Non-specific immunohistochemical responses in surgical tissue collected from total joint arthroplasty

Tissues retrieved during revision arthroplasty (n = 25) were processed for routine immunohistochemical techniques to localize the presence of bone resorbing cytokines (IL-1, TNF alpha, and IL-6), and to identify areas of significant necrosis and metallic deposition. Tissues were processed and embedded according to standard laboratory techniques. Several tissue sections were prepared for each sample collected. Several sequential slides were used to demonstrate a thorough histopathological evaluation. Other slides of the same tissues were processed for immunohistochemical evaluation specifically for the localization of cytokines. To identify specific cytokine reactions, antibodies against cytokines were added in working dilutions overnight. Another set of slides were incubated overnight with nonspecific protein and served as negative controls. At the end of the incubation period, all slides were washed in buffer and a second antibody conjugated with peroxidase was added to both sets of slides for one hour. The slides were developed for peroxidase activity. The results revealed that there were several locations on the tissues that appeared highly reactive for cytokines. However, some of these areas turned out to be nonspecific when compared with negative controls and the Hematoxylin and Eosin stained slides. Areas of extreme necrosis or where metal debris was present demonstrated sites of nonspecific reactivity. Areas of necrosis have a high nonspecific affinity for antibodies and these areas of necrosis can be demonstrated on the Hematoxylin and Eosin sections, and were avoided in determining the amount of specific cellular reactivity. The results of this study strongly suggest that the aforementioned factors must be carefully controlled in determining true cellular responses that causes resorption of bone and eventually implant failure.

Morphological and biochemical modifications of human macrophages treated with various biomaterials

Although tissue culture techniques are used extensively to explore the biocompatibility of various biomaterials used in orthopaedic, dental and pharmaceutical fields, the role of these materials towards human monocytes/macrophages has not been fully elucidated. The specific objectives of this investigation were: (1) to determine the biochemical markers resulting from exposure of the human monocytes/macrophages to titanium (TI), large size polyethylene (LSP), submicron polyethylene (SPE), hydroxyapatite (HA), large particle size tricalcium phosphate (LTCP), and small particle size tricalcium phosphate (STCP), and (2) to morphologically evaluate the viability of the cells treated with the aforementioned biomaterials. Approximately 15 volunteers donated blood for each phase (24, 48, and 72 hours) of the experiment. The monocytes were isolated by following established lab procedures (Histopaque 1077 and 1119). Aseptic techniques were followed throughout each phase. Each phase contained four experimental groups (TI, LSP, SPE, HA). Each group was comprised of six wells. The total protein, catalase, LDH, MDA, and cell count were measured using established lab protocols. Data obtained suggests that: (I) regardless of the biomaterial being used all experimental groups experienced remarkable phagocytosis in the first two phases (24, 48 hours), (II) during the 24 hour phase MDA activities were increased in TI, LTCP, and STCP treated wells when compared to the control and other experimental groups, (III) in the 48 hour phase the MDA level increased in LPE and STCP treated cells, (IV) there were significant differences in LDH levels in LPE, STCP, and SPE at 24 hours compared to the control and other experimental groups, (V) LDH activities were increased in LPE, STCP, SPE, and LTCP at 48 hours, and (VI) at 72 hours there were significant increases in catalase activity in HA, TI, SPE and LPE when compared to the control group and other experimental groups. Information obtained from this study provided new ideas about the interrelationship of various biomaterials, the effect of size and cell response to the various biomaterials.

The use of estrogen, DHEA, and diosgenin in a sustained delivery setting as a novel treatment approach for osteoporosis in the ovariectomized adult rat model

It is well established that the pattern of bone loss from the cortex in osteoporotic bone begins from the endosteal surface of the cortex, where there is enlargement of the medullary canal at the expense of the inner cortex. Bone loss does not occur at the periosteal surface. The objective of the following study was to induce osteoporosis in female rats by ovariectomy, followed by treatment with sustained delivery of Diosgenin (DG), dehydroepiandrosterone (DHEA), or estrogen (E) after clinical signs of osteoporosis. Female Sprague Dawley rats were divided randomly into five groups containing four rats/group. Rats comprising group 1 were left intact and served as a control group. Animals in groups 2-5 were ovariectomized (OVX) and, after a 14 day delay to allow for induction of osteoporosis, were implanted with TCPL capsules containing DG, DHEA, and E, respectively. The experiment was ceased after 33 days of treatment, at which time the vital and reproductive organs for each group were collected, weighed, and analyzed histomorphometrically for differences. Further analysis of the progression of osteoporosis in the experimental animals was obtained by performing x-ray analysis of each group on a semi-weekly basis. By collecting and analyzing the femurs from each animal, we were also able to obtain important information about the histologic changes associated with osteoporosis (left femur), as well as data regarding the effects of osteoporosis on the mechanical strength of bone via three point bending analysis (right femur). The data generated by this study revealed important information as to the efficacy and safety of the alternative treatments DHEA, E, and DG for osteoporosis. First, histomorphometric analysis revealed that treatment with DHEA, E, and DG reduced the endosteal perimeter and cortical area to values very similar to controls (intact). Second, results of the bending stress and modulus in OVX and treated animals were not statistically different from the intact control animals, which suggests that the material properties of the bone were unaltered. Third, there is an increase in total body weight associated with OVX that is reduced to control levels after replacement therapy. Finally, OVX also resulted in reproductive tissue atrophy, which was reversed by all three of the treatment regimens in this study. These data suggest that bone loss after OVX can be significantly reduced by supplementation with sustained levels of DHEA, E, and DG without jeopardizing other body organs.

Morphometric analysis of cortical bone upon the exposure to sustained delivery of anabolic promoting agents using adult male rats as a model

Several investigations have documented that the use of anabolic agents could promote osteogenesis and enhance bone ingrowth in traumatized bone. Previously, anabolic steroids have been shown to increase the mineralization of bone. However, their clinical use has been limited because of the unwanted virilizing activity. The previous studies used systemic administration of anabolic steroids, which subjects other tissues within the body to high concentrations of hormones. In addition, different anabolic/androgenic steroids have varying affinities to different cell types within tissues. The specific objectives of this study were (i) to histopathologically evaluate the structural changes associated with sustained delivery of testosterone (T), dihydrotestosterone (DHT), and androstendione (AED) using adult male rats as a model, and (ii) to morphometrically evaluate the cortical areas and length upon the exposure of the aforementioned hormones for 90 days. A total of 23 adult rats were randomly divided into five groups (group I = control, group II = sham, group III = AED, Group IV = T and group V = DHT treated). At the end of the treatments the animals were euthanized and the x-rays, blood, and bones were analyzed using standard laboratory protocols. Data obtained from this investigation revealed the following: (A) all treated femurs appeared healthy with no traumatic responses observed in comparison to control animals, (B) measurements of the inner perimeter of the bone on the endosteal side showed significant reduction in the androgen treated animals. This suggesting that the androgens caused increases in the cortical bone. The differences seen in the amount of reduction was in the following ease: T > DHT > AED. C) quantitative measurements of the cortical length showed slight increases in the cortical lengths in the androgen treated rats in comparison to the control.

The prevention of osteoporotic progression by means of steroid loaded TCPL drug delivery systems

Numerous studies have suggested that there is a link between the age-related decreases in Estradiol and adrenal androgens, and the subsequent development of senile osteoporosis. The specific objectives of this investigation were: 1) to deliver Dehydroepiandrosterone (DHEA), Diosgenin (DG), and Estradiol (E) at sustained levels by Tri-Calcium Phosphate Lysine drug delivery systems (TCPL), and 2) to study the effects of the sustained delivery of DHEA, DG, and E on the bone turnover of adult female rats following withdrawal of the endogenous hormonal milieu by means of ovariectomization (OVX). In this study, 20 female Sprague-Dawley rats were randomly divided into five groups containing four rats per group. The rats in Group 1 served as intact controls. Animals in groups 2-5 were ovariectomized, and groups 3-5 were implanted immediately with TCPL drug delivery capsules containing DHEA, DG, and E, respectively. Group 2 served as the SHAM (OVX only) group. At the end of 33 days post implantation, the vital organs, reproductive organs, and femurs were collected and evaluated. Bone histomorphometric analyses as well as mechanical strength testing was performed. Data obtained from this study demonstrated that body weights were increased in all OVX animals, and that E replacement resulted in body weights that were not significantly different from intact controls. No differences were seen in the wet weights of any vital organs. However, a decrease in the weights of the cervix and oviducts were evident in all ovariectomized groups, with the exception of the E group. Thirty-three days following OVX, the OVX-only group exhibited an increased inner medullary area, decreased thickness of the cortical layer of bone, and decreased mechanical strength. The group treated with DHEA and the group treated with E were shown to maintain both the medullary area and the cortical thickness (as compared to the intact control group). The three point bending test of the femora showed that OVX-only induced a slight decline in mechanical strength, and that DHEA and DG, but not E, showed increases in mechanical strength. Results of this experiment suggest that DHEA and E may reduce bone remodeling as evidenced by the reduction in the medullary area, and that DHEA may possibly be used in postmenopausal patients to reduce osteoporotic progression.

TCPL drug delivery system: the effects of synthetic DHEA and Diosgenin using an ovariectomized rat model

Dehydroepiandrosterone (DHEA) has been shown in numerous studies to exhibit a host of benefits at the vital and reproductive organ levels. However, the use of naturally occurring DHEA is hindered by its inability to survive the first-pass metabolic process of the liver. One possible alternative means that deserves consideration is the administration of DHEA's precursor, namely, Diosgenin (DG). The specific objectives of this investigation were: 1) to deliver DHEA and DG at sustained levels by Tri-Calcium Phosphate Lysine (TCPL) drug delivery systems using ovariectomized (OVX) adult rats as a model, and 2) to evaluate the biochemical and histopathological changes associated with the sustained delivery of DHEA and DG. A total of 30 adult female rats were used in this investigation. The animals were further divided into 8 groups. Groups 1 and 2 animals served as intact control groups while each rat in groups 3-8 was ovariectomized (sham (33), n = 3 [group 3], sham (47), n = 4 [group 4]). Groups 5 and 6 were implanted with DHEA (group 5) and DG (group 6) loaded TCPL capsules immediately following the OVX procedure. Groups 7 and 8 were implanted with DHEA (group 7) and DG (group 8) loaded capsules 14 days following OVX. Surgical aseptic technique was employed according to standard laboratory protocols. Maliondialdehyde (MDA) and hormonal levels were measured from serum, collected semi-weekly, during the entire investigation (for 47 days) and X-rays were performed weekly. Pap smears were collected daily for 47 days to assess endometrial changes associated with DHEA and DG treatment. Following sacrifice (at day 33 for groups 1, 3, 5, and 6 and at day 47 for groups 2, 4, 7, and 8), routine H and E staining was conducted for histopathological evaluation of the reproductive and vital organs. Results of this investigation demonstrated: 1) OVX resulted in an increase in total body weight, and the use of DHEA and DG returned the body weight to near normal levels as compared to the intact control groups, 2) TCPL capsules delivered DHEA and DG at a sustained level during the 47 day study, 3) serum levels of MDA are as follows: DG > DHEA = OVX > control for the 33 day phase and OVX > DG > DHEA > control for the 47 day phase, 4) no significant changes were observed in total wet weights, as well as the morphology of the spleen, kidney, adrenal, heart, liver, and lung tissues, 5) OVX resulted in an atrophy and non-keratinization trend in the reproductive tissues, and sustained delivery of DHEA and DG showed no remarkable change in these tissues, 6) the use of sustained delivery of DHEA and DG resulted in higher weights of uteri compared to the OVX group. In conclusion, this study provided more information regarding the interrelationship between DHEA and DG, and the physiological responses encountered when they are administered continuously using the adult OVX rat as a model.

The role of the route of administration of poly-chlorinated biphenyls (PCBs) on the reproductive and vital organs of adult female rats

Studies have shown that high doses of Polychlorinated biphenyls (PCBs) given by conventional methods (orally or injections) have adverse effects on the reproductive and vital organs of adult female rats. However, there has not been documentation as to the effects of PCBs on adult female rats by means of a sustained delivery system. The specific objectives of this study were: (1) to investigate the effects of sustained delivery (TCPL ceramics) of PCB versus conventional mode of administration (injection) on the reproductive and vital organs of the adult female rat, (2) to evaluate the role that PCB that might have on the estrus events of adult female rats upon the exposure by sustained delivery (TCPL ceramics) and conventional mode (injection), and (3) to histopathologically evaluate the effect that PCB might have on the ovarian and accessory organs upon the sustained delivery for 21 days. A total of 10 adult female rats (BW 270-300 gm) were randomly divided into three groups. Group 1 (n = 3) served as the control, group 2 (n = 4) was injected intramuscularly every other day with Aroclor 1254 (0.1 cc), and each rat in-group 3 (n = 3) was implanted with TCPL capsules (5 mg of 2,3,3',4,5-Pentachlorobiphenyl). Aseptic surgical techniques were performed throughout the experiment. Blood (1 cc) was collected biweekly for biochemical analysis, and body weights were recorded as well. Pap smears were taken daily at approximately the same time for 25 days, and two slides were made for each pap taken (1 pap stain, 1 Diff Quik). At the end of 21 days post-implantation, all control and experimental animals were sacrificed following standard lab procedures (overdose of Halothane). The reproductive and vital organs were collected, weighed, fixed, embedded, sectioned, and stained (H&E) for histological evaluations. Data obtained from this investigation suggest the following: (1) TCPL devices were able to deliver PCB at sustained levels for 21 days, (2) regardless of the route of PCB administration no significant change was observed in total body weight compared to the controls, (3) conventional administration of PCB resulted in a remarkable changes in the fallopian tubes compared to control and sustained delivery implanted animals, (4) there were no obvious change was observed in the phases of estrus cycles upon the exposure of PCB, and (4) histopathological evaluation of spleen, kidneys, heart, adrenals, ovaries, uterus, and cervix tissues exposed to PCB did not reveal any significant changes compared to the intact group.

Cellular responses to various levels of sustained delivery of testosterone in the ventral prostate

The objective of this study was to evaluate the effect of various dosages of testosterone (T) delivered in a sustained manner by means of tricalcium phosphate-lysine (TCPL) delivery system on morphological changes of prostatic tissue using adult male rats as a model. In this experiment, adult male rats (250-300 g BW) were randomly divided into five equal groups (n = 8). Rats in group I, II, and III were castrated and implanted subcutaneously with TCPL loaded with three different dosages (10, 100 and 200 mg T, respectively) of T. Rats in group IV were castrated and implanted with sharm TCPL capsules, and rats in group V served as intact unimplanted controls. Surgical aseptic techniques were performed according to standard laboratory procedures. At the end of 4 and 12 weeks post implantation, four animals from each group were sacrificed and the prostate tissues were collected, weighted, and embedded for histo-pathological evaluations. Data collected from this study have shown that exogenous intake of T delivered in a sustained manner for twelve weeks induced several pathophysiological conditions in ventral prostatic tissue in comparison to the control and sham operated groups. This phenomenon was found to be directly proportional to the dose or the level of sustained delivery. The results demonstrated that the use of 10 mg filled TCPL implants decreased the total mass weight of ventral prostate. Light microscopic evaluation of this group (Group I) revealed a cellular adaptation through an atrophy in the epithelium component. Cytopathological observations such as low cuboidal and thin glands, pleomorphism, and occasional presence of connective tissue stroma were detected. In contrast, ventral prostate collected from animals implanted with TCPL filled with 200 mg T (Group III) showed a significant increase in weights of the wet prostatic tissues in comparison to all groups. Histopathological evaluations demonstrated the following. (i) prostatic hypertrophy alone, or in conjunction with hyperplasia of the epithelial cells, (ii) less connective tissue stroma in comparison to the control group, (iii) occasional involvement of mitotic figures, and (iv) increased angiogenesis. No significant change was observed in those animals implanted with TCPL capsules containing 100 mg T compared to the intact control animals.

Fibrous capsule formation in response to ultrahigh molecular weight polyethylene treated with peptides that influence adhesion

A wide variety of hard tissue substitute materials for reconstruction have been designed for use in dental and orthopaedic procedures. Most of the literature provides information on the osteocompatibility of these materials, and not on soft tissue compatibility. The bone bonding strength of the materials is relatively high, but there seems to be a lack of bonding properties with soft tissue which results in the formation of fibrous encapsulation. This lack of soft tissue bonding can lead to implant failure. Therefore in order to study how artificial materials may remain in the body for long periods of time and remain functional, it is vital to understand the fibrous tissue encapsulation process. Ultrahigh molecular weight polyethylene coated with RGD, RGE, Poly-L-Lysine, or saline was implanted into Sprague Dawley rats either intraperitoneally or subcutaneously for 12 weeks. Aseptic surgical techniques were followed according to standard laboratory procedures. Blood was collected weekly for the first 8 weeks and at 12 weeks, and analyzed for lactate dehydrogenase activity to assess muscle wasting and compatibility. Lactate dehydrogenase activity was elevated at weeks one and two for groups implanted with materials, in comparison to control unoperated animals. From weeks 3-12, the LDH activity was similar in all groups indicating that there was no adverse response to the implanted material. The implants were harvested at the end of 12 weeks, and the fibrous capsule was screened histologically to determine thickness and cell types at the interface. The results clearly showed that the implants that were placed subcutaneously had a less extensive fibrous and vascular tissue formation, than those implanted intraperitoneally. The results also indicated that the location of the implant intraperitoneally, determined the extent of the fibrous tissue formation. The implanted materials coated with RGD and Poly-L-Lysine had thicker fibrous capsule formation than RGE coated implanted at both the subcutaneous and intraperitoneal sites. The results also suggest that the implant-interface contained fewer inflammatory cells when the implants were placed subcutaneously. The overall results indicate that more than surface charge or coating govern the formation of fibrous tissue in vivo.

Interaction of cells with UHMWPE impregnated with the bioactive peptides RGD, RGE or Poly-L-lysine

Several reports have suggested that encapsulation of orthopaedic and dental implants with fibrous tissue can lead to implant failure. The binding of cells to the surface of the implants is specific to amino-acid sequences, typically RGD. The specific objective of this study was to investigate the interaction of cultured human peripheral macrophages with specific amino-acid sequences to determine if adherence is due to the specificity of such sequence. Macrophages were seeded at a density of 1 x 10(5) cells on ultra high molecular weight polyethylene (UHMWPE) coated with either amino-acid heteropolymers of RGE, RGD, or amino-acid homopolymer Poly-L-Lysine. Cells were observed daily and morphology was recorded. The results showed that cells growing in the presence of RGD had significantly (p < 0.05) higher numbers of cells adhering and remaining viable, in comparison to cells growing on Poly-L-lysine or RGE. Cells growing on UHMWPE coated with RGE appeared irregularly (elongated and spindle) shaped and unevenly spaced. The cells growing in the presence of Poly-L-Lysine showed cellular disruption and lysis, whereas cells growing on the RGD appeared intact, regularly spaced and began fusing into giant cells. Lactate dehydrogenase activity was used as a measure of membrane integrity, and cells grown on UHMWPE coated with Poly-L-lysine showed a two-fold increase in activity over control and peptide treated groups. Immunochemical analysis for cytokine (IL-1) release as a measure of cellular reactivity revealed an increase level in the experimental groups after 24 hours and remained measurable over the duration of the experiment. Cells incubated on uncoated polyethylene showed no evidence of increased cytokine response. Overall, the results show macrophages can interact with specific coating on the material surface, and these surfaces can affect the adhesion process adherence. Use of RGE, which inhibits binding of the cells, may be a factor that can be used to coat implants to increase their longevity.

Comparison of alveolar bone loss, alveolar bone density and second metacarpal bone density, salivary and gingival crevicular fluid interleukin-6 concentrations in healthy premenopausal and postmenopausal women on estrogen therapy

BACKGROUND

Osteoporosis is an age-related metabolic bone disease characterized by decreased mass and increased susceptibility to fracture. The literature suggests a relationship between oral bone loss and skeletal osteoporosis; however, most studies have produced conflicting results. The purpose of this study was to determine if a relationship exists among alveolar bone loss, alveolar bone density, second metacarpal density, salivary and gingival crevicular fluid interleukin 6 (IL-6), and IL-8 concentrations in premenopausal and postmenopausal healthy women receiving estrogen therapy.

METHODS

Twenty-eight healthy women (aged 23-78) were evaluated for this study. A vertical bitewing and hand radiographs were taken, and the subjects were evaluated for the presence of active periodontitis. The bitewing and hand radiographs were digitized, and measurements were made from the cemento-enamel junction to the alveolar crest from both arches. Bone density was evaluated in the maxillary and mandibular alveolar process and at the mid-shaft of the second metacarpal. Percent cortical area and the moment of inertia measurements were also determined. Stimulated whole saliva was collected for a 5-min period using a cube of paraffin as a stimulant and was analyzed for total protein by a colorimetric reaction and IL-6 and IL-8 by ELISA.

RESULTS

The results of the study showed that postmenopausal women on estrogen therapy had more alveolar bone loss, more missing teeth, and reduced alveolar and second metacarpal bone density than premenopausal women. In addition, postmenopausal women on estrogen therapy had higher salivary IL-6 concentrations than premenopausal women. Alveolar bone densities were also strongly correlated to second metacarpal densities.

CONCLUSIONS

The results of the study suggest that changes in alveolar bone density and levels of bone resorptive cytokines in saliva may be secondary to changes in menopausal status. These changes may predispose loss of alveolar bone with resultant loss of teeth.

Failure of the porous-coated anatomic prosthesis in total knee arthroplasty due to severe polyethylene wear

Four hundred and eighty-seven total knee arthroplasties were performed by a single surgeon with use of a porous-coated anatomic prosthesis between 1982 and 1989. There were thirty-two clinical failures (7 per cent) due to severe wear of the surfaces of the tibial and patellar polyethylene components. Thirty patients had a revision. The average time to failure of the implant was four and one-half years. The initial clinical symptoms of failure by wear consisted of a painless effusion with a decreased range of motion. Subsequent pain was considered as the criterion for failure necessitating operative intervention. Increased weight and decreased age of the patient and a thinner tibial component were significant predictors of an increased risk of failure (p < 0.01). Examination of retrieved tibial components revealed extensive delamination caused by fracture of the polyethylene at a depth of about one millimeter below the surface. Cracks that had propagated in from the medial and lateral peripheries of the tibial component toward the center of the condyles were also a common finding. It appears that the design of the implant as well as clinical factors (the age and weight of the patient) contributed to the mechanical failure of the polyethylene of these implants.

Failure mechanisms of metal-backed patellar components

A specific type of failure of a metal-backed patella occurred, consisting of a separation of the polyethylene from the metal backing. This dissociation is followed by wearing of the metal backing against the femoral component. This produces clinical signs and symptoms that usually require revision. This failure occurred in 16 knees of 14 patients. Average time to failure was 14 months. Failure was associated with patellar implant design, surgical technique, patient characteristics, and femoral component design. The plastic of the metal-backed patellae was thin at the periphery. The metal plate did not extend to the edge of the plastic and acted like a sharp edge that cut the thin plastic. The plastic dome was not bonded to the plate and became separated from the plate once the plastic tore. The plate became deformed. Failure was more likely with a subluxated, tilted, or excessively thick patella or flexed femoral component. The typical patient was a large, active male who had achieved more than 115 degrees of flexion. A prominent edge on the lateral intercondylar ridge of the femoral component resulted in a concentrated load being applied to the plastic dome and favored rapid wear of the patella. Until a greater understanding of patello-femoral loading is acquired, caution in the use of metal-backed patellae is recommended.