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Biomedical subjects

A Toni

Publications and source records attributed to A Toni.

At least 145 records · Page 8Linked to original sources
PubMedDate not supplied

Experimental study on the cement mantle in hip arthroplasty: effect of defects on the property of the materials used.

The study simulated implantation of a hip prosthesis stem in the femur. The cement mantle produced in vitro was observed under an optic microscope. A higher concentration of porosity in the cement mantle at the stem-cement interface was observed. By heating the stem to 45 degrees C and 55 degrees C the authors observed a reduction in porosity in the three surfaces examined: stem-cement interface, internal surface, and cement-pseudofemur interface. Heating of the stem causes a reduction in polymerization time and an increase in maximum temperature achieved during the polymerization process. A reduction in porosity at the stem-cement interface influenced bending strength of the specimens extracted from the mantle. A significant difference between resistance to flexion in the specimens produced with the stem at 55 degrees, and in those with the stem at 23 degrees C was observed.

Arthroplasty, Replacement, Hip↗
PubMedDate not supplied

Cementless hip arthroplasty with a modular neck.

The authors report the preliminary results obtained in 347 prosthetic implants with hip arthroplasty with a modular neck. The advantages to using this method are related to the chance to adapt to different anatomical conditions: in particular, in primary arthroplasty a straight neck was used in the majority of cases (83%), while in dysplastic hips a straight neck was used in 47.5% of cases and a retroverse neck (8 degrees or 15 degrees) overall in 40% of cases.

Adolescent↗
PubMedDate not supplied

Fracture prediction for the femoral neck using finite element models.

Fracture of the femoral neck is an important clinical, social and economic topic. Prediction in subjects who are at risk for this type of fracture has been the object of numerous studies. Nonetheless, the methods of classification based on densitometric indicators alone have shown poor accuracy. It is the purpose of this study to propose a method to obtain an estimate of the resistance of the proximal femur, and to improve accuracy in prediction in subjects who are at risk for fracture. Based on the densitometric dataset alone, a bidimensional finite element model was developed that takes into account the distribution of density together with the femoral anatomy and the typical conditions of trauma. The model was applied to a group of preliminary osteoporotic patients. The statistical classification showed an increase in accuracy by 13%, as compared to a classification based on densitometric indicators alone.

Adult↗
PubMedDate not supplied

The use of extra-long stems in total hip reimplantation.

The authors report their experience in the use of extra-long stems for total hip reimplantations, and they then compare them with the results obtained when short or standard stems were used. The use of the extra-long stem is reserved for special cases, such as those where there is osteolysis extending to the proximal femur and diaphysis, distal diaphyseal fractures, and when the trans-femoral technique is used to remove the stem. A total of 246 prosthetic stem reimplantations were carried out between 1985 and 1999, and in most of the cases (86.2%) the cause of reimplantation was aseptic loosening of the stem alone or of both prosthetic components, while in the remaining cases it involved the sequelae of endoprosthesis or cotyloiditis (8.5%), the sequelae of septic explantation (2.1%), breakage of the prosthetic head and cone wear (1.2%), breakage of the prosthetic stem (0.8%), fracture of the femoral diaphysis on a loosened cemented prosthesis (0.4%), breakage of the prosthetic neck (0.4%), dislocation of the prosthesis (0.4%). A stem equal to or longer than 22 cm had to be used in 13 cases (5.3%), while a short stem (12-13 cm) or a standard stem (17-18 cm) was sufficient in the remaining 233 cases. The results were worse for the extra-long stem group as compared to those for the short/standard group; that is, there was 1 case (7.7%) of septic loosening that resulted in explantation, as compared to 2.6% (6 cases) of explantation resulting from aseptic loosening (3 cases) or septic loosening (3 cases) of the short/standard group. As concerns radiographic assessment, extra-long stems show bone stability in 69.2% of cases, fibrous in 23.1%, and loosened in 7.7%, while 97.7% of short/standard stems show bone stability, 0.9% fibrous stability, 1.4% instability.

Arthroplasty, Replacement, Hip↗
PubMedDate not supplied

Radiographic and therapeutic aspects of neurogenic arthropathy.

The authors describe the typical radiographic aspects of neurogenic arthropathy based on an examination of 127 cases observed at the Rizzoli Orthopaedic Institute. Surgical indications for the various joints affected are discussed, and the results obtained after treatment are reported.

Adult↗
PubMedDate not supplied

Cellular reactions in hip prosthesis loosening.

Based on the results obtained in histological examinations carried out on periprosthetic tissues in a large series of cases of prosthetic hip joint explants, the authors analyze the cellular events that may occur in loosening phenomena as compared to what occurs in the paraphysiological repair process that is observed in the stable prosthesis. Like other authors, they believe that the principal role in the mechanism of loosening is played by macrophages which are recalled in a large number, at times together with multinucleate giant cells, at the bone-implant interface, after micromovements of the prosthesis and the formation of wear particles have occurred. The macrophages would be capable of favoring resorption of the periprosthetic bone tissue, producing areas of osteolysis in which the transmission of the mechanical stress of loading is modified. The ensuing prosthetic instability increases wear phenomena, causes a greater amount of osteolysis, and, in a vicious cycle, loss of the relationship between bone and implant, and, thus, prosthetic loosening. Finally, the authors report a hypothesis on the pathogenesis of the phenomenon, based on which non-physiological stress, associated with wear and eventually infection, leads to loosening.

Bone Cements↗
PubMedDate not supplied

Considerations on ceramic prosthesis explants.

The authors report data obtained for 11 cases of explants of prostheses having ceramic joint surfaces. The wear phenomena observed in 9 prostheses, including 1 case with breakage of the ceramic head, was moderate: 20-22,000 debris per mu 2. In 2 cases the wear was massive, with a concentration of debris in the peri-implant tissues 5-10 times greater (100,000-218,000 debris per mu 2). An explanation for the trigger mechanism of wear phenomena is proposed: the cases of massive wear are related to loosening of the acetabulum. A histological examination of the bone tissue surrounding a stem covered with alumina (Al2O3) carried out in three cases allowed us to observe an area of demineralization measuring approximately 500 mu of tissue in contact with the ceramic coating. The osteomalacia could be caused by the diffusion of alumina ions.

Bone Cements↗
PubMedDate not supplied

Radiographic evaluation of HDPE cemented and cementless Lord and An.C.A. screwed acetabular models.

A total of 187 alumina screwed porous-ceramic coated sockets (An.C.A.), 48 screwed smooth-surfaced Lord sockets, and 251 cemented polyethylene sockets were radiographically evaluated at an average follow-up of 30, 51 and 96 months respectively. After 6 years the Lord prostheses revealed a 38% incidence of loosening, similar to that observed for cemented sockets 10-12 years after surgery. The An.C.A. prostheses revealed radiographic loosening equal to 12% (6 cases) in the first 50 implants, and only 0.7% in the remaining 137 cases: overall, the An.C.A. acetabular prosthesis revealed an index of radiographic loosening equal to 3.3% (7/187). To guarantee "osteointegration" of the porous coating of An.C.A. sockets optimal stability must be obtained when the prosthesis is screwed in. Because the mid-term follow-up for this clinical experience is relatively short (30 months), an opinion on the reliability of the screwed "porous" sockets must await confirmation.

Acetabulum↗
PubMedDate not supplied

Femoral bone remodeling: clinical experience with cemented and cementless total hip arthroplasty.

A radiographic study of femoral bone tissue remodeling around hip arthroplasty was carried out simultaneously in two series totalling 224 cementless and 77 cemented prostheses. Remodeling was analyzed by detailed visual evaluation of the radiographic assessment. The results show that the phenomenon of bone remodeling is still evolving more than 5 years after surgery. Bone demineralization of the proximal femur is more evident in cementless prostheses than in those stabilized with acrylic cement (24% vs. 12%). The preoperative state of mineralization significantly influences bone remodeling.

Bone Cements↗
PubMedDate not supplied

Hip arthroplasty after femoral osteotomy.

Osteotomy of the proximal femur is performed to treat numerous hip pathologies in order to improve the load axis of the coxofemoral joint, thus improving coverage of the femoral head; despite this, arthrosis-related pathology may progress, and this nearly always results in hip arthroplasty. Many authors report that the time interval between osteotomy and arthroplasty is approximately 5 to 10 years. It is the purpose of this study to evaluate the complications and the clinical and radiographic results of hip arthroplasty performed after proximal femoral osteotomy, comparing them with a control group for hip arthroplasty without previous osteotomy.

Adolescent↗
PubMedDate not supplied

Computer-assisted tridimensional preoperative planning in hip revision surgery.

It is often difficult to obtain excellent clinical results in complex cases of hip replacement surgery. Over recent years, in order to improve the success rate of this type of surgery, prosthetic implants that are more ductile and more reliable have been developed. At the same time, important progress has been made in improving the accuracy of surgical method. A great deal of effort has been made to improve methods of preoperative planning. The world over, computerized systems that aid the surgeon in his or her clinical practice (CAOS systems) have been developed. The authors present Hip-op, a new CAOS type system, for preoperative planning. In particular, the use of Hip-op in some very complex cases of hip revision surgery is reported. Based on clinical experience, it is believed that Hip-op is a useful system, one that is easy to use, and that it is capable of improving the accuracy of surgery.

Adult↗
PubMedDate not supplied

Osteorticular amyloidosis in a patient under dialysis treated by total hip arthroplasty: case report and review of the literature.

The authors present the case of a patient affected by kidney failure, who had been undergoing dialysis for several years when areas of osteolysis and bone resorption in the proximal femur and pathologic fracture appeared. She was treated surgically by hybrid total hip arthroplasty. The patient also complained of pains in other joints. The bone tissue taken from the osteolytic area was examined histologically. The test showed the presence of an amyloid substance. Microradiography and X-ray diffractometry carried out on the same samples confirmed the lack of mineralisation due to the presence of aluminum ions, presumably derived from dialysis. The high concentration of this element was confirmed by resum assay with spectrophometry in atomic absorption. Considering the results of the aforementioned tests, the patient was put on dialysis using a polymethylmethacrylate filter.

Amyloidosis↗
PubMedDate not supplied

Intrapelvic migration of the prosthetic acetabular component.

The authors propose a preoperative evaluation protocol for cases of dislocation of the prosthetic cup complicated by intrapelvic migration, obtained by studying 20 cases of prosthetic loosening with protrusion of the acetabular component in the pelvis, treated by reimplantation or explantation. In all of the patients, accurate preoperative planning was carried out, because of the considerable frequency of dislocation, compression or damage to the vascular and nervous structures deriving from migration inside the pelvis of the acetabular component. The authors suggest that in all cases of acetabular loosening evaluation involve standard X-rays, bone scan with technethium99 and with marked granulocytes, CT scan. When the cup protrudes in the pelvis, prior to surgery, CT scan with contrast medium will be required, and if the risk of vascular involvement exists, angiography should also be carried out.

Acetabulum↗
PubMedDate not supplied

An evaluation of the "quoad vitam" prognosis in the elderly patient with medial fracture of the femoral neck.

The authors analyzed 425 consecutive cases of medial fracture of the femoral neck with the purpose of establishing a simple and practical system, and one which is easy to use, in order to evaluate this type of lesion and to compare different series of cases. Based on these criteria the death rate occurring intra-hospital and 6 months after trauma, the influence of the age factor, the type of anesthesia used and the type of treatment carried out, were evaluated. The results were as follows: The classification devised by the American Society of Anesthesiology continues to be an effective system for the evaluation of vital risk. The death rate was always directly related to age, and it was not influenced by either the type of anesthesia or the type of surgery used; however, it doubled when non-surgical treatment was used.

Aged↗