Collaborative Team Training in Virtual Reality is Superior to Individual Learning For Performing Complex Open Surgery: A Randomized Controlled Trial.

OBJECTIVE: To assess whether multiplayer immersive Virtual Reality (iVR) training was superior to single-player training for the acquisition of both technical and nontechnical skills in learning complex surgery. BACKGROUND: Superior teamwork in the operating room (OR) is associated with improved technical performance and clinical outcomes. iVR can successfully train OR staff individually; however, iVR team training has yet to be investigated. METHODS: Forty participants were randomized to individual or team iVR training. Individually trained participants practiced alongside virtual avatar counterparts, whereas teams trained live in pairs. Both groups underwent 5 iVR training sessions over 6 weeks. Subsequently, they completed a real-life assessment in which they performed anterior approach total hip arthroplasty surgery on a high-fidelity model with real equipment in a simulated OR. Teams performed together, and individually trained participants were randomly paired up. Videos were marked by 2 blinded assessors recording the 'Non-Operative Technical Skills for Surgeons, Oxford NOn-TECHnical Skills II and Scrub Practitioners' List of Intraoperative Non-Technical Skills' scores. Secondary outcomes were procedure duration and the number of technical errors. RESULTS: Teams outperformed individually trained participants for nontechnical skills in the real-world assessment (Non-Operative Technical Skills for Surgeons: 13.1±1.5 vs 10.6±1.6, P = 0.002, Non-TECHnical Skills II score: 51.7 ± 5.5 vs 42.3 ± 5.6, P = 0.001 and Scrub Practitioners' List of Intraoperative Non-Technical Skills: 10 ± 1.2 vs 7.9 ± 1.6, P = 0.004). They completed the assessment 33% faster (28.2 minutes ± 5.5 vs 41.8 ± 8.9, P < 0.001), and made fewer than half the number of technical errors (10.4 ± 6.1 vs 22.6 ± 5.4, P < 0.001). CONCLUSIONS: Multiplayer training leads to faster surgery with fewer technical errors and the development of superior nontechnical skills.

Editorial Commentary: In Patients With Hip-Spine Syndrome, a Single Simple Solution May Not Apply: Occam's Razor Becomes Blunt.

The importance of hip-spine syndrome in a nonarthritic population, in which patients present with coexisting symptoms in both the hip and lumbar spine, is becoming more clear. Several studies have shown inferior outcomes in patients undergoing treatment for femoral acetabular impingement syndrome with coexisting spinal symptoms. The most important factor when treating HSS patients is understanding each patient's pathology. A history and physical examination with provocative tests for spinal and hip pathology often provide the answer. Routine standing and seated lateral radiographs are required to assess spinopelvic mobility. If the cause of pain is unclear, diagnostic intra-articular hip injections with local anesthetic and further imaging of the lumbar spine are recommended. In patients with degenerative spine disease with neural impingement, these symptoms may persist after hip arthroscopy, particularly if not improved by intra-articular injections. Patients should be appropriately counseled. If hip symptoms predominate, treatment of femoroacetabular impingement syndrome results in improved outcomes, even with coexisting neural impingement. If spine symptoms predominate, referral to an appropriate specialist may be required. In patients with HSS, Occam's razor becomes blunt; thus, a single simple solution may not apply, and we may need to consider treating each pathology separately.

Complications and early recovery following hip hemiarthroplasty through the direct anterior approach: a systematic review and meta-analysis.

PURPOSE: Minimizing complications is an important focus in hip hemiarthroplasty (HHA) for femoral neck fracture (FNF) patients given the associated high morbidity and mortality rates. This systematic review and meta-analysis aimed to compare the clinical and functional outcomes associated with the direct anterior approach (DAA) compared to other surgical approaches used for HHA. METHODS: Studies evaluating HHA-treated FNFs using the DAA were compared through meta-analysis to all other surgical approaches combined and as distinct subgroups. Outcomes included overall complication rate, mortality rate, dislocation rate, reoperation rate, periprosthetic fracture rate, infection rate, length of stay (LOS), mobility, perioperative blood loss, operative time, and postoperative pain. RESULTS: Nineteen studies met the inclusion criteria, totaling 2,018 HHAs. DAA significantly reduced the overall complication rate (odds ratio (OR) = 0.73, 95% confidence interval (CI) 0.57 to 0.94, p = 0.01), dislocation rate (OR = 0.34, 95% CI 0.15 to 0.77, p = 0.01), and LOS (mean difference (MD) = -1.31 days, 95% CI - 2.12 to - 0.50, p = 0.002). Findings from studies that were not appropriate for meta-analysis were qualitatively summarized and suggested improved mobility and reduced postoperative pain with the DAA. Significant differences were not detected in any of the remaining outcomes. CONCLUSION: The DAA HHA appears to be safer, reduces hospital stay, and may improve early functional recovery. This article supports the DAA HHA as a safe option for the management of displaced intracapsular FNFs.

Predictors of Pediatric Anterior Cruciate Ligament Injury: The Influence of Steep Lateral Posterior Tibial Slope and Its Relationship to the Lateral Meniscus.

PURPOSE: To examine the relationship between posterior tibial slope and lateral meniscal bone angle (LMBA) on anterior cruciate ligament (ACL) tear risk in a pediatric population. METHODS: In this case-control study, non-contact ACL-injured pediatric patients with no significant lateral meniscal lesions were matched by age and sex in a 1:1 ratio to a group of radiologically normal controls. Knee magnetic resonance imaging (MRI) studies were analyzed by 3 independent, blinded observers measuring the medial posterior tibial slope (MTS), lateral posterior tibial slope (LTS), and LMBA. Sagittal slope asymmetry was calculated as the absolute difference in degrees between slopes, and the relationship between LMBA and LTS was calculated as a ratio. Binary logistic regressions identified independent predictors of ACL injury. Receiver operator characteristics were performed to determine predictive accuracy. RESULTS: 20 study patients were compared with 20 sex- and age-matched controls (age 14.8 ± 2.42, mean ± standard deviation). LTS was significantly higher in the ACL-injured group (11.30° ± 3.52° versus 7.00° ± 2.63°, P = .0001), as were the absolute slope difference (7.10 ± 2.92° versus 3.14 ± 3.25°, P = .0002) and LTS:LMBA ratio (0.46 ± 0.17 versus 0.26 ± 0.12, P = .0001). No significant differences were observed for MTS or LMBA. Independent predictors were LTS (odds ratio [OR] 1.58, 95% confidence interval [CI] 1.18 to 2.13, P = .002), LTS:LMBA ratio (OR 3.13, 95% CI 1.48 to 6.62, P = .003), and absolute slope difference (OR 1.65, 95% CI 1.17 to 2.32, P = .005). LTS:LMBA ratio was the strongest predictor variable (area under the curve 0.86). CONCLUSION: This study suggests that LTS, absolute slope difference, and LTS:LMBA ratio are significant pediatric ACL-injury risk factors. All 3 demonstrate good predictive accuracy; however, the relationship between steep LTS and shallow LMBA was the strongest predictor. LEVEL OF EVIDENCE: III, case-control study.

Perioperative Systemic Dexamethasone Reduces Length of Stay in Total Joint Arthroplasty: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.

BACKGROUND: The objective of this review is to examine the effect of perioperative systemic corticosteroids at varying doses and timings on early postoperative recovery outcomes following unilateral total knee and total hip arthroplasty. The primary outcome was length of stay (LOS). METHODS: A systematic review and meta-analysis of randomized controlled trials was performed. MEDLINE, EMBASE, and Cochrane Library databases were searched from inception to June 1, 2020. Studies comparing the outcome of adult patients receiving a systemic steroid to patients who did not receive steroids were included. RESULTS: Seventeen studies were included, incorporating 1957 patients. Perioperative corticosteroids reduced hospital LOS (mean difference [MD] = -0.39 days, 95% confidence interval [CI] -0.61 to -0.18). A subsequent dose of corticosteroid at 24 hours further reduced LOS (MD = -0.33, 95% CI -0.55 to -0.11). Corticosteroids resulted in reduced levels of pain on postoperative day (POD) 0 (MD = -1.99, 95% CI -3.30 to -0.69), POD1 (MD = -1.47, 95% CI -2.15 to -0.79), and POD2. Higher doses were more effective in reducing pain with activity on POD0 (P = .006) and 1 (P = .023). Steroids reduced the incidence of PONV on POD1 (log odds ratio [OR] = -1.05, 95% CI -1.26 to -0.84) and POD2, with greater effect at higher doses (P = .046). Corticosteroids did not increase the incidence of infection (P = 1.000), venous thromboembolism (P = 1.000), or gastrointestinal hemorrhage (P = 1.000) but were associated with an increase in blood glucose (MD = 5.30 mg/dL, 95% CI 2.69-7.90). CONCLUSION: Perioperative corticosteroids are safe, facilitate earlier discharge, and improve patient recovery following unilateral total knee arthroplasty and total hip arthroplasty. Higher doses (15-20 mg of dexamethasone) are associated with further reductions in dynamic pain and PONV, and repeat dosing may further reduce LOS.

Immersive virtual reality enables technical skill acquisition for scrub nurses in complex revision total knee arthroplasty.

INTRODUCTION: Immersive Virtual Reality (iVR) is a novel technology which can enhance surgical training in a virtual environment without supervision. However, it is untested for the training to select, assemble and deliver instrumentation in orthopaedic surgery-typically performed by scrub nurses. This study investigates the impact of an iVR curriculum on this facet of the technically demanding revision total knee arthroplasty. MATERIALS AND METHODS: Ten scrub nurses completed training in four iVR sessions over a 4-week period. Initially, nurses completed a baseline real-world assessment, performing their role with real equipment in a simulated operation assessment. Each subsequent iVR session involved a guided mode, where the software taught participants the procedural choreography and assembly of instrumentation in a simulated operating room. In the latter three sessions, nurses also undertook an assessment in iVR. Outcome measures were related to procedural sequence, duration of surgery and efficiency of movement. Transfer of skills from iVR to the real world was assessed in a post-training simulated operation assessment. A pre- and post-training questionnaire assessed the participants knowledge, confidence and anxiety. RESULTS: Operative time reduced by an average of 47% across the 3 unguided sessions (mean 55.5 ± 17.6 min to 29.3 ± 12.1 min, p > 0.001). Assistive prompts reduced by 75% (34.1 ± 16.8 to 8.6 ± 8.8, p < 0.001), dominant hand motion by 28% (881.3 ± 178.5 m to 643.3 ± 119.8 m, p < 0.001) and head motion by 36% (459.9 ± 99.7 m to 292.6 ± 85.3 m, p < 0.001). Real-world skill improved from 11% prior to iVR training to 84% correct post-training. Participants reported increased confidence and reduced anxiety in scrubbing for rTKA procedures (p < 0.001). CONCLUSIONS: For scrub nurses, unfamiliarity with complex surgical procedures or equipment is common. Immersive VR training improved their understanding, technical skills and efficiency. These iVR-learnt skills transferred into the real world.

Climatically driven changes in primary production propagate through trophic levels.

Climate and land-use change are the major drivers of global biodiversity loss. Their effects are particularly acute for wide-ranging consumers, but little is known about how these factors interact to affect the abundance of large carnivores and their herbivore prey. We analyzed population densities of a primary and secondary consumer (mule deer, Odocoileus hemionus, and mountain lion, Puma concolor) across a climatic gradient in western North America by combining satellite-based maps of plant productivity with estimates of animal abundance and foraging area derived from Global Positioning Systems telemetry data (GPS). Mule deer density exhibited a positive, linear relationship with plant productivity (r2  = 0.58), varying by a factor of 18 across the climate-vegetation gradient (range: 38-697 individuals/100 km2 ). Mountain lion home range size decreased in response to increasing primary productivity and consequent changes in the abundance of their herbivore prey (range: 20-450 km2 ). This pattern resulted in a strong, positive association between plant productivity and mountain lion density (r2  = 0.67). Despite varying densities, the ratio of prey to predator remained constant across the climatic gradient (mean ± SE = 363 ± 29 mule deer/mountain lion), suggesting that the determinacy of the effect of primary productivity on consumer density was conserved across trophic levels. As droughts and longer term climate changes reduce the suitability of marginal habitats, consumer home ranges will expand in order for individuals to meet basic nutritional requirements. These changes portend decreases in the abundance of large-bodied, wide-ranging wildlife through climatically driven reductions in carrying capacity, as well as increased human-wildlife interactions stemming from anthropogenic land use and habitat fragmentation.

Does probability of occurrence relate to population dynamics?

Hutchinson defined species' realized niche as the set of environmental conditions in which populations can persist in the presence of competitors. In terms of demography, the realized niche corresponds to the environments where the intrinsic growth rate (r) of populations is positive. Observed species occurrences should reflect the realized niche when additional processes like dispersal and local extinction lags do not have overwhelming effects. Despite the foundational nature of these ideas, quantitative assessments of the relationship between range-wide demographic performance and occurrence probability have not been made. This assessment is needed both to improve our conceptual understanding of species' niches and ranges and to develop reliable mechanistic models of species geographic distributions that incorporate demography and species interactions. The objective of this study is to analyse how demographic parameters (intrinsic growth rate r and carrying capacity K) and population density (N) relate to occurrence probability (Pocc ). We hypothesized that these relationships vary with species' competitive ability. Demographic parameters, density, and occurrence probability were estimated for 108 tree species from four temperate forest inventory surveys (Québec, Western US, France and Switzerland). We used published information of shade tolerance as indicators of light competition strategy, assuming that high tolerance denotes high competitive capacity in stable forest environments. Interestingly, relationships between demographic parameters and occurrence probability did not vary substantially across degrees of shade tolerance and regions. Although they were influenced by the uncertainty in the estimation of the demographic parameters, we found that r was generally negatively correlated with Pocc , while N, and for most regions K, was generally positively correlated with Pocc . Thus, in temperate forest trees the regions of highest occurrence probability are those with high densities but slow intrinsic population growth rates. The uncertain relationships between demography and occurrence probability suggests caution when linking species distribution and demographic models.

The influence of interspecific interactions on species range expansion rates.

Ongoing and predicted global change makes understanding and predicting species' range shifts an urgent scientific priority. Here, we provide a synthetic perspective on the so far poorly understood effects of interspecific interactions on range expansion rates. We present theoretical foundations for how interspecific interactions may modulate range expansion rates, consider examples from empirical studies of biological invasions and natural range expansions as well as process-based simulations, and discuss how interspecific interactions can be more broadly represented in process-based, spatiotemporally explicit range forecasts. Theory tells us that interspecific interactions affect expansion rates via alteration of local population growth rates and spatial displacement rates, but also via effects on other demographic parameters. The best empirical evidence for interspecific effects on expansion rates comes from studies of biological invasions. Notably, invasion studies indicate that competitive dominance and release from specialized enemies can enhance expansion rates. Studies of natural range expansions especially point to the potential for competition from resident species to reduce expansion rates. Overall, it is clear that interspecific interactions may have important consequences for range dynamics, but also that their effects have received too little attention to robustly generalize on their importance. We then discuss how interspecific interactions effects can be more widely incorporated in dynamic modeling of range expansions. Importantly, models must describe spatiotemporal variation in both local population dynamics and dispersal. Finally, we derive the following guidelines for when it is particularly important to explicitly represent interspecific interactions in dynamic range expansion forecasts: if most interacting species show correlated spatial or temporal trends in their effects on the target species, if the number of interacting species is low, and if the abundance of one or more strongly interacting species is not closely linked to the abundance of the target species.

Survivorship and risk factors for revision of metal-on-metal hip resurfacing.

Aims: Metal-on-metal hip resurfacing (MoM-HR) has seen decreased usage due to safety and longevity concerns. Joint registries have highlighted the risks in females, smaller hips, and hip dysplasia. This study aimed to identify if reported risk factors are linked to revision in a long-term follow-up of MoM-HR performed by a non-designer surgeon. Methods: A retrospective review of consecutive MoM hip arthroplasties (MoM-HRAs) using Birmingham Hip Resurfacing was conducted. Data on procedure side, indication, implant sizes and orientation, highest blood cobalt and chromium ion concentrations, and all-cause revision were collected from local and UK National Joint Registry records. Results: A total of 243 hips (205 patients (163 male, 80 female; mean age at surgery 55.3 years (range 25.7 to 75.3)) with MoM-HRA performed between April 2003 and October 2020 were included. Mean follow-up was 11.2 years (range 0.3 to 17.8). Osteoarthritis was the most common indication (93.8%), and 13 hips (5.3%; 7M:6F) showed dysplasia (lateral centre-edge angle < 25°). Acetabular cups were implanted at a median of 45.4° abduction (interquartile range 41.9° - 48.3°) and stems neutral or valgus to the native neck-shaft angle. In all, 11 hips (4.5%; one male, ten females) in ten patients underwent revision surgery at a mean of 7.4 years (range 2.8 to 14.2), giving a cumulative survival rate of 94.8% (95% confidence interval (CI) 91.6% to 98.0%) at ten years, and 93.4% (95% CI 89.3% to 97.6%) at 17 years. For aseptic revision, male survivorship was 100% at 17 years, and 89.6% (95% CI 83.1% to 96.7%) at ten and 17 years for females. Increased metal ion levels were implicated in 50% of female revisions, with the remaining being revised for unexplained pain or avascular necrosis. Conclusion: The Birmingham MoM-HR showed 100% survivorship in males, exceeding the National Institute for Health and Care Excellence '5% at ten years' threshold. Female sex and small component sizes are independent risk factors. Dysplasia alone is not a contraindication to resurfacing.

5 year follow up of a hydroxyapatite coated short stem femoral component for hip arthroplasty: a prospective multicentre study.

Short stem, uncemented femoral implants for hip arthroplasty are bone conserving achieving stability through initial metaphyseal press-fit and biological fixation. This study aimed to evaluate the survivorship, mid-term function and health related quality of life outcomes in patients who have undergone total hip arthroplasty (THA) with a fully hydroxyapatite coated straight short stem femoral component with up to 5 years follow-up. 668 patients were recruited to a multicentre study investigating the performance of the cementless Furlong Evolution® stem for THA. 137 patients withdrew at various time points. The mean follow-up was 49 months. Clinical (Harris Hip Score (HHS), radiographic and patient-reported outcome measures-Oxford Hip Score (OHS) and EuroQol 5D (EQ-5D), were recorded pre-operatively and at 6 weeks, 6 months, 1 year, 3 year and 5 year follow ups. At 5-year follow-up, 12 patients underwent revision surgery, representing a cumulative revision rate of 1.8%. Median OHS, HHS and EQ5D scores improved significantly: OHS improved from a pre-operative median of 21 (IQR 14-26) to 47 (IQR 44-48) (p < 0.001). HHS improved from 52 (IQR 40-63) to 98 (IQR 92-100) (p < 0.001) and EQ5D improved from 70 (IQR 50-80) to 85 (IQR 75-95) (p < 0.001). This fully HA-coated straight short femoral stem implant demonstrated acceptable mid-term survivorship and delivered substantial improvements in function and quality of life after THA.

An automated, web-based triage tool may optimise referral pathways in elective orthopaedic surgery: A proof-of-concept study.

Introduction: Knee pain is caused by various pathologies, making evaluation in primary-care challenging. Subsequently, an over-reliance on imaging, such as radiographs and MRI exists. Electronic-triage tools represent an innovative solution to this problem. The aims of this study were to establish the magnitude of unnecessary knee imaging prior to orthopaedic surgeon referral, and ascertain whether an e-triage tool outperforms existing clinical pathways to recommend correct imaging. Methods: Patients ≥18 years presenting with knee pain treated with arthroscopy or arthroplasty at a single academic hospital between 2015 and 2020 were retrospectively identified. The timing and appropriateness of imaging were assessed according to national guidelines, and classified as 'necessary', 'unnecessary' or 'required MRI'. Based on an eDelphi consensus study, a symptom-based e-triage tool was developed and piloted to preliminarily diagnose five common knee pathologies and suggest appropriate imaging. Results: 1462 patients were identified. 17.2% (n = 132) of arthroplasty patients received an 'unnecessary MRI', 27.6% (n = 192) of arthroscopy patients did not have a 'necessary MRI', requiring follow-up. Forty-one patients trialled the e-triage pilot (mean age: 58.4 years, 58.5% female). Preliminary diagnoses were available for 33 patients. The e-triage tool correctly identified three of the four knee pathologies (one pathology did not present). 79.2% (n = 19) of participants would use the tool again. Conclusion: A substantial number of knee pain patients receive incorrect imaging, incurring delays and unnecessary costs. A symptom-based e-triage tool was developed, with promising performance and user feedback. With refinement using larger datasets, this tool has the potential to improve wait-times, referral quality and reduce cost.

A Simple Technique to Remove an Incarcerated Ceramic Liner in Revision Hip Arthroplasty.

Extraction of a well-fixed ceramic liner during revision total hip arthroplasty can be technically challenging, particularly when acetabular fixation screws prevent en bloc removal of the shell and insert without causing collateral damage to the adjacent pelvic bone. It is also important to remove the ceramic liner intact, as ceramic debris left in the joint may cause third body wear with premature articular wear of the revised implants. We describe a novel technique to extract an incarcerated ceramic liner when previously described strategies prove ineffective. Knowledge of this technique will help surgeons avoid unnecessary damage to the acetabular bone and optimize prospects for stable implantation of revision components.

Metabolic equivalent of task scores avoid the ceiling effect observed with conventional patient-reported outcome scores following knee arthroplasty.

The metabolic equivalent of task (MET) score examines patient performance in relation to energy expenditure before and after knee arthroplasty. This study assesses its use in a knee arthroplasty population in comparison with the widely used Oxford Knee Score (OKS) and EuroQol five-dimension index (EQ-5D), which are reported to be limited by ceiling effects. A total of 116 patients with OKS, EQ-5D, and MET scores before, and at least six months following, unilateral primary knee arthroplasty were identified from a database. Procedures were performed by a single surgeon between 2014 and 2019 consecutively. Scores were analyzed for normality, skewness, kurtosis, and the presence of ceiling/floor effects. Concurrent validity between the MET score, OKS, and EQ-5D was assessed using Spearman's rank. Postoperatively the OKS and EQ-5D demonstrated negative skews in distribution, with high kurtosis at six months and one year. The OKS demonstrated a ceiling effect at one year (15.7%) postoperatively. The EQ-5D demonstrated a ceiling effect at six months (30.2%) and one year (39.8%) postoperatively. The MET score did not demonstrate a skewed distribution or ceiling effect either at six months or one year postoperatively. Weak-moderate correlations were noted between the MET score and conventional scores at six months and one year postoperatively. In contrast to the OKS and EQ-5D, the MET score was normally distributed postoperatively with no ceiling effect. It is worth consideration as an arthroplasty outcome measure, particularly for patients with high expectations.

Deep brain stimulation in the treatment of chorea.

Deep brain stimulation has been used as a means of reducing dyskinesias in various conditions, including Parkinson's disease and dystonia for many years. Recently, owing to the clinical similarities between L-dopa induced dyskinesia and chorea, deep brain stimulation has now been implemented as a novel treatment method in both Huntington's disease and neuroacanthocytosis, and a paucity of case studies exist reporting its efficacy. This review will summarize the case studies of deep brain stimulation in both Huntington's disease and neuroacanthocytosis, and discuss the possible implications and limitations associated with these reports. As both these disorders are often refractory to medication and difficult to treat, deep brain stimulation may be a useful treatment option in the future.

Climatic extremes improve predictions of spatial patterns of tree species.

Understanding niche evolution, dynamics, and the response of species to climate change requires knowledge of the determinants of the environmental niche and species range limits. Mean values of climatic variables are often used in such analyses. In contrast, the increasing frequency of climate extremes suggests the importance of understanding their additional influence on range limits. Here, we assess how measures representing climate extremes (i.e., interannual variability in climate parameters) explain and predict spatial patterns of 11 tree species in Switzerland. We find clear, although comparably small, improvement (+20% in adjusted D(2), +8% and +3% in cross-validated True Skill Statistic and area under the receiver operating characteristics curve values) in models that use measures of extremes in addition to means. The primary effect of including information on climate extremes is a correction of local overprediction and underprediction. Our results demonstrate that measures of climate extremes are important for understanding the climatic limits of tree species and assessing species niche characteristics. The inclusion of climate variability likely will improve models of species range limits under future conditions, where changes in mean climate and increased variability are expected.

The metabolic equivalent of task score : a useful metric for comparing high-functioning hip arthroplasty patients.

AIMS: This study investigates the use of the metabolic equivalent of task (MET) score in a young hip arthroplasty population, and its ability to capture additional benefit beyond the ceiling effect of conventional patient-reported outcome measures. METHODS: From our electronic database of 751 hip arthroplasty procedures, 221 patients were included. Patients were excluded if they had revision surgery, an alternative hip procedure, or incomplete data either preoperatively or at one-year follow-up. Included patients had a mean age of 59.4 years (SD 11.3) and 54.3% were male, incorporating 117 primary total hip and 104 hip resurfacing arthroplasty operations. Oxford Hip Score (OHS), EuroQol five-dimension questionnaire (EQ-5D), and the MET were recorded preoperatively and at one-year follow-up. The distribution was examined reporting the presence of ceiling and floor effects. Validity was assessed correlating the MET with the other scores using Spearman's rank correlation coefficient and determining responsiveness. A subgroup of 93 patients scoring 48/48 on the OHS were analyzed by age, sex, BMI, and preoperative MET using the other metrics to determine if differences could be established despite scoring identically on the OHS. RESULTS: Postoperatively the OHS and EQ-5D demonstrate considerable negatively skewed distributions with ceiling effects of 41.6% and 53.8%, respectively. The MET was normally distributed postoperatively with no relevant ceiling effect. Weak-to-moderate significant correlations were found between the MET and the other two metrics. In the 48/48 subgroup, no differences were found comparing groups with the EQ-5D, however significantly higher mean MET scores were demonstrated for patients aged < 60 years (12.7 (SD 4.7) vs 10.6 (SD 2.4), p = 0.008), male patients (12.5 (SD 4.5) vs 10.8 (SD 2.8), p = 0.024), and those with preoperative MET scores > 6 (12.6 (SD 4.2) vs 11.0 (SD 3.3), p = 0.040). CONCLUSION: The MET is normally distributed in patients following hip arthroplasty, recording levels of activity which are undetectable using the OHS. Cite this article: Bone Joint Res 2022;11(5):317-326.

Balancing forest-regeneration probabilities and maintenance costs in dry grasslands of high conservation priority.

Abandonment of agricultural land has resulted in forest regeneration in species-rich dry grasslands across European mountain regions and threatens conservation efforts in this vegetation type. To support national conservation strategies, we used a site-selection algorithm (MARXAN) to find optimum sets of floristic regions (reporting units) that contain grasslands of high conservation priority. We sought optimum sets that would accommodate 136 important dry-grassland species and that would minimize forest regeneration and costs of management needed to forestall predicted forest regeneration. We did not consider other conservation elements of dry grasslands, such as animal species richness, cultural heritage, and changes due to climate change. Optimal sets that included 95-100% of the dry grassland species encompassed an average of 56-59 floristic regions (standard deviation, SD 5). This is about 15% of approximately 400 floristic regions that contain dry-grassland sites and translates to 4800-5300 ha of dry grassland out of a total of approximately 23,000 ha for the entire study area. Projected costs to manage the grasslands in these optimum sets ranged from CHF (Swiss francs) 5.2 to 6.0 million/year. This is only 15-20% of the current total estimated cost of approximately CHF30-45 million/year required if all dry grasslands were to be protected. The grasslands of the optimal sets may be viewed as core sites in a national conservation strategy.