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PubMed2003

Crosslinking of biological tissues using genipin and/or carbodiimide.

The study was to investigate the crosslinking characteristics, mechanical properties, and resistance against enzymatic degradation of biological tissues after fixation with genipin (a naturally occurring crosslinking agent) and/or carbodiimide. Fresh tissue was used as a control. It was found that both genipin and carbodiimide are effective crosslinking agents for tissue fixation and genipin crosslinking is comparatively slower than carbodiimide crosslinking. Additionally, tissue fixation in genipin and/or carbodiimide may produce distinct crosslinking structures. Carbodiimide may form intrahelical and interhelical crosslinks within or between tropocollagen molecules, whereas genipin may further introduce intermicrofibrillar crosslinks between adjacent collagen microfibrils. The stability (denaturation temperature and resistance against enzymatic degradation) of the fixed tissue is mainly determined by its intrahelical and interhelical crosslinks. In contrast, intermicrofibrillar crosslinks significantly affect the mechanical properties (tissue shrinkage during fixation, tensile strength, strain at break, and ruptured pattern) of the fixed tissue. Moreover, the degree of enzymatic degradation of the fixed tissue may be influenced by three factors: the availability, to the enzyme, of recognizable cleavage sites, the degree of crosslinking, and the extent of helical integrity of tropocollagen molecules in tissue.

Animals↗
PubMed1992

Comparative evaluation of fresh, fixed, and cryopreserved solid tumor cells for reliable flow cytometry of DNA and tumor associated antigen.

Five different protocols for the short-term preservation of cells used for multiparameter flow cytometric assay of tumour associated antigens (TAA) and DNA were assessed in cell suspensions prepared by mechanical disaggregation of 15 gynecological tumors. The protocols at 4 degrees C were 1) storage in buffer, 2) storage in 50% methanol, and 3) storage in buffer after formalin fixation. Tissues were also cryopreserved as cell suspensions and tissue blocks. When the TAA expression and DNA histograms of the preserved cells were compared with those in fresh cell suspensions, cryopreservation was found to be the best method: TAA expression was well preserved and there was a good correlation between TAA expression and the quality of the DNA histograms, respectively, in fresh and cryopreserved cells (RS: 0.82-0.91, P less than 0.001 for all TAAs). The cell suspensions preserved at 4 degrees C all showed a significant increase in background fluorescence (P less than 0.05) and a reduction in the TAA specific fluorescence (P less than 0.011). Methanol fixation was better than buffered formalin for the proteins studied, though both gave significantly worse results than cryopreservation. The quality of these cell suspensions and the correlation with TAA measurements in fresh cell suspensions deteriorated progressively with time, particularly if they were stored more than a week.

Antigens, Neoplasm↗
PubMed1995

Intravascular ultrasound can be used to evaluate pulsed laser ablation of arterial tissue.

BACKGROUND AND OBJECTIVE: Intravascular ultrasound (IVUS) has been used successfully to detect intravascular lesions. This study evaluates the ability of IVUS to detect acoustic damage to the arterial wall following high power, pulsed laser ablation. STUDY DESIGN/MATERIALS AND METHODS: Arterial ablation and disruption were performed in necropsy bovine aorta with a Ho:YAG laser using energy ranging from 140-720 mJ/pulse at 5 Hz. Laser energy was delivered with 2 mm diameter, multifiber over-the-wire catheters. A 20-MHz IVUS catheter was used to image the arterial damage prior to tissue fixation and morphometry. RESULTS: IVUS images revealed ablation craters surrounded by high acoustically backscattering zones. By histology, the arteries revealed ablation craters lined with thermal coagulation surrounded by a region of dissection and vacuolization. The depth and width of the highly backscattering zones on IVUS images correlated strongly with the corresponding morphometric measurements of tissue dissection (r = 0.92, P = 0.0001 and r = 0.80, P = 0.0001, respectively). Morphometric measurements of the ablation crater depth correlated strongly with laser energy (r = 0.90, P = 0.0001), whereas crater width was not correlated with laser energy (r = 0.27, P = 0.09). CONCLUSION: This study demonstrates that IVUS can detect and measure the extent of arterial damage following pulsed laser ablation. This may provide a means of detecting the extent of tissue disruption and help develop approaches to reduce or prevent extensive tissue damage.

Angioplasty↗
PubMed1997

[Variations in mesenchymal cell activity between rheumatic and non-rheumatic valve disease].

Deoxyribonucleic acid (DNA) synthesis of mesenchymal cells in the diseased valve tissue of patients with rheumatic and non-rheumatic valve diseases were compared. Surgically resected mitral valves from eight rheumatic and eight non-rheumatic patients in their 40s were examined immunohistochemically to estimate the activity of the various mesenchymal cells by cell cycle analysis, using monoclonal antibodies to cyclin E, A, B1, p53, and b cl-2 after routine tissue fixation, paraffin embedding and sectioning. Cyclin B1-positive fibrocytes and fibroblasts of the spongiosa and fibrosa were observed in all non-rheumatic cases, whereas some lymphocytes in the perivascular area were cyclin B1-, p53- and b cl-2-positive in rheumatic cases. The distinct qualitative difference in the mesenchymal cells of valve tissue between rheumatic and non-rheumatic etiologies suggests a different mode of valve pathology.

Adult↗
PubMed1992

Electron-dense tracer evidence for a blood-brain barrier in the cuttlefish Sepia officinalis.

Electron-dense tracers were used to study the permeability of the blood-brain interface in a cephalopod mollusc, the cuttlefish Sepia officinalis. Gel filtration established that horseradish peroxidase is a suitable tracer for in vivo injection, but microperoxidase is not, being subject to binding by plasma proteins. Perfusion-fixed brain vertical and optic lobes showed no endogenous peroxidatic activity. Horseradish peroxidase was injected intravenously, and allowed to circulate for 10-35 min before tissue fixation by immersion or perfusion. Horseradish peroxidase reaction product was undetectable in the bulk of the brain parenchyma. In microvessels, venous vessels and at the brain surface, horseradish peroxidase penetrated the layers of endothelial and pericyte cells, being stopped by the layer of perivascular glia. In arterial vessels, tracer restriction occurred at the level of the pericytes. In the region of tracer blockade, a gradient of tracer could be traced in the intercellular cleft, from high at the luminal end to undetectable at the tissue end. The clefts of the restricting zone were generally wide (15-20 nm), with faint periodicities or linking structures spanning the cleft, and contained a fibrillar extracellular material. Perfusion of lanthanum chloride in saline for 15 min, followed by precipitation of lanthanum phosphate during fixation, resulted in lanthanum tracer distribution similar to that of horseradish peroxidase. Horseradish peroxidase was seen filling extracellular spaces within the neuropile when the blood-brain barrier was breached by a stab wound, indicating that the interstitium itself does not restrict tracer diffusion. It is concluded that Sepia has a blood-brain barrier tight to horseradish peroxidase and ionic lanthanum. The restricting junction is not a typical zonula occludens or septate junction, but appears to reduce tracer penetration by a filtering mechanism within the extracellular cleft. The barrier is formed by perivascular glial cell processes in the microvessels and venous vessels, but by pericytes in arterial vessels. This organization suggests that a glial blood-brain barrier may be the primitive condition, and a barrier associated with vascular elements (endothelium/pericyte) a later development.

Animals↗
PubMed1992

Fc-mediated nonspecific staining of the porcine brain with rabbit antisera in immunocytochemistry is prevented by pre-incubation of the sera with proteins A and G.

Nonspecific staining was detected in immunocytochemical procedures on the porcine hypothalamus with rabbit antisera, irrespective of the antigen specificity of the sera, in magnocellular neurons of the paraventricular (PVN) and supraoptic nuclei (SON), and in the vasopressin- and oxytocin-containing nucleus (VON). The present study was designed to test the hypothesis that this staining is mediated by the Fc portion of rabbit immunoglobulins. Rabbit antisera against neuropeptides localized predominantly outside the PVN, SON, and VON were employed in combination with different detection methods. The intensity of the nonspecific staining varied depending on the antiserum and persisted after pre-absorption of the antisera with their homologous peptides. Nonspecific staining and antigen-specific staining were differentially affected by the method of tissue fixation. The nonspecific staining could be prevented by preincubation of the antisera with proteins A and G, which left the antigen-specific staining intact, whereas additional preabsorption with homologous peptide abolished all staining. These observations suggest that the Fc region of IgGs is indeed involved in the nonspecific staining. On press-blots of homogenates from SON tissue subjected to isoelectric focusing, one band in the low-pH region was found with all antisera. Pre-incubation of the antisera with protein A abolished the staining of this band but did not affect staining of antigen-specific bands. Pre-incubation with proteins A and G is proposed as a routine control to check for nonspecific staining mediated by the Fc region of IgGs in immunocytochemical procedures, particularly those that employ rabbit sera in porcine brain.

Animals↗
PubMed2003

Revision anterior cruciate ligament reconstruction using autografts with a polyester fixation device.

Twenty-nine patients who had undergone anterior cruciate ligament (ACL) revision were evaluated retrospectively between 1992 and 2000. A similar surgical technique was used in all cases. Twenty-six patients underwent revision following failed primary and revision surgery with the ABC scaffold ligament. There were 2 failed primary semitendinosus/gracilis (STG) autografts and one failed bone patella tendon bone (BPTB) autograft. Autologous hamstring tendons (STG) were used in 26 knees, quadriceps tendon in 2 and BPTB autograft in 1 knee. The Mark I Soffix soft tissue fixation device was used in 16 patients and 13 patients underwent reconstruction with the Mark II BH (Button Hole ) Soffix. Follow up evaluation included clinical examination, KT 2000 arthrometric side to side difference (SSD) assessment, Lysholm, Tegner and IKDC scoring. The average follow up time was 50+/-22 months. The overall SSD was 1.66+/-1.5 mm, a mean Lysholm score of 87.2+/-12.5 was obtained and 22 patients had an IKDC score of nearly normal (B). In the Mark II (BH Soffix) group knees were significantly tighter than in the Mark I Soffix group (P<0.05) with a mean SSD of 1.23+/-1.3 and 2.0+/-1.6 mm, respectively. However there were no significant differences in the other measured parameters between the two fixation devices. Multiply re-operated knees tended to have lower IKDC and Lysholm scores (not statistically significant). We concluded that the technique reported in this study can restore stability to the knee following failed primary or revision ACL reconstruction and the results in the non-multiply operated knees are comparable to primary reconstruction.

Adult↗
PubMed1988

Antigen localization in immunoperoxidase-stained plastic-embedded soft tissues.

Immunoperoxidase stains were performed on normal and neoplastic tissue from prostate, colon, thyroid, lung, nerve, uterus, and placenta embedded in both plastic (glycolmethacrylate [GMA]) and paraffin. Positive results in plastic section were obtained for carcinoembryonic antigen (CEA), keratin, epithelial membrane antigen (EMA), thyroglobulins, S-100, prostate-specific antigen, human chorionic gonadotrophin (HCG), and beta-HCG. More delicate staining with more precise localization of antigens is noted. Superior (paraformaldehyde) fixation and cold processing followed by GMA polymerization (4 degrees C) allow for optimum antigen survival. After fixation, tissue processing involves a series of 0.1 mol/L phosphate buffer rinses with sucrose and ammonium chloride in a conventional dip-and-dunk processor placed in a 4 degrees C cold room. Acetone dehydrations are used before GMA infiltration, cold polymerization, and sectioning. Before immunoperoxidase staining, the plastic section is digested in .25% bovine trypsin for ten minutes. The immunoperoxidase methods described can be useful when small biopsies are routinely embedded in plastic to obtain improved histologic (hematoxylin-eosin) sections. There may also be research applications in quantifying antigen expression in benign, dysplastic, and neoplastic tissues by examining the stains under high power.

Adenocarcinoma↗
PubMed1986

Three phase bone scanning as an aid to early diagnosis in reflex sympathetic dystrophy of the hand. A study of eighty-nine cases.

In reflex sympathetic dystrophy, three phase radionuclide bone scanning with Tc-99m methylene diphosphonate is preferred. The first phase corresponds to the dynamic behavior of the tracer. After appropriate data processing (by Fourier's analysis), three functional images may be obtained. The second phase corresponds to the tissues fixation of the tracer 5 to 10 minutes after the injection. Based on the results of 89 cases of post-traumatic or postsurgical reflex sympathetic dystrophy observed in 128 patients investigated with this method, diagnostic sensitivity was 96%, while specificity was 86%. The scintigraphic patterns observed during the 100 week period after the initial trauma demonstrate the precocity and the significance of circulatory and tissues phenomena as well as their variations according to treatment. The scintigraphic criteria of regression or stabilization of disease are discussed.

Adolescent↗
PubMed2001

Proliferation of masseter myocytes after distraction osteogenesis of the porcine mandible.

PURPOSE: Long-term success of distraction osteogenesis depends on the ability of the surrounding soft tissues to tolerate distraction forces and to adapt to the resulting increase in skeletal length and volume. The hypothesis tested in this study was that mandibular elongation by distraction induces myocyte proliferation. MATERIALS AND METHODS: Unilateral mandibular angle osteotomies were performed in 16 Yucatan minipigs. The hemimandibles were lengthened using semiburied distraction devices (Synthes Maxillofacial, Paoli, PA) with 0-day latency, 1, 2, or 4 mm/d distraction rates, and a neutral fixation period of twice the gap size in days. In 2 additional animals, the dissection and osteotomies were performed, and distraction devices were placed without activation (sham control). At the end of neutral fixation, tissues were taken from masseter muscle overlying the osteotomy and the equivalent region on the unoperated side (contralateral control). Proliferation of myocytes was estimated using immunohistochemical localization with antibodies against proliferating cell nuclear antigen (PCNA). RESULTS: Muscle overlying the distracted mandible showed 6-fold more PCNA-positive myocytes (16.8% +/- 11.3%) than the contralateral control side (2.8% +/- 1.1%, P < .0001). In the 2 sham-control animals, there was a low index of PCNA-positive myocytes on both the osteotomy (2%, 5%) and the contralateral sides (1%, 2%). CONCLUSIONS: The results of this study suggest that distraction of the porcine mandible by the protocol described induces myocyte proliferation in the masseter muscle. A proliferative response may contribute to improved long-term stability of mandibular expansion by distraction osteogenesis.

Animals↗
PubMed2002

Graft selection in anterior cruciate ligament reconstruction.

Selecting the appropriate graft for ACL reconstruction depends on numerous factors including surgeon philosophy and experience, tissue availability (affected by anatomical anomalies or prior injury or surgery), and patient activity level and desires. Although the patella tendon autograft has the widest experience in the literature, and is probably the most commonly used graft source, this must be tempered with the higher reported incidences of potential morbidity and pitfalls associated with its use. The hamstring tendons are gaining increasing popularity, mostly due to reduced harvest morbidity and improved soft tissue fixation techniques, and many recent studies in the literature report equal results to BTB ACL reconstruction with respect to functional outcome and patient satisfaction. On the other hand, many of these studies report higher degrees of instrument (KT-100) tested laxity for hamstring reconstruction, and some have reported lower returns to preinjury levels of activity. One question that remains to be addressed is how closely objectively measured laxity tests correlate with subjectively assessed outcomes and ability to return to high levels of competitive sports. Allograft use, which decreased in popularity during the 1990s, appears to be undergoing a resurgence, with better sterilization processes and new graft sources (tibialis tendons), leading to increased availability and improved fixation techniques. The benefits of decreased surgical morbidity and easier rehabilitation must be weighed against the potential for greater failure of biologic incorporation, infection, and possibly slower return to activities. In our practice, for high-demand individuals (those playing cutting, pivoting, or jumping sports and skiing) BTB tends to be the graft of choice. For lower demand or older individuals, hamstring reconstructions will be performed. Allograft tissue will be used in older individuals (generally over 45 years old), those with signs of arthritis (and compelling evidence of instability), or those individuals who understand the pros and cons of allograft use fully and do not want their own tissue used.

Anterior Cruciate Ligament Injuries↗
PubMedDate not supplied

In vitro evaluation of screws and suture anchors in metaphyseal bone of the canine tibia.

OBJECTIVE: To compare ease of insertion, load to failure, and mode of failure of cortical and cancellous screws, BoneBiter, IMEX, and TwinFix suture anchors in canine metaphyseal tibial bone. STUDY DESIGN: Experimental biomechanical study. ANIMALS: Canine cadaveric tibias. METHODS: One investigator inserted all anchors and subjectively evaluated ease of placement. Anchor systems were loaded to failure along axis of insertion with audio-video recording to determine failure mode. RESULTS: BoneBiter was the most difficult anchor to insert successfully. Mean+/-SD loads to failure were cancellous screw (711+/-193 N), IMEX 4.7 mm 18 g wire (661+/-163 N), IMEX 4.0 mm 18 g wire (661+/-165 N), cortical screw (635+/-184 N), BoneBiter #5 Kevlar suture (393+/- 109 N), and TwinFix 5.0 mm #2 polyester (267+/-73 N). No significant differences were noted among the cortical screw, cancellous screw, IMEX 4.7 and 4.0 mm, all of which were significantly (P<.001) greater than BoneBiter and TwinFix . Failure modes were pullout of bone, suture-wire breakage, eyelet breakage, or no failure to 1000 N: screws (18,0,0,2), IMEX (18,1,1,0), BoneBiter (2,8,0,0), and TwinFix (0,10,0,0). CONCLUSIONS: Fixation devices were user friendly, with the exception of BoneBiter. Mode of failure is dependent on suture material and anchor design. Cortical and cancellous screws, and IMEX anchors with 18 g wire have significantly greater load to failure compared with BoneBiter and TwinFix suture anchors. CLINICAL RELEVANCE: Based on load to failure, ease of use, design characteristics, and cost, IMEX anchors may have advantages over other comparable soft tissue fixation devices.

Animals↗
PubMed2000

Effects of double cross-linking technique on the enzymatic degradation and calcification of bovine pericardia.

The strength, resorption rates, and biocompatibility of collagenous biomaterials are profoundly influenced by the method of cross-linking. The in vitro and in vivo calcification and enzymatic degradation of bovine pericardia (BP) after a series of surface modifications were studied as a function of exposure time. Collagenase degradations of modified BP were monitored by scanning electron microscopy and tensile strength measurements. Bovine pericardium was modified by a combination of different tissue fixatives such as glutaraldehyde (GA), carbodiimide (EDC), diisocyanate (HMDIC), and polyethylene glycol (PEG). GA-PEG-EDC-PEG and GA-PEG-HMDIC-PEG combination treated BP retained maximum stability in collagenase digestion compared to GATBP. In vitro calcification studies and in vivo rat subcutaneous implantations of modified pericardium have shown substantial reduction in the calcification of double cross-linked BP with PEG modification. Further, the biocompatibility aspects of pericardial tissues were established by platelet adhesion and octane contact angle. It seems that cross-links involving amino and carboxyl residues may provide new ways of controlling biodegradation and calcification.

Animals↗
PubMed2000

Effect of amniotic fluid cellular content on attic aeration pathways: histologic observations of infants aged 2 to 4 months.

HYPOTHESIS: The tissue-fixed amniotic fluid cellular content (AFCC) in the middle ear and mastoid antrum causes foreign body type reactions that may later severely restrict the aeration pathways to the main attic and to Prussak's space. BACKGROUND: It was shown by Aschoff 100 years ago that AFCC remained in the neonate ears and caused sterile otitis media. Recent data show that children born through thick meconium are at risk for large quantities of AFCC entering the middle ear cleft, the ensuing inflammatory reaction being related to the amount of AFCC. Spread of AFCC in the neonate occurred along the aeration pathways with corresponding tissue fixation but further systematic data in young infants are lacking. METHODS: Five temporal bones of three infants aged 2 to 4 months were embedded in celloidin, serially sectioned at 20 microns, and every 10th section stained with Hematoxylin and eosin and mounted on slides. All slides were studied and relevant details of aeration pathways and all compartments photographed. RESULTS: The histologic changes were characterized by the development of masses of pseudocystic granulation tissue, with some remnants of the original AFCC, mainly in the form of fragments of hair. The tympanic isthmus was involved to varying extent, maximally to half of its size. Posterior tympanum and the stapes region had masses of fresh granulation tissue, the maturing of which might cause marked indrawing of the posterior pars tensa and further reduction of the tympanic isthmus. Aeration of Prussak's space was severely involved in two bones, favored by the narrow pathway through the posterior pouch. Features of recent acute or secretory otitis media were associated with the early changes caused by AFCC. CONCLUSIONS: The granulation tissue in this age group is immature and its final fate is decided by the nature of the future ear disease. If the AFCC contamination is slight, the granulation tissue after maturing may appear only in the form of thin cords and sheets, a frequent chance finding in ear surgery. Large amount of AFCC may lead to chronic inflammation, which may predispose the child to recurring middle ear infections during infancy. Further histologic and clinical studies in older infants and young children are needed to find out the final outcome after a massive AFCC contamination of the new-born middle ear.

Amniotic Fluid↗
PubMed1990

Ultrastructural aspects of preeclampsia. II. Mitochondrial changes.

Biopsy specimens were obtained under direct vision at the time of cesarean section from 47 patients (35 with preeclampsia and 12 normotensive patients) and from four women with cesarean section hysterectomies (all normotensive) as an extension of previous work. Tissues were obtained from the myometrium near the placental bed and from the opposite side of the uterus. Skin biopsies were also obtained from eight women with preeclampsia and liver biopsies were obtained from two patients with acute microvesicular fatty change of pregnancy (one with and one without concomitant preeclampsia). Specimens were examined histologically and by electron microscopy. Mitochondrial changes in small vessels, principally venules, in myometrial smooth muscle, myometrial interstitial cells, circulating leukocytes, epidermal and dermal cells, and hepatocytes were examined and compared between women with preeclamptic and normotensive pregnancies. These findings were then compared with mitochondria from 500 biopsies over the same 3-year interval to assess the possible role of delay in tissue fixation. There were 12 other biopsies from nonpregnant women of childbearing age. As further control on artifact, other specimens were initially sampled immediately in the operating room and then serially for up to 2 hours later. Artifact as a basis for the mitochondrial changes was ruled out by these procedures. Normal mitochondria undergo a morphologic conformational sequence with physiologic changes in substrate, oxygen consumption, adenosine diphosphate, and respiratory rate. The mitochondria of preeclamptic tissues show a central disruption that is outside this normal sequence or cycle. This disruption occurs more often and is more severe in preeclampsia than in normotensive pregnancies. In addition, the hypertrophic smooth muscle of the pregnant uterus has a complex of cytoplasmic organelles in a paranuclear location, usually apical, that contains a variable mixture of glycogen, the Golgi apparatus, endoplasmic reticulum, mitochondria, and small unidentified microvesicles. This complex has the location and appearance suggestive of a myometrial "power pack" of significance in metabolism and contraction. The presence of similar mitochondrial changes in a limited sample of nonuterine tissues is suggestive of a systemic metabolic disorder as an important feature of preeclampsia.

Cell Survival↗
PubMed1998

Pseudolipomatosis cutis: superficial dermal vacuoles resembling fatty infiltration of the skin.

Empty spaces within the dermis of paraffin-embedded sections of skin have been attributed to fatty infiltration and postulated to originate from topical steroid administration or sebaceous gland rupture. We examined skin biopsy specimens exhibiting dermal vacuolation to determine whether this phenomenon was associated with specific skin diseases and to attempt to illuminate its etiology. Routine hematoxylin-eosin-stained sections from 26 formalin-fixed, paraffin-embedded biopsy specimens were examined. Histochemical stains for mucin and immunohistochemical staining for S100 protein and vascular markers were performed. Dermal vacuolation was characterized by empty spaces, 15-120 microm in diameter, in the superficial dermis, associated with either fibrosis/sclerosis or a lymphocytic infiltrate. There was no relationship to clinical findings, topical steroid treatment, or histologic diagnosis. There was no evidence of true adipocyte differentiation, and vascular markers were negative. Transmission electron microscopy showed nonmembrane-bound irregular spaces in the dermis. Dermal vacuoles likely represent an artifact of tissue fixation or processing and are unrelated to the underlying pathologic process. We propose the name pseudolipomatosis cutis, analogous to insufflation-induced colonic vacuolation, to distinguish this phenomenon from true dermal fatty infiltration and to emphasize its incidental, likely artifactual nature.

Adipocytes↗
PubMed1988

Fibrin sealant in orthopedic surgery.

The use of clotting substances from blood for hemostasis dates back to 1909. In 1972, modern fibrin sealing (FS) was developed in Vienna. For application, the two components, i.e., a sealer protein solution (mainly fibrinogen) and a thrombin solution, are mixed to produce the fibrin clot. The sealant may be applied with a needle, as a spray, or by premixing (e.g., with antibiotics, bone chips) for subsequent sealant application in cavities. While the positive effect of FS in normal wound healing has been conclusively demonstrated, its influence on bone healing remains controversial. The positive experimental results mostly refer to the early phase of bone healing in rabbits (cortical drill hole, autologous and heterologous (Kiel) cancellous transplants, osteotomies, osteochondral fractures) and dogs (cortical bone and spongiosa defects). Some authors observed no effects (in dogs, osteotomy) or delayed healing in artificial bone growth chambers with the use of heterologous sealant. FS was also applied in combination with implantation material (tricalcium phosphate and bone gelatin) to facilitate application. Clinical results are especially convincing as to osteochondral fractures, repair of the Achilles tendon, and in hemophiliacs. Fibrin sealant facilitates hemostasis, permits tissue fixation, enhances plasticity of granular implant material, and stimulates fibroblast growth. Although its direct osteogenic effect remains questionable, fibrin sealant is known to be an excellent tool in orthopedic and trauma surgery.

Animals↗
PubMed1992

Tissue ingrowth into titanium and hydroxyapatite-coated implants during stable and unstable mechanical conditions.

Lack of initial mechanical stability of cementless prostheses may be responsible for fibrous tissue fixation of prosthetic components to bone. To study the influence of micromovements on bony ingrowth into titanium alloy (Ti) and hydroxyapatite (HA)-coated implants, a loaded unstable device producing movements of 500 microns during each gait cycle was developed. Mechanically stable implants served as controls. The implants were inserted into the weight-bearing regions of all four femoral condyles in each of seven mature dogs. Histological analysis after 4 weeks of implantation showed a fibrous tissue membrane surrounding both Ti and HA-coated implants subjected to micromovements, whereas variable amounts of bony ingrowth were obtained in mechanically stable implants. The pushout test showed that the shear strength of unstable Ti and HA implants was significantly reduced as compared with the corresponding mechanically stable implants (p less than 0.01). However, shear strength values of unstable HA-coated implants were significantly greater than those of unstable Ti implants (p less than 0.01) and comparable to those of stable Ti implants. The greatest shear strength was obtained with stable HA-coated implants, which was threefold stronger as compared with the stable Ti implants (p less than 0.001). Quantitative determination of bony ingrowth agreed with the mechanical test except for the stronger anchorage of unstable HA implants as compared with unstable Ti implants, where no difference in bony ingrowth was found. Unstable HA-coated implants were surrounded by a fibrous membrane containing islands of fibrocartilage with higher collagen concentration, whereas fibrous connective tissue with lower collagen concentration was predominant around unstable Ti implants. In conclusion, micromovements between bone and implant inhibited bony ingrowth and led to the development of a fibrous membrane. The presence of fibrocartilage and a higher collagen concentration in the fibrous membrane may be responsible for the increased shear strength of unstable HA implants. Mechanically stable implants with HA coating had the strongest anchorage and the greatest amount of bony ingrowth.

Analysis of Variance↗