Molecular estimates of the divergence of placental and marsupial mammals and their broader clades (Eutheria and Metatheria, respectively) fall primarily in the Jurassic period. Supporting these estimates, Juramaia-the oldest purported eutherian-is from the early Late Jurassic (160 million years ago) of northeastern China. Sinodelphys-the oldest purported metatherian-is from the same geographic area but is 35 million years younger, from the Jehol biota. Here we report a new Jehol eutherian, Ambolestes zhoui, with a nearly complete skeleton that preserves anatomical details that are unknown from contemporaneous mammals, including the ectotympanic and hyoid apparatus. This new fossil demonstrates that Sinodelphys is a eutherian, and that postcranial differences between Sinodelphys and the Jehol eutherian Eomaia-previously thought to indicate separate invasions of a scansorial niche by eutherians and metatherians-are instead variations among the early members of the placental lineage. The oldest known metatherians are now not from eastern Asia but are 110 million years old from western North America, which produces a 50-million-year ghost lineage for Metatheria.

Background: One-half of all orthopedic surgeries require bone grafting for successful outcomes in fusions, reconstructive procedures, and the treatment of osseous defects resulting from trauma, tumor, infection, or congenital deformity. Autologous bone grafts are taken from the patient's own body and remain the "gold standard" graft choice but are limited in supply and impart significant patient morbidity. Xenograft bone is an attractive alternative from donors with controlled biology, in large supply and at a theoretically lower cost. Clinical results with xenograft bone for orthopedic applications have been mixed in the limited clinical trials published. Methods: In the current review, we introduce fundamental principles of bone grafting, systematically review all orthopedic clinical studies reporting outcomes on patients transplanted with xenograft bone, and we present our own clinical results from patients grafted with bovine bone in foot and ankle reconstructive procedures. Results: Thirty-one clinical studies were identified for review and the majority (47%) were from spine surgery literature. Favorable results were reported in 44% of studies while 47% of studies reported poor outcomes and discouraged use of xenograft bone products. In our own clinical series, xenograft failed to integrate with host bone in 58% of cases and persistent pain was reported in 83% of cases. Conclusions: This is the first systematic review of clinical results reported after bone xenotransplantation for orthopaedic surgery applications. Current literature does not support the use of xenograft bone products and our institution's results are consistent with this conclusion. Our laboratory has reported promising pre-clinical results with a xenograft product derived from porcine cancellous bone, but additional testing is required before considering clinical translation.

Neuralgic amyotrophy (NA), also referred to as idiopathic brachial plexitis and Parsonage‐Turner syndrome, is a peripheral nerve disorder characterized by acute severe shoulder pain followed by progressive upper limb weakness and muscle atrophy. While NA is incompletely understood and often difficult to diagnose, early recognition may prevent unnecessary tests and interventions and, in some situations, allow for prompt treatment, which can potentially minimize adverse long‐term sequalae. High‐resolution ultrasound (HRUS) has become a valuable tool in the diagnosis and evaluation of NA. Pathologic HRUS findings can be grouped into four categories: nerve swelling, swelling with incomplete constriction, swelling with complete constriction, and fascicular entwinement, which may represent a continuum of pathologic processes. Certain ultrasound findings may help predict the likelihood of spontaneous recovery with conservative management versus the need for surgical intervention. We recommend relying heavily on history and physical examination to determine which nerves are clinically affected and should therefore be assessed by HRUS. The nerves most frequently affected by NA are the suprascapular, long thoracic, median and anterior interosseous nerve (AIN) branch, radial and posterior interosseous nerve (PIN) branch, axillary, spinal accessory, and musculocutaneous. When distal upper limb nerves are affected (AIN, PIN, superficial radial nerve), the lesion is almost always located in their respective fascicles within the parent nerve, proximal to its branching point. The purpose of this review is to describe a reproducible, standardized, ultrasonographic approach for evaluating suspected NA, and to share reliable techniques and clinical considerations when imaging commonly affected nerves.

Background: Resident cosmetic clinics (RCCs) are the training modality of choice among both residents and faculty and are a mainstay at most residency programs. 1 – 4 Despite this, knowledge of RCCs among plastic surgery consumers remains untested. We hypothesize that the public would be aware of and receptive to RCCs. Methods: Participants with prior cosmetic procedures or interest in future cosmetic procedures were recruited using Amazon Mechanical Turk and asked to complete a survey in September 2020. First, prior awareness of RCCs was assessed. After a brief description of RCCs, perceptions of safety and preferences for care were assessed. Results: After screening for quality, 815 responses were included. Forty-five percent of consumers were aware of RCCs. Seventy-six percent of consumers believed that RCCs were just as safe as attending clinics and 65% were comfortable receiving care from fourth-year residents or higher. Belief in RCC safety was associated with 4.8 times higher odds of feeling comfortable receiving care at an RCC [95% confidence interval (3.3–7.1), P < 0.001]. When given a hypothetical choice between residents and attendings in two scenarios, 46% of consumers chose residents for abdominoplasty and 60% chose residents for Botox injections. Belief in RCC safety was associated with choosing a resident or being indifferent in both scenarios. Conclusions: Consumer preference regarding RCCs has largely been untested. This study shows that belief in RCC safety influences consumers’ perceived comfort with receiving care at an RCC. This knowledge can help guide RCC practice and maximize learning opportunities for surgeons-in-training.