Large-Scale Validation of the Paddling Pool Task in the Clockmaze for Studying Hippocampus-Based Spatial Cognition in Mice.

Rationally designed behavioral tests are important tools to assess the function of specific brain regions. The hippocampus is a crucial neural substrate for spatial cognition, and many studies have linked hippocampal dysfunction with defects on spatial learning and memory in neurological conditions ranging from Alzheimer's disease to autoimmune syndromes, such as neuropsychiatric lupus. While our understanding of hippocampal function, from the molecular to the system levels, has increased dramatically over the last decades, this effort has not yet translated into efficacious therapies for cognitive impairment. We think that the availability of highly validated behavioral paradigms to measure cognition in mouse models is likely to enhance the potential success of preclinical therapeutic modalities. Here, we present an extensive study of the paddling pool task (PPT), first reported by Deacon and Rawlins, in which mice learn to escape from shallow water through a peripheral exit in a circular arena dubbed the clockmaze. We show that the PPT provides highly reliable results when assaying spatial cognition in C57/BL6 mice (120 males, 40 females) and BALB/c mice (40 males, 90 females). Additionally, we develop a robust algorithm for the assessment of escape strategies with clearly quantifiable readouts, enabling fine-granular phenotyping. Notably, the use of spatial strategy increases linearly across trials in the PPT. In a separate cohort of mice, we apply muscimol injections to silence the dorsal CA1 region of the hippocampus and show that the use of the spatial strategy in the PPT relies on the integrity of the dorsal hippocampus. Additionally, we compare directly the PPT and the Morris water maze (MWM) task in C57/BL6 mice (20 males, 20 females) and BALB/c mice (20 males, 20 females) and we find that the PPT induces significantly lower anxiety, exhaustion and hypothermia than the MWM. We conclude that the PPT provides a robust assessment of spatial cognition in mice, which can be applied in conjunction with other tests, to facilitate hypothesis testing and drug development to combat cognitive impairment.

Is interposition arthroplasty a viable option for treatment of moderate to severe hallux rigidus? - A systematic review and meta-analysis.

INTRODUCTION: When conservative therapy for hallux rigidus fails, surgical options such as arthrodesis and interposition arthroplasty can be considered. Although arthrodesis of MTP joint is the gold standard treatment. However patients desiring MTP joint movement may opt for either interposition arthroplasty or implant arthroplasty to avoid the movement restrictions of arthrodesis. The purpose of this systematic review was to investigate clinical outcomes and complications following interposition arthroplasty for moderate to severe hallux rigidus, for patietns who would prefer to maintain range of motion in the MTP joint. METHODS: A systematic search on MEDLINE, EMBASE and Cochrane library database was performed during February 2018. Demographics, surgical techniques, clinical outcomes, radiological outcomes and complications were recorded from each included study. Pooled statistics performed for variables with homogenous data across the studies. A linear regression model used to compare the clinical outcomes between autogenous vs allogenous material interposition arthroplasty. RESULTS: Fifteen articles were included in the systematic review. Mean AOFAS scores improved from preoperative 41.35 to postoperative 83.17. Mean pain, function, and alignment score improved from preoperative values of 14.9, 24.9, and 10 to postoperative values of 33.3, 35.8, and 14.5. Mean dorsiflexion increased from 21.27° (5-30) to 42.03° (25-71). Mean ROM improved from 21.06° to 46.43°. Joint space increased from 0.8mm to 2.5mm. The most common postoperative complications included metatarsalgia (13.9%), loss of ground contact (9.7%), osteonecrosis (5.4%), great toe weakness (4.8%), hypoesthesia (4.2%), decreased push off power (4.2%), and callous formation (4.2%). CONCLUSION: Interposition arthroplasty is an effective treatment option with acceptable clinical outcomes in patients with moderate-severe hallux rigidus who prefer to maintain range of motion and accept the risk of future complications. LEVEL OF EVIDENCE: IV.

Associations between season and surgical site infections in orthopaedic foot and ankle surgery.

BACKGROUND: Surgical site infections (SSI) in orthopaedic surgery are common nosocomial complications that contribute significantly to patient morbidity and increased healthcare costs. While past studies support an increase in the incidence of SSI during the summer months in orthopaedic spine surgery and joint arthroplasty, there has not been any study examining the association between season and SSI in the setting of orthopaedic foot and ankle surgery. METHODS: A retrospective analysis of data from the American College of Surgeons National Surgical Quality Improvement Program (NSQIP) database from 2011-2015 was conducted. 17,939 patients who received at least one of 218 CPT codes specific to orthopaedic foot and ankle surgery were identfied from the NSQIP database. Descriptive statistics of patient demographics, comorbidities, and complications were stratified by quarter of admission. RESULTS: Of the 17,939 patients, there were 4995 in the 1st quarter (27.8%), 4078 in the 2nd quarter (22.7%), 4333 in the 3rd quarter (24.2%), and 4533 in the 4th quarter (25.3%). The overall rate of surgical complications was 2.3%. The highest incidence of surgical complications was during the summer at 2.7% and the lowest was during the fall at 2.1% (p=0.338). The summer months also demonstrated the highest incidence of medical complications at 5.9% (p=0.524). There were significantly more women undergoing surgery in the winter and summer months (p=0.028). CONCLUSION: The surgical site infection rate in the setting of orthopaedic foot and ankle surgery was higher, although not significantly, in the summer months. LEVEL OF EVIDENCE: Level III retrospective.