Metal Cup Research Articles

Cementless total hip arthroplasty using porous-coated Biomet acetabular cups (Hexloc and Ringloc types)

This study examined the mid-term (more than 5 years) results of cementless total hip arthroplasty (THA) using Biomet acetabular cups (locking mechanism: Hexloc type or Ringloc type). A series of 58 patients (70 hips) who had undergone cementless THA at our department were available for inclusion in this study. The average age at surgery was 55.2 years, and the average follow-up was 6 years 10 months. Osteolysis occurred in five cases. In the group with osteolysis, the average annual linear wear was 0.18 mm/year, and in the group without osteolysis it was 0.10mm/year. The higher linear wear rate in the osteolysis group was statistically significant compared to that in the nonosteolysis group. The age of the patient was closely related to polyethylene (PE) wear in the Hexloc group but not in the Ringloc group. In the Ringloc group there was no close correlation between the thickness of the PE liner and the average annual linear wear, whereas in the Hexloc group the thicker liner had significantly less annual linear wear. It was thought that PE wear of the Hexloc cup was more susceptible to the age of the patient at surgery and the PE thickness than that of the Ringloc cup owing to several structural differences, such as rotational stability and conformity between the metal cup and the PE liner.

The Effect of SR-Modification Treatment on Porosity Formation of Reduced Pressure 319 Al Alloy Castings

The effect of Sr-modification on pore formation in reduced pressure and atmospheric conditions was studied. It was found that in thin wall steel cup conventional specimens, the Sr-modification had no significant effect on pore formation. A new type of metallic cup with a riser was designed for use in a reduced pressure test as a mould. It was designed to improve directional solidification so that no macro shrinkage occurred in test samples. Using this mould, the effect of Sr-modification on pore formation was investigated. The effect of Sr-modification on the increased pore number density and pore volume fraction became significant in both reduced pressure and atmospheric conditions. Also, the results indicate that the effect of Sr-modification on pore formation of reduced pressure samples is not considerable in the melt with a hydrogen content lower than 0.1cc/100g Al.

Magnetic resonance imaging of subdural haemorrhage following instrumental vaginal delivery in clinically normal neonates

This study aimed (1) to image clinically normal newborn infants to detect the presence of any intracranial bleed and (2) to establish the natural history of the bleed. Newborn babies were imaged within 48 hours of delivery and all details of the labour and delivery were recorded. MR imaging was carried out on a dedicated 0.2T Niche MR system on the special care baby unit. Images were obtained in axial and coronal planes using T1, T2 plus gradient echo weighted images; similarly for the follow-up imaging. χ2 test was used for analysis. One hundred and two newborn infants were scanned. Forty-five had a normal vaginal delivery, 10 were ventouse (three metal cup, seven silastic), 10 were emergency sections, 15 were elective sections, 22 were forceps (19 Neville Barnes, three Keillands). Five had subdural collections that were clinically silent throughout their duration and had resolved fully within 4 weeks.All five babies with subdural collections had been delivered by forceps following an attempt at a ventouse delivery. In total 15 babies were delivered by forceps following a ventouse delivery and one by emergency caesarian section following an attempted ventouse delivery. The method of delivery was the only statistically significant factor in these babies (duration of labour, fetal blood pH, etc. were not statistically significant) for the presence of a subdural collection, using the χ2 test (P < 0.001).

Structure of Functional Single AQP0 Channels in Phospholipid Membranes

Aquaporin-0 (AQP0) is the most prevalent intrinsic protein in the plasma membrane of lens fiber cells where it functions as a water selective channel and also participates in fiber–fiber adhesion. We report the 3D envelope of purified AQP0 reconstituted with random orientation in phospholipid bilayers as single particles. The envelope was obtained by combining freeze-fracture, shadowing and random conical tilt electron microscopy followed by single particle image processing. Two-dimensional analysis of 2547 untilted images produced eight class averages exhibiting “square” and “octagonal” shapes with a continuum of variation. We reconstructed in 3D five class averages that best described the data set. The reconstructions (“molds”) appeared as metal cups exhibiting external and internal surfaces. We used the internal surface of the mold to calculate the “imprints” that represent the AQP0 particles protruding from the hydrophobic core of the phospholipid bilayer. The complete envelope of the channel, formed by joining the square and octagonal imprints, described accurately the size, shape, oligomeric state, orientation, and molecular weight of the AQP0 channel inserted in the phospholipid bilayer. Rigid body docking of the atomic model of the aquaporin-1 (AQP1) tetramer showed that the freeze-fracture envelope accounted for the conserved transmembrane domain (∼73% similarity between AQP0 and AQP1) but not for the amino and carboxyl termini. We suggest that the discrepancy might reflect differences in the location of the amino and carboxyl termini in the crystal and in the phospholipid bilayer.

Clinical evaluation of a “hand pump” vacuum delivery device

Objective To evaluate the clinical performance of a hand-held vacuum delivery system. Methods Between December 1999 and September 2000, a prospective audit was undertaken of all vacuum deliveries performed at Derby City General Hospital. Results In this period, 3296 deliveries occurred, of which 317 (9.6%) were by vacuum. Of these, data were collected on 300 (94.6%), 78 deliveries with the hand-held vacuum and 222 with standard vacuum. There were no differences in the demographic profiles, indication, gestational age at delivery, or birth weights between the two groups ( P > .05 in all instances). In all types of delivery, nonrotational and rotational, the hand-held vacuum performed comparably to its contemporaries with no increase in delivery “failures” being noted. There were no differences in the extent or frequency of maternal injuries between the instruments, and other than transient scalp abrasions, there were no significant fetal injuries. Conclusion The hand-held vacuum delivery system is a functionally effective addition to the practitioners’ “armory,” providing an alternative to the standard metal and silastic cups.

In-vivo measurement of swine myocardial resistivity

We used a four-terminal plunge probe to measure myocardial resistivity in two directions at three sites from the epicardial surface of eight open-chest pigs in-vivo at eight frequencies ranging from 1 Hz to 1 MHz. We calibrated the plunge probe to minimize the error due to stray capacitance between the measured subject and ground. We calibrated the probe in saline solutions contained in a metal cup situated near the heart that had an electrical connection to the pig's heart. The mean of the measured myocardial resistivity was 319 ohm x cm at 1 Hz down to 166 ohm x cm at 1 MHz. Statistical analysis showed the measured myocardial resistivity of two out of eight pigs was significantly different from that of other pigs. The myocardial resistivity measured with the resistivity probe oriented along and across the epicardial fiber direction was significantly different at only one out of the eight frequencies. There was no significant difference in the myocardial resistivity measured at different sites.

Failed Vacuum Extraction: Maternal Risk Factors and Pregnancy Outcome

Vacuum extraction, more widely used than forceps for operative vaginal delivery in Europe, is said to have failed when it is unduly difficult or there are more than two cup disengagements. This retrospective study of singleton, vertex deliveries at more than 36 weeks' gestation sought to identify obstetrical risk factors for a failed trial of vacuum extraction. A total of 211 trials taking place in the years 1990-1998 were reviewed; 5.4% of attempts (113) failed, leading to cesarean delivery within 15 minutes. Extraction was done only when the cervix was completely dilated, the membranes had ruptured, and the fetal head was engaged. Traction was done slowly and was stopped if there was any loss of vacuum. Pressure was limited to 0.8 kg/cm 2 . Only two reapplications of the metal cup were permitted. Three instances of lost suction were construed as method failure. Failed vacuum extraction was significantly and linearly associated with high birth weights; these infants were likelier to be large for gestational age and to weigh more than 4000 g. A lack of prenatal care also correlated with a higher rate of failed extraction. On multiple logistic regression analysis, both deficient prenatal care and a birth weight greater than 4000 g were independent risk factors for failed vacuum extraction. Women in whom extraction failed had significantly more cervical and uterine tears than when the procedure succeeded, and the relationship with uterine rupture persisted after adjusting for previous cesarean delivery, Failed extraction correlated with postpartum anemia and also with higher rates of intrapartum and postpartum fetal death (odds ratios: 35.9 for intrapartum fetal death and 9.1 for postpartum death). Both maternal and neonatal outcomes are compromised by a failed trial of vacuum extraction. An estimated fetal weight exceeding 4000 g should be viewed as a relative contraindication, particularly for women who have not received adequate prenatal care.

Effect of lap-sheets on deep drawing of metallic foil cups

In order to improve the deep drawability of stainless-steel foil cups, foil-lap blanks in which thin sheet metals ( lap-sheets) were lapped over the foils were used in the deep-drawing operations. In the deep-drawing process, aluminum sheets were used as lap-sheets. The following three foil-lap blanks were used. B-sheet type: a two-ply foil-lap blank in which an aluminum sheet is on the blank holder side. D-sheet type: a two-ply foil-lap blank in which an aluminum sheet is on the die side. Sandwich type: a three-ply foil-lap blank in which a stainless-steel foil blank is sandwiched between two aluminum lap-sheets. In the D-sheet type, cracks on the foil cups were prevented by the lap-sheet on the die side. In the B-sheet type, wrinkles on the foil cups were prevented by the lap-sheet on the blank holder side. The deep drawability of stainless-steel foil cups was improved effectively when using lap-sheets. The thickness and the strain-hardening characteristics of aluminum lap-sheets influenced the deep drawability of foil cups.

The Harris-Galante total hip arthroplasty: A minimum 8-year follow-up study

Abstract: A total of 93 Harris-Galante Porous I (HGP- I) prostheses were analyzed with a mean follow-up of 10.2 years. Thigh pain (28 hips) correlated with unstable fixation (P<.005), female gender (P<.045), young age (P<.05), poor distal femoral fill (P<.002), subsidence (P<.0001), and osteolysis (P<.05). Thirteen stems and 6 metallic shell cups were revised. Kaplan-Meier analysis showed 13-year survival rates of 92.5% ± 5.8% for the metallic shell cup, 79.7% ± 13% for the HGP-I cup, and 76.3% ± 14.0% for the stem. Five polyethylene liners were changed because of wear >1 mm. Radiographic loosening occurred in 8 cups. Radiographic bone ingrowth was present in 54 stems, stable fibrous fixation was present in 24 stems, and unstable fixation was present in 15 stems. The mean polyethylene wear was 0.17 mm/y. Eleven hips (11.8%) had acetabular osteolysis, and 24 (25.8%) had femoral osteolysis, the latter being more frequent in unstable stems (P<.007). The HGP-I metallic cup shows better clinical and radiographic results than the stem, which frequently is associated with pain, unstable fixation, and osteolysis. Excessive polyethylene wear is frequent.

The Elastic Prosthetic Acetabulum. A New Concept and Design of An Acetabular Replacement

PurposeDescription of a new design of acetabular replacement which combines the advantages of a real elasticity of the external metallic cup, following the natural movements of the acetabulum with those of a hard rubbing couple.MaterialsA trifoliate metal back cup is described: one part, zenithal, is firm while the two others, laterals and lowers, work to adapt to movements and to gradual future changes of the acetabulum. Its special design allows the polyethylene (PE) insert to remain independent of the working parts.Patients and ResultsA clinical experimentation of only 33 cases, by precaution, has been carried out, under rules of the French Huriet's law, and is reported after a follow up of three years. This cup has already produced promising results with the average of Mèrle d'Aubigné and Postel score at 17.31/18 and a Harris hip score at 88.4 points.ConclusionThese results are an encouragement to go ahead with its development.

Komplette Luxation des PE-Inlays nach innerer Hemipelvektomie und individueller Tumorendoprothese

We report about an exceptional complication after internal hemipelvectomy and replacement of the defect with a custom-made endoprosthesis. A complete luxation of the PE-inlay out of the metal cup occurred. Radiologically we assumed a luxation of the femoral head in dorsal direction. Revision after a failed attempt of closed reposition showed a complete luxation of the inlay, which was caused by deficient fixation in the acetabular component. The absence of a contrast wire in the PE-inlay delayed the right diagnosis and made it difficult to find the dislocated inlay in the large wound.

Practice Makes Within 5% of Perfect: Visual Perception, Motor Skills, and Memory in Artifact Variation

Practice Makes Within 5% of Perfect: Visual Perception, Motor Skills, and Memory in Artifact Variation

Soft versus rigid vacuum extractor cups for assisted vaginal delivery.

The original cups used for vacuum extraction delivery of the fetus were rigid metal cups. Subsequently, soft cups of flexible materials such as silicone rubber or plastic were introduced. Soft cups are thought to have a poorer success rate than metal cups. However they are also thought to be less likely to be associated with scalp trauma and less likely to injure the mother. The objective of this review was to assess the effects of soft versus rigid vacuum extractor cups on perineal injury, fetal scalp injury and success rate. We searched the Cochrane Pregnancy and Childbirth Group trials register and the Cochrane Controlled Trials Register. Date of last search: February 2000. Acceptably controlled comparisons of soft versus rigid vacuum extractor cups. Two reviewers assessed trial quality and extracted data. Study authors were contacted for additional information. Nine trials involving 1375 women were included. The trials were of average quality. Soft cups are significantly more likely to fail to achieve vaginal delivery (odds ratio 1.65, 95% confidence interval 1.19 to 2.29). However, they were associated with less scalp injury (odds ratio 0.45, 95% confidence interval 0.15 to 0.60). There was no difference between the two groups in terms of maternal injury. Metal cups appear to be more suitable for 'occipito-posterior', transverse and difficult 'occipito-anterior' position deliveries. The soft cups seem to be appropriate for straightforward deliveries.

Soft Versus Rigid Vacuum Extractor Cups for Assisted Vaginal Delivery

A substantive amendment to this systematic review was last made on 22 June 1999. Cochrane reviews are regularly checked and updated if necessary.ABSTRACT Background and objectives: The original cups used for vacuum extraction delivery of the fetus were rigid metal cups. Subsequently, soft cups of flexible materials such as silicone rubber or plastic were introduced. Soft cups are thought to have a poorer success rate than metal cups. However, they may be less likely to be associated with scalp trauma, easier to apply and less likely to injure the mother. The objective of this review was to assess the effects of soft versus rigid vacuum extractor cups on perineal injury, fetal scalp injury, short and long term pain and success rate. Search strategy: We searched the Cochrane Pregnancy and Childbirth Group trials register. Selection criteria: Acceptably controlled comparisons of soft versus rigid vacuum extractor cups. Data collection and analysis: Two reviewers assessed trial quality and extracted data. Study authors were contacted for additional information. Main results: Nine trials involving 1375 women were included. The trials were of average quality. Soft cups are significantly more likely to fail to achieve vaginal delivery (odds ratio 1.65, 95% confidence interval 1.19–2.29). However, they were associated with less scalp injury (odds ratio 0.45, 95% confidence interval 0.15–0.60). There was no difference between the two groups in terms of maternal injury. Reviewers' conclusions: Metal cups appear to be more suitable for “occipito‐posterior,” transverse and difficult “occipito‐anterior” position deliveries. The soft cups seem to be appropriate for straightforward deliveries. Citation: Johanson RB, Menon BKV. Soft versus rigid vacuum extractor cups for assisted vaginal delivery (Cochrane Review). In: The Cochrane Library, Issue 4, 1999. Oxford: Update Software.••• The preceding reports are abstracts of regularly updated, systematic reviews prepared and maintained by the Cochrane Collaboration. The full texts of the reviews are available in The Cochrane Library (ISSN 1464–780X). See http://www.update‐software.com/cochrane.htm, or contact Update Software,info@update.co.uk, for information on subscribing to The Cochrane Library in your area.Update Software Ltd., Summertown Pavilion, Middle Way, Oxford OX2 7LG, United Kingdom (Tel.: + 44 1865 513902; Fax: + 44 1865 516918).

Influence of a foreign body on the wear of metallic femoral heads and polyethylene acetabular cups of total hip prostheses

Excessive wear of polyethylene in total replacement hip prostheses elicits deleterious biologic reactions and may be thus a limiting factor that compromises the long-term performance of these devices. This study is based on the report of two clinical failures of total hip prostheses with metallic femoral heads and polyethylene acetabular cups. The investigations reveal that foreign bodies (titanium fibermesh pieces) can migrate into the joint space of total hip prostheses and participate in abrasive third-body wear of the polyethylene cups. This excessive wear of polyethylene enhanced by the modification of the metallic counterface roughness is likely to induce the early loosening of the devices.

Direct experimental evidence of lubrication in a metal-on-metal total hip replacement tested in a joint simulator

The purpose of the study reported in this paper was to investigate experimentally the conditions of lubrication and contact between a metallic femoral head and a metallic acetabular cup in a hip joint simulator. An electrical resistivity technique previously developed for engine tribology studies was used to detect the extent of surface separation throughout a cycle of dynamic loading simulating walking conditions. A metal-on-metal total joint replacement was tested in a single station of a ten-station hip joint simulator in the presence of five different lubricants. Two proteinaceous serum-based fluids of concentrations 25 and 100 per cent were used as well as three lubricants devoid of protein but of quite different viscosities. It was observed that surface separation developed with both the protein-based fluids during the swing phase of the articulation and that an equilibrium cyclic pattern of contact and separation was established after running the simulator for some minutes. Furthermore, there was at times some evidence of separation during the severe conditions encountered during the stance phase. Silicone fluid failed to promote surface separation, while water and the more viscous carboxymethylcellulose solution yielded only modest periods of separation during the swing phase. It was deduced from experimental and analytical features of the study that the mode of lubrication was mixed, with some periods of very effective surface separation and others of metal-to-metal contact. While the presence of protein was necessary for effective lubrication, the cyclic pattern of separation appeared to be determined by elastohydrodynamic action. The bond strength of the protein to the metals appeared to be weak. The partial film of lubricant between the boundary lubricating layers provided significant enhancement to the combined protective action in this mixed lubrication system. The simple, cheap and effective electrical resistivity technique has revealed important new information on the tribological conditions in metal-on-metal hip joints which determine friction and wear. It can readily be adopted on most forms of total joint simulators. The technique and the findings reported here further advance the development of criteria for lubricants to be used in laboratory studies of the performance of total replacement joints.

Novel "composite" materials using porous sintered stainless steel adherends mechanically "bonded" with synthetic elastomers

Artificial hip joints currently have a life span of 10-15 years because wear of the polymeric acetabular cup causes loosening of the femoral stem. Recent research has shown that compliant layers can extend the life of the joint to possibly 25 years or more by helping to maintain fluid film lubrication. The problem of &quot;bonding&quot; the compliant layer to a metallic cup was approached by manufacturing porous sintered stainless steel substrates with (1) a range of total porosity from 10 to 35%, and (2) graded structures, using a combination of different powder particle sizes and compaction pressures. An elastomeric polymer was &quot;bonded&quot; onto porous metal substrates to create cylindrical test pieces which were subjected to torsional loading. Substantial mechanical interlocking of the polymer in the interstices of the metallic substrates created a &quot;composite&quot; structure, preventing catastrophic polymeric fracture after interfacial failure. Thus the strain, load at failure and apparent energy of adhesion were considerably higher for porous substrates than for dense materials.

Failed instrumental delivery: how safe is the use of a second instrument?

An audit of failed instrumental deliveries was undertaken to assess the incidence of complications and the adequacy of documentation. When one instrument has failed to effect delivery, the use of a second instrument could in most cases be used to complete the delivery without harm to the mother or baby. However in a small but significant number of cases there are severe maternal or perinatal complications, and these could be the subject of litigation. This could be avoided by adequate pre-application assessment, standard conduct of instrumental delivery and full documentation. Inadequate documentation could be overcome by the use of a pro forma. Selective use of plastic and metal cups could reduce the incidence of failed attempts.

Les objets en métal du tombeau monumental d'Arslantepe de 3000 av. J.-C. (Malatya, Turquie)

The discovery of an exceptional royal tomb in the Early Bronze levels (3000 B.C.) at Arslantepe (Malatya, Turkey) sheds new light on the development of metallurgy in the Near East. Two skeletons, with metal diadems and pins, were found lying on top of the covering slabs. Inside the tomb lay one skeleton in a contracted position with numerous funerary gifts which included nine bronze spears, daggers, swords, axes, burins, pins and spirals. Gold and silver beads from a necklace were also found, together with a metal bowl and cup, numerous ceramic vases and one in alabaster. This material enables us to ascribe this tomb to a transitional phase between periods VIA and VIB in the Arslantepe internal sequence. A total of 75 metal objects were found. The weapons are made of a Cu-As-Ni alloy, while many of the objects, including a dagger, the diadems and some pins are made of an Ag-Cu alloy. The metal objects found in this tomb represent a unique collection on account of both their number and quality, the fact that they date from such an early period and, lastly, in view of the results of the analysis of the objects themselves, which demonstrate the presence of new alloys. These results may henceforth be used as a reference point for early metallurgy in eastern Anatolia.

Total hip replacement in presence of acetabular dysplasia type II according to the AAOS classification

Incorporation of the acetabular cup in ideal position in patients with a primary dysplastic acetabulum. Two thirds of the surface of the cup must be covered by bone. Joint replacement in patients with acetabular dysplasia type II according to the AAOS classification. Presence of acetabular dysplasia types I and III according to the AAOS classification. Radiographic measurement of the acetabular depth and width using templates. Supine, affected side of pelvis slightly elevated. General or spinal anaesthesia. Special set of instruments mandatory. Insertion of an acetabular cup through a lateral approach. Reaming of the acetabulum and filling of the defect under compression with a mixture of autogenous, morcellized bone from the resected femoral head and fibrin glue. Coverage of the transplanted bone with a pedicled capsular flap. Phlebitis prophylaxis. Walking with 2 forearm crutches on the first postoperative day. Removal of stitches after 10 days. Thereafter gradual increase of weight bearing (10 kg every second day, use a bathroom scale to check loading). Once full weight bearing and full muscle control have been reached, use of 1 crutch is allowed. Radiographic control after 6 weeks, 3,6 and 12 months and yearly thereafter. Perforation of the bony acetabulum. Fracture of the anterior or posterior acetabular rim. Thrombophlebitis, lung embolism, infection and/or periarticular ossification. Between 1986 and 1994 the technique has been used in 140 hips with congenital dysplasia (type II according to the AAOS classification) and secondary osteoarthritis. 132 hips were regularly assessed and the mean of follow-up was 6.2 years (1 to 9 years). The mean age of the mostly female patients was 48 years (28 to 62 years). Only porous surfaced metallic cups without cement were used. The following complications were observed: thrombophlebitis 1, superficial infection 1, transient paresis of the fibular nerve 1 and transient irritation of the femoral nerve 3 (see Table 2). Additional complications such as thigh pain, periarticular ossification and resorption of the bone graft are listed in Table 3. Complete bony incorporation of the bone grafts was seen in 122 hips. Resorption up to 8 mm occurred in the remaining 10 hips.