Adaptations for bipedal walking: Musculoskeletal structure and three-dimensional joint mechanics of humans and bipedal chimpanzees (Pan troglodytes).

Humans are unique among apes and other primates in the musculoskeletal design of their lower back, pelvis, and lower limbs. Here, we describe the three-dimensional ground reaction forces and lower/hindlimb joint mechanics of human and bipedal chimpanzees walking over a full stride and test whether: 1) the estimated limb joint work and power during the stance phase, especially the single-support period, is lower in humans than bipedal chimpanzees, 2) the limb joint work and power required for limb swing is lower in humans than in bipedal chimpanzees, and 3) the estimated total mechanical power during walking, accounting for the storage of passive elastic strain energy in humans, is lower in humans than in bipedal chimpanzees. Humans and bipedal chimpanzees were compared at matched dimensionless and dimensional velocities. Our results indicate that humans walk with significantly less work and power output in the first double-support period and the single-support period of stance, but markedly exceed chimpanzees in the second double-support period (i.e., push-off). Humans generate less work and power in limb swing, although the species difference in limb swing power was not statistically significant. We estimated that total mechanical positive 'muscle fiber' work and power were 46.9% and 35.8% lower, respectively, in humans than in bipedal chimpanzees at matched dimensionless speeds. This is due in part to mechanisms for the storage and release of elastic energy at the ankle and hip in humans. Furthermore, these results indicate distinct 'heel strike' and 'lateral balance' mechanics in humans and bipedal chimpanzees and suggest a greater dissipation of mechanical energy through soft tissue deformations in humans. Together, our results document important differences between human and bipedal chimpanzee walking mechanics over a full stride, permitting a more comprehensive understanding of the mechanics and energetics of chimpanzee bipedalism and the evolution of hominin walking.

The loss of the 'pelvic step' in human evolution.

Human bipedalism entails relatively short strides compared with facultatively bipedal primates. Unique non-sagittal-plane motions associated with bipedalism may account for part of this discrepancy. Pelvic rotation anteriorly translates the hip, contributing to bipedal stride length (i.e. the 'pelvic step'). Facultative bipedalism in non-human primates entails much larger pelvic rotation than in humans, suggesting that a larger pelvic step may contribute to their relatively longer strides. We collected data on the pelvic step in bipedal chimpanzees and over a wide speed range of human walking. At matched dimensionless speeds, humans have 26.7% shorter dimensionless strides, and a pelvic step 5.4 times smaller than bipedal chimpanzees. Differences in pelvic rotation explain 31.8% of the difference in dimensionless stride length between the two species. We suggest that relative stride lengths and the pelvic step have been significantly reduced throughout the course of hominin evolution.

A Multicenter Comparison of Complementary and Alternative Medicine (CAM) Discussions in Oncology Care: The Role of Time, Patient-Centeredness, and Practice Context.

BACKGROUND: Little is known about how complementary and alternative medicine (CAM) is discussed in cancer care across varied settings in the U.S. METHODS: In two practices affiliated with one academic medical center in southern California (SoCal), and one in the upper Midwest (UM), we audio-recorded patient-clinician interactions in medical oncology outpatient practices. We counted the frequency and duration of CAM-related conversations. We coded recordings using the Roter Interaction Analysis System. We used chi-square tests for bivariate analysis of categorical variables and generalized linear models for continuous variables to examine associations between dialogue characteristics, practice setting, and population characteristics with the occurrence of CAM discussion in each setting followed by multivariate models adjusting for clinician clustering. RESULTS: Sixty-one clinicians and 529 patients participated. Sixty-two of 529 (12%) interactions included CAM discussions, with significantly more observed in the SoCal university practice than in the other settings. Visits that included CAM were on average 6 minutes longer, with CAM content lasting an average of 78 seconds. In bivariate tests of association, conversations containing CAM included more psychosocial statements from both clinicians and patients, higher patient-centeredness, more positive patient and clinician affect, and greater patient engagement. In a multivariable model including significant bivariate terms, conversations containing CAM were independently associated with higher patient-centeredness, slightly longer visits, and being at the SoCal university site. CONCLUSION: The frequency of CAM-related discussion in oncology varied substantially across sites. Visits that included CAM discussion were longer and more patient centered. IMPLICATIONS FOR PRACTICE: The Institute of Medicine and the American Society of Clinical Oncology have called for more open discussions of complementary and alternative medicine (CAM). But little is known about the role population characteristics and care contexts may play in the frequency and nature of those discussions. The present data characterizing actual conversations in practice complements a much larger literature based on patient and clinician self-report about CAM disclosure and use. It was found that CAM discussions in academic oncology visits varied significantly by practice context, that the majority were initiated by the patient, and that they may occur more when visit time exists for lifestyle, self-care, and psychosocial concerns.

Great ape thorax and shoulder configuration-An adaptation for arboreality or knuckle-walking?

Great apes exhibit a suite of morphological traits of the shoulder and upper thorax that have traditionally been linked to orthograde arborealism. Recently it has been proposed that these traits are instead adaptations for knuckle-walking, and more broadly, that knuckle-walking itself is an adaptation for shock absorption during terrestriality. Here we test several tenets of these hypotheses using kinematic and kinetic data from chimpanzees and macaques, and electromyographic data of shoulder muscle activity in chimpanzees. We collected 3D kinematic data to quantify motion of the acromion and trunk during quadrupedalism and vertical climbing in chimpanzees as well as ground reaction forces to investigate the presence and magnitude of impact transient forces during terrestrial locomotion in chimpanzees and macaques. We also investigated patterns of recruitment of select forelimb musculature (triceps brachii and serratus anterior) using previously collected data in chimpanzees to determine whether these muscles may function to absorb impact transient forces. We found that the acromion is significantly more elevated in vertical climbing than during knuckle-walking, while dorsoventral ranges and magnitudes of motion were similar between gaits. Ground reaction forces indicate that only a minority of strides in either chimpanzees or macaques have transient forces and, when present, these transient forces as well as loading rates are small. Electromyographic results show that activity of the triceps brachii may facilitate energy absorption while serratus anterior likely functions to support the trunk, as in other primates. Our data suggest there is little to no evidence supporting recent hypotheses that the African ape upper thorax and shoulder configuration is an adaptation for knuckle-walking, or more broadly, that knuckle-walking exists as an adaptation to absorb impact shock during terrestriality. We do however find some evidence that shoulder configuration allows greater scapular elevation in chimpanzees during arboreal behaviors (e.g., vertical climbing).

Investigator Disclosure and Advanced Cancer Patient Understanding of Informed Consent and Prognosis in Phase I Clinical Trials.

PURPOSE: Advanced cancer patients (ACPs) who participate in phase I clinical trials often report a less-than-ideal understanding of the required elements of informed consent (IC) and unrealistic expectations for anticancer benefit and prognosis. We examined phase I clinical trial enrollment discussions and their associations with subsequent ACP understanding. METHODS: Clinical encounters about enrollment in phase I trials between 101 ACPs and 29 oncologists (principal investigators [PIs] and fellows) at three US academic medical institutions were recorded. The Roter Interaction Analysis System was used for analysis. ACPs completed follow-up questionnaires to assess IC recall. RESULTS: PIs disclosed the following phase I IC elements to ACPs in encounters: trial purpose in 40%; specific physical risks in 60%; potential specific medical benefits gained by trial participation (eg, disease stabilization) in 48.2%; and alternatives to phase I trial participation in 47.1%, with 1.1% of encounters containing palliative and 2.3% hospice information. PIs provided ACP-specific prognoses in 29.0% of encounters but used precise terms of death in only 4.7% and terminal in 1.2%. A significant association existed between PI disclosure of the trial purpose as dosage/toxicity, and ACPs subsequently correctly recalled trial purpose versus PIs who did not disclose it (85% v 13%; P < .05). CONCLUSION: Many oncologists provide incomplete disclosures about phase I trials to ACPs. When disclosure of certain elements of IC occurs, it seems to be associated with better recall, especially with regard to the research purpose of phase I trials.

Family companions' involvement during pre-surgical consent visits for major cancer surgery and its relationship to visit communication and satisfaction.

OBJECTIVE: To examine the association between family companion presence during pre-surgical visits to discuss major cancer surgery and patient-provider communication and satisfaction. METHODS: Secondary analysis of 61 pre-surgical visit recordings with eight surgical oncologists at an academic tertiary care hospital using the Roter Interaction Analysis System (RIAS). Surgeons, patients, and companions completed post-visit satisfaction questionnaires. Poisson and logistic regression models assessed differences in communication and satisfaction when companions were present vs. absent. RESULTS: There were 46 visits (75%) in which companions were present, and 15 (25%) in which companions were absent. Companion communication was largely emotional and facilitative, as measured by RIAS. Companion presence was associated with more surgeon talk (IRR 1.29, p = 0.006), and medical information-giving (IRR 1.41, p = 0.001). Companion presence was associated with less disclosure of lifestyle/psychosocial topics by patients (IRR 0.55, p = 0.037). In adjusted analyses, companions' presence was associated with lower levels of patient-centeredness (IRR 0.77, p 0.004). There were no differences in patient or surgeon satisfaction based on companion presence. CONCLUSION: Companions' presence during pre-surgical visits was associated with patient-surgeon communication but was not associated with patient or surgeon satisfaction. PRACTICE IMPLICATIONS: Future work is needed to develop interventions to enhance patient-companion-provider interactions in this setting.

Chimpanzee super strength and human skeletal muscle evolution.

Since at least the 1920s, it has been reported that common chimpanzees (Pan troglodytes) differ from humans in being capable of exceptional feats of "super strength," both in the wild and in captive environments. A mix of anecdotal and more controlled studies provides some support for this view; however, a critical review of available data suggests that chimpanzee mass-specific muscular performance is a more modest 1.5 times greater than humans on average. Hypotheses for the muscular basis of this performance differential have included greater isometric force-generating capabilities, faster maximum shortening velocities, and/or a difference in myosin heavy chain (MHC) isoform content in chimpanzee relative to human skeletal muscle. Here, we show that chimpanzee muscle is similar to human muscle in its single-fiber contractile properties, but exhibits a much higher fraction of MHC II isoforms. Unlike humans, chimpanzee muscle is composed of ∼67% fast-twitch fibers (MHC IIa+IId). Computer simulations of species-specific whole-muscle models indicate that maximum dynamic force and power output is 1.35 times higher in a chimpanzee muscle than a human muscle of similar size. Thus, the superior mass-specific muscular performance of chimpanzees does not stem from differences in isometric force-generating capabilities or maximum shortening velocities-as has long been suggested-but rather is due in part to differences in MHC isoform content and fiber length. We propose that the hominin lineage experienced a decline in maximum dynamic force and power output during the past 7-8 million years in response to selection for repetitive, low-cost contractile behavior.

Communication predictors and consequences of Complementary and Alternative Medicine (CAM) discussions in oncology visits.

OBJECTIVE: Cancer patients use complementary and alternative medicine (CAM), but do not routinely talk about it with their clinicians. This study describes CAM discussions in oncology visits, the communication patterns that facilitate these discussions and their association with visit satisfaction. METHODS: 327 patients (58% female; average age 61) and 37 clinicians were recorded during an oncology visit and completed post-visit questionnaires. All CAM discussions were tagged and the Roter Interaction Analysis System (RIAS) was used to code visit dialogue. RESULTS: CAM was discussed in 36 of 327 visits; discussions were brief (

Family Conferences in the Neonatal ICU: Observation of Communication Dynamics and Contributions.

OBJECTIVES: Clinicians in the neonatal ICU must engage in clear and compassionate communication with families. Empirical, observational studies of neonatal ICU family conferences are needed to develop counseling best practices and to train clinicians in key communication skills. We devised a pilot study to record and analyze how interdisciplinary neonatal ICU clinicians and parents navigate difficult conversations during neonatal ICU family conferences. DESIGN: We prospectively identified and audiotaped a convenience sample of neonatal ICU family conferences about "difficult news." Conversations were analyzed using the Roter interaction analysis system, a quantitative tool for assessing content and quality of patient-provider communication. SETTING: An urban academic children's medical center with a 45-bed level IV neonatal ICU. SUBJECTS: Neonatal ICU parents and clinicians. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: We analyzed 19 family conferences that included 31 family members and 23 clinicians. The child's mother was included in all conferences, and a second parent, usually the father, was present in 13 conferences. All but one conference included multiple medical team members. On average, physicians contributed 65% of all dialogue, regardless of who else was present. Over half (56%) of this dialogue involved giving medical information; under 5% of clinician dialogue involved asking questions of the family, and families rarely (5% of dialogue) asked questions. Conversations were longer with the presence of nonphysician clinicians, but this did not increase the amount of dialogue about psychosocial information or increase parent dialogue. CONCLUSIONS: We collected a novel repository of audio-recorded neonatal ICU family meetings that offers insights into discussion content and process. These meetings were heavily focused on biomedical information even when interdisciplinary clinicians were present. Clinicians always talked more than parents, and no one asked many questions. Maximizing the participation of interdisciplinary clinicians in neonatal ICU family meetings may require explicit strategies. Methods to increase family engagement should be targeted.

Distinct functional roles of primate grasping hands and feet during arboreal quadrupedal locomotion.

It has long been thought that quadrupedal primates successfully occupy arboreal environments, in part, by relying on their grasping feet to control balance and propulsion, which frees their hands to test unstable branches and forage. If this interlimb decoupling of function is real, there should be discernible differences in forelimb versus hind limb musculoskeletal control, specifically in how manual and pedal digital flexor muscles are recruited to grasp during arboreal locomotion. New electromyography data from extrinsic flexor muscles in red ruffed lemurs (Varecia rubra) walking on a simulated arboreal substrate reveal that toe flexors are activated at relatively higher levels and for longer durations than finger flexors during stance phase. This demonstrates that the extremities of primates indeed have different functional roles during arboreal locomotion, with the feet emphasizing maintenance of secure grips. When this dichotomous muscle activity pattern between the forelimbs and hind limbs is coupled with other features of primate quadrupedal locomotion, including greater hind limb weight support and the use of diagonal-sequence footfall patterns, a complex suite of biomechanical characters emerges in primates that allow for the co-option of hands toward non-locomotor roles. Early selection for limb functional differentiation in primates probably aided the evolution of fine manipulation capabilities in the hands of bipedal humans.

Empowering Women's Prenatal Communication: Does Literacy Matter?

This study was designed to evaluate the impact of an interactive computer program developed to empower prenatal communication among women with restricted literacy skills. A total of 83 women seeing 17 clinicians were randomized to a computer-based communication activation intervention (Healthy Babies Healthy Moms [HBHM]) or prenatal education (Baby Basics [BB]) prior to their prenatal visit. Visit communication was coded with the Roter Interaction Analysis System, and postvisit satisfaction was reported. Participants were on average 24 years of age and 25 weeks pregnant; 80% were African American. Two thirds scored ≤8th grade on a literacy screener. Women with literacy deficits were more verbally active, disclosed more medical and psychosocial/lifestyle information, and were rated as more dominant by coders in the HBHM group relative to their counterparts in the BB group (all ps < .05). Clinicians were less verbally dominant and more patient centered with literate HBHM relative to BB group women (p < .05); there was a similar, nonsignificant trend (p < .1) for lower literate women. Clinicians communicated less medical information and made fewer reassurance statements to lower literate women in the HBHM relative to the BB group (p < .05). There was a trend toward lower visit satisfaction for women with restricted literacy in the HBHM relative to the BB group (p < .1); no difference in satisfaction was evident for more literate women. The HBHM intervention empowered communication of all women and facilitated verbal engagement and relevant disclosure of medical and psychosocial information of women with literacy deficits. Satisfaction, however, tended to be lower for these women.

Surprising trunk rotational capabilities in chimpanzees and implications for bipedal walking proficiency in early hominins.

Human walking entails coordinated out-of-phase axial rotations of the thorax and pelvis. A long-held assumption is that this ability relies on adaptations for trunk flexibility present in humans, but not in chimpanzees, other great apes, or australopithecines. Here we use three-dimensional kinematic analyses to show that, contrary to current thinking, chimpanzees walking bipedally rotate their lumbar and thoracic regions in a manner similar to humans. This occurs despite differences in the magnitude of trunk motion, and despite morphological differences in truncal 'rigidity' between species. These results suggest that, like humans and chimpanzees, early hominins walked with upper body rotations that countered pelvic rotation. We demonstrate that even if early hominins walked with pelvic rotations 50% larger than humans, they may have accrued the energetic and mechanical benefits of out-of-phase thoracic rotations. This would have allowed early hominins to reduce work and locomotor cost, improving walking efficiency early in hominin evolution.

Three-dimensional kinematics of the pelvis and hind limbs in chimpanzee (Pan troglodytes) and human bipedal walking.

The common chimpanzee (Pan troglodytes) is a facultative biped and our closest living relative. As such, the musculoskeletal anatomies of their pelvis and hind limbs have long provided a comparative context for studies of human and fossil hominin locomotion. Yet, how the chimpanzee pelvis and hind limb actually move during bipedal walking is still not well defined. Here, we describe the three-dimensional (3-D) kinematics of the pelvis, hip, knee and ankle during bipedal walking and compare those values to humans walking at the same dimensionless and dimensional velocities. The stride-to-stride and intraspecific variations in 3-D kinematics were calculated using the adjusted coefficient of multiple correlation. Our results indicate that humans walk with a more stable pelvis than chimpanzees, especially in tilt and rotation. Both species exhibit similar magnitudes of pelvis list, but with segment motion that is opposite in phasing. In the hind limb, chimpanzees walk with a more flexed and abducted limb posture, and substantially exceed humans in the magnitude of hip rotation during a stride. The average stride-to-stride variation in joint and segment motion was greater in chimpanzees than humans, while the intraspecific variation was similar on average. These results demonstrate substantial differences between human and chimpanzee bipedal walking, in both the sagittal and non-sagittal planes. These new 3-D kinematic data are fundamental to a comprehensive understanding of the mechanics, energetics and control of chimpanzee bipedalism.

Electromyography of crural and pedal muscles in tufted capuchin monkeys (Sapajus apella): Implications for hallucal grasping behavior and first metatarsal morphology in euprimates.

A hypertrophied peroneal process of the hallucal metatarsal, as seen in prosimians, has been linked to a powerful hallucal grasp via the contraction of the peroneus longus (PL) muscle causing adduction of the big toe. Electromyography (EMG) studies of lemurs and lorises, however, have concluded that PL is not substantially recruited during small branch locomotion when powerful hallucal grasping is needed most, and have suggested that there is no link between PL activity and peroneal process size. If this is correct, then we should also observe no change in PL activity when strong hallucal grasping is required in anthropoids because they have a relatively smaller peroneal process for PL to act on. This study addresses this hypothesis by evaluating EMG of crural and pedal muscles in capuchins (Sapajus apella) walking on substrates of different diameters. During locomotion on the narrow substrate (3.1 cm) that should elicit a strong hallucal grasp, we observed an intense increased recruitment of adductor hallucis, but only sustained, rather than markedly increased, PL activity. This indicates that PL is not involved in powerful hallucal grasping in capuchins, and confirms similar findings previously documented in prosimians. We continue to reject the hypothesis that a large peroneal process is an adaptation for powerful grasping and further argue that its morphology may not be related to PL's ability to adduct the hallux at all. In addition, the morphology of the peroneal process should not be used to assess hallucal grasping performance in fossils.

Rotator cuff muscle size and the interpretation of scapular shape in primates.

Scapular shape variation among primates is widely viewed as being strongly related to locomotor differences. The relative importance of overhead forelimb elevation in the locomotor repertoire of a species, as reflected in muscular leverage for scapular rotation or in the sizes of attachment areas for muscles involved in glenohumeral elevation, has proven to be a useful organizing principle for understanding this variation. While generally successful in sorting primate scapulae into functional groups, the scapulae of some species do not entirely match predictions based on the perceived importance of forelimb elevation. A recent study has shown that scapular fossa sizes in apes are not as accurate predictors of the sizes of the muscles arising from them as has been assumed. To further explore the degree of correspondence between actual and predicted muscle size based on the perceived importance of forelimb elevation, the current study examines the relative sizes of the rotator cuff muscles in a wider sample of primate taxa using published data on muscle mass and cross-sectional area. The results do not support some of the accepted generalizations about the relative sizes of members of the rotator cuff based on measurements of the sizes of scapular fossae. For example, orthograde apes do not display enlarged supraspinatus muscles compared to pronograde monkeys. Differences in assessments of relative muscle size based on mass compared to those based on cross-sectional area suggest that poor correspondence between muscle size predicted from scapular fossa size and actual muscle size may be related to constraints on scapular form associated with muscular leverage for scapular rotation and with scapular position on the thorax.

Integrating mental health into adolescent annual visits: impact of previsit comprehensive screening on within-visit processes.

PURPOSE: To evaluate how a comprehensive, computerized, self-administered adolescent screener, the DartScreen, affects within-visit patient-doctor interactions such as data gathering, advice giving, counseling, and discussion of mental health issues. METHODS: Patient-doctor interaction was compared between visits without screening and those with the DartScreen completed before the visit. Teens, aged 15-19 years scheduled for an annual visit, were recruited at one urban and one rural pediatric primary care clinic. The doctor acted as his/her own control, first using his/her usual routine for five to six adolescent annual visits. Then, the DartScreen was introduced for five visits where at the beginning of the visit, the doctor received a summary report of the screening results. All visits were audio recorded and analyzed using the Roter interaction analysis system. Doctor and teen dialogue and topics discussed were compared between the two groups. RESULTS: Seven midcareer doctors and 72 adolescents participated; 37 visits without DartScreen and 35 with DartScreen were audio recorded. The Roter interaction analysis system defined medically related data gathering (mean, 36.8 vs. 32.7 statements; p = .03) and counseling (mean, 36.8 vs. 32.7 statements; p = .01) decreased with DartScreen; however, doctor responsiveness and engagement improved with DartScreen (mean, 4.8 vs. 5.1 statements; p = .00). Teens completing the DartScreen offered more psychosocial information (mean, 18.5 vs. 10.6 statements; p = .01), and mental health was discussed more after the DartScreen (mean, 93.7 vs. 43.5 statements; p = .03). Discussion of somatic and substance abuse topics did not change. Doctors reported that screening improved visit organization and efficiency. CONCLUSIONS: Use of the screener increased discussion of mental health but not at the expense of other adolescent health topics.

Error disclosure and family members' reactions: does the type of error really matter?

OBJECTIVE: To describe how Italian clinicians disclose medical errors with clear and shared lines of responsibility. METHODS: Thirty-eight volunteers were video-recorded in a simulated conversation while communicating a medical error to a simulated family member (SFM). They were assigned to a clear responsibility error scenario or a shared responsibility one. Simulations were coded for: mention of the term "error" and apology; communication content and affect using the Roter Interaction Analysis System. SFMs rated their willingness to have the patient continue care with the clinician. RESULTS: Clinicians referred to an error and/or apologized in 55% of the simulations. The error was disclosed more frequently in the clear responsibility scenario (p<0.02). When the "error" was explicitly mentioned, the SFM was more attentive, sad and anxious (p≤0.05) and less willing to have the patient continue care (p<0.05). Communication was more patient-centered (p<0.05) and affectively dynamic with the SFMs showing greater anxiety, sadness, attentiveness and respectfulness in the clear responsibility scenario (p<0.05). CONCLUSIONS: Disclosing errors is not a common practice in Italy. Clinicians disclose less frequently when responsibility is shared and indicative of a system failure. PRACTICE IMPLICATIONS: Training programs to improve disclosure practice considering the type of error committed should be implemented.