Cement brand and preparation effects cement-in-cement mantle shear strength

Creating bi-laminar cement mantles as part of revision hip arthroplasty is well-documented but there is a lack of data concerning the effect of cement brand on the procedure. The aim of this study was to compare the shear strength of bi-laminar cement mantles using various combinations of two leading bone cement brands. Bi-laminar cement mantles were created using Simplex P with Tobramycin, and Palacos R+G: Simplex-Simplex (SS); Simplex-Palacos (SP); Palacos-Simplex (PS); and Palacos-Palacos (PP). Additionally, specimens were produced by rasping (R) the surface of the original mantle, or leaving it unrasped (U), leading to a total of eight groups (n = 10). Specimens were loaded in shear, at 0.1 mm/min, until failure, and the maximum shear strength calculated. The highest mean shear strength was found in the PSU and PSR groups (23.69 and 23.89 MPa respectively), and the lowest in the PPU group (14.70 MPa), which was significantly lower than all but two groups. Unrasped groups generally demonstrated greater standard error than rasped groups. In a further comparison to assess the effect of the new cement mantle brand, irrespective of the brand of the original mantle, Simplex significantly increased the shear strength compared to Palacos with equivalent preparation. It is recommended that the original mantle is rasped prior to injection of new cement, and that Simplex P with Tobramycin be used in preference to Palacos R+G irrespective of the existing cement type. Further research is needed to investigate more cement brands, and understand the underlying mechanisms relating to cement-in-cement procedures. </jats:p

Non-invasive vibrometry-based diagnostic detection of acetabular cup loosening in Total Hip Replacement (THR)

This is the author's accepted manuscript. The final version is available from Elsevier via the DOI in this recordTotal hip replacement is aimed at relieving pain and restoring function. Currently, imaging techniques are primarily used as a clinical diagnosis and follow-up method. However, these are unreliable for detecting early loosening, and this has led to the proposal of novel techniques such as vibrometry. The present study had two aims, namely, the validation of the outcomes of a previous work related to loosening detection, and the provision of a more realistic anatomical representation of the clinical scenario. The acetabular cup loosening conditions (secure, and 1 and 2 mm spherical loosening) considered were simulated using Sawbones composite bones. The excitation signal was introduced in the femoral lateral condyle region using a frequency range of 100–1500 Hz. Both the 1 and 2 mm spherical loosening conditions were successfully distinguished from the secure condition, with a favourable frequency range of 500–1500 Hz. The results of this study represent a key advance on previous research into vibrometric detection of acetabular loosening using geometrically realistic model, and demonstrate the clinical potential of this technique.This study was funded by the Saudi Food and Drug Authority-Medical Devices Sector Scholarship Reference (SFDA026

Non-invasive vibrometry-based diagnostic detection of acetabular cup loosening in Total Hip Replacement (THR)

Total hip replacement is aimed at relieving pain and restoring function. Currently, imaging techniques are primarily used as a clinical diagnosis and follow-up method. However, these are unreliable for detecting early loosening, and this has led to the proposal of novel techniques such as vibrometry. The present study had two aims, namely, the validation of the outcomes of a previous work related to loosening detection, and the provision of a more realistic anatomical representation of the clinical scenario. The acetabular cup loosening conditions (secure, and 1 and 2 mm spherical loosening) considered were simulated using Sawbones composite bones. The excitation signal was introduced in the femoral lateral condyle region using a frequency range of 100–1500 Hz. Both the 1 and 2 mm spherical loosening conditions were successfully distinguished from the secure condition, with a favourable frequency range of 500–1500 Hz. The results of this study represent a key advance on previous research into vibrometric detection of acetabular loosening using geometrically realistic model, and demonstrate the clinical potential of this technique.<br/

The SCJ’s reference systems on scapula (acromionclavicular) and clavicle (sternoclavicular) joints and their coupling functions driven by humeral elevation.

<p>The sternoclavicular joint origin on the sternal extremity of the clavicle and its reference system were designed to allow depression/elevation rotation about the x-axis, protraction/retraction rotations about the y-axis, and axial rotation about the z-axis. The motion of this joint is driven by the humeral elevation via 3 coordinate-coupler constraints based on spline functions. The acromionclavicular joint was designed with a glenoid-based reference system which allows lateral/medial rotation on x-axis, protraction/retraction rotations on y-axis, and anterior-posterior tilt on z-axis. The glenoid based system had the z-axis perpendicular to the glenoid plane, the y-axis directed superiorly toward the superior glenoid tubercle, and the x-axis directed anteriorly perpendicular to the other 2 axes. The motion of the acromionclavicular joint is driven by the sternoclavicular joint motion via 3 coordinate-coupler constraints based on linear functions.</p

Mass distribution of the MASI derived from previous models and values from <i>in vitro</i> study [43].

<p>Mass distribution of the Rugby Model calculated from DEXA values of a rugby forward player (1.84 m; 120.4 Kg). Masses are reported as percentage of total body mass. The principal moment of inertia (I_XX, I_YY, I_ZZ) for the Rugby Model are shown in the las three columns of the table, and are expressed in kgm².</p

Sternoclavicular (SC) (left column) and acromioclavicular (AC) (middle and right columns) motions during humeral elevation.

<p>The black diamonds in the left and middle columns graphs represent SC and AC kinematics during <i>in vivo</i> measurements [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0169329#pone.0169329.ref040" target="_blank">40</a>], whereas black solid lines are the respective SC and AC kinematics generated by the SCJ. The SC and AC joints angles (black solid line) are within 2SD from <i>in vivo</i> values [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0169329#pone.0169329.ref040" target="_blank">40</a>] (black dotted lines). In the right column graphs, the AC kinematics generated by SCJ is compared with another <i>in vivo</i> study and an <i>in silico</i> study. The AC motions generated by the SCJ (black solid line) is within 2SD (black dotted lines) from <i>in vivo</i> studies in the literature [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0169329#pone.0169329.ref041" target="_blank">41</a>] (black squares) and comparable to the output of the Holzbaur’s model [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0169329#pone.0169329.ref026" target="_blank">26</a>] (black dash-dot line). The glenoid reference system of the scapula was roto-traslated in order to express scapula motion with respect to the acromioclavicular joint reference system, and compare it with Ludewig, Hassett (42) and Holzbaur, Murray (26) studies.</p

MASI

Provides the MASI (.osim) file that can be used in OpenSim.<div><br></div><div> <p>The ‘Musculoskeletal model for the Analysis of Spinal Injury’ (MASI) wascreated in OpenSim (OpenSim 3.2, Simbios, Stanford, CA, USA) and Matlab software (Matlab 2013b, MathWorks, Natick, MA, USA).</p><p>MASI inherited the structure of the OpenSim head and neck model (Vasavada Model) which we embedded into a full body model (‘2354’), and was implemented to provide, for the first time, the linkage between cervical spine, upper limb, torso and lower limbs. </p><p>MASI comprises 35 rigid anatomical segments, 78 upper and lower cervical muscles divided into 19 muscle groups, along with 23 torque actuators representing lower and upper limb muscles’ actions. Motion between body segments was permitted via 34 joints and 30 kinematic constraints. To incorporate the effect of upper limb position, a new scapula-clavicular joint (SCJ) (combining the joint motions of the acromioclavicular and sternoclavicular joints) was developed and included in the MASI, replacing the welded scapula-clavicular joint of the original head and neck model. The model had 43 degrees of freedom, though these were reduced to 37 by locking the metatarsophalangeal and wrist joints into the neutral position.</p> </div

Cervical Spine Injuries: A Whole-Body Musculoskeletal Model for the Analysis of Spinal Loading - Fig 8

<p>(A) The three main phases of a rugby scrummaging activity: pre-engagement phase, engagement phase, and sustained-push. (B) Average flexion-extension joint angle across cervical spine joints during ‘Pre-Eng’ and ‘Engagement’ phases. Extension motion is positive in the graph. (C) Flexion-extension joint moment values during pre-engagement and engagement phases across the cervical spine vertebral joints. Extensor moment is positive in the graph. The graph shows the decreasing pattern of extensor moment from C7-C6 joint to C1-Head, which is mainly due to resist the flexion moment generate by the gravity force.</p

Neck strength values are reported from <i>in vivo</i> and <i>in silico</i> studies.

<p>Extension (<i>Ext</i>), flexion (<i>Flex</i>), axial rotation (<i>Axial Rot</i>), and lateral bending (<i>Lat Bend</i>) scaling factors are shown for adult rugby players (Rugby Front Row) and adult healthy males (Healthy Male). The scaling factors used to scale the MASI and Rugby Model neck muscles are calculated independently for flexors and extensors in order to match maximum extension and lateral bending neck strength values for a healthy male (Healthy Male) and a front row rugby player (Rugby Front Row), respectively. Head-Neck Model [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0169329#pone.0169329.ref030" target="_blank">30</a>] was used as scaling reference, thus its scaling factor is 1.</p

Rugby Model simulated neck muscle activation.

<p>Simulated muscle activation from computed muscle control (solid black line) and experimental EMG (dashed black line) of sternocleidomastoid (left column) and upper trapezius (right column) muscles during flexion, extension, lateral bending (right and left bending) and axial rotation (right and left rotation). Experimental EMG signal were normalized using maximum voluntary contraction data and defined between 0% and 100%. Simulated activations are defined between 0% (no activation) and 100% (full activation).</p