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Biomedical subjects

V L Fornasier

Publications and source records attributed to V L Fornasier.

At least 37 records · Page 2Linked to original sources
PubMed1994

Fixation with biodegradable devices of acetabular components in a canine model.

Cementless total hip arthroplasty was performed in 13 dogs. The acetabular component was anchored with two biodegradable devices (polylactic acid) in seven dogs and with two titanium screws in six dogs. At 14 weeks, histomorphometric determinations of bony ingrowth into the porous coating of the acetabular weight bearing dome was 54.4% when fixed with the biodegradable devices and 58.9% when fixed with the titanium screws (no statistically significant difference; p = 0.556). At the sites of fixation, less bony ingrowth occurred with the biodegradable devices. The use of biodegradable devices in total hip arthroplasty should overcome the potential metal corrosion of titanium screws that can lead to polyethylene wear.

Animals↗
PubMed1993

Histological reaction to titanium alloy and hydroxyapatite particles in the rabbit tibia.

The interfacial membrane harvested from failed joint replacements contains particulate debris from the materials used for the implant. To define the tissue response to particulate titanium alloy and hydroxyapatite (HA) alone, 16 mature New Zealand white rabbits were divided into 2 groups of 8 rabbits. Using sterile technique, a drill hole was placed anteromedially in the tibia, 1 cm distal to the knee joint bilaterally. The marrow was scooped out and 0.25 mg of either titanium alloy particles or HA particles were inserted in the right tibia. The titanium alloy particles had a diameter averaging 4.0 +/- 4.4 microns (mean +/- standard deviation) and an aspect ratio (the ratio of the maximum length divided by the maximum width) of 1.84. The HA particles had a diameter of 4.4 +/- 3.3 microns and an aspect ratio of 1.76. The left leg was prepared in a similar fashion, but no biomaterial was implanted. The animals were killed after 16 wk. The harvested tibiae were processed with decalcification and the plastic-embedded sections were subjected to histomorphological analysis. Black titanium alloy particles were present within the bone marrow fat between haematopoietic cells, and within scattered macrophages. The surrounding bone appeared to be unaffected. Within the spongiosa, the HA particles were surrounded by small numbers of mononuclear histiocytes or encased within a shell of new appositional bone. Where HA deposits were exposed to the endosteal aspect of bone, there was scalloping of the surface of the HA in a pattern suggestive of resorption or dissolution of the HA particles.(ABSTRACT TRUNCATED AT 250 WORDS)

Alloys↗
PubMed1993

Radiological and histological study of aseptic loosening using a cemented tibial hemiarthroplasty in the rabbit knee.

Fourteen mature New Zealand white female rabbits had a unilateral cemented, stemmed, titanium, condylar-type tibial hemiarthroplasty, using an anteromedial arthrotomy of the right knee. The articular cartilage and minimal bone were resected. There were two prosthetic groups of seven animals each: a well-fixed, non-loose group and a loose group. In the non-loose group, the implant was inserted into the cement bed and axially compressed until the PMMA had cured. In the loose group, the same volume of cement was allowed to cure on the implant ex vivo; the prosthesis was then implanted to ensure that it was loose fitting. Radiographs were performed at zero and 3 months and graded for new lucent lines. Histological analysis was performed using undecalcified coronal sections, surface stained with toluidine blue with the prosthesis in situ, and the cement mantle preserved. Back-scattered electron microscopy was also performed. The mean cumulative grading of new lucent lines was 0.3 +/- 0.1 for the non-loose group and 2.2 +/- 0.4 for the loose group (P < 0.005). Non-loose prostheses were surrounded by a thin fibrous membrane or bone. Loose prostheses were surrounded by a thicker, fibrous tissue layer, containing histiocytes and giant cells which were more prevalent around cement particles, especially near the prosthetic tip. These findings parallel the histology found at cemented prosthetic interfaces in humans. The results of this study suggest that the fibrohistiocytic membrane commonly found around loose cemented implants may be the result of, rather than the cause of, the loosening process.

Animals↗
PubMed1993

Bone accretion around polymethylmethacrylate and polyethylene implanted in the rabbit tibia.

This study examines the accretion rate of bone surrounding orthopaedic polymeric implants in different physical forms. Forty mature, female, New Zealand white rabbits were used in the study. Bilateral 6mm drill holes were made in the anteromedial tibias, 1cm from the joint line. The right tibia received a polymeric implant and the left tibia functioned as a prepared but nonimplanted control. The animals were allocated as follows: Group 1--bulk, preformed cooled polymethylmethacrylate (PMMA) plug; Group 2--bulk, doughy PMMA implant; Group 3--cement polymer powder; Group 4--bulk ultra-high-molecular-weight polyethylene (UHMWP) plug; Group 5--UHMWP particles averaging 67.29 mum; Group 6--UHMWP particles averaging 15.68 mum. All animals received the same volume of PMMA or UHMWP. The animals were killed after four months by barbiturate overdose. Beginning four weeks prior to sacrifice, the animals were given tetracycline injections at two-weekly intervals for two consecutive days. The upper tibias were harvested bilaterally and the specimens were processed undecalcified. Using a fluorescent microscope, the distance between successive tetracycline bands was assessed. Doughy PMMA tended to suppress bone formation compared to the control side, whereas preformed PMMA plugs and particulate PMMA polymer did not. This may be due to the heat of polymerization or to the presence of residual monomer in the doughy group. Polyethylene tended to facilitate bone accretion whether in bulk or particulate form when compared to the control side or to doughy cement. This effect was less marked when the cement was in particulate form.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Osteoid osteoma of the elbow: a report of six cases.

We report six cases of osteoid osteoma of the elbow. Elbow pain was the presenting complaint in all of these young adult patients. A variety of diagnoses were entertained, and four patients underwent surgical procedures that were not helpful. Although an abnormality was identified on plain x-ray films, tomograms and a bone scan were helpful in isolating the lesion. A CT scan proved valuable in two cases. Complete en bloc excision relieved pain and improved function in each case.

Adolescent↗
PubMed1991

Wound healing complications in soft tissue sarcoma management: comparison of three treatment protocols.

A prospective, nonrandomized comparison of three treatment protocols was undertaken in 45 patients with soft tissue sarcoma designated preoperatively as being at high risk of wound healing complications. All patients underwent complete resection of the gross tumour mass (5 with positive and 40 with negative microscopic margins). Fourteen patients received postoperative adjuvant irradiation (group I), 16 preoperative irradiation (group II), and 15 preoperative irradiation and vascularized tissue transfer to the surgical bed after resection (group III). Major wound healing complications (defined as complications requiring at least 1 further surgical procedure) were lower in group III patients (chi-square = 5.57, P less than 0.03), as was the mean postoperative hospital stay (P less than 0.02, analysis of variance), and the mean number of secondary surgical procedures. Multivariate analysis showed that the only variable influencing length of stay was the use of tissue transfer. Careful intraoperative assessment of the adequacy of resection is essential prior to performing vascularized tissue transfer to ensure that tumour contamination of the donor site is avoided. Since this study is a nonrandomized clinical trial using sequential distribution of patients to the treatment groups, the data should be considered as preliminary, rather than definitive, evidence of the efficacy of vascularized tissue transfer.

Combined Modality Therapy↗
PubMed1991

Functional outcome in patients treated with surgery and irradiation for soft tissue tumours.

One hundred five consecutive patients underwent surgical resection and adjuvant irradiation in treatment of soft tissue sarcoma or aggressive fibromatosis. All patients were entered in a prospective study evaluating functional outcome and 88 patients were examined at 12 months following surgery. Outcome was characterized using the Enneking system as well as documenting employment/recreational status and limb edema. Sixty-eight of 88 patients had functional scores of 21 or better (out of a possible total of 35). Forty-four patients were serially evaluated at 12 and 24 months and there was no difference in their outcome at the 2 time points. Univariate analysis demonstrated that large tumour size, postoperative complications, and neural sacrifice were associated with poor functional outcome.

Adolescent↗
PubMed1991

Quantitative comparison of the histological effects of particulate polymethylmethacrylate versus polyethylene in the rabbit tibia.

Fourteen mature female New Zealand White rabbits underwent implantation of Simplex polymethylmethacrylate (PMMA) powder or particulate (average 67 microns) ultrahigh-molecular-weight polyethylene (UHMWPE) through a drill hole in the proximal right tibia. The left tibia functioned as a prepared but nonimplanted control. Animals were killed after 16 weeks. Histological examination of the bone-implant interface in the particulate PMMA group disclosed a florid foreign-body reaction with the presence of giant cells and histiocytes. The particulate UHMWPE group demonstrated positively birefringent UHMWPE fragments, rimmed by foreign-body giant cells and histiocytes, embedded in a loose connective tissue stroma. UHMWPE interfaces were thicker and contained more histiocytes and fibrocytes; PMMA interfaces contained more marrow cells and lymphocytes. This study underscores the importance of biomaterial debris in the process of aseptic loosening of cemented joint arthroplasties.

Animals↗
PubMed1991

Preoperative and postoperative irradiation of soft tissue sarcomas: effect of radiation field size.

For the treatment of soft tissue sarcomas it has frequently been staged but not quantitatively demonstrated, that the volume irradiated is smaller when irradiation is given preoperatively as compared to postoperatively. In this study the field size used for preoperative irradiation was compared with that necessary in the same patient had the radiation been given postoperatively. Twenty-six patients with soft tissue sarcomas of the extremity, groin, and shoulder girdle who had received preoperative irradiation were resimulated following surgery to determine the size of the postoperative field. The simulation was performed by a physician not involved in the preoperative treatment planning. Preoperatively a radial margin of 5 cm around the tumor was used for low and intermediate grade and 7 cm for high grade sarcomas. Postoperatively the same margins were used but around the surgical field. Twelve patients underwent a wide resection and 14 patients a resection followed by vascularized tissue transfer to the surgical bed. The median follow-up was 22 months (range 13-46). No local recurrences and two cases of distant metastasis were observed. Independently of surgical procedure and tumor grade, the size of the preoperative radiation field and number of joints included in the field were significantly smaller than that of postoperative radiation (p less than 0.001). In two patients preoperatively and four patients postoperatively, the radiation field involved the whole circumference of the limb. Provided that equivalent radiation time-dose-fraction parameters are used and that the complication rate is proportional to the radiation field size, late complications may be less after preoperative irradiation than after post-operative irradiation.

Adolescent↗
PubMed1991

Mechanical overload of a single compartment induces early degenerative changes in the rabbit knee: a preliminary study.

The purpose of this experiment was to determine whether mechanical overload of a single compartment of the knee in rabbits via proximal tibial osteotomy could produce early changes consistent with degenerative arthritis. Ten New Zealand white female rabbits were allocated into two groups. Group 1 (five animals) underwent a right 20 degrees valgus proximal tibial osteotomy to overload the lateral compartment of the knee. Group 2 (five animals) underwent a tibial osteotomy without malalignment (sham controls). The osteotomies were stabilized with a mini AO/ASIF plate and screws, allowing early mobilization. The left leg in each animal was left intact and served as a control. Animals were sacrificed after 3 months. Histological grading of the cartilage was performed according to Mankin et al. The mean histological gradings for the right minus the left knee were the same for the lateral and medial compartments in the 0 degrees sham osteotomy group. However, the mean histological grading of the "overloaded" lateral compartment was 2.4 times greater than the medial compartment in the 20 degrees valgus osteotomy group. These findings suggest that histological evidence of degenerative changes can be surgically induced in the rabbit knee by creating a biomechanical overload of one compartment.

Animals↗
PubMed1991

Response of the articular cartilage to weight-bearing: comparison of hemiarthroplasty with ceramic and cobalt-chromium head in dogs.

The advantages of the use of ceramic in prosthetics are well-known, especially the fact that the coefficient of friction is significantly lower at the bone-ceramic interface than at the bone-metal interface. For this reason, ceramic is used for the cephalic component of the hemiarthroplasty. The advantages of ceramic, however, are purely theoretical, and have never been scientifically proven. The aim of our study, conducted on 20 dogs, was to observe the long-term effects of femoral prosthesis with a ceramic or cobalt-chromium cephalic component upon the acetabular cartilage. Our research was conducted on homogeneous groups of dogs under similar conditions. At 8 months, the results showed evident cartilage damage that was equal in both groups. We therefore conclude that as far as everyday wear neither material is favored over the other.

Acetabulum↗
PubMed1990

The histological effects of the implantation of different sizes of polyethylene particles in the rabbit tibia.

This study examines the histological effects of different sizes of polyethylene particles implanted into the rabbit tibia. Seventeen mature New Zealand white female rabbits were allocated into three groups. Group 1 (5 rabbits) received polyethylene particles averaging approximately 16 microns in diameter, implanted into the right proximal tibia through a drill hole. Group 2 (5 animals) received particles averaging 26 microns, and Group 3 (7 rabbits) received particles averaging 67 microns. The left tibia was drilled but not implanted. Animals were sacrificed after 16 weeks. Histological analysis disclosed decreased hematopoietic activity within the left tibial drill hole. In all groups, the right tibia demonstrated positively birefringent polyethylene particles surrounded by, and within (smaller particles), histiocytes and giant cells in a fibrous tissue stroma. Statistical analysis disclosed more fibrocytes and less marrow cells at the interface of Group 3 (largest particles) compared to Group 1 and 2. Larger polyethylene particles, being less readily phagocytosed, appear to produce more fibrous encapsulation, compared to particles of a smaller size. The histological reaction stimulated by the different sizes of polyethylene particles resembled the membrane surrounding loose joint arthroplasties in humans.

Animals↗
PubMed1990

The effects of bulk versus particulate titanium and cobalt chrome alloy implanted into the rabbit tibia.

Twenty-eight mature New Zealand white female rabbits were allocated into 4 groups of 7 rabbits. Group 1 received a coiled wire of cobalt chrome alloy (Vitallium) (16 gauge x 1 cm). Group 2 received an equal weight of cobalt chrome particles averaging 15.4 microns in diameter. Group 3 received a coiled wire implant of commercially pure (C.P.) titanium (16 gauge x 1 cm). Group 4 received the same weight of C.P. titanium particles averaging 3.8 microns. The implants were placed through a drill hole in the proximal right tibia; the left tibia served as a prepared but nonimplanted control. The animals were killed after 16 weeks and quantitative histology was performed on undecalcified sections of the implant area. Bulk cobalt chrome and titanium implants were surrounded by a thin, incomplete, fibrous tissue layer with decreased numbers of cells. Trabeculae of bone were present within this connective tissue envelope. Fingerlike projections of bone enveloped the implant where it abutted endosteal bone. Clumped and loosely scattered cobalt chrome and titanium particles were surrounded by a minimal amount of fibrous connective tissue. Smaller particles were present within cells. Hematopoietic cells abutted the bulk or particulate implants directly. There was no evidence of acute or chronic inflammation or foreign body reaction. These results should be contrasted with those of Howie et al. in which intraarticular cobalt chrome particles stimulated a rapid proliferation of macrophages and synovial degeneration after 1 week. This may be due to a direct toxic effect of metals in an intra-articular environment, the smaller particle size used in that study, or to abrasive injury to the hyaline cartilage and subsequent synovitis. Our results underscore the general inert properties of these metals in the short term, when implanted into bone in the sizes and physical forms chosen.

Animals↗
PubMed1990

Spinal metastases: the obvious, the occult, and the impostors.

Spines from 832 deceased patients with a terminal diagnosis of malignant neoplasm were examined grossly, microscopically and radiographically for evidence of tumor. Gross tumor and bone destruction or sclerosis were reliable signs of obvious metastases. Occult lesions visualized on gross sagittal sections but not detectable radiographically occurred in 26% of spines with confirmed metastatic deposits. Vertebral collapse was not a reliable indicator of metastases. Collapse was not caused by neoplasm in 22% of cases. Overall, metastases were found in 36% of patients dying from neoplastic disease. Although most metastases are obvious, occult lesions not visible radiographically occur. Collapsed vertebra may be impostors simulating metastatic disease.

Diagnosis, Differential↗
PubMed1989

Non-neurogenic soft tissue tumours of the axilla: prospective review of 16 cases.

Sixteen consecutive patients entered in a prospective study of non-neurogenic soft tissue tumours had lesions in the axilla. Delayed diagnosis and inappropriate biopsy prior to referral to a surgical oncologist were frequent findings. Sarcoma and fibromatosis were diagnosed in 14 cases, and the approaches used for these two diseases were fundamentally different. The functional outcome with limb salvage surgery in these patients is presented.

Adolescent↗
PubMed1989

The histology of a failed shelf procedure.

Clinical, radiographic and histologic findings are reported in a patient who underwent a hip shelf procedure 24 years previously. While the histologic observations confirm the presence of metaplasia of the surgically formed articular surface to fibrocartilage, there are superadded degenerative changes morphologically similar to those seen in degenerative arthritis.

Adult↗