PubMed Health⌕ Search

Biomedical subjects

F Seral

Publications and source records attributed to F Seral.

At least 19 recordsLinked to original sources
PubMed2005

A comparative FEA of the debonding process in different concepts of cemented hip implants.

Debonding of the stem-cement interface and damage accumulation in the cement mantle are basic events that contribute to the long-term failure of cemented hip reconstructions. In this work, a numerical study with these two processes coupled is presented. On the one hand, debonding of the stem-cement interface was simulated by means of a cohesive surface theory that was implemented into an interface finite element. This interface model includes a tensile-shear behavior law, the fatigue failure of the interface, and the friction evolution between both surfaces. On the other hand, damage accumulation in the cement was formulated through the theory of continuum damage mechanics, considering cement damage due to tension, creep under compression, crack closure effects, non-linear damage accumulation and cement residual stresses appearing during polymerisation. This methodology was applied to simulate and compare the degradation process of the cement and stem-cement interface in four different concepts of design: Exeter, Charnley, Elite Plus and ABG II stems. As the actual mechanical properties of the surface of each specific prosthesis are not known, we assumed the same for all of them, distinguishing between polished and matt surfaces. With this assumption, the predicted results showed that the debonding process is very different for each implant depending on the stem geometry. Lower cement deterioration was obtained for the Exeter and ABG II stems, while the lowest stem-cement interface debonding was produced in the Exeter and the Elite Plus stems.

Biomechanical Phenomena↗
PubMed2004

Finite element study of intramedullary osteosynthesis in the treatment of trochanteric fractures of the hip: Gamma and PFN.

The ongoing debate surrounding the surgical treatment of trochanteric hip fractures, particularly unstable fractures, has led to continuous changes in the design of well-established implants and to the development of new ones. The goal of this paper was to use a finite element simulation to compare the biomechanical behaviour of two intramedullary implants most often used at the University Hospital of Zaragoza: the standard Gamma nail (Howmedica) and the proximal femoral nail (PFN, Stratec). The main focus was on the displacements of the fracture focus and the stress distributions along the femur and the implant. Both nails produced an important redistribution of stress in the bone tissue, but the redistribution of peak stress was higher for the Gamma nail. On the other hand, with PFN there were smaller displacements at the fracture site. Finally, under the same workload, the Gamma nail supported higher stresses than the PFN.

Aged↗
PubMed2004

A comparative analysis of different treatments for distal femur fractures using the finite element method.

The main objective of this work is the evaluation, by means of the finite element method (FEM) of the mechanical stability and long-term microstructural modifications in bone induced to three different kinds of fractures of the distal femur by three types of implants: the Condyle Plate, the less invasive stabilization system plate (LISS) and the distal femur nail (DFN). The displacement and the stress distributions both in bone and implants and the internal bone remodelling process after fracture and fixation are obtained and analysed by computational simulation. The main conclusions of this work are that distal femoral fractures can be treated correctly with the Condyle Plate, the LISS plate and the DFN. The stresses both in LISS and DFN implant are high especially around the screws. When respect to remodelling, the LISS produces an important resorption in the fractured region, while the other two implants do not strongly modify bone tissue microstructure.

Aged↗
PubMed2000

Tenosynovial chondromatosis of the third finger.

Synovial chondromatosis is an uncommon lesion, characterised by cartilaginous and osseous metaplasia of the joint synovium. It usually involves a large joint and rarely occurs in the hand. A case of tenosynovial chondromatosis of the third finger is reported.

Chondromatosis, Synovial↗
PubMed2000

Three-dimensional finite element analysis of several internal and external pelvis fixations.

The Finite Element Method (FEM) can be used to analyze very complex geometries, such as the pelvis, and complicated constitutive behaviors, such as the heterogeneous, nonlinear, and anisotropic behavior of bone tissue or the noncompression, nonbending character of ligaments. Here, FEM was used to simulate the mechanical ability of several external and internal fixations that stabilize pelvic ring disruptions. A customized pelvic fracture analysis was performed by computer simulation to determine the best fixation method for each individual treatment. The stability of open-book fractures with external fixations at either the iliac crests or the pelvic equator was similar, and increased greatly when they were used in combination. However, external fixations did not effectively stabilize rotationally and vertically unstable fractures. Adequate stabilization was only achieved using an internal pubis fixation with two sacroiliac screws.

Aged↗
PubMed1998

Experimental model of multidirectional disc hernia in rats.

We have carried out an experimental investigation of lesions of the intervertebral disc produced by flexion, lateral bending and rotational forces in an attempt to produce disc herniations. Adult Wistar rats were divided into 4 groups: control and posterior, lateral and rotational herniation. There were 10 rats in each group. The tail between the 5th and 8th vertebral segments was used. A Kirschner wire was inserted into each of 2 adjacent vertebrae and the movement produced had an apex which was anterior or lateral depending on the group involved. Variables such as rupture of the annulus, the cellularity of the nucleus pulposus and the site of the lesion in the disc were studied histologically. The height of the disc, the protrusion, the thickness, and the surfaces of the annulus fibrosus and the nucleus pulposus were measured. In every case we found a nuclear displacement which did not become a protrusion. The surface parameters and the cellularity of the nucleus pulposus are most useful indicators and should be included in any study examining the disc after the injection of substances for treatment.

Animals↗
PubMed1998

Absorbable screws through the greater trochanter do not disturb physeal growth: rabbit experiments.

We studied the effect of implantation of self-reinforced polyglycolic acid (SR-PGA) screws through the greater trochanter in rabbits. 15 rabbits aged 10 weeks had an SR-PGA screw inserted through the left trochanter physis. A similar drilling was made through the right greater trochanter without screw implantation. The animals were assigned to 3 groups of 5, and were killed after 1, 2 or 3 months. Radiographs of both femurs were obtained monthly and the articulo-trochanteric distance and the neck-shaft angle were measured. After killing the animals, a histological study was performed. The drilling on the right trochanter generated a bony bridge in all the animals. The SR-PGA screws did not give rise to an epiphysiodesis. The progressive peripheral degradation of the implants gave rise to the formation of only modest bridges, which were smaller in size than those observed in the control trochanter. Our findings suggest that absorbable PGA screws implanted through a growth plate cause only minor bone formation and no epiphyseodesis.

Animals↗
PubMed1997

Adherence of Staphylococcus aureus slime-producing strain variants to biomaterials used in orthopaedic surgery.

The adherence of Staphylococcus aureus to biomaterials used in orthopaedic surgery (polymethylmethacrylate, fresh bone, steel and titanium alloys) and to glass was studied in vitro at 1, 2, 6, 24 and 48 h of incubation. Nonslime-producing strains (72, 80 and 510) and slime-producing variants of these strains were used. An automated and fast method of ATP-bioluminiscence was applied to determine bacterial viability. The lowest adherence corresponded to polymethylmethacrylate and bone, and the highest to metals. Significant adherence was detected in all cases after 6 h and was strain dependent, being lowest for strain 72. In most cases, adherence of nonslime-producing variants was not significant compared with controls, and slime-producing were more adherent than nonslime-producing variants. These differences were maximal at 6 h or 48 h, depending on the strain and the material. The findings suggest that the appearance of slime-producing cells within a given nonslime-producing bacterial population may jeopardise postoperative immune systems and antibiotic efficacy as a consequence of biofilm formation on implants and prostheses.

Analysis of Variance↗
PubMed1996

Complications and technical problems with the gamma nail.

A retrospective review of complications with the gamma nail has been carried out in 152 patients with stable and unstable pertrochanteric fractures. Operative complications occurred in 10 patients. Screws penetrated the femoral neck in 3, immediate varus was associated with a short screw in 2, diaphyseal fractures occurred at the site of the distal screws in 3 and comminuted femoral fractures in 2. Fifteen patients (10.5%) died in hospital. At follow up, pseudarthrosis was present in 2 cases and fractures of the femoral shaft in 4. The incidence of complications could be reduced by using of shorter nails, less valgus angulation and by not introducing distal screws unless essential.

Aged↗
PubMed1994

Subcapital stress fracture of the femoral neck after total knee arthroplasty.

Although total knee arthroplasty is a valuable surgical technique, complications and problems do occur. Associated stress fracture of the femoral neck is relatively rare and we have only found eleven relevant reports. In this paper we present a case of bilateral total knee arthroplasty where three months after the second replacement, and without significant injury, the patient suffered a femoral neck fracture in the limb which had received the first new knee joint.

Aged↗
PubMed1992

Five-year follow-up evaluation of the noncemented press-fit titanium hip-joint endoprosthesis.

A series of 260 noncemented total hip arthroplasties with a titanium alloy stem and fixation by the Zweymüller press-fit and an Endler polyethylene threaded cup was reviewed in detail. The minimum follow-up period was 48 months and the maximum 72 months, with an average of 60 months. A scale from zero to five points was applied to evaluate pain, mobility, and motion for a total possible accumulation of 15 points. The global results of the different etiologic groups (arthrosis, femoral head necrosis, rheumatoid arthritis, and subcapital hip fractures) have been very good and good (12-15 points) in 67.5% of the cases and fairly good and bad in 32.3%. These results have been better in femoral head necrosis than in arthrosis or rheumatoid arthritis, but not as good in subcapital hip fractures. The age groups below 60 had better results than the above 60 groups. The Singh index higher than 3 was correlated with better-than-average results. The polyethylene cup migrated horizontally (more than 4 mm) in 7.6% of the cases and vertically (more than 5 mm) in 10%. The non-evolutionary cortical remodelation of the femur does not influence the results. Prosthetic stem sinking less than 4 mm has been found in 62% of the cases, from 4 to 9 mm in 21%, and greater than 9 mm in 6%. No alterations with clinical consequences attributable to stress-shielding have been detected.

Adult↗
PubMedDate not supplied

Bizarre parosteal osteochondromatous proliferation. Difficulty in diagnosis.

Nora's tumor, also known as bizarre paraosteal osteochondromatous proliferation, is an exophytic outgrowth from the cortical surface that consists of a mixture of bone, cartilage, and fibrous tissue. It is a benign lesion with atypical microscopic features and a tendency to recur. Nora reported 35 cases emerging from the bones of the hands and feet. The largest published series is of 65 cases, with 17 lesions involving the long bones. With this exception, most authors report isolated cases. Age range from 8 to 74 years but most patients are between 20 and 35 years of age, and with the lesion affecting males and females in equal proportions. Usually the presenting symptoMs are due to bony mass, with a variable growth rate (months-years), and infrequent pain. In 15-20% of the cases there was trauma in the patient history: nevertheless, Fechner and Mills report no association with trauma. Radiography shows a calcified, rounded mass emerging directly from the surface of the bone. Isotope bone scans show intense tracer uptake in the lesion. With time, the appearance progresses to the more characteristic mature bone architecture.

Adult↗
PubMedDate not supplied

Results in displaced radial neck fractures in children. Metaizeau technique versus arthrotomy.

The aim of the present article is to ascertain the differences between two surgical treatments commonly used in displaced radial neck fractures in children. We report the retrospective results of 20 displaced radial neck fractures with > 30 degrees of tilt (Judet grades 3-4) in children aged between 7 and 14 years treated with closed intramedullary pinning according to the Metaizeau technique (6 cases) or with arthrotomy and pinning (14 cases). Sex distribution was 14 girls and 6 boy. The average follow-up was 43 months. We found no relationship between delay in the surgical treatment and functional results. On the other hand, a relationship between residual final tilt and poorer functional results appears. The Metaizeau technique produced better results and fewer complications than arthrotomy and pinning, and, in our opinion, is the treatment of choice in this type of fracture.

Adolescent↗
PubMedDate not supplied

Results of the surgical treatment of Lisfranc fracture-dislocations.

The authors present a series of 25 patients with Lisfranc fracture-dislocation who were treated by reduction (open or closed) and stabilization with Kirschner wiring. Minimum follow-up was two years. The dislocations were divided based on the Quenu and Kuss classification system. Nonsurgical reduction was possible in 17 patients. Neither the type of dislocation nor the type of reduction influenced the results in progression in our series. Nonetheless, long-term functional results were better when the quality of the reduction was excellent.

Adolescent↗