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The aim of this paper is to report on fatal landslides resulting from two extraordinary storm events in January and February 2023, in Auckland, New Zealand, including the characteristics of the terrain, the site geology, and the storms. The January 27 Auckland Anniversary storm was from an “atmospheric river,” dumping Summer’s worth of rain (265 mm) in one day. This was the highest 24-h total on record, estimated a 1 in 200-year event, with a peak 2-min rainfall of 4.2 mm, coinciding with Friday’s evening “rush hour.” This led to widespread landsliding throughout Auckland, including a fatal landslide in Parnell, central Auckland. Notably, this occurred only meters from a similarly destructive landslide in 1997. With January 2023 Auckland’s wettest January on record, and with the region still in a state of emergency, Tropical Cyclone Gabrielle crossed the region on February 13–14. This also caused widespread landsliding, including a fatal landslide at Muriwai on the west Auckland coast. Fatal landslides from the same escarpment had occurred in 1965, close to the February 13, 2023, fatal landslide. Taken together, both storm events caused > 140,000 landslides across the North Island, and flooding, making hundreds of people homeless, with damage estimates of > US$8.6 billion (3.4% of NZ’s GDP). For future disaster risk reduction, attention should be paid to revising legislation and local planning, which currently allows people to legally build (and re-build) houses in landslide-prone areas of New Zealand.

The magnitude (Mw) 7.8 earthquake that struck North Canterbury on New Zealand’s South Island on the evening of 14 November 2016 caused widespread damage to infrastructure, in particular to road and rail within the South Kaikōura Transport Corridor (SKTC). This is the main transport corridor along the east coast of the South Island, and the coseismic landslides covered and destroyed parts of the State Highway 1 (SH1) road, as well as the railway lines. Post-earthquake aftershocks and significant rainfall events (e.g. Cyclones Debbie, Cook and Gita), further mobilised the de-stabilised greywacke rock mass and paleo-landslide debris that mantled the slopes. Indeed, the SKTC was affected by > 80 separate landslides that have impacted either the rail corridor, the road corridor, or both. A number of different landslide mechanisms occurred, including shallow translation slides of existing paleo-landslide debris and rotational slumping, as well as rock mass failure via wedge, planar or toppling. Here, we report on monitoring of three case study landslides, using multi-temporal analyses of digital elevation data (from LiDAR, TLS and UAV surveys), real-time extensometer and land deformation monitoring using GPS receivers, as well as survey prisms. These datasets provided important monitoring of near-surface movement, important for risk management along the transport corridor during the reinstatement works.

Landslides are widespread geomorphological features on the North Island of New Zealand, where they represent one of the primary landscape-forming processes. This study focuses on the steepland terrain surrounding Gisborne, a city located on the east coast of the North Island, at the Hikurangi subduction margin. This terrain consists of young, weak, sedimentary rocks and soils; the most common modes of slope failures are soil creep, slides and flows in shallow, clay-rich soil and regolith, triggered by heavy rainfall. Based on observational data from Sentinel-1 imagery, this study leverages results from interferometric synthetic aperture radar (InSAR) processing to reveal the distribution of deformation across Gisborne’s steepland periphery from January 2016 to December 2021. Velocities in the line of sight were obtained from the stack of interferograms and projected along the direction of maximum slope, to extract the true displacement on the slopes. The ascending and descending data sets were combined to reveal the vertical and horizontal components of the deformation. The results were combined with a regional LiDAR data set, aerial imagery and field observations to delineate areas of slope deformation. Finally, slope deformation time series data was compared with rainfall records to identify seasonal changes, due to shrinking and swelling of expansive soils. Although the InSAR displacement data contains some noise, results could be used to identify 132 unstable slopes within the study area, caused by soil creep and earthflows. Also, the shrink-swell of expansive soils causes a seasonal pattern of displacements, which varied by 10–20 mm/year between Austral winter and summer, strongly correlated to rainfall.

A brief investigation of an ongoing urban landslide complex in Auckland, New Zealand, is presented. After progressive deformation of a carpark surface in the centre of Birkenhead over several months, two landslides occurred, in October and November 2017. The landslides occurred adjacent to each other at the head of the Rawene Reserve area, with rotational slumping forming headscarps and each landslide developing an earthflow component with a runout over 100 m. The failures appear to be formed of fill and residual soil. While the residual soil is formed on Miocene East Coast Bays Formation sands and silts, historical aerial images reveal that the fill was emplaced on the slopes in the 1970s and 1980s within gullies, to allow the carpark to be built. The precise triggering mechanism of the landslide activity is unknown. Although rainfall-triggered landslides occurred over much of the Auckland region in early 2017 due to the passing of ex-tropical cyclone Debbie, total rainfall for 2017 in the area (1299 mm) closely mirrored the 1980–2010 ‘normal’ of 1231 mm. Anecdotal evidence from eyewitnesses in days leading up to the first landslide highlighted resident’s concerns about the effects of vibration from piling operations at a construction site adjacent to the carpark, where cracking and subsidence was evident. Thus, given the timeline of observations recorded at the site, and local geology, progressive failure along a weak surface, affected by dynamic loading from piling-induced vibrations, may have increased pore pressure and decreased the shear strength of the residual soil and fill.

Background Fixation choice (polymethyl-methacrylate bone cement or cementless implants) in total knee arthroplasty (TKA) varies widely across surgeons, reflecting differences in clinical judgment. While traditional statistical approaches are commonly used to study surgical decision-making, they may be limited in capturing complex and multifactorial relationships inherent in such data. This study evaluates how different supervised machine learning (SML) algorithms characterize fixation choice and prioritize predictors, rather than developing a clinical decision-support tool. Methods We analyzed data from the multicenter Patient-Centered Outcomes Research Institute (PCORI)-funded Comparative Effectiveness of Pulmonary Embolism Prevention after Hip and Knee Replacement (PEPPER) trial, linked with the American Hospital Association Annual Survey. Adult patients undergoing elective primary TKA for osteoarthritis between December 2016 and May 2024 were included. The primary outcome was the binary classification of cemented versus cementless fixation. Five models were evaluated (logistic regression, LASSO, support vector machine, XGBoost, and Random Forest). Model performance was assessed using discrimination, precision–recall performance, calibration, and F1 score within a nested cross-validation framework. All confidence intervals were estimated using surgeon-clustered bootstrap resampling. Permutation importance was used for cross-model feature comparison, and SHapley Additive exPlanations (SHAP) were applied to interpret the best-performing model. Results Among 7848 patients treated by 140 surgeons at 29 hospitals, 85.8% underwent cemented TKA. RF achieved the highest discriminatory performance (AUROC = 0.868; 95%CI:0.826–0.891, F1 = 0.944; 95%CI:0.927–0.951) and the lowest Brier score (0.080; 95%CI: 0.072–0.091). In the RF model, patient BMI and age emerged as the most influential predictors of fixation choice, with SHAP analyses indicating an inverse association between BMI and cemented fixation and a non-linear relationship between age and the likelihood of cemented TKA. In contrast, non-tree-based models more frequently prioritized hospital-level and geographic characteristics over patient factors. Conclusions Tree-based SML models, particularly RF, showed the highest performance in this cohort and prioritized patient-level predictors more consistently than non–tree-based models. Substantively, fixation choice within this study cohort was more strongly associated with patient-specific factors such as BMI and age. These findings may help inform understanding of how patient characteristics are associated with fixation choice in current clinical practice.

Background Existing studies of patient-reported outcomes (PRO) following total knee arthroplasty (TKA) based on fixation methods (cemented vs cementless) are limited to single centers with small sample sizes. Using multicentered data,, we compared baseline and early post-operative global and condition-specific PROs between patients undergoing cemented versus cementless TKA. Methods With PROs prospectively collected through Comparative Effectiveness Pulmonary Embolism Prevention After Hip and Knee Replacement (PEPPER) trial (ClinicalTrials.gov: NCT02810704), we examined pre- and post-operative (1, 3, and 6-months) outcomes in 5,961 patients undergoing primary TKA enrolled by 28 medical centers between December 2016 and August 2021. Outcomes included the short-form of the Knee Injury and Osteoarthritis Outcome Score (KOOS-Jr.), the Patient-Reported Outcomes Measurement Information System Physical Health (PROMIS-PH), and the Numeric Pain Rating Scale (NPRS). To minimize selection bias, we performed a 1-to-1 propensity score matched analysis to assess relative pre- to post-operative change in outcomes within and between cemented and cementless TKA groups. Results With greater than 90% follow-up, significant pre to- post-operative improvements were observed in both groups. At 6 months, the cemented TKA group achieved a 3.3 point (55% of the Minimum Clinically Important Difference) greater improvement in the mean KOOS-Jr. (95%CI: 0.36, 6.30; P  = 0.028) than did the cementless group with no significant between-group differences in PROMIS-PH and NPRS. Conclusions In a large cohort of primary TKAs, patients with cemented fixation reported early incremental benefit in KOOS-Jr. over those with cementless TKA. Future studies are warranted to capture longer follow-up of PROs.

The historically unstable Sunkist Bay cliff in Auckland, New Zealand, is formed of weak Pleistocene alluvial sediments, infilling a paleovalley eroded into Miocene sandstone. Weathered tephra layers dip at low angles out of the cliff, and part-control stability. The last major failure prior to 2017 occurred in 2011, immediately to the west of the 2017 failure. Despite the long-term history of instability, over the last two decades, residential property construction has continued to < 10 m of the cliff edge. On 5 April 2017, ex-tropical cyclone Debbie delivered 157 mm of rainfall in 24 h, the 3rd highest 24-h total in 40 years. This was preceded 1 month earlier by 210 mm of rainfall on 8 March (the ‘Tasman Tempest’ storm), locally a 1 in 100-year event. A seawall constructed at the base of the cliff may have acted to inhibit pore-water pressure reduction during March–April 2017, because horizontal drains were absent in the seawall directly in front of the 2017 slope failure. Irrespective of the exact process-mechanisms of the 2017 failure, this case study highlights the importance of careful land use planning and imposition of adequate setback distances in coastal zones in New Zealand, and globally.

Category: Ankle Arthritis; Other Introduction/Purpose: Ankle arthrodesis (AA) remains a reliable treatment option to address end-stage ankle pathology in appropriately selected patients. When successful, AA surgeries can yield high patient satisfaction and marked improvements in patient-reported outcomes. AA can be performed by orthopedic surgeons (MD or DO) and non-orthopedic surgeons (DPM). However, no prior study has compared surgical safety indicators of AA based on surgeon specialty. Methods: Utilizing Medicare claims from 2016 to 2019, we retrospectively identified patients ≥65 years of age who underwent AA based on CPT coding. Patients on Medicare Health Maintenance Organization (HMO), End-Stage Renal Disease (ESRD), age under 65, and dual-eligible patients were excluded. Within this dataset, provider specialty was identified from Part B (provider claim), allowing for comparisons between orthopedic and non-orthopedic surgeons. We compared groups based on readmission, all-complication, and infection rates within 1-year of AA using logistic regressions controlling for age, sex, race, and Charlson Comorbidity Index (CCI). To help mitigate bias, we also performed a propensity matched model with the same variables. Data were reported as percentage point (PPT) differences (95% CI) between groups, with a positive number indicating higher rate of complications among patients treated by non-orthopedic surgeons. Results: During our timeframe, 3,274 AA procedures were performed by orthopedic surgeons and 614 by non-orthopedic surgeons. Non-orthopedic surgeons performed AA on patients with greater comorbidities (CCI scores: 0, 1, 2+: 34.7%, 20.4%, 44.8%) compared to orthopedic surgeons (CCI scores: 28.2%, 16.4%, 55.4%) (p< 0.001). AA performed by non-orthopedic surgeons, compared to orthopedic surgeons, had higher all-cause readmission rates (46.1% vs. 39.4%, p=0.008), all-complication rates (72.3% vs. 63.7%, p< 0.001) as well as complications with readmission (49.9% vs. 43.9%, p=0.019) and without readmission (55.0% vs. 43.1%, p< 0.001). All-cause infection risk within 1-year was higher in non-orthopedic surgeons (16.2% vs. 9.3%, p< 0.001), and persisted in our propensity-matched analyses (6.9 ppt higher (CI: 2.2, 11.7), p=0.004). Differences in the other safety measures were largely attenuated in the propensity-matched analysis. Conclusion: AA performed by non-orthopedic surgeons had greater all-complication, readmission, and infection rates as compared to AA done by orthopedic surgeons. Infection risk most notably persisted in analyses controlling for comorbidities. Infection following AA can lead to devastating outcomes for patients. The implication of findings like these will require further study to better understand how foot and ankle care is administered to patients at a policy-level.

Landslide dams can be very dangerous, with inundation occurring via rising waters upstream, and flooding downstream via dam breaching. Here, we report on a landslide that dammed the Mangapoike River in eastern North Island, New Zealand. The landslide is a low-angle wedge failure in the Miocene weak rock sandstones and mudstones of the Tolaga Group, forming a landslide dam (volume c. 8 million m3) and a lake 50 m deep with a surface area of 0.35 km2, before explosives were used to form a dam spillway to decrease lake level. The landslide formed along an escarpment in northwest-dipping sandstones, and is characterised by a linear lateral scarp, a headscarp, and a bedding-plane rupture surface, which controlled the landslide block geometry. The headscarp and lateral scarp have developed along propagating vertical fractures. The slide surface is a smoothed, northwest-dipping bedding plane, and intersects the vertical fractures in the lateral scarp, forming a wedge. While the principal failure mechanism was sliding involving a single large wedge-shaped block, the rapid movement led to disintegration of most of the block. Part of the detached slide block remained intact, but most of the displaced mass forming the landslide dam is disaggregated blocks in a sandy-silty matrix. Rainfall and meteoric groundwater probably did not initiate failure. Instead, river incision of the dip slope toe, and overpressurisation of fluids that are known to accumulate in sandstones overlain by impermeable mudstones in the region, probably decreased the effective stress along the existing bedding plane, initiating failure.

Background: Medial ulnar collateral ligament (UCL) injuries of the elbow affect overhead athletes with an increasing incidence over the past few decades. Growing evidence supports UCL repair as a treatment option in patients with low-grade UCL injuries or complete avulsion tears without chronic degenerative changes of the ligament. With this evolution in treatment options, accurate epidemiological data are needed to better understand and treat these injuries. Purpose: To investigate the trends of elbow UCL repair and reconstruction as it relates to the incidence of surgically managed UCL injury diagnoses from 2016 to 2022. Study Design: Descriptive epidemiology study; Level of evidence, 3. Methods: The Agency for Healthcare Research and Quality's Nationwide Ambulatory Surgical Sample database was examined from the period of 2016 to 2022. Patient demographics, diagnosis codes from the International Classification of Diseases, 10th Revision, Clinical Modification, and Current Procedural Terminology codes were collected, and descriptive statistics reported for those who underwent elbow UCL reconstruction versus repair. Survey-weighted Poisson regression, including covariates for age and sex, was used to report trends in UCL procedures from 2016 through 2022. A subgroup of patients 10 to 39 years old was analyzed to approximate the population of overhead athletes. Results: From 2016 to 2022, there was a relatively greater increase in volume of UCL repairs compared with reconstructions performed (129% vs 0%). Among the 10- to 39-year-old population, there was an increased incidence of outpatient visits coded with UCL injury diagnoses by 59% (age-adjusted incidence rate ratio [IRR], 1.60; 95% CI, 1.25-2.06; P < .001). There was an increased incidence of repair by 150% (age-adjusted IRR, 2.53; 95% CI, 2.11-3.03; P < .001) and a stable incidence of reconstruction (age-adjusted IRR, 0.97; 95% CI, 0.88-1.08; P = .63). Conclusion: Outpatient encounters for UCL injury and incidence of UCL repairs increased with a stable incidence of UCL reconstructions from 2016 to 2022. This may suggest UCL repair is becoming a more favorable treatment option for certain UCL injuries; however, further studies evaluating indications and outcomes of UCL repair versus reconstruction are warranted to guide management.