Fully automated patellofemoral MRI segmentation using holistically nested networks: Implications for evaluating patellofemoral osteoarthritis, pain, injury, pathology, and adolescent development.

PURPOSE: Our clinical understanding of the relationship between 3D bone morphology and knee osteoarthritis, as well as our ability to investigate potential causative factors of osteoarthritis, has been hampered by the time-intensive nature of manually segmenting bone from MR images. Thus, we aim to develop and validate a fully automated deep learning framework for segmenting the patella and distal femur cortex, in both adults and actively growing adolescents. METHODS: Data from 93 subjects, obtained from on institutional review board-approved protocol, formed the study database. 3D sagittal gradient recalled echo and gradient recalled echo with fat saturation images and manual models of the outer cortex were available for 86 femurs and 90 patellae. A deep-learning-based 2D holistically nested network (HNN) architecture was developed to automatically segment the patella and distal femur using both single (sagittal, uniplanar) and 3 cardinal plane (triplanar) methodologies. Errors in the surface-to-surface distances and the Dice coefficient were the primary measures used to quantitatively evaluate segmentation accuracy using a 9-fold cross-validation. RESULTS: Average absolute errors for segmenting both the patella and femur were 0.33 mm. The Dice coefficients were 97% and 94% for the femur and patella. The uniplanar, relative to the triplanar, methodology produced slightly superior segmentation. Neither the presence of active growth plates nor pathology influenced segmentation accuracy. CONCLUSION: The proposed HNN with multi-feature architecture provides a fully automatic technique capable of delineating the often indistinct interfaces between the bone and other joint structures with an accuracy better than nearly all other techniques presented previously, even when active growth plates are present.

Increased Patellar Volume/Width and Decreased Femoral Trochlear Width Are Associated With Adolescent Patellofemoral Pain.

BACKGROUND: Patellofemoral pain is one of the most common forms of knee arthralgia in adolescent females. Unlike in adults, in whom the etiology of patellofemoral pain is considered to be multifactorial (eg, altered bone shape and musculoskeletal dynamics), the etiology of adolescent patellofemoral pain has been historically attributed to overuse. Although it is highly plausible that adolescent patellofemoral pain results from excessive maltracking, as suggested by recent research, an increase in patellar, relative to femoral, size could also contribute to patellofemoral pain through altered cartilage stresses/strains, resulting in overloading of the subchondral bone. Because the role of bone morphology in the genesis of patellofemoral pain in adolescent females remains largely unknown, research is needed in this area to improve our understanding of patellofemoral pain and advance diagnosis/treatment. QUESTIONS/PURPOSES: (1) Are patellar volume and width increased, and femoral trochlear width decreased, in female adolescents with patellofemoral pain compared with asymptomatic females? (2) Are measures of patellofemoral size correlated with patellofemoral tracking? METHODS: Twenty adolescent females with patellofemoral pain (age, 13.7 ± 1.3 years) and 20 asymptomatic female control participants (age, 13.6 ± 1.3 years) were enrolled in this case-control institutional review board-approved study. This study focused on a strict definition of patellofemoral pain, peripatellar pain in the absence of other structural pathologic conditions (eg, tendinitis, ligament injury, Osgood-Schlatter disease) or a history of dislocations/trauma. Control participants with no history of patellofemoral pain or other lower extremity pathology were matched for age (within 6 months) and body mass index (within 5 kg/m). Participants self-referred and were recruited through clinicaltrails.gov, printed advertisements, and word of mouth. Three-dimensional (3-D), static, T1-weighted, gradient recalled echo MR images were acquired, from which 3-D patellofemoral models were created. Patellar volume and width, patellar-to-femoral volume and width ratios, and femoral trochlear width were compared across cohorts. In addition, 3-D patellofemoral tracking was quantified from dynamic MR images captured during cyclical flexion-extension volitional movements of the lower extremity. The size measures and ratios were correlated to patellofemoral tracking. RESULTS: Compared with control participants, the cohort with patellofemoral pain had greater patellar volume (13,792 ± 2256 versus 11,930 ± 1902 mm; 95% confidence interval [CI], 1336 mm; p = 0.004; d = 0.89) and width (38.4 ± 3.0 versus 36.5 ± 2.7 mm; 95% CI, 1.8 mm; p = 0.021; d = 0.67). The femoral trochlear width was smaller (32.0 ± 1.8 versus 32.9 ± 1.8 mm; p = 0.043, d = 0.54). The patellar-to-femoral volume ratio and the patellar-to-trochlear width ratio were greater in adolescents with patellofemoral pain (0.15 ± 0.02 versus 0.13 ± 0.01, p = 0.006, d = 0.83 and 1.20 ± 0.09 versus 1.11 ± 0.09, p = 0.001, d = 1.02). No correlations were found between patellar size and patellofemoral tracking (r < 0.375, p > 0.103). CONCLUSIONS: In adolescent females with patellofemoral pain, the increased patellar volume/width and patellar-to-trochlear width ratio, along with the decreased femoral trochlear width, may initiate a pathway to pain through improper engagement of the patella within the femoral trochlea. Specifically, the mean differences between cohorts in patellar and femoral trochlear width (1.9 mm and 0.9 mm) are 58% and 37% of the mean patellar and femoral cartilage thickness in females, respectively, as reported in the literature. Further studies are needed to fully elucidate the mechanism of pain. LEVEL OF EVIDENCE: Level III, prognostic study.

The clinical characteristics of Kleine-Levin syndrome according to ethnicity and geographic location.

PURPOSE: Kleine-Levin syndrome (KLS) is a rare, relapsing-remitting, debilitating sleep disorder. Examining KLS characteristics in different ethnic populations may help elucidate the genetic basis of the disorder. No studies have examined KLS in Arabs. Therefore, we compared the clinical characteristics of Saudi Arabian KLS patients to those in other published cohorts to determine whether Arab patients have a distinct phenotype. METHODS: This study included all patients who were diagnosed with KLS at our center between June 2003 and July 2016 (P = 12; Six familial cases). All participants completed the Stanford KLS questionnaire. Anxiety and depression were assessed using the Hospital Anxiety and Depression Scale; eating attitudes were assessed with the Eating Attitudes Test-26. We compared the clinical characteristics of our patients to those in other published cohorts. RESULTS: Saudi Arabian patients with KLS had similar features to those in patients from different countries and ethnic backgrounds, with only minor differences in sleep duration during disease episodes (2-3 h shorter). However, between episodes, Saudi Arabian KLS patients reported worse sleep, greater daytime sleepiness and higher levels of baseline depression, which may be related to KLS or to local cultural practices. Ankylosing spondylitis was present in five of the six familial patients. CONCLUSION: Saudi Arabian patients with KLS exhibited similar clinical characteristics during episodes compared to patients with KLS of different ethnicities. However, a new and interesting finding is that KLS patients may have inter-episode behavioral and pathophysiological changes, which may suggest that KLS is not necessarily a static disorder.

Cardiorespiratory and Muscle Metabolic Responses During Conventional Versus Motion Sensor-Assisted Strategies for Functional Electrical Stimulation Standing After Spinal Cord Injury.

This is a case series study with the objective of comparing two motion sensor automated strategies to avert knee buckle during functional electrical stimulation (FES)-standing against a conventional hand-controlled (HC) FES approach. The research was conducted in a clinical exercise laboratory gymnasium at the University of Sydney, Australia. The automated strategies, Aut-A and Aut-B, applied fixed and variable changes of neurostimulation, respectively, in quadriceps amplitude to precisely control knee extension during standing. HC was an "on-demand" increase of stimulation amplitude to maintain stance. Finally, maximal FES amplitude (MA) was used as a control condition, whereby knee buckle was prevented by maximal isometric muscle recruitment. Four AIS-A paraplegics undertook 4 days of testing each, and each assessment day comprised three FES standing trials using the same strategy. Cardiorespiratory responses were recorded, and quadriceps muscle oxygenation was quantified using near-infrared spectroscopy. For all subjects, the longest standing times were observed during Aut-A, followed by Aut-B, and then HC and MA. The standing times of the automated strategies were superior to HC by 9-64%. Apart from a lower heart rates during standing (P = 0.034), the automation of knee extension did not promote different cardiorespiratory responses compared with HC. The standing times during MA were significantly shorter than during the automated or "on-demand" strategies (by 80-250%). In fact, the higher isometric-evoked quadriceps contraction during MA resulted in a greater oxygen demand (P < 0.0001) and wider arteriovenous oxygen extraction (P = 0.08) when compared with the other strategies. In conclusion, even though increased standing times were demonstrated using automated control of knee extension, physiological benefits compared with HC were not evident.

Pancreas and islet transplantation: psychological themes pre- and posttransplant.

PURPOSE OF REVIEW: To date, islet and whole pancreas transplantation have been largely researched and reported separately. Therefore, for the first time, this review seeks to examine together the recently reported psychological issues as they relate to the two different types of transplantation. RECENT FINDINGS: In relation to pancreas transplantation, recent findings indicate potential issues relating to energy levels, including sleep problems; mood problems (anxiety, depression, traumatic stress); social interactions; and identity issues. Similarly, the research on islet allotransplantation (ITA) indicates mood disruptions associated with Type I diabetes mellitus (T1DM), which seem to improve as a result of treatment with ITA. SUMMARY: The review indicates a need for more research to guide effective intervention to optimize psychological recovery post islet and/or pancreas transplantation for patients with T1DM. Effective psychological intervention for this group relies on researchers eliciting more detailed knowledge of pretransplant psychosocial issues, not only in relation to how these might vary by transplant group, but also in relation to patient health status vis-à-vis microvascular complications and glycaemic control, and how these issues change across the whole transplant journey.

Evoked EMG versus muscle torque during fatiguing functional electrical stimulation-evoked muscle contractions and short-term recovery in individuals with spinal cord injury.

This study investigated whether the relationship between muscle torque and m-waves remained constant after short recovery periods, between repeated intervals of isometric muscle contractions induced by functional electrical stimulation (FES). Eight subjects with spinal cord injury (SCI) were recruited for the study. All subjects had their quadriceps muscles group stimulated during three sessions of isometric contractions separated by 5 min of recovery. The evoked-electromyographic (eEMG) signals, as well as the produced torque, were synchronously acquired during the contractions and during short FES bursts applied during the recovery intervals. All analysed m-wave variables changed progressively throughout the three contractions, even though the same muscle torque was generated. The peak to peak amplitude (PtpA), and the m-wave area (Area) were significantly increased, while the time between the stimulus artefact and the positive peak (PosT) were substantially reduced when the muscles became fatigued. In addition, all m-wave variables recovered faster and to a greater extent than did torque after the recovery intervals. We concluded that rapid recovery intervals between FES-evoked exercise sessions can radically interfere in the use of m-waves as a proxy for torque estimation in individuals with SCI. This needs to be further investigated, in addition to seeking a better understanding of the mechanisms of muscle fatigue and recovery.

Physiological and physical characteristics of elite dragon boat paddlers.

The objectives of this study were to profile the physiological and physical characteristics of elite dragon boat paddlers, to identify characteristics that predict race performance and to quantify the metabolic energy contributions to simulated 200-m and 500-m dragon boat racing. Eleven, national level, male, Japanese dragon boat paddlers completed a battery of tests on a paddling ergometer including an incremental maximal aerobic capacity test, a 2-minute maximal accumulated oxygen deficit (MAOD) test, and simulated 200-m and 500-m races. A physiological and physical profile of subjects was compiled. Results showed that 200-m race performance correlated with flexed arm girth and excess postexercise oxygen consumption (EPOC) measured in the 30 minutes after the MAOD test, whereas 500-m race performance correlated with body fat percentage, relaxed and flexed arm girth, MAOD, EPOC, and peak power during the MAOD test. Stepwise multiple regression revealed that flexed arm girth was the most powerful predictor of 200-m and 500-m race performance, followed by EPOC with the combination of these 2 factors able to explain 74% and 68% of the variance in 200-m and 500-m race performance, respectively. Aerobic energy contributions for 200-m (50 seconds) and 500-m (1 minute 50 seconds) races were (mean (95% confidence intervals)) 52.1% (range, 47.4-56.8%) and 67.5% (range, 60.1-77.8%), respectively. In conclusion, coaches should develop training programs targeted at developing upper-body musculature and increasing anaerobic capacity because these factors are the strongest predictors of 200-m and 500-m race performance. Given the substantial aerobic energy contributions even for a 200-m race event, coaches should aim to increase the maximal aerobic capacity of the paddler in preparation for both 200-m and 500-m events.

The dynamics of elite paddling on a kayak simulator.

During kayak paddling, athletes attempt to maximize kayak velocity with the generation of optimal paddle forces. The aim of the current study was to examine ten elite kayakers and identify a number of key biomechanical performance variables during maximal paddling on a custom kayak simulator. These included analysing the effect of side (left and right) and period (beginning, middle, and end of the kayak simulation) on paddle force, paddle angle, mechanical efficiency, and stroke timing data. Paddle kinetics and kinematics were measured with strain gauge force transducers attached to either end of the ergometer paddle and using a 3D motion analysis system respectively. Results indicated a significantly greater mechanical efficiency during the right paddle stroke compared with the left (P < 0.025). In addition, analysing the effect of period, peak paddle force demonstrated a significant reduction when comparing the beginning to the middle and end of the simulated race respectively (P < 0.025). Examination of individual force profiles revealed considerable individuality, with significant variation in the time course of force application. Analysis of the profiles presented may provide meaningful feedback for kayakers and their coaches.

Effect of gender and stroke rate on joint power characteristics of the upper extremity during simulated rowing.

Males typically have greater upper body strength than do females, which is likely to impact on the rowing techniques adopted by each sex. The aim of this study was to quantify energy contributions and compare the joint power production of upper extremity joints between the sexes. Seven males and eight females performed 60 s trials at five different stroke rates. External forces were measured at the handle and stretcher, while kinematics were recorded by motion analysis. Joint moments were derived by inverse dynamic calculations, followed by the calculation of joint powers and gross mechanical energy expenditure. Male rowers expended more total external energy per stroke and made a larger percentage contribution of angular shoulder energy to their total external energy expenditure. As stroke rate increased, the contribution from elbow and angular shoulder energy contributions decreased for both males and females. Female rowers decreased their angular shoulder contribution at a slower rate than did males as stroke rate increased. The overall percentage of work done on the stretcher was higher for male rowers, and this difference further increased at higher stroke rates. The results of this study suggest that specific upper body conditioning may be particularly important for female rowers.

Evoked EMG and muscle fatigue during isokinetic FES-cycling in individuals with SCI.

PURPOSE: This study investigated whether muscle fatigue during functional electrical stimulation (FES)-induced cycling was associated with changes occurring in evoked electromyographic signals (eEMG, M-waves) in individuals with spinal cord injury. We also explored the effects of recovery intervals between exercise sessions on the relationship between eEMG and muscle torque. METHODS: Eight individuals with spinal cord injury performed three FES-cycling sessions of 15-min duration, with 5 min of recovery between them. The quadriceps muscles were electrically stimulated as the prime agonist to produce cycling. Pedal torques and surface eEMG signals were synchronously processed and recorded for offline analysis. RESULTS: Large Torque decreases (20-44%) were observed in the first 5 min of cycling during the three exercise bouts, while changes of similar magnitude did not occur on any of the M-wave time-series (less than 19%). Between 5 and 15 min of cycling, muscle fatigue lowered the plateau baselines of Torque (ranging from 41% to 62%), M-wave peak-to-peak amplitude (PtpA) and Area (ranging from 60% to 98%) time-series, yet the magnitudes of these reductions were not consistent between them. CONCLUSION: We concluded that muscle fatigue during FES-cycling was not associated with, nor could be predicted by, eEMG signals. Nonetheless, the consistency between M-waves and Torque time-curves in their direction of change clearly warrants further investigation.

High Modulation Bandwidth of Semipolar (11-22) InGaN/GaN LEDs with Long Wavelength Emission.

Visible light communication requires III-nitride LEDs with a high modulation bandwidth but have c-plane limitations. General illumination requires green/yellow III-nitride LEDs with high optical efficiency that are difficult to achieve on c-plane substrates. Micro-LEDs with a low efficiency are used to obtain a high modulation bandwidth. This paper demonstrates a record modulation bandwidth of 540 MHz for our semipolar green LEDs with a broad area. Semipolar yellow and amber LEDs with modulation bandwidths of 350 and 140 MHz, respectively, have also been reported, and are the longest wavelength III-nitride LEDs. These results agree with differential carrier lifetime measurements.

Resistive Exercise for Arthritic Cartilage Health (REACH): a randomized double-blind, sham-exercise controlled trial.

BACKGROUND: This article provides the rationale and methodology, of the first randomised controlled trial to our knowledge designed to assess the efficacy of progressive resistance training on cartilage morphology in women with knee osteoarthritis.Development and progression of osteoarthritis is multifactorial, with obesity, quadriceps weakness, joint malalignment, and abnormal mechanical joint forces particularly relevant to this study. Progressive resistance training has been reported to improve pain and disability in osteoarthritic cohorts. However, the disease-modifying potential of progressive resistance training for the articular cartilage degeneration characteristic of osteoarthritis is unknown. Our aim was to investigate the effect of high intensity progressive resistance training on articular cartilage degeneration in women with knee osteoarthritis. METHODS: Our cohort consisted of women over 40 years of age with primary knee osteoarthritis, according to the American College of Rheumatology clinical criteria. Primary outcome was blinded measurement of cartilage morphology via magnetic resonance imaging scan of the tibiofemoral joint. Secondary outcomes included walking endurance, balance, muscle strength, endurance, power, and velocity, body composition, pain, disability, depressive symptoms, and quality of life.Participants were randomized into a supervised progressive resistance training or sham-exercise group. The progressive resistance training group trained muscles around the hip and knee at 80% of their peak strength and progressed 3% per session, 3 days per week for 6 months. The sham-exercise group completed all exercises except hip adduction, but without added resistance or progression. Outcomes were repeated at 3 and 6 months, except for the magnetic resonance imaging scan, which was only repeated at 6 months. DISCUSSION: Our results will provide an evaluation of the disease-modifying potential of progressive resistance training for osteoarthritis. TRIAL REGISTRATION: ANZCTR Reference No. 12605000116628.

The family approach to assessing fit in Rasch measurement.

There has been a renewed interest in comparing the usefulness of a variety of model and non-model based fit statistics to detect measurement disturbances. Most of the recent studies compare the results of individual statistics trying to find the single best statistic. Unfortunately, the nature of measurement disturbances is such that they are quite varied in how they manifest themselves in the data. That is to say, there is not a single fit statistic that is optimal for detecting every type of measurement disturbance. Because of this, it is necessary to use a family of fit statistics designed to detect the most important measurement disturbances when checking the fit of data to the appropriate Rasch model. The early Rasch fit statistics (Wright and Panchapakasen, 1969) were based on the Pearsonian chi square. The ability to recombine the NxL chi squares into a variety of different fit statistics, each looking at specific threats to the measurement process, is critical to this family approach to assessing fit. Calibration programs, such as WINSTEPS and FACETS, that use only one type of fit statistic to assess the fit of the data to the model, seriously underestimate the presence of measurement disturbances in the data. This is due primarily to the fact that the total fit statistics (INFIT and OUTFIT), used exclusively in these programs, are relatively insensitive to systematic threats to unidimensionality. This paper, which focuses on the Rasch model and the Pearsonian chi-square approach to assessing fit, will review the different types or measurement disturbances and their underlying causes, and identify the types of fit statistics that must be used to detect these disturbances with maximum efficiency.

Relative shank to thigh length is associated with different mechanisms of power production during elite male ergometer rowing.

The effect of anthropometric differences in shank to thigh length ratio upon timing and magnitude of joint power production during the drive phase of the rowing stroke was investigated in 14 elite male rowers. Rowers were tested on the RowPerfect ergometer which was instrumented at the handle and foot stretcher to measure force generation, and a nine segment inverse dynamics model used to calculate the rower's joint and overall power production. Rowers were divided into two groups according to relative shank thigh ratio. Time to half lumbar power generation was significantly earlier in shorter shank rowers (p = 0.028) compared to longer shank rowers, who showed no lumbar power generation during the same period of the drive phase. Rowers with a relatively shorter shank demonstrated earlier lumbar power generation during the drive phase resulting from restricted rotation of the pelvic segment requiring increased lumbar extension in these rowers. Earlier lumbar power generation and extension did not appear to directly affect performance measures of the short shank group, and so can be attributed to a technical adaptation developed to maximise rowing performance.

Estimation of decision consistency indices for complex assessments: model based approaches.

With the implementation of the No Child Left Behind assessment program and the use of proficiency levels as a means of evaluating Annual Yearly Progress, there is a renewed interest in the consistency of classification decisions based on scale scores from achievement test and state-wide proficiency standards. Many of the current methods described in the literature (Huynh, 1976; Hanson and Brennan, 1990; and Livingston and Lewis, 1995) are based on assumptions about the distribution of the conditional errors. Although recent methods (Brennan and Wan, 2004) make no assumptions about the distribution, these methods have one compelling disadvantage: the decision consistency calculated is based on the entire set of data and are not conditional on the location of the cut scores, the student measure and the conditional standard errors of measurement for the students. The decision consistency for a student scoring right at the cut score will be much lower that the decision consistency for a student with a score 5 points above or below that cut score. The standard error method described in this article is based solely on the asymptotic standard error of measurement derived from the appropriate Rasch measurement model, and the location of the cut score used to make the classification decision. This classification can be easily modified to accommodate multiple classification categories. This is a conditional decision consistency statistic that can be applied to each person ability estimate (raw score) and provides information that can be used to calculate the likelihood that a person with that measure will receive the same classification if retested. The decision consistency for the entire sample can be calculated by simply summing the likelihood of the same classification over all of the examinees. The results of retest simulations using data that fit the Rasch model suggest that the standard error method provides a better estimate of the resulting classification consistency than the true score methods or the bootstrap method.

Saudi medical students knowledge, attitudes, and beliefs with regard to organ donation and transplantation.

A positive attitude to organ donation among doctors is key to increasing organ donation. Education of medical students is suggested to be central to achieving this. This study examined whether knowledge of organ donation and transplantation (ODT) correlates with attitudes and beliefs relevant to ODT among medical students in Saudi Arabia. Two hundred and thirty-three students completed a self-administered questionnaire. A knowledge score was calculated for each student and correlated with answers on attitudes and beliefs with regard to ODT. This study revealed a complex interaction between knowledge, attitudes, and beliefs to ODT. The majority of students support ODT in general, but a significant proportion have negative beliefs when asked about specific details of the process and concern for family members with regard to both deceased and live donation is evident. Despite almost all students believing that Islamic beliefs do not preclude ODT, 27.1% believe transplantation to be unacceptable in the Society in which they live. Education is an important strategy to improve donation rates. These findings can guide development of medical student education programs suggesting inclusion of open debate about views in society and the importance of discussion with family members to be essential.

The sleep architecture of Saudi Arabian patients with Kleine-Levin syndrome.

OBJECTIVES: To establish baseline sleep architecture during an acute attack of Kleine-Levin syndrome (KLS) in a cohort of Saudi Arabian KLS patients and compare these characteristics with other published cohorts. Methods: This was a retrospective cohort study of the polysomnographic characteristics of 10 typical symptomatic Saudi Arabian KLS patients attending the University Sleep Disorders Center, King Saud University, Riyadh, Saudi Arabia between 2002 and 2015. Data were captured by nocturnal polysomnography during an acute attack of hypersomnia and compared with other published cohorts identified via a systematic literature search.  Results: Self-reported time asleep during episodes (11.1±6.7 hours) and recorded total sleep time (TST) (322.5±108.7 minutes) were generally shorter than other published cohorts. Sleep efficiency was poor at 75.0%±25.1%, with low relative amounts of rapid eye movement (REM) sleep (16.5±5.9% of TST) and deep non-REM sleep (stage N3; 10.5±6.0% of TST) and high relative amounts of non-REM sleep (stage N1; 7.0±4.3% of TST). The sleep architecture of Saudi Arabian KLS patients was similar to other published cohorts.  Conclusions: Sleep architecture of our cohort was relatively normal and broadly similar to other published studies, the main features being low sleep efficiency and low relative amounts of REM and stage N3 sleep. Time-course polysomnography studies with functional imaging may be useful to further establish the exact pathophysiology of this disease.

Atlas Fractures: Diagnosis, Current Treatment Recommendations, and Implications for Elderly Patients.

Fractures of the C1 vertebrae (atlas) are commonly the result of falls and other trauma, which cause hyperextension, or axial compression of the cervical spine. Although historically thought as a benign injury with lower neurological risks, current data suggests that this may not hold true for geriatric patients (aged 65 y and older) who may be predisposed to these fractures even after lower-energy trauma such as ground-level falls. Advancements in orthopedic trauma care has increased our diagnostic abilities to identify and manage patients with C1 fractures and other upper cervical spine trauma. However, there are no universal treatment guidelines based on level I trials. Current treatment ranges from nonoperative to operative management depending on fracture-pattern and integrity of the surrounding ligaments. Furthermore, in the elderly patients these fractures present a unique dilemma due to preexisting comorbidities and contraindications to various treatment modalities. C1 fractures warrant greater recognition to provide optimal treatment to patients and minimize the risk for developing complications. The goal of this review is to highlight the most updated treatment guidelines and to discuss the complications of both operative and nonoperative management of C1 fractures especially among the elderly patient population.

Impact attenuation properties of jazz shoes alter lower limb joint stiffness during jump landings.

OBJECTIVES: To quantify the impact attenuation properties of the jazz shoes, and to investigate the in-vivo effect of four jazz shoe designs on lower limb joint stiffness during a dance-specific jump. DESIGN: Repeated measures. METHODS: A custom-built mechanical shoe tester similar to that used by athletic shoe companies was used to vertically impact the forefoot and heel region of four different jazz shoe designs. Additionally, dancers performed eight sautés in second position in bare feet and the shoe conditions. Force platforms and 3D-motion capture were used to analyse the joint stiffness of the midfoot, ankle, knee and hip during the jump landings. RESULTS: Mechanical testing of the jazz shoes revealed significant differences in impact attenuation characteristics among each of the jazz shoe designs. Gross knee and midfoot joint stiffness were significantly affected by the jazz shoe designs in the dancers' jump landings. CONCLUSIONS: The tested jazz shoe designs altered the impact attenuating capacity of jump landing technique in dancers. The cushioned jazz shoes are recommended particularly for injured dancers to reduce impact on the lower limb. Jazz shoe design should consider the impact attenuation properties of the forefoot region, due to the toe-strike landing technique in dance movement.

The identification of risk factors for ankle sprains sustained during netball participation.

OBJECTIVES: Ankle sprains account for a large percentage of injuries sustained in netball. The identification of risk factors for ankle sprain is the preliminary action required to inform future prevention strategies. DESIGN: Prospective study. PARTICIPANTS: Ninety-four netball players from club and inter-district teams. METHODS: Preseason data were collected for; vertical jump height, perceived ankle instability, sprain history, arthrometry inversion-eversion angles, star excursion balance test reach distances, the number of foot lifts during unilateral stance and demi-pointe balance test results. Participants were followed for the duration of one netball season and ankle sprains were recorded. RESULTS: Eleven sprains were recorded for eleven players using a time-loss definition of injury. Ankle sprains occurred at an incidence rate of 1.74/1000 h of netball exposure. One risk factor was identified to increase the odds of sustaining an ankle sprain during netball participation - a reach distance in the posterior-medial direction of the star excursion balance test of less than or equal to 77.5% of leg length (OR = 4.04, 95% CI = 1.00-16.35). CONCLUSIONS: The identified risk factor can be easily measured and should be considered for preseason injury risk profiling of netball players. Netball players may benefit from training programs aimed at improving single leg balance.