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.

Postoperative atrial fibrillation in paraesophageal hernia repair: can it be prevented?

Acute ischemic thromboembolic stroke is one of the most feared complications of atrial fibrillation (AF), and the risk increases with higher CHA2DS2-VASc scores. Postoperative atrial fibrillation (POAF) is common after noncardiac surgery, particularly after thoracic surgery, and can result in significant morbidity and mortality. We report the case of an 85-year-old female with a history of untreated hypertension (HTN) and no prior history of AF, who presented 5 days after an elective repair of a paraesophageal hernia with recurrence of a large type III paraesophageal hiatal hernia, AF, and subsequent acute thromboembolic ischemic stroke. Patient's AF resolved shortly after treatment with calcium channel blocker. The risk of stroke is high in patients who develop AF and a period of 48 h after onset of AF is usually considered safe as the risk of stroke is low in this time period. However, this may not be the case during the perioperative period and preventive measures such as preoperative calcium channel blocker could be considered. Our case highlights that acute ischemic thromboembolic stroke might develop earlier tha 48 h after onset of POAF in patients undergoing paraesophageal hernia repair. Initiation of a calcium channel blocker should be considered during preoperative evaluation for patients undergoing paraesophageal hernia repairs, especially in those with untreated HTN.