Relative Axial Movement Research Articles

A decreased ratio of height of lateral femoral condyle to anteroposterior diameter is a risk factor for anterior cruciate ligament rupture

BackgroundStudies have shown that the spherical shape of the lateral femoral condyle has a clear relationship with the relative axial movement of tibiofemoral joint and the anterior cruciate ligament (ACL) rupture. The purpose of this study was to describe the distal curvature of the lateral femoral condyle by ratio of height of lateral femoral condyle to anteroposterior diameter (HAPR), and evaluate its correlation with ACL rupture.MethodsA retrospective case-control study of 64 patients was conducted. Two age-and sex-matched cohorts (each n = 32) were analyzed: primary ACL ruptures, and a control group consisting of isolated meniscal tears. On the radiograph, the distance from the intersection of the axis of the distal femur and the anteriorly diameter of the lateral femoral condyle to the lower point of the lateral femoral condyle divided by the anteriorly diameter of the lateral femoral condyle is HAPR. The HAPR was measured by digital radiograph imaging systems (DR) to quantify femoral sphericity. Cutoff values were defined; and diagnostic performance of the risk factors was assessed. Meanwhile, we measured the posterior tibial slope (PTS) on radiograph and compared the two methods to evaluate the significance of HAPR in predicting ACL rupture.ResultsA total of sixty-four patients who met the inclusion criteria were included in the final analysis (32 with primary ACL rupture, 32 controls). The HAPR was smaller in the knees with primary ACL rupture (0.31 ± 0.02) than that of the control group (0.33 ± 0.02) (p < 0.01). The PTS was bigger in the knees with primary ACL rupture (8.18 ± 2.77) than that of the control group (6.61 ± 2.85) (p = 0.036). The AUC of HAPR was bigger (0.825; 95% CI, 0.72–0.93) than that of PTS (0.675; 95%CI, 0.85–0.81). The calculated cutoff of HAPR of 0.32 (Youden index, 0.56) was associated with an increased risk for ACL rupture, with sensitivity of 75% and specificity of 81% to predict an ACL rupture.ConclusionsThis study showed that a decreased HAPR is associated with an ACL rupture, and the decrease of HAPR was more significant in predicting ACL ruptures than the PTS. This helps clinicians identify susceptible individuals who may benefit from targeted ACL rupture prevention counseling and intervention.

The effect of punch tip geometry on powder movement during the tableting process.

Axial and radial powder movements during the tableting process have been studied using punches with various tip geometries. Radial powder movement has been shown to occur. Alteration of punch tip geometry did affect both axial and radial powder movement, the extent being dependent on the relative curvature of the punch tip. Addition of lubricant decreased relative axial movement but had little effect on radial movement.

Finite Element Analysis of the Effects of Pedicle Screw Fixation Nut Loosening on Lumbar Interbody Fusion Based on the Elasto-Plateau Plasticity of Bone Characteristics

Cylindrical cages and pedicle screw fixation (PSF) have been used for the setting of a lumbar interbody fusion. To investigate the effects of PSF-nut loosening on lumbar interbody fusion based on the elasto-plateau plasticity of bone characteristics. The stress-strain curves of bone materials beneath the cages show linear elastic behavior before yielding and then seem to be plateau plastic deformation with further compression strain until opposing cell walls contact. Cancellous bone was assumed to be linearly elastic followed by nonlinearly plastic such as crushable foam behavior. The deformation and failure processes caused by loosening of PSF-nuts, in particular, are addressed by means of finite element analysis. Two finite element models, including anterior (or posterior) lumbar interbody fusion for the human lumbar L4-L5 segments, were constructed. In the respective models, 2 types of PSF were considered such as a solid PSF without relative movement between rod and screw, and a tightened PSF with relative axial movement of the rod between them due to the slight loosening of 2 nuts of L4. The slight loosening of nuts showed much greater levels of bone strain with relative motion at the bone-implant interface compared with the PSF with firmly tightened nuts. The loosening 2 of the 4 nuts imposed an excessive burden on the remaining screws. By the consideration of the elasto-plateau plastic behavior of cancellous bone and the relative motion at the contact interface between screw and rod, much more exact behaviors of bone failure were predicted. Slight loosening of the nut would cause a possible risk of segmental instability. With difficulty in either tightening the nut firmly during actual operation or keeping the nut-locking mechanism functioning perfectly in the postoperative state, an enhanced design methodology with more effective locking mechanism is required. Slight PSF-nut loosening may increase risks of failure processes such as rod migration, rod breakage, screw breakage, screw loosening or cage loosening. Different mechanisms however, can be considered; rod breakage and screw breakages are related to the higher stress level of the rod and screw while rod migration is associated with slight nut-loosening. Especially, in the case of a nonsymmetric nut-loosening the risk would be increased. Thus, further study is necessary for improving the current design of PSFs.

A Case of Accidental Hypotension Caused by Drug Leakage through the Rubber Piston in a Prefilled Inovan Injection 0.3% Syringe

A Case of Accidental Hypotension Caused by Drug Leakage through the Rubber Piston in a Prefilled Inovan Injection 0.3% Syringe

Mobilization of soil loads on buried, polyethylene natural gas pipelines subject to relative axial displacements

The performance of buried, medium-density polyethylene (MDPE) pipes subject to movements relative to the soil in the direction of the pipe axis is investigated by full-scale physical model testing conducted using a large soil box. A new closed-form solution was developed to account for the nonlinear material response of MDPE pipes under axial loading, and the analytical results are compared with the results obtained from the full-scale pipe pullout testing. The closed-form solution provides a rational framework to estimate the response of the pipe (i.e., level of strain, force) and the mobilized frictional length along the pipe for a known relative axial pipe movement. The approach, in turn, could be used to estimate the relative axial movements needed for pipe failure, which is an important consideration in the evaluation of field-performance of pipe systems located in areas of potential ground movement. The methodology is an important initial step towards the development of representative axial soil-springs representing complex pipe–soil interaction encountered in relatively extensible, buried polyethylene (PE) pipe systems subject to soil loading arising from ground movements.

Self-orienting directionally sensitive geophone

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Vibration damper ring

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Month in the Patent Office

In an aircraft, which may be a guided missile, the wings 1 are folded about a common fore‐and‐aft axis 2 in the fuselage in order that the aircraft or missile may be housed within the bomb bay of a larger aircraft. Each wing carries spars 3 each pivoted to a frame member 6 of the fuselage by a hollow pivot comprising a sleeve 7 passing through apertures in member 6 and spar 3 to form a hinge with a coaxial bore. Through these bores there extends a control rod 8 for operating a control surface 9 pivoted at 11 to the trailing edge of the aerofoil 1. Control rod 8 is formed in two portions connected together at 14 by a joint which prevents relative axial movement but permits relative rotational movement when the wings and control surfaces are folded about axis 2. Pins 5 are provided to co‐operate with slots 4 in spars 3 to retain the wings in their extended positions.

The Packard Diesel Engine

In a nine‐cylinder radial compression‐ignition engine, a single venturi passage 15 which serves for the admission of air and the exhaust of each cylinder is controlled by a valve 17 opened through a pushrod 19, and fuel is discharged through a nozzle, Fig. 8, controlled by a spring‐loaded valve 30 held off its seat by a stop 33. Fuel for all the cylinders is circulated through a manifold 40 and is delivered to the pumps through ports 41. Fuel is trapped by a plunger 39 and forced past a pair of non‐return valves 38 and a passage 34 to its appropriate fuel nozzle. The plunger is withdrawn by a spring 42, its forcing stroke being effected by a link 44 which bears on a camactuated lever 50, 51, 52. The stroke of the plunger is adjusted by toothed gearing 47, 48 which rotates a ring 46 carrying links 45 pivoted to the links 44. The fuel‐pump actuating cam 54 has four lobes and is driven through gearing 59 . . 62 at one‐eighth the speed of the crank shaft; this cam also operates the cylinder valves 17. The pumps may also be driven by a cam 73 having a single lobe and rotating at the speed of the crank shaft to which it is keyed. The high‐speed single‐lobe cam is operative when starting and times the fuel injection to occur just before top dead‐centre whereas the cam 54 times the injection so that it occurs 40 deg. to 20 deg. before the top dead‐centre. The starting gear comprises a motor 24 having a sliding dog clutch 25 which engages jaws 77 on a sleeve 76 mounted in a second sleeve 75. The sleeves are held against relative axial movement, but are each provided with diametrically opposed inclined slots 78, 79, Fig. 7, which impart to them a relative rotational movement. A pin 80 projects through the two slots into grooves 81 at the end of the crank shaft, and a spring 82 in the hollow portion of the crank shaft bears against a carrier 83 through which the pin 80 projects. During normal running, when the cam 54 actuates the plungers, the spring 82 forces the carrier 83 and the pin 80 to extend the sleeves 75, 76 to their rearmost position. The lobes on the cams 73, 54 are so arranged relatively that the one which is effective will shield the other from the levers 50, 51, 52. At starting, the jaw 25 is moved into engagement with the jaw 77 and the pin SO moves in its axial groove 81 to rotate the sleeves 75, 76 without imparting rotation to the crank shaft. The rotation of the sleeve 75 places the cam 54 in a retarded position so that its cam lobes are ineffective and pass under the lobe on the cam 73. As a consequence the speed of the fuel injection is increased, and as the engine starts the crank shaft overruns the jaw 25 and the spring 82 forces the sleeves 75, 76 and the pin SO to their rearmost position to establish normal running. The shifting of the cam 54 retards the actuating cam lobe 70 of the air inlet valve so that at starting the closing of the air inlet valve is delayed to allow part of the air charge to escape.