Foam Block Research Articles

Experimental and numerical investigation on incremental sheet forming with flexible die-support from metallic foam

Poor geometric accuracy of workpieces plagues single-point incremental forming (SPIF) due to lack of support and unwanted plastic deformation. In this work, metallic foam blocks are used as flexible die-support in duplex (or two-point) incremental forming (DPIF), and the geometric accuracy of workpieces is significantly improved by comparing to single point incremental forming as well as other improved strategies as demonstrated through both finite element simulation and experiments. Since the metallic foam is plastically deformable and easy to machine (or cut) and has a certain strength, DPIF with flexible die-support (DPIF-F) improves geometric accuracy but also maintains the flexibility of incremental sheet forming.

Partially threaded headless screw may benefit adequate interfragmentary compression and reduced driving torque for small bone fixation.

Headless compression screws (HCSs) are commonly used to fixate small bones and articular fractures. Understanding the biomechanical efficacy of different HCS designs can help surgeons make proper interfragmentary compression when a specific implant is chosen. HCSs with three different central shaft designs (unthreaded, fully threaded, and partially threaded) were studied: the Herbert-Whipple, Mini-Acutrak 2, and headless reduction (HLR). Polyurethane foam blocks were machined with a simulated fracture gap of 0.5 mm and set onto a custom-made jig to simultaneously measure compression force and driving torque during screw insertion. The maximal achievable compression forces and driving torques recorded were 47.4 ± 0.9 N and 145.11 ± 1.65 N mm for the HLR, 50.98 ± 1.29 N and 152.62 ± 2.83 N mm for the Mini-Acutrak 2, and 19.33 ± 1.0 N and 33.4 ± 2.2 N mm for the Herbert-Whipple. Overall, the compression force of the Mini-Acutrak 2 and HLR increased with the torque. Unlike the other screws, the Herbert-Whipple's driving torque increased while the compression force decreased after peak compression force was achieved. The partially threaded shaft design (HLR) demonstrated equivalent biomechanical advantage with the Mini-Acutrak 2 in interfragmentary compression. The HCSs with cone-shaped proximal ends (HLR and Mini-Acutrak 2) maintained their compression force during over-fastening, whereas the unthreaded central shaft of the Herbert-Whipple screw caused it to lose compression force.

Numerical Study of Heat Transfer Enhancement for a Flat Plate Solar Collector by Adding Metal Foam Blocks

Numerical study has been conducted to investigate the thermal performance enhancement of flat plate solar water collector by integrating the solar collector with metal foam blocks.The flow is assumed to be steady, incompressible and two dimensional in an inclined channel. The channel is provided with eight foam blocks manufactured form copper. The Brinkman-Forchheimer extended Darcy model is utilized to simulate the flow in the porous medium and the Navier-Stokes equation in the fluid region. The energy equation is used with local thermal equilibrium (LTE) assumption to simulate the thermofield inside the porous medium. The current investigation covers a range of solar radiation intensity at 09:00 AM, 12:00 PM, and 04:00 PM on the 8th of July 2016 under Iraq climate conditions, and a range of Reynolds number of (207<Re<625). The results show that the insertion of metal foam blocks caused a reduction in the absorber plate temperature and the possible enhancement in the heat transfer coefficient is more than 80% and as a result, the collector exhaust temperature will increase.

Enhancement of heat exchanger thermal hydraulic performance using aluminum foam

This paper deals with an experimental study of a turbulent forced convection in a rectangular channel partly fitted with aluminum metallic foam blocks. Experiments were carried out on samples having a constant porosity of 93.8%, different grades of 5, 20 and 40 PPI, and three different height ratios of 0.6, 0.8 and 1. The blocks were arranged in a baffle like configuration. A constant heat flux of 2 W/cm2 was applied on the bottom wall of the test section, while air velocity was varied from 1 to 5 m·s−1. Temperatures of the wall along the flow direction as well as those of the inlet and outlet sections have been measured. Additionally, pressure drop measurements across the aluminum foam samples were performed. The results showed that there is an optimal choice of the height and the grade of the metal foam for which the heat transfer and pressure drop (for an optimal design of heat exchangers) to reach the design goal. Moreover, this configuration was compared to solid fins aluminum baffles widely used in heat exchangers.

Production of Aerated Foamed Concrete with Industrial Waste from the Gems and Jewels Sector of Rio Grande do Sul-Brazil

The use of solid waste for the development of new building materials has been an alternative to reduce environmental impacts through the preservation of natural resources. In this context, this paper evaluates the possibility of using agate gemstone waste, called rolled powder, which basically consists of silica (SiO2), in the manufacture of aerated foamed concrete blocks completely replacing the natural sand. Preformed foam was used as the air entrained by mechanical stirring with a mixture of natural foaming agents derived from coconut. To produce test specimens, the water/cement ratio and foam concentrations were varied, with three and four levels, respectively. The specimens were left for 28 days at room temperature to be cured, and then underwent analysis to determine their compressive strength, density, and the distribution of air-voids. The experiments demonstrated that the best water/cement ratio was 1.28 for 18% (of total solid mass) addition of foam, which generated a sample with a density of 430 kg/m3, and a compressive strength of 1.07 MPa. The result for compressive strength is 11% smaller than the requirements of the Brazilian standard (NBR 13438) for autoclaved aerated concrete blocks, but the results are promising.

Biomechanical Comparison of Inter-fragmentary Compression Pressures: Lag Screw versus Herbert Screw for Anterior Odontoid Screw Fixation.

ObjectiveThe purpose of the present study was to compare inter-fragmentary compression pressures after fixation of a simulated type II odontoid fracture with the headless compression Herbert screw and a half threaded cannulated lag screw.MethodsWe compared inter-fragmentary compression pressures between 40- and 45-mm long 4.5-mm Herbert screws (n=8 and n=9, respectively) and 40- and 45-mm long 4.0-mm cannulated lag screws (n=7 and n=10, respectively) after insertion into rigid polyurethane foam test blocks (Sawbones, Vashon, WA, USA). A washer load cell was placed between the two segments of test blocks to measure the compression force. Because the total length of each foam block was 42 mm, the 40-mm screws were embedded in the cancellous foam, while the 45-mm screws penetrated the denser cortical foam at the bottom. This enabled us to compare inter-fragmentary compression pressures as they are affected by the penetration of the apical dens tip by the screws.ResultsThe mean compression pressures of the 40- and 45-mm long cannulated lag screws were 50.48±1.20 N and 53.88±1.02 N, respectively, which was not statistically significant (p=0.0551). The mean compression pressures of the 40-mm long Herbert screw was 52.82±2.17 N, and was not statistically significant compared with the 40-mm long cannulated lag screw (p=0.3679). However, 45-mm Herbert screw had significantly higher mean compression pressure (60.68±2.03 N) than both the 45-mm cannulated lag screw and the 40-mm Herbert screw (p=0.0049 and p=0.0246, respectively).ConclusionOur results showed that inter-fragmentary compression pressures of the Herbert screw were significantly increased when the screw tip penetrated the opposite dens cortical foam. This can support the generally recommended surgical technique that, in order to facilitate maximal reduction of the fracture gap using anterior odontoid screws, it is essential to penetrate the apical dens tip with the screw.

An experimental setup for observation of smoldering‐to‐flaming transition on flexible foam/fabric assemblies

SummaryFires that involve upholstered furniture frequently begin as a smoldering combustion and, with time, transition to a flaming combustion, which sharply increases the level of hazard. Therefore, understanding how the compositions of the primary flammable components of the furniture, ie, flexible foam and upholstery fabric, affect this transition is important for fire safety considerations. In the current study, an experiment was designed to observe this transition using a sample consisting of 30 × 15 × 6 cm3 rectangular foam block covered with 30 × 15 cm2 piece of fabric. For a representative system of 1.8 lb/ft3 (29 kg/m3) flexible polyurethane foam and 11 oz (0.37 kg/m2) cotton fabric, 0.69 transition probability was measured. This probability decreased by a factor of 4 when a small amount of phosphorus‐based flame retardant, Fyrol® HF‐9, was added to the foam. The transition to flaming was speculated to be associated with the formation of adjacent pyrolysis and smoldering regions within the foam. The pyrolysis region, dominated by anaerobic decomposition, provided gaseous fuel, the ignition of which resulted in the transition. The smoldering region, dominated by oxidation reactions at the solid‐gas interface, generated the heat necessary to maintain the pyrolysis process and ignite the gaseous fuel.

A stepwise under-prepared osteotomy technique improves primary stability in shallow-placed implants: a preliminary study for simultaneous vertical ridge augmentation.

Simultaneous vertical ridge augmentation (VRA) can reduce treatment procedures and surgery time, but the concomitant reduction in primary stability (PS) of a shallow-placed implant imparts risk to its prognosis. Although several studies have reported improvements in PS, there is little information from any simultaneous VRA model. This study aimed to evaluate whether tapered implants with stepwise under-prepared osteotomy could improve the PS of shallow-placed implants in an in vitro model of simultaneous VRA. Tapered implants (Straumann® Bone Level Tapered implant; BLT) and hybrid implants (Straumann® Bone Level implant; BL) were investigated in this study. A total of 80 osteotomies of different depths (4, 6, 8, 10mm) were created in rigid polyurethane foam blocks, and each BLT and BL was inserted by either standard (BLT-S, BL-S) or a stepwise under-prepared (BLT-U, BL-U) osteotomy protocol. The PS was evaluated by measuring maximum insertion torque (IT), implant stability quotient (ISQ), and removal torque (RT). The significance level was set at P<0.05. There were no significant differences in IT, ISQ or RT when comparing BLT-S and BL-S or BLT-U and BL-U at placement depths of 6 and 8mm. When comparison was made between osteotomy protocols, IT was significantly greater in BLT-U than in BLT-S at all placement depths. A stepwise under-prepared osteotomy protocol improves initial stability of a tapered implant even in a shallow-placed implant model. BLT-U could be a useful protocol for simultaneous VRA.

Underwater blast resistance of sacrificial claddings with small/significant strain hardening

The vitality and fighting capacity of warships will be influenced by the underwater explosion–induced shock loadings. The foam materials have excellent energy dissipation capabilities and are widely used in mitigating impact/shock. In this article, a one-dimensional model for the shock mitigation of cellular claddings exhibiting small/significant strain hardening is proposed for both water blast loading and hydrostatic pressure. Special emphases are concentrated on the cellular material compression with actual stress–strain relationship and the effects of hydrostatic pressure on the shock mitigation performance of the cladding. Finite element models are developed to verify the analytical model. When considering the actual material relationship of the cellular claddings, the compaction mechanism is complex due to multiple reflections. A reflected secondary compression wave generates and propagates from the clamped end to the impinged end for a foam block with finite thickness. Later, there are even third or more compaction waves. It is worth to note that the part inside the secondary compacted zone continue to deform in quasi-static “Homogeneous” mode. Moreover, the effects of the hydrostatic pressure on the foam compression are revealed. The results can guide the design of such cellular claddings to water blast for naval ships.

Natural convection in metal foam heat sinks with open slots

Natural convection in metal foam heat sinks with open slots was investigated experimentally. The test sample was made in-house by attaching several foam strips having fixed width of 10mm and length of 100mm onto a substrate of 100×100×4mm3 in size. A total of 29 test samples with different slot widths (s=0/2.86/5/8/12.5/20mm) and foam heights (H=10/20/40/60/80mm) were tested under both horizontal and vertical orientations for each sample. The zero width of open slots corresponds to a heat sink with a single foam block as considered in open literature, while the non-zero open slot width 2.86/5/8/12.5/20mm corresponds to 8/7/6/5/4 foam strips in a heat sink, respectively. Compared to a single foam block, the foam with open slots are more permeable for air penetrating through the heat sink. More foam strips means more heat transfer area available but less permeation of the heat sink. Experimental results revealed that there exists an optimum open slot width (5–8mm) for maximum heat transfer coefficient at given heat sink volume. With optimum open slot width, the heat transfer coefficient is enhanced by 14.9%, 21.3%, 37.6%, and 38.2% relative to single foam block (s=0mm) at the foam height of 10mm, 20mm, 40mm, and 80mm, respectively.

Gait symmetry in walking and running after unilateral total knee replacement: Is there a relationship between walking and running symmetry?

The purpose of this study was to quantify the initial stability of a highly porous titanium cup using an acetabular bone defect model.The maximum torque of a highly porous titanium cup, with a pore size of 640 μm and porosity of 60%, was measured using rotational and lever-out torque testing and compared to that of a titanium-sprayed cup. The bone models were prepared using a polyurethane foam block and had three levels of bone coverage: 100, 70, and 50%.The highly porous titanium cup demonstrated significantly higher maximum torque than the titanium-sprayed cups in the three levels of bone defects. On rotational torque testing, it was found to be 1.5, 1.3, and 1.3 times stronger than the titanium-sprayed cups with 100, 70 and 50% bone coverage, respectively. Furthermore, it was found to be 2.2, 2.3, and 1.5 times stronger on lever-out testing than the titanium-sprayed cup. No breakage in the porous layers was noted during the testing.This study provides additional evidence of the initial stability of highly porous titanium cup, even in the presence of acetabular bone defects.

The insertion torque-depth curve integral as a measure of implant primary stability: An in vitro study on polyurethane foam blocks

Statement of problemRecent research has shown that dynamic parameters correlate with insertion energy—that is, the total work needed to place an implant into its site—might convey more reliable information concerning immediate implant primary stability at insertion than the commonly used insertion torque (IT), the reverse torque (RT), or the implant stability quotient (ISQ). Yet knowledge on these dynamic parameters is still limited. PurposeThe purpose of this in vitro study was to evaluate whether an energy-related parameter, the torque-depth curve integral (I), could be a reliable measure of primary stability. This was done by assessing if (I) measurement was operator-independent, by investigating its correlation with other known primary stability parameters (IT, RT, or ISQ) by quantifying the (I) average error and correlating (I), IT, RT, and ISQ variations with bone density. Material and methodsFive operators placed 200 implants in polyurethane foam blocks of different densities using a micromotor that calculated the (I) during implant placement. Primary implant stability was assessed by measuring the ISQ, IT, and RT. ANOVA tests were used to evaluate whether measurements were operator independent (P>.05 in all cases). A correlation analysis was performed between (I) and IT, ISQ, and RT. The (I) average error was calculated and compared with that of the other parameters by ANOVA. (I)-density, IT-density, ISQ-density, and RT-density plots were drawn, and their slopes were compared by ANCOVA. ResultsThe (I) measurements were operator independent and correlated with IT, ISQ, and RT. The average error of these parameters was not significantly different (P>.05 in all cases). The (I)-density, IT-density, ISQ-density, and RT-density curves were linear in the 0.16 to 0.49 g/cm³ range, with the (I)-density curves having a significantly greater slope than those regarding the other parameters (P≤.001 in all cases). ConclusionsThe torque-depth curve integral (I) provides a reliable assessment of primary stability and shows a greater sensitivity to density variations than other known primary stability parameters.

Effect of Metal Foam Insertion on Thermal Performance of Flat-Plate Water Solar Collector Under Iraqi Climate Conditions

An experimental study is conducted under Iraqi climate conditions to investigate the effect of adding metal foam blocks into solar water collector risers. Two flat-plate solar water collectors are tested in Baghdad city (latitude $$33.3{^{\circ }}\hbox {N}$$ ) in July, August, September, and October 2016. Copper foam blocks are inserted inside the risers of the first solar collector, while the risers of the second solar collector are kept opened. Results demonstrated that the insertion of copper foam blocks caused a reduction in the mean absorber plate temperature by 8.2 $${^{\circ }}\hbox {C}$$ , and as a consequence, the convection heat transfer coefficient values are almost doubled. The daily collector thermal efficiency and the output thermal power are also increased. The presence of copper foam blocks in the solar collector risers is found to be more effective for higher solar radiation intensity, namely at the end of July and the beginning of August. The insertion of copper foam blocks also caused a remarkable jump in the water pressure drop across the collector to about 153% and as a result; the benefit factor was lower than unity for all test cases.

Basics of Optimization Algorithm for Insulating Porous Materials Structure

Сегодня в связи с ужесточением требований по теплозащите зданий и сооружений заметно возрос спрос на качественные теплоизоляционные пористые материалы, задачи создания которых связаны с неопределенностями в различных областях. Это, в первую очередь, неопределенность условий реального функционирования будущих конструкций и неопределенность совокупности задач, которые оцениваются критериями эффективности. В статье обоснована необходимость построения математических моделей зависимостей различных параметров материалов и предлагается метод построения критерия теплопроводности пористого материала на примере пенобетона неавтоклавного твердения. Теплопроводность пористых материалов напрямую зависит от характера пористости и определяется плотностью. В соответствии с этим утверждением проведен анализ теплопереноса в пенобетонном блоке. Перенос тепла рассмотрен через пеноблок в целом, отдельно рассмотрены свойства его составляющих, которые формируют общий теплопоток: цементной матрицы и пор, заполненных воздухом. Использованы функциональные зависимости параметров теплопотока от влажности, пористости, размера и количества пор, содержания в них воды, структуры цементной матрицы. Выведена формула для определения значения коэффициента теплопроводности пенобетона. Формализована задача с поиском критериев оптимальности для пенобетонных конструкций, которая решается методом многокритериальной оптимизации.

Experimentally validated analytical expressions for the thermal efficiencies and thermal resistances of porous metal foam-fins

Novel, analytical expressions are developed for the thermal efficiency and thermal resistance associated with forced convection and conduction within a cylindrically shaped, open porous medium that is attached concentrically to a circular tube. Using the new analytical expression in conjunction with a two-temperature porous medium numerical model, a companion semi-analytical expression for the thermal efficiency of a cubical foam block attached on-center to a circular tube is also developed. Heat rates predicted with the semi-analytical model are verified through comparison with experimentally measured heat transfer rates using open-cell metal foam. Foam thermal resistances are also quantified over a range of operating conditions. The recommended ranges of application of the analytical and experimentally verified semi-analytical expressions for the thermal efficiency of both annular and square-shaped foams are also presented.

Effect of interfragmentary gap on compression force in a headless compression screw used for scaphoid fixation.

We investigated the effect of an interfragmentary gap on the final compression force using the Acutrak 2 Mini headless compression screw (length 26 mm) (Acumed, Hillsboro, OR, USA). Two blocks of solid rigid polyurethane foam in a custom jig were separated by spacers of varying thickness (1.0, 1.5, 2.0 and 2.5 mm) to simulate an interfragmentary gap. The spacers were removed before full insertion of the screw and the compression force was measured when the screw was buried 2 mm below the surface of the upper block. Gaps of 1.5 mm and 2.0 mm resulted in significantly decreased compression forces, whereas there was no significant decrease in compression force with a gap of 1 mm. An interfragmentary gap of 2.5 mm did not result in any contact between blocks. We conclude that an increased interfragmentary gap leads to decreased compression force with this screw, which may have implications on fracture healing.

A fully synthetic lung model for wound-ballistic experiments—First results

PurposeToday, synthetic models have all but replaced animal and corpse models in examining damage to soft-tissues and skeletal structures by ballistic trauma. As, however, non-solid organs such as the lungs, have not been able to be replaced by a fully synthetic model we attempted to create such a model. Material and methods20% ordnance gelatine was frothed with a household mixer and cooled to stable foam. Several of these foam blocks were then stuck together with liquid gelatine and placed between 10% gelatine blocks. As controls, we embedded pig lungs in gelatine and compared the wound channels seen in computed tomography created upon shooting with 9mm Luger. ResultsThe fully synthetic models displayed radiological and physical densities comparable to real lungs. The wound profile characteristics of the fully synthetic lung models were very similar to the semisynthetic swine-gelatine models regarding the permanent wound cavity. Furthermore, in both semi- and fully synthetic models we detected a ring surrounding the permanent wound channel, most likely representing the remnants of the temporary wound cavity. ConclusionOur results indicate that this fully synthetic lung model is a viable substitute for ballistic experiments on lungs. We believe that further research on the temporary wound channel in lungs is possible with this model in order to provide more insight into the effect of ballistic trauma to the lungs not seen otherwise.

Trace DNA evidence dynamics: An investigation into the deposition and persistence of directly- and indirectly-transferred DNA on regularly-used knives

Empirical data on the transfer and persistence of trace DNA are crucial to the evaluation of forensic DNA evidence. This evaluation can be complicated by the occurrence of indirect DNA transfer; the possibility of which is well established, but research into such transfer is often focussed on unrealistic situations, e.g. handling of DNA-free items after participants have shaken hands for 1–2min. To simulate more realistic scenarios, this study investigated the deposition and persistence of both directly- and indirectly-transferred DNA on knives that had been artificially set up as ‘regularly-used’. Each knife was handled in a prescribed manner by a specific participant over two consecutive days to simulate regular use. Each participant then shook hands for 10s with a fellow volunteer and immediately stabbed one of their knives into a foam block repeatedly for 60s. DNA was recovered by mini-taping from triplicate sets of knife handles from four pairings of volunteers after regular use, and at one hour, one day and one week after the handshaking and stabbing events.Total amounts of DNA recovered from the knives, regularly used by a single person, varied among individuals; one volunteer consistently deposited significantly greater amounts than the others, whilst another volunteer did not always leave complete profiles. DNA attributed to the regular user persisted for at least a week, declining with increasing time between DNA deposition and recovery. Non-donor DNA was co-deposited at <5% of the profiles recovered, except for one volunteer, who consistently left DNA from their romantic partner on their knives at ∼25% and ∼11% of the profiles before and after the handshaking and stabbing events, respectively. In three pairings of volunteers, after the handshaking and stabbing events, alleles that could be attributed to the respective handshakers’ profiles were detected as partial minor profiles, equating to ∼10% of the profiles recovered. For the fourth pairing of volunteers, only complete single-source DNA profiles matching the regular user’s profile were recovered. However, it is important to note that, when indirectly-transferred handshaker DNA was detected, it declined with increasing time between DNA deposition and recovery.These data provide an initial insight into the detection and persistence of directly- and indirectly-transferred DNA that extend the data already available on forensic DNA transfer. The results herein suggest that the sooner an item is sampled after an offence has occurred, the greater the chance of recovering indirectly-transferred DNA, which has implications for forensic reconstructions.

The Effect of Cervical Interbody Cage Morphology, Material Composition, and Substrate Density on Cage Subsidence.

Interbody cages used in spinal fusion surgery can subside into the adjacent vertebral bodies after implantation, leading to loss of spinal height, malalignment, and possible radicular symptoms. Several factors may contribute to cage subsidence. This in vitro investigation examined the possible contribution of substrate density, cage contact area (ie, cage footprint), cage filling, cage end plate surface texture, and cage material composition on the magnitude of subsidence. Commercially available cervical interbody cages of two sizes (16 × 12 mm and 17 × 14 mm) were implanted between foam blocks of two different densities and were cyclically loaded. Cages were made of titanium alloy (Ti4Al6V), silicon nitride ceramic (Si3N4), or polyether ether ketone (n = 8 cages of each material type). Additional testing was performed on Si3N4 cages of the smaller size with nontextured surfaces and with filled cores. Subsidence measurements showed that lower foam density had the greatest influence on subsidence, followed by smaller cage footprint. Cage material had no effect on subsidence. In the additional testing of small-footprint Si3N4 cages, the cages in which the core was filled with a load-bearing porous material had less subsidence in lower-density foam than the cages with an empty core had, whereas cage end plate surface texture had no effect on subsidence. Ranking of the relative impact of these factors indicated that substrate density had the greatest contribution to the measured subsidence (approximately 1.7 times and approximately 67 times greater than the contributions of cage footprint area and material, respectively). The contribution of cage footprint area to subsidence was found to be 40 times greater than the contribution of cage material to subsidence.

Anterior Lumbar Interbody Fusion Integrated Screw Cages: Intrinsic Load Generation, Subsidence, and Torsional Stability.

To perform a repeatable idealized in vitro model to evaluate the effects of key design features and integrated screw fixation on unloaded surface engagement, subsidence, and torsional stability. We evaluated four different stand-alone anterior lumbar interbody fusion (ALIF) cages with two, three, and four screw designs. Polyurethane (saw-bone) foam blocks were used to simulate the vertebral bone. Fuji Film was used to measure the contact footprint, average pressure, and load generated by fixating the cages with screws. Subsidence was tested by axially loading the constructs at 10 N/s to 400 N and torsional load was applied +/-1 Nm for 10 cycles to assess stability. Outcome measures included total subsidence and maximal torsional angle range. Cages 1, 2, and 4 were symmetrical and produced similar results in terms of contact footprint, average pressure, and load. The addition of integrated screws into the cage-bone block construct demonstrated a clear trend towards decreased subsidence. Cage 2 with surface titanium angled ridges and a keel produced the greatest subsidence with and without screws, significantly more than all other cages ( P < 0.05). Angular rotation was not significantly affected by the addition of screws ( P < 0.066). A statistically significant correlation existed between subsidence and reduced angular rotation across all cage constructs ( P = 0.018). Each stand-alone cage featured unique surface characteristics, which resulted in differing cage-foam interface engagement, influencing the subsidence and torsional angle. Increased subsidence significantly reduced the torsional angle across all cage constructs.