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Bone & Joint Open
Vol. 4, Issue 7 | Pages 507 - 515
6 Jul 2023
Jørgensen PB Jakobsen SS Vainorius D Homilius M Hansen TB Stilling M

Aims

The Exeter short stem was designed for patients with Dorr type A femora and short-term results are promising. The aim of this study was to evaluate the minimum five-year stem migration pattern of Exeter short stems in comparison with Exeter standard stems.

Methods

In this case-control study, 25 patients (22 female) at mean age of 78 years (70 to 89) received cemented Exeter short stem (case group). Cases were selected based on Dorr type A femora and matched first by Dorr type A and then age to a control cohort of 21 patients (11 female) at mean age of 74 years (70 to 89) who received with cemented Exeter standard stems (control group). Preoperatively, all patients had primary hip osteoarthritis and no osteoporosis as confirmed by dual X-ray absorptiometry scanning. Patients were followed with radiostereometry for evaluation of stem migration (primary endpoint), evaluation of cement quality, and Oxford Hip Score. Measurements were taken preoperatively, and at three, 12, and 24 months and a minimum five-year follow-up.


Bone & Joint Research
Vol. 11, Issue 5 | Pages 270 - 277
6 May 2022
Takegami Y Seki T Osawa Y Imagama S

Aims

Periprosthetic hip fractures (PPFs) after total hip arthroplasty are difficult to treat. Therefore, it is important to identify modifiable risk factors such as stem selection to reduce the occurrence of PPFs. This study aimed to clarify differences in fracture torque, surface strain, and fracture type analysis between three different types of cemented stems.

Methods

We conducted biomechanical testing of bone analogues using six cemented stems of three different types: collarless polished tapered (CPT) stem, Versys Advocate (Versys) stem, and Charnley-Marcel-Kerboull (CMK) stem. Experienced surgeons implanted each of these types of stems into six bone analogues, and the analogues were compressed and internally rotated until failure. Torque to fracture and fracture type were recorded. We also measured surface strain distribution using triaxial rosettes.


The Bone & Joint Journal
Vol. 103-B, Issue 6 Supple A | Pages 51 - 58
1 Jun 2021
Yang J Heckmann ND Nahhas CR Salzano MB Ruzich GP Jacobs JJ Paprosky WG Rosenberg AG Nam D

Aims

Recent total knee arthroplasty (TKA) designs have featured more anatomical morphologies and shorter tibial keels. However, several reports have raised concerns about the impact of these modifications on implant longevity. The aim of this study was to report the early performance of a modern, cemented TKA design.

Methods

All patients who received a primary, cemented TKA between 2012 and 2017 with a minimum two-year follow-up were included. The implant investigated features an asymmetrical tibial baseplate and shortened keel. Patient demographic details, Knee Society Scores (KSS), component alignment, and the presence of radiolucent lines at final follow-up were recorded. Kaplan-Meier analyses were performed to estimate survivorship.


The Bone & Joint Journal
Vol. 103-B, Issue 6 Supple A | Pages 137 - 144
1 Jun 2021
Lachiewicz PF Steele JR Wellman SS

Aims

To establish our early clinical results of a new total knee arthroplasty (TKA) tibial component introduced in 2013 and compare it to other designs in use at our hospital during the same period.

Methods

This is a retrospective study of 166 (154 patients) consecutive cemented, fixed bearing, posterior-stabilized (PS) TKAs (ATTUNE) at one hospital performed by five surgeons. These were compared with a reference cohort of 511 knees (470 patients) of other designs (seven manufacturers) performed at the same hospital by the same surgeons. There were no significant differences in age, sex, BMI, or follow-up times between the two cohorts. The primary outcome was revision performed or pending.


The Bone & Joint Journal
Vol. 101-B, Issue 11 | Pages 1331 - 1347
1 Nov 2019
Jameson SS Asaad A Diament M Kasim A Bigirumurame T Baker P Mason J Partington P Reed M

Aims

Antibiotic-loaded bone cements (ALBCs) may offer early protection against the formation of bacterial biofilm after joint arthroplasty. Use in hip arthroplasty is widely accepted, but there is a lack of evidence in total knee arthroplasty (TKA). The objective of this study was to evaluate the use of ALBC in a large population of TKA patients.

Materials and Methods

Data from the National Joint Registry (NJR) of England and Wales were obtained for all primary cemented TKAs between March 2003 and July 2016. Patient, implant, and surgical variables were analyzed. Cox proportional hazards models were used to assess the influence of ALBC on risk of revision. Body mass index (BMI) data were available in a subset of patients.


Orthopaedic Proceedings
Vol. 99-B, Issue SUPP_8 | Pages 53 - 53
1 Apr 2017
Goubran A McHale S Steinlechner C
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Background. Aseptic loosening of cemented femoral stems results from migration of wear particles along the bone-cement interface, producing a foreign body reaction. After cement insertion, blood back pressure can disrupt the bone-cement interface, enabling this spread of wear particles. Our study investigates whether altering timing and speed of stem insertion can reduce this risk. Methods. We inserted mock “C-Stem” femoral components (De Puy-Synthes), using Smartset HV cement (De Puy-Synthes) into artificial femora, fitted with proximal and distal pressure transducers. Cement insertion began two, three or four minutes after mixing. Cement pressures were then allowed to settle for one minute and the stems were then inserted over durations of 25, 60 or 90 seconds. Results. Quicker insertion led to high peak pressures; however insertion over 90 seconds at 4 and 5 minutes achieved more sustained pressures above blood back pressure. Slower insertion particularly improved proximal pressurisation. Furthermore when the stem was inserted over 90 seconds at 5 minutes then the cement pressures remained high after full insertion of the stem. Conclusions. Commonly, femoral stems are inserted rapidly. Our study demonstrates that by inserting the femoral stem more slowly, cement pressure can be maintained above blood back pressure for longer. We believe that after slower stem insertion, the higher cement viscosity enables the surgeon to maintain cement pressure, via the stem, sufficient to resist blood back pressure without inadvertently over inserting the stem. This safe and simple modification of cementing technique generates higher and more sustained cement pressures. Level of evidence. 3. Disclosures. Depuy-Synthes kindly provided the equipment used in the study. None of the authors received any payment or other benefits


Orthopaedic Proceedings
Vol. 98-B, Issue SUPP_8 | Pages 53 - 53
1 May 2016
Itayem R Lundberg A Arndt A
Full Access

Introduction

While fixation on the acetabular side in resurfacing implants has been uncemented, the femoral component is usually cemented. The most common causes for early revision in hip resurfacing are femoral head and or neck fractures and aseptic loosening of the femoral component. Later failures appear to be more related to adverse soft-tissue reactions due to metal wear. Little is known about the effect of cementing techniques on the clinical outcome in hip resurfacing, since retrieval analysis of failed hip resurfacing show large variations. Two cementing techniques have dominated. The indirect low viscosity (LV) technique as for the Birmingham Hip resurfacing (BHR) system and the direct high viscosity (HV) technique as for the Articular Surface replacement (ASR) system. The ASR was withdrawn from the market in 2010 due to inferior short and midterm clinical outcome. This study presents an in vitro experiment on the cement mantle parameters and penetration into ASR resurfaced femoral heads comparing both techniques.

Methods

Five sets of paried frozen cadavar femura (3 male, 2 female) were used in the study. The study was approved by ethics committee. Plastic ASR replicas (DePuy, Leeds, UK), femoral head size 47Ø were used. The LV technique was used for the right femora (Group A, fig. 1 and 3) while the HV technigue was used for the left femora (Group B. Fig 2 and 4). The speciments were cut into quadrants. An initiial visual, qualitative evaluation was followed by CT analysis of cement mantle thickness and cement penetration into bone.


The Bone & Joint Journal
Vol. 98-B, Issue 3 | Pages 307 - 312
1 Mar 2016
Maggs JL Smeatham A Whitehouse SL Charity J Timperley AJ Gie GA

Aims

We report on the outcome of the Exeter Contemporary flanged cemented all-polyethylene acetabular component with a mean follow-up of 12 years (10 to 13.9). This study reviewed 203 hips in 194 patients. 129 hips in 122 patients are still in situ; 66 hips in 64 patients were in patients who died before ten years, and eight hips (eight patients) were revised. Clinical outcome scores were available for 108 hips (104 patients) and radiographs for 103 hips (100 patients).

Patients and Methods

A retrospective review was undertaken of a consecutive series of 203 routine primary cemented total hip arthroplasties (THA) in 194 patients.


Orthopaedic Proceedings
Vol. 95-B, Issue SUPP_34 | Pages 510 - 510
1 Dec 2013
Rodriguez L Rodrigues DB
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Acrylic bone cements are used rather extensively in orthopedic and spinal applications. The incorporation of calcium phosphate additives to bone cements, to induce osteoconductivity, have typically resulted in increased cement viscosity, decreased handling, and detrimental effects of the mechanical performance of the cement. Additionally, bioactive bone cements are offered at a premium cost, which limits clinical use of these materials. The goal of this study was to examine and characterize an alternative two-solution poly (methyl Methacrylate) (PMMA) bone cement (referred to as TSBC), after incorporation of several calcium phosphate additives and antimicrobials. These bioactive and antimicrobial two-solution cements were designed to have adjustable properties that meet specific requirements of orthopedic applications. The addition of a bioactive agent would lead to increased levels of bone reformation after surgery, while an antibiotic within the cement would decrease the ability for pathogens to grow in the interface between the bone and new implant. TSBC is a pre-mixed bone cement that exhibits a combination of attractive properties including high strength, adjustable viscosity, adequate exothermal properties, as well as offering the possibility of using the same batch multiple times. The addition of antibiotics has not been previously explored in two-solution bone cements. Therefore, it is desirable to induce antibacterial activity with this formulation. Hydroxyapatite (Ca5(PO4)3(OH)), Brushite (CaHPO4•2H2O), and Tricalcium Phosphate (Ca3(PO4)2)(TCP) were incorporated into the TSBC in varying concentrations (25 and 50 wt%), and the rheological characteristics were examined to verify the feasibility of adding high concentrations of fillers to this cement formulation. Results demonstrated that unlike commercial powder-liquid formulations, calcium phosphate additives in TSBC do not detrimentally affect handling and the rheological properties of the material, while also providing maintenance of cement strength and other physical properties. TSBC material spends a dramatically increased amount of time in the swelling phase, as compared to powder-liquid formulations and thus is better suited to incorporate additives fully into its polymer matrix. Current two-solution bone cements do not contain any osteoconductive or antimicrobial agents. This study investigated the effects of addition of these bioactive agents in the physical and mechanical properties of the cement. Cement porosity was investigated to ensure that the porous nature of the bioactive cement does not damage the mechanical stability of the material. Further imaging will be conducted to demonstrate the improved osteointegration of these bioactive cement with osteoblasts (Figure 1). Degradation studies have been conducted to validate the biodegradable properties of the bioactive components and antibiotics release profile. It is further hypothesized that the degradation time will correlate to the antimicrobial activity. As the cement is replaced with natural bone, more and more antimicrobial will become exposed to the physiologic environment causing a continuous antimicrobial release as the material is partially replaced with new bone over time. Antimicrobial effectiveness and antimicrobial release studies are under-way to illustrate the cements ability to restrict growth at the cement surface, as well as show the antimicrobial release profile over time


The Journal of Bone & Joint Surgery British Volume
Vol. 94-B, Issue 12 | Pages 1611 - 1617
1 Dec 2012
Jameson SS Baker PN Mason J Gregg PJ Brewster N Deehan DJ Reed MR

Despite excellent results, the use of cemented total hip replacement (THR) is declining. This retrospective cohort study records survival time to revision following primary cemented THR using the most common combination of components that accounted for almost a quarter of all cemented THRs, exploring risk factors independently associated with failure. All patients with osteoarthritis who had an Exeter V40/Contemporary THR (Stryker) implanted before 31 December 2010 and recorded in the National Joint Registry for England and Wales were included in the analysis. Cox’s proportional hazard models were used to analyse the extent to which risk of revision was related to patient, surgeon and implant covariates, with a significance threshold of p < 0.01. A total of 34 721 THRs were included in the study. The overall seven-year rate of revision for any reason was 1.70% (99% confidence interval (CI) 1.28 to 2.12). In the final adjusted model the risk of revision was significantly higher in THRs with the Contemporary hooded component (hazard ratio (HR) 1.88, p < 0.001) than with the flanged version, and in smaller head sizes (< 28 mm) compared with 28 mm diameter heads (HR 1.50, p = 0.005). The seven-year revision rate was 1.16% (99% CI 0.69 to 1.63) with a 28 mm diameter head and flanged component. The overall risk of revision was independent of age, gender, American Society of Anesthesiologists grade, body mass index, surgeon volume, surgical approach, brand of cement/presence of antibiotic, femoral head material (stainless steel/alumina) and stem taper size/offset. However, the risk of revision for dislocation was significantly higher with a ‘plus’ offset head (HR 2.05, p = 0.003) and a hooded acetabular component (HR 2.34, p < 0.001).

In summary, we found that there were significant differences in failure between different designs of acetabular component and sizes of femoral head after adjustment for a range of covariates.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXXVI | Pages 45 - 45
1 Aug 2012
Craig J Buchanan F O'Hara R Dunne N
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Vertebroplasty is a minimal invasive surgical procedure for treatment of vertebral compressive fractures, whereby cement is injected percutaneously into a vertebral body. Cement viscosity is believed to influence injectability, cement wash-out and leakage. Altering the liquid to powder ratio can affect the viscosity, level of cohesion and extent cement fill within the vertebral body and the ultimately strength and stiffness of the cement-vertebra composite. The association of these combined factors remains unclear. The aim of this study was to determine the relationship between cement viscosity and the potential augmentation of strength and stiffness in a model simulating in-vitro prophylactic vertebroplasty of osteoporotic vertebral bodies. Samples of synthetic bone (Sawbone) representing osteoporotic bone were manually injected with 1mL of calcium phosphate cement using a 11G cannulated needle. Calcium phosphate cement was produced by mixing alpha-tricalcium phosphate, calcium carbonate and hydroxyapatite with an aqueous solution of 5 wt% disodium hydrogen phosphate. Three liquid to powder ratio (LPR) representing different viscosity levels were used; i.e. 0.5mL/g (low viscosity), 0.45mL/g (medium viscosity) and 0.35mL/g (high viscosity). Cement filled samples were then placed in an oven (37oC) for 20 min and then immersed in Ringer's solution (37oC) for 3 days. Samples of synthetic bone without cement injection were used as controls. Potential for leakage and wash-out was determined using gravimetric analysis. Extent of cement fill was determined using computer tomography (CT). Samples were tested under axial compression at a rate of 1 mm/min and the strength and stiffness determined. Statistical significance against controls was determined using a one-way analysis of variance (p<0.05). Low viscosity cement showed more cement leakage (p=0.512) and increased cement wash-out after 3 days in Ringer's solution (p=0.476). Qualitative assessment of cement fill within the vertebral body using CT imaging supported the wash-out results. The strength (p<0.05-0.01) and stiffness (p<0.01) of samples significantly increased by cement injection in comparison to control, the extent of this increase was greater with increasing cement viscosity. Linear correlation analysis showed a definite association between the mechanical properties and viscosity of injected cement and was dependent on the amount of cement retained within the synthetic bone post-setting


Orthopaedic Proceedings
Vol. 93-B, Issue SUPP_II | Pages 142 - 142
1 May 2011
Nieuwenhuijse M Muijs S Van Erkel A Dijkstra S
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Study Design: Comparative, prospective follow-up study. Objective: Comparison of outcome between patients treated with Percutaneous VertebroPlasty (PVP) using low viscosity PolyMethylMetAcrylate (PMMA) bone cement and patients treated with PVP using medium viscosity PMMA bone cement. Summary of background data. Viscosity is the characterizing parameter of PMMA bone cement, currently the standard augmentation material in PVP, and influences interdigitation and cement distribution inside the vertebral body, injected volume and extravasation, thereby affecting the clinical outcome of PVP. In PVP, low, medium and high viscosity PMMA bone cements are used interchangeably. However, effect of viscosity of cement on clinical outcome in patients with Osteoporotic Vertebral Compression Fractures (OVCFs) has not yet been explicit subject of investigation. Methods: Follow-up was conducted using a 0–10 Pain Intensity Numerical Rating Scale (PI-NRS) and the Short Form 36 (SF-36) Quality of Life (QoL) questionnaire before PVP and at 7 days (PI-NRS only), 1 month, 3 months and 12 months after PVP. Cement leakage was analyzed on direct post-operative CT-scanning. Injected cement volume was measured using a calibrated DICOM-viewer and the degree of interdigitation was assessed. At six and 52 weeks and at suspicion, patients were analyzed for the incidence of new fractures. Results: Thirty consecutive patients received PVP using low viscosity PMMA bone cement (OsteoPal-V. ®. ) for 62 OVCFs, followed by 34 patients who received PVP using medium viscosity PMMA bone cement (Disc-O-Tech. ®. ) for 67 OVCFs. Baseline characteristics were comparable between groups. Viscosity qualification was stated by the manufacturer. results regarding PI-NRS and SF-36 were comparable between both groups. Postoperative comparison of injected cement volume, degree of interdigitation, proportion of bipedicular procedures, incidence of new vertebral fractures and complications revealed no substantial differences between both groups. In the low viscosity group a significantly greater proportion of vertebrae showed cement extravastion (81,0% versus 71,6%, p = 0,029). Multiple logistic analysis revealed no definitive predictive factors for the occurrence of cement leakage (yes/ no) (Odds Ratio [95% CI], P):. Severity (acc to Genant et al): 1.82 [0,69 – 4.89], 0.229. Fracture Type (Genant et al): 1.22 [0.64 – 2.32], 0.550. Injected Volume: 0.98 [0.76 – 1.27], 0.875. Spinal Region: 0.87 [0.48 – 1.55], 0.628. Cement Viscosity: 0.42 [0.16 – 1.10], 0.076. Conclusion: No major differences in clinical outcome after PVP in OVCFs using low and medium viscosity PMMA bone cement were found. Viscosity of PMMA bone cement is likely to influence cement extravastion, although this could not be confirmed


The Journal of Bone & Joint Surgery British Volume
Vol. 92-B, Issue 7 | Pages 935 - 940
1 Jul 2010
McCalden RW Charron KD Yuan X Bourne RB Naudie DD MacDonald SJ

This was a safety study where the hypothesis was that the newer-design CPCS femoral stem would demonstrate similar early clinical results and micromovement to the well-established Exeter stem. Both are collarless, tapered, polished cemented stems, the only difference being a slight lateral to medial taper with the CPCS stem. A total of 34 patients were enrolled in a single-blinded randomised controlled trial in which 17 patients received a dedicated radiostereometric CPCS stem and 17 a radiostereometric Exeter stem. No difference was found in any of the outcome measures pre-operatively or post-operatively between groups. At two years, the mean subsidence for the CPCS stem was nearly half that seen for the Exeter stem (0.77 mm (−0.943 to 1.77) and 1.25 mm (0.719 to 1.625), respectively; p = 0.032). In contrast, the mean internal rotation of the CPCS stem was approximately twice that of the Exeter (1.61° (−1.07° to 4.33°) and 0.59° (0.97° to 1.64°), respectively; p = 0.048). Other migration patterns were not significantly different between the stems. The subtle differences in designs may explain the different patterns of migration.

Comparable migration with the Exeter stem suggests that the CPCS design will perform well in the long term.


Orthopaedic Proceedings
Vol. 92-B, Issue SUPP_I | Pages 238 - 238
1 Mar 2010
Pollintine P Harrison S Patel A Tilley D Miles A Gheduzzi S
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Introduction: Vertebroplasty is increasingly used in the treatment of painful osteoporotic vertebral fractures, and involves transpedicular injection of bone cement into the fractured vertebral body. Effective infiltration of the vertebral body cancellous bone by the cement is determined by the cement viscosity, and by the permeability of the bone. However, it is unclear how permeability is influenced by regional variations in porosity and architecture of bone within the vertebral body. The aim of the present study was to investigate how permeability is influenced by porosity and architecture of cancellous bone mimics. Methods: Cylindrical polyamide mimics of two types of cancellous bone structures were fabricated using selective laser sintering (SLS) techniques. Structure A had the rod-like vertical and horizontal trabeculae typical of the anterior vertebral body, while structure B had oblique trabeculae typical of the posterior-lateral vertebral body. Structure B had fewer trabeculae than A. Porosities of 80 and 90% were represented for both structures. Golden syrup, which has a viscosity similar to bone cement. 1. , was injected into the mimics at a constant speed using a ram driven by a materials testing machine. Pressure drop measurements across the mimic, made using a differential pressure transducer, were obtained at five different injection speeds. Permeability of each mimic was calculated from these measurements. 2. Two more repeat permeability measurements were performed on each mimic. Results: Repeat measurements were always within 12% of the mean value. For structure A the mean permeabilities were 1.26×10-7 and 1.82×10-7m2 for the 80 and the 90% porosity mimics respectively. The corresponding mean permeabilities for structure B were 1.92×10-7 and 2.86×10-7m2. Discussion: These preliminary results indicate that higher permeabilities occur in structures with higher porosities, and with structures containing fewer trabeculae that are arranged obliquely. Since permeability is a determinant of cement infiltration, taking into account patient-specific bone architecture parameters may improve the safety and clinical outcome of vertebroplasty. Future experiments will clarify in more detail the architectural parameters that have greatest effect on permeability


Orthopaedic Proceedings
Vol. 91-B, Issue SUPP_I | Pages 113 - 113
1 Mar 2009
Dall G Simpson P McKenzie S Breusch S
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Background: Several factors can alter a cements viscosity and hence it’s handling characteristics. An in vitro study was performed to ascertain whether anecdotal observations of differences in handling between batches of the same cement brand existed. Methods: 3 batches of Simplex P Tobramycin (SPT), Refobacin Bone Cement (RBC), SmartSet GHV (SSG) and Palacos R+G (PRG) were tested. 6 replicates of each batch were vacuum mixed and their viscosity in relation to time was measured in laboratory conditions (50 ±5% humidity and 23 ±1°C) using a rheometer. 6 replicates of each batch had their handling characteristics examined after they were hand mixed in theatre conditions. Results: Inter and intra-batch variability was seen in the viscosity of all brands of cements tested. Inter-batch calculations were influenced by high intra-batch viscosity variability. The viscosity of RBC cement was very similar to SSG, but significantly different to PRG (p = 0.01 at 5N and p = 0.009 at 40 N). Interpretation: Our results suggest that in clinical practice extrinsic factors such as preparation conditions and methods probably play a more important role than the cements intrinsic variability. However, variability in handling and viscosity will exist in all brands of cement prepared in theatre conditions and the surgeon needs to be aware why they may act differently


Orthopaedic Proceedings
Vol. 90-B, Issue SUPP_II | Pages 378 - 378
1 Jul 2008
Budnar V Bannister G
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Background: Inadequate proximal femoral pressures obtained during a cemented, primary hip replacement may lead to poor stem fixation. Proximal occlusion during stem insertion,may help in achieving a uniform and sustained rise in intra-medullary pressures, distally and proximally. High intra-medullary pressures correlate with better cement penetration and increased cement-bone interface push-out strength. Methodology: An In-vitro analysis of femoral pressures was performed. A femoral medullary cavity was created in plaster of Paris constrained in an aluminium cylinder. Intramedullary pressures were measured via pressure transducers. High viscosity bone cement (Palacos-R) was gunned into the medullary cavity. No.3 Exeter stem was inserted with no proximal occlusion, with thumb occlusion over the calcar and with the Exeter Horse-collar. Experiments were repeated by delaying the timing of insertion and with lower viscosity cement (Simplex-P). A small series of experiments were done to ensure that that the stem insertion was performed at standard cement viscosity. The experiments were carried out with the same viscosity of Palacos-R at 4 minutes and Simplex-P at 6 minutes. Palacos-R at 4 minutes 30 seconds had a higher viscosity. Results: A total of 54 experiments were performed. Of these 18 experiments were done with Palacos R cement, with the stem inserted early on in the curing phase and 18 with a delayed time of insertion. The last 18 experiments were performed with Simplex P cement with the stem inserted early on in its curing phase. Intramedullary pressures were better in all zones, for all cement modes, with proximal occlusion. The highest pressures were seen with Palacos-R at 4 minutes 30 seconds with proximal thumb occlusion. Stem insertion into Palacos-R at 4 minutes or 4 minutes 30 seconds, gave higher pressures than Simplex-P, with or without any form of occlusion. With Simplex-P, intramedullary pressures were higher, with Collar rather than thumb occlusion. Conclusion: Occluding the medial cal car area during stem insertion, is an effective way of achieving and sustaining high-pressures in the proximal and distal femur. The highest pressures are obtained with stem inserted into Palacos-R at 4 minutes 30 seconds, with proximal thumb occlusion. Collar occlusion may be better in achieving higher pressures, with lower viscosity, Simplex-P


Orthopaedic Proceedings
Vol. 90-B, Issue SUPP_I | Pages 174 - 174
1 Mar 2008
Mai DS
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There exists a lot literature referring to the cementing technique of hip replacements, but when talking about longevity of knee prostheses only seldom the cementing technique is mentioned even though 90% of the knees are cemented. Especially the tibial component, that has to cope with different forces such as pressure, rotation, tilt and sliding, is said to last longer when cemented. Cementing Technique: There are many aspects that need to be thought of when cementing knee prostheses:. The preparation of the bone: The preparation of the surface of the bone is of great importance, as the-bond of the cement with the bone is by the shape of the surfaces and not by a chemical reaction. A good penetration of the cement into the cancellous-bone enlarges the connecting surface and optimizes the power transmission. The pulse-lavage is the most effective to open the spongy bone. Sclerotic bone needs to be penetrated. Selection of cement: PMMA-cement (Polymeth-ylmetacrylat) is used with proven effectiveness since 1958 (Charnley). Very Similar to the well known cement Palacos (BiometMerck) is the new SmartSet GHV (DePuy) but it provides a longer time for processing, which is useful when cementing all components in one go. Mixing and hardening time are therefore shorter. Mixing of the cement: Mixing is mostly done manually even though it is known that the quality of the cement is minor than with a vacuum system. The advances of such a system are better microporosity, no air bubbles, and safety for the staff, who breathe less fumes. Application of cementviscosity: The cement can be applied to the prosthesis or directly onto the bone. If the implant is precoated, the viscosity of the cement should be low to achieve better joint. The bone should in any case be dry to avoid mixing with blood. Pressure: During implantation a short high pressure is of importance for the depth of penetration. Some implants have an edge to guarantee better distribution of the pressure. During the hardening of the cement the pressure has to b ekept at a certain level as the volume of the cement changes a bit during the polimerisation. Hardening: The pressure needs to be controlled avoiding small movements. When cementing all components at once the ligaments have to be balanced, otherwise unnoticed deviations might occur. The leg should not be hyperextended to avoid tilting of the components. Temperature of polimerisation: The temperature can be reduced in vivo by cooling of the bone or the cement and by good spongy bone that transports the temperature away. If the cement penetrates more than 5 mm or its homogeneous thickness is more than 3mm osteonecrosis is likely to occur. Thickness of cement layer: Several authors and the finite element measurements found out, that acement layer from 2–5 mm ensures good stability for the tibial component. Cementing the shaft does not lead to significant better results but may lead to atrophy of the bone underneath the tibial plateau. Femoral components show good results also uncemented. Excess of cement: Cement that juts out must be removed especially in the dorsal parts, where an impingement can be produced. Bits in the soft tissue must also be removed with care. Cement should not touch the polyethylene during the whole procedure. Antibiotics: The quality and longevity of the cement is reduced by adding antibiotics because of resulting higher porosity. A special management for risk patientsis necessary. When cementing knee prostheses one should give high attention to the cementing technique as especially a good anchorage of the tibial component will lead to longevity of the implant


The Journal of Bone & Joint Surgery British Volume
Vol. 90-B, Issue 1 | Pages 107 - 113
1 Jan 2008
Scheerlinck T Vandenbussche P Noble PC

Interfacial defects between the cement mantle and a hip implant may arise from constrained shrinkage of the cement or from air introduced during insertion of the stem. Shrinkage-induced interfacial porosity consists of small pores randomly located around the stem, whereas introduced interfacial gaps are large, individual and less uniformly distributed areas of stem-cement separation. Using a validated CT-based technique, we investigated the extent, morphology and distribution of interfacial gaps for two types of stem, the Charnley-Kerboul and the Lubinus SPII, and for two techniques of implantation, line-to-line and undersized.

The interfacial gaps were variable and involved a mean of 6.43% (sd 8.99) of the surface of the stem. Neither the type of implant nor the technique of implantation had a significant effect on the regions of the gaps, which occurred more often over the flat areas of the implant than along the corners of the stems, and were more common proximally than distally for Charnley-Kerboul stems cemented line-to-line. Interfacial defects could have a major effect on the stability and survival of the implant.


The Journal of Bone & Joint Surgery British Volume
Vol. 89-B, Issue 8 | Pages 1115 - 1121
1 Aug 2007
Messick KJ Miller MA Damron LA Race A Clarke MT Mann KA

The role of vacuum mixing on the reduction of porosity and on the clinical performance of cemented total hip replacements remains uncertain. We have used paired femoral constructs prepared with either hand-mixed or vacuum-mixed cement in a cadaver model which simulated intra-operative conditions during cementing of the femoral component. After the cement had cured, the distribution of its porosity was determined, as was the strength of the cement-stem and cement-bone interfaces.

The overall fraction of the pore area was similar for both hand-mixed and vacuum-mixed cement (hand 6%; vacuum 5.7%; paired t-test, p = 0.187). The linear pore fractions at the interfaces were also similar for the two techniques. The pore number-density was much higher for the hand-mixed cement (paired t-test, p = 0.0013). The strength of the cement-stem interface was greater with the hand-mixed cement (paired t-test, p = 0.0005), while the strength of the cement-bone interface was not affected by the conditions of mixing (paired t-test, p = 0.275). The reduction in porosity with vacuum mixing did not affect the porosity of the mantle, but the distribution of the porosity can be affected by the technique of mixing used.


The Journal of Bone & Joint Surgery British Volume
Vol. 88-B, Issue 11 | Pages 1409 - 1418
1 Nov 2006
Scheerlinck T Casteleyn P

We undertook a review of the literature relating to the two basic stem designs in use in cemented hip replacement, namely loaded tapers or force-closed femoral stems, and the composite beam or shape-closed designs. The associated stem fixation theory as understood from in vitro studies and finite element modelling were examined with reference to the survivorship results for each of the concepts of fixation.

It is clear that both design principles are capable of producing successful long-term results, providing that their specific requirements of stem metallurgy, shape and surface finish, preparation of the bone and handling of the cement are observed.