Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “DISLOCATIONS”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 631 records · Page 35Linked to original sources
PubMed1997

Patellar dislocation in Rubenstein-Taybi syndrome.

This report describes 11 patients with Rubinstein-Taybi syndrome (RTS) and patellar dislocation. The age at diagnosis of patellar dislocation ranged from birth to 16 years. Ten patients had chronic dislocations and 8 of 11 had bilateral patellar dislocations. Eight patients required surgical stabilization of the patella; most achieved a good outcome with surgical repair. All families reported that the patellar dislocations impaired developmental skills which improved after surgery. Seven of the 11 patients were described as having other joint abnormalities including congenital dislocations and laxity of the joints. Patients with RTS should undergo regular thorough joint examinations, including the knees, because abnormalities may result in delay of attainment of motor skills.

Adult↗
PubMed1997

[Biomechanics and semiology of transient lateral patellar dislocation: reliability of magnetic resonance diagnosis].

Transient patellar dislocation is a rare finding. It is usually due to direct trauma in mediolateral direction or to indirect trauma related to violent quadriceps muscle contraction. The clinical diagnosis of transient forms is usually rather difficult because the associated signs (hemarthros and pain at the joint and/or at the vastus medialis insertion) are not specific. Conventional radiography and CT are very accurate in bone studies, but exhibit major limitations in the detection of capsular injuries with intramedullary and/or cartilaginous bone involvement. We investigated MR diagnostic reliability in the study of the injuries caused by transient patellar dislocation. 526 MR examinations of the knee were reviewed retrospectively; fifteen of them were positive for transient patellar dislocation. We used a .5 T superconductive MR unit with a circumferential extremity coil. Axial, coronal and sagittal T1-weighted spin echo, T2*-weighted gradient echo and axial STIR images were acquired. The following criteria were considered specific for the diagnosis of former lateral patellar dislocation: retinacular changes; patella site; signal intensity changes in femoral and patellar intramedullary bone; joint effusion; cartilage and subchondral bone changes. All the patients with transient patellar dislocation had hemarthros with inner retinaculum involvement. The femoropatellar joint was incongruous in 115 cases; patellar subluxation was external in 8/11 patients and lateral in the remaining 3 patients. Medullary bruises were found in 8/15 cases and cartilage injuries in 13/15. Finally, other joint components, such as the posterior horn of the medial meniscus or the anterior cruciate ligament were involved in 6/13 cases. Arthroscopy was performed in 6 patients with associated injuries and confirmed all MR findings (100% agreement). To conclude, in our experience MRI was a very reliable tool to study the injuries due to transient patellar dislocation because it showed specific changes and possible associated traumas, which helps choose the most suitable treatment.

Adolescent↗
PubMed1993

Simulation of dislocations imaged by moiré fringe contrast.

Transmission electron microscope (TEM) images of dislocations as produced via moiré fringe contrast are simulated using many-beam diffraction theory. The effect of edge dislocations on both parallel and rotational moiré fringe patterns is considered. For the parallel moiré fringe pattern, images of dislocations both perpendicular to the film plane and those inclined to the film plane are produced. The effect of an inclined dislocation is shown to cause a distortion of the dislocation image. Finally, a comparison between predicted and experimentally observed images is made, with the results indicating that threading dislocations in the FeAl/GaAs system have line directions nearly perpendicular to the (001)FeAl/GaAs film plane.

Mathematics↗
PubMed2006

HRTEM of dislocation cores and thin-foil effects in metals and intermetallic compounds.

Examples of the observation and analysis of dislocation cores and dislocation fine structure in metals and intermetallics using high resolution transmission electron microscopy are discussed. Specific examples include the 60 degrees dislocations in aluminum, a011 edge dislocations in NiAl, and screw dislocations in Ni3Al. The effect of the thin TEM foils on the structure and imaging of these dislocations is discussed in light of embedded atom method calculations for several configurations and coupled with image simulations. Some generalizations based on these calculations are discussed. These analyses enables determination of the spreading or decomposition of the edge component of the cores, both in and out of the glide plane, which can have significant implications for the modeling of macroscopic behavior.

Aluminum↗
PubMed2005

Late dislocation of scleral-sutured posterior chamber intraocular lenses.

PURPOSE: To examine a recent series of late scleral-sutured posterior chamber intraocular lens (PCIOL) dislocations to identify possible causes and preventive measures. SETTING: Price Vision Group, Indianapolis, Indiana, USA. METHODS: In this retrospective non-comparative interventional case series, 5 consecutive patients received treatment for dislocated scleral-sutured PCIOLs between July 2002 and March 2004. Dislocated lenses were resutured or replaced with another scleral-sutured PCIOL. RESULTS: Dislocation of scleral-sutured PCIOLs occurred 7 to 14 years after implantation. Four dislocations were spontaneous, and 1 was precipitated by trauma. In each case, the suture affixing 1 or both haptics failed. There was no evidence that the suture had eroded through the tissue or that the knot had untied. Microscopic analysis of an explanted IOL with remnants of the suture attached showed localized degradation and cracking of the polypropylene suture material where it had been embedded in the scleral tissue. CONCLUSION: Suture-fixated PCIOLs can dislocate due to degradation of the suture material over time. The use of larger diameter (9-0 instead of 10-0) polypropylene suture material and placement of the haptic and sutures in the ciliary sulcus to promote attachment of scar tissue may enhance the long-term stability of scleral-fixated PCIOLs.

Adult↗
PubMed1997

Surgical management of posteriorly dislocated silicone plate haptic intraocular lenses.

PURPOSE: To report a large series of delayed posterior dislocation of silicone plate haptic intraocular lenses after Nd:YAG laser capsulotomy and discuss the surgical management of this complication. METHODS: We reviewed the records of 11 consecutive patients (11 eyes) with delayed onset of posterior dislocation of a plate haptic silicone intraocular lens. The cause of the posterior capsular defect, time to dislocation, surgical management techniques, complications, and visual outcome were recorded. RESULTS: In eight of the 11 eyes, the silicone plate haptic intraocular lens dislocated an average of 1.8 months (range, 0 to 6.5 months) after Nd:YAG posterior capsulotomy. The other three eyes had surgical complications at the time of cataract extraction that compromised posterior capsular or zonular integrity and led to silicone plate haptic intraocular lens dislocation from 9 weeks to 6 months (mean, 3.6 months) postoperatively. Surgical management consisted of pars plana vitrectomy with intraocular lens repositioning (six eyes) or exchange (five eyes). The average follow-up period after intraocular lens repositioning or exchange was 6.5 months (range, 1 to 14 months). Best-corrected visual acuity at the last follow-up examination measured 20/40 or better in all but one eye that had preexisting macular disease. CONCLUSIONS: Cataract surgeons and patients should be aware of the potential for plate haptic silicone intraocular lenses to undergo delayed posterior dislocation through capsular defects. This complication can be managed effectively with vitrectomy and either repositioning or exchange of the implant. Postoperative visual acuity is generally excellent, and complications are minimal.

Adult↗
PubMed2002

Scleral fixation suture technique without lens removal for posteriorly dislocated intraocular lenses.

BACKGROUND: Posterior chamber intraocular lenses (IOLs) may dislocate into the vitreous or over the retina at the time of, or several months after, surgery or following injury. Techniques described to reposition dislocated lenses have drawbacks, such as lens removal, lens exchange, difficulties of lens repositioning procedures and high cost We describe a technique in which the haptics of dislocated IOLs are fixed to the sclera after the haptics are externalized solely through a pars plicata incision site and tied with a 10-0 Prolene suture. METHODS: After pars plana vitrectomy, the IOL was grasped with an intraocular forceps and moved to the pupillary area. A second intraocular forceps was inserted from the site of planned fixation, and the tip of the haptic was pulled out and heated to form a knob to avoid suture slipping. A 10-0 Prolene suture was then tied to the haptic by means of a sailor knot The haptic was reinserted intraocularly, and the outstaying sutures were tied with conventional knots over the sclera or under the scleral flaps. The procedure was then repeated on the other side. RESULTS: This technique has been used in 12 patients (12 eyes), 7 men and 5 women ranging in age from 45 to 77 (mean 63.8 [standard deviation 8.5]) years. The time between diagnosis of dislocation and surgery was 10 to 20 days in six cases and 21 to 39 days in six cases. The IOL was dislocated into the vitreous in eight cases (67%) and over the retina in four cases (33%). The preoperative best corrected visual acuity ranged from 20/200 to 20/30. Intraoperatively, mild vitreous hemorrhage developed in two patients (17%), macular edema developed in two patients (17%), and rhegmatogenous retinal detachment developed in one patient (8%). The final visual acuity ranged from 20/50 to 20/20 in 11 patients; the patient with retinal detachment had hand movement vision. INTERPRETATION: The technique of scleral fixation of posteriorly dislocated IOLS without lens removal is a safe, inexpensive and useful complement to other techniques.

Aged↗
PubMedDate not supplied

Histologic examination of dislocated lenses.

PURPOSE: To examine histological changes resulting from dislocated and subluxated lenses. CASES: The subjects consisted of 16 patients (aged 52-89 years) who underwent total lens extraction for lens dislocation or subluxation in the Department of Ophthalmology at Fukui Medical University during the period between April 1991 and June 1998. There were 5 patients (6 eyes) with traumatic dislocation and 11 patients (11 eyes) with idiopathic dislocation. RESULT: Rupture of the cortical fibers and migration of the epithelial cells toward the posterior pole of the lens were more frequently noted in patients with traumatic dislocation than in the idiopathic group, and both findings were often simultaneously observed. Rupture of the cortical fibers was considered attributable to external pressure transmitted to the lens. CONCLUSION: We speculate that the concurrent migration and dislocation of the equatorial bow architecture toward the posterior pole was caused by inhibition of differentiation of the epithelial cells to fiber cells by external pressure on the equatorial region.

Aged↗
PubMed2001

Spontaneous late dislocation of intraocular lens within the capsular bag in pseudoexfoliation patients.

PURPOSE: To identify a delayed complication of cataract surgery in patients with zonular weakness caused by pseudoexfoliation syndrome. DESIGN: Retrospective observational case series. PARTICIPANTS: Eight eyes in seven patients with clinically diagnosed pseudoexfoliation syndrome who had undergone previous uncomplicated cataract extraction and placement of a posterior chamber intraocular lens. METHODS: This study evaluated eight cases of late spontaneous dislocation of posterior chamber intraocular lenses within the capsular bag in patients with pseudoexfoliation syndrome. Data were gathered retrospectively from patients' operative reports, medical records, and pathology reports. MAIN OUTCOME MEASURES: (1) Interval between original surgery and dislocation; (2) final best-corrected visual acuity and ocular outcome. RESULTS: All patients had a diagnosis of pseudoexfoliation syndrome and had previously undergone uncomplicated cataract surgery. No patient had any other predisposing factors that would lead to zonular dehiscence or weakness. Delayed dislocation of the entire capsular bag containing the intraocular lens (IOL) occurred spontaneously in all cases. Mean time from IOL implantation to dislocation was approximately 85 months (7 years and 1 month; range, 57-115 months) after surgery. Seven eyes were treated successfully with IOL exchange: six with placement of an anterior chamber IOL and one with scleral fixation of a posterior chamber IOL. The remaining case was treated by scleral fixation of the dislocated IOL. Gross pathology analysis of seven cases confirmed the presence of the IOL within the intact capsular bag. Six eyes have achieved final best-corrected visual acuity of 20/40 or better. CONCLUSION: Patients with pseudoexfoliation syndrome may be at risk for delayed spontaneous dislocation of IOL within the capsular bag after uncomplicated cataract surgery. Awareness of this newly recognized long-term complication may justify a reevaluation of surgical considerations for cataract removal in these patients.

Aged↗
PubMed1998

Removal of dislocated intraocular lenses using pars plana vitrectomy with placement of an open-loop, flexible anterior chamber lens.

OBJECTIVE: There are many alternatives available to the vitreoretinal surgeon in the management of posteriorly dislocated intraocular lenses (IOL). The lens may be repositioned in the ciliary sulcus if there is adequate capsular support, but if this support is absent, it must either be sutured in place (to the sclera or iris) or exchanged for an anterior chamber (AC) IOL. Scleral-sutured IOLs can be associated with hemorrhage, cystoid macular edema, retinal detachment, and endophthalmitis (through the suture tract), and use sutures that must last for the lifetime of the patient. Anterior chamber IOLs (ACIOLs) are easier to implant but require a limbal incision for insertion. The authors sought to determine the safety and efficacy of combining removal of posteriorly dislocated IOLs with ACIOL placement. DESIGN: A retrospective chart review, in which all cases of dislocated IOLs managed at the authors' institution over the last 5 years were reviewed. Patient characteristics, pre-existing ocular conditions, preoperative visual acuity (VA), intraocular pressure (IOP), type of lens dislocated, operation performed, postoperative VA and IOP, and length of follow-up were recorded. RESULTS: A total of nine cases were identified. Seven of these underwent primary posterior chamber (PC) IOL removal with ACIOL implantation. One had an ACIOL placed after a sulcus-sutured PCIOL dislocated, and one had enough capsular support for placement of a PCIOL after removal of a plate haptic silicone lens. Of the seven primary ACIOL cases, the best-corrected VA improved in five cases, was unchanged in one (remained 20/20), and declined in another. The final postoperative VA (mean follow-up, 12 months) was 20/30 or better in five patients, and was limited by age-related macular degeneration and epiretinal membrane in the other two. A hyphema occurred in two patients and cleared in both without visual compromise. There was no evidence of corneal compromise or exacerbation of glaucoma in any of the patients. CONCLUSIONS: Given that the results and complication rates in this small series appear to be similar to those reported for sulcus-suture techniques, implantation of an ACIOL after removal of a posteriorly dislocated IOL appears to be a viable alternative to suture fixation in the absence of capsular support.

Adult↗
PubMed2003

Dislocation after polyethylene liner exchange in total hip arthroplasty.

Little has been published on the outcomes of polyethylene liner exchanges for wear or osteolysis. We assessed 24 patients from our clinic who had an isolated polyethylene liner exchange for wear or osteolysis with retention of the acetabular shell and femoral stem. At a mean 56-month follow-up time, 6 hips (25%) had dislocated. Of these, 2 underwent repeat surgery for recurrent dislocation; 1 had 3 dislocations; 1 had 2 dislocations; and 2 had single dislocations. Seventeen of the remaining patients answered our questionnaire: 13 recovered faster from the polyethylene liner exchange than from the primary arthroplasty; 4 believed that their hips were not as stable, 4 believed the hip did not function as well; and 1 underwent revision for cup loosening. We conclude that polyethylene liner exchanges, with or without femoral head exchange for wear or osteolysis, are associated with a high risk of dislocation and possible decrease in function.

Arthroplasty, Replacement, Hip↗
PubMed2004

Screw dislocations in GaN grown by different methods.

A study of screw dislocations in hydride-vapor-phase-epitaxy (HVPE) template and molecular-beam-epitaxy (MBE) overlayers was performed using transmission electron microscopy (TEM) in plan view and in cross section. It was observed that screw dislocations in the HVPE layers were decorated by small voids arranged along the screw axis. However, no voids were observed along screw dislocations in MBE overlayers. This was true both for MBE samples grown under Ga-lean and Ga-rich conditions. Dislocation core structures have been studied in these samples in the plan-view configuration. These experiments were supported by image simulation using the most recent models. A direct reconstruction of the phase and amplitude of the scattered electron wave from a focal series of high-resolution images was applied. It was shown that the core structures of screw dislocations in the studied materials were filled. The filed dislocation cores in an MBE samples were stoichiometric. However, in HVPE materials, single atomic columns show substantial differences in intensities and might indicate the possibility of higher Ga concentration in the core than in the matrix. A much lower intensity of the atomic column at the tip of the void was observed. This might suggest presence of lighter elements, such as oxygen, responsible for their formation.

Gallium↗
PubMed2006

Signal peptide peptidase is required for dislocation from the endoplasmic reticulum.

Human cytomegalovirus (HCMV) prevents the display of class I major histocompatibility complex (MHC) peptide complexes at the surface of infected cells as a means of escaping immune detection. Two HCMV-encoded immunoevasins, US2 and US11, induce the dislocation of class I MHC heavy chains from the endoplasmic reticulum membrane and target them for proteasomal degradation in the cytosol. Although the outcome of the dislocation reactions catalysed is similar, US2 and US11 operate differently: Derlin-1 is a key component of the US11 but not the US2 pathway. So far, proteins essential for US2-dependent dislocation have not been identified. Here we compare interacting partners of wild-type US2 with those of a dislocation-incompetent US2 mutant, and identify signal peptide peptidase (SPP) as a partner for the active form of US2. We show that a decrease in SPP levels by RNA-mediated interference inhibits heavy-chain dislocation by US2 but not by US11. Our data implicate SPP in the US2 pathway and indicate the possibility of a previously unknown function for this intramembrane-cleaving aspartic protease in dislocation from the endoplasmic reticulum.

Amino Acid Sequence↗
PubMed2004

Dynamic transitions from smooth to rough to twinning in dislocation motion.

The motion of dislocations in response to stress dictates the mechanical behaviour of materials. However, it is not yet possible to directly observe dislocation motion experimentally at the atomic level. Here, we present the first observations of the long-hypothesized kink-pair mechanism in action using atomistic simulations of dislocation motion in iron. In a striking deviation from the classical picture, dislocation motion at high strain rates becomes rough, resulting in spontaneous self-pinning and production of large quantities of debris. Then, at still higher strain rates, the dislocation stops abruptly and emits a twin plate that immediately takes over as the dominant mode of plastic deformation. These observations challenge the applicability of the Peierls threshold concept to the three-dimensional motion of screw dislocations at high strain rates, and suggest a new interpretation of plastic strength and microstructure of shocked metals.

Iron↗
PubMed2006

X-ray microbeam measurements of individual dislocation cell elastic strains in deformed single-crystal copper.

The distribution of elastic strains (and thus stresses) at the submicrometre length scale within deformed metal single crystals has remarkably broad implications for our understanding of important physical phenomena. These include the evolution of the complex dislocation structures that govern mechanical behaviour within individual grains, the transport of dislocations through such structures, changes in mechanical properties that occur during reverse loading (for example, sheet-metal forming and fatigue), and the analyses of diffraction line profiles for microstructural studies of these phenomena. We present the first direct, spatially resolved measurements of the elastic strains within individual dislocation cells in copper single crystals deformed in tension and compression along <001> axes. Broad distributions of elastic strains are found, with important implications for theories of dislocation structure evolution, dislocation transport, and the extraction of dislocation parameters from X-ray line profiles.

Journal Article↗
PubMedDate not supplied

[Risk factors for dislocation of a cementless total hip endoprosthesis--a statistical analysis].

AIM: This retrospective study aimed at the statistical identification of risk factors for dislocation for a certain cementless hip endoprothesis. MATERIAL AND METHOD: At our department 2605 primary total hip arthroplasties were performed between 1987 and 1997. In 40 patients (1.5%) a dislocation occurred. These patients were compared with a control group matched in number. RESULTS: No difference was found in both groups with respect to age, height, weight, body-mass index, and diagnosis. A tendency was found that more males were involved in the dislocation group. There were more previous operations found in this group (p = 0.005). Also significant was the fact, that patients in the dislocation group more often had epidural anaesthesia (p = 0.02), more often the implantation of the smaller 28-mm head (vs. 32 mm) (p = 0.02), and a higher inclination angle of the acetabular component (p = 0.02). No difference was found in terms of the surgeons experience, the postoperative leg length, femoral offset, medialisation, cranialisation and antetorsion of the acetabular component. CONCLUSION: Dislocation after total hip arthroplasty is a multifactorial complication. With the use of the Alloclassic/Zweymüller total hip endoprothesis, a higher risk for dislocation was found for patients with previous hip surgery, the use of the smaller endoprosthesis head, a high acetabular inclination angle, and in the use of epidural anaesthesia.

Aged↗
PubMedDate not supplied

[Polyethylene liner dislocation in Harris Galante acetabular components].

AIM: Dislocation and subsequent dissociation of the polyethylene liner as a result of failure of the acetabular locking mechanism is a potential source of failure in the Harris-Galante acetabular component. The purposes of this study are to present seven cases with a liner dislocation due to failure of the liner locking mechanism. METHOD: Between March 1997 and December 2001, seven patients who had had a total hip arthroplasty presented with clinical and radiologic signs of liner dislocation and signs of polyethylene wear of the liner from a Harris Galante acetabular shell. In all cases the intraoperative findings showed evidence of failure of the liner locking mechanism and subsequent dislocation. The medical records, radiographs, operative notes and explanted retrieved components were reviewed. RESULTS: The components had been in situ for an average of 5.3 years (range 1-9 years). Two components were first generation, five were second generation. The symptoms developed spontaneously in five patients, the other two patients described a minor trauma. Radiographs showed eccentric position of the head in all cases. All acetabular components showed an excellent stability intraoperatively, nevertheless we had to remove the well fixed acetabular shell due to complete destruction of the liner locking mechanism in two cases. Treatment consisted of revision of the shell in two patients and exchange of the liner in five patients. All retrieved liners showed severe deformation and/or fracture of the rim. CONCLUSION: Harris Galante modular acetabular components have been used widely for primary and revision arthroplasty. The survival of this implant has been well documented in the literature. Failure of the liner locking mechanism and following dislocation or fracture of the polyethylene liner is a potential cause of failure which may possibly occur more often than the literature to date has documented. We report seven cases of liner dislocation, in which two acetabular components had to be removed completely due to destruction of the liner locking mechanism. In the other five cases exchange of the liner was possible thanks to well timed revision. We believe that, as the liner wears and becomes loose due to an inefficient locking mechanism, the load increases on the polyethylene rim until it deforms or fractures. As a consequence of the prosthetic design at that stage nothing can prevent the liner from rotating out of the shell.

Acetabulum↗
PubMed2006

SEL1L, the homologue of yeast Hrd3p, is involved in protein dislocation from the mammalian ER.

Protein quality control in the endoplasmic reticulum (ER) involves recognition of misfolded proteins and dislocation from the ER lumen into the cytosol, followed by proteasomal degradation. Viruses have co-opted this pathway to destroy proteins that are crucial for host defense. Examination of dislocation of class I major histocompatibility complex (MHC) heavy chains (HCs) catalyzed by the human cytomegalovirus (HCMV) immunoevasin US11 uncovered a conserved complex of the mammalian dislocation machinery. We analyze the contributions of a novel complex member, SEL1L, mammalian homologue of yHrd3p, to the dislocation process. Perturbation of SEL1L function discriminates between the dislocation pathways used by US11 and US2, which is a second HCMV protein that catalyzes dislocation of class I MHC HCs. Furthermore, reduction of the level of SEL1L by small hairpin RNA (shRNA) inhibits the degradation of a misfolded ribophorin fragment (RI332) independently of the presence of viral accessories. These results allow us to place SEL1L in the broader context of glycoprotein degradation, and imply the existence of multiple independent modes of extraction of misfolded substrates from the mammalian ER.

Animals↗