Surgeon Performance as a Predictor for Patient-Reported Outcomes After Arthroscopic Partial Meniscectomy.

Background: Surgeon performance has been investigated as a factor affecting patient outcomes after orthopaedic procedures to improve transparency between patients and providers. Purpose/Hypothesis: The purpose of this study was to identify whether surgeon performance influenced patient-reported outcomes (PROMs) 1 year after arthroscopic partial meniscectomy (APM). It was hypothesized that there would be no significant difference in PROMs between patients who underwent APM from various surgeons. Study Design: Case-control study; Level of evidence, 3. Methods: A prospective cohort of 794 patients who underwent APM between 2018 and 2019 were included in the analysis. A total of 34 surgeons from a large multicenter health care center were included. Three multivariable models were built to determine whether the surgeon-among demographic and meniscal pathology factors-was a significant variable for predicting the Knee injury and Osteoarthritis Outcome Score (KOOS)-Pain subscale, the Patient Acceptable Symptom State (PASS), and a 10-point improvement in the KOOS-Pain at 1 year after APM. Likelihood ratio (LR) tests were used to determine the significance of the surgeon variable in the models. Results: The 794 patients were identified from the multicenter hospital system. The baseline KOOS-Pain score was a significant predictor of outcome in the 1-year KOOS-Pain model (odds ratio [OR], 2.1 [95% CI, 1.77-2.48]; P < .001), the KOOS-Pain 10-point improvement model (OR, 0.57 [95% CI, 0.44-0.73), and the 1-year PASS model (OR, 1.42 [95% CI, 1.15-1.76]; P = .002) among articular cartilage pathology (bipolar medial cartilage) and patient-factor variables, including body mass index, Veterans RAND 12-Item Health Survey-Mental Component Score, and Area Deprivation Index. The individual surgeon significantly impacted outcomes in the 1-year KOOS-Pain mixed model in the LR test (P = .004). Conclusion: Patient factors and characteristics are better predictors for patient outcomes 1 year after APM than surgeon characteristics, specifically baseline KOOS-Pain, although an individual surgeon influenced the 1-Year KOOS-Pain mixed model in the LR test. This finding has key clinical implications; surgeons who wish to improve patient outcomes after APM should focus on improving patient selection rather than improving the surgical technique. Future research is needed to determine whether surgeon variability has an impact on longer-term patient outcomes.

Rhesus monkeys show greater habituation to repeated computer-generated images than do orangutans.

Humans and several other species of animals have demonstrated the ability to use familiarity to recognize that they have seen images before. In prior experiments, orangutans failed to show use of familiarity in memory tasks, even when other solutions were not available. We tested for evidence of habituation, a decreased response to repeated stimuli, as a behavioral indicator that repeated images were familiar to subjects. Monkeys and orangutans selected the smallest target out of four while computerized images were presented as distractors. Latency to complete the target-finding task was compared between conditions in which the distractor image was a familiar, repeating image, a novel, never-before-seen image, or no distractor was present. Rhesus macaques showed significant habituation, and significantly more habituation than orangutans, in each of four experiments. Orangutans showed statistically reliable habituation in only one of the four experiments. These results are consistent with previous research in which orangutans failed to demonstrate familiarity. Because we expect that familiarity and habituation are evolutionarily ancient memory processes, we struggle to explain these surprising, but consistent findings. Future research is needed to determine why orangutans respond to computerized images in this peculiar way.

No evidence of real-world equivalence in chickens (Gallus gallus domesticus) categorizing visually diverse images of natural stimuli presented on LCD monitors.

Category learning is often tested with similar images that have no significance outside of the experiment for the subjects. By contrast, in nature animals often need to generalize a behavioral response like "eat" across visually distinct stimuli, such as spiders and seeds. Forming functional categories like "food" and "predator" may require conceptual rather than purely perceptual generalization. We trained free-range chickens to classify images assigned to one of four categories based on putative functional significance: inanimate objects, predators, food, and non-competing vertebrates. Images were visually diverse within each category, discouraging classification by perceptual similarity alone. In Experiment 1, chickens classified 80 images into four categories. Chickens then generalized to 80 new exemplars in each of three successive generalization tests. In Experiment 2, chickens saw new types of images to test whether their generalization was perceptual or functional. For example, chickens saw images of skunks for the predator category after training with images of hawks and snakes. Chickens used the "predator" response with these new images for both predators and non-threatening vertebrates, but not for objects or food, and did not successfully generalize any category other than predator. In Experiment 3, chickens categorized fractals as "food," and three of four chickens categorized a range of vertebrates they had not previously encountered as "predators," suggesting that chickens did not see the images as representing real world objects and animals. These results highlight constraints on the use of computer-generated images to assess categorization of natural stimuli in chickens.

Six adult male rhesus monkeys did not learn from the choices of a conspecific shown in videos.

There is substantial evidence of group-specific behaviors in wild animals that are thought to be socially transmitted. Yet experimental studies with monkeys have reported conflicting evidence on the extent to which monkeys learn by observing their conspecifics. In this study, we tested the feasibility of using pre-recorded video demonstrations to investigate social learning from conspecifics in rhesus monkeys. With training, monkeys gradually learned to respond correctly following videos of a demonstrator, however, follow-up experiments revealed that this was not due to learning from the demonstrator monkey. In generalization tests with videos that were horizontally reversed, monkeys continued responding to the location they had associated with each video, rather than matching the new choice location shown in the mirrored video. When the task was changed to make location irrelevant, such that monkeys could choose correctly only by selecting the same image selected by the demonstrator in the video, observer monkeys did not exceed chance in 12,000 training trials. Because monkeys readily learn to follow nonsocial visual cues presented on a monitor to guide image choice, their inability to learn from a demonstrator here indicates substantial limitations in the capacity for social learning from videos. Furthermore, these findings encourage deeper consideration of what monkeys perceive when presented with video stimuli on computer screens.

Rhesus monkeys manipulate mental images.

Humans form mental images and manipulate them in ways that mirror physical transformations of objects. Studies of nonhuman animals will inform our understanding of the evolution and distribution among species of mental imagery. Across three experiments, we found mostly converging evidence that rhesus monkeys formed and rotated mental images. In Experiment 1, monkeys discriminated rotations of sample images from mirror images, and showed longer response latencies with greater rotation as is characteristic of human mental rotation. In Experiment 2 monkeys used a rotation cue that indicated how far to mentally rotate sample images before tests, indicating a precision of better than 30° in discriminating rotations. Experiment 3 yielded mixed evidence on whether the rotation cue shortened decision times as has been found in humans. These results show that rhesus monkeys manipulate mental images.

Control of Attention in Rhesus Monkeys Measured Using a Flanker Task.

At least three processes determine whether information we encounter is attended to or ignored. First, attentional capture occurs when attention is drawn automatically by "bottom up" processes, to distinctive, salient, rewarding, or unexpected stimuli when they enter our sensory field. Second, "top down" attentional control can direct cognitive processing towards goal-relevant targets. Third, selection history, operates through repeated exposure to a stimulus, particularly when associated with reward. Attentional control is measured using tasks that require subjects to selectively attend to goal-relevant stimuli in the face of distractions. In the Eriksen flanker task, human participants report which direction a centrally placed arrow is facing, while ignoring "flanking" arrows that may point in the opposite direction. Attentional control is evident to the extent that performance reflects only the direction of the central arrow. We describe four experiments in which we systematically assessed attentional control in rhesus monkeys using a flanker task. In Experiment 1, monkeys responded according to the identity of a central target, and accuracy and latency varied systematically with manipulations of flanking stimuli, validating our adaptation of the Eriksen flanker task. We then tested for converging evidence of attentional control across three experiments in which flanker performance was modulated by the distance separating targets from flankers (Experiment 2), luminance differences (Experiment 3), and differences in associative value (Experiment 4). The approach described is a new and reliable measure of attentional control in rhesus monkeys that can be applied to a wide range of situations with freely behaving animals.

No clinically meaningful difference in 1-year patient-reported outcomes among major approaches for primary total hip arthroplasty.

BACKGROUND: Debate continues around the most effective surgical approach for primary total hip arthroplasty (THA). This study's purpose was to compare 1-year patient-reported outcome measures (PROMs) of patients who underwent direct anterior (DA), transgluteal anterolateral (AL)/direct lateral (DL), and posterolateral (PL) approaches. METHODS: A prospective consecutive series of primary THA for osteoarthritis (n = 2390) were performed at 5 sites within a single institution with standardised care pathways (20 surgeons). Patients were categorised by approach: DA (n = 913; 38%), AL/DL (n = 505; 21%), or PL (n = 972; 41%). Primary outcomes were pain, function, and activity assessed by 1-year postoperative PROMs. Multivariable regression modeling was used to control for differences among the groups. Wald tests were performed to test the significance of select patient factors and simultaneous 95% confidence intervals were constructed. RESULTS: At 1-year postoperative, PROMs were successfully collected from 1842 (77.1%) patients. Approach was a statistically significant factor for 1-year HOOS pain (p = 0.002). Approach was not a significant factor for 1-year HOOS-PS (p = 0.16) or 1-year UCLA activity (p = 0.382). Pairwise comparisons showed no significant difference in 1-year HOOS pain scores between DA and PL approach (p > 0.05). AL/DL approach had lower (worse) pain scores than DA or PL approaches with differences in adjusted median score of 3.47 and 2.43, respectively (p < 0.05). CONCLUSIONS: Patients receiving the AL/DL approach had a small statistical difference in pain scores at 1 year, but no clinically meaningful differences in pain, activity, or function exist at 1-year postoperative.

Interaction of memory systems is controlled by context in both food-storing and non-storing birds.

Animals and humans have multiple memory systems. While both black-capped chickadees (Poecile atricapillus) and dark-eyed juncos (Junco hyemalis) are under selective pressure to remember reliable long-term spatial locations (habit memory), chickadees must additionally quickly form and rapidly update spatial memory for unique cache sites (one-trial memory). We conducted a series of three experiments in which we assessed the degree to which habit and one-trial memory were expressed in both species as a function of training context. In Experiment 1, birds failed to demonstrate habits on probe trials after being trained in the context of a biased Match-to-Sample task in which the same high-frequency target was always correct. In Experiment 2, habit strongly controlled performance when habits were learned as Discriminations, defining a specific training context. In Experiment 3, context no longer defined when to express habits and habit and one-trial memory competed for control of behavior. Across all experiments, birds preferentially used the memory system at test that was consistent with the context in which it was acquired. Although the memory adaptations that allow chickadees to successfully recover cached food might predispose them to favor one-trial memory, we found no species differences in the weighting of habit and one-trial memory. In the experiments here, context was a powerful factor controlling the interaction of memory systems.

Greater dependence on working memory and restricted familiarity in orangutans compared with rhesus monkeys.

The prefrontal cortex is larger than would be predicted by body size or visual cortex volume in great apes compared with monkeys. Because prefrontal cortex is critical for working memory, we hypothesized that recognition memory tests would engage working memory in orangutans more robustly than in rhesus monkeys. In contrast to working memory, the familiarity response that results from repetition of an image is less cognitively taxing and has been associated with nonfrontal brain regions. Across three experiments, we observed a striking species difference in the control of behavior by these two types of memory. First, we found that recognition memory performance in orangutans was controlled by working memory under conditions in which this memory system plays little role in rhesus monkeys. Second, we found that unlike the case in monkeys, familiarity was not involved in recognition memory performance in orangutans, shown by differences with monkeys across three different measures. Memory in orangutans was not improved by use of novel images, was always impaired by a concurrent cognitive load, and orangutans did not accurately identify images seen minutes ago. These results are surprising and puzzling, but do support the view that prefrontal expansion in great apes favored working memory. At least in orangutans, increased dependence on working memory may come at a cost in terms of the availability of familiarity.

Animal consciousness: Should a new behavioral correlate in monkeys persuade agnostics?

After human subjects learn to look away from visible cues, their attention can still be captured by cues so brief that they cause no conscious perception. A new study has found evidence that this behavior also occurs in monkeys. Is this further evidence for consciousness in a nonhuman animal?

Rhesus monkeys (Macaca mulatta) monitor evolving decisions to control adaptive information seeking.

Adaptive decision making in humans depends on feedback between monitoring, which assesses mental states, and control, by which cognitive processes are modified. We investigated the extent to which monitoring and control interact iteratively in monkeys. Monkeys classified images as birds, fish, flowers, or people. At the beginning of each trial, to-be-classified images were not visible. Monkeys touched the image area to incrementally brighten the image, referred to as the brighten response. The amount by which brightness increased with each brighten response was unpredictable, and the monkeys could choose to classify the images at any time during a trial. We hypothesized that if monkeys monitored the status of their classification decision then they would seek information depending on the amount of information available. In Experiment 1, monkeys rarely used the brighten response when images were bright initially, and they used the brighten response more when earlier uses in a given trial yielded smaller amounts of information. In Experiment 2, monkeys made more brighten responses when the presented image did not belong in any of the trained categories, suggesting monkeys were sensitive to the fact that they could not reach a classification decision despite the image brightening. In Experiment 3, we found that the probability that monkeys used the brighten response correlated with their ability to correctly classify when the brighten response was not available. These findings add to the literature documenting the metacognitive skills of nonhuman primates by demonstrating an iterative feedback loop between cognitive monitoring and cognitive control that allows for adaptive information-seeking behavior.

Designer receptor inhibition suggests mechanism for monkey Theory of Mind.

Theory of Mind (ToM) is a critical component of human social cognition that has not been found reliably in other primates, especially monkeys. Hayashi et al. (Cell Reports, 30, 4433-4444, 2020) used newly developed behavioral techniques to detect evidence for ToM in Japanese macaque monkeys and employed sophisticated neurobiological manipulations to implicate the medial prefrontal cortex is this capacity.

Preserved visual memory and relational cognition performance in monkeys with selective hippocampal lesions.

The theory that the hippocampus is critical for visual memory and relational cognition has been challenged by discovery of more spared hippocampal tissue than previously reported in H.M., previously unreported extra-hippocampal damage in developmental amnesiacs, and findings that the hippocampus is unnecessary for object-in-context memory in monkeys. These challenges highlight the need for causal tests of hippocampal function in nonhuman primate models. Here, we tested rhesus monkeys on a battery of cognitive tasks including transitive inference, temporal order memory, shape recall, source memory, and image recognition. Contrary to predictions, we observed no robust impairments in memory or relational cognition either within- or between-groups following hippocampal damage. These results caution against over-generalizing from human correlational studies or rodent experimental studies, compel a new generation of nonhuman primate studies, and indicate that we should reassess the relative contributions of the hippocampus proper compared to other regions in visual memory and relational cognition.

Cognitive control of working memory but not familiarity in rhesus monkeys (Macaca mulatta).

Directed forgetting paradigms assess cognitive control by determining whether memory accuracy is superior in trials on which subjects were instructed to remember compared with accuracy in trials on which they were instructed to forget. We used a directed forgetting paradigm to compare the extent to which working memory and familiarity are subject to rehearsal-like cognitive control in rhesus monkeys. Monkeys studied a sample image, then saw one of two distinctive cues during a retention interval. The remember cue typically predicted a four-choice match to sample test, for which memory of the sample was critical. The forget cue typically predicted one of five perceptual discrimination tests, matched for accuracy to the memory tests, for which memory of the sample was irrelevant. On rare probe trials, the test type other than the type typically predicted by the cue was presented. When cognitive control of memory was possible, accuracy should have been higher on memory tests following the remember cue than on those following the forget cue. We found that accuracy was higher following the remember cue under conditions that favored working memory (small image set) but was not higher under conditions that favored matching on the basis of relative familiarity (large image set). Working memory, but not familiarity, is subject to cognitive control in rhesus monkeys.

Associative models fail to characterize transitive inference performance in rhesus monkeys (Macaca mulatta).

It has been suggested that non-verbal transitive inference (if A > B and B > C, then A > C) can be accounted for by associative models. However, little is known about the applicability of such models to primate data. In Experiment 1, we tested the fit of two associative models to primate data from both sequential training, in which the training pairs were presented in a backward order, and simultaneous training, in which all training pairs are presented intermixed from the beginning. We found that the models provided an equally poor fit for both sequential and simultaneous training presentations, contrary to the case with data from pigeons. The models were also unable to predict the robust symbolic distance effects characteristic of primate transitive choices. In Experiment 2, we used the models to fit a list-linking design in which two seven-item transitive lists were first trained independently (A > B…. > F > G and H > I …. > M > N) then combined via a linking pair (G+ H-) into a single, 14-item list. The model produced accurate predictions for between-list pairs, but did not predict transitive responses for within-list pairs from list 2. Overall, our results support research indicating that associative strength does not adequately account for the behavior of primates in transitive inference tasks. The results also suggest that transitive choices may result from different processes, or different weighting of multiple processes, across species.

Explicit memory and cognition in monkeys.

Taxonomies of human memory, influenced heavily by Endel Tulving, make a fundamental distinction between explicit and implicit memory. Humans are aware of explicit memories, whereas implicit memories control behavior even though we are not aware of them. Efforts to understand the evolution of memory, and to use nonhuman animals to model human memory, will be facilitated by better understanding the extent to which this critical distinction exists in nonhuman animals. Work with metacognition paradigms in the past 20 years has produced a strong case for the existence of explicit memory in nonhuman primates and possibly other nonhuman animals. Clear dissociations of explicit and implicit memory by metacognition have yet to be demonstrated in nonhumans, although dissociations between memory systems by other behavioral techniques, and by brain manipulations, suggest that the explicit-implicit distinction applies to nonhumans. Neurobehavioral studies of metamemory are beginning to identify neural substrates for memory monitoring in the frontal cortex of monkeys. We have strong evidence that at least some memory systems are explicit in rhesus monkeys, but we need to learn more about the distribution of explicit processes across cognitive systems within monkeys, and across species.

Cephalomedullary nailing versus sliding hip screws for Intertrochanteric and basicervical hip fractures: a propensity-matched study of short-term outcomes in over 17,000 patients.

BACKGROUND: Hip fractures are associated with poor mortality and morbidity outcomes. Controversy exists over what the preferred treatment is between sliding hips screws (SHSs) and cephalomedullary nails (CMNs) for stable intertrochanteric (IT) and basicervical (BC) hip fractures. The purpose of this study was to compare early postoperative outcomes and complications in patients treated with SHS to those treated with CMN in IT and BC hip fractures. METHODS: We used the National Surgical Quality Improvement Program database to identify IT and BC hip fractures, excluding subtrochanteric hip fractures treated with a SHS and CMN for 2008 to 2016. After propensity score matching, there were 8505 patients in the SHS cohort and 8505 in the CMN cohort. Propensity score-adjusted multivariate regression models assed SHS as an independent risk factor for the following 30-day outcomes: mortality, postoperative major and minor complications, discharge disposition, readmission and reoperation, length of hospital stay (LOS), and operative time. RESULTS: No difference in mortality was encountered between SHS and CMN (p = 0.440). Compared to CMN, the SHS cohort had an 11.6% decreased likelihood of a minor complication (p < 0.001); however, no difference was found between CMN and SHS for major complications (p = 0.117). SHS patients were less likely to have transfusion (p < 0.001), DVT (p = 0.007), and MI (0.024). SHS patients were 12.5% more likely to go home (p = 0.002). No association was discovered between being treated with a SHS and reoperation (p = 0.449) and readmission (p = 0.588). SHS patients had almost a quarter of a day longer LOS (p = 0.041). Patients treated with SHS had a statistically significant (p < 0.001), but clinically irrelevant 2-min longer procedure. LEVEL OF EVIDENCE: III.

Venous thromboembolism rates remained unchanged in operative lower extremity orthopaedic trauma patients from 2008 to 2016.

BACKGROUND: Venous thromboembolism (VTE) is a serious complication that contributes to morbidity, mortality, and healthcare costs during the surgical care of patient with lower extremity fractures. Despite this, few recommendations on the topic exist and the literature on VTE incidence is incomplete. Therefore, this study will attempt to estimate annual incidence and trends in 30-day thrombotic events and mortality for the following fractures: (1) hip, (2) femur, (3) patella, (4) tibia and/or fibula, and (5) ankle. METHODS: We identified 120,521 operative lower extremity orthopaedic trauma patients from 2008 to 2016 using the American College of Surgeons National Surgical Quality Improvement Program (NSQIP) database. To evaluate the relationship between the year in which surgery was performed and comorbidities and demographic information bivariate analysis was performed. Bivariate analysis was also performed for the outcomes of interest and year in which the surgery was performed to assess for change. Additionally, bimodal multivariate logistic regression models for hip, femur, and ankle fractures were built, comparing the years 2009 to 2016 using 2008 as a baseline. RESULTS: Overall incidence for VTE over the study period was 1.7% for hip fractures, 2.4% for femur fractures, 0.9% for patella fractures, 1.1% in tibia and/or fibula fractures, and 0.6% in ankle fractures. Over the study period VTE incidence saw a significant decrease (p < 0.05) in hip and femur fractures, but not for patella, tibia and/or fibula, and ankle fractures. After adjusting for confounding factors with multivariate analysis, the change in hip and femur fractures was no longer significant, while no significant decrease was again found for ankle fractures (p > 0.05). CONCLUSION: Our study demonstrates that VTE rates have remained unchanged in operative lower extremity orthopaedic trauma from 2008 to 2016. This highlights the need for higher quality evidence on this important topic in orthopaedic trauma, including a reevaluation on the necessity of thromboprophylaxis guidelines. LEVEL OF EVIDENCE: III.