Human Cadaveric Femora Research Articles

Is the buccal compartment a masticatory space extension or an anatomic space in itself? Evidence based on medical images and human cadaver dissection.

According to some authors, the buccal space is incompletely closed with no real anatomical separation from the masticator space, and also has no fascial limit toward the cranial and caudal regions. However, several other authors consider this anatomic area to be a separated space. The goal of this study was to provide a detailed description of the normal anatomy using medical images and human cadaveric head material dissection of this facial anatomic region, to precisely clarify its condition as an extension of the masticator space or an independent space. The buccomasseteric area in 25 male and female patients aged 14-68years, who were referred for various head and neck disorders that did not compromise the masticatory and buccal area, was analyzed by magnetic resonance imaging on the axial and coronal planes. The region was further examined by dissection of the buccomasseteric area in four heads of fresh adult male and female human cadavers aged 30-65years. The findings demonstrated that the buccal compartment should be considered part of the masticator space, rather than a space in itself. This was mainly because a corridor was positioned medially to the tendon of the masseter muscle that communicated the infratemporal region of the masticator space with the buccal region, with no fascial barrier at this level that could separate it from the masticator space. The present study suggests that the buccal compartment is part of the masticator space, rather than a space in itself.

Knee stiffness and viscosity: New implementation and perspectives in prosthesis development.

The pendulum test is a method applied to measure passive resistance of the knee. A new and simple pendulum test with instrumentation based on infrared camera was used to evaluate knee stiffness and viscosity on a female human cadaver. The stiffness and viscosity were calculated based on the kinetic data. During the measurements, the periarticular and intraarticular soft tissue of the knee was gradually removed to determine the stiffness and viscosity as a function of the tissue removal rate. The measurements showed that the removal of tissue around the joint reduces the damping of leg oscillation, and therefore decreases the stiffness and viscosity. The contribution to knee joint damping was 10% for the skin, 20% for ligaments, and 40% for muscles and tendons. Tissue removal has a very large impact on the knee stiffness and viscosity.

THE EFFECT OF COMPUTED TOMOGRAPHY CURRENT REDUCTION ON PROXIMAL FEMUR SUBJECT-SPECIFIC FINITE ELEMENT MODELS

Many studies have addressed the modulation of computed tomography (CT) parameters, and particularly of tube current, to obtain a good compromise between the X-ray dose to the patient and the image quality for diagnostic applications. This study aimed at evaluating the influence of dose reduction by means of tube current reduction on the CT-based subject-specific finite element (FE) modeling. To this aim, CT scans at stepwise reduced values of tube current from 180[Formula: see text]mAs to 80[Formula: see text]mAs were performed on: (i) a densitometric phantom, to quantify the changes in the calibration equation; (ii) a fresh-frozen, water submersed, human cadaver femur, to quantify changes in geometry reconstruction and material mapping from CT, as well as strain prediction accuracy, based on the in vitro strain measurements available; (iii) a fresh-frozen human cadaver thigh with soft tissues attached, to quantify FE results changes in conditions similar to those found in vivo. The results showed that the tube current reduction does not affect the 3D modeling and the femur FE analysis. Our pilot study highlights the possibility of performing CT scans with reduced dose to generate biomechanical models, although a confirmation by performing larger studies with clinical CT data is needed.

Significant differences in femoral torsion values depending on the CT measurement technique.

IntroductionThis study compared the feasibility of six different CT-based measurement techniques for establishing an indication for derotational osteotomy in the cases of patellar instability or femoral fracture.Materials and methodsCT scans of 52 single human cadaver femora were measured using six different torsion measurement techniques (described by Waidelich, Murphy, and Yoshioka on transverse images and Hernandez, Jarrett, and Yoshioka on oblique images). All measurements were performed by four observers twice to assess intraobserver and interobserver agreement. The intraclass correlation coefficient (ICC), ANOVA, and Bonferroni post hoc test were used for the statistical analysis.ResultsSignificant differences (P < 0.001) between the values for femoral torsion were observed with all techniques except Yoshioka’s techniques on transverse and oblique slices (P = 1.000) (transverse images: Waidelich 22.4° ± 6.8°, Murphy 17.5° ± 7.0°, Yoshioka 13.4° ± 6.9°; oblique images: Hernandez 11.4° ± 7.4°, Jarrett 14.9° ± 7.5°, Yoshioka oblique 13.4° ± 7.1°). Intraobserver and interobserver agreement showed a high level of reproducibility (ICC 0.877–0.986; mean 0.8°–2.9°) for all techniques, with the greatest difference being observed with Hernandez’s technique (11.4°/10°).ConclusionsFemoral torsion values depend on the measurement technique. When derotational osteotomy is being considered, it is essential to use different threshold values depending on the measurement technique.

Proximity of uterosacral ligament suspension sutures and S3 sacral nerve to pelvic landmarks.

To describe the relationships between pelvic bony landmarks to points along the third sacral nerve and to uterosacral ligament suspension sutures. Three transvaginal uterosacral ligament suspension sutures were placed bilaterally in unembalmed female human cadavers. The third sacral nerve was marked at the foramen (S3a) and at two additional points at 1-cm intervals along its course caudally (S3b, S3c). Three bony pelvic landmarks were identified and marked, including the ischial spine, pubic symphysis, and coccyx. Distances from each landmark to each suture and nerve point were measured. The distance from each landmark to each S3 nerve point was extended radially, encompassing an arbitrary zone in which sutures may be placed and thus where nerve injury may occur. Zones of potential nerve injury included: zone A (closest to the sacral nerve root), zone B, and zone C (closest to the landmark). Descriptive statistics were used and comparisons were made using Student's t test and ANOVA. Ten cadaver specimens were dissected. For the ischial spine, the distances to points S3a, S3b, and S3c were 6.3, 5.4, and 4.6cm respectively. Approximately two thirds of the sutures were noted beyond zone C, indicating a potentially increased risk of nerve injury with suture placement in zones farthest from the ischial spine given their proximity to the sacral nerve. Using the ischial spine as a landmark, increased sacral nerve injury could result from suture placement beyond the mean distance of 4.6cm from the ischial spine. The use of bony landmarks in avoiding sacral nerve injury may be as important as suture depth and angle of suture placement.

Biomechanical determination of the relationship between femoral neck lesion size and the risk of pathological fracture.

Half of the pathological fractures of the proximal femur occur in the neck region. We evaluate the relationship between the defect size within the femoral neck and the risk of pathological fracture. After creating metastasis-like lesions in the neck regions of 21 human cadaver femurs, compression was applied to simulate single-limp stance type loading. First, a loading of 600 Newtons (N) was applied to the 35%-defected femoral necks. If the bone fracture did not occur, the defect size was increased to 45% and the 600 N force was applied again. If no fracture was observed then the defect size was increased to 55% and the bones were loaded again. The 55%-defected bones with no fractures were loaded until a fracture was detected. There were no fractures with the 35%- and 45%-defected femurs until 600 N was applied. However, when the defect size was increased to 55%, 3 bones were fractured before reaching 600 N. The fractures occurred at an average of 455 N in the 3 bones. At a compression of 600 N, 18 bones (84%) were intact, and the loading was continued. 18 femurs with 55%-defected neck regions had an average endurance of 1270 N compression (range 750-2800 N). This study showed that even very osteoporotic bones with large metastases can withstand high forces of compressive loading.

Deformation pattern and load transfer of an uncemented femoral stem with modular necks. An experimental study in human cadaver femurs

BackgroundModular necks in hip arthroplasty allow variations in neck-shaft angles, neck version and neck lengths and have been introduced to improve accuracy when reconstructing the anatomy and hip joint biomechanics. Periprosthetic bone resorption may be a consequence of stress shielding in the proximal femur after implantation of a femoral stem. The purpose of this study was to investigate the deformation pattern and load transfer of an uncemented femoral stem coupled to different modular necks in human cadaver femurs. MethodsA cementless femoral stem was implanted in twelve human cadaver femurs and tested in a hip simulator corresponding to single leg stance and stair climbing activity with patient-specific loading. The stems were tested with four different modular necks; long, short, retro and varus. The long neck was used as reference in statistical comparisons, as it can be considered the “standard” neck. The deformation of bone during loading was measured by strain gauge rosettes at three levels of the proximal femur on the medial, lateral and anterior side. FindingsThe cortical strains were overall reduced on the medial and lateral side of femur, for all implants tested, and in both loading conditions compared to the unoperated femur. Although there were statistical significant differences between the necks, the results did not show a consistent pattern considering which neck retained or lost most strain. In general the differences were small, with the highest significant difference between the necks of 3.23 percentage points. InterpretationThe small differences of strain between the modular necks tested in this study are not expected to influence bone remodeling in the proximal femur.

Histological verification of the prehypogastric and ovarian ganglia confirms a bilaterally symmetrical organization of the ganglia comprising the aortic plexus in female human cadavers.

The aortic plexus is a network of sympathetic nerves positioned along the infrarenal abdominal aorta. Recently, we characterized the aortic plexus and its ganglia (inferior mesenteric, left/right spermatic, and prehypogastric ganglion) in males; however, the literature minimally describes its anatomy in females. In the present study, we conducted the first histological examination of the left and right ovarian ganglia, while also investigating whether females, like males, exhibit a prehypogastric ganglion. The ganglia were dissected from embalmed (n=32) and fresh (n=1) human cadavers, and H&E staining was used to confirm the presence of a left ovarian ganglion in 31/31 specimens, a right ovarian ganglion in 29/29 specimens and a prehypogastric ganglion in 25/28 specimens. Comparable to the topographic arrangement in males, there is a bilateral organization of the ganglia comprising the aortic plexus in females. More specifically, the left and right ovarian ganglia were positioned in close relation to their respective ovarian artery, whereas the prehypogastric ganglion was positioned within the right cord of the aortic plexus, contralateral to the inferior mesenteric ganglion. Using immunohistochemistry, it was shown that all ganglia from the fresh cadaver stained positive for tyrosine hydroxylase, thereby confirming their sympathetic nature. Having provided the first topographical and histological characterization of the ovarian and prehypogastric ganglia in females, future studies should seek to determine their specific function.

A novel locking screw hip stem to achieve immediate stability in total hip arthroplasty: A biomechanical study

IntroductionAs total hip arthroplasty is now applicable for younger, healthier, and more active patients, bone preservation becomes even more essential, and proximal fixation, resulting in less stress shielding, draws special attention with focus on new strategies and implant designs.Recently, a new type of non-cemented fixation of the femoral component, featured with the locking screw hip (LSH) stem, was developed by Scyon Orthopaedics AG (Au-Waedenswil, Switzerland). The idea to rigidly fix the femoral component of a prosthesis for total hip replacement in this fashion evolved from the very good results achieved with the internal point-contact fixator PC-Fix.The purpose of this study was to investigate the unique characteristics of the LSH-stem and to assess its biomechanical performance in comparison to a conventional cemented prosthesis (Mueller straight stem). Material and MethodsSix paired human cadaveric femora were preserved with the method of Thiel, split in two study groups, implanted with either cemented Mueller straight stem or LSH-stem prostheses and biomechanically tested under progressively increasing axial loading until catastrophic failure. Bone mineral density (BMD) of all femora was evaluated in the femoral head prior to implantation. Axial construct stiffness, failure load and cycles to failure were calculated from the machine data and statistically evaluated at a level of significance p = 0.05. ResultsNo statistically significant difference between the LSH-stem and the Mueller straight stem was found in terms of axial construct stiffness (2031.5 N/mm ± 483.1 N/mm and 2403.6 N/mm ± 705.2 N/mm, p = 0.115), failure load (4958.8 N ± 1094.1 N and 5907.2 N ± 1562.8 N, p = 0.138) and cycles to failure (7917.7 ± 2188.1 and 9814.3 ± 3125.6, p = 0.138). BMD showed no significant difference between the two study groups, p = 0.616. ConclusionThe LSH-stem seems to be stable enough to carry loads experienced during the rehabilitation period of a patient after THR. Its stability, which is similar to that of the Mueller straight stem, may justify the clinical application of the LSH-stem under thorough investigation.

Using 3D digital image correlation to visualise the progress of failure of human proximal femur

An accurate measuring tool is required to measure the full-field displacement of the complex geometry of the human proximal femur when subjected to axial loads. Optical techniques, such as digital image correlation (DIC), have been used extensively in order to measure planar or volumetric displacement. Even though DIC methods are now in frequent use in experimental bone mechanics, this technique has only recently been reported to measure 3D proximal ex-vivo femur displacement fields during loading under axial loads. The innovation of this study is to extend the use of the DIC technique to visualise and track the progress of failure of the proximal femur under limb stance configuration. An experimental protocol has been proposed and validated on eight human cadaveric femurs. The results indicated that failure takes place by shearing in the head–neck region. Furthermore, it was found that this method enables to extract additional information on the fracture profile and its initiation. The obtained information can facilitate the interpretation of the in vitro failure behaviour of human femur under axial loading conditions which will serve the validation of hip models.

Accuracy of Femoral Tunnel Placement in Medial Patellofemoral Ligament Reconstruction

Background: Reconstruction of the medial patellofemoral ligament (MPFL) is an established operative procedure for patients with recurrent episodes of lateral patellar instability. However, recent articles have reported remarkable complication rates, with nonanatomic femoral tunnel positioning in up to 64% of patients. Purpose: To evaluate the sensitivity of femoral tunnel placement using lateral fluoroscopic guidance to minor degrees of deviation from the true-lateral view using established radiographic landmarks. Study Design: Controlled laboratory study. Methods: Six human cadaveric femora were used for this study. A 6-mm radiopaque eyelet was used to mark the native femoral insertion of the MPFL according to previously described radiographic landmarks. Radiographic landmarks were also applied with the femur positioned in 2.5° and 5° of internal and external rotation, respectively, and with the femur in 2.5° and 5° of hip abduction and adduction, respectively. The distance between the center of the 6-mm eyelet to the center of the native femoral MPFL insertion, as established in the true-lateral view, was measured and determined as the degree of shift in each position. Results: Hip adduction, abduction, and internal and external rotations of 2.5° resulted in a shift from the native femoral MPFL insertion point to a more distal (adduction), proximal (abduction), anterior (internal rotation), and posterior location (external rotation) of 2.7 ± 0.7, 2.0 ± 0.7, 2.7 ± 1.1, and 3.0 ± 1.3 mm, respectively (all P < .05). Malpositioning increased to a distance of 5.0 ± 0.7 mm distally, 3.6 ± 1.0 mm proximally, 5.2 ± 0.8 mm anteriorly, and 6.2 ± 0.6 mm posteriorly to the native insertion point when the attachment was marked with 5° of divergence from the true-lateral view (all P < .05). Conclusion: The results of this study indicate the high sensitivity of femoral tunnel placement using lateral fluoroscopic guidance to minor degrees of deviation from the true-lateral view. Clinical Relevance: The study highlights the importance of an exact lateral view when fluoroscopic guidance is used for femoral tunnel positioning in the daily practice of MPFL reconstruction, and a possible explanation for the high incidence of nonanatomic tunnel placement is suggested.

Interposition sleeve as treatment option for interprosthetic fractures of the femur: a biomechanical in vitro assessment.

The number of patients having hip and knee arthroplasties on the ipsilateral leg is going to rise. In this regard, the prevalence of interprosthetic femoral fractures is going to increase further. The treatment of these fractures is difficult and sometimes it is impossible to perform an osteosynthesis because of worse bone quality. The goal of this study was to investigate the use of an interposition sleeve as an alternative treatment option for interprosthetic fractures with major bone loss. Six human cadaveric femurs were instrumented using cemented hip- and knee prosthesis. Interprosthetic fractures were induced during a four-point-bending test and then treated using the interposition sleeve. Afterwards the constructs were tested using the four-point-bending test again. Load-to-failure of the construct before fracturing was significantly higher than after treatment with the interposition sleeve (10681N vs. 5083N; p = 0.002). The failure mechanism of the femurs with the interposition sleeve was plastic deformation of the hip or knee prosthesis. The interposition sleeve did not fail in any specimen. The interposition sleeve is a valuable treatment option for interprosthetic fractures in situations in which osteosynthesis is impossible or insecure due to major bone defects. However, fracture healing should be preferred whenever possible.

STUDY OF PROFUNDA FEMORIS ARTERY OF HUMAN CADAVERS IN RAJKOT CITY, INDIA

Background: The profunda femoris artery is the major branch of the femoral artery. It is at critical place in relation to femoral artery for various interventions. Aim: To study the origin of profunda femoris artery. And to compare the cross sectional area of profunda femoris artery between right and left limbs. Material and methods: In this cross sectional study, 51 human femoral triangles from 26 (18 male and 08 female) human cadavers in P.D.U. Government Medical College, Rajkot were dissected and studied during regular dissection classes. Site of origin of profunda femoris artery was noted in relation to femoral artery. The distance of origin of profunda femoris artery from the midpoint of inguinal point was measured and noted. Circumference of profunda femoris artery at the level of origin was measured. The cross sectional area was calculated. Collected data was analyzed by standard statistical formulas with the help of Microsoft excel 2007 and Epi info TM 7 software. Result: Most common (52.95% cases) site of origin was posterolateral from femoral artery. The mean distance of origin of profunda femoris artery from the midpoint of inguinal ligament was 30.17 mm. There was no significant difference in cross sectional area of right and left profunda femoris artery (at 95% confidence interval) Conclusion: Profunda femoris artery is used for angiography, ultrasonography and cardiac catheterization also. It is the major blood supply of the thigh. Its relations with femoral artery, femoral vein and femoral nerve makes it important structure for clinicians. Variations in origin of profunda femoris artery must be considered to avoid complication like aneurism and faulty passage of the catheter. High origin of profunda femoris artery is more prone to damage while accessing femoral artery.

Value of washers in internal fixation of femoral neck fractures with cancellous screws: a biomechanical evaluation.

The purpose of this study was to evaluate the maximum insertion torque of cancellous bone screws in osteoporotic proximal femurs with and without the use of washers. Eight matched pairs of osteoporotic fresh-frozen human cadaveric femurs (age >70 years, all female) were used. Two screws were inserted in each femur either with or without a washer, and maximum insertion torque was measured using a 50 N·m torque transducer. The testing was performed using a customized device, which allowed the torque transducer to apply a constant axial force and rate of rotation to the screws. In 14 of 16 paired trials, the maximum screw insertion torque was higher when a washer was used. The average maximum torque with a washer was 5.1 N·m compared with 3.1 N·m without a washer (P < 0.01). The addition of washers increased the maximum insertion torque of cancellous screws in the proximal femur by 65% in this study. Washers prevent the screw heads from penetrating the lateral cortex at low insertion torque loads, and thereby provide for an improved purchase of the screws in the femoral head with a higher maximum insertion torque. We advocate for routine washer use and encourage future clinical studies to further understand the correlation between their use and improved outcomes in this patient population.

Statistical consequences of using bone mineral density to pair cadaver femurs in comparative ex vivo hip fracture studies.

ObjectiveIn ex vivo hip fracture studies femoral pairs are split to create two comparable test groups. When more than two groups are required, or if paired femurs cannot be obtained, group allocation according to bone mineral density (BMD) is sometimes performed. In this statistical experiment we explore how this affects experimental results and sample size considerations.MethodsIn a hip fracture experiment, nine pairs of human cadaver femurs were tested in a paired study design. The femurs were then re-matched according to BMD, creating two new test groups. Intra-pair variance and paired correlations in fixation stability were calculated. A hypothetical power analysis was then performed to explore the required sample size for the two types of group allocation. ResultsThe standard deviation (sd) of the mean paired difference in fixation stability increased from 2 mm in donor pairs to 5 mm in BMD-matched pairs. Intra-pair correlation was 0.953 (Pearson’s r) in donor pairs and non-significant at -0.134 (Pearson’s r) in BMD-matched pairs. Required sample size to achieve a statistical power of 0.8 increased from ten pairs using donor pairs to 54 pairs using BMD-matched pairs.ConclusionBMD cannot be used to create comparable test groups unless sample size is increased substantially and paired statistics are no longer valid.Cite this article: Bone Joint Res 2014;3:317–20.

A biomechanical comparison of composite femurs and cadaver femurs used in experiments on operated hip fractures

Fourth generation composite femurs (4GCFs, models #3406 and #3403) simulate femurs of males <80 years with good bone quality. Since most hip fractures occur in old women with fragile bones, concern is raised regarding the use of standard 4GCFs in biomechanical experiments. In this study the stability of hip fracture fixations in 4GCFs was compared to human cadaver femurs (HCFs) selected to represent patients with hip fractures.Ten 4GCFs (Sawbones, Pacific Research Laboratories, Inc., Vashon, WA, USA) were compared to 24 HCFs from seven females and five males >60 years. Proximal femur anthropometric measurements were noted. Strain gauge rosettes were attached and femurs were mounted in a hip simulator applying a combined subject-specific axial load and torque. Baseline measurements of resistance to deformation were recorded. Standardized femoral neck fractures were surgically stabilized before the constructs were subjected to 20,000 load-cycles. An optical motion tracking system measured relative movements.Median (95% CI) head fragment migration was 0.8mm (0.4 to 1.1) in the 4GCF group versus 2.2mm (1.5 to 4.6) in the cadaver group (p=0.001). This difference in fracture stability could not be explained by observed differences in femoral anthropometry or potential overloading of 4GCFs. 4GCFs failed with fracture-patterns different from those observed in cadavers.To conclude, standard 4GCFs provide unrealistically stable bone-implant constructs and fail with fractures not observed in cadavers. Until a validated osteopenic or osteoporotic composite femur model is provided, standard 4GCFs should only be used when representing the biomechanical properties of young healthy femurs.

Magnetic Equipped Wire Device-for Closed Interlocking Intramedullary Femoral Nailing: A Method That Avoids Exposure to Ionizing Radiations

Background: Intramedullary nailing is probably the best procedure for treating the long bone fractures in the lower limb. Such operation is guided by fluoroscopy for the guide-wire insertion like fracture reduction and distal locking. Radiation exposure during interlocked nailing continues a matter of challenge. Objectives: The aim of this experimental study was to design and test the new aiming device for closed intramedullary nailing and to reduce the radiation exposure and the operation time during the procedure. Materials and Methods: A stainless steel femoral intramedullary guide wire equipped with a small magnet on its end was designed; and also an exchange tube that would enter into the bone canal upon the guide wire to maintain the alignment. Besides these mentioned parts, we applied the standard classic interamedullary nailing set. Pin guide was inserted in the femoral intramedullary canal from periformis fossa. Another equipped magnetic guide wire was inserted from distal portal which was created in the lateral epicondyle. Two opposite magnetic poles supposed to find each other in the fracture site. After replacing the guide-wire with guide pine; the alignment would be checked by a C-arm. The study has been designed in 4 phases including moulage phase, animal phase on young cows, and a human cadaveric phase. The last step of the study is under design and it consists of a randomized controlled clinical trial on the elective patients. Results: Outcomes of applying the new system on 15 fiberglass artificial femurs and 20 bovine femurs as well as 10 human cadaveric femurs were successful. Conclusions: We found the magnetic field assistant device to be an accurate, radiation-independent jig for close passing of guide wire after close reduction of femoral fracture. It can reduce the need for radiation during placement of guide wire for closed intramedullary nailing of the long bones. More studies are required to improve and evaluate the technique and equipment.

Assessment of Intraosseous Femoral Head Pressures During Cement Augmentation of the Perforated Proximal Femur Nail Antirotation Blade

The benefits of cement augmentation with fixation of osteoporotic pertrochanteric fractures have been previously demonstrated. The objective of this study was 3-fold: (1) To quantify the intraosseous pressure produced during cement augmentation of the perforated proximal femoral nail antirotation (PFNA) blades; (2) To assess whether the pressure generated is influenced by the injection rate; and (3) To assess the amount of force applied during the injection. Six pairs of human cadaveric femurs were used in the study. A basicervical osteotomy was performed, and the heads were instrumented with the PFNA blade. Each pair was randomly assigned into 1 of 2 groups: slow versus rapid injection with polymethylmethacrylate (PMMA) cement. In the slow group, the augmentation was performed using 6 consecutive 1 mL injections, each over 10 seconds. In the rapid group, each 1 mL injection was performed over 5 seconds. For intraosseous pressure measurements, transmitters were inserted to a depth of 5 mm at both the superior and inferior apices of the head. The reaction forces on the syringe were measured as well. There were no significant differences between the slow and rapid injection rates with respect to the peak pressures measured at the 6 time points immediately after cement injection. In both groups, elevations in pressure were transient and returned to baseline values within 30 seconds. The highest pressure recorded in the slow group was 37.3 and 30.7 mm Hg in the rapid group. The force required after each sequential injection increased in both groups; however, significantly higher forces were required to inject cement over 5 than 10 seconds (P = 0.036). This in vitro model is the first one to demonstrate that femoral head cement augmentation is associated with a small transient increase in intraosseous pressure with sequential fast and slow 1 mL injections of up to 6 mL PMMA. We conclude that cement augmentation of the perforated PFNA blade carries a low risk of pressure-induced avascular necrosis.

Feasibility of osteosynthesis of fractured cadaveric hips following preventive elastomer femoroplasty

BackgroundIn vitro cadaveric studies showed that elastomer femoroplasty prevents displacement of fracture parts after proximal hip fracture allowing for conservative treatment. In the event that secondary displacement does occur, the purpose of this present study was to determine the feasibility of performing osteosynthesis of a fractured hip after preventive treatment with elastomer femoroplasty. MethodsTen pairs of human cadaveric femurs were fractured in a simulated fall configuration. From each pair, one femur was randomly selected for elastomer femoroplasty prior to fracture generation and the contralateral femur was used as control. Following hip fracture generation, osteosynthesis was performed in all femurs. The operative time per case, technical difficulties during the procedure, and postoperative energy-to-failure load were recorded. ResultsThe mean (SD) time to perform osteosynthesis was 20 (6) minutes in the control-group and 19 (5) minutes in the elastomer femoroplasty-group (P=0.69). During osteosynthesis of the fractured hip in the elastomer femoroplasty-group, no difficulties including the need for additional instruments to remove elastomer from the proximal femur were recorded. Postoperative energy-to-failure load was similar in the control-group and the elastomer femoroplasty-group. ConclusionFixation with routine osteosynthesis of displaced cadaveric hip fractures is not hindered by the presence of previously injected elastomer.

Malpositioning of the lag screws by 1- or 2-screw nailing systems for pertrochanteric femoral fractures: a biomechanical comparison of gamma 3 and intertan.

The aim of this investigation was to perform a biomechanical comparison between 1- and 2-screw systems used for the treatment of intertrochanteric fractures for centralized and decentralized placement of femoral neck screws of failure loads, stiffness, survival rates, tip apex distance (TAD), and failure mode. As fracture model, an AO 31A2.3 fracture was used. Twelve pairs of human cadaver femora were tested. Femoral neck screws were implanted in the femoral head in center/center, posterior/central, and anterior/superior position in axial/frontal plane. A single-screw system (Gamma 3 Locking Nail; Stryker GmbH & Co. KG) and a 2-screw system (Trigen-Intertan; Smith & Nephew GmbH) were used. To simulate the load in situ, a cyclic load was carried for 10,000 cycles in a material testing machine. If no cyclic failure occurred, femora were loaded until the failure. The systems were compared according to the stiffness, survivability through 10 k cycles, TAD, and load to failure. None of the tested bones failed at center/center location in the decentralized positions 3 Gamma Nail and 2 Intertan specimens failed during cyclic testing. The 2-screw system resisted higher forces in all positions (Gamma: 5370N ± 1924, Intertan: 7650N ± 2043; P = 0.014). Based on these data, it is clear that both the nail systems showed a higher biomechanical stability with a lower TAD. The 2 specimens that failed with the Intertan in the cyclic tests had a TAD ≥49 mm. The cutout failures that we detected during cyclic testing in the Gamma system had a TAD ≥30 mm. Thus, it is clear that the TAD affects failure independent of the implant used. With a less than ideal lag screw placement, however, the Intertan system with 2 integrated screws was able to withstand higher loads in this study.