In vivo experimental study of the arterial supply of the rabbit posterior limb

Background: The use of bone graft has been a successful step in the treatment of a large number of diseases of the osteoarticular system. But a massive bone defect remains a dilemma for modern reconstructive surgery. Present methods used have a high level of morbidity and complication. Literature indicates the absence of an optimal solution in massive bone defects healing. The aim of this study: to perform an in vivo preliminary study of vascularization of the hind limb in the rabbit model, for obtaining a graft able for further inclusion in the host blood circulation, without immunosuppression by decellularization. Material and methods: The study was performed on the 12 laboratory rabbits. After euthanasia of the rabbit, the femoral and tibiofibular bone was collected without soft tissue, only with the vascular pedicle, and keeping the passage through the vessels. In the abdominal aorta was injected contrast material, with the subsequent preparation of the arterial vessels, succeeded by anatomical, morphological, radiography, and microangiography study of this vascularized bone segment. Results: The principal nutrient artery of the rabbit femur springs from the lateral circumflex femoral artery. The optimal segment for vascularized allografting (the rabbit model) was determined the upper third of the femur with the up to the level of the internal iliac artery. So, it could be used as a bone graft for further conservation and decellularization. Conclusions: The vascularized allogeneic bone without immunosuppression would be a perfect alternative in the treatment of the massive bone defects.

Development of Knowledge-Based Engineering System for Structural Size Optimization of External Fixation Device

The development process of the knowledge-based engineering (KBE) system for the structural size optimization of external fixation device is presented in this paper. The system is based on algorithms for generative modeling, finite element model (FEM) analysis, and size optimization. All these algorithms are integrated into the CAD/CAM/CAE system CATIA. The initial CAD/FEM model of external fixation device is verified using experimental verification on the real design. Experimental testing is done for axial pressure. Axial stress and displacements are measured using tensometric analysis equipment. The proximal bone segment displacements were monitored by a displacement transducer, while the loading was controlled by a force transducer. Iterative hybrid optimization algorithm is developed by integration of global algorithm, based on the simulated annealing (SA) method and a local algorithm based on the conjugate gradient (CG) method. The cost function of size optimization is the minimization of the design volume. Constrains are given in a form of clinical interfragmentary displacement constrains, at the point of fracture and maximum allowed stresses for the material of the external fixation device. Optimization variables are chosen as design parameters of the external fixation device. The optimized model of external fixation device has smaller mass, better stress distribution, and smaller interfragmentary displacement, in correlation with the initial model.

A New Orthodontic-Surgical Approach to Mandibular Retrognathia

(1) Background: Mandibular deficiency is one of the most common growth disorders of the facial skeleton. Recently, distraction osteogenesis has been suggested as the treatment of choice for overcoming the limitations of conventional orthognathic surgery; (2) Methods: A new custom-manufactured dental-anchored distractor was built and anchored in the first molar and lower canine. It consists of a stainless-steel disjunction screw, adapted and welded to the orthodontic bands through two 1.2 mm diameter connector bars with a universal silver-based and cadmium-free solder; (3) Results: The distractor described can be a useful tool to correct mandibular retrognathia and is better tolerated by patients, especially in severe cases; (4) Conclusions: The dental-anchored distractor increases the anterior mandibular bone segment without affecting the gonial angle or transverse angulation of the segments and avoids posterior mandibular rotation, overcoming the limitations of conventional surgical treatment.

A Matlab toolbox for scaled-generic modeling of shoulder and elbow

There still remains a barrier ahead of widespread clinical applications of upper extremity musculoskeletal models. This study is a step toward lifting this barrier for a shoulder musculoskeletal model by enhancing its realism and facilitating its applications. To this end, two main improvements are considered. First, the elbow and the muscle groups spanning the elbow are included in the model. Second, scaling routines are developed that scale model’s bone segment inertial properties, skeletal morphologies, and muscles architectures according to a specific subject. The model is also presented as a Matlab toolbox with a graphical user interface to exempt its users from further programming. We evaluated effects of anthropometric parameters, including subject’s gender, height, weight, glenoid inclination, and degenerations of rotator cuff muscles on the glenohumeral joint reaction force (JRF) predictions. An arm abduction motion in the scapula plane is simulated while each of the parameters is independently varied. The results indeed illustrate the effect of anthropometric parameters and provide JRF predictions with less than 13% difference compared to in vivo studies. The developed Matlab toolbox could be populated with pre/post operative patients of total shoulder arthroplasty to answer clinical questions regarding treatments of glenohumeral joint osteoarthritis.

Performance of a Piezoelectric Energy Harvesting System for an Energy-Autonomous Instrumented Total Hip Replacement: Experimental and Numerical Evaluation

Instrumented implants can improve the clinical outcome of total hip replacements (THRs). To overcome the drawbacks of external energy supply and batteries, energy harvesting is a promising approach to power energy-autonomous implants. Therefore, we recently presented a new piezoelectric-based energy harvesting concept for THRs. In this study, the performance of the proposed energy harvesting system was numerically and experimentally investigated. First, we numerically reproduced our previous results for the physiologically based loading situation in a simplified setup. Thereafter, this configuration was experimentally realised by the implantation of a functional model of the energy harvesting concept into an artificial bone segment. Additionally, the piezoelectric element alone was investigated to analyse the predictive power of the numerical model. We measured the generated voltage for a load profile for walking and calculated the power output. The maximum power for the directly loaded piezoelectric element and the functional model were 28.6 and 10.2 µW, respectively. Numerically, 72.7 µW was calculated. The curve progressions were qualitatively in good accordance with the numerical data. The deviations were explained by sensitivity analysis and model simplifications, e.g., material data or lower acting force levels by malalignment and differences between virtual and experimental implantation. The findings verify the feasibility of the proposed energy harvesting concept and form the basis for design optimisations with increased power output.

Outcome of modular megaprosthesis in management of Campanacci stage III giant cell tumor around the knee: a prospective study

Background: Juxta articular giant cell tumors around the knee constitute 50-60% of the total cases reported. If the disease is detected at an advanced stage, reconstruction of the joint after tumor excision poses problems and has poor functional outcome. The aim of the study was to determine the functional outcome after resection of juxta-articular giant cell tumors around the knee and its reconstruction with mega prosthetic arthroplasty will be analyzed.Methods: Between January 2017 and March 2021, 14 patients in the age group of 28-48 years (mean=42.85 years) with Campanacci stage three giant cell tumors around the knee were studied (12-distal femur patients, 2-proximal tibia). Patients underwent tumor excision and reconstruction with modular megaprosthesis. They were evaluated post-operatively using the Revised Musculoskeletal Tumor Society Score (MSTS) for lower limb. Results: All the patients were followed up for 12-44 months (mean=29.5 months), the average knee flexion at 6 months being 116.4 degrees. The mean MSTS at 6, 12, 18 and 24 months are 19.45, 23.23, 26.61 and 28.77 respectively. Complications observed were infection and tumor recurrence. Conclusions: In advanced cases where tumor excision leaves large bone segment loss, reconstruction with megaprosthesis can give desirable functional outcome.

Bacteriological Profile of Osteomyelitis in Drepanocytic Children at the David Bernardino Pediatric Hospital from May to August 2017

Introduction: Osteomyelitis is defined as the infection of the entire bone structure caused by a pyogenic infectious agent. Depending on the evolution time, clinical and radiological findings can be classified as acute or chronic. The present study aimed to describe the bacteriological profile of osteomyelitis in patients with sickle cell disease, admitted to the Pediatric Hospital David Bernardino, in Luanda/Angola, from June 1 to October 31, 2017. Methodology: We carried out a descriptive, longitudinal and prospective study in a universe consisting of 33 children with sickle cell anemia admitted to the Surgery Service of this Hospital. Sample collection was performed during the surgical procedure. Results: We identified a higher percentage of cases in male children with 58% and in the age group from 5 to 10 years with 63.6%. The most affected bone segment was the tibia with 33.4%, followed by the humerus and femur with 30.3% each. Most patients, 66.7% of cases, were admitted to the Surgery Service before the surgical procedure. Of the samples collected for bacteriological study, only 31.3% were positive, with the most identified germs being Citrobacter spp, Enterobacter species and Proteus species, with 6.1% each. The sensitivity profile of Gram positive cocci was 100% for Ofloxacin and Cloxacillin and gram negative cocci had 100% sensitivity for Ofloxacin, Amikacin and Minocycline. There was total resistance in Gram positives to Ampicillin and 80% in Gram negatives. Most children had severe anemia (hemoglobin below 9 g), in 17 cases (69.69%), Erythrocyte Sedimentation Velocity levels between 60 to 83 mm, in 16 cases (48.5%), and levels of C-Reactive Protein (CRP) between 40 to 50 mg/L in 8 cases (24.3%). Cloxacillin was used in 60.7% of cases, followed by Cloxacillin + Gentamicin in 7 children (21.1%). Twenty-seven children (82%) underwent surgical treatment, with fenestration being the most used procedure. Conclusion: The characteristics of the patients and the disease regarding sex, age and the most affected bone are in accordance with those described in the literature. Of the 10 patients without previous antibiotic therapy had samples with bacterial growth, with identification of Citrobacter spp (2), Enterobacter sp (2) Proteus spp (2), E.Coli (1), S.Aureus (1), Proteus Vulgaris (1) and Proteus Mirabilis (1). Patients were hospitalized for more than seven (7) days, due to other pathologies during hospitalization. About 60.7% of the children were treated with Cloxacillin and 21.1% with an association of Cloxacillin with Gentamicin, with surgical debridement and fenestration being the surgical procedure performed in 82% of patients. Patients operated on and undergoing targeted antibiotic therapy had good results in 87.87% of cases; One case (3.03%) required readmission and underwent a new surgical approach.

A Linkage Representation of the Human Hand Skeletal System Using CT Hand Scan Images

The present study proposed a method for establishing a linkage representation of the human hand skeletal system. Hand skeletons of 15 male subjects were reconstructed from computed tomography (CT) scans in 10 different postures selected from a natural hand-closing motion. The wrist joint center was estimated as the intersection of the centerline of the metacarpal of the middle finger and the distal wrist crease. The remaining joint centers were kinematically estimated based on the relative motion between the distal bone segment and the proximal bone segment of a given joint. A hand linkage representation was then formed by connecting the derived joint centers. Regression models for predicting internal hand link lengths using hand length as the independent variable were established. In addition, regression models for predicting the joint center coordinates of the thumb carpometacarpal (CMC) and finger metacarpophalangeal (MCP) joints using hand length or hand breadth were established. Our models showed higher R2 values and lower maximum standard errors than the existing models. The findings of the present study can be applied to hand models for ergonomic design and biomechanical modeling.

A Biomechanical Analysis of Muscle Force Changes After Bilateral Sagittal Split Osteotomy

A basic procedure affecting maxillofacial geometry is the bilateral sagittal split osteotomy. During the surgery, the bony segments are placed in a new position that provides the correct occlusion. Changes in the geometry of the mandible will affect the surrounding structures and will have a significant impact on the functioning of the masticatory system. As a result of the displacement of the bone segment, the biomechanical conditions change, i.e., the load and the position of the muscles. The primary aim of this study was to determine the changes in the values of the muscular forces caused by mandible geometry alteration. The study considered the translation and rotation of the distal segment, as well as rotations of the proximal segments in three axes. Calculations were performed for the unilateral, static loading of a model based on rigid body mechanics. Muscles were modeled as spring elements, and a novel approach was used to determine muscle stiffness. In addition, an attempt was made, based on the results obtained for single displacements separately, to determine the changes in muscle forces for geometries with complex displacements. Based on the analysis of the results, it was shown that changes in the geometry of the mandibular bone associated with the bilateral sagittal split osteotomy will have a significant effect on the values of the masticatory muscle forces. Displacement of the distal segment has the greatest effect from −21.69 to 26.11%, while the proximal segment rotations affected muscle force values to a less extent, rarely exceeding 1%. For Yaw and Pitch rotations, the opposite effect of changes within one muscle is noticed. Changes in muscle forces for complex geometry changes can be determined with a high degree of accuracy by the appropriate summation of results obtained for simple cases.