructs in mean cycles survived (707 cycles locking, 345 cycles nonlocking, n = 11 pairs, P < 0.05) and stiffness at 10 cycles (0.853 Nm/degree locking vs 0.416 Nm/degree nonlocking, n = 10 pairs, P < 0.001).. Locking plates were shown to provide improved mechanical performance over nonlocking plates in torsional cyclic loading in a osteoporotic cadaveric fracture model. Our results confirm general conclusions of previous work that used a synthetic bone model of osteoporosis, but we found a high rate of catastrophic failure, questioning the validity of the previously published synthetic model of osteoporosis (overdrilling of synthetic bone) for this application. Topics: Aged; Aged, 80 and over; Bone Plates; Bone Screws; Cadaver; Equipment Design; Equipment Failure; Equipment Failure Analysis; Female; Fracture Fixation, Internal; Humans; Humeral Fractures; Male; Middle Aged; Osteoporotic Fractures; Tensile Strength; Torque; Treatment Outcome | 2012 |
The biomechanical effect of torsion on humeral shaft repair techniques for completed pathological fractures.
In the presence of a tumor defect, completed humeral shaft fractures continue to be a major surgical challenge since there is no "gold standard" treatment. This is due, in part, to the fact that only one prior biomechanical study exists on the matter, but which only compared 2 repair methods. The current authors measured the humeral torsional performance of 5 fixation constructs for completed pathological fractures. In 40 artificial humeri, a 2-cm hemi-cylindrical cortical defect with a transverse fracture was created in the lateral cortex. Specimens were divided into 5 different constructs and tested in torsion. Construct A was a broad 10-hole 4.5-mm dynamic compression plate (DCP). Construct B was the same as A except that the screw holes and the tumor defect were filled with bone cement and the screws were inserted into soft cement. Construct C was the same as A except that the canal and tumor defect were filled with bone cement and the screws were inserted into dry cement. Construct D was a locked intramedullary nail inserted in the antegrade direction. Construct E was the same as D except that bone cement filled the defect. For torsional stiffness, construct C (4.45 ± 0.20 Nm/deg) was not different than B or E (p > 0.16), but was higher than A and D (p < 0.001). For failure torque, construct C achieved a higher failure torque (69.65 ± 5.35 Nm) than other groups (p < 0.001). For the failure angle, there were no differences between plating constructs A to C (p ≥ 0.11), except for B versus C (p < 0.05), or between nailing groups D versus E (p = 0.97), however, all plating groups had smaller failure angles than both nailing groups (p < 0.05). For failure energy, construct C (17.97 ± 3.59 J) had a higher value than other groups (p < 0.005), except for A (p = 0.057). Torsional failure always occurred in the bone in the classic "spiral" pattern. Construct C provided the highest torsional stability for a completed pathological humeral shaft fracture. Topics: Adult; Biomechanical Phenomena; Bone Neoplasms; Humans; Humeral Fractures; Humerus; Materials Testing; Mechanical Phenomena; Stress, Mechanical; Torque | 2012 |
Biomechanical analysis of lateral humeral condyle fracture pinning.
The purpose of this study was to determine the optimum pin configuration and the number of pins needed to stabilize the Milch type II lateral humeral condyle fractures in a pediatric bone model.. Forty synthetic pediatric humeri were sectioned through the lateral distal humerus to simulate a Milch type II lateral condyle fracture. Each fracture was stabilized with 0.062-in K-wires in 1 of 5 configurations: 2 convergent pins, 2 parallel pins, 2 divergent 30-degree pins, 2 divergent 60-degree pins, and 3 divergent pins (n=8/group). Models were tested in extension, flexion, varus, and valgus by applying a translational force through the distal fragment at 0.5 mm/sec oscillating between 5 N and 50 N for 10 cycles. For internal and external rotation, constructs were tested at 0.5 degree/sec between ±1 Nm more than 10 cycles. The maximum force and torque values were also recorded. For bending loads, stiffness was calculated between 0.5 and 5 mm of displacement, whereas torsional stiffness was calculated between 1 degree and 10 degrees of rotation. Data for stiffness were analyzed with a 1-way analysis of variance and a 2-sample t test (P<0.05).. Among 2-pin configurations, divergent (60 degrees) pins provided statistically greater stability than less divergent pins in torsional loading, and greater stability than parallel pins in valgus loading. Three divergent pins had statistically greater stability than all the 2-pin configurations in valgus and torsional loading, and tended to provide more secure fixation in varus loading.. For 2-pin constructs, maximizing pin divergence at the fracture site provided greater stability in torsional loading and valgus loading. The addition of a third pin in a divergent orientation increases stability compared with 2-pin constructs in valgus, internal, and external rotation loading.. Bicortical pins placed with maximum divergence and spread at the fracture site maximizes stability for 2-pin constructs in Milch type II lateral condyle fractures. If the stability of the fracture is questionable after 2 pins are inserted, the addition of a divergent third pin enhances the stability. Topics: Biomechanical Phenomena; Bone Nails; Bone Wires; Child; Fracture Fixation; Humans; Humeral Fractures; Models, Anatomic; Rotation; Torque | 2011 |
Is humeral segmental defect replacement device a stronger construct than locked IM nailing?
Intramedullary (IM) nailing is currently the most common method for treating patients with impending pathologic humeral fractures; however, this treatment is associated with known complications primarily owing to violation of the rotator cuff during insertion. A better option is needed. To determine if a humeral segmental replacement prosthesis would provide a stronger construct compared with an IM nail in this setting, we compared the mechanical properties of these two devices in a cadaver model simulating an impending pathologic fracture. In each of nine matched pairs of fresh human humeri one was randomly selected to undergo a 50% lateral middiaphyseal defect simulating an impending pathologic fracture and subsequent fixation with an IM nail and bone cement. The contralateral humerus underwent fixation using a humeral segmental defect prosthesis. We determined T-scores using DEXA. Each specimen subsequently was tested in torsion to failure. Peak torque and peak rotation at failure were greater for the prosthesis specimens whereas torsional stiffness was greater for the IM nail specimens. We found a linear relationship between peak torque and T-score for each device with the slopes of the lines suggesting the construct with the prosthesis can withstand greater forces than the IM nail and the differences between devices were greater in weaker bones. Topics: Absorptiometry, Photon; Biomechanical Phenomena; Bone Nails; Cementation; Compressive Strength; Equipment Failure Analysis; Humans; Humeral Fractures; Humerus; Internal Fixators; Postoperative Complications; Prosthesis Failure; Prosthesis Implantation; Torque | 2010 |
Computer simulation of humeral shaft fracture in throwing.
Throwing fractures of the humerus are well known, but the exact mechanism of injury is not clear. It has been postulated that these may be stress fractures because the forces have not seemed sufficient to cause acute fractures while throwing.. Using finite element analysis, we reproduced fractures of the humerus using 3-dimensional models built from computed tomography images of 5 healthy volunteers. To apply the load during throwing, we assumed that the humeral head was completely fixed, and external rotation torque was applied to the distal end of the humerus until the stress of the bone elements became greater than yield stress. We reproduced the fracture line by removing the bone elements.. The maximum stress concentration was seen in the distal shaft, where a typical spiral fracture was created in all cases. In the humeral models, the torque required to initiate fracture ranged from 51 to 70 Nm. A strong correlation existed between the torque required to initiate fracture and thickness of the humeral cortical bone (R(2) = 0.74).. These results indicate that thickness of the humerus represents one factor contributing to fractures that occur while throwing.. Basic science study. Topics: Athletic Injuries; Biomechanical Phenomena; Computer Simulation; Finite Element Analysis; Humans; Humeral Fractures; Male; Stress, Mechanical; Tensile Strength; Tomography, X-Ray Computed; Torque; Young Adult | 2010 |
[Internal fixation of proximal humerus fractures].
Intramedullary nails and angle-fixed plates have recently been used in proximal humerus fractures. Rigid implants might be associated with an increased risk of failure in osteoporotic conditions.. Unstable fractures of the surgical neck were created in 24 pairs of human humeri. The biomechanical properties of four implants were analysed. These were a nail with conventional interlocking (PHN-K), a nail with spiral blade interlocking (PHN-S), the T-plate, and an internal fixator with elastic screw properties (reference). The specimens were subjected to axial loading and torque. Stiffness, plastic deformity, and load to failure were assessed.. The PHN-S was stiffer than the internal fixator. The PHN-K and T-plate were stiffer only during torque. Less subsidence was observed for the PHN-S. This implant failed at higher loads than the other implants.. The PHN-S offers biomechanical advantages in unstable fractures of the surgical neck of the humerus. Elastic implant properties, however, are disadvantageous. Topics: Aged; Biomechanical Phenomena; Bone Nails; Bone Plates; Data Interpretation, Statistical; Female; Fracture Fixation, Internal; Fracture Fixation, Intramedullary; Fracture Healing; Humans; Humeral Fractures; Internal Fixators; Radiography; Torque | 2005 |