76 results found
Giannas E, Zhang J, Haar R, et al., 2023, Preoperative planning to preserve glenoid subchondral bone in anatomical total shoulder replacement., JSES Int, Vol: 7, Pages: 493-498
BACKGROUND: Glenoid loosening remains a concern in anatomical total shoulder replacement. Preoperative planning software allows optimization of the component positioning, but the target orientation remains unclear due to conflicting optimization priorities. Commonly, the component is aligned to the prescribed version and inclination that reflect the population's average anatomy. The freehand technique attempts to secure strong fixation by aiming to preserve the subchondral bone. This study compared the state of the subchondral plate after reaming and compared the results of these two techniques. METHODS: Two groups of shoulder computed tomography scans were assessed, 34 normal and 34 osteoarthritic. Preoperative planning software was used to place the glenoid component in prescribed adjusted angles, with neutral (0o,0o), retroverted (-10o,0o) and inclined alignment (0o,10o). The computed tomography Hounsfield values at the virtually reamed surface were assessed to determine the percentage of the intended component-bone interface consisting of cortical bone, here termed "cortical bone seating". This was then compared to positioning the component using a freehand technique. RESULTS: The freehand technique improved cortical bone seating in the osteoarthritic group with a mean (standard deviation) of 53.3% (14.3), while neutral alignment resulted in 36.7% (10.8), retroversion 40.4% (13.1), and inclination 39.3% (13.5), P < .001. A similar trend was observed in the normal group. CONCLUSIONS: The freehand method resulted in significantly improved cortical bone seating compared to the prescribed adjusted angles. These findings question the use of a one-size-fits-all-orientation and suggest that applying a technique that aims for maximum cortical fixation (freehand) may reduce the risk of aseptic loosening.
Darwood A, Hurst SA, Villatte G, et al., 2022, Novel robotic technology for the rapid intraoperative manufacture of patient-specific instrumentation allowing for improved glenoid component accuracy in shoulder arthroplasty: a cadaveric study, JOURNAL OF SHOULDER AND ELBOW SURGERY, Vol: 31, Pages: 561-570, ISSN: 1058-2746
Brodén C, Reilly P, Khanna M, et al., 2022, CT-based micromotion analysis method can assess early implant migration and development of radiolucent lines in cemented glenoid components: a clinical feasibility study., Acta Orthop, Vol: 93, Pages: 277-283
BACKGROUND AND PURPOSE: CT micromotion analysis (CTMA) has been considered as an alternative to radiostereometry (RSA) for assessing early implant migration of orthopedic implants. We investigated the feasibility of CTMA to assess early migration and the progression of radiolucent lines in shoulder arthroplasties over 24 months using sequential low-dose CT scans. PATIENTS AND METHODS: 7 patients were included and underwent 9 primary total shoulder arthroplasties. We made CT scans preoperatively, within 1 week postoperatively, and after 3, 6, 12, and 24 months. At each follow-up, postoperative glenoid migration and any development of radiolucent lines were assessed. Clinical outcomes were recorded at all time points except within 1 week postoperatively. RESULTS: For the glenoid component, the median translation and median rotation were 0.00-0.10 mm and -1.53° to 1.05° at 24 months. Radiolucent lines could be observed around all glenoid components. The radiolucent lines developed from the periphery to the center of the implant for 6 glenoid components during follow-up. The Constant Score improved from a mean of 30 (21-51) preoperatively to 69 (41-88) at 24 months. INTERPRETATION: CTMA can be used to identify early migration and the development of radiolucent lines over time in glenoid components. Clinical trials with a larger sample size and longer follow-up are needed to establish the relationship between migration, radiolucent lines, loosening, and clinical outcome.
Giles JW, Broden C, Tempelaere C, et al., 2021, Development and ex-vivo assessment of a novel patient specific guide and instrumentation system for minimally invasive total shoulder arthroplasty, PLOS ONE, Vol: 16, ISSN: 1932-6203
Sharma A, Goring A, Johnson PB, et al., 2021, Multiscale molecular profiling of pathological bone resolves sexually dimorphic control of extracellular matrix composition, DISEASE MODELS & MECHANISMS, Vol: 14, ISSN: 1754-8403
Villatte G, van der Kruk E, Asim B, et al., 2020, A biomechanical confirmation of the relationship between critical shoulder angle (CSA) and articular joint loading, Journal of Shoulder and Elbow Surgery, Vol: 29, Pages: 1967-1973, ISSN: 1058-2746
Background: The Critical Shoulder Angle (CSA) has been shown to be correlated with shoulder disease states. The biomechanical hypothesis to explain this correlation is that the CSA changes the shear and compressive forces on the shoulder. The objective of this study is to test this hypothesis by use of a validated computational shoulder model. Specifically, this study assesses the impact on glenohumeral biomechanics of modifying the CSA. Methods: An inverse dynamics three-dimensional musculoskeletal model of the shoulder was used to quantify muscle forces and glenohumeral joint forces. The CSA was changed by altering the attachment point of the middle deltoid into a normal CSA (33°), a reduced CSA of 28°, and an increased CSA of 38°. Subject-specific kinematics of slow and fast speed abduction in the scapular plane, and slow and fast forward flexion measured by a 3D motion capture system were used to quantify joint reaction shear and compressive forces.Results: Increasing the CSA results in increased superior-inferior forces (shearing forces; integrated over the range of motion; p<0.05). Reducing CSA results in increased latero-medial (compressive) forces for both the maximum and integrated sum of the forces over the whole motion; p<0.01).Discussion/Conclusion: Changes in the CSA modify glenohumeral joint biomechanics with increasing CSA producing higher shear forces that would contribute to rotator cuff overuse, whereas reducing the CSA results in higher compressive forces which contribute to joint wear.
Ajdari N, Tempelaere C, Masouleh MI, et al., 2020, Hemiarthroplasties: the choice of prosthetic material causes different levels of damage in the articular cartilage, Journal of Shoulder and Elbow Surgery, Vol: 29, Pages: 1019-1029, ISSN: 1058-2746
Background Hemiarthroplasty has clear advantages over alternative procedures and is used in 20% of all shoulder joint replacements. Because of cartilage wear, the clinical outcome of hemiarthroplasty is unreliable and controversial. This paper suggests that the optimal choice of prosthetic material may reduce cartilage degeneration and improve the reliability of the procedure. The specific objectives were to assess 3 materials and assess how the severity of arthritis might affect the choice of prosthetic material. Methods A CoCr alloy, an AL2O3 ceramic, and a polycarbonate urethane polymer (PCU) were mechanically tested against 5 levels of human osteoarthritic cartilage (from intact to severely arthritic, n = 45). A high friction coefficient, a decrease in Young's modulus, an increase in permeability, a decrease in relaxation time, an increase in surface roughness, and a disrupted appearance of the cartilage after testing were used as measures of cartilage damage. The biomaterial that caused minimal cartilage damage was defined as superior. Results The CoCr caused the most damage. This was followed by the AL2O3 ceramic, whereas the PCU caused the least amount of damage. Although the degree of arthritis had an effect on the results, it did not change the trend that CoCr performed worst and PCU the best. Discussion and Conclusion This study indicates that ceramic implants may be a better choice than metals, and the articulating surface should be as smooth as possible. Although our results indicate that the degree of arthritis should not affect the choice of prosthetic material, this suggestion needs to be further investigated.
Sharma A, Goring A, Staines KA, et al., 2020, Raman spectroscopy links differentiating osteoblast matrix signatures to pro-angiogenic potential., Matrix Biol Plus, Vol: 5
Mineralization of bone is achieved by the sequential maturation of the immature amorphous calcium phase to mature hydroxyapatite (HA) and is central in the process of bone development and repair. To study normal and dysregulated mineralization in vitro, substrates are often coated with poly-l-lysine (PLL) which facilitates cell attachment. This study has used Raman spectroscopy to investigate the effect of PLL coating on osteoblast (OB) matrix composition during differentiation, with a focus on collagen specific proline and hydroxyproline and precursors of HA. Deconvolution analysis of murine derived long bone OB Raman spectra revealed collagen species were 4.01-fold higher in OBs grown on PLL. Further, an increase of 1.91-fold in immature mineral species (amorphous calcium phosphate) was coupled with a 9.32-fold reduction in mature mineral species (carbonated apatite) on PLL versus controls. These unique low mineral signatures identified in OBs were linked with reduced alkaline phosphatase enzymatic activity, reduced Alizarin Red staining and altered osteogenic gene expression. The promotion of immature mineral species and restriction of mature mineral species of OB grown on PLL were linked to increased cell viability and pro-angiogenic vascular endothelial growth factor (VEGF) production. These results demonstrate the utility of Raman spectroscopy to link distinct matrix signatures with OB maturation and VEGF release. Importantly, Raman spectroscopy could provide a label-free approach to clinically assess the angiogenic potential of bone during fracture repair or degenerative bone loss.
Majed A, Thangarajah T, Southgate DFL, et al., 2019, The biomechanics of proximal humeral fractures: Injury mechanism and cortical morphology, Shoulder & Elbow, Vol: 11, Pages: 247-255, ISSN: 1758-5732
BackgroundThe aim of this study was to examine the effect of arm position on proximal humerus fracture configuration and to determine whether cortical thinning would predispose to fracture propagation and more complex patterns of injury.MethodsA drop test rig was designed to simulate falls onto an outstretched arm (‘parachute reflex’). Thirty-one cadaveric specimens underwent computer tomography scanning and cortical thicknesses mapping. Humeri were fractured according to one of the two injury mechanisms and filmed using a high-speed camera. Anatomical descriptions of the injuries were made. Areas of thinning were measured and correlated with zones of fracture propagation.ResultsDirect impact simulation resulted in undisplaced humeral head split fractures in 53% of cases, with the remainder involving disruption to the articular margin and valgus impaction. Alternatively, the ‘parachute reflex’ predominantly produced shield-type injuries (38%) and displaced greater tuberosity fractures (19%). A strong correlation was demonstrated between cortical thinning and the occurrence of fracture (odds ratio = 7.766, 95% confidence interval from 4.760 to 12.669, p<0.0001).ConclusionThis study has shown that arm position during a fall influences fracture configuration of the proximal humerus. Correlating fracture pattern and mechanism of injury will allow more appropriate fracture reduction techniques to be devised.
Thompson SM, Prinold JAI, Hill AM, et al., 2019, The influence of full-thickness supraspinatus tears on abduction moments: the importance of the central tendon, Shoulder and Elbow, Vol: 11, Pages: 19-25, ISSN: 1758-5740
Background: Detachment of the central tendon of the supraspinatus from its insertion is considered to be crucial to functional deficit. The aim of the present study was to assess the function of the supraspinatus in terms of abduction moments by introducing different tear configurations to assess the functional effect of the central tendon insertion. Methods: Ten fresh frozen shoulders from five cadavers were prepared for testing. A testing protocol was established to measure the abduction moment of the supraspinatus under physiological loading tailored to the anthropometrics of each specimen. Four conditions were tested: intact supraspinatus; complete detachment of portion of the supraspinatus tendon anterior to the main central tendon; detachment of the main central tendon; and detachment of the region of the supraspinatus posterior to the main central tendon. Results: There was a significant and large reduction in abduction moment when the central tendon was sectioned (p < 0.05). A smaller reduction in abduction moment was found when the regions anterior and posterior to the main central tendon were sectioned (p < 0.05). Conclusions: The central tendon is vital in the role of functional arm abduction through force transmission through the intact rotator cuff. Reinsertion of the central tendon in the correct anatomical location is desirable to optimize functional outcome of surgery.
Majed A, Thangarajah T, Southgate D, et al., 2019, Cortical thickness analysis of the proximal humerus., Shoulder Elbow, Vol: 11, Pages: 87-93, ISSN: 1758-5732
BACKGROUND: Structural changes within the proximal humerus influence the mechanical properties of the entire bone and predispose to low-energy fractures with complex patterns. The aim of the present study was to measure the cortical thickness in different regions of the proximal humerus. METHODS: Thirty-seven proximal humeri were analyzed using novel engineering software to determine cortical thickness in 10 distinct anatomical zones. RESULTS: The cortical thickness values ranged from 0.33 mm to 3.5 mm. Fifteen specimens demonstrated a consistent pattern of progressive cortical thinning that increased between the bicipital groove (thickest), the lesser tuberosity and the greater tuberosity (thinnest). Fifteen humeri were characterized by a progressive increase in cortical thickness between the greater tuberosity (thinnest), the bicipital groove and lesser tuberosity (thickest). The diaphysis exhibited the thickest cortical zone in 27 specimens, whereas the articular surface possessed the thinnest cortex in 18 cases. CONCLUSIONS: In conclusion, this is the first study to comprehensively assess cortical thickness of the humeral head. Our findings suggest that proximal humeral fractures occur along lines of cortical thinning and are displaced by the hard glenoid bone. The identification of specific areas of thick cortices may improve pre-operative planning and optimize fracture fixation.
Villatte G, Spurr S, Broden C, et al., 2018, The Eden-Hybbinette procedure is one hundred years old! A historical view of the concept and its evolutions, INTERNATIONAL ORTHOPAEDICS, Vol: 42, Pages: 2491-2495, ISSN: 0341-2695
Junaid S, Gregory T, Fetherston S, et al., 2018, Cadaveric study validating in vitro monitoring techniques to measure the failure mechanism of glenoid implants against clinical CT, Journal of Orthopaedic Research, Vol: 36, Pages: 2524-2532, ISSN: 0736-0266
Definite glenoid implant loosening is identifiable on radiographs, however, identifying early loosening still eludes clinicians. Methods to monitor glenoid loosening in vitro have not been validated to clinical imaging. This study investigates the correlation between in vitro measures and CT images. Ten cadaveric scapulae were implanted with a pegged glenoid implant and fatigue tested to failure. Each scapulae were cyclically loaded superiorly and CT scanned every 20,000 cycles until failure to monitor progressive radiolucent lines. Superior and inferior rim displacements were also measured. A finite element (FE) model of one scapula was used to analyze the interfacial stresses at the implant/cement and cement/bone interfaces. All ten implants failed inferiorly at the implant-cement interface, two also failed at the cement-bone interface inferiorly, and three showed superior failure. Failure occurred at of 80,966 ± 53,729 (mean ± SD) cycles. CT scans confirmed failure of the fixation, and in most cases, was observed either before or with visual failure. Significant correlations were found between inferior rim displacement, vertical head displacement and failure of the glenoid implant. The FE model showed peak tensile stresses inferiorly and high compressive stresses superiorly, corroborating experimental findings. In vitro monitoring methods correlated to failure progression in clinical CT images possibly indicating its capacity to detect loosening earlier for earlier clinical intervention if needed. Its use in detecting failure non-destructively for implant development and testing is also valuable. The study highlights failure at the implant-cement interface and early signs of failure are identifiable in CT images. © 2018 The Authors. Journal of Orthopaedic Research® Published by Wiley Periodicals, Inc. on behalf of the Orthopaedic Research Society. J Orthop Res 9999:XX-XX, 2018.
Villatte G, Muller A-S, Pereira B, et al., 2018, Use of Patient-Specific Instrumentation (PSI) for glenoid component positioning in shoulder arthroplasty. A systematic review and meta-analysis, PLOS ONE, Vol: 13, ISSN: 1932-6203
Majed A, Thangarajah T, Krekel P, et al., 2018, Simulation of bone-determined range of motion in proximal humeral fractures., Shoulder Elbow, Vol: 10, Pages: 186-191, ISSN: 1758-5732
Background: Predicting the outcome following fractures of the proximal humerus is an important consideration when effectively counselling patients and planning treatment. The purpose of the present study was to analyze different proximal humeral fracture configurations, using a computerized simulation model, aiming to predict the range of motion (ROM). Methods: The computer tomography scans of 79 proximal humeral fractures were analyzed using a customized software system that simulated the range of movement at the glenohumeral joint. Four fracture patterns were investigated: (1) head split fractures; (2) greater tuberosity fractures; (3) lesser tuberosity fractures; and (4) combined tuberosity fractures. Results: Intra-articular fractures had the smallest mean (SE) range of abduction and forward flexion [34.3° (6.6°) and 60.7° (12.4°)]. Isolated displaced greater tuberosity resulted in limited abduction but not forward flexion [75.0° (5.9°) and 118.2° (4.9°)]. Isolated lesser tuberosity fractures displayed a ROM comparable to that of healthy subjects [89.3° (3.3°) and 122.6° (3.4°) versus 102.3° (2.8°) and 96.2° (3.8°)]. The reduced head inclination angle was a relatively strong predictor of a limited range of abduction for all fracture types. Conclusions: The present study describes a novel simulation system used to quantify the bone-determined ROM in proximal humeral fractures and may be a useful adjunct in the diagnostic armamentarium for proximal humeral fractures.
Kwasnicki RM, Cross GW, Geoghegan L, et al., 2018, A lightweight sensing platform for monitoring sleep quality and posture: a simulated validation study, EUROPEAN JOURNAL OF MEDICAL RESEARCH, Vol: 23, ISSN: 0949-2321
BackgroundThe prevalence of self-reported shoulder pain in the UK has been estimated at 16%. This has been linked with significant sleep disturbance. It is possible that this relationship is bidirectional, with both symptoms capable of causing the other. Within the field of sleep monitoring, there is a requirement for a mobile and unobtrusive device capable of monitoring sleep posture and quality. This study investigates the feasibility of a wearable sleep system (WSS) in accurately detecting sleeping posture and physical activity.MethodsSixteen healthy subjects were recruited and fitted with three wearable inertial sensors on the trunk and forearms. Ten participants were entered into a ‘Posture’ protocol; assuming a series of common sleeping postures in a simulated bedroom. Five participants completed an ‘Activity’ protocol, in which a triphasic simulated sleep was performed including awake, sleep and REM phases. A combined sleep posture and activity protocol was then conducted as a ‘Proof of Concept’ model. Data were used to train a posture detection algorithm, and added to activity to predict sleep phase. Classification accuracy of the WSS was measured during the simulations.ResultsThe WSS was found to have an overall accuracy of 99.5% in detection of four major postures, and 92.5% in the detection of eight minor postures. Prediction of sleep phase using activity measurements was accurate in 97.3% of the simulations. The ability of the system to accurately detect both posture and activity enabled the design of a conceptual layout for a user-friendly tablet application.ConclusionsThe study presents a pervasive wearable sensor platform, which can accurately detect both sleeping posture and activity in non-specialised environments. The extent and accuracy of sleep metrics available advances the current state-of-the-art technology. This has potential diagnostic implications in musculoskeletal pathology and with the addition of aler
Junaid S, Sanghavi S, Anglin C, et al., 2017, Treatment of the Fixation Surface Improves Glenoid Prosthesis Longevity in vitro., Journal of Biomechanics, Vol: 61, Pages: 81-87, ISSN: 0021-9290
Many commercial cemented glenoid components claim superior fixation designs and increased survivability. However, both research and clinical studies have shown conflicting results and it is unclear whether these design variations do improve loosening rates. Part of the difficulty in investigating fixation failure is the inability to directly observe the fixation interface, a problem addressed in this study by using a novel experimental set-up. Cyclic loading-displacement tests were carried out on 60 custom-made glenoid prostheses implanted into a bone substitute. Design parameters investigated included treatment of the fixation surface of the component resulting in different levels of back-surface roughness, flat-back versus curved-back, keel versus peg and more versus less conforming implants. Visually-observed failure and ASTM-recommended rim-displacements were recorded throughout testing to investigate fixation failure and if rim displacement is an appropriate measure of loosening. Roughening the implant back (Ra>3µm) improved resistance to failure (P<0.005) by an order of magnitude with the rough and smooth groups failing at 8712±5584 cycles (mean±SD) and 1080±1197 cycles, respectively. All other design parameters had no statistically significant effect on the number of cycles to failure. All implants failed inferiorly and 95% (57/60) at the implant/cement interface. Rim-displacement correlated with visually observed failure. The most important effect was that of roughening the implant, which strengthened the polyethylene-cement interface. Rim-displacement can be used as an indicator of fixation failure, but the sensitivity was insufficient to capture subtle effects. LEVEL OF EVIDENCE: Basic Science Study, Biomechanical Analysis.
Background: Short stem humeral replacements achieve fixation by anchoring to the metaphyseal trabecular bone. Fixing the implant in high density bone can provide strong fixation and reduce the risk of loosening. However, there is a lack of data mapping the bone density distribution in the proximal humerus. The aim of the study was to investigate the bone density in proximal humerus. Methods: Eight CT scans of healthy cadaveric humeri were used to map bone density distribution in the humeral head. The proximal humeral head was divided into twelve slices parallel to the humeral anatomical neck. Each slice was then divided into four concentric circles. The slices below the anatomical neck, where short stem implants have their fixation features, were further divided into radial sectors. The average bone density for each of these regions was calculated and regions of interest were compared using a repeated measures ANOVA with significance set at p<0.05.Results: Average apparent bone density was found to decrease from proximal to distal regions with the majority of higher bone density proximal to the anatomical neck of the humerus (p<0.05). Below the anatomical neck, bone density increases from central to peripheral regions where cortical bone eventually occupies the space (p<0.05). In distal slices below the anatomical neck, a higher bone density distribution in the medial calcar region was also observed.Conclusion: This study indicates that it is advantageous with respect to implant fixation to preserve some bone above the anatomical neck and epiphyseal plate, and to use the denser bone at the periphery.
Amirthanayagam TD, Amis AA, Reilly P, et al., 2017, Rotator cuff-sparing approaches for glenohumeral joint access: an anatomic feasibility study, Journal of Shoulder and Elbow Surgery, Vol: 26, Pages: 512-520, ISSN: 1058-2746
BackgroundThe deltopectoral approach for total shoulder arthroplasty can result in subscapularis dysfunction. In addition, glenoid wear is more prevalent posteriorly, a region difficult to access with this approach. We propose a posterior approach for access in total shoulder arthroplasty that uses the internervous interval between the infraspinatus and teres minor. This study compares this internervous posterior approach with other rotator cuff–sparing techniques, namely, the subscapularis-splitting and rotator interval approaches.MethodsThe 3 approaches were performed on 12 fresh frozen cadavers. The degree of circumferential access to the glenohumeral joint, the force exerted on the rotator cuff, the proximity of neurovascular structures, and the depth of the incisions were measured, and digital photographs of the approaches in different arm positions were analyzed.ResultsThe posterior approach permits direct linear access to 60% of the humeral and 59% of the glenoid joint circumference compared with 39% and 42% for the subscapularis-splitting approach and 37% and 28% for the rotator interval approach. The mean force of retraction on the rotator cuff was 2.76 (standard deviation [SD], 1.10) N with the posterior approach, 2.72 (SD, 1.22) N with the rotator interval, and 4.75 (SD, 2.56) N with the subscapularis-splitting approach. From the digital photographs and depth measurements, the estimated volumetric access available for instrumentation during surgery was comparable for the 3 approaches.ConclusionThe internervous posterior approach provides greater access to the shoulder joint while minimizing damage to the rotator cuff.
Blackwood C, Dixon J, Reilly P, et al., 2017, Legal and psychological considerations for obtaining informed consent for reverse total shoulder arthroplasty., Shoulder Elbow, Vol: 9, Pages: 15-22, ISSN: 1758-5732
This paper seeks to outline recent legal developments and requirements pertinent to obtaining informed consent. We argue that this is of particular relevance to patients considering a reverse total shoulder arthroplasty, due to the high complication rate associated with this procedure. By examining the cognitive processes involved in decision-making, and other clinician-related factors such as delivery of information, gender bias and conflict of interest, we explore some of the barriers that can undermine the processes of shared decision-making and obtaining genuine informed consent. We argue that these issues highlight the importance for surgeons in understanding the cognitive processes and other influential factors involved in patients' comprehension and decision-making. We recommend, based on strong evidence, that decision aids could prove useful in overcoming such challenges and could provide one way of mitigating the ethical, professional and legal consequences of failing to obtain proper informed consent. They are not widely used in orthopaedics at present, although it would be in the interests of both the surgeon and patient for such measures to be explored.
Darwood A, Secoli R, Bowyer SA, et al., 2016, Intraoperative manufacturing of patient specific instrumentation for shoulder arthroplasty: a novel mechatronic approach, Journal of Medical Robotics Research, Vol: 1, ISSN: 2424-905X
Optimal orthopaedic implant placement is a major contributing factor to the long term success of all common joint arthroplasty procedures. Devicessuch as three-dimensional (3D) printed, bespoke guides and orthopaedic robots are extensively described in the literature and have been shownto enhance prosthesis placement accuracy. These technologies, however, have significant drawbacks, such as logistical and temporal inefficiency,high cost, cumbersome nature and difficult theatre integration. A new technology for the rapid intraoperative production of patient specific instrumentation,which overcomes many of the disadvantages of existing technologies, is presented here. The technology comprises a reusable table sidemachine, bespoke software and a disposable element comprising a region of standard geometry and a body of mouldable material. Anatomicaldata from Computed Tomography (CT) scans of 10 human scapulae was collected and, in each case, the optimal glenoid guidewire position wasdigitally planned and recorded. The achieved accuracy compared to the preoperative bespoke plan was measured in all glenoids, from both a conventionalgroup and a guided group. The technology was successfully able to intraoperatively produce sterile, patient specific guides according toa pre-operative plan in 5 minutes, with no additional manufacturing required prior to surgery. Additionally, the average guide wire placement accuracywas 1.58 mm and 6.82◦ degrees in the manual group, and 0.55 mm and 1.76◦ degrees in the guided group, also demonstrating a statisticallysignificant improvement.
Sukjamsri C, Amis A, Hansen UN, et al., 2015, Digital volume correlation and micro-CT: an in-vitro technique for measuring full-field interface micromotion around polyethylene implants, Journal of Biomechanics, Vol: 48, Pages: 3447-3454, ISSN: 0021-9290
Micromotion around implants is commonly measured using displacement-sensor techniques. Due to the limitations of these techniques, an alternative approach (DVC-μCT) using digital volume correlation (DVC) and micro-CT (μCT) was developed in this study. The validation consisted of evaluating DVC-μCT based micromotion against known micromotions (40, 100 and 150 μm) in a simplified experiment. Subsequently, a more clinically realistic experiment in which a glenoid component was implanted into a porcine scapula was carried out and the DVC-μCT measurements during a single load cycle (duration 20 min due to scanning time) was correlated with the manual tracking of micromotion at 12 discrete points across the implant interface. In this same experiment the full-field DVC-μCT micromotion was compared to the full-field micromotion predicted by a parallel finite element analysis (FEA). It was found that DVC-μCT micromotion matched the known micromotion of the simplified experiment (average/peak error=1.4/1.7 μm, regression line slope=0.999) and correlated with the micromotion at the 12 points tracked manually during the realistic experiment (R2=0.96). The DVC-μCT full-field micromotion matched the pattern of the full-field FEA predicted micromotion. This study showed that the DVC-μCT technique provides sensible estimates of micromotion. The main advantages of this technique are that it does not damage important parts of the specimen to gain access to the bone–implant interface, and it provides a full-field evaluation of micromotion as opposed to the micromotion at just a few discrete points. In conclusion the DVC-μCT technique provides a useful tool for investigations of micromotion around plastic implants.
Shah M, Gburcik V, Reilly P, et al., 2015, LOCAL ORIGINS IMPART CONSERVED BONE TYPE-RELATED DIFFERENCES IN HUMAN OSTEOBLAST BEHAVIOUR, EUROPEAN CELLS & MATERIALS, Vol: 29, Pages: 155-176, ISSN: 1473-2262
Amirthanayagam TD, Emery RJH, 2014, Primum non nocere: risk assessment for new surgical procedures, JOURNAL OF SHOULDER AND ELBOW SURGERY, Vol: 23, Pages: 1417-1418, ISSN: 1058-2746
Amadi HO, Emery RJ, Wallace A, et al., 2014, Specificity of clinical examinations for testing glenohumeral ligament integrity: a computational study, Computer Methods in Biomechanics and Biomedical Engineering, Vol: 17, Pages: 933-943, ISSN: 1025-5842
An accurate diagnosis of glenohumeral joint (GHJ) instability is essential for an effective surgical intervention. There is presently no known comprehensive algorithm of clinical tests for the confirmation of the functional integrity of glenohumeral ligaments (GHLs). A validated computational GHL strain analyser was applied to a set of GHJ kinematics data from the literature to simulate 57 different physiological clinical examination manoeuvres. An algorithm that integrates the GHL pre-straining activities at the toe region of the stress–strain curve was developed for the quantification of ligament loading from prevailing strains. This was used to upgrade the strain analyser and applied to produce a matrix of the various GHL loadings and sensitivities during the manoeuvres. The investigation magnified the likely impact of anatomical variations of GHL attachments as possible causes of misdiagnoses during clinical examinations of GHJ dysfunction. This can serve as an assistive guide to ascertain the functional condition of a specific GHL during symptomatic clinical examinations.
Bayona S, Akhtar K, Gupte C, et al., 2014, Assessing performance in shoulder arthroscopy: The Imperial Global Arthroscopy Rating Scale (IGARS), Journal of Bone and Joint Surgery: American Volume, Vol: 96A, ISSN: 0021-9355
Background: Surgical training is undergoing major changes with reduced resident work hours and an increasing focus on patient safety and surgical aptitude. The aim of this study was to create a valid, reliable method for an assessment of arthroscopic skills that is independent of time and place and is designed for both real and simulated settings. The validity of the scale was tested using a virtual reality shoulder arthroscopy simulator.Methods: The study consisted of two parts. In the first part, an Imperial Global Arthroscopy Rating Scale for assessing technical performance was developed using a Delphi method. Application of this scale required installing a dual-camera system to synchronously record the simulator screen and body movements of trainees to allow an assessment that is independent of time and place. The scale includes aspects such as efficient portal positioning, angles of instrument insertion, proficiency in handling the arthroscope and adequately manipulating the camera, and triangulation skills. In the second part of the study, a validation study was conducted. Two experienced arthroscopic surgeons, blinded to the identities and experience of the participants, each assessed forty-nine subjects performing three different tests using the Imperial Global Arthroscopy Rating Scale. Results were analyzed using two-way analysis of variance with measures of absolute agreement. The intraclass correlation coefficient was calculated for each test to assess inter-rater reliability.Results: The scale demonstrated high internal consistency (Cronbach alpha, 0.918). The intraclass correlation coefficient demonstrated high agreement between the assessors: 0.91 (p < 0.001). Construct validity was evaluated using Kruskal-Wallis one-way analysis of variance (chi-square test, 29.826; p < 0.001), demonstrating that the Imperial Global Arthroscopy Rating Scale distinguishes significantly between subjects with different levels of experience utilizing a virtual reali
Gregory T, Hansen U, Khanna M, et al., 2014, A CT scan protocol for the detection of radiographic loosening of the glenoid component after total shoulder arthroplasty, Acta Orthopaedica, Vol: 85, Pages: 91-96, ISSN: 0001-6470
Background and purpose It is difficult to evaluate glenoid component periprosthetic radiolucencies in total shoulder arthroplasties (TSAs) using plain radiographs. This study was performed to evaluate whether computed tomography (CT) using a specific patient position in the CT scanner provides a better method for assessing radiolucencies in TSA.Methods Following TSA, 11 patients were CT scanned in a lateral decubitus position with maximum forward flexion, which aligns the glenoid orientation with the axis of the CT scanner. Follow-up CT scanning is part of our routine patient care. Glenoid component periprosthetic lucency was assessed according to the Molé score and it was compared to routine plain radiographs by 5 observers.Results The protocol almost completely eliminated metal artifacts in the CT images and allowed accurate assessment of periprosthetic lucency of the glenoid fixation. Positioning of the patient within the CT scanner as described was possible for all 11 patients. A radiolucent line was identified in 54 of the 55 observed CT scans and osteolysis was identified in 25 observations. The average radiolucent line Molé score was 3.4 (SD 2.7) points with plain radiographs and 9.5 (SD 0.8) points with CT scans(p = 0.001). The mean intra-observer variance was lower in the CT scan group than in the plain radiograph group (p = 0.001).Interpretation The CT scan protocol we used is of clinical value in routine assessment of glenoid periprosthetic lucency after TSA. The technique improves the ability to detect and monitor radiolucent lines and, therefore, possibly implant loosening also.
Gregory TM, Sankey A, Augereau B, et al., 2013, Accuracy of Glenoid Component Placement in Total Shoulder Arthroplasty and Its Effect on Clinical and Radiological Outcome in a Retrospective, Longitudinal, Monocentric Open Study, PLOS ONE, Vol: 8, ISSN: 1932-6203
The incidence of proximal humeral trauma continues to rise. Treatment of complex proximal humeral trauma remains challenging and controversial. So far, classification of humeral fractures is an unsatisfactory process. In this paper we explore how we make decisions in this unique setting and present early results of using Markov Chain Monte Carlo modeling to assess concepts in surgical pattern recognition.
Gregory T, Hansen U, Emery R, et al., 2012, Total shoulder arthroplasty does not correct the orientation of the eroded glenoid, ACTA ORTHOPAEDICA, Vol: 83, Pages: 529-535, ISSN: 1745-3674
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