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PubMed1975

Acrylic cement stabilized joint replacements.

Surgical management of osteoarthritis, aseptic necrosis and rheumatoid arthritis has been revolutionized by the introduction of acrylic cement-stabilized joint surface replacement. Although single joint surface replacements have been employed extensively for more than half a century, total surface replacement operations with a wear-resistant high-density polyethylene and noncorrosive stainless steel stabilized by acrylic cement were introduced only a little more than 12 years ago. This evolved with Charnley's discovery of the high level of bone tolerance for acrylic cement. Acrylic cement made it possible mechanically to bond artificial joint surfaces to the bone ends and produce an insensitive Charcot-like functioning joint. A barium sulfate additive makes the cement radiopaque for visualizing the bone-cement interface. Barium sulfate additive also lowers the polymerization temperature and opens the polymer for influx of interstitial fluids. Antibiotics have also been added to the cement for prevention and treatment of infection of the surrounding tissues. In aged individuals with cardiovascular disease, the absorption of the acrylic monomer depresses cardiac output and produces hypotension for 2-5 minutes after impaction of acrylic cement into spongy bone. The hypotension has been minimized by cautious fluid replacement and maintenance of adequate blood volume before, during and after the operation. Approximately 30,000 total hip arthroplasties are performed in the United States annually in patients older than 50 years of age with fractured femoral head replacements, bilateral rheumatoid arthritis, old neglected congenital dislocations of the hip or osteonecrosis with and without osteoarthritis. The pain relief is more complete and the functional improvement more predictable than in any other previously recommended surgical operation for the purpose. For this reason, total hip arthroplasty has almost completely supplanted mold-arthroplasty, osteotomy, capsulotomy (hanging hip) and resection of the femoral head. Hemiarthroplasty in the form of femoral head replacement still is the procedure of choice in patients with fractures of the neck of the femur and a normal acetabular articular cartilage, irrespective of age. As a countermeasure against loosening of the prosthesis in patients with osteoporosis and a hollow proximal end of the femur, the stem can be stabilized with acrylic cement. A standard replaceable femoral head for subsequent conversion of femoral head replacement to total hip arthroplasty is an important consideration and presently is under investigation in several medical centers.(ABSTRACT TRUNCATED AT 400 WORDS)

Acrylates↗
PubMed1995

Chemical versus dual curing of resin inlay cements.

Dual-cure inlay resin cements polymerize both chemically and through light activation; however, clinically some aspects of the cement are not readily accessible to the light source. This study investigated the degree of cement hardening achieved through chemical curing only versus dual curing and the effect of inlay thickness on cement hardness. Disks 6 x 2.5 mm were prepared from seven commercially available cements. Eight specimens were prepared from each material; half of the specimens were cured chemically only, and the remainder were dual-cured. Knoop hardness measurements were then recorded at 1-hour, 1-day, and 1-week intervals. In addition, 24 specimens of the same dimensions were prepared from each cement. Twelve specimens were dual-cured through resin composite spacers of varying thicknesses (1 to 6 mm), and the others were cured through similar ceramic spacers, and hardness measurements were recorded. Multivariate analysis of variance revealed significant differences in hardness of chemically cured versus dual-cured specimens at the 5% level of significance for all examined cements. Significant differences were also found in the hardness of specimens dual cured through ceramic or resin composite spacers 2 to 3 mm in thickness or more versus those that were dual cured without spacer regardless of the spacer material. It is concluded that chemical curing alone was not sufficient to achieve maximum hardening of the examined cements. Cement hardness was significantly reduced when inlay thickness was 2 to 3 mm or more.

Analysis of Variance↗
PubMed1997

Adhesion of glass ionomer cement to a ceramometal alloy.

STATEMENT OF PROBLEM: Glass ionomer cements can be used for restoring minor caries lesions, sealing an endodontic access, and repairing defective margins of inlay-onlay restorations. Little information is available on the adhesion between ceramometal alloys and various types of glass ionomer cements. PURPOSE: The aim of this study was to determine whether the adhesion of glass ionomer cement to the surface of a ceramometal alloy could be enhanced with pretreatment of the alloy surface. MATERIAL AND METHODS: Six groups of five specimens were either ground with a diamond bur, sandblasted with aluminum oxide, or ground with a silicon-carbide stone before bonding to either conventional glass ionomer or resin-glass ionomer cements. Resistance to bond failure was tested with a three-point loading test. RESULTS: The results revealed that the greatest resistance to bond failure was obtained by the resin-glass ionomer cement to the sandblasted alloy surface and the least resistance by the glass ionomer cement to the diamond ground alloy surface (p < 0.001). Both the type of glass ionomer cement (p = 0.002) and the type of mechanical treatment (p = 0.001) affected the resistance to bond failure. CONCLUSIONS: This study suggests that pretreatment of alloy surfaces with a sandblasting device may be recommended when repairing marginal defects of alloy restorations with glass ionomers. Resin-glass ionomer cements seem to give better adhesion than conventional glass ionomer cements do.

Adhesiveness↗
PubMed1994

Evaluation of an apatite cement as a root end filling material.

A self-setting apatite cement, EBA cement, and amalgam with varnish were tested for root end sealing ability using a fluid filtration and dye technique. Single-rooted human teeth were prepared in vitro to receive root end fillings. Experimental groups were amalgam with two layers of varnish, EBA cement with dry cavity, EBA cement within a wet cavity, apatite cement within a dry cavity, and apatite cement within a wet cavity. Fluid filtration measurements were made at 6, 24, and 7 days, and 1 and 3 months. Each specimen was also subjected to a dye leakage test using Procion Green dye at 3 months. Results indicated that apatite cement provided a comparable seal to amalgam and EBA cement. This finding, in conjunction with its excellent biocompatibility, suggests that apatite cement is an acceptable alternative to present-day root end filling materials.

Aluminum Oxide↗
PubMed2001

Influence of resin cement viscosity on microleakage of ceramic inlays.

OBJECTIVES: The aim of the present investigation was to evaluate the effect of the different viscosities of two resin luting cements on microleakage of ceramic inlays at dentinal margins. The effect of the width of the space between inlay and tooth, on the quality of the marginal seal was also investigated. METHODS: Mesial and distal class V cavities were prepared in 48 extracted third molars. The incisal margins of the cavities were in enamel and the cervical margins in dentin. Subsequently, Empress inlays with different cervical margin gap dimensions were fabricated. The mean cervical gap dimensions in the respective groups were as follows: group 1 (27 microm); group 2 (232 microm); group 3 (406 microm). Half the inlays in each group (16) were cemented with a low viscous resin luting cement, and half (16) with a highly viscous resin luting cement. The teeth were subjected to occlusal loading with synchronized thermal cycling in a masticatory simulator. Then, the specimens were immersed in basic fuchsin solution, and dye penetration along the cavity walls was measured. In addition, marginal adaptation was analyzed in the SEM at baseline and after loading, using a replica technique. RESULTS: With regard to dye penetration at dentinal margins, the highly viscous cement performed statistically significantly better at dentin/composite margins than the low viscous cement (p=0.0158). These findings are supported by SEM analysis. SIGNIFICANCE: It is assumed that polymerization stress within the luting cement could not be completely compensated for by larger luting spaces. Highly viscous luting cements are recommended for cementing class V inlays in larger luting spaces.

Aluminum Silicates↗
PubMed2001

Release profile of antimicrobial agents from alpha-tricalcium phosphate cement.

A new method for treating carious dentine with alpha-tricalcium phosphate (alpha-TCP) dental cement containing antimicrobial agents has been recently introduced. However, the release behavior of antimicrobial agents from this cement has not yet been clarified. The aim of this study is therefore to examine the release profile of the antimicrobial agents from the alpha-TCP cement. Three kinds of antimicrobial agents (metronidazole, cefaclor and ciprofloxacin) were added to two commercially available alpha-TCP cements (new apatite liner type I and type II). The set cements were then immersed in water at 37 degrees C and the released antimicrobial agents and Ca ion were determined at regular intervals for three months. In addition, scanning electron microscopic observations were conducted before and after immersion for three months. The release profile of the cements containing antimicrobial agents varied depending on the types of antimicrobial agents. The incorporation of antimicrobial agents affected the setting reaction of the cements. The release behavior of the drugs also varied depending on the types of the cements. The differences in the release profile between type I and type II cements reflected the structures and compositions of their matrices.

Anti-Infective Agents↗
PubMed2001

Interactions between glass ionomer cement and alkali metal fluoride solutions: the effect of different cations.

This study examines the effect of different cations in equimolar alkali metal fluoride solutions on their interactions with glass ionomer cements. Uptake of both fluoride and cation were measured together with change in solution pH and morphological changes in the cement surface. Two cements were used; AH2, a dental restorative cement containing both fluorine and alkali metal (Na) as glass components and LG30, which contained neither. Discs of cement 1 x 10 mm were set in moulds at 37 degrees C for 1 h then, stored in water for 3 days at 37 degrees C. Discs in each test group (N = 5) were immersed in 10 ml of solutions of either NaF, KF, or RbF, all containing 900ppm F, control discs were stored in water, all at 37 degrees C for 24h. Solutions were analysed for F- by ISE potentiometry, Na+ by the same technique and K+ and Rb+ were analysed by atomic absorption spectrometry. Uptake was obtained by difference between solution used for immersion and the control solution. Solution pH was measured potentiometrically. The surface roughness of the discs was measured by linear stylus profilometry. Fluoride ion uptakes for AH2 were 451 micromol/g NaF, 378 KF, and 318 RbF. The comparable figures for LG30 were 202, 161, and 159. Differences between cements were all statistically significant and also between solutions pairings except for the KF/LG30 vs. RbF/LG30. Uptake of cations was equimolar for AH2/ NaF, AH2/RbF and LG30/KF but M+:F- ratios were significantly above unity for AH2/KF and LG30/NaF and significantly below unity for LG30/RbF. The pH changes were all positive and were significantly higher for AH2 than LG30 and for RbF compared to the other fluoride solutions for each cement (probably because of its lower initial pH). The final pH of all solutions were less than I pH unit from neutral (pH7). The AH2 cement test discs all showed significant increase in roughness (Ra) compared to control discs stored in water whereas the LG30 discs showed no such difference. Regression analysis showed a significant positive correlation between fluoride uptake and Ra. It was concluded that changing the alkali metal cation influenced all four variables examined (F- uptake, M+ uptake, pH change and extent of cement surface roughening).

Cations↗
PubMed2002

In vitro testing of the potential for orthopedic bone cements to cause apoptosis of osteoblast-like cells.

The purpose of this study was to investigate in vitro the apoptosis- and/or necrosis-inducing potential of polymethylmethacrylate (PMMA)-based bone cements for prosthetic surgery. Four bone cements widely used in orthopedics were tested as extracts onto osteoblast-like MG-63 cells and for comparison, HL-60 cells, which are remarkably sensitive to apoptotic stimuli. Neutral red uptake (NRU) was used to measure cell viability while Hoechst 33258 staining was used to detect DNA content. Apoptosis was characterized using a BrdU-based ELISA assay for DNA fragmentation and examined by fluorescence microscopy using acridine orange and propidium iodide staining of nuclei. The generation of reactive oxygen species (ROS), which could mediate apoptosis, was verified using dichlorofluorescein-diacetate (DCFH-DA) oxidation to DCF. After 24 h of challenge of the cells with the four cement extracts, the viability of either MG-63 or HL-60 cells was found to be unaltered, as recorded by NRU. Apoptotic cell death was induced by three cements in HL-60, whereas MG-63 cells were significantly affected by the four cements tested: the finding of DNA fragments both in the cytoplasm and supernatants of MG-63 after 24 h demonstrated that these cells underwent late-apoptosis secondary necrosis. Fluorescent staining of the nuclei confirmed the results obtained with the ELISA test. Oxygen free radicals were elicited by two cements in HL-60 cells, while MG-63 did not generate ROS in response to cements. This study helps to gain more insight into the mechanism of cell death induced by PMMA-based cements and suggests apoptosis of osteoblasts as a part of the tissue reaction around cemented prostheses.

Apoptosis↗
PubMed2001

Mixed-mode failure response of the cement-bone interface.

Mechanical failure of the cement-bone interface can contribute to clinical loosening of cemented total hip replacements. The conditions that cause loosening are poorly understood, in part, due to a lack of information on the mechanical behavior of the cement bone interface. The purpose of this study was to determine the mechanical behavior of the cement-bone interface due to mixed-mode (combined tension and shear) loading and to develop a failure model for the cement bone interface. Laboratory tests of machined cement-bone test specimens were performed with mixed-mode loading conditions (loading angles of 22.5 degrees, 45 degrees, and 67.5 degrees) to determine the mechanical response in the pre-yield and post-yield state. After accounting for the quantity of interdigitated bone as a covariate, the mixed-mode data were combined with previous tension (0 degrees) and shear data (90 degrees) to develop a failure model for the cement bone interface. The strength of the interface was positively correlated with the quantity of interdigitated bone (r2 = 0.70, 0.53, 0.49, for 22.5 degrees, 45 degrees, and 67.5 degrees, respectively). There was a significant increase in failure strength (P < 0.001) with increasing mixed-mode angle. When all data were incorporated into an elliptical failure criterion, the average error between the actual and predicted strength was 33%. These results can now be incorporated into constitutive models of the cement bone interface to determine the initiation and progression of interface failure in cemented total hip replacements.

Aged↗
PubMed2004

Cements from nanocrystalline hydroxyapatite.

Calcium phosphate cements are used as bone substitute materials because they may be moulded to fill a void or defect in bone and are osteoconductive. Although apatite cements are stronger than brushite cements, they are potentially less resorbable in vivo. Brushite cements are three-component systems whereby phosphate ions and water react with a soluble calcium phosphate to form brushite (CaHPO4 x 2H2O). Previously reported brushite cement formulations set following the mixture of a calcium phosphate, such as beta-tricalcium phosphate (beta-TCP), with an acidic component such as H3PO4 or monocalcium phosphate monohydrate (MCPM). Due to its low solubility, hydroxyapatite (HA) is yet to be reported as a reactive component in calcium phosphate cement systems. Here we report a new cement system setting to form a matrix consisting predominantly of brushite following the mixture of phosphoric acid with nanocrystalline HA. As a result of the relative ease with which ionic substitutions may be made in apatite this route may offer a novel way to control cement composition or setting characteristics. Since kinetic solubility is dependent on particle size and precipitation temperature is known to affect precipitated HA crystal size, the phase composition and mechanical properties of cements made from HA precipitated at temperatures between 4 and 60 degrees C were investigated.

Bone Cements↗
PubMed2002

Survey of current cementing techniques in total knee replacement.

BACKGROUND: Current techniques in total knee replacement (TKR) vary greatly. Cementing techniques in TKR are no exception. Identification of current trends would aid ongoing research into future developments. METHODS: A questionnaire was sent to all orthopaedic surgeons in Queensland, Australia. A range of factors influencing cementing techniques for the tibial plateau were investigated. RESULTS: Eighty-five percent of questionnaires were returned. Ninety-one percent of surgeons regularly cement the tibial plateau, 90% use some form of lavage prior to cement application, 95% of surgeons apply cement by hand only. Techniques aimed at increasing cement penetration (cement gun, intraosseous suction) are used infrequently. CONCLUSIONS: In contrast to total hip replacement, measures are not often taken to ensure that there is penetration of cement or a complete cement mantle into the tibial plateau in TKR. This may be because of a perceived lack of evidence in modern literature. This study also illustrates the wide variation in technique in a relatively common orthopaedic operation.

Arthroplasty, Replacement, Knee↗
PubMed2001

Boneloc bone-cement: experience in hip arthroplasty during a 3-year period.

Polymethyl methacrylate (PMMA) bone-cement was introduced in the 1960s for fixation of total hip arthroplasty replacement components. Long-term results of cement fixation for hip and knee arthroplasty have been extremely good. Although the use of PMMA bone-cement has enabled long-term survival of joint arthroplasty implants, there has been concern about aseptic loosening. This concern led to the introduction of Boneloc bone-cement (Biomet, Warsaw, IN) in the early 1990s. It was hoped that with the improved physical and chemical characteristics of Boneloc, there would be less aseptic loosening in the long-term. A clinical trial was conducted to evaluate Boneloc bone-cement in cementing the femoral component of the Bimetric total hip arthroplasty prosthesis in 33 hips in 32 patients. On follow-up, 7 stems (24%) developed definite loosening, and 3 stems (10%) were possibly loose. Of the 7 definite loose stems, 5 (17%) were revised because of increasing pain or progressive loosening. Despite the biologic advantages of Boneloc, this study suggests that the chemicals substituted in Boneloc bone-cement led to an alteration in its mechanical properties. These properties proved to be inferior to conventional PMMA bone-cement. There is possible time-dependent deterioration of mechanical properties leading to early aseptic loosening. The conventional PMMA bone-cement has stood the test of time. Research and experimental studies should continue to improve the mechanical properties of Boneloc before further human trials.

Arthroplasty, Replacement, Hip↗
PubMedDate not supplied

[Effect of femoral intramedullary irrigation on periprosthetic cement distribution: jet lavage versus syringe lavage].

INTRODUCTION: The purpose of this experimental study was to determine quantitatively the cement penetration into periprosthetic femoral bone by Icomparing the use of jet-lavage with the conventional syringe irrigation. METHODS: 10 pairs of fresh-frozen human cadaver femora were used for cemented stem implantation, The left femora were irrigated with a syringe device, the right femora with a jet-lavage system. After implantation, all femora were cut into 5-mm slices from proximal to distal with a diamond saw. The scanned slices were analysed using an image processing system which provided a discrimination between implant, cement, and bone as well as an exact determination of the cement area. RESULTS: In all 10 femora, a recognizable improvement of the cement penetration into the periprosthetic bone was demonstrated using the jet-lavage. In the proximal part, the mean cement penetration was 8.6% higher in the jet-lavage group than in the syringe device group. An equivalent tendency towards the jet-lavage pretreated femora was seen in the middle part with 8.7% on average mean and in the distal part with 6.4% on average. Also, when subdividing the periprosthetic area into 4 quadrants, a significant improvement of the cement penetration was found with the exception of the ventro-medial region. CONCLUSION: Cement distribution and penetration is improved using the jet-lavage technique for cleaning the medullary canal of the femur. Therefore, the jet-lavage should be used as a standard procedure in clinical cementing techniques.

Arthroplasty, Replacement, Hip↗
PubMed2002

The dynamic volume changes of polymerising polymethyl methacrylate bone cement.

The Swedish hip register found an increased risk of early revision of vacuum-mixed cemented total hip replacements. The influence of cement mixing technique on the dynamic volume change in polymerising PMMA is not well understood and may be relevant to this observation. Applying Archimedes' principle, we have investigated the dynamic volume changes in polymerising cement and determined the influence of mixing technique. All specimens showed an overall volume reduction: hand-mixed 3.4% and vacuum-mixed 6.0%. Regression analysis of sectional porosity and volume reduction showed a highly significant relationship. Hand-mixed porous cement showed a transient volume increase before solidification. However, vacuum-mixed cement showed a progressive volume reduction throughout polymerisation. Transient expansion of porous cement occurs at the critical time of micro-interlock formation, possibly improving fixation. Conversely, progressive volume reduction of vacuum-mixed cement throughout the formation of interlock may damage fixation. Stable fixation of vacuum-mixed cement may depend on additional techniques to offset the altered volumetric behaviour of vacuum-mixed cement.

Bone Cements↗
PubMed2006

The effect of low-viscosity cement on mantle morphology and femoral stem micromotion: a cadaver model with simulated blood flow.

BACKGROUND: Limited data exist on the performance of low-viscosity cement in clinically realistic cadaver models. METHODS: Paired stem/cement/femur constructs were generated with low-viscosity and standard-viscosity cements. The constructs were created and tested under simulated in vivo conditions, for which novel techniques were developed during this study. Mantle function was quantified by stem/cortex micromotions over 105cycles of "stair-climbing". Mantle morphology was determined from transverse sections. RESULTS: Penetration of low-viscosity cement was greater proximally but less distally (p = 0.02). Low-viscosity cement resulted in more stem retroversion (p = 0.04), but there was no difference in subsidence (p = 0.4). Low-viscosity cement mantles had greater fractions of non-apposed interface (p = 0.006). Fraction of non-apposed interface predicted stem retroversion (R2 = 0.64, p = 0.002). INTERPRETATION: Low-viscosity cement resulted in inferior cement mantles. Early micromotion was reduced by better interface apposition. The greater stem retroversion of low-viscosity cement would probably lead to higher revision rates. Early stem migration is due to interface non-apposition. Techniques should be developed to reduce non-apposition of cemented interfaces.

Aged↗
PubMed2003

Reconstruction of the immature craniofacial skeleton with a carbonated calcium phosphate bone cement: interaction with bioresorbable mesh.

Calcium phosphate cements have been recently introduced for use in craniofacial reconstruction. In the clinical setting, however, pulsations of the underlying brain and dura may interfere with the crystallization of these cements, thereby rendering their use in cranioplasty problematic. To circumvent such problems, many clinicians have interposed synthetic resorbable plates or mesh between the dura and the cement. At the present time, however, little is known about the influence of such materials or their breakdown products on the fate of calcium phosphate cements. The specific aim of this project was to evaluate the biocompatibility, osteoconductivity, and remodeling capacity of a calcium phosphate cement after implantation into experimental calvarial defects when combined with a resorbable mesh underlay. Four 10-mm diameter full-thickness calvarial defects (two frontal, two parietal) were created in each of six 3-week-old Yorkshire pigs. The defects were treated as follows: 1) empty control, 2) macroporous polylactic acid (70/30 L/DL polylactic acid [PLA]) mesh, 3) Norian CRS calcium phosphate cement, and 4) Norian CRS over PLA mesh underlay. Animals were divided into two groups. Half of the animals were killed 30 days after surgery, and half were killed 180 days after surgery, and the graft recipient sites were examined histologically. At 30 days, minimal bone ingrowth was observed in untreated calvarial defects or in those that were treated with PLA plates alone. Defects treated with the cement alone demonstrated a modest amount of new woven bone deposition, primarily at the periphery of the implants. Defects treated with calcium phosphate cement over PLA mesh underlays were characterized by remodeling and woven bone deposition at 30 days, with complete or near-complete osseous bridging of the ectocranial implant surfaces. Progressive bone ingrowth was noted in all defects at 180 days, with near-complete replacement of all Norian CRS implants by host bone. The PLA mesh remained incompletely resorbed at 180 days. No inflammatory response to the implants was observed at either time point. Calcium phosphate cement may be safely used for craniofacial reconstruction in the presence of PLA implants without compromise to its biocompatibility, osteoconductivity, or remodeling capacity.

Absorbable Implants↗
PubMed1998

Proximal and distal femoral centralizers in modern cemented hip arthroplasty.

Third generation cementing techniques using intramedullary restrictors, low porosity cement with pressurization, lavage, and cement-stem bond enhancement do not prevent implant malalignment and inadequate cement mantle thickness. This has led to the development of modular proximal and distal centralizers to control the alignment of the femoral component and maintain an adequate thickness of the cement, thereby theoretically decreasing the rate of aseptic loosening. A retrospective analysis was performed of 100 primary cemented centralized femoral components. At an average followup of 5.7 years (range, 4-8 years), the average Harris Hip Score was 90. There were no cases of aseptic loosening, osteolysis, or impending failure. Ninety-one percent of femoral stems were implanted with satisfactory alignment with an optimal cement thickness. However, six distal centralizers and one proximal centralizer fractured at the time of insertion and voids frequently were seen in and around the distal centralizer. Although centralizers improve prosthesis alignment and cement mantle thickness, the long term effects of centralizer fracture and distal cement voids need to be observed to determine if centralizers improve previous implant survival.

Aged↗
PubMed1998

Pressurization and centralization enhance the quality and reproducibility of cement mantles.

Cementing technique has a profound influence on the incidence of aseptic loosening of total hip replacements. Two specific measures that seem to have the greatest impact on the longevity of cemented femoral stems are pressurization of cement and control of mantle thickness, typically through the use of modular centralizing devices attached to the tip of the prosthesis. Two laboratory studies are presented that examine the success of these measures in clinical practice. In the first study, the performance of five designs of intramedullary plugs in resisting migration during pressurization of cement was evaluated in human anatomic specimen femurs. Profound differences were observed between the performance of the different plug designs. In canals larger than 12 to 14 mm, most commercial devices failed to resist pressures greater than 30 to 40 pounds per square inch. Overall, it was estimated that between 6% to 76% of these devices would fail to resist cement pressures of 50 pounds per square inch in clinical practice. The second study examined the role of distal centralizers in the accumulation of air bubbles around the distal tip of the prosthesis during insertion of the stem into the femur. Acrylic replicas of a femoral stem were implanted in cavities simulating the femoral canal. Colored dyes, present within the cement, revealed the complex patterns of cement flow. It was shown that cement, dragged from the top of the femur, forms a thin layer that covers the entire surface of the prosthesis and the distal centralizer. Significant voids were present behind the trailing edges of the distal centralizer in 42% of the cases examined. These studies show that improvements in intramedullary plugs and stem centralizers are needed to increase the reproducibility of cement technique in total hip replacement.

Arthroplasty, Replacement, Hip↗