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Biomedical subjects

C E Brooks

Publications and source records attributed to C E Brooks.

17 recordsLinked to original sources
PubMed2001

Primary cementless total hip arthroplasty using a modular femoral component: a minimum 6-year follow-up.

We evaluated 59 hips that underwent a primary total hip arthroplasty using an S-ROM modular femoral component at a mean follow-up of 101 months (range, 72-145 months). All cases showed radiographic evidence of bone ingrowth, and there were no femoral revisions for aseptic loosening. The Harris hip score improved from a mean of 40 preoperatively to 89 at final follow-up. Some degree of proximal femoral disuse atrophy from stress shielding occurred in 46 hips (78%), and some degree of femoral osteolysis occurred in 25 hips (42%). Only additional follow-up will reveal whether there is a consequence of both types of proximal femoral bone loss.

Adolescent↗
PubMed1999

Temporal changes of periprosthetic bone density in patients with a modular noncemented femoral prosthesis.

Bone mineral density changes surrounding a porous-coated proximal modular sleeved hip prosthesis were determined as a function of time over a 24-month period. The periprosthetic bone regions were defined by the 7 Gruen zones. Measurements were obtained with a dual-energy x-ray densitometer using a dedicated software program. Inclusion criteria required that the patients had primary implants, were asymptomatic with Harris hip scores of > or =95 for the duration of the study, and showed no radiographic evidence of loosening. The protocol specified that bone measurements be obtained within 1 week after surgery as a baseline reference and at 3, 6, 9, 12, 18, and 24 months thereafter. A total of 111 consecutive patients were enrolled in this ongoing prospective study, of whom 52 had 4 or more measurements after the initial baseline determination for statistical analysis. At 3 months, all zones showed a significant decrease in bone mineral density relative to the baseline measurements, and their mean loss ranged from 6.5% to 11.2%. By 24 months, mineral losses relative to baseline varied from 0 to 11% for Gruen zones 1 to 6. Relative to the 3-month levels, there was no significant change in zones 1, 4, and 6; a significant improvement in zones 3 and 5; and a small but significant loss in zone 2 at 24 months. Gruen zone 7, the medial femoral neck cortex, differed in that it was the site of greatest bone mineral loss, attaining a mean of 20.2% at 24 months. It was found that the amount of periprosthetic mineral loss at 12 months was independent of the initial baseline reference bone mineral levels. Results of this study show the normal temporal bone mineral changes surrounding a proximally modular porouscoated femoral implant. The pattern of change demonstrated may be peculiar to the prosthesis used in this study because it might differ in implants of different design and material composition.

Absorptiometry, Photon↗
PubMed1997

Effect of tourniquet use on blood loss and incidence of deep vein thrombosis in total knee arthroplasty.

Tourniquet time and its relationship to blood loss and deep vein thrombosis were studied in 80 cases of unilateral total knee arthroplasty. These data were part of a prospective multicenter double-blind study on thromboprophylaxis for knee surgery. This study reports on the cases done at one institution in which the tourniquet was used in three different ways: group 1, no tourniquet use; group 2, limited tourniquet use for cementing time only; group 3, tourniquet use throughout the whole case. Blood loss was significantly related to tourniquet time (P = .0001). The incidence of deep vein thrombosis was not related to the tourniquet group (P = .9).

Aged↗
PubMed1995

The susceptibility of smooth implant surfaces to periimplant fibrosis and migration of polyethylene wear debris.

The purpose of this investigation was to establish whether the tissue response and migration of polyethylene debris differed at noncemented smooth and porous implant surfaces. This was accomplished through 3 separate but closely related studies: (1) a canine cylindrical implant model with smooth and porous surfaces exposed to polyethylene debris; (2) a canine total hip arthroplasty model analyzing the interface between bone and femoral implants with various porous-coating configurations; and (3) a histologic analysis of autopsy-retrieved, human, noncemented hip prostheses with noncircumferential porous coating. The cylindrical implant model involved the placement of split cylinders, 1/2 porous and 1/2 smooth, into the distal femur and proximal tibia of 4 dogs. Four control implants and 10 test implants (chronically exposed to simulated polyethylene debris with a mean size of 4.7 microns) were examined histologically as long as 30 weeks after surgery. The canine hip study involved the study of 54 noncemented hip prostheses at periods of 1, 6, and 24 months. The prostheses possessed 4 different porous surface configurations: 1 with circumferential porous coating, 2 with noncircumferential coating, and 1 without porous coating. The human retrieval analysis involved the study of 7 cadaveric femora (age, 6 months-5 years) implanted with a straight titanium-alloy prosthesis possessing proximal pads of titanium fiber metal on the anterior, posterior, and medial aspects. With all implants in all 3 studies, there was the common finding of bone ingrowth at the porous implant surface and a fibrous interface or periprosthetic cavity around the portion of the implant that was smooth surfaced. The periprosthetic cavity typically was encapsulated by a thin continuous shell of trabecular bone. In addition, polyethylene debris was found to have preferentially migrated along the smooth implant surfaces. In the longer-term canine and human hip retrievals, polyethylene particles in the micron size range were present within histiocytes, whereas larger particles as much as 100 microns were found within foreign-body giant cells. Of importance for the implants from all 3 studies, with the exception of some pronounced cavities on the lateral aspect of the human hip prostheses, the periimplant cavities around the smooth surfaces were not detectable radiographically. This study clearly established a fundamental principle of relative barriers to particulate debris migration. Smooth implant surfaces are more susceptible than porous surfaces to the development of a fibrous tissue filled periimplant cavity and the subsequent migration of polyethylene wear debris.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1994

Concerns with modularity in total hip arthroplasty.

Modularity is being diversified in total hip prostheses to increase surgical latitude in optimizing implant fixation and adjusting hip biomechanics. However, several problems have been clearly identified with implant modularity. First generation metal-backed acetabular components have shown deficiencies in the locking mechanism, the congruency and extent of polyethylene liner support, and polyethylene thickness, all of which have been implicated in accelerated polyethylene wear and failure. Evidence of screw motion against the metal backing, release of particulate material, and focal osteolysis have also been observed. At the head/neck junction evidence of corrosion and fretting has been documented with both similar-metal and mixed-metal taper combinations. Femoral prostheses with other sites of modularity present additional concerns with regard to mechanical integrity and generation of particulate debris by fretting. The modular junctions of three hip prostheses, the S-ROM, Infinity, and RMHS, were subjected to wet environment high cycle mechanical testing in a worst-case loading scenario. Preliminary results at relatively low loads up to three times body weight indicated gross stability of the modular junctions with evidence of minor fretting damage. Analysis of water solutions surrounding the modular junctions after ten to 20 million loading cycles yielded counts of one to three micron sized particles totalling several hundred thousand to several million. It is unknown what quantity of particulate material is sufficient to cause macrophage-mediated osteolysis or whether the debris from modular junctions can cause third-body wear of the articulating surfaces. Modular hip prostheses should be examined under stringent test conditions in order to characterize their fretting behavior and establish their mechanical limitations.

Biomechanical Phenomena↗
PubMed1993

Mechanical compatibility of noncemented hip prostheses with the human femur.

It is generally accepted that more flexible implants are needed to reduce stress shielding and postoperative thigh pain. However, there is no detailed information on the stiffness of currently used implants relative to the human femur. The purpose of this study was to determine the stiffness characteristics (bending, torsional, and axial) of human femora relative to commercially available prostheses as a first step in assessing the mechanical compatibility of the implants. This was achieved by computerized tomography scanning of a collection of human femora from proximal to distal at 10 mm intervals, digitizing the cross-sectional contours, and calculating the stiffness characteristics of each section using standard beam theory. The results show that significant stiffness mismatches exist, especially for larger stem sizes and for stems fabricated from cobalt-chrome alloy. Interestingly, certain implant stiffness values are lower than those of the femur for stems up to 15 mm in diameter, substantially so if the implant is made from titanium alloy and incorporates design features that reduce area and moments of inertia. The data suggest that only larger implant sizes need to be adjusted for increased flexibility compared with current stands.

Aged↗
PubMed1993

Parathyroid carcinoma: case report.

Parathyroid carcinoma is a rare entity, representing less than 1% to 5% of patients with primary hyperparathyroidism. Parathyroid carcinomas are often symptomatic, have markedly elevated calcium levels, have palpable masses, are equally distributed between the sexes, and present 10 years younger than their benign counterparts. Parathyroid carcinoma is often undiagnosed preoperatively, suspected intraoperatively, and only confirmed postoperatively. When diagnosed, the treatment of choice is an en-bloc resection of the tumor.

Aged↗
PubMed1992

Producing and avoiding stress shielding. Laboratory and clinical observations of noncemented total hip arthroplasty.

Experimental canine model studies of stiff versus flexible, fully porous-coated, metallic femoral stems (differing by three- to fivefold in stiffness characteristics) revealed markedly different resorptive bone remodeling patterns. The flexible stem resulted in about 30% more cortical bone retention adjacent to the implant at one-year postimplantation and larger differences in dogs killed two and three years after surgery. Strain-gauge studies confirmed that there are differences in cortical bone strains with the two stem designs, the flexible stem producing a more uniform and more nearly normal strain distribution medially. Differences in cortical bone remodeling were quantified using dual energy X-ray absorptiometry (DEXA). The bone mineral content in femora with the flexible stem decreased less than 20%, compared to normal. At three years postimplantation, the bone mineral content of the femora with the stiff stem was about 50% that of the femora with the flexible stem. Clinically, DEXA revealed that 5%-15% changes in bone mineral density at various periimplant sites were common within the first two years after surgery; these changes were not usually evident roentgenographically. Serial roentgenographically distinct bone resorption was usually associated with bone mineral density changes of 20%-50%. Five- to 13-year roentgenographic follow-up observations of 213 cases with the Anatomic Medullary Locking prosthesis showed that pronounced bone resorption occurred in 33% of patients. Larger stems (greater than 13 mm in diameter) and stems with extensive porous coating had a significantly higher incidence of pronounced bone resorption than smaller stems and those with proximal coating. The stiffness characteristics of the human femur were established as a function of canal size and compared with those of noncemented hip prostheses. Increased mechanical compatibility was found for stems made of titanium alloy and with design features that reduce cross-sectional area and moment of inertia. Clinical data suggest that to reduce the likelihood of pronounced bone resorption, it would be beneficial for the implant to possess a bending stiffness of about one half to one third that of the human femur.

Absorptiometry, Photon↗
PubMed1991

Porous-coated acetabular component. Quantitative assessment of normal radiophosphate uptake as a function of implant age.

A computer-assisted quantitative analysis was undertaken of normal radiophosphate bone uptake adjacent to the porous-coated acetabular component in asymptomatic patients. Implants ranged from 1.6 to 49 months of age. In 62 hips, it was found that implants newer than 12 months of age had uptakes that were significantly greater than those 12 months or older. Between 12 and 49 months, there was no correlation with age, indicating a stabilization of the remodeling process.

Acetabulum↗
PubMed1991

Quantitative analysis of radiophosphate uptakes in asymptomatic porous-coated hip endoprostheses.

A quantitative analysis of the uptake of radiophosphate adjacent to the femoral component of a porous-coated cementless prosthesis was undertaken in asymptomatic patients in order to establish normal temporal changes. The group consisted of 55 patients with 62 arthroplasties of 1.6-49-mo duration. Ratios of the stem, stem tip, greater trochanter, lesser trochanter and calcar, and normal femur to the reference sacroiliac joint were obtained, as well as tip-to-stem, and stem-to-normal femur in unilateral arthroplasties. The ratios remained stable at 12 months and beyond, except for the tip and lesser trochanter. Tip-to-stem and tip-to-sacroiliac joint ratios decreased by 24% and 33%, respectively, between 12 and 49 mo. There was also a decrease in the relative uptakes at the lesser trochanter and calcar in the same time interval. Evidence is given that different designs of prostheses may not have the same normal temporal uptakes of radiophosphate.

Adult↗
PubMed1990

The effect of stem stiffness on femoral bone resorption after canine porous-coated total hip arthroplasty.

Bilateral noncemented total hip arthroplasty (THA) was produced in dogs to determine the effect of stem stiffness on stress-related bone resorption. Two porous-coated femoral implants of substantially different stiffnesses were designed for direct comparison. One was manufactured from cobalt-chromium (CoCr) alloy, the other from titanium alloy. The titanium stem was hollowed out to a wall thickness of 1 mm to further reduce its stiffness. The cumulative stiffness differences were about 5.4-fold axially and 3.6-fold in bending and torsion. Staged bilateral THA was performed on eight dogs. Each dog received a stiff CoCr stem on one side and a flexible titanium stem on the other. After death, the femora were removed and processed for undecalcified thin-section histology. Bone ingrowth and remodeling were quantified by computer-aided image analysis and compared between stem designs. All femoral specimens showed bone ingrowth fixation of both stiff and flexible stems along the implant length. Tetracycline labeling indicated active bone turnover in the femoral cortex and in regions of ingrowth. However, gross differences in femoral bone remodeling were observed both roentgenographically and histologically. Femora with the flexible stems consistently showed much less bone resorption than those with the stiff stems. Quantitative analysis of paired cross-sections indicated an average of 25%-35% more cortical bone area in the femora with flexible stems. Severe resorption of the cortex in the midstem region occurred in three of the femora with the stiff stems but in none with the flexible stems. Stem stiffness strongly influences bone remodeling. The flexible stem results in more uniform load transfer and less stress shielding.

Animals↗
PubMed1975

Hemoperitoneum from liver cell adenoma in a patient on oral contraceptives.

A case of hemoperitoneum from ruptured benign liver cell adenoma in a young woman with a long history of oral contraceptive use is presented. The importance of recognizing the cause of this intra-abdominal emergency is stressed, and comment is made about the entity occurring in women on contraceptive drugs.

Adult↗