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PubMed2001

Comparison of the biomechanics and histology of two soft-tissue fixators composed of bioabsorbable copolymers.

The purpose of this study was to assess the dynamic in vitro and in vivo characteristics of two different bioabsorbable copolymer soft-tissue fixation devices and to determine their efficacy in reattaching soft tissue to bone. Suretac fixators (Smith & Nephew/Acufex MicroSurgical Inc., Northwood, MA), made of polyglyconate (2:1 glycolic acid:trimethylene carbonate), and Pop Rivets (Arthrotek, Warsaw, IN), made of LactoSorb (82% poly L-lactic acid, 18% polyglycolic acid), were anchored into synthetic bone, and their pull-out strengths were evaluated. The devices were also evaluated with the use of an in vivo goat model in which the medial collateral ligament (MCL) was elevated from the tibia and directly reattached. In the in vitro biomechanical study, the Suretac fixators had negligible strength remaining by four weeks, whereas the Pop Rivets retained 50% of their strength at 4 weeks, 20% at 8 weeks, and negligible strength at 12 weeks. The in vivo strength of MCL repairs affected by each implant was not statistically different at any of the time points. Histologically, both implants were absorbed by 52 weeks, and there was no appreciable adverse tissue response. In conclusion, both copolymer fixators were found to be biocompatible. The Pop Rivet fixators demonstrated in vivo performance comparable to the Suretac fixators, although the Pop Rivets retained strength longer in vitro. Our results suggest that both devices provide adequate strength of fixation before degrading to allow the healing soft tissues to reach or surpass their native strength.

Absorption↗
PubMed1975

Quantitative studies of the renal corpuscles iii: the influence of post mortem delay before taking renal tissue samples and of the duration of tissue fixation.

Comparative quantitative studies of glomeruli in biopsies of the guenon monkey kidney were made to give a numerical measure of the effect of varying periods of fixation of the biopsy tissue in Carnoy's fluid (1-2-24 hrs.), and of the effect of progressive post mortem delay before renal tissue samples were taken (2-4-6-12 hrs.). Additional aims were to determine possible quantitative differences between subcapsular, intermediate and juxtamedullary glomeruli, and to determine whether the glomerular area should be determined with reference to the inner aspect of Bowman's capsule (total area) or to tangents laid at the top of the capillary loops (corrected total area). The quantitative methods used were total and differential counts of glomerular nuclei by light microscopy and point counting for determination of glomerular and mesangial areas. Statistical evaluation was made by a two-way analysis of variance. The differential counts of nuclei were not affected by duration of fixation, nor by post mortem delay up to 12 hrs. before tissue samples were taken. The mesangial area expressed as a percentage of total area was significantly lower two hours post mortem, while total nuclear concentration was significantly lower at time 0 and two hours post mortem than at four, six and 12 hours post mortem. Total nuclear concentration increased as duration of fixation was increased, probably a reflection of tissue shrinking. Differences in nuclear concentration were also noted at different levels of the renal cortex. These differences were only apparent when the glomerular area was determined with reference to the inner aspect of Bowman's capsule, and disappeared when the corrected total area was used. It is concluded that duration of tissue fixation and post mortem delay before tissue samples were taken both affect method sensitivity, as reflected by some, not all, of the parameters measured. The numerical differences in the parameters were not large, however, and it will be the specific study which will determine whether variable fixation times and post mortem delay in obtaining tissue samples is acceptable. As most renal biopsies contain both subcapsular and juxtamedullary glomeruli there is probably no advantage in using the corrected glomerular area instead of the total glomerular area limited by Bowman's capsule.

Animals↗
PubMed2006

Primer: tissue fixation and preservation for optimal molecular analysis of urologic tissues.

Appreciation of the different methods of tissue handling is a prerequisite to obtaining accurate and biologically relevant tissue-based information. When a tissue sample is removed from its environment, biological changes are induced within its constituent cell population. It is inevitable that artefacts will be induced through obtaining and processing tissues, irrespective of whether the samples comprise a few cells derived by fine-needle aspiration or larger specimens obtained surgically. Depending upon the level of sophistication of the analytical methods subsequently employed, such changes might be irrelevant, or might result in acquisition of spurious data. While even brief ischemia alters expression of some genes, detectable by appropriate molecular techniques, the same changes might make no appreciable difference to tissue histomorphology. Furthermore, the phenotype of viable cells is known to change during tissue collection and handling. For example, transitional epithelial cells voided in urine are not phenotypically identical to those retained within the urothelium. Such phenotypic changes are temporary and might be of little consequence to subsequent analyses. Surprisingly, many cells in tissues preserved in an ischemic state can remain viable for several hours, and are believed to remain genotypically stable in the short term.

Alcohols↗
PubMed2005

Tissue Fixation System posterior sling for repair of uterine/vault prolapse -- a preliminary report.

AIMS: To assess the posterior Tissue Fixation System (TFS) sling for repair of uterine/vault prolapse. PATIENTS AND METHODS: The TFS comprises of two small polypropylene soft tissue anchors connected to an adjustable polypropylene tape. The posterior TFS sling works much like a McCall procedure. The anchors are inserted just lateral to the uterosacral ligaments. Tightening the sling elevates the prolapsed uterus/vaginal vault. The study group comprised 67 patients who were assessed with a 24-h urinary diary, structured questionnaire, transperineal ultrasound, urodynamics, cough stress test, and 24-h pad test, pre and postoperatively. RESULTS: Sixty-seven patients, mean age 65 years (35-87), mean weight 71 kg (38-117 kg), mean 1.6 previous pelvic operations, underwent posterior sling (level 1) repair for uterine/vault prolapse (fourth degree: n = 2; third degree: n = 17; second degree: n = 20; symptomatic first degree: n = 28). Level 2 (n = 18) and level 3 repairs (n = 18) were also performed as required. One patient was lost to the study. At mean 9 months' review (3-15 months), the prolapse repair had been successful in all but one patient. There were however, 14 de novo herniations postoperatively (20%), cystocoele 12, enterocoele 1, rectocoele 1. Operating time for the sling only was 5-10 min, and mean hospital stay was 1.5 days. Minimal analgesia was required. CONCLUSIONS: The preliminary results indicate that the TFS posterior sling appears to work well in patients with uterine/vault prolapse. Longer term follow up and studies by other surgeons are required to fully evaluate this procedure.

Adult↗
PubMed2005

Soft tissue fixation in the face with the use of a micro mitek anchor.

An alternative method for fixation of soft tissue in the face, such as the medial and lateral canthus and free flaps, and for reconstruction of the nasolabial fold is presented, using the micro Mitek Anchor. The insertion of a bone anchor requires only a limited dissection, and the point of insertion can be determined accurately. These advantages are obvious when performing a canthoplasty. Using the bone anchor to fixate a free flap to the facial skeleton is an effective way to prevent sagging of the flap as a result of gravitational forces. In contrast, the use of bone anchors in facial neurofibromatosis has not been as rewarding.

Eyelids↗
PubMed2005

Midurethral Tissue Fixation System sling -- a 'micromethod' for cure of stress incontinence -- preliminary report.

AIMS: To assess the effectiveness of the Tissue Fixation System (TFS) in patients with stress incontinence. The TFS uses two small plastic anchors to fix an (adjustable) midurethral polypropylene mesh sling into the soft tissues below the pubic bone. PATIENTS AND METHODS: Thirty-six patients with stress incontinence, mean age 55 (35-87), mean weight 76 kg (33-117 kg), mean 0.8 previous operations for stress incontinence, underwent a TFS midurethral sling operation. The patients were preoperatively assessed with a structured questionnaire, 24-h urinary diary, cough stress test, transperineal ultrasound, and urodynamics. Using the TFS delivery system, a midurethral mesh tape was attached to the fibromuscular tissues behind the perineal membrane. The suburethral vaginal fascia was also tightened. Post-operatively. the patients were reviewed at 6 weeks, and at 3-monthly intervals with ultrasound, and cough stress tests. RESULTS: Primary symptomatic cure rate at mean 9 months (3-15 months) was 83.4% (n = 36). Pad test loss decreased from a mean 12.7 g to a mean of 0.2 g; mean operating time was 5 min, and mean hospital stay was 24 h (12-48 h). There were no cases of obstructed micturition, and minimal analgesia only was required postoperatively. CONCLUSION: The TFS is a promising new method. The results at this stage are similar to those achieved previously with the 'tension-free' tape operations, but with greater safety and shorter operating time. Testing by other surgeons will be required to evaluate this method further.

Adult↗
PubMed1998

Lack of histological cerebellar changes in Wistar rats given pulegone for 28 days. Comparison of immersion and perfusion tissue fixation.

Pulegone was given orally by gavage to groups of 28 SPF Wistar rats at dosage levels of 0 or 160 mg/kg body weight per day for 28 days. Clinically treated animals showed slackness, depression, decreased food consumption, and body weight. The loss of body weight was accompanied by a marked decrease in plasma creatinine. In contrast to earlier results, this study did not reveal occurrence of cyst-like spaces in the white matter of cerebellum using either perfusion or immersion tissue fixation techniques. Pulegone increased plasma alkaline phosphatase and relative liver weight indicating an adverse effect on the liver.

Animals↗
PubMed1976

Studies in vivo on the effects of parathyroid hormone upon kidney cyclic adenosine 3',5'-monophosphate content using rapid tissue fixation by microwave irradiation.

Microwave irradiation is shown to be a useful method for simultaneously killing chicks and fixing tissues. Renal adenylate cyclase and phosphodiesterase activities were rapidly abolished by microwaving. The increase in chick kidney cyclic adenosine 3',5'-monophosphate (cyclic AMP) content produced by intravenous bovine parathyroid hormone (PTH) injection was much greater in microwaved birds than in those killed by cervical dislocation with subsequent tissue fixation in liquid nitrogen. After PTH injection there was a prolonged elevation of renal cyclic AMP content. At the time of maximum response (2 minutes), log. dose-response curves were linear in the dose range 0.1-10 U. The responses to three different bovine PTH preparations were indistinguishable. Arginine vasopressin, arginine vasotocin, salmon calcitonin and prostaglandin E1 did not affect kidney cyclic AMP content within 2 minutes. Because of its specificity and precision, the method is of use for the in vivo bioassay of PTH. Injection of CaCl2 (20 mumoles) 1 minute before, or conjointly with, bovine PTH inhibited the subsequent increase in kidney cyclic AMP content. The synthetic bovine PTH peptide fragments BPTH (1-34) and BPTH (2-34) both increased chick kidney cyclic AMP content. The use of such fragments allows investigation of the structural requirements of PTH for interaction with the systems regulating cyclic AMP metabolism in the kidney in vivo.

Animals↗
PubMed1978

Tissue fixation and staining with osmium tetroxide: the role of phenolic compounds.

It has been postulated that phenol-containing areas of plant and animal tissues were osmiophilic, but proof of direct interaction between osmium tetroxide and phenolic materials, or the nature of such reactions, has been lacking. We find that, under conditions similar to those of normal tissue fixation, osmium tetroxide reacts rapidly with those phenols containing o-dihydroxy groups (including such species found in plant tissues) to give very stable chelate complexes. We conclude that these complexes are responsible for the observed electron-density in phenol-containing areas of tissue treated with osmium tetroxide, so that such phenols are indeed osmiophilic.

Histocytochemistry↗
PubMed1988

Carbodiimide as a tissue fixative in histamine immunohistochemistry and its application in developmental neurobiology.

The object of this study was to develop an immunohistochemical method that could be used to study neuronal histamine, especially in nerve fibers and terminals where most previous methods have not been applicable. Three new antisera were produced in rabbits against conjugated histamine, and the fixative used in conjugation, 1-ethyl-3(3-diamethylaminopropyl)-carbodiimide (EDCDI), was used in tissue fixation and compared to paraformaldehyde. Specificity of the antisera was established with dot-blot tests on nitrocellulose, with blocking controls and affinity-purified antibodies. EDCDI appeared to be superior to paraformaldehyde as a fixative, and histamine-immunoreactive nerve cells were visualized in developing rat brain during late fetal development from embryonal day 12. By the second postnatal week, the distribution of histamine-immunoreactive neurons in rat brain had reached the adult pattern and immunoreactive nerve fibers were seen in many areas. Posterior hypothalamic neurons from newborn rat in vitro showed strong immunoreactivity for histamine and developed long varicose fibers, which covered the culture dish by the end of the fourth week in vitro. Fixation with EDCDI also allowed detection of histamine in gastric enterochromaffin-like cells and mast cells in rat. The results suggest that the histamine-containing neuron system in rat brain develops during the late fetal and early postnatal periods, and that immunoreactive neurons develop long fibers both in vivo and in vitro.

Animals↗
PubMed2005

Interinstitutional variability and effect of tissue fixative on the interpretation of a Barrett cytokeratin 7/20 immunoreactivity pattern in Barrett esophagus.

A unique pattern of cytokeratin (CK) 7/20 immunostaining (diffuse staining with CK7 and surface and superficial crypt staining with CK20) has been reported to be useful in differentiating Barrett esophagus (BE) from intestinal metaplasia of the stomach. However, there are conflicting results regarding the prevalence of a BE CK7/20 staining pattern in BE between different studies. Therefore, this study was performed to determine the degree of variability in interpretation of a BE CK7/20 pattern and to determine the reasons for variability when present. Esophageal and gastric mucosal biopsies from 67 patients with BE and antral intestinal metaplasia at 2 institutions were immunostained for CK7/20. All cases were evaluated for the presence of a BE CK7/20 pattern by 2 gastrointestinal pathologists from each institution, and the degree of agreement between institutions was determined. To determine the effect of tissue fixation and staining methods on the pattern of CK7/20 staining, unstained slides were exchanged between institutions, stained separately by each institution, and reexamined by all pathologists. There was excellent agreement on the presence of a BE CK7/20 staining pattern between pathologists at the same institution but only moderate agreement between pathologists at different institutions (71% overall, kappa = 0.58). Among BE cases, a BE CK7/20 staining pattern was identified in 50 (96%) of 52 cases by Cleveland Clinic Foundation pathologists but only 35 (67%) of 52 cases by Brigham and Women's Hospital pathologists. The major source of disagreement related to the interpretation of weak or variable CK7 staining of deep intestinalized mucosa in BE biopsies that were fixed in Hollande, but not those that were fixed in formalin. After the creation of a new set of criteria for a positive BE CK7/20 staining pattern, which took into account the effects of Hollande's fixative, the degree of agreement between pathologists at each of the 2 institutions was excellent (100%, kappa value = 1.0). Therefore, the CK7/20 staining pattern is influenced by the type of fixative used. Only a moderate level of interobserver agreement among pathologists regarding a BE CK7/20 pattern can be achieved if one is not aware of these effects. Nevertheless, specific criteria for interpretation of CK7/20 staining can be successfully applied between institutions and need to be developed before use of this technique in clinical practice.

Barrett Esophagus↗
PubMed2001

Design and evaluation of a cryogenic soft tissue fixation device -- load tolerances and thermal aspects.

Mechanical studies of soft connective tissues often encounter methodological difficulties, particularly in the secure fixation of the tissues. A simple, inexpensive technique which allowed stable cryofixation of soft tissues in uniaxial loading machines was developed. The cryogenic fixation device was evaluated in terms of its fixation strength and the temperature gradients within the tested tissues. Human patellar ligaments and quadriceps tendons were tested successfully to an average failure load of 2219N (S.D. 448N) with mid-substance failures occurring in 90% of the specimens. The temperature gradients within porcine flexor and extensor tendons were determined and found to exhibit a typical diffusion profile. The fixation quality was dependent upon the initial block temperature and the desired testing time. In summary, the cryofixation device presented here is an effective tool for soft tissue fixation but the effect of this type of fixation on internal tissue temperatures and possible testing times must be acknowledged.

Adult↗
PubMed1996

Tissue fixation security in transosseous rotator cuff repairs: a mechanical comparison of simple versus mattress sutures.

The primary purpose of this investigation was to compare tissue fixation security by simple sutures versus mattress sutures in transosseous rotator cuff repair. These two repair techniques were each performed in 17 human cadaver shoulders, with two bone tunnels being used for the repair by two simple sutures and two other bone tunnels being used for the repair by one mattress suture. The repairs were loaded to failure in a servohydraulic materials test system. Rotator cuff repair by simple sutures was found to be significantly stronger than repair by mattress sutures (P = .0007). The average ultimate load to failure for the simple suture construct (189.62 N) was 39.72% greater than that for the mattress suture construct (135.71 N). Most of the failures occurred by suture breakage at the knot. Load-sharing by multiple suture tails and multiple knots in the simple suture configuration likely contributed to its superior strength characteristics compared with the mattress suture configuration.

Biomechanical Phenomena↗
PubMed1978

Lysozyme antigenicity and tissue fixation.

The preservation of lysozyme (LZM) antigenicity was studied in paraffin embedded tissue blocks. The reactivity for LZM varied with the type of tissue studied, the fixative used, the osmolarity and pH of the fixative, fixation time and temperature, and the method of dehydration. In both rat and human tissues aqueous fixatives were superior to nonaqueous fixatives in retaining LZM antigenicity. Brief fixation in fixatives of low osmolarity enhanced LZM staining in the parenchymatous tissues but diminished staining in human cartilage; prolonged fixation in fixatives of high osmolarity gave opposite results. Least affected by fixation was the LZM antigenicity in the serous cells of the glands of the respiratory tract. These cells also stained most intensely for LZM of all autopsy material studied.

Animals↗
PubMed2006

The Tissue Fixation System provides a new structural method for cystocoele repair: a preliminary report.

BACKGROUND: A new reconstruction principle that uses tensioned tapes instead of large mesh is described for cystocoele repair. AIM: To apply this method to patients with central, paravaginal and cervical ring defects. METHODS: Ninety patients, mean age 63 years (29-83) and mean weight 73 kg (52-117 kg), underwent cystocoele repair using the Tissue Fixation System (TFS). Tapes were applied as a retro-obturator U-sling (n=29), transversely between both arcus tendineus fascia pelvis (ATFP) ligaments (n=45), along the path of the cardinal ligament in patients with cervical ring defects (n=12), and longitudinally along the ATFP ligament (n=4). RESULTS: At mean eight months review (three to 15 months), two failures were reported. There was one haematoma that drained spontaneously at seven days, and there were no erosions. Mean hospital stay was one a half days for the Australian group (one to seven days) and five days (four to eight days) for the European group. After using single U-sling, one patient required intermittent catheterisation for seven days before she could pass urine freely. In one patient the bladder was perforated during dissection laterally towards the ATFP; the perforation was successfully repaired. CONCLUSIONS: The tensioned tape operation is simple and accurate, and appears to work well in the short term. Longer-term studies are required.

Adult↗
PubMed2006

Modified Prusik knot versus whipstitch technique for soft tissue fixation in anterior cruciate ligament reconstruction: a biomechanical analysis.

Appropriate graft tension and secure graft incorporation in bone tunnels are essential for successful anterior cruciate ligament (ACL) reconstruction using hamstring tendon autografts. Permanent viscoplastic elongation in response to cyclic loading in the early postoperative period and the interposition of suture material in the tendon-bone interface might negatively affect graft function and rigid graft incorporation in the bone tunnels. A modified Prusik knot is an alternative option to the commonly used whipstitch technique for soft tissue fixation in ACL reconstruction. This is a controlled laboratory study. Sixteen formalin-fixed human cadaver semitendinosus tendons were armed with a modified Prusik knot or a whipstitch and tested in a load-to-failure test with a constant displacement rate of 1 mm/s, 14 in the cyclic loading test with 100 cycles from 10 to 50 N followed by 100 cycles from 10 to 75 N. The modified Prusik knot showed smaller force-induced displacements and higher stiffness of the entire construct in the load-to-failure test. Smaller preconditioning displacements were the only significant differences in the cyclic loading test. The modified Prusik knot has equal or superior mechanical properties and provides a larger area in the tendon-bone interface without suture material compared with the whipstitch technique.

Anterior Cruciate Ligament↗
PubMed1992

Laminin immunohistochemistry in brain is dependent on method of tissue fixation.

Normal adult and lesioned rat and mouse brains were fixed by formaldehyde perfusion by two methods that differ primarily in the length of the post-fixation period. Sections were subsequently immunostained using monoclonal and polyclonal antibodies to laminin. With relatively short post-fixation periods (up to 4 h), vascular basement membrane (BM)-laminin was immunostained, but intraneuronal laminin-like immunoreactivity was faint. With longer post-fixation periods (18-24 h), intraneuronal laminin-like immunoreactivity was distinct, while vascular BM-laminin immunoreactivity was reduced drastically. These findings are particularly relevant to studies examining laminin immunoreactive blood vessels in response to lesions, especially ischemic stroke. In fact, the present results suggest that the apparent neovascularization or up-regulation of vascular BM-laminin following CNS injury likely relates to differences in regional tissue fixation.

Animals↗
PubMed1998

Loop security as a determinant of tissue fixation security.

Secure arthroscopic repair of rotator cuff tears and Bankart lesions requires tight knots (knot security). Equally important, but usually overlooked, is the tightness of the suture loop (loop security). This study compared loop security in knots tied with No. 1 PDS suture using three different methods: (1) hand-tied, (2) single-hole standard knot pusher, and (3) cannulated double-diameter knot pusher. The results of this study show that the double-diameter knot pusher maintained tight suture loops that were equivalent in circumference to hand-tied loops and were significantly tighter than suture loops tied with a standard single-hole knot pusher. This study highlights the fact that loop security is equally important to knot security in tissue fixation.

Arthroscopy↗