Pre-operative planning for reverse shoulder arthroplasty in low-resource centres: A modified Delphi study in South Africa.

BACKGROUND: Pre-operative planning for reverse shoulder arthroplasty (RSA) poses challenges, particularly when dealing with glenoid bone loss. This modified Delphi study aimed to assess expert consensus on RSA planning processes and rationale, specifically targeting low-resourced institutions. Our objective was to offer pre-operative decision-making algorithms tailored for surgeons practising in resource-constrained hospitals with limited access to computed tomography (CT) scans. METHODS: A working group generated statements on pre-operative imaging and glenoid of glenoid morphology and intra-operative decision-making. The study was conducted in three stages, with virtual consensus meetings in between. Stages 2 and 3 consisted only of closed questions/statements. The statements with over 70% were considered consensus achieved and those with less than 10% were considered disagreement consensus achieved. RESULTS: Twelve shoulder surgeons participated, with 67% having over five years of experience in shoulder arthroplasty. In the absence of glenoid bone loss, the sole use of plain radiographs for pre-operative planning reached consensus and is recommended by these groups, while 100% advise using CT scans when bone loss is present. Most surgeons (70%) recommend using patient-specific instrumentation (PSI) in cases of structural bone loss. Most of the statements on intra-operative decision-making related to component placement and enhancing stability failed to reach consensus. CONCLUSION: While consensus was achieved on most aspects of pre-operative imaging and planning, technical aspects of surgery lacked consensus. Planning for patients with structural glenoid bone loss necessitates CT scans and planning tools.

Moment arms of the coracobrachialis and short head of biceps following a Latarjet procedure: a modeling study.

BACKGROUND: The Latarjet procedure transfers the coracoid process to the anterior glenoid. This prevents recurrent anterior humeral dislocation but alters the origins of the coracobrachialis (CBR) and short head of the biceps (SHB). The impact of this alteration on the moment arms of these muscles has not been examined. METHODS: The Newcastle Shoulder Model was updated with 15 healthy cadaveric bone models to create customized shoulder models. The CBR and SHB muscles were attached to the anterior glenoid via an elliptical wrapping object. Muscle moment arms were calculated for abduction, forward flexion, scapular plane elevation, and internal rotation with 20° and 90° of abduction. Statistical comparison of moment arms between native and Latarjet shoulders was performed using spm1D. RESULTS: By transferring the origins of the CBR and SHB to the anterior glenoid, both muscles had extension moment arms during glenohumeral elevation in the coronal, sagittal, and scapular planes. Their average moment arms during abduction (-30.4 ± 3.2 mm for CBR and -29.8 ± 3.0 mm for SHB) and forward flexion (-26.0 ± 3.1 mm for CBR and -26.2 ± 3.2 mm for SHB) suggested that their role after the Latarjet procedure changed compared with their role in the native shoulder (P < .001). At higher abduction levels, both the muscles had higher internal rotation moment arms compared with the native shoulder. CONCLUSION: The Latarjet procedure affected the moment arms of the CBR and SHB. Both muscles had increased extension and internal rotation moment arms at higher degrees of elevation compared with the native shoulders. This finding suggests that these muscles act as dynamic stabilizers after the Latarjet procedure.

A narrative review of treatment strategies for major glenoid defects during primary reverse shoulder arthroplasty, with a focus on the use of structural bone graft.

Structural glenoid defects are common during primary reverse shoulder arthroplasty (RSA) and are often associated with poor outcomes. The lack of pre-operative imaging protocols for determining the depth and degree of glenoid wear hinders our ability to accurately plan and correct these defects. Although bone grafting has been reported to be effective in reducing glenoid wear during RSA, there is limited information on when to utilise it and how to prepare the graft. We conducted this review to assess the evidence for the management of glenoid defects, with an emphasis on bone grafts to treat structural glenoid bone loss in primary RSA patients.

Characterizing moment arms of the coracobrachialis and short head of biceps in native shoulders and after reverse total shoulder arthroplasty during elevation and rotation: a modeling study.

BACKGROUND: Reverse total shoulder arthroplasty (RTSA) alters the line of action of muscles around the glenohumeral joint. The effects of these changes have been well characterized for the deltoid, but there is limited information regarding the biomechanical changes to the coracobrachialis (CBR) and short head of biceps (SHB). In this biomechanical study, we investigated the changes to the moment arms of the CBR and SHB due to RTSA using a computational model of the shoulder. METHODS: The Newcastle Shoulder Model, a pre-validated upper-extremity musculoskeletal model, was used for this study. The Newcastle Shoulder Model was modified with bone geometries obtained from 3-dimensional reconstructions of 15 nondiseased shoulders, constituting the native shoulder group. The Delta XTEND prosthesis, with a glenosphere diameter of 38 mm and polyethylene thickness of 6 mm, was virtually implanted in all the models, creating the RTSA group. Moment arms were measured using the tendon excursion method, and muscle length was calculated as the distance between the muscle's origin and insertion points. These values were measured during 0°-150° of abduction, forward flexion, scapular-plane elevation, and -90° to 60° of external rotation-internal rotation with the arm at 20° and 90° of abduction. Statistical comparisons between the native and RTSA groups were analyzed using 1-dimensional statistical parametric mapping (spm1D). RESULTS: Forward flexion moment arms showed the greatest increase between the RTSA group (CBR, 25.3 ± 4.7 mm; SHB, 24.7 ± 4.5 mm) and native group (CBR, 9.6 ± 5.2 mm; SHB, 10.2 ± 5.2 mm). The CBR and SHB were longer in the RTSA group by maximum values of 15% and 7%, respectively. Both muscles had larger abduction moment arms in the RTSA group (CBR, 20.9 ± 4.3 mm; SHB, 21.9 ± 4.3 mm) compared with the native group (CBR, 19.6 ± 6.6 mm; SHB, 20.0 ± 5.7 mm). Abduction moment arms occurred at lower abduction angles in the RTSA group (CBR, 50°; SHB, 45°) than in the native group (CBR, 90°; SHB, 85°). In the RTSA group, both muscles had elevation moment arms until 25° of scapular-plane elevation motion, whereas in the native group, the muscles only had depression moment arms. Both muscles had small rotational moment arms that were significantly different between RTSA and native shoulders during different ranges of motion. CONCLUSION: Significant increases in elevation moment arms for the CBR and SHB were observed in RTSA shoulders; these increases were most pronounced during abduction and forward elevation motions. RTSA also increased the lengths of these muscles.

Development of a framework to assess the biomechanical impact of reverse shoulder arthroplasty placement modifications.

Reverse shoulder arthroplasty biomechanics can be improved by modifying the placement of prosthesis. Biomechanical studies have quantified the impact of placement modifications on the mobility and stability of the reverse shoulder. While these studies have provided detailed insights, direct comparisons between their finding are obfuscated by their use of differing methodologies. The aim of our study was to develop an assessment framework which used musculoskeletal simulations to consistently evaluate the biomechanics of various placement modifications. We conducted musculoskeletal simulations of humeral elevations and rotations using 15 reverse shoulder models. For each model, these simulations were conducted for a reference configuration of the prosthesis, established using surgical guidelines, and 34 modified configurations, which were based on commonplace adaptations to the placement of the glenosphere and humeral tray. The effect of each modified configuration on deltoid elongation, deltoid moment arm (DMA), joint stability, and impingement-free range of motion (IFROM) was determined relative to the reference configuration. We found that 16 of the 34 modified placements had an overall beneficial impact on reverse shoulder biomechanics. Within this subset, we identified two biomechanical trade-offs. First, there is an antagonistic relationship between IFROM and both the DMA and joint stability. Second, functional requirements differ between humeral elevations and rotations. Furthermore, we found that posteromedial translation of the humeral tray had the most beneficial impact on joint stability and inferior translation of the glenosphere had the most beneficial impact on IFROM and DMA.

Identification of recurring scapular fracture patterns using 3-dimensional computerized fracture mapping.

BACKGROUND: Scapular fracture fixation and implant selection are guided by the fracture pattern and classification, which requires accurate understanding and interpretation of the fracture lines. Three-dimensional (3D) computed tomography (CT)-based fracture pattern analysis enhances a more accurate understanding of the scapular fracture patterns. The purpose of this study was to create scapular fracture maps and identify the frequent fracture patterns using 3D reconstructed CT images. METHOD: Seventy patients treated for scapular fractures, in a single hospital, were considered for this study. Their CT images were reconstructed into 3D models and the fracture fragments were virtually reduced. The reduced 3D models were first aligned on a 3D template and 2D images were captured on the anterior, posterior, and lateral views. Then each fracture image was aligned on a corresponding 2D template and the fracture lines were transferred to the template. The 3 separate views were used to accurately capture the propagation and exit of the fractures through the scapular anatomy. These fracture lines were compiled and heat maps were generated to identify the frequent fracture zones of the scapula. RESULT: The observed scapular fractures propagated through multiple regions of the bone. Overall, the 3 most common exit zones in the scapula were the lateral (69%), medial (67%), and superior borders (60%). More specifically, the superior lateral border, medial base of the scapula spine, spinoglenoid notch, and mid-superior border were the most frequent zones of fracture in the scapular body. Simple intra-articular fractures (transverse or oblique type) were the most common (92%) fracture type in the glenoid region. CONCLUSION: Scapular fractures reveal repeatable patterns. The zones of recurrent fracture patterns can be identified from fracture and heat maps. Graphical plots of fracture and heat maps may assist surgical planning and implant design optimization.

Quantitative fit analysis of acromion fracture plating systems using three-dimensional reconstructed scapula fractures - A multi-observer study.

INTRODUCTION: Surgical treatment of displaced acromial and scapula spine fractures may be challenging due to the bony anatomy and variable fracture patterns. This difficulty is accentuated by the limitations of the available scapular plates for fracture fixation. This study compares the quantitative fitting of anatomic scapular plates and clavicle plates, using three-dimensional (3D) printed fractured scapulae. METHODS: Fourteen scapulae with acromion and spine fractures were used for this study. Computerized tomographic (CT) scans of the fractured scapulae were obtained from the Philips picture archiving and communication system (PACS) database of patients admitted to a tertiary teaching hospital in Cape Town, South Africa between 2012 and 2016. The reconstructed scapulae were 3D printed and the anatomical acromion and clavicle plates were templated about the fracture regions. The fit assessment was performed by five observers who classified the plates as no-fit, intermediate fit, and anatomical fit according to the surgical guidelines. RESULTS: The 6-hole anterior clavicle plate performed better than any of the scapular plates as they were able to fit 45.7% of the fractured acromion, including the spine. Among the pre-contoured anatomical scapula plates, both the short and the long acromion plates could fit only 27.3% of the fractured acromion. The intraclass correlation coefficient was 0.965 suggesting excellent consensus among the five observers. CONCLUSION: Clavicle plates were found to be better suited to fit around a scapula fracture in its acromion and spine region.

A Randomized Controlled Trial of Eccentric Versus Concentric Cycling for Anterior Cruciate Ligament Reconstruction Rehabilitation.

BACKGROUND: Persistent strength and biomechanical deviations remain after anterior cruciate ligament reconstruction (ACLR). Eccentric training may reduce these and associated reinjury or osteoarthritis risks. HYPOTHESIS: For male patients who have undergone ACLR, eccentric training is more effective than concentric training at improving knee flexion angle and other biomechanical deviations, as well as strength and patient-reported outcomes, using a matched perceived exertion dose. STUDY DESIGN: Randomized controlled trial; Level of evidence, 1. METHODS: A total of 26 men, 10-16 weeks after hamstring tendon graft ACLR, were randomized to an eccentric training group or a concentric control group. Both groups trained 3 times a week for 8 weeks using the same isokinetic cycle ergometer in a matched studio environment. Exercise dose was matched in training frequency, time, progression, and intensity using a target rating of perceived exertion. Baseline and follow-up testing included questionnaires, dynamometer strength testing, and walk/run gait analysis. RESULTS: Eccentric training increased knee (+2.1°; P = .022) and hip (+2.1°; P = .010) flexion angles more than concentric training but not more than the minimal clinically important difference of 3°. Very large asymmetries in baseline knee abduction moment (walk, -0.10 N·m/kg/m; run, -0.54 N·m/kg/m) had not changed in either group by follow-up. Knee valgus angle effects were mixed. Tibial rotation angle increased in both groups, but concentric training was more effective at promoting symmetry (P < .001). Both groups had similar increases in affected limb quadriceps strength and knee flexion moments during walk/run gait (by 20% to 33%). Hamstring strength increased in the eccentric group (+15.4%) but not the concentric group. Eccentric group limb forces were 33% to 70% higher than those of the concentric group, with a lower heart rate. Both groups had low pain scores throughout. CONCLUSION: For rehabilitation after ACLR, progressive eccentric cycle training was not more clinically effective than concentric training at a matched perceived intensity dose in male patients. This can guide exercise prescription for reducing gait and strength deviations of these patients. REGISTRATION: PACTR201602001449365 (Pan African Clinical Trials Registry), NHREC 4344 (South African).

Influence of Different Connecting Rod Configurations on the Stability of the Ilizarov/TSF Frame: A Biomechanical Study.

AIM: The Ilizarov external fixator (IEF) is frequently used in trauma and elective orthopaedics. Many of its biomechanical variables (ring size, wire diameter, wire number, half pins vs wires, etc.) and their influence on stability and stiffness have been investigated. There is, however, a paucity in the literature regarding the influence of the connecting rod numbers and configurations between the rings on IEF stability. The primary aim of this biomechanical study was to compare the stability between four- and three-rod IEF configurations. Secondarily to assess the difference in stability between symmetrical and asymmetrical spacing of the IEF rods. MATERIALS AND METHODS: A custom jig was designed to facilitate mounting of a basic two-ring IEF in a hydraulic press. Controlled centre and off-centre (thus simulated bending) axial loading was then applied across the frame. The configurations were loaded up to 4,000 N. The frame deformation was plotted and the data were then analysed and interpreted. RESULTS: Negligible differences were observed between different four- and three-rod configurations as long as the applied force at the loading point (LP) was within the area of support (AOS) created by the rods. The different four-rod constructs were always more stable than the three-rod constructs during bending. CONCLUSION: There is comparable stiffness between a four-rod and a three-rod IEF construct as long as the LP is within the AOS created by the rods. A four-rod IEF is stiffer than a three-rod IEF in bending. CLINICAL SIGNIFICANCE: This study will possibly change some paradigms regarding the planning and application of IEFs by Orthopaedics Traumatologists and Reconstruction Surgeons. HOW TO CITE THIS ARTICLE: Thiart G, Herbert C, Sivarasu S, et al. Influence of Different Connecting Rod Configurations on the Stability of the Ilizarov/TSF Frame: A Biomechanical Study. Strategies Trauma Limb Reconstr 2020;15(1):23-27.

An interpopulation comparison of 3-dimensional morphometric measurements of the proximal humerus.

BACKGROUND: Precise anatomic reconstruction of the proximal humerus is essential to a favorable outcome of total shoulder arthroplasty. Because of the wide variation in the geometric features of the proximal humerus, prosthetic designs incorporating these disparities are being developed. METHODS: The aim of this study is to use data obtained from cadavers and computed tomographic scans to investigate the 3-dimensional morphometric parameters of the proximal humerus of South African and Swiss samples and make an interpopulation comparison. In addition, the study combines the interarticular variations between populations with the differences in sex and shoulder sides. With the aid of medical imaging techniques and engineering design tools, various geometric features were measured. RESULTS: The results obtained from these analyses revealed several differences in sex and shoulder sides. On average, the Swiss were larger in most of the measured parameters than the South Africans. The male shoulders of Swiss and South Africans were observed to significantly vary in 4 of the parameters measured. The South African male and female right shoulders varied considerably in one-fourth of the measured shoulder variables. Generally, for both populations, the left and right shoulders of the same individuals were not different in all the measured variables irrespective of sex. CONCLUSION: The knowledge acquired in this study is expected to assist in the development of a population-specific shoulder prosthetic design and surgical planning procedures.

Diagnostics as the Key to Advances in Global Health: Proposed Methods for Making Reliable Diagnostics Widely Available.

This paper proposes a structure and method for the development of an AI diagnostic system as a highly leveraged step toward improvements in delivery of healthcare in underserved regions. First, the paper provides a high-level, general review of the current efforts to provide healthcare services in underserved areas and the many efforts being made to impact health outcomes by various international, governmental, and NGO entities. We also very briefly review university programs and research institutions that have specific technical and institutional assets with significant potential to carry out research or to partially implement such a plan. Our review uses weighted values in a decision-system that takes in a variety of assets we consider fundamental to successful engagement in delivery of new, innovative, technology-enabled healthcare systems for under-resourced settings. We then review nine factors that hinder the advancement in healthcare in under-resourced settings, some of which are well described in current literature and some that may bring new perspectives. The paper then attempts to review how a proposed system can manage to operate successfully within the context of the nine named hindrance factors. The primary focus of the paper is in the description of a system which can increase the availability of diagnostics through technology-enabled systems. Such a system would impact the outcomes of persons in underserved regions. The paper then describes why making diagnostics available is a critical priority among efforts for improvements in global health.

Effect of humeral tray placement on impingement-free range of motion and muscle moment arms in reverse shoulder arthroplasty.

BACKGROUND: It has been suggested that onlay humeral tray placement in reverse shoulder arthroplasty can affect impingement and muscle functionality. This study investigates biomechanical changes to the reversed shoulder using a variety of tray positional configurations. METHODS: The reconstructed scapula and humerus from 12 CT scans were used to customise a 3D biomechanical model of the shoulder. Each model underwent virtual RSA surgery using a commercially available prosthesis that was reconstructed from an explant. 17 tray positions were tested: the default location with no offset and 16 offset locations (2.5 and 5 mm radial offsets over 45° circumferential intervals). Impingement and muscle moment arms were measured during three standardised activities, and impingement was measured during an activity of daily living. FINDINGS: Offset direction was found to have an effect (P < 0.05) on extra-articular impingement and muscle moment arms for all activities; whereas, offset distance did not (P > 0.05). Overall, impingement-free range of motion was maximised using a posterolateral tray offset and muscle moment arms were maximised using a medial tray offset. An antagonistic relationship between changes to impingement and muscle moment arms due to tray placement was identified and, consequently, the simultaneous maximisation of both outcome measures was not possible. INTERPRETATION: The functional outcomes of reverse shoulder arthroplasty can be improved by altering onlay humeral tray placement. Due to the antagonistic relationship between the impingement and muscle moment arms, placement of the tray should be guided by patient-specific characteristics.

Open source modular ptosis crutch for the treatment of myasthenia gravis.

INTRODUCTION: Pharmacologic treatment of Myasthenia Gravis presents challenges due to poor tolerability in some patients. Conventional ptosis crutches have limitations such as interference with blinking which causes ocular surface drying, and frequent irritation of the eyes. To address this problem, a modular and adjustable ptosis crutch for elevating the upper eyelid in Myasthenia Gravis patients has been proposed as a non-surgical and low-cost solution. AREAS COVERED: This paper reviews the literature on the challenges in the treatment of Myasthenia Gravis globally and focuses on a modular and adjustable ptosis crutch that has been developed by the Medical Device Laboratory at the University of Cape Town. EXPERT COMMENTARY: The new medical device has potential as a simple, effective and unobtrusive solution to elevate the drooping upper eyelid(s) above the visual axis without the need for medication and surgery. Access to the technology is provided through an open source platform which makes it available globally. Open access provides opportunities for further open innovation to address the current limitations of the device, ultimately for the benefit not only of people suffering from Myasthenia Gravis but also of those with ptosis from other aetiologies.

Anatomic variations in glenohumeral joint: an interpopulation study.

BACKGROUND: This study focused on the unique aspect of investigating shoulder morphometric differences between 2 distinct populations. METHODS: We used 90 computed tomography images of cadaveric shoulders for this study; 45 scans belonged to the South African (SA) cohort (49.74 ± 15.4 years) and the rest were Swiss (CH; 53.8 ± 21 years). The articulating surfaces of the glenohumeral joint were extracted, and their morphometric features, such as head circular diameter, glenoid and humeral head radius of curvature, head height, and humeral height, were measured. RESULTS: The mean interpopulation difference in the circular diameter of the humerus was 2.0 mm (P = .017) and 1.86 mm (P > .05) in the anterior-posterior and superior-inferior directions, respectively. The difference in the radius of curvature between the populations was 1.17 mm (P = .037). The SA shoulders were found to be longer than the CH shoulders by 8.4 mm (P > .05). There was no significant difference in the glenoid radius of curvature. The SA shoulders had higher glenohumeral mismatch (P = .005) and lower conformity index (P = .001) in comparison to the CH shoulders. CONCLUSION: This study presents anatomic differences between African and European glenohumeral articulating surfaces. The results suggest that the glenohumeral geometry is both gender and population specific, and future joint replacements may be designed to address these differences.

Assessment of 3D morphological characteristics of the shoulder bones using statistical shape modeling: Prospective application to handedness.

In this study we have described the use of statistical shape modeling (SSM) technique in evaluating the morphological variation of shoulder bones from a South African population. The anatomical landmark selections were carried out, followed by the registration of the meshes which were validated before establishing the dense correspondence. The SSMs were built and average shape comparison from each side for each bone were made in order to evaluate handedness. In general, there was no error found around the gleno-humeral region which may suggest that the usage of contralateral healthy shoulder could serve as an informed decision making tool for surgery and prosthesis design.

Subject-specific shoulder muscle attachment region prediction using statistical shape models: A validity study.

Subject-specific musculoskeletal models can predict accurate joint and muscle biomechanics thereby helping clinicians and surgeons. Current modeling strategies do not incorporate accurate subject-specific muscle parameters. This study reports a statistical shape model (SSM) based method to predict subject-specific muscle attachment regions on shoulder bones and illustrates the concurrent validity of the predictions. Augmented SSMs of scapula and humerus bones were built using bone meshes and five muscle attachment (origin/insertion) regions which play important role in the shoulder motion and function. Muscle attachments included Subscapularis, Supraspinatus, Infraspinatus, Teres Major and Teres Minor on both the bones. The regions were represented by subset of vertices on the bone meshes and were tracked using vertex identifiers. Subject-specific muscle attachment regions were predicted using external set of bones not used in building the SSMs. Validity of predictions was determined by visual inspection and also by using four similarity measures between predicted and manually segmented regions. Excellent concurrent validity was found indicating the higher accuracy of predictions. This method can be effectively employed in modeling pipelines or in automatic segmentation of medical images. Further validations are warranted on all the muscles of the shoulder complex.

Kinematic and kinetic gait deviations in males long after anterior cruciate ligament reconstruction.

BACKGROUND: Biomechanical deviations long (approx. 5years) after anterior cruciate ligament reconstruction have not been quantified in males, despite their distinct risk profile as compared to females. These deviations can indicate altered joint loading during chronic, repetitive motions. METHODS: Cross-sectional study, comparing kinematic and kinetic variables between 15 male anterior cruciate ligament reconstructed patients and 15 healthy controls. During walking and running gait, measurements were taken of impact dynamics, knee and hip sagittal plane angles and moments, and knee varus angles and adduction moments. FINDINGS: Comparing affected limbs to control limbs, significantly lower maximum (P=0.001) and initial (P=0.003) loading rates were found during running, but not in walking. Hip angles were lower for affected limbs of patients compared to the control group (P=0.039) in walking, but not during running. Between-limb comparisons showed important differences in symmetry of the affected patients. Maximum force during running was higher in the unaffected limb (P=0.015), which was linked with a higher loading rate (P=0.008). Knee flexion angle was reduced by 2° on average for the affected limb during running (P=0.010), and both walking and running knee and hip moments showed differences. Knee varus angle showed a 1° difference during walking (P<0.001), but not during running. Knee adduction moment was significantly lower (more valgus) during both walking and running. INTERPRETATION: Male anterior cruciate ligament reconstructed patients demonstrate persistent, clinically important gait asymmetries and differences from healthy controls long after surgery in kinematics, kinetics, and impact biomechanics.

Finite element model-based evaluation of tissue stress variations to fabricate corrective orthosis in feet with neutral subtalar joint.

BACKGROUND: The subtalar joint position during static stance is a crucial determinant of the peak plantar pressures and forms ideal reference point for any intervention in foot-related problems for leprosy-affected patients. OBJECTIVES: The study pursued the hypothesis through a three-dimensional model that stress will be minimal in the distal joints of the foot when the subtalar joint is in neutral static stance position. STUDY DESIGN: Finite element model. METHODS: The computed tomography images of the feet for five patients suffering from Hansen's disease having no muscle weakness and joint restriction were acquired. The gray intensities corresponding to the bones of the foot from the computed tomography images were three-dimensionally reconstructed. The three-dimensional model of the human foot, incorporating the realistic geometry, and the material properties of the hard tissues were then analyzed using a finite element solver for the stress distribution on bones of the foot. RESULTS: The results demonstrate that the position of the calcaneum in the static stance position does contribute to the varying stress in the foot. CONCLUSION: The stresses in the bones of the foot are minimal while the subtalar is in neutral position; this position will be suitable for foot orthotic fabrication. Clinical relevance The clinicians, therapists, and podiatrists having less engineering skills can quickly assess the patient and get optimal results on the stress associated with the joints of the foot.

Femoral neck anteversion measurement using linear slot scanning radiography.

Measurements between anatomical landmarks on radiographs are useful for diagnosis and treatment planning in the orthopedic field. Direct measurement on single radiographic images, however, does not truly reflect spatial relationships, as depth information is lost. We used stereo images from a slot scanning X-ray machine to estimate coordinates of three-dimensional (3D) bony landmarks for femoral neck anteversion (FNA) measurement. A set of 7 landmarks consisting of the centre of the femoral head; the centre of the base of the femoral neck; the medial and lateral condyles; the medial and lateral posterior condyles; and finally the centre of the knee; were found to be identifiable and suitable for radiographic measurement. The reconstructed 3D coordinates were then used to define the 3D geometry of the anatomical axes required to estimate FNA. Stereophotogrammetric measurements on a sample of 30 dry right adult femurs were compared to reference values obtained using the Kingsley Olmstead method applied to photographic images. A strong positive correlation (0.998) was found and the mean ± standard deviation of the stereophotogrammetric approach (13.08 ± 6.87)° was comparable to that of the Kingsley Olmstead method (13.14 ± 6.88)°. Intra- and inter-observer reliability were high, with the lower bound of the 95% confidence interval above 0.98 for the intra-class correlation coefficient. The results merit further validation against three dimensional imaging technology such as computed tomography, to confirm stereophotogrammetry as a suitable alternative for FNA measurement.

Design of mechanical interface to re-distribute excess pressure to prevent the formation of decubitus ulcers in bed ridden patients.

Pressure ulcers are the major problem in the stroke management and rehabilitation. Prevention of pressure ulcer is of keen interest and is achieved by frequently changing the position of patient on the mattress. However, the care needs to be intensive to address this issue; else it would lead to pressure ulcer or bed sores formation. Skin surface over the bony prominences provide comparatively more pressure than the other regions. Therefore they are called as pressure vulnerable regions. Skin over these regions is more susceptible for formation of ulcers. An engineering approach is needed to shift the accumulating pressure from the pressure vulnerable regions. Although pressure sensed in these region would be more than that of which sensed in other regions, shifting protocol has to be designed to channelize or to grade the pressure shift in order to avoid any injuries to the non pressure vulnerable region. This paper aims at devising one such protocol using MATLab and thereby designing the layout of mattress using Pro/Engineer: the number of partitions needed to cover the entire surface of the skin that is in contact with the mattress.