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At least 919 records · Page 51Linked to original sources
PubMed2005

Electron paramagnetic resonance analyses of surface radical chemistries of gamma-sterilized orthopedic materials: implications pointing to cytotoxicity via wear debris-induced inflammation.

In this research, electron paramagnetic resonance (EPR) spin-trapping was utilized to determine if surface radical chemistries occur for gamma (gamma)-sterilized orthopedic materials-ultra-high molecular weight polyethylene (UHMWPE) and the novel, hybrid, diurethane dimethacrylate (DUDMA)-based RHAKOSS. The materials' ability to competitively chelate catalytic ferrous ions (Fe(2+)) or readily reduce ferric ions (Fe(3+)), and hydrogen peroxide (H(2)O(2)) directly, in facilitating the Fenton reaction (FR), is indicative of cytotoxicity. Validations with a radical scavenger aids to confirm a radical mechanism. In conjunction, materials were thermally annealed and characterized by attenuated total reflectance-Fourier-transform infrared (ATR-FTIR) spectroscopy in order to explore accelerated oxidative degradation induced by residual radicals evolving from gamma-sterilization. Particularly, there was a significant decrease in spin-adduct peak areas obtained from the reduction of H(2)O(2) in the presence of RHAKOSS or UHMWPE, evaluated against their respective controls. Additionally, chelated Fe(2+) accelerated the rate of FR. This phenomenon suggests that the materials are not better chelators than the Fe-activating chelator, edta. Neither material had the propensity to readily reduce Fe(3+) to the relevant Fe(2+), as certified by a nonradical mechanism. Alternatively, the false spin-adduct signal acquired when chelated Fe(3+) is employed arises via the nucleophilic addition of water onto the DMPO spin trap. Residual radicals in UHMWPE did not recombine/terminate following thermal annealing in an inert atmosphere. The radicals in RHAKOSS, however, did recombine under mild heating in an oxidizing or inert atmosphere. Both materials displayed quenching of ( )OH; however, for UHMWPE, this mechanism was jointly accountable for its accelerated degradation, evidenced by ATR-FTIR. Quenching of ( )OH by the silica found in RHAKOSS manifested in a competing effect that counterbalanced the observed FR. Implanted RHAKOSS is not likely to promote cytotoxicity and should not degrade, but the damaging effect of gamma sterilization on UHMWPE is a serious dilemma confronting its long-term durability and biocompatibility.

Biocompatible Materials↗
PubMed2005

Micro/nanoscale mechanical and tribological characterization of SiC for orthopedic applications.

Micro/nanomechanical and tribological characterization of SiC has been carried out. For comparison, measurements on SiC, CoCrMo, Ti-6Al-4V, and stainless steel have also been made. Hardness and elastic modulus of these materials were measured by nanoindentation using a nanoindenter. The nanoindentation impressions were imaged using an atomic force microscope (AFM). Scratch, friction, and wear properties were measured using an accelerated microtribometer. Scratch and wear damages were studied using a scanning electron microscope (SEM). It is found that SiC exhibits higher hardness, elastic modulus, scratch resistance as well as lower friction with fewer and smaller debris particles compared to other materials. These results show that SiC possesses superior mechanical and tribological properties that make it an ideal material for use in orthopedic and other biomedical applications.

Biocompatible Materials↗
PubMed2005

Evaluation of different scaffolds for BMP-2 genetic orthopedic tissue engineering.

To better understand the effects of scaffold materials for bone morphogenetic protein 2 (BMP-2) genetic tissue engineering in vivo, several gels, including alginate, collagen, agarose, hyaluronate, fibrin, or Pluronic, were mixed with adenovirus-mediated human BMP-2 gene (Adv-hBMP-2) transduced bone marrow stromal cells (BMSCs) and injected into the muscles of athymic mice to evaluate the resulting osteogenesis and chondrogenesis. These gel and gene-transduced BMSC mixtures were also loaded onto beta-TCP/HAP biphasic calcined bone (BCB) and observed under scanning electron microscopy (SEM). In addition, these composite scaffolds were implanted into the subcutaneous site of athymic mice to construct tissue-engineered bone. After injection, collagen, hyaluronate, or alginate gel mixed with gene-transduced BMSCs induced more bone formation than a cell suspension in alpha-MEM. The agarose-gene-transduced BMSC gel was found to contain much more hyaline cartilage. SEM showed the BMSCs could survive in alginate, agarose, and collagen gel in vitro for up to 8 d. After implantation of tissue-engineered bone, the alginate, collagen, and agarose gel could promote new bone formation within a BCB in vivo. Little or no bone formed after injection of fibrin or Pluronic gel mixed with BMSCs or implantation with BCB. These findings help to elucidate the effects of various scaffold materials for future research in orthopedic tissue engineering using BMP-2 transduced cells.

Adenoviridae↗
PubMed2002

Acute thrombotic thrombocytopenic purpura following orthopedic surgery.

Release of unusually large von Willibrand factor (UL vWF) multimers and a deficiency of vWF metalloprotease may result in thrombotic thrombocytopenic purpura (TTP), a life threatening disease. Surgery has been associated with TTP, probably by releasing massive amounts of UL vWF. An association between TTP and orthopedic surgery has never been reported in the literature. We report a case of TTP following a total knee replacement surgery in which prior use of ticlopidine might have played a role.

Female↗
PubMed1986

Malignant neoplasms associated with orthopedic implant materials in rats.

The carcinogenic potential of 22 orthopedic prosthetic materials was studied by implantation in bone in Sprague-Dawley rats and evaluated by complete autopsy examination performed at the time of death or at the end of the 30 month experimental period. When the number of malignancies in these rats was compared with control and sham-operated animals, a small increase in sarcomata was observed in animals bearing metal alloy implants containing high contents of cobalt, chromium, or nickel. An increased incidence of lymphomata with bone involvement was also observed in rats bearing metal implants when compared with control and sham-operated animals.

Animals↗
PubMed1999

An "openable," high-strength gradient set for orthopedic MRI.

A novel three-axis gradient set and RF resonator for orthopedic MRI has been designed and constructed. The set is openable and may be wrapped around injured joints. The design methodology used was the minimization of magnetic field spherical harmonics by simulated annealing. Splitting of the longitudinal coil presents the major design challenge to a fully openable gradient set and in order to efficiently design such coils, we have developed a new fast algorithm for determining the magnetic field spherical harmonics generated by an arc of multiturn wire. The algorithm allows a realistic impression of the effect of split longitudinal designs. A prototype set was constructed based on the new designs and tested in a 2-T clinical research system. The set generated 12 mT/m/A with a linear region of 12 cm and a switching time of 100 micros, conforming closely with theoretical predictions. Preliminary images from the set are presented.

Algorithms↗
PubMed1982

Use of prophylactic antibiotics in orthopedic surgery.

The use of prophylactic antibiotics was studied prospectively in 2371 consecutive clean orthopedic operations. The infection rates for operations with obvious selection for antibiotic prophylaxis were twice as high (7.2%) as compared with operations with planned prophylaxis (3.4%) and with operations without such prophylaxis (3.7%). Sixteen per cent of all clean operations received antibiotics for prophylaxis and 85 per cent of all prophylactic courses lasted at least 8 days or longer. Fifty-one per cent of all antimicrobial drugs used during the study were administered for prophylaxis in clean orthopaedic operations. The length of the hospital stay was the only factor closely related to the length of antibiotic prophylaxis. The drugs most often used for prophylaxis were penicillinase-resistent penicillins. Significant increase of gram-negative pathogens was observed in cultures from wounds of patients on antibiotic prophylaxis.

Humans↗
PubMed1989

Flucloxacillin compared with cefazolin in short-term prophylaxis for clean orthopedic surgery.

Two-hundred and fifty-two patients were included in a prospective, randomized, double-blind trial comparing the efficacy of flucloxacillin with that of cefazolin for clean orthopedic surgery. The preventive antibiotic regimen consisted of three 1-g injections perioperatively. There were 126 patients in each group, and the follow-up period was at least 6 months. Two deep (1.6%) and five superficial (4.0%) infections occurred in the flucloxacillin group. Three deep (2.4%) and five superficial (4.0%) infections developed in the cefazolin group.

Adolescent↗
PubMed1990

Impact of the presence of orthopedic hardware on technical performance of major amputations.

Metallic prostheses used for joint reconstruction or open reduction of fractures were discovered pre- or intraoperatively during the performance of six above-knee amputations. The prosthesis was found fortuitously before surgery in two cases on the basis of a surgical scar or radiograph of the leg. In four patients, discovery occurred intraoperatively, with adverse impact on the procedure in two cases: more proximal amputation level to allow hip nail removal was necessary in one case, and difficult transection of the prosthesis stem was encountered in one case. Orthopedic prostheses will be found with an increasing incidence in the population undergoing major amputation. As preparation for amputation, a careful review of the patient's history, a search for scars over the leg and hip, and survey radiographs of the leg must be obtained to prevent a surgical mishap caused by accidental discovery of a prosthesis.

Amputation, Surgical↗
PubMed1992

Orthopedic prosthesis fixation.

The fixation of orthopedic implants has been one of the most difficult and challenging problems. The fixation can be achieved via: (a) direct mechanical fixation using screws, pins, wires, etc.; (b) passive or interference mechanical fixation where the implants are allowed to move or merely positioned onto the tissue surfaces; (c) bone cement fixation which is actually a grouting material; (d) biological fixation by allowing tissues to grow into the interstices of pores or textured surfaces of implants; (e) direct chemical bonding between implant and tissues; or (f) any combination of the above techniques. This article is concerned with various fixation techniques including the potential use of electrical, pulsed electromagnetic field, chemical stimulation using calcium phosphates for the enhancement of tissue ingrowth, direct bonding with bone by glass-ceramics and resorbable particle impregnated bone cement to take advantages of both the immediate fixation offered by the bone cement and long term fixation due to tissue ingrowth.

Bone Cements↗
PubMed1999

Audit of ketoprofen prescribing after orthopedic and general surgery.

PURPOSE: In 1994, we developed a practice guideline which stated that ketoprofen should be used in every adult patient after surgical procedures for which at least moderate pain was anticipated. The dose recommended was 50 mg every six hours i.v. in the operating room followed by oral administration as soon as possible for three days. The purpose of this study was to evaluate the success of the guideline implementation. METHODS: In 1995, an audit performed by a research pharmacist assistant under the supervision of the authors analysed prospectively the files of patients scheduled for orthopedic or general surgery during a one-month period. The compliance of the nurses was also recorded. RESULTS: Of 185 patients operated upon during the period, seven were transferred to the ICU and were not evaluated. Ketoprofen was not prescribed to 112 (63%) of the 177 remaining patients, either because minor pain was expected (n = 55) or because one or several contra-indications to its use were detected. In cases where ketoprofen was used although theoretically contraindicated (11%), review of the medical records and interviews of anesthesiologists showed that prescription was guided by a risk/benefit analysis. In 18% of cases, nurses did not administer at least one dose of ketoprofen although medical prescription requested regular administration. CONCLUSION: Although the use of NSAIDs is still controversial, implementation by anesthesiologists of a practice guideline introducing ketoprofen for postoperative analgesia was successful and the nursing non-compliance rate to follow written orders was modest.

Administration, Oral↗
PubMed2002

Titration of isoflurane using BIS index improves early recovery of elderly patients undergoing orthopedic surgeries.

PURPOSE: This study was designed to investigate the effect of bispectral index (BIS) monitoring on the recovery profiles, level of postoperative cognitive dysfunction, and anesthetic drug requirements of elderly patients undergoing elective orthopedic surgery with general anesthesia. METHODS: Sixty-eight patients over the age of 60 were randomized into one of two groups. In the standard practice (SP) group, the anesthesiologists were blinded to the BIS value, and isoflurane was titrated according to standard clinical practice. In the BIS group, isoflurane was titrated to maintain a BIS value between 50-60. RESULTS: The total isoflurane usage was 30% lower in the BIS group compared to the SP group (5.6 +/- 3 vs 7.7 +/- 3 mL, P <0.05). The time to orientation was faster in the BIS group compared to the SP group (9.5 +/- 3 vs 13.1 +/- 4 min, P <0.001). There were no differences in the postoperative psychometric tests between the two groups. CONCLUSIONS: There was no difference in the level of postoperative cognitive dysfunction between the two groups. However, titration of isoflurane using the BIS index decreased utilization of isoflurane and contributed to faster emergence of elderly patients undergoing elective knee or hip replacement surgery.

Aged↗
PubMed2005

Two injections of erythropoietin correct moderate anemia in most patients awaiting orthopedic surgery.

BACKGROUND: The primary objective of this study was to assess the number of erythropoietin (EPO) injections required to reach a hematocrit (Ht) of 40% in moderately anemic patients. The secondary objective was to compare this strategy with autologous blood donation (ABD) in elective orthopedic surgery in terms of red blood cell (RBC) production. STUDY DESIGN AND METHODS: 93 patients with a baseline Ht between 30 and 39% were randomized into two groups the day of the preoperative assessment. In the EPO group, patients received 40,000 UI/week sc until they reached a maximal Ht of 40%. In the ABD group, a RBC pack was collected every week as long as the Ht was above 33%. RESULTS: Two EPO injections were necessary to reach a 40% Ht in 63% of the patients. It was possible to collect two RBC packs in 45% of the patients in the ABD group. Volume of RBC production was significantly higher in the EPO group: 268 +/- 142 mL vs 141 +/- 129 (P = 0.0001). In the EPO group, Ht was significantly higher on days one and three after surgery and at discharge. The energy score was better in the EPO group. In the ABD group, 12.6% patients vs 6.5% in the EPO group received allogeneic transfusion (ns). CONCLUSION: Only two EPO injections were sufficient to reach a Ht of 40% in the majority of patients. Therefore, to improve cost/effectiveness, the number of EPO injections should be related to baseline Ht instead of the four injections recommended in the product monograph.

Aged↗
PubMed1995

Clinical application of computed radiography in orthopedic surgery.

Since 1988, Fuji Computed Radiography (FCR) system (Fuji Medical Systems, Tokyo, Japan) has been used at Osaka Prefectural Hospital (Osaka, Japan) for all kinds of images. In this paper, we discuss the advantages and disadvantages of computed radiography (CR) images from the standpoint of an orthopedic surgeon. Contours, which can not be seen on conventional radiographs, are clearly visualized on the CR image. Adequate information for diagnosis can be obtained with a great reduction in x-ray exposure during the screening of scoliosis or congenital dislocation of hip joint. However, because the scale is reduced by one half in antero-posterior views of the bilateral hip joint, CR images are unsuitable for postoperative measurement of total hip arthroplasty (THA). Furthermore, caution is required because the clear zone after THA is emphasized on edge-enhanced CR image.

Absorptiometry, Photon↗
PubMed2005

Nonsteroidal anti-inflammatory drugs (NSAIDs) in the perioperative phase in traumatology and orthopedics effects on bone healing.

OBJECTIVE: To achieve analgesic, anti-inflammatory and antipyretic effects in traumatology and orthopedic surgery without side effects or with the least possible side effects, with special emphasis on bone healing. INDICATIONS: Acute and chronic inflammatory conditions, e. g., rheumatoid arthritis, ankylosing spondylitis. Degenerative joint disease. Posttraumatic and postoperative pain, edema, or fever. Prevention of heterotopic bone formation. CONTRAINDICATIONS: Hypersensitivity. Gastrointestinal ulceration or bleeding. Severe hepatic or renal impairment. RESULTS: Nonsteroidal anti-inflammatory drugs (NSAIDs) are invaluable in treating a variety of musculoskeletal conditions. As well as their excellent analgesic potency their anti-inflammatory effects are beneficial in treating posttraumatic and postoperative edema. In addition, NSAIDs inhibit heterotopic bone formation after hip arthroplasty. Animal studies, however, have demonstrated that they cause delayed fracture healing. Although clinical studies have not yet supplied unequivocal evidence of this effect in human subjects, the authors recommend that in the presence of other risk factors which may adversely affect fracture healing, such as smoking, diabetes mellitus or peripheral arterial occlusive disease, the indication of NSAID use for analgesia should be strictly limited. Therapeutic alternatives such as centrally acting agents (e. g., weak opioids) should be considered in these patients.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1998

[Dose-response relationship of clonidine with epidural administration of ropivacaine in orthopedic procedures of the lower extremities].

OBJECTIVE: The aim of this study was to investigate preliminarydose-range effects of clonidine added to ropivacaine for epidural analgesia in elective orthopedic surgery of the lower limbs with doses, causing a minimum of cardiovascular side effects. METHODS: 60 patients were randomly assigned to receive in a double-blind fashion a mixture of 1 mg/cm height ropivacaine plus saline or 1 mg/cm ropivacaine plus 25 micrograms, 50 micrograms, 75 micrograms, 100 micrograms or 150 micrograms clonidine for epidural analgesia. The sensory and motor function were determined at defined time intervals for 30 minutes. Heart rate and blood pressure were controlled and sedation score was judged. The postoperative 2-segment-regression of pin-prick and the onset of pain were recorded. RESULTS: The six groups were comparable in demographic data and in term of onset time. The prolongation of analgesia reached 513 +/- 92 min (p = 0.002) for 150 micrograms clonidine, 460 +/- 148 min (p = 0.073) for 100 micrograms clonidine, 440 +/- 86 min (p = 0.057) for 75 micrograms clonidine compared with 347 +/- 114 min for saline. In an equal manner, 2-segment-regression for pin-prick was extended to 251 +/- 47 min (p = 0.018) for 150 micrograms clonidine, 238 +/- 33 min (p = 0.034) for 100 micrograms clonidine, 229 +/- 29 min (p = 0.027) for 75 micrograms clonidine and 178 +/- 43 min for saline. Heart rate dropped down in all groups. Mean arterial pressure decreased significantly in the groups with 75, 100 and 150 micrograms clonidine. Sedation score increased continuously from 0.6 +/- 0.5 (saline) to 1.8 +/- 0.8 (150 micrograms clonidine). CONCLUSION: We conclude that 150 micrograms clonidine significantly enhances the duration of analgesia of epidurally administered ropivacaine in a mean of 171 mg. This time interval is longer than the one with 200 mg ropivacaine alone. But, there are side effects in form of decrease of arterial pressure. Cardiovascular monitoring seems to be essential. Because of the enhanced analgesia duration, the time interval for reloading epidural anaesthesia are increased.

Adrenergic alpha-Agonists↗
PubMed2003

[Clinical trials in orthopedic and trauma surgery: randomized or non-randomized?].

Drawing inferences on a causal relationship between a particular intervention and the observed outcome requires to conduct a clinical experiment which controls for study conditions and systematic errors (bias). This is best to be achieved by randomization in which known and unknown biological risk factors are distributed equally among treatment arms. Trauma and orthopedic surgery,however, occupies an exceptional position in clinical medicine. Random allocation of subjects is often considered difficult because of the tight time frame between patient presentation and the urgent need for surgical treatment, and the dependence of operative results upon technical skills. Evidence of a true treatment effect does not only depend on design issues (i.e., randomized or non-randomized treatment assignment), but on both the prior probability of efficacy and the observed effect size as well. Even though our knowledge of the efficacy of osteosynthesis comparing with, let's say, plaster immobilization or (fictive) placebo therapy is hardly supported by randomized trials, the biologically plausible principle of stable operative fixation of fracture fragments has established itself as the scientific basis to propagate surgical rather than other treatment options. Thus, the efficacy of a medical intervention can be well demonstrated without randomization. Regarding the ultimate goals of stabilization, pain removal, and mobilization,osteosynthesis of a pertrochanteric fracture fits these principles in terms of an all-or-none effect (so called level Ic evidence): without the intervention, effects will not be observed. On the other hand, endpoints such as healing and infection rates or duration of rehabilitation may be severely influenced by confounding factors (e.g., concomitant diseases, age, or gender). Under these circumstances,the goal of quantifying treatment effects of different interventions (i.e., interlocking nails, plates, K-wires) and of discriminating these effects from bias might be solved more reliably by a randomized than by a non-randomized trial.Obviously,the need for randomization relies on the choice of the main endpoint of interest.The postulated overestimation of treatment effects by nonrandomized trials has been proven only for methodologically weak investigations. In contrast, high quality studies led to comparable findings regardless of randomization. In conclusion, there are thinkable alternative designs to randomized trials in trauma surgery, accounting for selected clinical questions and objectives. It must be emphasized that these designs will require a similarly rigorous planning (i.e., study protocols, ethics, sample size considerations) and analysis of the results.

Bias↗
PubMed2003

[Radiation dosage in orthopedics -- a comparison of computer-assisted procedures].

Since the 1990s, computer-assisted methods have been well-established in the field of orthopedics and traumatology. In addition to the proven improvement in the field of surgical precisioncompared with conventional techniques, the decrease in the amount of emitted ionizing radiation inside of the operating room was cited to constitute an additional major advantage of computer-based navigation. The goal of this study was to quantify X-ray dose values exposed during both conventional methods and computer-assisted procedures, the latter being performed using a C-arm device SIREMOBIL Iso-C3D (Siemens Medical Solutions). The clinical measurements were supplemented by laboratory experiments using a pinpoint ionization chamber placed inside a standard lucite phantom. The clinical part of the study investigated the application of new, i.e. computer assisted, techniques in comparison with conventional procedures on in total 42 patients experiencing surgery either on their lower extremities (n = 14) or on the spine (n = 28). The techniques applied were: (1) conventional surgical procedure, (2) CT-based navigation, (3) C-arm navigation, and (4) Iso-C3D-navigation. The main focus of the clinical evaluation was the determination of radiation dose values by means of thermoluminescence dose meters, accompanied by the registration of the operation times of the X-ray tube during a surgical intervention. The conclusions from the clinical studies are in agreement with the results from the laboratory measurements. Computer-assisted techniques led to a significant reduction in X-ray dose exposure and drastically shortened irradiation times. The most pronounced decrease in the emission of ionizing radiation was achieved in case of the Iso-C3D-navigation, which has only recently been introduced into clinical practice, i.e. during runtime of this study.

Humans↗