The success of surgical treatment for fractures hinges on various factors, notably accurate surgical indication. The process of developing and certifying a new osteosynthesis device is a lengthy and ...costly process that requires multiple cycles of review and validation. Current methods, however, often rely on predecessor standards rather than physiological loads in specific anatomical locations. This study aimed to determine actual loads experienced by an osteosynthesis plate, exemplified by a standard locking plate for the femoral shaft, utilizing finite elements analysis (FEA) and to obtain the bending moments for implant development standard tests. A protocol was developed, involving the creation and validation of a fractured femur model fixed with a locking plate, mechanical testing, and FEA. The model’s validation demonstrated exceptional accuracy in predicting deformations, and the FEA revealed peak stresses in the fracture bridging zone. Results of a parametric analysis indicate that larger fracture gaps significantly impact implant mechanical behavior, potentially compromising stability. This study underscores the critical need for realistic physiological conditions in implant evaluations, providing an innovative translational approach to identify internal loads and optimize implant designs. In conclusion, this research contributes to enhancing the understanding of implant performance under physiological conditions, promoting improved designs and evaluations in fracture treatments.
The aim of the study was to analyze the effect of local infiltration analgesia (LIA), peripheral nerve blocks, general and spinal anesthesia on early functional recovery and pain control in primary ...unicompartmental knee arthroplasty (UKA).
Between January 2016 until August 2016, 134 patients underwent primary UKA and were subdivided into four groups according to their concomitant pain and anesthetic procedure with catheter-based techniques of femoral and sciatic nerve block (group GA&FNB, n = 38) or epidural catheter (group SP&EPI, n = 20) in combination with general anesthesia or spinal anesthesia, respectively, and LIA combined with general anesthesia (group GA&LIA, n = 46) or spinal anesthesia (group SP&LIA, n = 30). Outcome parameters focused on the evaluation of pain (NRS scores), mobilization, muscle strength and range of motion up to 7 days postoperatively. The cumulative consumption of (rescue) pain medication was analyzed.
The LIA groups revealed significantly lower (about 50%) mean NRS scores (at rest) compared to the catheter-based groups at the day of surgery. In the early postoperative period, the dose of hydromorphone as rescue pain medication was significantly lower (up to 68%) in patients with SP&EPI compared to all other groups. No significant differences could be detected with regard to grade of mobilization, muscle strength and range of motion. However, there seemed to be a trend towards improved mobilization and muscle strength with general anesthesia and LIA, whereof general anesthesia generally tended to ameliorate mobilization.
Except for a significant lower NRS score at rest in the LIA groups at day of surgery, pain relief was comparable in all groups without clinically relevant differences, while the use of opioids was significantly lower in patients with SP&EPI. A clear clinically relevant benefit for LIA in UKA cannot be stated. However, LIA offers a safe and effective treatment option comparable to the well-established conventional procedures.
The amount of interfragmentary movement has been identified as a crucial factor for successful fracture healing. The aim of our study was to combine finite element analysis with a rigid body ...assumption to efficiently predict interfragmentary movement in fixed tibial fractures. The interfragmentary movement in a transverse tibial shaft fracture (AO/OTA type 42-A3) fixed with a locked plating construct was simulated using finite element analysis. In order to assess the contribution of the components on the resulting interfragmentary movement, the tibia, screws and embedding was either simulated deformable or as rigid body. The rigid and the deformable model accurately predicted the interfragmentary movement (R
2
= 0.99). The axial movement ranged between 0.1 mm and 1.3 mm and shear movements were between 0.2 mm and 0.5 mm. Differences between the two models were smaller than 73
m (axial) and 46
m (shear). The rigid body assumption reduced computation time and memory usage by up to 61% and 97%, respectively.
Postoperative pain control and enhanced mobilization, muscle strength and range of motion following total knee arthroplasty (TKA) are pivotal requisites to optimize rehabilitation and early recovery. ...The aim of the study was to analyze the effect of local infiltration analgesia (LIA), peripheral nerve blocks, general and spinal anesthesia on early functional recovery and pain control in primary total knee arthroplasty.
Between January 2016 until August 2016, 280 patients underwent primary TKA and were subdivided into four groups according to their concomitant pain and anesthetic procedure with catheter-based techniques of femoral and sciatic nerve block (group GA&FNB, n = 81) or epidural catheter (group SP&EPI, n = 51) in combination with general anesthesia or spinal anesthesia, respectively, and LIA combined with general anesthesia (group GA&LIA, n = 86) or spinal anesthesia (group SP&LIA, n = 61). Outcome parameters focused on the evaluation of pain (NRS scores), mobilization, muscle strength and range of motion up to 7 days postoperatively. The cumulative consumption of (rescue) pain medication was analyzed.
Pain relief was similar in all groups, while the use of opioid medication was significantly lower (up to 58%) in combination with spinal anesthesia, especially in SP&EPI. The LIA groups, in contrast, revealed significant higher mobilization (up to 26%) and muscle strength (up to 20%) in the early postoperative period. No analgesic technique-related or surgery-related complications occurred within the first 7 days. Due to insufficient pain relief, 8.4% of the patients in the catheter-based groups and 12.2% in the LIA groups resulted in a change of the anesthetics pain management.
The LIA technique offers a safe and effective treatment option concerning early functional recovery and pain control in TKA. Significant advantages were shown for mobilization and muscle strength in the early postoperative period while pain relief was comparable within the groups.
Introduction
Aim of this study was to biomechanically compare two different acetabular cup fixation constructs in terms of fracture fixation for displaced acetabular fractures involving the anterior ...column with hemitransverse fracture under partial and full weight-bearing conditions.
Methods
Two different reinforcement rings designed as cages for primary THA were biomechanically tested in terms of managing a complex acetabular fracture. Single-leg stance cyclic loading was performed to assess fracture gap movement and fragment rotation. Twelve hemi pelvis Sawbones were divided into two groups: primary THA with acetabulum roof reinforcement plate (ARRP) (
n
= 6) and primary THA with Burch–Schneider reinforcement cage (BSRC) (
n
= 6).
Results
During loading under partial weight-bearing (250 N) fracture gap movement tended to be larger in the BSRC group as compared to the ARRP group. Under full weight-bearing conditions, the ARRP showed 60% significantly less motion (
p
= 0.035) of the
os ilium
to
os ischii
gap compared to BSRC. Fracture gap movements between the
os ilium
and
spina iliaca
fragments were significantly reduced by 76% (
p
= 0.048) for ARRP in contrast to BSRC. The ARRP group also demonstrated significantly less movement in the fracture gaps
os ischii
to
quadrilateral plate
(62% reduction,
p
= 0.009) and
quadrilateral plate
to
spina iliaca
(87% reduction,
p
< 0.001). Significantly less rotational movement of the
quadrilateral plate
to the
os ilium
was exhibited by the ARRP group (
p
= 0.015).
Conclusions
The presented acetabulum roof-reinforcement plate (ARRP) provides stable conditions at the acetabular component with adequate stabilization of a displaced acetabular fracture.
Abstract Bone graft substitutes often exhibit poor bone regeneration in large defects because of inadequate vascularization. Studies have shown that if blood supply is compromised, application of ...osteogenic factors alone could not induce successful healing. This study was to evaluate the effects of vascular endothelial growth factor, which combined with a coralline scaffold, on vascularization, scaffold resorption and osteogenesis in a rabbit radius critical size defect model. The scaffold was either coated with a control-plasmid DNA (group 1), coated with VEGF-plasmid DNA (group 2), loaded with mesenchymal stem cells (BMSC) transfected with control plasmid (group 3) or with both stem cells and the VEGF plasmid (group 4). X-rays were taken every 4 weeks up to week 16, when animals were euthanized. The volume of new bone was measured by μ-CT scans and blood vessels were counted after anti-CD31 staining of endothelial cells. The results from the solitary VEGF- and VEGF-transfected cells (groups 2 and 4) demonstrated significantly enhanced vascularization, osteogenesis and resorption of the carrier when compared to the control group. The highest degree of osteogenesis was found when the carrier was loaded with BMSC (group 3), whereas VEGF-transfected cells led to the highest vascularization and fastest resorption of the bone substitute. Additionally, VEGF-transfected BMSC led to a more homogenous vascularization of the defect. The results indicate that VEGF can be a helpful factor to improve healing in large bone defects, in which bone substitutes will otherwise not be vascularized and replaced by fresh bone.
A dynamic model was developed to simulate complex interactions of mechanical stability, revascularisation and tissue differentiation in secondary fracture healing. Unlike previous models, blood ...perfusion was included as a spatio-temporal state variable to simulate the revascularisation process. A 2D, axisymmetrical finite element model described fracture callus mechanics. Fuzzy logic rules described the following biological processes: angiogenesis, intramembranous ossification, chondrogenesis, cartilage calcification and endochondral ossification, all of which depended on local strain state and local blood perfusion. In order to evaluate how the predicted revascularisation depended on the mechanical environment, we simulated two different healing cases according to two groups of transverse metatarsal osteotomies in sheep with different axial stability. The model predicted slower revascularisation and delayed bony bridging for the less stable case, which corresponded well to the experimental observations. A revascularisation sensitivity analysis demonstrated the potential of the model to account for different conditions regarding the blood supply.
The treatment of distal tibia shaft fractures is still problematic because of the thin soft tissue envelope and less stable osteosynthesis. Therefore, nonunions are often seen in this region. When ...reamed nailing is performed, construct stiffness can be increased and fracture gap movement can be reduced, but in open fractures the question whether reamed nailing is before unreamed nailing is still uncertain. Therefore, unreamed nails with angle stable interlocking options were produced with the idea to improve the biomechanical properties of unreamed nails. This study compared reamed and unreamed nailing either with angle stable or conventional interlocking to plate osteosynthesis. The hypothesis was that angular stability in unreamed nailing will increase the construct stiffness and reduce the fracture gap movement.
In this study, four groups of five artificial tibiae were treated with different osteosynthesis techniques. Group 1 was treated with a reamed nailing technique, group 2 with a distally angle stable locked nail in an unreamed technique, group 3 with an unreamed nail in a conventional locking technique, and group 4 with a locked medial plate system. After osteotomy of the intersection of the distal 4/5 to 5/5 of the tibia, stiffness of the implant-bone construct and micromovement of the fragments were measured. In addition, the range of motion at the mechanical zero under torsional load was calculated.
Biomechanical tests showed that the stiffness of the reamed nail constructs was significantly higher than the compared implants. The unreamed conventionally locked nail and unreamed distally angular stable locked nails were less stiff than the larger sized reamed nail, but the implant-bone construct showed higher stiffness values than the locked plate osteosynthesis. Regarding stiffness of the two unreamed groups, no significant differences were found. The interfragmentary movement in axial and torsional force exhibited the highest range of motion for locked plating, while the reamed nail significantly exhibited the least. The range of motion at the mechanical zero under torsional load was the lowest for the unreamed and angle stable locked nail.
Under biomechanical considerations, the treatment of distal tibia fractures using the reamed nailing technique is before unreamed nailing, but distal angle stable interlocking of the nail may also be a satisfactory method.
Abstract The progress of fracture healing is directly related to an increasing stiffness and strength of the healing fracture. Similarly the weight bearing capacity of a bone directly relates to the ...mechanical stability of the fracture. Therefore, assessing the progress of fracture repair can be based on the measurement of the mechanical stability of the healing fracture. However, fracture stability is difficult to assess directly due to various obstacles of which shielding of the mechanical properties by the fracture fixation construct is the most relevant one. Several assessment methods have been proposed to overcome these obstacles and to obtain some sort of mechanical surrogate describing the stability of the fracture. The most direct method is the measurement of the flexibility of a fracture under a given external load, which comprises the challenge of accurately measuring the deformation of the bone. Alternative approaches include the measurement of load share between implant and bone by internal or by external sensors. A direct 3 dimensional measurement of bone displacement is provided by radiostereometric analysis which can assess fracture migration and can detect fracture movement under load. More indirect mechanical methods induce cyclic perturbations within the bone and measure the response as a function of healing time. At lower frequencies the perturbations are induced in the form of vibration and at higher frequencies in the form of ultrasonic waves. Both methods provide surrogates for the mechanical properties at the fracture site. Although biomechanical properties of a healing fracture provide a direct and clinically relevant measure for fracture healing, their application will in the near future be limited to clinical studies or research settings.
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