Movement profiles of elite women soccer players during international matches and the effect of opposition's team ranking.

Abstract Movement patterns in elite men's soccer have been reported in depth, but less research exists for women's soccer. Aims of the study were to identify the movement profiles of elite women soccer players in international competition and examine the effect the level of opposition, based on Federation Internationale de Football Association (FIFA) rankings, had on the physical demands of the game. MinimaxX athlete tracking devices were used by 15 players during 13 international matches against opponent teams of varying ability. Total distance covered averaged 9292 ± 175 m. There was a decrease in high-intensity running (HIR) in the 60- to 75-min and 75- to 90-min periods compared to the 0- to 15-min period of 22.4% and 26.1%, respectively (P = 0.022, P = 0.004) although sprint distances remained unchanged across game periods. HIR distances covered were significantly greater for midfielders versus defenders, while defenders had lower sprinting compared to both midfielders and attackers. Stronger opponents elicited less HIR and greater low-speed activity (LSA) compared to playing teams of similar or lower ranking. These results are important to coaches to prepare players for international competition and show the differing demands required depending on the ability of the opponents.

Venom extraction method influences venom composition and potency in the giant house spider Eratigena atrica (C. L. Koch, 1843).

Extraction is the first step when investigating venom composition and function. In small invertebrates, widely used extraction methods include electrostimulation and venom gland extraction, however, the influence of these methods on composition and toxicology is poorly understood. Using the Giant House Spider Eratigena atrica as a model, we show that electrostimulation and venom gland removal extraction methods produce different protein profiles as assessed by Coomassie-stained SDS-PAGE and significantly different potencies in the cricket Acheta domesticus.

MRI-Based Score for Assessment of Bone Mineral Density in Operative Spine Patients.

STUDY DESIGN: Retrospective comparison. OBJECTIVE: The aim was to determine whether a previously developed magnetic resonance imaging (MRI)-derived bone mineral density (BMD) scoring system can differentiate between healthy and osteoporotic vertebrae and to validate this scoring system against quantitative computed tomography measurements. SUMMARY OF BACKGROUND DATA: BMD is an important preoperative consideration in spine surgery. Techniques to measure BMD are subject to falsely elevated values in the setting of spondylosis (dual-energy X-ray absorptiometry) or require significant exposure to radiation [quantitative computed tomography (QCT)]. Previous studies have shown that MRI may be utilized to measure bone quality using changes in the bone marrow signal observed on T1-weighted MRIs. MATERIALS AND METHODS: Retrospective study of patients who underwent operative lumbar procedures at a single tertiary institution between 2016 and 2021 (n=61). Vertebral bone quality (VBQ) scores were measured by dividing the median signal intensities of L1-L4 by the signal intensity of cerebrospinal fluid on noncontrast T1W MRI. Demographic data, comorbidities, VBQ scores, and QCT-derived T scores and BMD of the lumbar spine were compared between healthy ( T score ≥-1; n=21), osteopenic (-2.5 < T score < -1; n=21), and osteoporotic ( T score ≤-2.5; n=19) cohorts using analysis of variance with post hoc Tukey test. Linear regression and receiver operating characteristic curve analyses were performed to assess the predictive value of VBQ scores. Pearson correlation test was used to evaluate the association between VBQ scores and QCT-derived measurements. RESULTS: VBQ differentiated between healthy and osteoporotic groups ( P =0.009). Receiver operating characteristic curve analysis revealed that a greater VBQ score was associated with presence of osteoporosis (area under the curve=0.754, P =0.006). Cutoff VBQ for osteoporosis was 2.6 (Youden index 0.484; sensitivity: 58%; specificity: 90%). VBQ scores weakly correlated with QCT-derived BMD ( P =0.03, r =-0.27) and T scores ( P =0.04, r =-0.26). CONCLUSION: This study attempted to further validate a previously developed MRI-based BMD scoring system against QCT-derived measurements. VBQ score was found to be a significant predictor of osteoporosis and could differentiate between healthy and osteoporotic vertebrae.

Is High-Dose Tranexamic Safe in Spine Surgery? A Systematic Review and Meta-Analysis.

STUDY DESIGN: Literature review and meta-analysis. OBJECTIVES: Single-center series may be underpowered to detect whether high-dose (HD) tranexamic acid (TXA) confers a higher risk of complications. We sought to determine the safety and efficacy of HD TXA as compared to low-dose (LD) or placebo. METHODS: A systematic literature review was performed to find studies where spine surgery patients were given HD TXA (loading dose ≥30 mg/kg). Complication rates were pooled, and meta-analyses performed on outcomes of interest. Articles were evaluated for risk of bias and a strength of evidence assessment was given for each conclusion. RESULTS: Twenty three studies (n = 2331) were included. The pooled medical complication rate was 3.2% in pediatric patients, 8.2% in adults. Using lower dose TXA or placebo as the reference, meta-analysis showed no difference in medical complications (n = 1,723, OR 1.22 [95% CI, .78 to 1.22]; P = .388; I2 = 0%) or thrombotic events (n = 1158 patients, OR 1.27 [95% CI, .71 to 2.63]; P = .528; I2 = 0%). Compared to LD, HD TXA was associated with less intraoperative blood loss (823 patients, WMD = -285 [95% CI, -564 to -5.90]; P = .0454; I2 = 86%), fewer perioperative transfusions (n = 505, OR .28 [95% CI, .082 to .96]; P = .043; I2 = 76%) and lower perioperative transfusion volumes (n = 434, WMD -227.7 mL [95% CI, -377.3 to -78.02]; P = .0029; I2 = 0%). CONCLUSION: Compared to LD TXA or placebo, there is moderate evidence that HD is not associated with an increased risk of medical complications. Compared to LD, there is moderate evidence that HD reduces transfusion requirements. High-Dose TXA can be safely utilized in healthy patients undergoing major spine surgery.

Evaluation of the Clinical and Radiographic Degenerative Spondylolisthesis (CARDS) classification system as a guide to surgical technique selection.

BACKGROUND CONTEXT: The role of fusion in degenerative spondylolisthesis (DS) is controversial. The Clinical and Radiographic Degenerative Spondylolisthesis (CARDS) classification system was developed to assist surgeons in surgical technique selection based on individual patient characteristics. This system has not been clinically validated as a guide to surgical technique selection. PURPOSE: The purpose of this study was to determine if outcomes vary with different surgical techniques across the CARDS categories. STUDY DESIGN/SETTING: Prospective cohort study performed at one Swiss and one American spine center. PATIENT SAMPLE: Five hundred eight patients with DS undergoing surgical treatment. OUTCOME MEASURES: Core Outcomes Measure Index (COMI) at 3 months and 12 months postoperatively. METHODS: Patients undergoing surgery for DS were enrolled at 2 institutions and classified according to the CARDS system using dynamic radiographs. The Core Outcome Measure Index (COMI) was completed preoperatively, and 3 and 12 months postoperatively. Surgical technique was classified as uninstrumented (decompression alone or decompression with uninstrumented fusion) or instrumented (decompression with pedicle screw instrumentation with or without interbody fusion). Unadjusted analyses and mixed effect models compared COMI scores between the two surgery technique groups (uninstrumented vs instrumented), stratified by CARDS category over time. Reoperation rates were also compared between the surgery technique groups stratified by CARDS category. Partial funding was given through NASS grant for clinical research. RESULTS: Five hundred five out of 508 patients enrolled in the study had sufficient data to be classified according to CARDS. Seven percent were classified as CARDS A, 28% as CARDS B, 48% as CARDS C, and 17% as CARDS D (CARDS A most "stable," CARDS D least "stable"). One hundred and thirty-three patients (26%) underwent decompression alone, 30 (6%) underwent decompression and uninstrumented fusion, 42 (8%) underwent decompression and posterolateral instrumented fusion, and 303 (60%) underwent decompression with posterolateral and interbody instrumented fusion. Patients in the least "stable" categories tended to be less likely to be treated with an uninstrumented technique (CARDS D 19% vs 32% for the other categories, p=.10). There were no significant differences in 3 or 12-month COMI scores between surgical technique groups stratified by CARDS category in the unadjusted or adjusted analyses. In the unadjusted analyses, there was a trend towards less improvement in 12-month COMI change score in the CARDS D patients in the uninstrumented group compared to the instrumented group (-2.7 vs -4.1, p=.10). Reoperation rates were not significantly different between the surgical technique groups stratified by CARDS category. CONCLUSIONS: In general, outcomes for uninstrumented and instrumented surgical techniques were similar across the CARDS categories. Surgeons likely took factors included in CARDS into account during surgical technique selection. This resulted in a low number of CARDS D (n=15) patients being treated with uninstrumented techniques, which limited the statistical power of this analysis. As such, this study does not validate CARDS as a useful classification system for surgical technique selection in DS.

Female Sex and Supine Proximal Lumbar Lordosis Are Associated With the Size of the LLIF "Safe Zone" at L4-L5.

STUDY DESIGN: Retrospective chart review. OBJECTIVE: Identify demographic and sagittal alignment parameters that are independently associated with femoral nerve position at the L4-L5 disk space. SUMMARY OF BACKGROUND DATA: Iatrogenic femoral nerve or lumbar plexus injury during lateral lumbar interbody fusion (LLIF) can result in neurological complications. The LLIF "safe zone" is the anterior half to two third of the disk space. However, femoral nerve position varies and is inconsistently identifiable on magnetic resonance imaging. The safe zone is also narrowest at L4-L5. METHODS: An analysis of patients with symptomatic lumbar spine pathology and magnetic resonance imaging with a visibly identifiable femoral nerve evaluated at a single large academic spine center from January 1, 2017, to January 8, 2020, was performed. Exclusion criteria were transitional anatomy, severe hip osteoarthritis, coronal deformity with cobb >10 degrees, > grade 1 spondylolisthesis at L4-L5 and anterior migration of the psoas.Standing and supine lumbar lordosis (LL) and its proximal (L1-L4) and distal (L4-S1) components were measured. Femoral nerve position on sagittal imaging was then measured as a percentage of the L4 inferior endplate. A stepwise multivariate linear regression of sagittal alignment and LL parameters was then performed. Data are written as estimate, 95% CI. RESULTS: Mean patient age was 58.2±14.7 years, 25 (34.2%) were female and 26 (35.6%) had a grade 1 spondylolisthesis. Mean femoral nerve position was 26.6±10.3% from the posterior border of L4. Female sex (-6.6, -11.1 to -2.1) and supine proximal lumbar lordosis (0.4, 0.1-0.7) were independently associated with femoral nerve position. CONCLUSIONS: Patient sex and proximal LL can serve as early indicators of the size of the femoral nerve safe zone during a transpsoas LLIF approach at L4-L5.

Identification of cross-country skiing movement patterns using micro-sensors.

This study investigated the potential of micro-sensors for use in the identification of the main movement patterns used in cross-country skiing. Data were collected from four elite international and four Australian athletes in Europe and in Australia using a MinimaxX™ unit containing accelerometer, gyroscope and GPS sensors. Athletes performed four skating techniques and three classical techniques on snow at moderate velocity. Data from a single micro-sensor unit positioned in the centre of the upper back was sufficient to visually identify cyclical movement patterns for each technique. The general patterns for each technique were identified clearly across all athletes while at the same time distinctive characteristics for individual athletes were observed. Differences in speed, snow condition and gradient of terrain were not controlled in this study and these factors could have an effect on the data patterns. Development of algorithms to process the micro-sensor data into kinematic measurements would provide coaches and scientists with a valuable performance analysis tool. Further research is needed to develop such algorithms and to determine whether the patterns are consistent across a range of different speeds, snow conditions and terrain, and for skiers of differing ability.

Acute development of spinal lumbar synovial facet cyst within 1 week after lumbar decompression: illustrative case.

BACKGROUND: Synovial facet cysts can sometimes develop in patients with lumbar spinal stenosis after decompressive laminectomy. The etiology of spinal lumbar synovial cysts is still unclear, but their formation is associated with underlying spinal instability, facet joint arthropathy, and degenerative spondylolisthesis. OBSERVATIONS: A 61-year-old-male patient presented with neurogenic claudication due to lumbar spinal stenosis. Radiographic studies showed grade I spondylolisthesis and radiological predictors of delayed spinal instability. He underwent lumbar decompression and shortly thereafter developed spinal instability and recurrent symptoms, with formation of a new spinal lumbar synovial facet cyst. He required revisional decompression, cyst excision, and posterolateral spinal fusion for definitive treatment. LESSONS: The literature reports postoperative spinal instability in up to one-third of patients with lumbar spinal stenosis and stable degenerative spondylolisthesis who undergo decompressive laminectomy. Close radiographic monitoring and early advanced imaging may be prudent in this patient population if they develop new postoperative neurological symptoms and show radiographic predictors of instability on preoperative imaging. Posterolateral spinal fusion with instrumentation should be considered in addition to lumbar decompression in this select group of patients who demonstrate radiographic predictors of delayed spinal instability if they are medically capable of tolerating a spinal fusion procedure.

Worldwide Web: High Venom Potency and Ability to Optimize Venom Usage Make the Globally Invasive Noble False Widow Spider Steatoda nobilis (Thorell, 1875) (Theridiidae) Highly Competitive against Native European Spiders Sharing the Same Habitats.

Venom compositions include complex mixtures of toxic proteins that evolved to immobilize/dissuade organisms by disrupting biological functions. Venom production is metabolically expensive, and parsimonious use is expected, as suggested by the venom optimisation hypothesis. The decision-making capacity to regulate venom usage has never been demonstrated for the globally invasive Noble false widow Steatoda nobilis (Thorell, 1875) (Theridiidae). Here, we investigated variations of venom quantities available in a wild population of S. nobilis and prey choice depending on venom availability. To partially determine their competitiveness, we compared their attack rate success, median effective dose (ED50) and lethal dose (LD50), with four sympatric synanthropic species: the lace webbed spider Amaurobius similis, the giant house spider Eratigena atrica, the missing sector orb-weaver Zygiella x-notata, and the cellar spider Pholcus phalangioides. We show that S. nobilis regulates its venom usage based on availability, and its venom is up to 230-fold (0.56 mg/kg) more potent than native spiders. The high potency of S. nobilis venom and its ability to optimize its usage make this species highly competitive against native European spiders sharing the same habitats.

Diet Breadth Mediates the Prey Specificity of Venom Potency in Snakes.

Venoms are best known for their ability to incapacitate prey. In predatory groups, venom potency is predicted to reflect ecological and evolutionary drivers relating to diet. While venoms have been found to have preyspecific potencies, the role of diet breadth on venom potencies has yet to be tested at large macroecological scales. Here, using a comparative analysis of 100 snake species, we show that the evolution of prey-specific venom potencies is contingent on the breadth of a species' diet. We find that while snake venom is more potent when tested on species closely related to natural prey items, we only find this prey-specific pattern in species with taxonomically narrow diets. While we find that the taxonomic diversity of a snakes' diet mediates the prey specificity of its venom, the species richness of its diet was not found to affect these prey-specific potency patterns. This indicates that the physiological diversity of a species' diet is an important driver of the evolution of generalist venom potencies. These findings suggest that the venoms of species with taxonomically diverse diets may be better suited to incapacitating novel prey species and hence play an important role for species within changing environments.

Patient-Reported Allergies, a Marker of Preoperative Pain and Disability in Elective Spine Surgery.

STUDY DESIGN: Retrospective review. OBJECTIVE: Previous literature demonstrates mixed results regarding the relationship between patient-reported allergies and pain, function, and satisfaction scores. The objective of this study was to investigate the correlation between patient-reported allergies and preoperative Oswestry Disability Index (ODI), Neck Disability Index (NDI), and Patient-Reported Outcomes Measurement System (PROMIS) scores. METHODS: All patients undergoing elective cervical, lumbar procedures between May 2017 and October 2018 were included. Baseline demographic information was recorded, as well as all reported allergies or adverse reactions. Preoperative PROMIS, ODI, and NDI scores were recorded. Hierarchical multiple linear regressions were used to assess the relationship between total number of allergies and the preoperative pain and function scores. RESULTS: A total of 570 patients were included (476 lumbar, 94 cervical). The mean number of allergies reported was 1.89 ± 2.32. The mean preoperative ODI and NDI scores were 46.39 ± 17.67 and 43.47 ± 16.51, respectively. The mean preoperative PROMIS Physical Health and PROMIS Mental Health scores were 37.21 ± 6.54 and 43.89 ± 9.26, respectively. Hierarchical multiple linear regression showed that total number of reported allergies shared a statistically significant negative relationship with all of the following scores: ODI (B = 0.83, P = .02), NDI (B = 1.45, P = .02), PROMIS Physical Health (B = -0.29, P = .013), and PROMIS Mental Health (B = -0.38, P = .024). CONCLUSIONS: Patient-reported allergies share a statistically significant negative relationship with preoperative pain and function scores; as patients have increasing total number of allergies, the ODI/NDI scores become worse (increase) and the PROMIS scores become worse (decrease).

Keys to diagnosis and management of spinal epidural abscesses: 9 years of institutional experience.

OBJECTIVE: Spinal epidural abscesses (SEA's) are a challenge to diagnose, particularly if there are non-contiguous (skip) lesions. There is also limited data to predict which patients can be treated with antibiotics alone and which require surgery. We sought to assess which demographics, clinical and laboratory findings can guide both diagnosis and management of SEA's. METHODS: All patients with SEA (ICD9 324.1, ICD10 G06.1) between April 2011-May 2019 at a single tertiary center were included. A retrospective EMR review was completed. Patient and disease characteristics were compared using appropriate statistical tests. RESULTS: 108 patients underwent initial surgical treatment versus 105 that were treated medically initially; 22 (21 %) of those failed medical management. Patients who failed medical management had significantly higher CRP, longer symptom duration, and had higher rates of concurrent non-spinal infections. 9% of patients had skip lesions. Patients with skip lesions had significantly higher WBC, ESR, as well as higher rates of bacteremia and concurrent non-spinal infections. Demographic characteristics and proportion with IVDU, smoking, malignancy, and immunosuppression were similar among the three treatment groups. CONCLUSIONS: 21 % of SEA patients failed initial medical management; they had significantly greater CRP, longer symptom duration, more commonly had neurologic deficits, and concurrent non-spinal infections. 9% of patients had skip lesions; they had significantly higher WBC, ESR, rates of bacteremia and infections outside the spine. These variables may guide diagnostic imaging, and identify those at risk of failing of medical management, and therefore require more involved clinical evaluation, and consideration for surgical intervention.

Percutaneous Doxycycline Foam Injections: Novel Treatment Method for Vertebral Aneurysmal Bone Cysts.

Aneurysmal bone cysts (ABCs) are among the most aggressive benign bone tumors, often occurring in both long bones and the spine. Treatment remains controversial as recurrence rates continue to be high. Treatment options include curettage with or without bone grafting, arterial embolization, en block resection with or without instrumentation or arthrodesis, radiation, and intralesional drug injections (steroids, calcitonin, doxycycline). We present the case of a patient with a thoracic vertebral ABC who underwent 2 rounds of doxycycline foam percutaneous injections. At the 1-year follow up appointment, all symptoms had been resolved. Repeat computed tomography and magnetic resonance imaging demonstrated that the ABC had nearly filled in completely with new bone. Our case demonstrates successful use of this percutaneous, less invasive method in the management of vertebral ABCs.

Using the Teacher IRAP (T-IRAP) interactive computerized programme to teach complex flexible relational responding with children with diagnosed autism spectrum disorder.

The research used an alternating-treatments design to compare relational responding for five children with diagnosed autism spectrum disorder (ASD) in two teaching conditions. Both conditions used applied behavior analysis; one was usual tabletop teaching (TT), and one was an interactive computerized teaching program, the Teacher-Implicit Relational Assessment Programme (T-IRAP; Kilroe, Murphy, Barnes-Holmes, & Barnes-Holmes, Behavioral Development Bulletin, 19(2), 60-80, 2014). Relational skills targeted were coordination (same/different), with nonarbitrary and arbitrary stimuli. Participants' relational learning outcomes were compared in terms of speed of responding and accuracy (percentage correct) in T-IRAP and TT conditions. Results showed significantly increased speed for all five participants during T-IRAP teaching across all procedures; however, accuracy was only marginally increased during T-IRAP. Pre- and posttraining comparison of participant scores on the Peabody Picture Vocabulary Test, Fourth Edition (Dunn & Dunn, 2007), and the Kaufman Brief Intelligence Test (Kaufman & Kaufman, 1990) was conducted. An improvement in raw scores on both measures was evident for one participant who learned complex arbitrary relations; no changes were shown for participants who learned only basic nonarbitrary relations.

A 5-Year Review of Hospital Costs and Reimbursement in the Surgical Management of Degenerative Spondylolisthesis.

BACKGROUND: To evaluate charges, expenses, reimbursement, and hospital margins with noninstrumented posterolateral fusion in situ (PLF), posterolateral fusion with pedicle screws (PPS), and PPS with interbody device (PLIF) in degenerative spondylolisthesis with spinal stenosis. METHODS: A retrospective chart review was performed from 2010 to 2014 based on ICD-9 diagnoses of degenerative spondylolisthesis with spinal stenosis in patients undergoing single-level fusions. All charges, expenses, reimbursement, and margins were obtained through financial auditing. A multivariate linear regression model was used to compare demographics, charges, etc. A 1-way analysis of variance with Tukey post hoc analysis was used to analyze reimbursements and margins based upon insurances. RESULTS: Two hundred thirty-three patients met inclusion criteria. The overall charges and expenses for PLF were significantly less compared to both types of instrumented fusions (P < .0001). Medicare and private insurance were the most common insurance types; Medicare and private insurance mean reimbursements for PLF were $36,903 and $47,086, respectively; for PPS, $37,450 and $53,851, and for PLIF $40,171 and $51,640. Hospital margins for PPS and PLIF in Medicaid patients were negative (-$3,702 and -$6,456). Hospital margins were largest for both worker's compensation and private insurance patients in all fusion groups. Hospital margins with Medicare for PLF, PPS, and PLIF were $24,347, $19,205, and $23,046, respectively. Hospital margins for private insurance for PLF, PPS, and PLIF were $37,569, $36,834, and $33,134, respectively. CONCLUSIONS: As more instrumentation is used, the more it costs both the hospital and the insurance companies; hospital margins did not increase correspondingly. CLINICAL RELEVANCE: Improved understanding of related costs and margins associated with lumbar fusions to help transition to more cost effective spine centers.

Reducing Radiation and Lowering Costs With a Standardized Care Pathway for Nonoperative Thoracolumbar Fractures.

STUDY DESIGN: Retrospective observational study. OBJECTIVE: There is marked variation in the management of nonoperative thoracolumbar (TL) compression and burst fractures. This was a quality improvement study designed to establish a standardized care pathway for TL fractures treated with bracing, and to then evaluate differences in radiographs, length of stay (LOS), and cost before and after the pathway. METHODS: A standardized pathway was established for management of nonoperative TL burst and compression fractures (AOSpine classification type A1-A4 fractures). Bracing, radiographs, costs, complications, and LOS before and after pathway adoption were analyzed. Differences between the neurosurgery and orthopedic spine services were compared. RESULTS: Between 2012 and 2015, 406 nonoperative burst and compression TL fractures were identified. A total of 183 (45.1%) were braced, 60.6% with a custom-made thoracolumbosacral orthosis (TLSO) and 39.4% with an off-the-shelf TLSO. The number of radiographs significantly reduced after initiation of the pathway (3.23 vs 2.63, P = .010). A total of 98.6% of braces were custom-made before the pathway; 69.6% were off-the-shelf after the pathway. The total cost for braced patients after pathway adoption decreased from $10 462.36 to $8928.58 (P = .078). Brace-associated costs were significantly less for off-the-shelf TSLO versus custom TLSO ($1352.41 vs $3719.53, respectively, P < .001). The mean LOS and complication rate did not change significantly following pathway adoption. The orthopedic spine service braced less frequently than the neurosurgery service (40.7% vs 52.2%, P = .023). CONCLUSIONS: Standardized care pathways can reduce cost and radiation exposure without increasing complication rates in nonoperative management of thoracolumbar compression and burst fractures.

Development and validation of a method to directly measure the cable force during the hammer throw.

The development of cable force during hammer-throw turns is crucial to the throw distance. In this paper, we present a method that is capable of measuring cable force in real time and, as it does not interfere with technique, it is capable of providing immediate feedback to coaches and athletes during training. A strain gauge was mounted on the wires of three hammers to measure the tension in the wire and an elite male hammer thrower executed three throws with each hammer. The output from the gauges was recorded by a data logger positioned on the lower back of the thrower. The throws were captured by three high-speed video cameras and the three-dimensional position of the hammer's head was determined by digitizing the images manually. The five best throws were analysed. The force acting on the hammer's head was calculated from Newton's second law of motion and this was compared with the force measured via the strain gauge. Qualitatively the time dependence of the two forces was essentially the same, although the measured force showed more detail in the troughs of the force-time curves. Quantitatively the average difference between the measured and calculated forces over the five throws was 76 N, which corresponds to a difference of 3.8% for a cable force of 2000 N.

Full course macro-kinematic analysis of a 10 km classical cross-country skiing competition.

In this study micro-sensors were employed to analyse macro-kinematic parameters during a classical cross-country skiing competition (10 km, 2-lap). Data were collected from eight male participants during the Australian championship competition wearing a single micro-sensor unit (MinimaxX™, S4) positioned on their upper back. Algorithms and visual classification were used to identify skiing sub-techniques and calculate velocities, cycle lengths (CL) and cycle rates (CR) over the entire course. Double poling (DP) was the predominant cyclical sub-technique utilised (43 ± 5% of total distance), followed by diagonal stride (DS, 16 ± 4%) and kick double poling (KDP, 5 ± 4%), with the non-propulsive Tuck technique accounting for 24 ± 4% of the course. Large within-athlete variances in CL and CR occurred, particularly for DS (CV% = 25 ± 2% and CV% = 15 ± 2%, respectively). For all sub-techniques the mean CR on both laps and for the slower and faster skiers were similar, while there was a trend for the mean velocities in all sub-techniques by the faster athletes to be higher. Overall velocity and mean DP-CL were significantly higher on Lap 1, with no significant change in KDP-CL or DS-CL between laps. Distinct individual velocity thresholds for transitions between sub-techniques were observed. Clearly, valuable insights into cross-country skiing performance can be gained through continuous macro-kinematic monitoring during competition.

Increased Complications in Trapeziectomy With Ligament Reconstruction and Tendon Interposition Compared With Trapeziectomy Alone.

BACKGROUND: In the treatment of basal joint arthritis of the thumb, recent studies suggest equivalent outcomes with regard to long-term pain, mobility, and strength, in patients undergoing either trapeziectomy alone or trapeziectomy with ligament reconstruction and tendon interposition (LRTI). The goal of this study was to investigate risk factors for complications in carpometacarpal (CMC) arthroplasty. METHODS: We conducted a retrospective chart review of 5 surgeons at a single institution performing CMC arthroplasties from November 2006 to November 2012. A total of 200 thumbs in 179 patients underwent simple trapeziectomy with or without LRTI and with or without Kirschner wire stabilization, or a Weilby procedure. The average follow-up was 11.6 months (range = 1-69 months). Data collection included sex, age, history of smoking or diabetes, and any other surgeries performed on the hand at the time of arthroplasty. Furthermore, we collected outcomes involving any adverse events, paying attention to those necessitating reoperation, antibiotics, or those who developed complex regional pain syndrome. RESULTS: Seventy hands had a postoperative complication. Ten of these complications were considered major, defined as requiring antibiotics, reoperation, or other aggressive interventions. On multivariate analysis, risk of total complications was significantly greater only in patients undergoing either trapeziectomy with LRTI or Weilby procedure in comparison with trapeziectomy with K-wire stabilization (odds ratio = 4.30 and 6.73, respectively). CONCLUSIONS: Patients undergoing trapeziectomy with LRTI or Weilby had a greater incidence of reported complications when compared with trapeziectomy alone. These results suggest an advantage of simple trapeziectomy; however, further study is warranted.

Using micro-sensor data to quantify macro kinematics of classical cross-country skiing during on-snow training.

Micro-sensors were used to quantify macro kinematics of classical cross-country skiing techniques and measure cycle rates and cycle lengths during on-snow training. Data were collected from seven national level participants skiing at two submaximal intensities while wearing a micro-sensor unit (MinimaxX™). Algorithms were developed identifying double poling (DP), diagonal striding (DS), kick-double poling (KDP), tucking (Tuck), and turning (Turn). Technique duration (T-time), cycle rates, and cycle counts were compared to video-derived data to assess system accuracy. There was good reliability between micro-sensor and video calculated cycle rates for DP, DS, and KDP, with small mean differences (Mdiff% = -0.2 ± 3.2, -1.5 ± 2.2 and -1.4 ± 6.2) and trivial to small effect sizes (ES = 0.20, 0.30 and 0.13). Very strong correlations were observed for DP, DS, and KDP for T-time (r = 0.87-0.99) and cycle count (r = 0.87-0.99), while mean values were under-reported by the micro-sensor. Incorrect Turn detection was a major factor in technique cycle misclassification. Data presented highlight the potential of automated ski technique classification in cross-country skiing research. With further refinement, this approach will allow many applied questions associated with pacing, fatigue, technique selection and power output during training and competition to be answered.