R. Gill - Academia.edu (original) (raw)

Papers by R. Gill

$Research paper thumbnail of Comparison of torque resistance between three fractured neck of femur fixation devices$

Introduction: The global figure of people above the age of fifty who sustained hip fractures in 1... more Introduction: The global figure of people above the age of fifty who sustained hip fractures in 1990 was 1.7 million. Cooper et al [1] estimated that this figure could be as high as 6.3 million per year by 2050. A more recent study carried out by Gulberg et al [2] gives a more conservative prediction of the total number of hip fractures as 2.6 million by 2025 and 4.5 million by 2050; but these still represent significant numbers. Hip screws are predominantly used for the treatment of fractures of the proximal femur (AO 31). This includes the fractures of the trochanteric area (AO 31-A) and the femoral neck (AO 31-B). Data from the United States suggests that 49% of all hip fractures are intertrochanteric making it the most common type. [3] Using standard notation, A0 31-A3 is the most common hip fracture. This condition is often treated using the Dynamic Hip Screw (DHS). Failure rates of the DHS vary between 5% [4, 5] and 23% [6], with cutout being the most common mode of failure. Fixation with the DHS does not provide optimal rotational stability and a number of newer fixation devices have emerged to address this, with the DHS Blade (Synthes Ltd, Welwyn Garden City, UK) and X-Bolt (X-Bolt Direct Ltd, Bristol, UK) being two recent designs. The aim of the present study was to evaluate the rotational stability, using polyurethane foam bone analogue, of these newer designs compared to the DHS (Synthes Ltd). Null Hypothesis: The DHS Blade and X-Bolt have the same torsional stability as the DHS hip fracture fixation device. Methods: A torque test protocol was established to determine the torque resistance of the three hip fracture fixation devices. This study used polyurethane (PU) foam (Sawbones, Malmo, Sweden) bone analogue blocks (47 mm x 47 mm x 40 mm) of three different densities (D1=0.08, D2=0.16, D3=0.24 g/cm3) representative of highly (D1), moderately (D2) and mildly (D3) osteoporotic bone[7]. A perpendicular hole was drilled a depth of 35 mm into each block and then the fixation devices were inserted, using the manufacturer recommended insertion protocols and instruments. The constructs were then mounted, using custom fittings, in a bi-axial material test machine (HBT 25-200, Zwick Testing Machines Ltd., Leominster, UK). The PU foam blocks were held fixed and the fixation devices were mounted in the rotating end effector of the test machine. A ramp torque of 1°/minute was then applied whilst the torque and angular displacement achieved were recorded at a sampling frequency of 10 Hz. The data were then filtered using a third order Butterworth low-pass filter with 1 Hz cutoff frequency (Matlab R2012, The MathWorks, Natick, MA, USA). The primary outcome measures were the work done to achieve 6° of rotation, calculated from the area under the torque/displacement curve, and the peak torque achieved. For each fixation device five trials at each foam density were performed. Non-parametric statistical analysis (SPSS, IBM, New York, NY, USA) was then performed, first comparing the work done and peak torque between devices for each foam density level (Kruskal Wallis [KW] test), and then comparing the same variables between density levels for each device. When statistical significance (p≤0.05) was found, further Mann-Whitney U (MW) tests were performed to compare between various paired combinations of devices and densities. Results: The overall trend for both the work done (Figure 1, Table 1) and the peak torque (Figure 2, Table 1) was for these values to increase as density of the PU foam increased. Generally highest values for both variables were seen for the X-Bolt, the next highest for the DHS Blade and the lowest for the DHS. For work done the differences between devices were significant only for densities D1 (KW p=0.013) and D2 (KW p=0.002). For peak torque there were significant differences at all densities (D1: KW p=0.006, D2: KW p=0.002, D3: KW p=0.015). Comparing the X-Bolt and the DHS, the X-Bolt had significantly larger values for work done than the DHS for densities D1 (MW p=0.008) and D2 (MW p=0.008), whilst peak torque was significantly higher for the X-Bolt at all densities (D1: MW p=0.008, D2: MW p=0.008, D3: MW p=0.032). Comparing the DHS Blade and the DHS, the DHS Blade had significantly larger values for work done than the DHS for densities D1 (MW p=0.016) and D2 (MW p=0.008), this was also the case for the peak torque (D1: MW p=0.008, D2: MW p=0.008). Comparing the X-Bolt and the DHS Blade, the X-Bolt had significantly larger values for work done than the DHS Blade for density D2 (MW p=0.008), whilst peak torque was significantly higher for the X-Bolt at densities D2 (MW p=0.008) and D3 (MW p=0.008). Examining the differences for each device for the three different foam densities showed that there were only significant differences for the X-Bolt (work done KW p=0.009, peak torque KW p=0.008) and the DHS (work done KW p=0.004, peak torque KW p=0.005).

Knee, Aug 1, 2021

Background This paper describes the evolutionary changes in morphology and orientation of the PFJ... more Background This paper describes the evolutionary changes in morphology and orientation of the PFJ using species present through our ancestry over 340 million years. Methods 37 specimens from the Devonian period to modern day were scanned using a 64-slice CT scanner. 3D geometries were created following routine segmentation and anatomical measurements taken from standardised bony landmarks. Results Findings are described according to gait strategy and age. The adoption of an upright bi-pedal stance caused a dramatic change in the loading of the PFJ which has subsequently led to changes in the arrangement of the PFJ. From Devonian to Miocene periods, our sprawling and climbing ancestors possessed a broad knee with a shallow, centrally located trochlea. A more rounded knee was present from the Paleolithic period onwards in erect and bipedal gait types (aspect ratio 0.93 vs 1.2 in late Devonian), with the PFJ being placed lateral to the midline compared to the medial position in quadrapeds. The depth of the trochlea groove was maximal in the Miocene period of the African ground apes with associated acute sulcus angles in Gorilla (117°) becoming more flattened towards the modern human (138°). Conclusions The evolving bipedal gait lead to anteriorisation of the patellofemoral joint, flattening of the trochlea sulcus, in a more lateral, dislocation prone arrangement. Ancestral developments might help explain the variety of presentations of anterior knee pain and patellofemoral instability.

Materials

Cervical spine injuries (CSIs) arising from collisions are uncommon in contact sports, such as ru... more Cervical spine injuries (CSIs) arising from collisions are uncommon in contact sports, such as rugby union, but their consequences can be devastating. Several FE modelling approaches are available in the literature, but a fully calibrated and validated FE modelling framework for cervical spines under compressive dynamic-impact loading is still lacking and material properties are not adequately calibrated for such events. This study aimed to develop and validate a methodology for specimen-specific FE modelling of vertebral bodies under impact loading. Thirty-five (n = 35) individual vertebral bodies (VBs) were dissected from porcine spine segments, potted in bone cement and μCT scanned. A speckle pattern was applied to the anterior faces of the bones to allow digital image correlation (DIC), which monitored the surface displacements. Twenty-seven (n = 27) VBs were quasi-statically compressively tested to a load up to 10 kN from the cranial side. Specimen-specific FE models were devel...

Provides the MASI (.osim) file that can be used in OpenSim.<br> The 'Musculoskeletal mo... more Provides the MASI (.osim) file that can be used in OpenSim.<br> 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).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. 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 ...

This version is made available in accordance with publisher policies. Please cite only the publis... more This version is made available in accordance with publisher policies. Please cite only the published version using the reference above.

$Research paper thumbnail of The effect of bridging span and fracture healing on the performance of high tibial osteotomy plates$

Journal of Biomechanical Engineering, 2021

Knowledge of neck muscle activation strategies before sporting impacts is crucial for investigati... more Knowledge of neck muscle activation strategies before sporting impacts is crucial for investigating mechanisms of severe spinal injuries. However, measurement of muscle activations during impacts is experimentally challenging and computational estimations are not often guided by experimental measurements. We investigated neck muscle activations before impacts with the use of electromyography (EMG)-assisted neuromusculoskeletal models. Kinematics and EMG recordings from four major neck muscles of a rugby player were experimentally measured during rugby activities. A subject-specific musculoskeletal model was created with muscle parameters informed from MRI measurements. The model was used in the calibrated EMG-informed neuromusculoskeletal modeling toolbox and three neural solutions were compared: (i) static optimization (SO), (ii) EMG-assisted (EMGa), and (iii) MRI-informed EMG-assisted (EMGaMRI). EMGaMRI and EMGa significantly (p < 0.01) outperformed SO when tracking cervical sp...

Journal of Orthopaedic Research, 2020

Additive manufacturing, aka three dimensional (3D) printing, is increasingly being used for perso... more Additive manufacturing, aka three dimensional (3D) printing, is increasingly being used for personalized orthopedic implants. Additively manufactured components normally undergo further processing, in particular 3D printed locking osteosynthesis plates require post‐printing screw thread creation. The aim of this study was to compare 3D printed threads with machined and hand‐tapped threads for a locking plate application. Pushout tests were performed on 115 additively manufactured specimens with tapered screw holes; additive manufacture was performed at 0°, 20°, 45°, or 90° build orientations. The screw holes were either machined, hand‐tapped or 3D printed. The 3D printed screw holes were left as printed, or run through with a tap lubricated with water or with thread cutting oil. Printed threads run through using oil, with a build orientation of 90°, had comparable pushout force (median: 6377 N 95% confidence interval [CI]: 5616‐7739 N) to machined (median: 6757 N; 95% CI: 6682‐7303 ...

Bone & Joint Research, 2020

Aims To devise a method to quantify and optimize tightness when inserting cortical screws, based ... more Aims To devise a method to quantify and optimize tightness when inserting cortical screws, based on bone characterization and screw geometry. Methods Cortical human cadaveric diaphyseal tibiae screw holes (n = 20) underwent destructive testing to firstly establish the relationship between cortical thickness and experimental stripping torque (Tstr), and secondly to calibrate an equation to predict Tstr. Using the equation’s predictions, 3.5 mm screws were inserted (n = 66) to targeted torques representing 40% to 100% of Tstr, with recording of compression generated during tightening. Once the target torque had been achieved, immediate pullout testing was performed. Results Cortical thickness predicted Tstr (R2 = 0.862; p < 0.001) as did an equation based on tensile yield stress, bone-screw friction coefficient, and screw geometries (R2 = 0.894; p < 0.001). Compression increased with screw tightness up to 80% of the maximum (R2 = 0.495; p < 0.001). Beyond 80%, further tighten...

Journal of Biomaterials Applications, 2020

Ultra-high molecular weight polyethylene has a low X-ray attenuation, hence, the performance of t... more Ultra-high molecular weight polyethylene has a low X-ray attenuation, hence, the performance of the polyethylene implants used for joint replacements cannot be directly investigated using X-ray-based imaging techniques. In this study, the X-ray attenuation of polyethylene was increased by diffusing an FDA-approved oil-based contrast agent (Lipiodol ultra fluid) into the surface of the samples, and the suitability of this novel radiopaque ultra-high molecular weight polyethylene for clinical applications was examined. Different levels of radiopacity were created by controlling the diffusion parameters, and the level of radiopacity was quantified from computed tomography scans and reported in Hounsfield units. The physical, chemical and tensile properties of the radiopaque ultra-high molecular weight polyethylene were examined and compared to untreated and thermally treated controls. The results of this study confirmed that for the samples treated at 115°C or less the diffusion of the...

$Research paper thumbnail of The effect of plate design, bridging span, and fracture healing on the performance of high tibial osteotomy plates$

Bone & Joint Research, 2018

Objectives Opening wedge high tibial osteotomy (HTO) is an established surgical procedure for the... more Objectives Opening wedge high tibial osteotomy (HTO) is an established surgical procedure for the treatment of early-stage knee arthritis. Other than infection, the majority of complications are related to mechanical factors – in particular, stimulation of healing at the osteotomy site. This study used finite element (FE) analysis to investigate the effect of plate design and bridging span on interfragmentary movement (IFM) and the influence of fracture healing on plate stress and potential failure. Materials and Methods A 10° opening wedge HTO was created in a composite tibia. Imaging and strain gauge data were used to create and validate FE models. Models of an intact tibia and a tibia implanted with a custom HTO plate using two different bridging spans were validated against experimental data. Physiological muscle forces and different stages of osteotomy gap healing simulating up to six weeks postoperatively were then incorporated. Predictions of plate stress and IFM for the cust...

The American journal of sports medicine, 2018

A simple suture technique in transosseous meniscal root repair can provide equivalent resistance ... more A simple suture technique in transosseous meniscal root repair can provide equivalent resistance to cyclic load and is less technically demanding to perform compared with more complex suture configurations, yet maximum yield loads are lower. Various suture materials have been investigated for repair, but it is currently not clear which material is optimal in terms of repair strength. Meniscal root anatomy is also complex; consisting of the ligamentous mid-substance (root ligament), the transition zone between the meniscal body and root ligament; the relationship between suture location and maximum failure load has not been investigated in a simulated surgical repair. (A) Using a knottable, 2-mm-wide, ultra-high-molecular-weight polyethylene (UHMWPE) braided tape for transosseous meniscal root repair with a simple suture technique will give rise to a higher maximum failure load than a repair made using No. 2 UHMWPE standard suture material for simple suture repair. (B) Suture positio...

PloS one, 2017

Cervical spine trauma from sport or traffic collisions can have devastating consequences for indi... more Cervical spine trauma from sport or traffic collisions can have devastating consequences for individuals and a high societal cost. The precise mechanisms of such injuries are still unknown as investigation is hampered by the difficulty in experimentally replicating the conditions under which these injuries occur. We harness the benefits of computer simulation to report on the creation and validation of i) a generic musculoskeletal model (MASI) for the analyses of cervical spine loading in healthy subjects, and ii) a population-specific version of the model (Rugby Model), for investigating cervical spine injury mechanisms during rugby activities. The musculoskeletal models were created in OpenSim, and validated against in vivo data of a healthy subject and a rugby player performing neck and upper limb movements. The novel aspects of the Rugby Model comprise i) population-specific inertial properties and muscle parameters representing rugby forward players, and ii) a custom scapula-cl...

PloS one, 2016

Articular cartilage exhibits complex mechano-electrochemical behaviour due to its anisotropy, inh... more Articular cartilage exhibits complex mechano-electrochemical behaviour due to its anisotropy, inhomogeneity and material non-linearity. In this work, the thickness and radial dependence of cartilage properties are incorporated into a 3D mechano-electrochemical model to explore the relevance of heterogeneity in the behaviour of the tissue. The model considers four essential phenomena: (i) osmotic pressure, (ii) convective and diffusive processes, (iii) chemical expansion and (iv) three-dimensional through-the-thickness heterogeneity of the tissue. The need to consider heterogeneity in computational simulations of cartilage behaviour and in manufacturing biomaterials mimicking this tissue is discussed. To this end, healthy tibial plateaus from pigs were mechanically and biochemically tested in-vitro. Heterogeneous properties were included in the mechano-electrochemical computational model to simulate tissue swelling. The simulation results demonstrated that swelling of the heterogeneo...

Clinical orthopaedics and related research, Jan 12, 2015

The Bernese periacetabular osteotomy (PAO) is a recognized joint-preserving procedure. Achieving ... more The Bernese periacetabular osteotomy (PAO) is a recognized joint-preserving procedure. Achieving joint stability without creating impingement is important, but the orientation target that best balances these sometimes competing goals has not yet been clearly defined. Moreover, the learning curve of this challenging procedure has not been described. The purposes of this study were (1) to determine the 10-year survivorship and functional outcome after Bernese PAO in a single-surgeon series; (2) to review which patient, surgical, and radiographic factors might predict outcome after the procedure; and (3) to define the learning curve for target acetabular correction. The first 68 PAOs performed for symptomatic hip dysplasia were retrospectively evaluated. None have been lost to followup with followup less than 2 years. Endpoints for the lost to followup (n = 2) are at the time of when last seen. During the study period, the same surgeon performed 562 pelvic osteotomies (including Salter...

Hip international : the journal of clinical and experimental research on hip pathology and therapy

The objectives of the present study were to determine whether differences in the radiographic app... more The objectives of the present study were to determine whether differences in the radiographic appearance of the of the proximal femoral canal exist on corresponding AP pelvis and AP hip radiographs, and whether radiographic assessment of canal shape is accurate with reference to computed tomography (CT). In a retrospective study, corresponding radiographs and CT scans of 100 consecutive patients with primary hip OA were evaluated. Active shape modelling (ASM) was performed to assess the variation in proximal femoral canal shape and to identify differences between AP hip and AP pelvis views. Differences in the medial cortical flare between radiographs and CT were quantified using least squares curve fitting. ASM identified significant differences in the assessment of canal shape on corresponding AP hip and AP pelvis views. Curve fitting demonstrated a good agreement between AP hip radiographs and CT. Agreement between AP pelvis radiographs and CT was less good. In contrast to AP pelv...

Biomedical optics express, Jan 16, 2013

The collagen meshwork plays a central role in the functioning of a range of tissues including car... more The collagen meshwork plays a central role in the functioning of a range of tissues including cartilage, tendon, arteries, skin, bone and ligament. Because of its importance in function, it is of considerable interest for studying development, disease and regeneration processes. Here, we have used second harmonic generation (SHG) to image human tissues on the hundreds of micron scale, and developed a numerical model to quantitatively interpret the images in terms of the underlying collagen structure on the tens to hundreds of nanometer scale. Focusing on osteoarthritic changes in cartilage, we have demonstrated that this combination of polarized SHG imaging and numerical modeling can estimate fibril diameter, filling fraction, orientation and bundling. This extends SHG microscopy from a qualitative to quantitative imaging technique, providing a label-free and non-destructive platform for characterizing the extracellular matrix that can expand our understanding of the structural mech...