Prevalence of Physical Frailty: Results from the DO-HEALTH Study.

BACKGROUND: Frailty is a geriatric syndrome associated with multiple negative health outcomes. However, its prevalence varies by population and instrument used. We investigated frailty and pre-frailty prevalence by 5 instruments in community-dwelling older adults enrolled to a randomized-controlled trial in 5 European countries. METHODS: Cross-sectional baseline analysis in 2,144 DO-HEALTH participants recruited from Switzerland, Austria, France, Germany, and Portugal with complete data for frailty. Frailty status was assessed by the Physical Frailty Phenotype [PFP], SOF-Frailty Index [SOF-FI], FRAIL-Scale, SHARE-Frailty Instrument [SHARE-FI], and a modified SHARE-FI, and compared by country, age, and gender. Logistic regression was used to determine relevant factors associated with frailty and pre-frailty. RESULTS: Mean age was 74.9 (±4.4) years, 61.6% were women. Based on the PFP, overall frailty and pre-frailty prevalence was 3.0% and 43.0%. By country, frailty prevalence was highest in Portugal (13.7%) and lowest in Austria (0%), and pre-frailty prevalence was highest in Portugal (57.3%) and lowest in Germany (37.1%). By instrument and overall, frailty and pre-frailty prevalence was highest based on SHARE-FI (7.0% / 43.7%) and lowest based on SOF-FI (1.0% / 25.9%). Frailty associated factors were residing in Coimbra (Portugal) [OR 12.0, CI 5.30-27.21], age above 75 years [OR 2.0, CI 1.17-3.45], and female gender [OR 2.8, CI 1.48-5.44]. The same three factors predicted pre-frailty. CONCLUSIONS: Among relatively healthy adults age 70 and older enroled to DO-HEALTH, prevalence of frailty and pre-frailty differed significantly by instrument, country, gender, and age. Among instruments, the highest prevalence of frailty and pre-frailty was documented by the SHARE-FI and the lowest by the SOF-FI.

Coupling Single Photons from Discrete Quantum Emitters in WSe2 to Lithographically Defined Plasmonic Slot Waveguides.

We report the observation of the generation and routing of single plasmons generated by localized excitons in a WSe2 monolayer flake exfoliated onto lithographically defined Au-plasmonic waveguides. Statistical analysis of the position of different quantum emitters shows that they are (3.3 ± 0.7) times more likely to form close to the edges of the plasmonic waveguides. By characterizing individual emitters, we confirm their single-photon character via the observation of antibunching in the signal ( g(2)(0) = 0.42) and demonstrate that specific emitters couple to modes of the proximal plasmonic waveguide. Time-resolved measurements performed on emitters close to and far away from the plasmonic nanostructures indicate that Purcell factors up to 15 ± 3 occur, depending on the precise location of the quantum emitter relative to the tightly confined plasmonic mode. Measurement of the point spread function of five quantum emitters relative to the waveguide with <50 nm precision is compared with numerical simulations to demonstrate the potential for greater increases in the coupling efficiency for ideally positioned emitters. The integration of such strain-induced quantum emitters with deterministic plasmonic routing is a step toward deep-subwavelength on-chip single quantum light sources.

A few-emitter solid-state multi-exciton laser.

We report on non-conventional lasing in a photonic-crystal nanocavity that operates with only four solid-state quantum-dot emitters. In a comparison between microscopic theory and experiment, we demonstrate that irrespective of emitter detuning, lasing with [Formula: see text] is facilitated by means of emission from dense-lying multi-exciton states. In the spontaneous-emission regime we find signatures for radiative coupling between the quantum dots. The realization of different multi-exciton states at different excitation powers and the presence of electronic inter-emitter correlations are reflected in a pump-rate dependence of the ß-factor.

Extracellular matrix mimicking scaffold promotes osteogenic stem cell differentiation: A new approach in osteoporosis research.

BACKGROUND: Osteoporosis is a common metabolic disease, with mesenchymal stem cells discussed to play an important role in its pathomechanism. For in vitro osteoporosis studies, selection of adequate culture conditions is mandatory so as to preserve cell properties as far as possible. A suitable cell culture surface would ideally provide reproducible experimental conditions by resembling those in-vivo. OBJECTIVE: Generating an improved growth surface for osteogenic differentiation of human bone marrow derived mesenchymal stem cells (hBMSCs). METHODS: We modified electrospun gelatine meshes with hydroxyapatite nanopowder. The potential beneficial impact of the ensuing culture conditions were evaluated by cultivating and comparing the growth of cells from osteoporotic and non-osteoporotic donors on either hydroxyapatite-gelatine (HA) meshes, pure gelatine meshes, or 2D standard tissue culture surfaces. RESULTS: After 21 days of differentiation, cells grown on pure or HA-gelatine meshes showed significantly higher mineralization levels compared to cells cultured in standard conditions. The amount of mineralization varied considerably in hBMSC cultures of individual patients but showed no significant difference between stem cells obtained from osteoporotic or non-osteoporotic donors. CONCLUSIONS: Overall, these results indicate that the use of HA-gelatine meshes as growth surfaces may serve as a valuable tool for cultivation and differentiation of mesenchymal stem cells along the osteogenic lineage, facilitating future research on osteoporosis and related issues.

Treatment of acetabular fractures in older patients-introduction of a new implant for primary total hip arthroplasty.

BACKGROUND: Fractures of the acetabulum in younger patients are commonly treated by open reduction and internal fixation. For elderly patients, stable primary total hip arthroplasty with the advantage of immediate postoperative mobilization might be the adequate treatment. For this purpose, a sufficiently stable fixation of the acetabular component is required. MATERIALS AND METHODS: Between August 2009 and 2014, 30 cases were reported in which all patients underwent total hip arthroplasty additionally to a customized implant designed as an antiprotrusion cage. Inclusion criteria were an acetabular fracture with or without a previous hemiarthroplasty, age above 65 years, and pre-injury mobility dependent on a walking frame at the most. The median age was 79.9 years (65-92), and of 30 fractures, 25 were primary acetabular fractures (83%), four periprosthetic acetabular fractures (14%), and one non-union after a failed ORIF (3%). RESULTS: The average time from injury to surgery was 9.4 days (3-23) and 295 days for the non-union case. Mean time of surgery was 154.4 min (range 100 to 303). In 21 cases (70%), mobilization with full weight bearing was possible within the first 10 days. Six patients died before the follow-up examination 3 and 6 months after surgery, while 24 patients underwent radiologic examination showing consolidated fractures in bi-plane radiographs. In 9 patients, additional CT scan was performed which confirmed the radiographical results. 13 had regained their pre-injury level of mobility including the non-union case. Only one patient did not regain independent mobility. Four complications were recognized with necessary surgical revision (one prosthetic head dislocation, one pelvic cement leakage, one femoral shaft fracture, and one infected hematoma). CONCLUSION: The presented cage provides the possibility of early mobilization with full weight bearing which represents a valuable addition to the treatment spectrum in this challenging patient group.

EULAR/EFORT recommendations for management of patients older than 50†years with a fragility fracture and prevention of subsequent fractures.

The European League Against Rheumatism (EULAR) and the European Federation of National Associations of Orthopaedics and Traumatology (EFORT) have recognised the importance of optimal acute care for the patients aged 50 years and over with a recent fragility fracture and the prevention of subsequent fractures in high-risk patients, which can be facilitated by close collaboration between orthopaedic surgeons and rheumatologists or other metabolic bone experts. Therefore, the aim was to establish for the first time collaborative recommendations for these patients. According to the EULAR standard operating procedures for the elaboration and implementation of evidence-based recommendations, 7 rheumatologists, a geriatrician and 10 orthopaedic surgeons met twice under the leadership of 2 convenors, a senior advisor, a clinical epidemiologist and 3 research fellows. After defining the content and procedures of the task force, 10 research questions were formulated, a comprehensive and systematic literature search was performed and the results were presented to the entire committee. 10 recommendations were formulated based on evidence from the literature and after discussion and consensus building in the group. The recommendations included appropriate medical and surgical perioperative care, which requires, especially in the elderly, a multidisciplinary approach including orthogeriatric care. A coordinator should setup a process for the systematic investigations for future fracture risk in all elderly patients with a recent fracture. High-risk patients should have appropriate non-pharmacological and pharmacological treatment to decrease the risk of subsequent fracture.

Do we still need autopsy in times of modern multislice computed tomography?-Missed diagnoses in the emergency room.

INTRODUCTION: In spite of increasing quality of emergency room (ER) assessment in trauma patients and improved accuracy of modern multislice computed tomography (MSCT), the number of potentially missed diagnoses is still controversial. The aim of this study was to compare the initial findings of ER assessment and MSCT to the findings during autopsy in trauma patients not surviving the first 48 h after admission. We hypothesized that autopsy was more accurate than MSCT in diagnosing potentially fatal diagnoses. PATIENTS AND METHODS: Between January 2004 and September 2007, all trauma patients undergoing ER treatment in our institution who deceased within 48 h after admission were analyzed regarding diagnoses from initial ER assessment, including MSCT, and diagnoses from autopsy. Data were prospectively collected and retrospectively analyzed. Autopsy reports were compared to diagnoses of ER assessment and MSCT. Missed diagnoses (MD) and missed potentially fatal diagnoses (MPFD) were analyzed. RESULTS: Seventy-three patients with a mean age of 53.2 years were included into the study. Sixty-three percent were male. Autopsy revealed at least one missed diagnosis in 25% of the patients, with the thoracic area accounting for 67% of these. At least one MPFD was found in 4.1% of the patients, all of them being located in the thorax. Total numbers of MD and MPFD were significantly lower for the newer CT generation (64 MSCT, N = 11), compared to older one (4 MSCT, N = 26). CONCLUSIONS: As determined by autopsy, modern multislice computed tomography is an accurate method to diagnose injuries. However, 25% of all diagnoses, and 4.1% of potentially fatal diagnoses are still missed in trauma patients, who deceased within the first 48 h after admission. Therefore, autopsy seems to be necessary to determine potentially missed diagnoses for both academic and medicolegal reasons as well as for quality control.

Orthogeriatric co-management improves the outcome of long-term care residents with fragility fractures.

BACKGROUND: Fragility fractures are a major health care problem worldwide. Both hip and non-hip fractures are associated with excess mortality in the years following the fracture. Residents of long-term nursing homes represent a special high-risk group for poor outcomes. Orthogeriatric co-management models of care have shown in multiple studies to have medical as well as economic advantages, but their impact on this high-risk group has not been well studied. OBJECTIVE: We studied the outcome of long-term care residents with hip and non-hip fractures admitted to a geriatric fracture center. METHODS: The study design is a single center, prospective cohort study at a level-I trauma center in Austria running a geriatric fracture center. The cohort included all fragility fracture patients aged over 70 admitted from a long-term care residence from May 2009 to November 2011. The data set consisted of 265 patients; the mean age was 86.8 ± 6.7 years, and 80 % were female. The mean follow-up after the index fracture was 789 days, with a range from 1 to 1842 days. Basic clinical and demographic data were collected at hospital admission. Functional status and mobility were assessed during follow-up at 3, 6, and 12 months. Additional outcome data regarding readmissions for new fractures were obtained from the hospital information database; mortality was crosschecked with the death registry from the governmental institute of epidemiology. RESULTS: 187 (70.6 %) patients died during the follow-up period, with 78 patients (29.4 %) dying in the first year. The mean life expectancy after the index fracture was 527 (±431) days. Differences in mortality rates between hip and non-hip fracture patients were not statistically significant. Compared to reported mortality rates in the literature, hip fracture patients in this orthogeriatric-comanaged cohort had a significantly reduced one-year mortality [OR of 0.57 (95 % CI 0.31-0.85)]. After adjustment for confounders, only older age (OR 1.091; p = 0.013; CI 1.019-1.169) and a lower Parker Mobility Scale (PMS) (OR 0.737; p = 0.022; CI 0.568-0.957) remained as independent predictors. During follow-up, 62 patients (23.4 %) sustained at least one subsequent fracture, and 10 patients (3.4 %) experienced multiple fractures; 29 patients (10.9 %) experienced an additional fracture within the first year. Nearly, half (47.1 %) regained their pre-fracture mobility based on the PMS. CONCLUSION: Despite the generally poor outcomes for fragility fracture patients residing in long-term care facilities, orthogeriatric co-management appears to improve the outcome of high-risk fragility fracture patients. One-year mortality was 29.4 % in this cohort, significantly lower than in comparable trials. Orthogeriatric co-management may also have positive impacts on both functional outcome and the risk of subsequent fractures.

Trochanteric fragility fractures : Treatment using the cement-augmented proximal femoral nail antirotation.

OBJECTIVE: Use of standardized cement augmentation of the proximal femur nail antirotation (PFNA) for the treatment of trochanteric fragility fractures, which are associated with high morbidity and mortality, to achieve safer conditions for immediate full weight-bearing and mobilization, thus, improving preservation of function and independency of orthogeriatric patients. INDICATIONS: Trochanteric fragility fractures (type 31-A1-3). CONTRAINDICATIONS: Ipsilateral arthritis of the hip, leakage of contrast agent into the hip joint, femoral neck fractures. SURGICAL TECHNIQUE: Reduction of the fracture on a fracture table if possible, or minimally invasive open reduction of the proximal femur, i. e., using collinear forceps if necessary. Positioning of guidewires for adjustment of the PFNA and the spiral blade, respectively. Exclusion of leakage of contrast agent and subsequent injection of TRAUMACEM™ V(+) into the femoral head-neck fragment via a trauma needle kit introduced into the spiral blade. Dynamic or static locking of the PFNA at the diaphyseal level. POSTOPERATIVE MANAGEMENT: Immediate mobilization of the patients with full weight-bearing and secondary prevention, such as osteoporosis management is necessary to avoid further fractures in the treatment of these patients. RESULTS: A total of 110 patients older than 65 years underwent the procedure. Of the 72 patients available for follow-up (average age 85.3 years), all fractures healed after an average of 15.3 months. No complications related with cement augmentation were observed. Approximately 60 % of patients achieved the mobility level prior to trauma.

Allograft augmentation in proximal humerus fractures.

OBJECTIVE: Achieve stable fixation to initially start full range of motion (ROM) and to prevent secondary displacement in unstable fracture patterns and/or weak and osteoporotic bone. INDICATIONS: (Secondarily) displaced proximal humerus fractures (PHF) with an unstable medial hinge and substantial bony deficiency, weak/osteoporotic bone, pre-existing psychiatric illnesses or patient incompliance to obey instructions. CONTRAINDICATIONS: Open/contaminated fractures, systemic immunodeficiency, prior graft-versus-host reaction. SURGICAL TECHNIQUE: Deltopectoral approach. Identification of the rotator cuff. Disimpaction and reduction of the fracture, preparation of the situs. Graft preparation. Allografting. Fracture closure. Plate attachment. Definitive plate fixation. Radiological documentation. Postoperative shoulder fixation (sling). POSTOPERATIVE MANAGEMENT: Cryotherapy, anti-inflammatory medication on demand. Shoulder sling for comfort. Full active physical therapy as tolerated without pain. Postoperative radiographs (anteroposterior, outlet, and axial [as tolerated] views) and clinical follow-up after 6 weeks and 3, 6, and 12 months. RESULTS: Bony union and allograft incorporation in 9 of 10 noncompliant, high-risk patients (median age 63 years) after a mean follow-up of 28.5 months. The median Constant-Murley Score was 72.0 (range 45-86). Compared to the uninjured contralateral side, flexion was impaired by 13 %, abduction by 14 %, and external rotation by 15 %. Mean correction of the initial varus displacement was 38° (51° preoperatively to 13° postoperatively).

Treatment of periprosthetic acetabular fractures after previous hemi- or total hip arthroplasty: Introduction of a new implant.

OBJECTIVE: Treatment of displaced periprosthetic acetabular fractures in elderly patients. The goal is to stabilize an acetabular fracture independent of the fracture pattern, by inserting the custom-made roof-reinforcement plate and starting early postoperative full weight-bearing mobilization. INDICATIONS: Acetabular fracture with or without previous hemi- or total hip arthroplasty. CONTRAINDICATIONS: Non-displaced acetabular fractures. SURGICAL TECHNIQUE: Watson-Jones approach to provide accessibility to the anterior and supraacetabular part of the iliac bone. Angle-stable positioning of the roof-reinforcement plate without any fracture reduction. Cementing a polyethylene cup into the metal plate and restoring prosthetic femoral components. POSTOPERATIVE MANAGEMENT: Full weight-bearing mobilization within the first 10 days after surgery. In cases of two column fractures, partial weight-bearing is recommended. RESULTS: Of 7 patients with periprosthetic acetabular fracture, 5 were available for follow-up at 3, 6, 6, 15, and 24 months postoperatively. No complications were recognized and all fractures showed bony consolidation. Early postoperative mobilization was started within the first 10 days. All patients except one reached their preinjury mobility level. This individual and novel implant is custom made for displaced acetabular and periprosthetic fractures in patients with osteopenic bone. It provides a hopeful benefit due to early full weight-bearing mobilization within the first 10 days after surgery. LIMITATIONS: In case of largely destroyed supraacetabular bone or two-column fractures according to Letournel additional synthesis via an anterior approach might be necessary. In these cases partial weight bearing is recommended.

Does MIPO of fractures of the distal femur result in more rotational malalignment than ORIF? A retrospective study.

PURPOSE: Intraoperative control of rotational malalignment poses a big challenge for surgeons when using modern MIPO (minimally invasive plate osteosynthesis) techniques. We hypothesized that distal femoral fractures treated with MIPO technique are more often fixed in malrotation than those treated with open reduction internal fixation (ORIF). METHODS: In this retrospective study, we identified 20 patients who met the inclusion criteria and agreed to take part in the study. In ten patients MIPO was applied, in the other ten ORIF was used. Mean age was 44.8 (19-71 years). Functional status was assessed using clinical scores (Harris Hip Score, WOMAC Hip, KS Score, WOMAC Knee, Kujala Score). Rotational alignment was assessed with magnetic resonance imaging and compared to the opposite leg. RESULTS: We discovered a significant difference in the mean rotational difference between the MIPO group (14.3°) and the ORIF group (5.2°). Functionally, patients in the ORIF group outperformed patients in the MIPO group in all clinical scoring systems although no one proved to be statistically significant. MIPO technique was associated with significantly more rotational malalignment compared to ORIF in distal femur fracture fixation. However, implant failure and nonunion was more common in the ORIF group, with a revision rate of 3 versus 1 in the ORIF group. Clinical scoring did not significantly different between both groups. CONCLUSION: Taking into account the undisputable advantages of minimally invasive surgery, improved teaching of methods to avoid malrotation as well as regular postoperative investigations to detect any malrotation should be advocated.

[Treatment concept for a traumatic lesion of the prepatellar bursa]. / Behandlung der traumatisch eröffneten Bursa praepatellaris.

OBJECTIVE: Rapid recovery of the skin and soft tissue of the affected knee joint with surgical debridement of the wound and gentle, as well as risk-balanced partial resection of the traumatic lacerated prepatellar bursa. Functional aftercare with directed administration of antibiotics only. INDICATIONS: Acute, traumatic laceration of the prepatellar bursa. CONTRAINDICATIONS: Heavy contamination of the wound. Large, not closable skin defect or deep abrasion. Preexisting local infection. Additional fracture of the patella. Limited patient's cooperation, e. g., alcohol addiction or dementia. SURGICAL TECHNIQUE: Subdermal application of local anesthesia through the exposed wound margins. Exploration of the wound and excision of the wound margins. Dissection of the boundary layer between the bursa and the subcutaneous fat. Debridement of the wound and excision of the bruised and contaminated bursa tissue. Repetitive rinsing. Insertion of loop drainage. Single-layer wound closure. Crepe bandage. POSTOPERATIVE MANAGEMENT: Crepe bandage until the first wound inspection. Wound inspection on postoperative day 2 with removal of the loop. Pain-adapted functional treatment. Antithrombotic therapy until full weight-bearing. Removal of the stitches on postoperative day 14. Antibiotic prophylaxis (1st generation cephalosporin) for immunocompromised or polymorbid patients or heavily contaminated wounds. RESULTS: In 2013, we treated 50 traumatic lacerations of the prepatellar bursa. Four had to undergo further surgical treatment after primary care. In two other patients, one infected and one non-infected wound healing complication developed, which could be treated conservatively.

[Augmentation techniques on the proximal femur]. / Augmentationstechnik am proximalen Femur.

BACKGROUND: Due to the demographic change fractures of the proximal femur are an increasing major healthcare problem and are associated with the highest mortality among frailty fractures. OBJECTIVES: These mainly osteoporosis-associated fractures of the hip often represent a surgical challenge and the outcome has a decisive influence on the preservation of function and independency of orthogeriatric patients. Augmentation techniques could improve the stability of osteosynthesis in proximal femoral fractures. METHODS: Cement augmentation of proximal femoral nailing (PFNA) for the treatment of pertrochanteric femoral fractures is the most commonly used and standardized method of augmentation for these fractures by which a safer condition for immediate full weight bearing and mobilization can be achieved. RESULTS: In biomechanical and clinical studies good fracture healing was shown and there was no evidence of cement-associated complications in augmented PFNA nailing. In the majority of patients the mobility level prior to trauma could be achieved. CONCLUSION: In addition to the optimal surgical treatment, secondary prevention such as osteoporosis management to avoid further fractures is crucial in the treatment of these patients. This article is based on the current literature and provides an overview of the possible applications of cement augmentation for the treatment of proximal femoral fractures. In addition the surgical approach as well as previous scientific data on an established osteosynthesis using cement-augmented PFNA for the treatment of pertrochanteric frailty fractures are presented.

[Proximal femoral fractures in the elderly]. / Hüftgelenknahe Femurfrakturen des älteren Menschen.

Proximal femoral fractures represent an increasing major healthcare problem due to the demographic changes in this aging population and are associated with the highest mortality among fractures in elderly patients after suffering insufficiency injuries (so-called fragility fractures). The main aim in the treatment of orthogeriatric patients who suffered from a proximal femoral fracture is the preservation of function and independency. Given the high prevalence of comorbidities in these patients, interdisciplinary and interprofessional approaches are required. The use of modern osteosynthesis procedures can provide an improved, individualized surgical treatment with early full weight bearing of the affected extremity. Another aspect is the accompanying geriatric treatment which is associated with a significant reduction of perioperative and postoperative complications. In addition to acute treatment, the organization of secondary fracture prevention is a crucial pillar of treatment. This article provides an overview of the essential elements of orthogeriatric trauma surgery in elderly patients following proximal femoral fractures.

[Co-management in geriatric traumatology]. / Komanagement in der Alterstraumatologie.

BACKGROUND: Fragility fractures are becoming more common and are leading to significantly increased morbidity and mortality rates. METHOD: In order to improve the outcome of these patients, they are increasingly being treated from the beginning interdisciplinarily and interprofessionally as part of co-management models. The main contents of these systems are rapid surgical stabilization for rapid remobilization, treatment with standardized paths and regular communication within the team and a well-functioning discharge management. Furthermore, the organization is a key ingredient in secondary prevention of geriatric traumatology. CONCLUSION: If this system can be implemented as a whole, this will lead to an improvement of the functional outcomes for the patient as well as to cost savings.

[Factors Associated with the Use of Protective Gear among Adults during Recreational Sledging]. / Einflussfaktoren auf das Tragen von Schutzausrüstung bei erwachsenen Rodlern.

BACKGROUND: Recreational sledging (tobogganing) is a very popular winter sport in the Alps. Therefore, injury prevention through the usage of protective gear seems important. Therefore, the aim of this study was to evaluate factors associated with the use of protective gear among adults during recreational sledging. METHODS: Adult recreational sledgers were interviewed during the winter seasons 2012/13 and 2013/14 at six sledging tracks in Austria on demographics, skill level, sledging frequency, risk taking behaviour, sitting alone or with another person on the sledge, previous sledging-related injuries, and use of protective gear, respectively. Interviews were conducted on all days of the week. RESULTS: A total of 1968 adult sledgers (49.4 % females) with a mean age of 37.1 ±â€Š14.4 years participated in this study. A (ski) helmet, sun or snow goggles, a back protector, and wrist guards were used by 42.3 %, 71.0 %, 5.9 %, 2.6 % of sledgers, respectively. Helmet use was significantly higher with increasing age and increasing skill level as well as when sitting alone compared to sitting together with another person. Females, Austrians, persons sitting alone on the sledge, a higher frequency of sledging and a higher skill level were significantly associated with an increasing use of goggles. A back protector was significantly more often worn by younger people, more risky sledgers, and persons with a previous sledging-related injury. Wrist guards were significantly more often used by persons with a previous sledging-related injury. CONCLUSION: During recreational sledging, the factors age, sex, nationality, skill level, sitting alone compared to sitting together with another person on the sledge, sledging frequency, and injury experience were associated with the frequencies of usage of different types of protective gear. These factors should be considered when implementing preventive measures for recreational sledging.