Treatment methods for post-traumatic elbow stiffness caused by heterotopic ossification.

HYPOTHESIS: Heterotopic ossification (HO) is a common complication of surgically treated elbow fractures that can inhibit range of motion and impair quality of life. Although there are many treatment methods for HO, there is a lack of consensus as to the best option. We hypothesized that contracture release combined with Botox injection would lead to improved functional outcome scores when compared with current treatment methods. METHODS: A retrospective review was conducted of patients who presented to a single surgeon with HO secondary to elbow fracture between 2005 and 2018. A total of 59 patients were identified who met inclusion criteria. Data were classified into 3 groups: contracture release (control - CR), Botox injection with CR (Botox + CR), and radiation therapy with CR (CR + RT). Range of motion measurements were obtained, including flexion, extension, pronation, and supination. RESULTS: A total of 30 patients (30 of 59, 50.8%) received CR, 6 (6 of 59, 9.2%) were treated with CR + RT, and 23 (23 of 59, 40.0%) had CR + Botox. There was a significant difference between pre- and postoperative arc of motion for both CR + RT (P < .01) and CR + Botox (P < .01). In addition, there was a significant difference in pre- and postoperative extension for patients who received intraoperative Botox injections (P < .05). There was no significant difference between pre- and postoperative motion nor extension in the CR group. CONCLUSION: Intraoperative Botox injection with CR is an effective method in the treatment of post-traumatic elbow stiffness caused by HO.

The Release 6 reference sequence of the Drosophila melanogaster genome.

Drosophila melanogaster plays an important role in molecular, genetic, and genomic studies of heredity, development, metabolism, behavior, and human disease. The initial reference genome sequence reported more than a decade ago had a profound impact on progress in Drosophila research, and improving the accuracy and completeness of this sequence continues to be important to further progress. We previously described improvement of the 117-Mb sequence in the euchromatic portion of the genome and 21 Mb in the heterochromatic portion, using a whole-genome shotgun assembly, BAC physical mapping, and clone-based finishing. Here, we report an improved reference sequence of the single-copy and middle-repetitive regions of the genome, produced using cytogenetic mapping to mitotic and polytene chromosomes, clone-based finishing and BAC fingerprint verification, ordering of scaffolds by alignment to cDNA sequences, incorporation of other map and sequence data, and validation by whole-genome optical restriction mapping. These data substantially improve the accuracy and completeness of the reference sequence and the order and orientation of sequence scaffolds into chromosome arm assemblies. Representation of the Y chromosome and other heterochromatic regions is particularly improved. The new 143.9-Mb reference sequence, designated Release 6, effectively exhausts clone-based technologies for mapping and sequencing. Highly repeat-rich regions, including large satellite blocks and functional elements such as the ribosomal RNA genes and the centromeres, are largely inaccessible to current sequencing and assembly methods and remain poorly represented. Further significant improvements will require sequencing technologies that do not depend on molecular cloning and that produce very long reads.

Exoskeleton assistance symmetry matters: unilateral assistance reduces metabolic cost, but relatively less than bilateral assistance.

BACKGROUND: Many gait impairments are characterized by asymmetry and result in reduced mobility. Exoskeletons could be useful for restoring gait symmetry by assisting only one leg. However, we still have limited understanding of the effects of unilateral exoskeleton assistance. Our aim was to compare the effects of unilateral and bilateral assistance using a within-subject study design. METHODS: Eleven participants walked in different exoskeleton conditions. In the Unilateral conditions, only one leg was assisted. In Bilateral Matched Total Work, half of the assistance from the Unilateral conditions was applied to both legs such that the bilateral sum was equal to that of the Unilateral conditions. In Bilateral Matched Work Per Leg, the same assistance as in the Unilateral conditions was provided to both legs such that the bilateral sum was the double of that of the Unilateral conditions. In the Powered-Off condition, no assistance was provided. We measured metabolic energy consumption, exoskeleton mechanics and kinematics. RESULTS: On average, the Unilateral, Bilateral Matched Total Work and Bilateral Matched Work Per Leg conditions reduced the metabolic rate by 7, 11 and 15%, respectively, compared with the Powered-Off condition. A possible explanation for why the Unilateral conditions effectively reduced the metabolic rate could be that they caused only very little asymmetry in gait biomechanics, except at the ankle and in the horizontal center-of-mass velocity. We found the highest ratio of metabolic rate reduction versus positive work assistance with bilateral assistance and low work per leg (Bilateral Matched Total Work). Statistical analysis indicated that assistance symmetry and assistance per leg are more important than the bilateral summed assistance for reducing the metabolic rate of walking. CONCLUSIONS: These data bridge the gap between conclusions from studies with unilateral and bilateral exoskeletons and inform how unilateral assistance can be used to influence gait parameters, such as center-of-mass velocity.

Reducing the metabolic cost of walking with an ankle exoskeleton: interaction between actuation timing and power.

BACKGROUND: Powered ankle-foot exoskeletons can reduce the metabolic cost of human walking to below normal levels, but optimal assistance properties remain unclear. The purpose of this study was to test the effects of different assistance timing and power characteristics in an experiment with a tethered ankle-foot exoskeleton. METHODS: Ten healthy female subjects walked on a treadmill with bilateral ankle-foot exoskeletons in 10 different assistance conditions. Artificial pneumatic muscles assisted plantarflexion during ankle push-off using one of four actuation onset timings (36, 42, 48 and 54% of the stride) and three power levels (average positive exoskeleton power over a stride, summed for both legs, of 0.2, 0.4 and 0.5 W∙kg-1). We compared metabolic rate, kinematics and electromyography (EMG) between conditions. RESULTS: Optimal assistance was achieved with an onset of 42% stride and average power of 0.4 W∙kg-1, leading to 21% reduction in metabolic cost compared to walking with the exoskeleton deactivated and 12% reduction compared to normal walking without the exoskeleton. With suboptimal timing or power, the exoskeleton still reduced metabolic cost, but substantially less so. The relationship between timing, power and metabolic rate was well-characterized by a two-dimensional quadratic function. The assistive mechanisms leading to these improvements included reducing muscular activity in the ankle plantarflexors and assisting leg swing initiation. CONCLUSIONS: These results emphasize the importance of optimizing exoskeleton actuation properties when assisting or augmenting human locomotion. Our optimal assistance onset timing and average power levels could be used for other exoskeletons to improve assistance and resulting benefits.

Outcomes of Elbow Arthroscopic Osteocapsular Arthroplasty.

PURPOSE: To evaluate the results of elbow arthroscopic osteocapsular arthroplasty (AOA) and determine which factors influence the outcome in a large group of patients with primary osteoarthritis. METHODS: A consecutive series of 46 patients with elbow osteoarthritis underwent AOA by a single surgeon (N.G.H.) between December 2005 and January 2013. Thirty-one patients returned for a comprehensive physical examination an average of 3.4 years later. The outcomes measures included visual analog scale (VAS), Mayo Elbow Performance Scores (MEPS), Disabilities of the Arm, Shoulder, and Hand (DASH), and American Shoulder and Elbow Society (ASES) scores. Preoperative and postoperative continuous variables were compared and a multivariable regression analysis was performed. RESULTS: Thirty-one patients with a mean age of 48 years (range, 19-77 years) returned for final follow-up, including 27 men and 4 women. Statistically significant improvement was observed in extension deficit (24° before surgery to 12° after surgery), flexion (126° before surgery to 135° after surgery), visual analog scale (6.4 before surgery to 1.6 after surgery), and Mayo Elbow Performance Scores (57 [poor] before surgery to 88 [good] after surgery). Subjective scores included a mean postoperative Disabilities of the Arm, Shoulder, and Hand score of 13 and an American Shoulder and Elbow Society pain score of 40. No complications were noted at final follow-up. CONCLUSIONS: Elbow AOA is a safe, efficacious treatment for patients with mild to moderate osteoarthritis. Our retrospective review found significant improvement in elbow motion, pain and clinical outcomes.

Enhancing performance during inclined loaded walking with a powered ankle-foot exoskeleton.

PURPOSE: A simple ankle-foot exoskeleton that assists plantarflexion during push-off can reduce the metabolic power during walking. This suggests that walking performance during a maximal incremental exercise could be improved with an exoskeleton if the exoskeleton is still efficient during maximal exercise intensities. Therefore, we quantified the walking performance during a maximal incremental exercise test with a powered and unpowered exoskeleton: uphill walking with progressively higher weights. METHODS: Nine female subjects performed two incremental exercise tests with an exoskeleton: 1 day with (powered condition) and another day without (unpowered condition) plantarflexion assistance. Subjects walked on an inclined treadmill (15%) at 5 km h(-1) and 5% of body weight was added every 3 min until exhaustion. RESULTS: At volitional termination no significant differences were found between the powered and unpowered condition for blood lactate concentration (respectively, 7.93 ± 2.49; 8.14 ± 2.24 mmol L(-1)), heart rate (respectively, 190.00 ± 6.50; 191.78 ± 6.50 bpm), Borg score (respectively, 18.57 ± 0.79; 18.93 ± 0.73) and VO2 peak (respectively, 40.55 ± 2.78; 40.55 ± 3.05 ml min(-1) kg(-1)). Thus, subjects were able to reach the same (near) maximal effort in both conditions. However, subjects continued the exercise test longer in the powered condition and carried 7.07 ± 3.34 kg more weight because of the assistance of the exoskeleton. CONCLUSION: Our results show that plantarflexion assistance during push-off can increase walking performance during a maximal exercise test as subjects were able to carry more weight. This emphasizes the importance of acting on the ankle joint in assistive devices and the potential of simple ankle-foot exoskeletons for reducing metabolic power and increasing weight carrying capability, even during maximal intensities.

Margin convergence anchorage to bone for reconstruction of the anterior attachment of the rotator cable.

PURPOSE: The purpose of this study was to compare the biomechanical characteristics of a massive L-shaped retracted rotator cuff tear repaired with either soft-tissue side-to-side sutures or margin convergence anchorage to bone. METHODS: Eight matched pairs of cadaveric shoulders were used. The supraspinatus and infraspinatus were secured in a clamp at 30° of glenohumeral abduction. The subscapularis was secured in a separate clamp, and a constant load was applied. A massive L-shaped rotator cuff tear of the supraspinatus and infraspinatus tendon was created. In all specimens the posterior aspect of the tear was repaired by a transosseous-equivalent technique. In 1 group we placed 2 margin convergence sutures between the supraspinatus and the rotator interval. In the comparison group, a suture anchor was inserted at the anterior attachment of the rotator cable. Margin convergence anchorage to bone was then performed between the supraspinatus and the rotator interval. Each specimen was tested with an Instron machine (Instron, Canton, MA) and a video digitizing system. A paired t test was used for statistical analysis. RESULTS: Margin convergence anchorage to bone decreased gap formation at cycle 1, cycle 30, and yield load across the entire footprint (P < .05). In both constructs the anterior gap was greater than the posterior gap at cycle 1, cycle 30, and yield load (P < .05). Margin convergence anchorage to bone decreased hysteresis and increased stiffness during the first cycle and increased yield load (P < .05). CONCLUSIONS: Using margin convergence anchorage to bone to restore the anterior attachment of the rotator cable decreased gap formation across the entire footprint and improved biomechanical properties for cycle 1 and yield load compared with soft-tissue margin convergence for massive rotator cuff repairs. CLINICAL RELEVANCE: Repairing the anterior rotator cuff with margin convergence anchorage to bone may improve clinical outcomes of an L-shaped massive tear repair.

Flexor tenosynovectomy in carpal tunnel syndrome as a screening tool for early diagnosis of amyloidosis.

INTRODUCTION: Amyloidosis is a heterogeneous group of diseases that most often presents with advanced cardiac pathology. Another presentation of the disease can include symptoms consistent with carpal tunnel syndrome; however, the true incidence of amyloidosis in patients with carpal tunnel syndrome remains unclear. METHODS: We performed a retrospective chart review on all patients who underwent an open carpal tunnel release, with tenosynovium biopsy by a single surgeon between 01/2000 and 12/2018. Samples were stored in formalin following hematoxylin-eosin or congo red staining. A total of 199 patients were excluded for incomplete records, and carpal tunnel release performed for traumatic or infectious etiologies. Histologic findings of the attending pathologist were examined and categorized as follows: amyloidosis, fibrous tissue, tenosynovitis/inflammation edematous, benign tenosynovium, and gout. RESULTS: Exactly 898 open carpal tunnel releases were performed, and 699 patients were included for final analysis. In all patients, biopsies for histology with hematoxylin-eosin (HE) staining were taken; in those HE stains where amylogenic proteins were suspected (73 or 10.4%), a subsequent congo red staining was additionally performed which confirmed the diagnosis of amyloidosis in 10 patients (1.4% of the carpal tunnel procedures). Overall, 10 patients were identified and constituted 1.4% of all HE stains (n = 10/699) and 13.7% of all congo red stains (n = 10/73). CONCLUSION: Our results suggest that the incidence of amyloidosis in the general CTS patient population may be as high as 1.4% with routine screening by synovial biopsy and the diagnosis should be considered as a potential cause. Level of Evidence: III, retrospective study.

Relationship between duty factor and external forces in slow recreational runners.

OBJECTIVES: Recreational runners show a large interindividual variation in spatiotemporal characteristics. This research focused on slow runners and intended: (1) to document the variance in duty factor (DF) between runners in a real-life running setting and (2) examine whether the interindividual variation in DF and stride frequency (SF) relates to differences in external loading parameters between runners. METHODS: Spatiotemporal characteristics of 23 slow runners (ie, <2.6 m/s) were determined during a 5.2 km running event. To relate the interindividual variation in DF and SF to differences in external forces between runners (maximal vertical ground reaction force (FzMax), peak braking force (PBF) and vertical instantaneous loading rate (VILR)), 14 of them were invited to the lab. They ran at 1.9 m/s on a treadmill while ground reaction forces were recorded. A multiple linear regression analysis was conducted to investigate the effect of DF and SF on external force measures. RESULTS: DF between slow runners varied from 42.50% to 56.49% in a recreational running event. DF was found to be a significant predictor of FzMax (R²=0.755) and PBF (R²=0.430). SF only improved the model for PBF, but to a smaller extent than DF (R² change=0.191). For VILR, neither DF nor SF were significant predictors. CONCLUSION: External forces are lower in recreational runners that run with higher DFs and slightly lower SFs. These findings may be important for injury prevention purposes, especially directed to recreational runners that are more prone to overuse injuries.

Kienböck Disease: Quality, Accuracy, and Readability of Online Information.

Background: Patients with limited health literacy require online educational materials to be written below a sixth grade level for optimal understanding. We assessed the quality, accuracy, and readability of online materials for Kienböck disease (KD). Methods: "Kienbock's Disease" and "Lunate Avacular Necrosis" were entered into 3 search engines. The first 25 Web sites from each search were collected. Quality was assessed via a custom grading rubric, accuracy by 2 residents and a fellow, and readability by Flesch-Kincaid grade level (FKGL) and New Dale-Chall test. Web sites were stratified according to the search term, FKGL, order of appearance, and authorship type. Results: A total of 38 unique Web sites were included, of which 22 were assigned to "KD" and 16 to "Lunate Avascular Necrosis." The average quality score out of 30, accuracy score out of 12, and FKGL for all Web sites were 13.3 ± 7.3, 10.4 ± 1.9, and 10.5 ± 1.4, respectively. Web sites assigned to the term "Kienbock's Disease" had a significantly higher FKGL. Web sites of higher FKGL had significantly worse accuracy scores. Order of appearance had no influence. Physician specialty societies (PSS) had a significantly lower FKGL than Web sites of other authorship types. Conclusions: Despite concerted efforts by national organizations, the readability of online patient materials is above the recommended level for KD. Patients with limited health literacy will be most affected by this reality. Until readability improves, patients should continue to consult their physicians when uncertain and prioritize Web sites that are easier to read and produced by PSS.

Complications of Radial Column Plating of the Distal Radius.

Background: Distal radius fractures treated with open reduction and internal fixation are commonly stabilized with a volar locking plate; however, more complex fracture patterns may require supplemental fixation with fragment-specific implants. The objective of this study was to evaluate the outcomes of distal radius fractures treated with radial column plates. Methods: A consecutive series of 61 patients who sustained distal radius fractures underwent radial column plating alone or in conjunction with other implants between August 2006 and January 2014. Thirty-one patients returned for follow-up or returned a mailed questionnaire at an average of 4.1 years. The outcomes measures included Visual Analog Scale (VAS); Disabilities of the Arm, Shoulder and Hand (DASH); and Patient-Rated Wrist Evaluation (PRWE) scores. Results: Sixty-one patients with a mean age of 55 years (range, 20-87) met inclusion criteria and were available for follow-up or chart review at an average of 5.2 years (range, 1.6-9.0 years). Seventeen of 61 (28%) underwent radial column plate removal. Twenty patients returned for final follow-up examination, and 11 completed questionnaires via mail. Subjective scores included a mean postoperative VAS of 0.72, DASH score of 17.2, and PRWE score of 15.7. Hardware sensitivity and wrist stiffness were the most common complications at final follow-up. Conclusions: Radial column plating of the distal radius is a safe treatment modality and a valuable adjunct in the setting of complex distal radius fractures, but patients should be counseled that there is a 28% chance that hardware removal may be required. Our retrospective review found evidence of few complications and objective scores consistent with return to normal function.

Running speed-induced changes in foot contact pattern influence impact loading rate.

Purpose. We aimed to determine the effect of speed-induced changes in foot contact patterns on the vertical instantaneous loading rate (VILR). We hypothesized that transition runners, i.e. runners that shift towards a mid- (MF) or forefoot contact pattern (FF) when running speed increases, show smaller increases in VILR than non-transition runners, i.e. runners that remain with a rearfoot contact pattern (RF). Methods. Fifty-two male and female runners ran overground at 3.2, 4.1, 5.1 and 6.2 m s-1. Ground reaction forces, lower limb sagittal plane knee and ankle kinematics and plantar pressures were recorded. Multi-level linear regression models were used to assess differences between transition and non-transition runners. Results. Non-transition runners experienced larger speed-induced increases in VILR (48.6 ± 2.6 BW s-1 per m s-1) than transition runners (-1.4 ± 7.6 BW s-1 per m s-1). Transition runners showed higher VILRs and a more flat foot touch down at the same pre-transition speed than non-transition runners. Conclusion. When running speed increases, some runners transition towards more anterior foot contact patterns. This reduces or even eliminates the speed-induced increase in VILR. This result is especially the case for those RF runners who already have relatively high VILRs and flat foot positioning at slower running speeds.

Grounded Running Reduces Musculoskeletal Loading.

PURPOSE: Recent observations demonstrate that a sizeable proportion of the recreational running population runs at rather slow speeds and does not always show a clear flight phase. This study determined the key biomechanical and physiological characteristics of this running pattern, i.e., grounded running (GR), and compared these characteristics with slow aerial running (SAR) and reference data on walking at the same slow running speed. METHODS: Thirty male subjects performed instructed GR and SAR at 2.10 m·s on a treadmill. Ground reaction forces, tibial accelerations, and metabolic rate were measured to estimate general musculoskeletal loading (external power and maximal vertical ground reaction force), impact intensity (vertical instantaneous loading rate and tibial acceleration), and energy expenditure. More explicit measures of muscular loading (muscle stresses and peak eccentric power) were calculated based on a representative subsample, in which detailed kinematics and kinetics were recorded. We hypothesized that all measures would be lower for the GR condition. RESULTS: Subjects successfully altered their running pattern upon a simple instruction toward a GR pattern by increasing their duty factor from 41.5% to 51.2%. As hypothesized, impact intensity, general measures for musculoskeletal, and the more explicit measures for muscular loading decreased by up to 35.0%, 20.3%, and 34.0%, respectively, compared with SAR. Contrary to our hypothesis, metabolic rate showed an increase of 4.8%. CONCLUSIONS: Changing running style from SAR to GR reduces musculoskeletal loading without lowering the metabolic energy requirements. As such, GR might be beneficial for most runners as it has the potential to reduce the risk of running-related injuries while remaining a moderate to vigorous form of physical activity, contributing to fulfillment of the recommendations concerning physical activity and public health.

Altering gait variability with an ankle exoskeleton.

Exoskeletons can influence human gait. A healthy gait is characterized by a certain amount of variability compared to a non-healthy gait that has more inherent variability; however which exoskeleton assistance parameters are necessary to avoid increasing gait variability or to potentially lower gait variability below that of unassisted walking are unknown. This study investigated the interaction effects of exoskeleton timing and power on gait variability. Ten healthy participants walked on a treadmill with bilateral ankle-foot exoskeletons under ten conditions with different timing (varied from 36% to 54% of the stride) and power (varied from 0.2 to 0.5 W∙kg-1) combinations. We used the largest Lyapunov exponent (LyE) and maximum Floquet multiplier (FM) to evaluate the stride-to-stride fluctuations of the kinematic time series. We found the lowest LyE at the ankle and a significant reduction versus powered-off with exoskeleton power (summed for both legs) of 0.45 W∙kg-1 and actuation timing at 48% of the stride cycle. At the knee, a significant positive effect of power and a negative interaction effect of power and timing were found for LyE. We found significant positive interaction effects of the square of timing and power for LyE at the knee and hip joints. In contrast, the FM at the ankle increased with increasing power and later timing. We found a significant negative effect of power and a positive interaction effect of power and timing for FM at the knee and no significant effects of any of the exoskeleton parameters for FM at the hip. The ability of the exoskeleton to reduce the LyE at the ankle joint offers new possibilities in terms of altering gait variability, which could have applications for using exoskeletons as rehabilitation devices. Further efforts could examine if it is possible to simultaneously reduce the LyE and FM at one or more lower limb joints.

Bi-articular Knee-Ankle-Foot Exoskeleton Produces Higher Metabolic Cost Reduction than Weight-Matched Mono-articular Exoskeleton.

The bi-articular m. gastrocnemius and the mono-articular m. soleus have different and complementary functions during walking. Several groups are starting to use these biological functions as inspiration to design prostheses with bi-articular actuation components to replace the function of the m. gastrocnemius. Simulation studies indicate that a bi-articular configuration and spring that mimic the m. gastrocnemius could be beneficial for orthoses or exoskeletons. Our aim was to test the effect of a bi-articular and spring configuration that mimics the m. gastrocnemius and compare this to a no-spring and mono-articular configuration. We tested nine participants during walking with knee-ankle-foot exoskeletons with dorsally mounted pneumatic muscle actuators. In the bi-articular plus spring condition the pneumatic muscles were attached to the thigh segment with an elastic cord. In the bi-articular no-spring condition the pneumatic muscles were also attached to the thigh segment but with a non-elastic cord. In the mono-articular condition the pneumatic muscles were attached to the shank segment. We found the highest reduction in metabolic cost of 13% compared to walking with the exoskeleton powered-off in the bi-articular plus spring condition. Possible explanations for this could be that the exoskeleton delivered the highest total positive work in this condition at the ankle and the knee and provided more assistance during the isometric phase of the biological plantarflexors. As expected we found that the bi-articular conditions reduced m. gastrocnemius EMG more than the mono-articular condition but this difference was not significant. We did not find that the mono-articular condition reduces the m. soleus EMG more than the bi-articular conditions. Knowledge of specific effects of different exoskeleton configurations on metabolic cost and muscle activation could be useful for providing customized assistance for specific gait impairments.

Biomechanics of posterior shoulder instability - current knowledge and literature review.

Posterior instability of the shoulder is a rare condition and represents about 10% of shoulder instability. It has become more frequently recognized in the last year, even though it is more difficult to diagnose than anterior shoulder instability. As this form of shoulder pathology is somewhat rare, biomechanical knowledge is limited. The purpose of our study was to perform an extensive literature search, including PubMed and Medline, and to give an overview of the current knowledge on the biomechanics of posterior shoulder instability. The PubMed/Medline databases were utilized, and all articles related to posterior shoulder instability and biomechanics were included to form a comprehensive compilation of current knowledge. A total of 93 articles were deemed relevant according to our inclusion and exclusion criteria. As expected with any newly acknowledged pathology, biomechanical studies on posterior shoulder instability remain limited in the literature. Current biomechanical models are performed in a static manner, which limits their translation for explaining a dynamic pathology. Newer models should incorporate dynamic stabilization of both the rotator cuff and scapulothoracic joint. There is a current lack of knowledge with regards to the pathomechanism of posterior shoulder instability, with no consensus on appropriate treatment regimens. Further investigation is therefore required at both basic science and clinical levels.

A simple exoskeleton that assists plantarflexion can reduce the metabolic cost of human walking.

BACKGROUND: Even though walking can be sustained for great distances, considerable energy is required for plantarflexion around the instant of opposite leg heel contact. Different groups attempted to reduce metabolic cost with exoskeletons but none could achieve a reduction beyond the level of walking without exoskeleton, possibly because there is no consensus on the optimal actuation timing. The main research question of our study was whether it is possible to obtain a higher reduction in metabolic cost by tuning the actuation timing. METHODOLOGY/PRINCIPAL FINDINGS: We measured metabolic cost by means of respiratory gas analysis. Test subjects walked with a simple pneumatic exoskeleton that assists plantarflexion with different actuation timings. We found that the exoskeleton can reduce metabolic cost by 0.18±0.06 W kg(-1) or 6±2% (standard error of the mean) (p = 0.019) below the cost of walking without exoskeleton if actuation starts just before opposite leg heel contact. CONCLUSIONS/SIGNIFICANCE: The optimum timing that we found concurs with the prediction from a mathematical model of walking. While the present exoskeleton was not ambulant, measurements of joint kinetics reveal that the required power could be recycled from knee extension deceleration work that occurs naturally during walking. This demonstrates that it is theoretically possible to build future ambulant exoskeletons that reduce metabolic cost, without power supply restrictions.

Anthropometric and aesthetic analysis of the Indian American woman's face.

BACKGROUND: This is the first study defining the facial anthropometric and aesthetic measurements in Indian American women (IAW). METHODS: This is a prospective cohort study involving evaluation of facial photographs. Frontal, lateral and basal photographs were taken of IAW (n=102), and 30 anthropometric measurements were determined. Proportions were compared with published North American white women (NAWW) norms. Judges (n=6) evaluated the photographs for aesthetics using a visual analogue scale. Attractive IAW (top 15%) were compared with average IAW (remaining 85%) and average NAWW. All completed a facial self-esteem survey. RESULTS: There were significant differences between IAW and NAWW in 25 of 30 facial measurements. Six measurements correlated with aesthetic scores: intercanthal distance, mouth width, nasolabial angle, midface height 2, ear length and nasal height. Attractive IAW had nine measurements approximating NAWW features, 15 measurements similar to average IAW values and two measurements distinct from both average IAW and average NAWW. Attractive IAW had higher facial self-esteem scores than average IAW. CONCLUSIONS: Facial measurements in IAW are much different from NAWW, and these results will assist in preoperative planning. Several features are correlated with attractiveness in IAW: larger and wider-set eyes, a smaller midface, a smaller nose with greater tip rotation, smaller ears and a larger mouth. Attractive IAW display many measurements typical of average IAW and several measurements that reflect average NAWW values. These results contribute to concepts of transcultural aesthetics--for a minority ethnic group, facial beauty appears to be an assimilation of deep-rooted ethnic features with prevailing cultural traits and aesthetic standards.