Death due to sickle cell crisis: a case report.

Sickle cell disease (SCD) is the most common hereditary hemoglobinopathy worldwide. It results in characteristic acute and chronic findings on postmortem computed tomography (PMCT), macroscopic and microscopic examinations. While the diagnostic imaging and macroscopic features are not specific for SCD on their own, when coupled with microscopic features such as sickled erythrocytes and evidence of chronic venous congestion (i.e., Gamna-Gandy bodies), these clues can help alert forensic pathologists to the presence of SCD. Despite the prevalence of the disease and the constellation of findings alluded to above, SCD is not often explored in forensic pathology literature. This case demonstrates classic acute and chronic features of SCD on PMCT, macroscopic and microscopic examinations. It explores the pathophysiology leading to sudden and unexpected death in a person with SCD and possible pitfalls in attribution of cause of death.

Ankle proprioception in children with cerebral palsy.

PURPOSE: There is no established clinical standard to evaluate ankle proprioception in children with cerebral palsy (CP). This study compared ankle position sense of children with CP to age-matched children who are typically developing (TD). METHODS: Children aged 6-17 years participated (15 CP, 58 TD). Using a custom-built device, the ankle was passively rotated to two positions for 25 trials. Using a psychophysical forced-choice paradigm, participants indicated which position was more plantarflexed. A psychometric function was fitted to the response data to determine the just noticeable difference (JND) threshold and the associated uncertainty (random error) for ankle position sense. RESULTS: Median JND thresholds for the CP group were elevated (CP: 4.3°, TD: 3.0°). Three children with CP exceeded the 95th percentile of TD. No differences in random error were found. CONCLUSION: This method assessed ankle proprioception relative to norm data and identified position sense impairments in children with CP. Using this method can provide data on proprioceptive status in CP, augmenting the assessment of motor impairment.

Medial Gastrocnemius Muscle Properties of Children With Cerebral Palsy After Different Tone Treatments: A Pilot Study.

OBJECTIVE: Spasticity in children with cerebral palsy can be managed by a spectrum of approaches, from conservative therapy, to temporary botulinum toxin A injections, to permanent transection of sensory nerves with a selective dorsal rhizotomy. This pilot study investigated whether these three tone management approaches are associated with histological and biochemical properties of the medial gastrocnemius. DESIGN: A convenience sample of children with cerebral palsy undergoing gastrocnemius lengthening surgery was enrolled. Intraoperative biopsies were obtained from three individuals (one each: minimal tone treatment; frequent gastrocnemius botulinum toxin A injections; previous selective dorsal rhizotomy). All individuals had plantarflexor contractures, weakness, and impaired motor control before the biopsy. RESULTS: Differences between participants were observed for muscle fiber cross-sectional area, fiber type, lipid content, satellite cell density, and centrally located nuclei. The most pronounced difference was the abundance of centrally located nuclei in the botulinum toxin A participants (52%) compared with the others (3-5%). Capillary density, collagen area and content, and muscle protein content were similar across participants. CONCLUSIONS: Several muscle properties seemed to deviate from reported norms, although age- and muscle-specific references are sparse. Prospective studies are necessary to distinguish cause and effect and to refine the risks and benefits of these treatment options.

Variability in lower extremity motor function in spina bifida only partially associated with spinal motor level.

PURPOSE: Previous studies have found motor function to correlate with spinal motor level and, accordingly, individuals with spina bifida are frequently categorized clinically in this manner. The aim of the current study was to describe how lower extremity functions including strength, selective motor control, and mirror movements vary by motor level in children and young adults with spina bifida. METHODS: A single center, retrospective, cross-sectional, descriptive study using data collected in the National Spina Bifida Patient Registry and by a gait laboratory was performed. RESULTS: Seventy-seven individuals with spina bifida were included with the majority having myelomeningocele (59 lumbar, 18 sacral motor level). Lower extremity strength and selective motor control varied to a certain extent with motor level. However, 90% of individuals showed strength or weakness in at least one muscle group that was unexpected based on their motor level. Mirror movements did not clearly vary with motor level. CONCLUSION: Lower extremity strength, selective motor control, and mirror movements in individuals with spina bifida were not entirely predicted by motor level. This highlights the possible need for an improved spina bifida classification system that describes not only spinal motor level but more clearly defines a particular individual's functional motor abilities.

Freshwater unionid mussels threatened by predation of Round Goby (Neogobius melanostomus).

Indigenous freshwater mussels (Unionidae) are integral to riverine ecosystems, playing a pivotal role in aquatic food webs and providing ecological services. With populations on the decline worldwide, freshwater mussels are of conservation concern. In this study, we explore the propensity of the invasive Round Goby (Neogobius melanostomus) fish to prey upon indigenous freshwater mussels. First, we conducted lab experiments where Round Gobies were given the opportunity to feed on juvenile unionid mussels and macroinvertebrates, revealing rates and preferences of consumption. Several Round Gobies consumed whole freshwater mussels during these experiments, as confirmed by mussel counts and x-ray images of the fishes. Next, we investigated Round Gobies collected from stream habitats of the French Creek watershed, which is renowned for its unique and rich aquatic biodiversity. We developed a novel DNA metabarcoding method to identify the specific species of mussels consumed by Round Goby and provide a new database of DNA gene sequences for 25 indigenous unionid mussel species. Several of the fishes sampled had consumed indigenous mussels, including the Elktoe (non-endangered), Creeper (non-endangered), Long Solid (state endangered), and Rayed Bean (federally endangered) species. The invasive Round Goby poses a growing threat to unionid mussels, including species of conservation concern. The introduction of the invasive Round Goby to freshwaters of North America is shaping ecosystem transitions within the aquatic critical zone having widespread implications for conservation and management.

Presence and predictors of pain after orthopedic surgery and associated orthopedic outcomes in children with cerebral palsy.

While children with cerebral palsy (CP) may undergo 8-22 orthopedic surgeries in their lifetime, little is known about the associated pain. We aimed to assess the pain presence before and one year after lower extremity orthopedic surgery, predictors of pain presence at follow-up, and the association between pain and orthopedic outcomes related to surgery. This retrospective study included 86 children with CP (M age = 10.0 years, SD = 3.2; range = 4.1-17.3 years, Gross Motor Functional Classification System (GMFCS) level I-III) who underwent orthopedic surgery and had completed questionnaires at gait analyses before (M = 2.7 months; range = 0.0-5.7) and after surgery (M = 11.8 months; range = 9.0-14.9). Pain presence, location, and Pediatric Outcomes Data Collection Instrument (PODCI) scores were documented before and after surgery at gait analyses. Pain prevalence was 60% at baseline and 56% at follow-up. Significant predictors of pain presence at follow-up included (1) pain presence at baseline (range of odds ratios [OR] across any/all locations = 3.22 to 15.54), (2) older age (range of OR for any pain, back, knee, and foot pain = 1.24-1.26), (3) female sex (decreased OR for males for ankle pain = 0.12), (4) having hip surgery (decreased OR for foot pain = 0.20), and (5) lower GMFCS level (OR for foot pain = 0.41). Changes in PODCI Sports and Physical Function scores were associated with changes in hip and knee pain (P < .03); PODCI scores worsened for patients who had pain at both time points and improved for patients who had pain at baseline but not follow-up. Pain was present for over half of the participants before and after orthopedic surgery. Pain presence at follow-up was predicted by pain presence at baseline. Pain and functional outcomes were correlated at follow-up. Prospective studies examining perioperative pain experience and factors predicting pain outcomes are warranted.

Validation of the Gait Outcomes Assessment List questionnaire and caregiver priorities for individuals with cerebral palsy.

AIM: To expand upon previous validation of the Gait Outcomes Assessment List (GOAL) questionnaire in individuals with cerebral palsy (CP), to rank items by importance, and to summarize written-in (free text) goals. METHOD: For this cross-sectional study, the parent-version 5.0 of the GOAL was completed by 310 consecutive caregivers of 310 individuals aged 3 to 25 years with CP (189 males, 121 females; mean [SD] age: 10y [4y 2mo]; Gross Motor Function Classification System [GMFCS] levels I-IV) concurrent with a gait analysis. Distribution properties and validity were quantified using questionnaires, kinematics, and oxygen consumption. Items classified as at least 'difficult' to perform and 'very important' to improve were considered caregiver priorities and rank ordered. Free text goals were categorized. Results were summarized for everyone and by GMFCS level. RESULTS: Most scores were normally distributed. Validity was acceptable, with concurrent greater than construct validity. Among all 310 caregivers, fatigue was the highest priority, followed by gait pattern and appearance items. The rank of priorities varied by GMFCS level. Common free text goals included toileting independently as well as improved fine motor and ball sport skills. INTERPRETATION: The GOAL is a valid tool that can help prioritize goals across GMFCS levels I to IV. Identifying the top goals may improve shared decision-making and prioritize research for this sample.

Long-term functional outcomes after an external femoral derotation osteotomy in individuals with cerebral palsy.

BACKGROUND: It is unknown how a femoral derotation osteotomy (FDO) during childhood affects functional outcomes in adulthood among individuals with bilateral cerebral palsy (CP). RESEARCH QUESTIONS: How do long-term functional outcomes after an FDO compare to matched individuals who did not have an FDO? How do outcomes change over time? METHODS: We queried the gait laboratory database for individuals who underwent an external FDO in childhood and were currently ≥25 years old. Participants returned for a long-term analysis (gait, physical examination, functional tests, imaging, questionnaires). The matched non-FDO group included only individuals in Gross Motor Function Classification System levels I-II, yielding three groups (non-FDO I-II, FDO I-II, FDO III-IV). RESULTS: Sixty-one adults (11 non-FDO, 34 FDO I-II, 16 FDO III-IV) returned 13-25 years after baseline (non-FDO) or surgery (FDO). The non-FDO and FDO I-II groups were matched at baseline on most variables, except the FDO group had weaker hip abductors. At long-term, groups were similar on gait variables (median long-term hip rotation [primary outcome], non-FDO: -4°, FDO I-II: -4°, FDO III-IV: -5°), hip abduction test, fear of falling, and most pain measures despite anteversion being 29° greater in the non-FDO group. The FDO I-II group reported more falls than the non-FDO group. All groups improved on hip rotation, foot progression, and hip abductor strength. Speed and step length decreased/tended to decrease for all three groups. Hip abduction moment and gait deviation index did not change. Improvements in the FDO groups were maintained from short- to long-term. SIGNIFICANCE: These results challenge the notion that an FDO is necessary to correct mean stance hip rotation for higher functioning individuals since nearly identical results were achieved by adulthood in the non-FDO I-II group. However, an FDO provides improvement earlier and maintenance from short- to long-term. This should factor into the shared decision-making process.

Perceived Limitations of Walking in Individuals With Cerebral Palsy.

OBJECTIVE: Impairments associated with cerebral palsy (CP) can affect gait quality and limit activity and participation. The purpose of this study was to quantify (1) which of 6 factors (pain, weakness, endurance, mental ability, safety concerns, balance) were perceived to limit walking ability the most in individuals with CP and (2) whether age or Gross Motor Function Classification System (GMFCS) level is related to that perception. METHODS: This cross-sectional study queried data from a gait laboratory database. Perceived walking limitation was quantified using a 5-point Likert scale ("never" to "all of the time"). Included were 1566 children and adults (mean age = 10.9 y [SD = 6.8]; range = 3.0-72.1 y) with CP (GMFCS level I: 502; II: 564; III: 433; IV: 67). RESULTS: Patients or caregivers perceived balance to limit walking ability to the greatest extent, followed by endurance, weakness, safety, mental ability, and pain. Balance was perceived to always limit walking ability in 8%, 22%, 30%, and 34% of individuals in GMFCS levels I through IV, respectively. Endurance was perceived to always limit walking ability in 5%, 13%, 13%, and 27% of individuals in GMFCS levels I through IV, respectively. There were minor differences in the perceived extent of limitation caused by the factors by GMFCS level. Only weak associations between age and pain, mental ability, safety, and balance were observed (Spearman rho = -0.13 to 0.24). CONCLUSION: Patients or caregivers perceived decreased balance and endurance to most strongly limit walking ability. Efforts should be made to clinically track how both perceived and objective measures of these limiting factors change with age and intervention. IMPACT: Following a patient- and family-centered care model, therapy that places greater emphasis on balance and cardiovascular endurance may have the greatest effect on walking ability for individuals with CP. Future research should quantify which therapeutic, surgical, and pharmacologic interventions minimize these impairments and optimize activity and participation. LAY SUMMARY: Balance and endurance are perceived to be the greatest factors limiting walking in people with CP. If you have CP, your physical therapist might emphasize balance and cardiovascular endurance to improve your walking ability.

Peak grain forecasts for the US High Plains amid withering waters.

Irrigated agriculture contributes 40% of total global food production. In the US High Plains, which produces more than 50 million tons per year of grain, as much as 90% of irrigation originates from groundwater resources, including the Ogallala aquifer. In parts of the High Plains, groundwater resources are being depleted so rapidly that they are considered nonrenewable, compromising food security. When groundwater becomes scarce, groundwater withdrawals peak, causing a subsequent peak in crop production. Previous descriptions of finite natural resource depletion have utilized the Hubbert curve. By coupling the dynamics of groundwater pumping, recharge, and crop production, Hubbert-like curves emerge, responding to the linked variations in groundwater pumping and grain production. On a state level, this approach predicted when groundwater withdrawal and grain production peaked and the lag between them. The lags increased with the adoption of efficient irrigation practices and higher recharge rates. Results indicate that, in Texas, withdrawals peaked in 1966, followed by a peak in grain production 9 y later. After better irrigation technologies were adopted, the lag increased to 15 y from 1997 to 2012. In Kansas, where these technologies were employed concurrently with the rise of irrigated grain production, this lag was predicted to be 24 y starting in 1994. In Nebraska, grain production is projected to continue rising through 2050 because of high recharge rates. While Texas and Nebraska had equal irrigated output in 1975, by 2050, it is projected that Nebraska will have almost 10 times the groundwater-based production of Texas.

Nitrogen futures in the shared socioeconomic pathways 4.

Humanity's transformation of the nitrogen cycle has major consequences for ecosystems, climate and human health, making it one of the key environmental issues of our time. Understanding how trends could evolve over the course of the 21st century is crucial for scientists and decision-makers from local to global scales. Scenario analysis is the primary tool for doing so, and has been applied across all major environmental issues, including nitrogen pollution. However, to date most scenario efforts addressing nitrogen flows have either taken a narrow approach, focusing on a singular impact or sector, or have not been integrated within a broader scenario framework - a missed opportunity given the multiple environmental and socio-economic impacts that nitrogen pollution exacerbates. Capitalizing on our expanding knowledge of nitrogen flows, this study introduces a framework for new nitrogen-focused narratives based on the widely used Shared Socioeconomic Pathways that include all the major nitrogen-polluting sectors (agriculture, industry, transport and wastewater). These new narratives are the first to integrate the influence of climate and other environmental pollution control policies, while also incorporating explicit nitrogen-control measures. The next step is for them to be used as model inputs to evaluate the impact of different nitrogen production, consumption and loss trajectories, and thus advance understanding of how to address environmental impacts while simultaneously meeting key development goals. This effort is an important step in assessing how humanity can return to the planetary boundary of this essential element over the coming century.

Association of Knee Pain and Crouch Gait in Individuals With Cerebral Palsy.

BACKGROUND: Crouch gait (ie, excessive knee flexion) is commonly seen in patients with cerebral palsy (CP) and has been inconsistently linked with knee pain. The definitive cause of knee pain is unknown, but may result from increased joint forces due to crouch gait kinematics. Our purpose was to determine whether knee pain is positively associated with knee flexion in gait among a large sample of ambulatory individuals with CP. We hypothesized that knee pain prevalence would increase as knee flexion increased. METHODS: In this retrospective study, pain questionnaire and 3-dimensional gait analysis data from 2015 to 2018 were extracted from the medical records of individuals with CP who had a clinical gait analysis. The pain questionnaire asked caregivers/patients to indicate the location of pain and when it occurs. A multivariate logistic regression was performed with minimum knee flexion in stance, patella alta, age, and sex as predictors of knee pain. RESULTS: Among the 729 participants included in the analysis, 147 reported knee pain (20.1%). The odds of knee pain were not associated with minimum knee flexion in stance or sex. However, the odds of knee pain increased 73.2% when patella alta was present (P=0.008) and tended to increase 2.2% as age increased (P=0.059). CONCLUSIONS: The data suggest that there is not a meaningful association between crouch gait and knee pain. Having patella alta was associated with pain. Further studies that use validated pain questionnaires are needed to understand the multifactorial etiology of knee pain within ambulatory individuals with CP. LEVEL OF EVIDENCE: Level III-case-control study.

Knee pain and crouch gait in individuals with cerebral palsy: what impact does crouch-related surgery have?

AIM: To investigate the effect of crouch-related surgery on knee pain in individuals with cerebral palsy. METHOD: We retrospectively identified individuals with two three-dimensional gait analyses at baseline and follow-up visits. All individuals walked in crouch gait at baseline. Visits were 9 months to 42 months apart. Baseline knee pain, age, crouch-related surgery (yes/no), and minimum knee flexion at follow-up were entered into a logistic regression to predict follow-up knee pain. RESULTS: Thirty-two individuals (21 males, 11 females; mean [SD] age 12y 10mo [2y 5mo]; 8y 1mo-18y 7mo) received crouch-related surgery, while 19 were managed non-surgically. At baseline, knee pain prevalence was 38% in the surgical group and 21% in the non-surgical group. At follow-up, 34% of the surgical group and 16% of the non-surgical group had knee pain (odds ratio: 2.809, p=0.285). INTERPRETATION: Crouch-related surgery does not appear to decrease knee pain prevalence compared to a comparison group, based on this preliminary study. Further investigation of the roles of these procedures is indicated with regards to this patient-reported outcome. What this paper adds Approximately 38% of individuals undergoing crouch-related surgery had knee pain. Approximately 42% of individuals with baseline knee pain who had surgery still had knee pain 1 year postoperatively. Approximately 50% of those with baseline knee pain managed non-surgically still had knee pain 1 year later. Crouch-related surgery tended not to decrease knee pain prevalence 1 year postoperatively.

Dolor de rodilla y marcha en cuclillas en personas con parálisis cerebral: ¿qué impacto tiene la cirugía indicadas para esta deformidad? OBJETIVO: Investigar el efecto de la cirugía relacionada con la marcha en cuclillas con el dolor de rodilla en personas con parálisis cerebral. MÉTODO: Identificamos retrospectivamente a los individuos con dos análisis tridimensionales de la marcha al inicio y en las visitas de seguimiento. Todos los individuos caminaron en cuclillas al inicio del estudio. Las visitas fueron de 9 a 42 meses de diferencia. El dolor al inicio, edad, la cirugía relacionada con este tipo de marcha (sí / no) y la flexión mínima de la rodilla en el seguimiento, se ingresaron en una regresión logística para predecir el dolor de rodilla de seguimiento. RESULTADOS: Treinta y dos individuos (21 varones, 11 mujeres; media [DE] edad 12 años 10 meses [2 años 5 meses]; 8 años 1 mes - 18 años 7 meses) recibieron cirugía para corregir esta alteración, mientras que 19 fueron manejados sin cirugía. Al inicio del estudio, la prevalencia del dolor de rodilla fue del 38% en el grupo quirúrgico y del 21 por ciento en el grupo no quirúrgico. En el seguimiento, el 34% del grupo quirúrgico y el 16% del grupo no quirúrgico tenían dolor de rodilla (odds ratio: 2,809, p = 0,285). INTERPRETACIÓN: Según este estudio preliminar, la cirugía relacionada para la marcha en cuclillas, no parece disminuir la prevalencia del dolor de rodilla en comparación con un grupo de comparación. Se sugiere una investigación adicional de las funciones de estos procedimientos con respecto a los resultados informados por pacientes.

Dor no joelho e marcha agachada em indivíduos com paralisia cerebral: qual o impacto da cirurgia relacionada à marcha agachada? OBJETIVO: Investigar o efeito de cirurgia relacionada à marcha agachada na dor no joelho de indivíduos com paralisia cerebral. MÉTODO: Identificamos retrospectivamente indivíduos com duas análises tridimensionais da marcha em visitas de linha de base e acompanhamento. Todos os indivíduos apresentavam marcha agachada na linha de base. As visitas tiveram de 9 a 42 meses de distância. A dor no joelho, idade, cirurgia relacionada à marcha agachada (sim/não) na linha de base, e flexão mínima do joelho no acompanhamento foram inseridas em uma regressão logístia para predizer a dor no joelho no acompanhamento. RESULTADOS: Trinta e dois indivíduos (21 do sexo masculino, 11 do sexo feminino; média [DP] de idade 12a 10m [2a 5m]; 8a 1m-18a 7m) receberam cirurgia relacionada à marcha agachada, enquanto 19 tiveram manejo não-cirúrgico. Na linha de base, a prevalência de dor no joelho era 38 por cento no grupo cirúrgico, e 21 por cento no grupo não-cirúrgico. No acompanhamento, 34 por cento do grupo cirúrgico e 16 por cento do grupo não cirúrgico tiveram dor no joelho (taxa de risco: 2,809, p=0,285). INTERPRETAÇÃO: A cirurgia relacionada à marcha agachada não parece diminuir a prevalência de dor no joelho em relação a um grupo de comparação, com base neste estudo preliminar. Mais investigações sobre o papel destes procedimentos são indicadas, com relação a este desfecho relatado pelos pacientes.

Association of back pain and pelvic tilt during gait in individuals with cerebral palsy.

BACKGROUND: Back pain prevalence may increase with lumbar lordosis during standing in individuals with cerebral palsy (CP). Multiple interventions undertaken in individuals with CP have been shown to increase anterior pelvic tilt. RESEARCH QUESTION: Are pelvic tilt and trunk tilt (proxy measurements for lumbar lordosis) during gait associated with back pain prevalence in ambulatory individuals with CP? METHODS: A retrospective investigation was performed among all patients with cerebral palsy visiting a single clinical motion analysis laboratory over a 3.5 year period (January 2015 - May 2018) who also had complete pain questionnaire data. Back pain prevalence and its association with sagittal plane kinematic parameters (pelvic tilt and trunk tilt) were analyzed. RESULTS: Among the 700 patients that met the inclusion criteria, 594 were children and 106 were adults. Back pain prevalence was 11.1% in children and 36.8% in adults. As pelvic tilt and age increased, back pain increased (odds ratio 95% confidence interval: 1.002-1.061 and 1.052-1.109, respectively). Walking with an assistive device was not associated with back pain, nor was trunk tilt. SIGNIFICANCE: Back pain was more common with increasing age in ambulatory individuals with CP. After controlling for assistive device use and age, there was a weak relationship between pelvic tilt and back pain. Future studies are needed to determine if this is this a causal relationship.

How Hydrologic Connectivity Regulates Water Quality in River Corridors.

Downstream flow in rivers is repeatedly delayed by hydrologic exchange with off-channel storage zones where biogeochemical processing occurs. We present a dimensionless metric that quantifies river connectivity as the balance between downstream flow and the exchange of water with the bed, banks, and floodplains. The degree of connectivity directly influences downstream water quality - too little connectivity limits the amount of river water exchanged and leads to biogeochemically inactive water storage, while too much connectivity limits the contact time with sediments for reactions to proceed. Using a metric of reaction significance based on river connectivity, we provide evidence that intermediate levels of connectivity, rather than the highest or lowest levels, are the most efficient in removing nitrogen from Northeastern United States' rivers. Intermediate connectivity balances the frequency, residence time, and contact volume with reactive sediments, which can maximize the reactive processing of dissolved contaminants and the protection of downstream water quality. Our simulations suggest denitrification dominantly occurs in riverbed hyporheic zones of streams and small rivers, whereas vertical turbulent mixing in contact with sediments dominates in mid-size to large rivers. The metrics of connectivity and reaction significance presented here can facilitate scientifically based prioritizations of river management strategies to protect the values and functions of river corridors.

Pregnancy Results in Lasting Changes in Knee Joint Laxity.

BACKGROUND: Altered joint laxity can contribute to joint dysfunction. Knee joint laxity has been shown to increase during pregnancy, but its long-term persistence is unknown. OBJECTIVE: To determine whether pregnancy leads to lasting increases in knee joint compliance and laxity that persist longer than 4 months postpartum. DESIGN: Prospective cohort study. SETTING: A motion analysis laboratory at an academic medical center. PARTICIPANTS: Fifty healthy women in their first trimester of pregnancy (mean ± SD 29.2 ± 4.3 years old and baseline body mass index 26.0 ± 5.4 kg/m2 ) were recruited. INTERVENTION: End-range knee laxity and midrange joint compliance were measured during the first trimester and 19 ± 4 weeks postpartum. Anterior-posterior and varus-valgus laxity were measured using 3-dimensional motion tracking while applying forces and moments in each respective plane using the Vermont Knee Laxity Device. Nonlinear models were constructed to assess relations between applied forces and joint translation, comparing early pregnancy with postpartum. OUTCOMES: Multiplanar knee laxity and compliance. RESULTS: Peak varus-valgus (20-22%; P = .001) and posterior translation (51%; P < .001) of the tibia relative to the femur decreased from baseline, with a concomitant decrease in laxity (P < .001) and compliance (P = .039) in the coronal plane and in the posterior direction in primiparous (P = .009) and multiparous (P = .014) women. For primiparous women, laxity (P < .001) and compliance (P = .009) increased in the anterior direction. CONCLUSIONS: Pregnancy resulted in a lasting decrease in multiplanar knee laxity and compliance in the varus and posterior directions with an increase in anterior compliance. The effects of these changes in laxity and compliance of the passive stabilizers on knee loading patterns, articular contact stresses, and risk for osteoarthritis and other musculoskeletal disorders will require additional research. LEVEL OF EVIDENCE: II.

Thresholds of lake and reservoir connectivity in river networks control nitrogen removal.

Lakes, reservoirs, and other ponded waters are ubiquitous features of the aquatic landscape, yet their cumulative role in nitrogen removal in large river basins is often unclear. Here we use predictive modeling, together with comprehensive river water quality, land use, and hydrography datasets, to examine and explain the influences of more than 18,000 ponded waters on nitrogen removal through river networks of the Northeastern United States. Thresholds in pond density where ponded waters become important features to regional nitrogen removal are identified and shown to vary according to a ponded waters' relative size, network position, and degree of connectivity to the river network, which suggests worldwide importance of these new metrics. Consideration of the interacting physical and biological factors, along with thresholds in connectivity, reveal where, why, and how much ponded waters function differently than streams in removing nitrogen, what regional water quality outcomes may result, and in what capacity management strategies could most effectively achieve desired nitrogen loading reduction.

Gait pathology subtypes are not associated with self-reported fall frequency in children with cerebral palsy.

BACKGROUND: Trips and falls are common concerns reported by parents of children with cerebral palsy. Specific gait pathologies (excessive internal hip rotation, intoeing, and stiff knee gait) are anecdotally associated with higher rates of falls. RESEARCH QUESTION: Is fall frequency higher for the aforementioned gait pathologies? METHODS: Parent-reported fall frequency from 1063 children with cerebral palsy who also had a three-dimensional gait analysis was retrospectively reviewed. Frequency of 10 common gait pathologies was determined and fall frequency for the gait pathologies of interest were compared to matched control groups. Possible effects of Gross Motor Functional Classification System (GMFCS) level and age on fall frequency were also assessed and matched in the control group, as appropriate. RESULTS: In general, parent-reported fall frequency increased from GMFCS level I to II and then decreased until level IV. Moreover, younger children tended to report greater fall frequency, though children who reported never falling were of similar age as those who reported weekly falls, resulting in an inverted-U shaped relationship. Children with cerebral palsy who walked with excessive internal hip rotation, excessive intoeing, or stiff knee gait did not report increased fall frequencies compared to other children with cerebral palsy matched on GMFCS level and age that did not walk with those gait patterns. Approximately 35% of children reported never falling, 35% reported falling daily, and 30% reported falling monthly or weekly for each gait pattern. Therefore, elevated fall frequency appears to be a generic problem for most children with CP rather than a function of a specific gait pattern. SIGNIFICANCE: Clinicians should be aware of these relationships, or lack thereof, when trying to decipher the cause of a child's falling and when determining appropriate interventions. Future studies may seek to more objectively quantify fall frequency, as self-report is the main limitation of this study.

Proximal versus distal femoral derotation osteotomy in bilateral cerebral palsy.

AIM: Femoral derotation osteotomy (FDO) can be conducted either proximally or distally to correct internal rotation gait (IRG) and increased anteversion in children with cerebral palsy (CP). Previous studies with limited numbers of participants have presented comparable short-term static and kinematic outcomes for both techniques. The objective of this retrospective multicentre study was to verify this thesis with a larger number of patients. METHOD: In total, 119 children with CP and IRG were included after matching the groups on preoperative mean stance hip rotation: 67 intertrochanteric (proximal group) FDO (average age at surgery 9y [SD 3y]); 52 supracondylar (distal group) FDO (average age at surgery 12y [SD 3y]). One random limb of each child was analyzed. Both transverse plane kinematic gait data and torsional parameters of clinical examination were assessed preoperatively and postoperatively. RESULTS: On average, both groups' mean hip rotation and midpoint of hip rotation improved postoperatively, and groups did not differ preoperatively or postoperatively for these variables (p>0.05). INTERPRETATION: The osteotomy location does not influence short-term gait kinematics nor static measurements. Therefore, the choice of performing proximal or distal FDO in children with CP for treatment of IRG and increased anteversion should be motivated by considerations other than these outcome parameters. WHAT THIS PAPER ADDS: Femoral derotation osteotomy (FDO) location does not influence mean stance hip rotation in cerebral palsy (CP). FDO location does not influence mid-point hip rotation in CP. FDO location should be motivated by concomitant procedures performed.

Long-Term Outcomes of Distal Femoral Extension Osteotomy and Patellar Tendon Advancement in Individuals with Cerebral Palsy.

BACKGROUND: We examined long-term outcomes across the domains of the International Classification of Functioning, Disability and Health for 2 groups of participants with cerebral palsy who demonstrated crouch gait at clinical gait analysis. One group underwent a distal femoral extension osteotomy with patellar tendon advancement (DFEO + PTA). The other group received other treatments (non-DFEO + PTA). METHODS: Fifty-one participants returned for a long-term gait analysis, physical examination, energy consumption test, knee radiographs, and questionnaires (median, 13 years post-DFEO + PTA or post-baseline [range, 8 to 21 years]). A subset of participants in the DFEO + PTA group also had a short-term analysis (9 to 24 months postoperatively). RESULTS: Participants were reasonably well-matched at baseline, although the DFEO + PTA group demonstrated greater crouch: minimum knee flexion, a median of 37° (width of the interquartile range, 12°) compared with 27° (9°); and knee flexion contracture, a median of 15° (10°) compared with 10° (5°). The gait deviation index (GDI) and sagittal plane knee kinematics were most improved at short term for the DFEO + PTA participants, with a subsequent slight decline at long-term analysis. Fewer DFEO + PTA participants were in crouch at long term (37% compared with 65%). At the long-term assessment, group scores for function, mobility, participation, quality of life, and most pain questionnaires were similar. Knee pain and osteoarthritis ratings did not differ between the groups. CONCLUSIONS: At long-term analysis, DFEO + PTA improves stance phase knee extension and knee flexion contracture compared with conventional treatment, but these benefits do not translate to improved activity, participation, or knee pain in early adulthood. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.