Health-seeking behaviors, management practices, and return to play decisions after an ankle sprain in netball: An international cross-sectional survey of 1592 non-elite netballers.

OBJECTIVES: Evaluate if non-elite netballers sought health care, treatments received, and return-to-play decisions after an ankle sprain, including intercountry differences. DESIGN: Cross-sectional survey. METHODS: Non-elite netballers aged >14 years were recruited from Australia, United Kingdom, and New Zealand. Participants completed an online survey regarding their last ankle sprain and were queried regarding health care sought, health professionals consulted, treatments received, time missed, and return-to-play clearance. Data were described using number (proportion) for the overall cohort and countries. Between-country differences in health care use were compared using chi-square tests. Descriptive statistics were presented for management practices. RESULTS: We received 1592 responses from Australian (n = 846), United Kingdom (n = 454), and New Zealand (n = 292) netballers. Three in five (n = 951, 60 %) sought health care. Of those, most consulted a physiotherapist (n = 728, 76 %), received strengthening exercises (n = 771, 81 %), balance exercises (N = 665, 70 %) and taping (n = 636, 67 %). Few received return-to-play clearance (n = 362, 23 %). Comparing countries, fewer United Kingdom netballers sought health care than Australian and New Zealand netballers (Australia: 60 % vs United Kingdom: 53 % vs New Zealand: 68 %, p < 0.001), consulted a physiotherapist (Australia: 79 %, United Kingdom: 63 %, New Zealand: 87 %), received strengthening (Australia: 84 %, United Kingdom: 73 %, New Zealand: 84 %) or balance exercises (Australia: 71 %, United Kingdom: 60 %, New Zealand: 80 %) or taping (Australia: 74 %, United Kingdom: 39 %, New Zealand: 82 %). More Australian netballers returned to play within 1-7 days (Australia: 25 %, United Kingdom: 15 %, New Zealand: 21 %) and fewer United Kingdom netballers received return-to-play clearance (Australia: 28 %, United Kingdom: 10 %, New Zealand: 28 %). CONCLUSIONS: Health-seeking behaviours are adopted by some, but not all netballers after an ankle sprain. For those who sought care, most consulted a physiotherapist and were prescribed exercise-based interventions and external ankle support, but few received return-to-play clearance. Comparing countries, United Kingdom netballers had lower health-seeking behaviours and received less best-practice management than Australian and New Zealand netballers.

Do biomechanical foot-based interventions reduce patellofemoral joint loads in adults with and without patellofemoral pain or osteoarthritis? A systematic review and meta-analysis.

OBJECTIVE: To evaluate the effects of biomechanical foot-based interventions (eg, footwear, insoles, taping and bracing on the foot) on patellofemoral loads during walking, running or walking and running combined in adults with and without patellofemoral pain or osteoarthritis. DESIGN: Systematic review with meta-analysis. DATA SOURCES: MEDLINE, CINAHL, SPORTdiscus, Embase and CENTRAL. ELIGIBILITY CRITERIA FOR SELECTING STUDIES: English-language studies that assessed effects of biomechanical foot-based interventions on peak patellofemoral joint loads, quantified by patellofemoral joint pressure, reaction force or knee flexion moment during gait, in people with or without patellofemoral pain or osteoarthritis. RESULTS: We identified 22 footwear and 11 insole studies (participant n=578). Pooled analyses indicated low-certainty evidence that minimalist footwear leads to a small reduction in peak patellofemoral joint loads compared with conventional footwear during running only (standardised mean difference (SMD) (95% CI) = -0.40 (-0.68 to -0.11)). Low-certainty evidence indicated that medial support insoles do not alter patellofemoral joint loads during walking (SMD (95% CI) = -0.08 (-0.42 to 0.27)) or running (SMD (95% CI) = 0.11 (-0.17 to 0.39)). Very low-certainty evidence indicated rocker-soled shoes have no effect on patellofemoral joint loads during walking and running combined (SMD (95% CI) = 0.37) (-0.06 to 0.79)). CONCLUSION: Minimalist footwear may reduce peak patellofemoral joint loads slightly compared with conventional footwear during running only. Medial support insoles may not alter patellofemoral joint loads during walking or running and the evidence is very uncertain about the effect of rocker-soled shoes during walking and running combined. Clinicians aiming to reduce patellofemoral joint loads during running in people with patellofemoral pain or osteoarthritis may consider minimalist footwear.

External Ankle Support and Ankle Biomechanics in Chronic Ankle Instability: Systematic Review and Meta-Analysis.

OBJECTIVE: To systematically review the literature to determine whether external ankle supports influence ankle biomechanics in participants with chronic ankle instability (CAI) during sport-related tasks. DATA SOURCES: A literature search of MEDLINE, SPORTDiscus, and CINAHL databases was conducted in November 2021. STUDY SELECTION: Included studies were randomized crossover or parallel-group controlled trials in which researchers assessed ankle biomechanics during landing, running, or change of direction in participants with CAI using external ankle supports compared with no support. DATA EXTRACTION: Two authors independently identified studies, extracted data, and assessed risk of bias (Cochrane risk-of-bias tool version 2) and quality of evidence (Grading of Recommendations Assessment, Development and Evaluation). Random-effects meta-analysis was used to compare between-groups mean differences with 95% CIs. Grading of Recommendations Assessment, Development and Evaluation recommendations were used to determine the certainty of findings. DATA SYNTHESIS: A total of 13 studies of low to moderate risk of bias were included. During landing, very low-grade evidence indicated external ankle supports reduce frontal-plane excursion (mean difference [95% CI] = -1.83° [-2.97°, -0.69°], P = .002), plantar-flexion angle at initial contact (-3.86° [-6.18°, -1.54°], P = .001), and sagittal-plane excursion (-3.45° [-5.00°, -1.90°], P < .001) but not inversion angle at initial contact (-1.00° [-3.59°, 1.59°], P = .45). During running, very low- to low-grade evidence indicated external ankle supports reduce sagittal-plane excursion (-5.21° [-8.59°, -1.83°], P = .003) but not inversion angle at initial contact (0.32° [-2.11°, 1.47°], P = .73), frontal-plane excursion (-1.31° [-3.24°, 0.63°], P = .19), or plantar-flexion angle at initial contact (-0.12° [-3.54°, 3.29°], P = .94). Studies investigating changes of direction were insufficient. CONCLUSIONS: Very low-grade evidence indicated external ankle supports reduce frontal-plane excursion but not inversion angle at initial contact in participants with CAI during landing. Limiting frontal-plane excursion may reduce ankle-sprain risk. Frontal-plane ankle kinematics were not influenced by external ankle supports during running. Sagittal-plane reductions were observed with external ankle supports during landing and running with low to very low certainty, but their influence on ankle-sprain risk is undetermined.

The effect of biomechanical foot-based interventions on patellofemoral joint loads during gait in adults with and without patellofemoral pain or osteoarthritis: a systematic review protocol.

BACKGROUND: Patellofemoral pain is highly prevalent across the lifespan, and a significant proportion of people report unfavourable outcomes years after diagnosis. Previous research has implicated patellofemoral joint loading during gait in patellofemoral pain and its sequelae, patellofemoral osteoarthritis. Biomechanical foot-based interventions (e.g., footwear, insoles, orthotics, taping or bracing) can alter patellofemoral joint loads by reducing motions at the foot that increase compression between the patella and underlying femur via coupling mechanisms, making them a promising treatment option. This systematic review will summarise the evidence about the effect of biomechanical foot-based interventions on patellofemoral joint loads during gait in adults with and without patellofemoral pain and osteoarthritis. METHODS: MEDLINE (Ovid), the Cumulative Index to Nursing and Allied Health Literature CINAHL, The Cochrane Central Register of Controlled Trials (CENTRAL), SPORTdiscus (EBSCO) and Embase (Ovid) will be searched. Our search strategy will include terms related to 'patellofemoral joint', 'loads' and 'biomechanical foot-based interventions'. We will include studies published in the English language that assess the effect of biomechanical foot-based interventions on patellofemoral joint loads, quantified by patellofemoral joint pressure, patellofemoral joint reaction force and/or knee flexion moment. Two reviewers will independently screen titles and abstracts, complete full-text reviews, and extract data from included studies. Two reviewers will assess study quality using the Revised Cochrane Risk of Bias (RoB 2) tool or the Cochrane Risk Of Bias In Non-Randomized Studies - of Interventions (ROBINS-I) tool. We will provide a synthesis of the included studies' characteristics and results. If three or more studies are sufficiently similar in population and intervention, we will pool the data to conduct a meta-analysis and report findings as standardised mean differences with 95% confidence intervals. If a meta-analysis cannot be performed, we will conduct a narrative synthesis of the results and produce forest plots for individual studies. DISCUSSION: This protocol outlines the methods of a systematic review that will determine the effect of biomechanical foot-based interventions on patellofemoral joint loads. Our findings will inform clinical practice by identifying biomechanical foot-based interventions that reduce or increase patellofemoral joint loads, which may aid the treatment of adults with patellofemoral pain and osteoarthritis. TRIAL REGISTRATION: Registered with PROSPERO on the 4th of May 2022 (CRD42022315207).

Does the Addition of Whole-Body Vibration Training Improve Postural Stability and Lower Limb Strength During Rehabilitation Following Anterior Cruciate Ligament Reconstruction: A Systematic Review With Meta-analysis.

OBJECTIVES: To investigate whether the addition of whole-body vibration therapy to standard rehabilitation improves postural stability and lower limb strength following anterior cruciate ligament (ACL) reconstruction. DATA SOURCES: A computer-based literature search of MEDLINE, AMED, SPORTDiscus, Embase, CINAHL, CENTRAL, and Physiotherapy Evidence Database (PEDro) included studies up to October 2019. MAIN RESULTS: Seven randomised controlled trials of moderate-to-high methodological quality involving 244 participants were included. Meta-analysis found statistically significant improvements in medial-lateral stability [standardized mean difference (SMD) = 0.50; 95% confidence interval (CI), 0.12-0.88] and overall stability (SMD = 0.60; 95% CI, 0.14-1.06) favoring whole-body vibration therapy, but effects were not significant for quadriceps strength (SMD = 0.24; 95% CI, -0.65 to 1.13), hamstring strength (SMD = 0.84; 95% CI, -0.05 to 1.72), lower limb strength (SMD = 0.76; 95% CI, -0.16 to 1.67), or anterior-posterior stability (SMD = 0.19; 95% CI, -0.39 to 0.76). CONCLUSIONS: The addition of whole-body vibration therapy to standard postoperative rehabilitation following ACL reconstruction does not appear to significantly improve lower limb strength and anterior-posterior stability but may improve medial-lateral and overall postural stability. We found small sample sizes in all included trials, statistical heterogeneity, and methodological quality concerns, including publication bias, suggesting that larger high-quality trials are likely to be influential in this field. Registration: PROSPERO 155531.

Water Flow in Single-Wall Nanotubes: Oxygen Makes It Slip, Hydrogen Makes It Stick.

Experimental measurements have reported ultrafast and radius-dependent water transport in carbon nanotubes which are absent in boron nitride nanotubes. Despite considerable effort, the origin of this contrasting (and fascinating) behavior is not understood. Here, with the aid of machine learning-based molecular dynamics simulations that deliver first-principles accuracy, we investigate water transport in single-wall carbon and boron nitride nanotubes. Our simulations reveal a large, radius-dependent hydrodynamic slippage on both materials, with water experiencing indeed a ≈5 times lower friction on carbon surfaces compared to boron nitride. Analysis of the diffusion mechanisms across the two materials reveals that the fast water transport on carbon is governed by facile oxygen motion, whereas the higher friction on boron nitride arises from specific hydrogen-nitrogen interactions. This work not only delivers a clear reference of quantum mechanical accuracy for water flow in single-wall nanotubes but also provides detailed mechanistic insight into its radius and material dependence for future technological application.

Sex differences in endurance exercise capacity and skeletal muscle lipid metabolism in mice.

Previous studies suggest that sex differences in lipid metabolism exist with females demonstrating a higher utilization of lipids during exercise, which is mediated partly by increased utilization of muscle triglycerides. However, whether these changes in lipid metabolism contribute directly to endurance exercise performance is unclear. Therefore, the objective of this study was to investigate the contribution of exercise substrate metabolism to sex differences in endurance exercise capacity (EEC) in mice. Male and female C57BL/6-NCrl mice were subjected to an EEC test until exhaustion on a motorized treadmill. The treadmill was set at a 10% incline, and the speed gradually increased from 10.2 m/min to 22.2 m/min at fixed intervals for up to 2.5 h. Tissues and blood were harvested in mice immediately following the EEC. A cohort of sedentary, non-exercised male and female mice were used as controls. Females outperformed males by ~25% on the EEC. Serum levels of both fatty acids and ketone bodies were ~50% higher in females at the end of the EEC. In sedentary female mice, skeletal muscle triglyceride content was significantly greater compared to sedentary males. Gene expression analysis demonstrated that genes involved in skeletal muscle fatty acid oxidation were significantly higher in females with no changes in genes associated with glucose uptake or ketone body oxidation. The findings suggest that female mice have a higher endurance exercise capacity and a greater ability to mobilize and utilize fatty acids for energy.

Current ankle sprain prevention and management strategies of netball athletes: a scoping review of the literature and comparison with best-practice recommendations.

BACKGROUND: Ankle sprains are the most commonly reported injury in netball. Approximately four in five netball athletes will sustain an ankle sprain, up to half will go on to sustain recurrent ankle sprains, and nine in ten report perceived ankle instability. Historically, prevention and management strategies of ankle sprains and injuries have been investigated for a variety of sports, however, no literature reviews have investigated these in netball athletes, or compared these with current best-practice within the literature. Therefore, this scoping review aims to understand how netball athletes currently prevent and manage ankle sprains and to compare these approaches with best-practice recommendations. METHODS: A literature search was conducted using MEDLINE, CINAHL, and SPORTDiscus databases using keywords to capture studies with data or information related to the prevention and management of ankle sprains and injuries in netball. RESULTS: The search strategy captured 982 studies across all databases, with 30 netball studies included in this scoping review. Studies suggest netball athletes are not commonly referred to health professionals, do not undertake adequate rehabilitation, and almost immediately return to court following an ankle sprain or injury. Current best-practices suggest injury prevention programs and external ankle support effectively reduce ankle sprains and injuries; however, poor compliance and implementation may be a significant barrier. Currently, there is a lack of evidence that netball-specific footwear reduces the risk of ankle sprains. CONCLUSION: The findings suggest netball athletes do not implement current best-practice prevention and management strategies following an ankle sprain. This is despite evidence of the effectiveness of injury prevention programs, external ankle support, and adequate rehabilitation in reducing ankle sprain rates. Current-best practice prevention and management of ankle sprains should be considered by clinicians, coaches, and athletes to reduce the prevalence and chronicity of ankle sprains in netball.

Machine learning potentials for complex aqueous systems made simple.

Simulation techniques based on accurate and efficient representations of potential energy surfaces are urgently needed for the understanding of complex systems such as solid-liquid interfaces. Here we present a machine learning framework that enables the efficient development and validation of models for complex aqueous systems. Instead of trying to deliver a globally optimal machine learning potential, we propose to develop models applicable to specific thermodynamic state points in a simple and user-friendly process. After an initial ab initio simulation, a machine learning potential is constructed with minimum human effort through a data-driven active learning protocol. Such models can afterward be applied in exhaustive simulations to provide reliable answers for the scientific question at hand or to systematically explore the thermal performance of ab initio methods. We showcase this methodology on a diverse set of aqueous systems comprising bulk water with different ions in solution, water on a titanium dioxide surface, and water confined in nanotubes and between molybdenum disulfide sheets. Highlighting the accuracy of our approach with respect to the underlying ab initio reference, the resulting models are evaluated in detail with an automated validation protocol that includes structural and dynamical properties and the precision of the force prediction of the models. Finally, we demonstrate the capabilities of our approach for the description of water on the rutile titanium dioxide (110) surface to analyze the structure and mobility of water on this surface. Such machine learning models provide a straightforward and uncomplicated but accurate extension of simulation time and length scales for complex systems.

Defect-Dependent Corrugation in Graphene.

Graphene's intrinsically corrugated and wrinkled topology fundamentally influences its electronic, mechanical, and chemical properties. Experimental techniques allow the manipulation of pristine graphene and the controlled production of defects which allows one to control the atomic out-of-plane fluctuations and thus tune graphene's properties. Here, we perform large scale machine learning-driven molecular dynamics simulations to understand the impact of defects on the structure of graphene. We find that defects cause significantly higher corrugation leading to a strongly wrinkled surface. The magnitude of this structural transformation strongly depends on the defect concentration and specific type of defect. Analyzing the atomic neighborhood of the defects reveals that the extent of these morphological changes depends on the preferred geometrical orientation and the interactions between defects. While our work highlights that defects can strongly affect graphene's morphology, it also emphasizes the differences between distinct types by linking the global structure to the local environment of the defects.

An accurate and transferable machine learning potential for carbon.

We present an accurate machine learning (ML) model for atomistic simulations of carbon, constructed using the Gaussian approximation potential (GAP) methodology. The potential, named GAP-20, describes the properties of the bulk crystalline and amorphous phases, crystal surfaces, and defect structures with an accuracy approaching that of direct ab initio simulation, but at a significantly reduced cost. We combine structural databases for amorphous carbon and graphene, which we extend substantially by adding suitable configurations, for example, for defects in graphene and other nanostructures. The final potential is fitted to reference data computed using the optB88-vdW density functional theory (DFT) functional. Dispersion interactions, which are crucial to describe multilayer carbonaceous materials, are therefore implicitly included. We additionally account for long-range dispersion interactions using a semianalytical two-body term and show that an improved model can be obtained through an optimization of the many-body smooth overlap of atomic positions descriptor. We rigorously test the potential on lattice parameters, bond lengths, formation energies, and phonon dispersions of numerous carbon allotropes. We compare the formation energies of an extensive set of defect structures, surfaces, and surface reconstructions to DFT reference calculations. The present work demonstrates the ability to combine, in the same ML model, the previously attained flexibility required for amorphous carbon [V. L. Deringer and G. Csányi, Phys. Rev. B 95, 094203 (2017)] with the high numerical accuracy necessary for crystalline graphene [Rowe et al., Phys. Rev. B 97, 054303 (2018)], thereby providing an interatomic potential that will be applicable to a wide range of applications concerning diverse forms of bulk and nanostructured carbon.

Importance and Nature of Short-Range Excitonic Interactions in Light Harvesting Complexes and Organic Semiconductors.

The singlet excitonic coupling between many pairs of chromophores is evaluated in three different light harvesting complexes (LHCs) and two organic semiconductors (amorphous and crystalline). This large database of structures is used to assess the relative importance of short-range (exchange, overlap, orbital) and long-range (Coulombic) excitonic coupling. We find that Mulliken atomic transition charges can introduce systematic errors in the Coulombic coupling and that the dipole-dipole interaction fails to capture the true Coulombic coupling even at intermolecular distances of up to 50 Å. The non-Coulombic short-range contribution to the excitonic coupling is found to represent up to ∼70% of the total value for molecules in close contact, while, as expected, it is found to be negligible for dimers not in close contact. For the face-to-face dimers considered here, the sign of the short-range interaction is found to correlate with the sign of the Coulombic coupling, i.e. reinforcing it when it is already strong. We conclude that for molecules in van der Waals contact the inclusion of short-range effects is essential for a quantitative description of the exciton dynamics.

Structure-Dynamics Relation in Physically-Plausible Multi-Chromophore Systems.

We study a large number of physically-plausible arrangements of chromophores, generated via a computational method involving stochastic real-space transformations of a naturally-occurring "reference" structure, illustrating our methodology using the well-studied Fenna-Matthews-Olson complex (FMO). To explore the idea that the natural structure has been tuned for efficient energy transport, we use an atomic transition charge method to calculate the excitonic couplings of each generated structure and a Lindblad master equation to study the quantum transport of an exciton from a "source" to a "drain" chromophore. We find significant correlations between structure and transport efficiency: High-performing structures tend to be more compact and, among those, the best structures display a certain orientation of the chromophores, particularly the chromophore closest to the source-to-drain vector. We conclude that, subject to reasonable, physically motivated constraints, the FMO complex is highly attuned to the purpose of energy transport, partly by exploiting these structural motifs.

Safety and efficacy in parous women of a 52-mg levonorgestrel-medicated intrauterine device: a 7-year randomized comparative study with the TCu380A.

OBJECTIVES: To compare rates of unintended pregnancy, method continuation and reasons for removal among women using the 52-mg levonorgestrel (daily release 20 microg) intrauterine device (LNG-IUD) or the copper T 380 A IUD (TCu380A). STUDY DESIGN: This was an open-label 7-year randomized controlled trial in 20 centres, 11 of which in China. Data on 1884 women with interval insertion of the LNG-IUD and 1871 of the TCu380A were analysed using life tables with 30-day intervals and Cox proportional hazards models. RESULTS: The cumulative 7-year pregnancy rate of the LNG-IUD was 0.5 (standard error 0.2) per 100, significantly lower than 2.5 (0.4) per 100 of the TCu380A, cumulative method discontinuation rates at 7 years were 70.6 (1.2) and 40.8 (1.3) per 100, respectively. Dominant reasons for discontinuing the LNG-IUD were amenorrhea (26.1 [1.3] per 100) and reduced bleeding (12.5 [1.1] per 100), particularly in Chinese women and, for the TCu380A, increased bleeding (9.9 [0.9] per 100), especially among non-Chinese women. Removal rates for pain were similar for the two intrauterine devices (IUDs). Cumulative rates of removal for symptoms compatible with hormonal side effects were 5.7 (0.7) and 0.4 (0.2) per 100 for the LNG-IUD and TCu380A, respectively, and cumulative losses to follow-up at 7 years were 26.0 (1.4) and 36.9 (1.3) per 100, respectively. CONCLUSION: The LNG-IUD and the TCu380A have very high contraceptive efficacy, with the LNG-IUD significantly higher than the TCu380A. Overall rates of IUD removals were higher among LNG-IUD users than TCu380A users. Removals for amenorrhea appeared culturally associated. IMPLICATIONS: The 52-mg LNG-IUD and the TCu380A have very high contraceptive efficacy through 7 years. As an IUD, the unique side effects of the LNG-IUD are reduced bleeding, amenorrhea and symptoms compatible with hormonal contraceptives.

The Juvenile Diabetes Research Foundation Network for Pancreatic Organ Donors with Diabetes (nPOD) Program: goals, operational model and emerging findings.

nPOD actively promotes a multidisciplinary and unbiased approach toward a better understanding of T1D and identify novel therapeutic targets, through its focus on the study of human samples. Unique to this effort is the coordination of collaborative efforts and real-time data sharing. Studies supported by nPOD are providing direct evidence that human T1D isa complex and heterogeneous disease, in which a multitude of pathogenic factors may be operational and may contribute to the onset of the disease. Importantly, the concept that beta cell destruction is almost completed and that the autoimmune process is almost extinguished soon after diagnosis is being challenged. nPOD investigators are exploring the hypothesis that beta cell dysfunction may also be a significant cause of hyperglycemia, at least around the time of diagnosis, and are uncovering novel molecules and pathways that are linked to the pathogenesis and etiology of human T1D. The validation of therapeutic targets is also a key component of this effort, with recent and future findings providing new strategic direction for clinical trials.

Increased complement activation in human type 1 diabetes pancreata.

OBJECTIVE: Evidence supporting an association between complement (C) and type 1 diabetes (T1D) includes the identification of C-fixing islet cell autoantibodies in T1D sera and genetic associations with the major histocompatibility complex III C4 region on chromosome 6. Therefore, we investigated whether C activation was present in pancreata from those with or at increased risk (positive for T1D associated autoantibodies) for T1D. RESEARCH DESIGN AND METHODS: Immunohistochemical techniques were used to measure the C degradation product C4d in organ donor pancreata from patients with T1D and type 2 diabetes and autoantibody-positive and autoantibody-negative subjects. RESULTS: Median C4d antigen density differed across the groups (P < 0.0001) and was highest in patients with T1D. C4d immunostaining localized to the blood vessel endothelium and extracellular matrix surrounding blood vessels and exocrine ducts. Receiver operating characteristic analysis resulted in 81.8% sensitivity and 94.4% specificity for C4d staining. CONCLUSIONS: These data suggest that C activation is occurring within pancreata from patients with T1D and C4d may be a biomarker for T1D.

Precision intrauterine contraception may significantly increase continuation of use: a review of long-term clinical experience with frameless copper-releasing intrauterine contraception devices.

OBJECTIVE: The purpose of this paper is to review the experience with the frameless, anchored, GyneFix copper-releasing intrauterine contraceptive devices (IUCDs/IUDs) (Contrel Europe, Belgium), and to demonstrate their high acceptability and low rate of discontinuation of use, which could contribute to current efforts that aim to reduce radically the high number of unintended pregnancies and induced abortions, particularly in young women. MATERIALS AND METHODS: This paper is based on studies that examined the differences in uterine volume and cavity size, related to age and parity, and on original clinical research data and practical experience with frameless copper IUDs, as well as on literature data on the IUD-endometrial cavity relationship of conventional IUDs, with special reference to side effects and user discontinuation. RESULTS: The mean transverse diameter in nulliparous and parous women is significantly less than the length of the transverse arm of the TCu380A IUD (ParaGard, Duramed, NY, USA) or the levonorgestrel intrauterine system (Mirena, Bayer, Germany). Small, frameless, flexible, and unidimensional copper IUDs appear to be well tolerated, with less impact on menstrual bleeding, resulting in low discontinuation rates when compared with standard-size conventional IUDs, which often result in increased expulsion rates, complaints of pain and erratic or increased menstrual bleeding, and subsequent high rates of discontinuation, particularly in young women. CONCLUSION: The unidimensional GyneFix IUDs fit the majority of uterine cavities. An IUD that fits is likely to result in increased tolerance and continued use of the method. As this would appeal to women, the logical result should be greater use of the method and fewer unintended pregnancies and induced abortions. Recommending the standard TCu380A (ParaGard) IUD or the Mirena levonorgestrel intrauterine system, primarily developed for use in parous women, for general use in nulliparous and adolescent women should be done with caution in the light of current scientific evidence, except if 3-D sonography indicates that the uterine cavity is sufficiently large.