Fit-for-Purpose Ki-67 Immunohistochemistry Assays for Breast Cancer.

New therapies are being developed for breast cancer, and in this process, some "old" biomarkers are reutilized and given a new purpose. It is not always recognized that by changing a biomarker's intended use, a new biomarker assay is created. The Ki-67 biomarker is typically assessed by immunohistochemistry (IHC) to provide a proliferative index in breast cancer. Canadian laboratories assessed the analytical performance and diagnostic accuracy of their Ki-67 IHC laboratory-developed tests (LDTs) of relevance for the LDTs' clinical utility. Canadian clinical IHC laboratories enrolled in the Canadian Biomarker Quality Assurance Pilot Run for Ki-67 in breast cancer by invitation. The Dako Ki-67 IHC pharmDx assay was employed as a study reference assay. The Dako central laboratory was the reference laboratory. Participants received unstained slides of breast cancer tissue microarrays with 32 cases and performed their in-house Ki-67 assays. The results were assessed using QuPath, an open-source software application for bioimage analysis. Positive percent agreement (PPA, sensitivity) and negative percent agreement (NPA, specificity) were calculated against the Dako Ki-67 IHC pharmDx assay for 5%, 10%, 20%, and 30% cutoffs. Overall, PPA and NPA varied depending on the selected cutoff; participants were more successful with 5% and 10%, than with 20% and 30% cutoffs. Only 4 of 16 laboratories had robust IHC protocols with acceptable PPA for all cutoffs. The lowest PPA for the 5% cutoff was 85%, for 10% was 63%, for 20% was 14%, and for 30% was 13%. The lowest NPA for the 5% cutoff was 50%, for 10% was 33%, for 20% was 50%, and for 30% was 57%. Despite many years of international efforts to standardize IHC testing for Ki-67 in breast cancer, our results indicate that Canadian clinical LDTs have a wide analytical sensitivity range and poor agreement for 20% and 30% cutoffs. The poor agreement was not due to the readout but rather due to IHC protocol conditions. International Ki-67 in Breast Cancer Working Group (IKWG) recommendations related to Ki-67 IHC standardization cannot take full effect without reliable fit-for-purpose reference materials that are required for the initial assay calibration, assay performance monitoring, and proficiency testing.

Radioactive Seed Localization Versus Wire-Guided Localization for Nonpalpable Breast Cancer: A Cost and Operating Room Efficiency Analysis.

BACKGROUND: This study aimed to compare the cost and resource use between our first-year experience using breast-conserving surgery (BCS) with radioactive seed localization (RSL) and the previous-year standard practice of BCS with wire-guided localization (WGL) for patients with nonpalpable breast cancer at a large Canadian tertiary center. METHODS: For this retrospective cohort study, data for BCS cases with RSL was collected from 1 April 2015 to 31 March 2016 and for BCS cases with WGL from 1 April 2014 to 31 March 2015. RESULTS: The study compared 153 WGL patients with 194 RSL patients. The two groups had no significant demographic differences. The average cost per patient for RSL, including opportunity costs, was $250.90 versus $1130.41 for WGL. Dedicated allocated radiology appointments to RSL increased (9 per day), and fewer radiologists were required for these procedures per day. Patients were transported to the operating room more quickly for RSL procedures (120 vs. 254 min; p < 0.001). Fewer vasovagal reactions occurred after insertion of RSL versus WGL (p = 0.05). No significant differences were observed in terms of surgical time, specimen volume, positive margins, or margin reexcision rates. No significant differences in postoperative complication rates were observed. CONCLUSIONS: In this study, RSL had lower costs than WGL, allowed for more efficient use of radiology scheduling and resources, and had shorter wait times for patients on their day of surgery. In addition, RSL led to fewer vasovagal reactions at insertion. Therefore, RSL should be used instead of WGL given the reduced cost, decreased need of human resources, improved efficiency, and potential benefits to the patient experience.

Benign Papillomas of the Breast Diagnosed on Large-Gauge Vacuum Biopsy compared with 14 Gauge Core Needle Biopsy - Do they require surgical excision?

To evaluate whether biopsy with vacuum-assisted biopsy (VAB) devices improves histologic underestimation rates of benign papillomas when compared to smaller bore core needle biopsy (CNB) devices. Patients with biopsy-proven benign papillomas with surgical resection or minimum 12 months follow-up were selected. Two breast pathologists reviewed all pathology slides of percutaneous and excisional biopsy specimens. Histologic underestimation rates for lesions biopsied with 10-12 Gauge (G) VAB were compared to those with 14G CNB. A total of 107 benign papillomas in 107 patients from two centers were included. There were 60 patients (mean age 57 years, SD 10.3 years) diagnosed with VAB and 47 patients (mean age 57.6 years, SD 11.3 years) with 14G CNB who underwent surgical excision or imaging follow-up. The upgrade rate to ductal carcinoma in situ or invasive carcinoma was 1.6% (1/60) with VAB and 8.5% (4/47) with 14G. Upgrade to atypia was 3.3% (2/60) after VAB and 10.6% (5/47) with CNB. The total underestimation rates were 5% (3/60) with VAB and 19.1% (9/47) with CNB. The odds of an upgrade to malignancy was 5.5 times higher with a 14G needle than VAB (95% CI: 0.592-50.853, p = 0.17). We observed a lower but not statistically significant upgrade rate to malignancy and atypia with the use of the 10-12 G VAB as compared with 14G CNB. When a papilloma without atypia is diagnosed with vacuum biopsy there is a high likelihood that it is benign; however, if surgical excision is not performed, long-term follow-up is still required.

Viability assessment of the chondral flap in patients with cam-type femoroacetabular impingement: a preliminary report.

BACKGROUND: Delaminated acetabular cartilage is a common finding in patients undergoing surgical dislocation or hip arthroscopy in the treatment of cam-type femoroacetabular impingement. Current treatment involves resection of the free cartilage flap with or without acetabular rim trimming. The viability of the delaminated cartilage flap is not known. We sought to examine if the acetabular cartilage still has viable cartilage cells and, if so, what type of cartilage is present. METHODS: We examined the delaminated cartilage flaps from patients undergoing surgical dislocation and osteochondroplasty for symptomatic cam-type impingement. We performed hematoxylin and eosin staining and histological analysis using light microscopy to determine cartilage viability and cartilage type. RESULTS: We examined 12 delaminated cartilage flaps from 11 patients (10 men, 1 woman, average age 30.1 yr). Ninety percent chondrocyte viability was confirmed in 11 of 12 flaps. Six of 12 flaps were composed predominantly of hyaline cartilage, 4 were a mixed population of fibrocartilage and hyaline cartilage and 2 were predominantly fibrocartilage. CONCLUSION: Our findings suggest that the delaminated cartilage flap in patients with femoroacetabular impingement may retain a large amount of viable chondrocytes. Development of surgical techniques focusing on refixation of this flap as an alternative to excision and microfracture should be considered.

CONTEXTE: La présence d'un cartilage acétabulaire délaminé s'observe souvent chez les patients qui subissent une dislocation chirurgicale ou une arthroscopie de la hanche pour le traitement du conflit fémoro-acétabulaire de type came. Le traitement actuel repose sur la résection du lambeau articulaire libre, avec ou sans résection du rebord acétabulaire. La viabilité du lambeau de cartilage délaminé est inconnue. Nous avons voulu vérifier si le cartilage acétabulaire conserve des cellules de cartilage viables et le cas échéant, quel type de cartilage est présent. MÉTHODES: Nous avons examiné les lambeaux de cartilage délaminés provenant de patients soumis à une dislocation et ostéochondroplastie chirurgicales pour un conflit de type came symptomatique. Nous avons procédé à une coloration à l'hématoxyiline et à l'éosine, ainsi qu'à une analyse histologique par microscopie optique pour déterminer le type de cartilage et sa viabilité. RÉSULTATS: Nous avons examiné 12 lambeaux de cartilage délaminé provenant de 11 patients (10 hommes, 1 femme, âgés en moyenne de 30,1 ans). La viabilité des chondrocytes a été confirmée à 90 % pour 11 lambeaux sur 12. Six lambeaux sur 12 se composaient surtout de cartilage hyalin, 4 étaient un mélange de fibrocartilage et de cartilage hyalin et 2 étaient principalement du fibrocartilage. CONCLUSION: Selon nos observations, le lambeau de cartilage délaminé chez les patients qui présentent un conflit fémoro-acétabulaire peut conserver une forte proportion de chondrocytes viables. Il faut envisager la mise au point de techniques chirurgicales axées sur la « refixation ¼ de ce lambeau comme solution de rechange à l'exérèse et à la microfracture.

Perception of weight-bearing and effort distribution during sit-to-stand in individuals post-stroke.

The objectives were to assess whether individuals who are poststroke can rate their perceived knee effort distribution during sit-to-stand tasks in various foot positions, to quantify their errors of perception and to compare these to their errors in weight-bearing perception. Weight-bearing distribution was assessed in hemiparetic participants (N = 19) using a force platform. Electromyographic (EMG) data normalized to maximal EMG values were used to quantify knee effort distribution. The difference between participants' real weight bearing and knee effort and the perceived values rated on a visual analog scale defined their errors of weight-bearing and effort perception. The perception of effort and weight bearing, and the errors therein, were compared among the four foot positions. Participants perceived only the changes induced by the different foot positions on their weightbearing distribution, not on their knee effort distribution, and they made greater perception errors with the knee effort distribution than with the weight-bearing distribution.

Neoadjuvant Chemotherapy in Breast Cancer: Review of the Evidence and Conditions That Facilitated Its Use during the Global Pandemic.

Practice and behaviour change in healthcare is complex, and requires a set of critical steps that would be needed to implement and sustain the change. Neoadjuvant chemotherapy for breast cancer is traditionally used for locally advanced disease and is primarily advantageous for surgical downstaging purposes. However, it does also offer patients with certain biologic subtypes such as the triple negative or Her2 positive breast cancers the opportunity to improve survival, even in early stage disease. During the height of the pandemic, an opportunity and motivation for the increased use of neoadjuvant therapy in breast cancer was identified. This paper describes the conditions that have supported this practice change at the provider and institutional levels. We also include our own institutional algorithm based on tumor biology and extent of disease that have guided our decisions on breast cancer management during the pandemic. Our processes can be adapted by other institutions and breast oncology practices in accordance with local conditions and resources, during and beyond the pandemic.

Perception of weight-bearing distribution during sit-to-stand tasks in hemiparetic and healthy individuals.

BACKGROUND AND PURPOSE: It is unknown whether hemiparetic individuals are aware of their weight-bearing asymmetry during sit-to-stand tasks. This study compared the error between hemiparetic and healthy individuals' perception of weight-bearing and their actual weight-bearing distribution during the sit-to-stand task and analyzed the association between the knee extensor muscle strength and the weight-bearing distribution and perception. METHODS: Nineteen unilateral hemiparetic subjects and 15 healthy individuals participated in the study. They performed the sit-to-stand transfer on force platforms under different foot placements (spontaneous and symmetrical) and had to rate their perceived weight-bearing distribution at the lower limbs on a visual analog scale. The strength of the knee extensors was assessed with a Biodex dynamometer. RESULTS: The hemiparetic individuals presented greater weight-bearing asymmetry and errors of perception than the healthy individuals. Although no significant association was found between strength and weight-bearing perception, moderate associations were found between strength and weight-bearing distribution for both the spontaneous (r=0.75, P<0.01) and symmetrical (r=0.71, P<0.01) foot position conditions. CONCLUSIONS: This study revealed that individuals with hemiparesis after a stroke do not perceive themselves as asymmetrical when executing the sit-to-stand transfer and that the knee extensor strength is a factor linked to their weight-bearing asymmetry, not to their perception.

Predictors of success for physiotherapy treatment in women with persistent postpartum stress urinary incontinence.

OBJECTIVE: To identify predictors of success for physiotherapy treatment in women with persistent postpartum stress urinary incontinence (SUI). DESIGN: Secondary analysis of data from a single-blind randomized controlled trial comparing 2 physiotherapy intervention programs for persistent SUI in postpartum women. SETTING: Obstetric clinic of a mother and children's university hospital. PARTICIPANTS: Women, ages 23 to 39 (N=57), were randomized to 1 of 2 pelvic floor muscle (PFM) training programs, 1 with and 1 without abdominal muscle training. INTERVENTION: Over 8 weeks, participants in each group followed a specific home exercise program once a day, 5 days a week. In addition, participants attended individual weekly physiotherapy sessions throughout the 8-week program. MAIN OUTCOME MEASURES: Treatment success was defined as a pad weight gain of less than 2 g on a 20-minute pad test with standardized bladder volume after 8 weeks' treatment. The relationship between potential predictive PFM function variables as measured by a PFM dynamometer and success of physiotherapy was studied using forward stepwise multivariate logistic regression analyses. RESULTS: Forty-two women (74%) were classified as treatment successes, and 15 (26%) were not. Treatment success was associated with lower pretreatment PFM passive force and greater PFM endurance pretreatment, but the latter association was barely statistically significant. This model explained between 23% (Cox and Snell R(2)) and 34% (Nagelkerke R(2)) of the outcome variability. CONCLUSIONS: The results contribute new information on predictors of success for physiotherapy treatment in women with persistent postpartum SUI.

Selecting Patients for Oncotype DX Testing Using Standard Clinicopathologic Information.

INTRODUCTION: Indiscriminate ordering of Oncotype DX (ODX) is expensive and of poor value to patients, physicians, and health care providers. The 3 Magee equations, Gage Algorithm, and University of Tennessee predictive algorithm all use standard clinicopathologic data to provide surrogate ODX scores. In this hypothesis-generating study, we evaluated whether these prognostic scores could be used to identify patients unlikely to benefit from additional ODX testing. PATIENTS AND METHODS: Retrospective data was collected from 302 patients with invasive ductal breast cancer and available ODX scores. Additional data was available for: Magee equations 1 (212 patients), 2 (299 patients), 3 (212 patients), Gage Algorithm (299 patients), and University of Tennessee predictive algorithm (286 patients). ODX scores were banded according to the TAILORx results. RESULTS: Correlation with ODX scores was between 0.7 and 0.8 (Gage), 0.8 and 0.9 (Magee 2, University of Tennessee predictive algorithm), and > 0.9 (Magee 1 and 3). Magee 3 was the most robust and is proposed as a screening tool: for patients aged ≤ 50 years, ODX testing would be not required if the Magee 3 score was < 14 or ≥ 20; for those aged > 50 years, ODX would not be required if the Magee 3 score was < 18 or ≥ 26. Using these cut-offs, 110 (51.9%) of 212 patients would be deemed as not requiring ODX testing, and 109 (99.1%) of110 patients would be appropriately managed. CONCLUSIONS: Use of all formulae, and the Magee 3 equation in particular, are proposed as possible screening tools for ODX testing, resulting in significantly reduced frequency of ODX testing. This requires validation in other populations.

Complex rearrangement of chromosomes 19, 21, and 22 in Ewing sarcoma involving a novel reciprocal inversion-insertion mechanism of EWS-ERG fusion gene formation: a case analysis and literature review.

EWS-ERG Ewing sarcoma (ES) gene fusions often result from complex chromosomal rearrangements. We report an unusually aggressive case of ES with an EWS-ERG fusion gene that appeared to be a result of a simple balanced and reciprocal translocation, t(19;22)(q13.2;q12.2). Subsequent molecular investigation of the primary tumor, the metastasis, and a cell line generated from this ES permitted reconstruction of each genomic step in the evolution of this complex EWS-ERG fusion. We elucidated a new mechanism of reciprocal insertion inversion between chromosome 21 and 22, involving cryptic alterations to both the ERG and EWS genes. Molecular cytogenetic investigation, using systematic analysis with locus-specific probes, identified the cognate genomic breakpoints within chromosome 21 and 22, mandatory for the excision and exchange of both 3'ERG and 3'EWS, resulting in the formation of the EWS-ERG fusion gene present on the der(22). Array comparative genomic hybridization and fluorescence in situ hybridization studies of the ES cell line derived from this tumor identified additional acquired chromosomal and genomic abnormalities, likely associated with establishment and adaptation to in vitro growth. Notably, the cell line had lost one copy of the RB1 gene within the 13q13.1 approximately q14.2 region, and also had a near-tetraploid karyotype. The significance of these findings and their relationship to other reports of variant and complex ES translocations involving the ERG gene are reviewed.

Reliability of dynamometric passive properties of the pelvic floor muscles in postmenopausal women with stress urinary incontinence.

UNLABELLED: The passive properties of the pelvic floor muscles (PFM) might play a role in stress urinary incontinence (SUI) pathophysiology. AIM: To investigate the test-retest reliability of the dynamometric passive properties of the PFM in postmenopausal SUI women. METHODS: Thirty-two SUI postmenopausal women were convened to two sessions 2 weeks apart. In each session, the measurements were repeated twice. The pelvic floor musculature was evaluated in four different conditions: (1) forces recorded at minimal aperture (initial passive resistance); (2) passive resistance at maximal aperture; (3) five lengthening and shortening cycles (Forces and passive elastic stiffness (PES) were evaluated at different vaginal apertures. Hysteresis was also calculated.); (4) Percentage of passive resistance loss after 1 min of sustained stretching was computed. The generalizability theory was used to calculate two reliability estimates, the dependability indices (Phi) and the standard error of measurement (SEM), for one session involving one measurement or the mean of two measurements. RESULTS: Overall, the reliability of the passive properties was good with indices of dependability of 0.75-0.93. The SEMs for forces and PES were 0.24-0.67 N and 0.03-0.10 N/mm, respectively, for mean, maximal and 20-mm apertures, representing an error between 13% and 23%. Passive forces at minimal aperture showed lower reliability (Phi = 0.51-0.57) compared with other vaginal openings. The aperture at a common force of 0.5 N was the only parameter demonstrating a poor reliability (Phi = 0.35). CONCLUSION: This new approach for assessing PFM passive properties showed enough reliability for highly recommending its inclusion in the PFM assessment of SUI postmenopausal women.

The assessment of back muscle capacity using intermittent static contractions. Part II: validity and reliability of biomechanical correlates of muscle fatigue.

INTRODUCTION: In a previous paper, standard surface electromyographic (EMG) indices of muscle fatigue, which are based on the lowering of the median or mean frequencies of the EMG power spectrum in time, were applied during an intermittent absolute endurance test and were evaluated relative to criterion validity and test-retest reliability. The aims of this study were to assess mechanical and alternative EMG correlates of muscle fatigue. METHODS: Healthy subjects (44 males and 29 females; age: 20-55 yrs) performed three maximal voluntary contractions (MVC) and an endurance test while standing in a static dynamometer. Surface EMG signals were collected from four pairs of back muscles (multifidus at the L5 level, iliocostalis lumborum at L3, and longissimus at L1 and T10). The test, assessing absolute endurance (90 Nm torque), consisted of performing an intermittent extension task to exhaustion. Strength was defined as the peak MVC whereas our endurance criterion was defined as the time to reach exhaustion (Tend) during the endurance test. Mechanical indices quantifying physiological tremor and steadiness were computed from the dynamometer signals (L5/S1 extension moments) along with EMG indices presumably sensitive to variable load sharing between back muscle synergists during the endurance test. RESULTS: Mechanical indices were significantly correlated to Tend (r range: -0.47 to -0.53) but showed deceiving reliability results. Conversely, the EMG indices were correlated to Tend (r range: -0.43 to -0.63) with some of them particularly correlated to Strength (r=-0.72 to -0.81). In addition, their reliability results were acceptable (intra-class correlation coefficient >0.75; standard error of measurement <10% of the mean) in many cases. Finally, several analyses substantiated their physiological relevance. These findings imply that these new EMG indices could be used to predict absolute endurance as well as strength with the use of a single intermittent and time-limited (5-10min) absolute endurance test, a practical way to assess the back capacity of chronic low back pain subjects.

The assessment of back muscle capacity using intermittent static contractions. Part I - Validity and reliability of electromyographic indices of fatigue.

INTRODUCTION: Back muscle capacity is impaired in chronic low back pain patients but no motivation-free test exists to measure it. The aims of this study were to assess the reliability and criterion validity of electromyographic indices of muscle fatigue during an intermittent absolute endurance test. METHODS: Healthy subjects (44 males and 29 females; age: 20-55 yrs) performed three maximal voluntary contractions (MVC) and a fatigue test while standing in a static dynamometer. Surface EMG signals were collected from four pairs of back muscles (multifidus at the L5 level, iliocostalis lumborum at L3, and longissimus at L1 and T10). The fatigue test, assessing absolute endurance (90-Nm torque), consisted in performing an intermittent extension task to exhaustion. Strength was defined as the peak MVC whereas our endurance criterion was defined as the time to reach exhaustion (Tend) during the fatigue test. From the first five min (females) or ten min (males) of EMG data, frequency and time-frequency domain analyses were applied to compute various spectral indices of muscle fatigue. RESULTS: The EMG indices were more reliable when computed from the time-frequency domain than when computed from the frequency domain, but showed comparable correlation results (criterion validity) with Tend and Strength. Some EMG indices reached moderate to good correlation (range: 0.64-0.69) with Tend, lower correlations (range: 0.39-0.55) with Strength, and good to excellent between-day test-retest reliability results (intra-class correlation range: 0.75-0.83). The quantification of the spectral content more locally in different frequency bands of the power spectrum was less valid and reliable than the indices computed from the entire power spectrum. Differences observed among muscles were interpreted in light of specific neuromuscular activation levels that were observed during the endurance test. These findings supported the use of an intermittent and time-limited (5-10min) absolute endurance test, that is a practical way to assess the back capacity of chronic low back pain subjects, to assess absolute endurance as well as strength with the use of electromyographic indices of muscle fatigue.

Interactions between foot placement, trunk frontal position, weight-bearing and knee moment asymmetry at seat-off during rising from a chair in healthy controls and persons with hemiparesis.

OBJECTIVE: To assess the interaction of foot placement, trunk frontal position, weight-bearing and knee moment asymmetry at seat-off when rising from a chair. DESIGN: Cross-sectional study. SUBJECTS: Seventeen subjects with hemiparesis and 15 healthy controls. METHODS: Trunk position, weight-bearing and knee moment asymmetry were quantified by kinetic and kinematic analysis when the subjects rose from a chair using 3 different foot placements: spontaneous, symmetrical and asymmetrical. Asymmetry was defined by the ratio between sides. RESULTS: In the healthy controls, the spontaneous and symmetrical foot placements were associated with an almost vertical trunk position and a symmetrical weight-bearing and knee moment. The asymmetrical foot placement resulted in a trunk displacement towards the foot placed behind, with more weight-bearing and higher moment on this side. The opposite was observed in the hemiparetic participants where the spontaneous and symmetrical foot conditions determined a trunk position and an asymmetry bias towards the unaffected side. Placing the affected foot behind the other reduced the asymmetrical behaviour. CONCLUSION: Changes in weight-bearing are partly associated with the frontal trunk position, and foot placement manipulations can be used to modify weight-bearing distribution. Inference on weight-bearing is possible by observing the trunk position during the sit-to-stand task in persons with hemiparesis.

Quantification of reaction forces during sitting pivot transfers performed by individuals with spinal cord injury.

OBJECTIVES: To quantify the reaction forces exerted under the hands, feet and buttocks when individuals with spinal cord injury performed sitting pivot transfers. DESIGN: Twelve men with paraplegia completed 3 transfers between seats of the same height (0.5 m high) and 3 transfers to a high target seat (0.6 m high). RESULTS: Greater mean and peak vertical reaction forces were always recorded under the hands compared with the feet (p<0.001) during the transfers. Mean vertical reaction forces were similar between the leading and trailing hands (p>0.088) for the 2 transfers studied. However, the mean vertical reaction force underneath the leading hand was greater when transferring between a seat of the same height compared with one of a higher height (p=0.021) and vice-versa for the trailing hand (p=0.0001). The peak vertical reaction force always occurred earlier (p<0.0001) and was greater underneath the trailing hand compared with the leading one (p<0.02), and reached its highest value when transferring to the high target seat (p=0.003). Peak and mean horizontal reaction forces were always higher underneath the trailing hand compared with the leading hand (p<0.001). CONCLUSION: These results provide evidence-based data to better understand transfers and strengthen clinical practice guidelines targeting the preservation of upper extremity integrity.

Effect of increases in plantarflexor and hip flexor muscle strength on the levels of effort during gait in individuals with hemiparesis.

BACKGROUND: Following a stroke, strength gain of the trained affected lower-limb muscles has been observed to result in a change in gait speed, but its effect on other variables related to gait performance has scarcely been studied. The aim of this study was to assess the effect of strength gain of the affected plantarflexors and hip flexors on bilateral levels of effort during gait, in the sagittal plane of movement. METHODS: The levels of effort of 24 chronic hemiparetic participants (mean (standard deviation (SD)): 57.3 (SD 15.5) years), who had strength gains in the ankle and hip muscles following a strengthening programme, were estimated with the muscular utilization ratio during self-selected and maximal speeds. The ratio relates the net moment in gait relative to the muscle's maximal capability. The peak value and the area under the curve of the ratio were used as main outcome measures. FINDINGS: Regardless of speed, strength gains have been noted to cause a significant 12-17% decrease in the peak value of the ratio of the affected plantarflexors and hip flexors with a reduction of the area under the curve of the affected hip flexors' ratio and a trend toward a decrease for the affected plantarflexors at maximal speed. A significant, albeit small increase in self-selected and maximal gait speeds (P<0.05) was also observed post-training. Regardless of assessment time, the peak value of the affected plantarflexors' ratio was greater than that of the affected hip flexors at self-selected speed (P=0.006) and the area under the curve of the affected hip flexors' ratio was greater than that of the affected plantarflexors (P=0.007) at maximal speed. Generally, negative associations (-0.32-0.83) were noted between the changes in the peak value of the ratio and strength but not between the changes in gait speed. INTERPRETATION: The decrease in the peak value of the ratio could be explained by the increase in strength. Becoming stronger, hemiparetic participants favoured a reduction of their levels of effort during walking instead of substantially increasing their gait speed.

Trunk and upper extremity kinematics during sitting pivot transfers performed by individuals with spinal cord injury.

BACKGROUND: Although reaching an optimal level of independence during sitting pivot transfer is crucial for individuals with spinal cord injury, little is known regarding the kinematic requirements of this functional task. METHODS: Ten males with spinal cord injury performed independent sitting pivot transfers between an initial seat and a target one placed at same (50 cm), lower (40 cm), and higher heights (60 cm) than the initial one, using their usual movement strategies. Three-dimensional trunk, shoulder, elbow and wrist kinematics were collected bilaterally during sitting pivot transfers. Each sitting pivot transfer was divided into three phases for analysis: pre-lift, lift-pivot and post-lift. Temporal parameters were also documented. FINDINGS: Peak shoulder extension displacement and velocities were always higher at the leading shoulder compared to the trailing one (P<0.004), and almost coincided with peak trunk velocities early during the lift phase. With increasing target seat height, shoulder flexion (P<0.011) and elbow extension (P<0.013) displacements and velocities of the trailing upper extremity augmented and reached higher values at this upper extremity compared to the leading upper extremity, with one exception at the shoulder. Elbows generally remained flexed (min=28-56 degrees ) during the lift phase of all transfers whereas extreme wrist extension positions (max=84-88 degrees ) were documented across all transfers. Total durations of transfers (2.6-2.8s) and lift-pivot phases (1.0-1.3s) were not affected by target seat heights. INTERPRETATION: Sitting pivot transfers are characterized by substantial angular displacements and velocities at the trunk and upper extremities. Some kinematic parameters documented during sitting pivot transfers may increase the risk of developing secondary musculoskeletal impairments in this population.

Effects of cadence on energy generation and absorption at lower extremity joints during gait.

BACKGROUND: Information regarding kinetic changes associated with walking speed is important for identifying alterations in locomotor disorders caused by pathological processes, as opposed to those arising solely from altered speeds. METHODS: Fourteen healthy subjects were assessed walking at both natural and imposed cadences of 60, 80, and 120 steps/min. A 3D motion analysis system, force platforms, and related software were used to obtain kinematic and kinetic data. Net joint powers were calculated across cycles and the area under the positive and negative phases of the power curves provided the mechanical work generated and absorbed at the hip, knee, and ankle. The relative contributions to the total positive and negative work across the four cadences were calculated for each joint. ANOVAs followed by planned contrasts were used to assess the effects of laterality, joint, and cadence. FINDINGS: Power and mechanical work, as well as the contributions of individual joints to the total energy generated and absorbed, were shown to be influenced by walking cadence, independent of laterality. The ankle, knee, and hip contributions to the total limb generation and absorption at the lowest cadence were 53%, 21%, and 26%, and at the highest cadence, the corresponding values were 34%, 33%, and 33%, respectively. INTERPRETATION: Power and mechanical work, as well as the contributions of individual joints to the total energy generated and absorbed, were shown to be influenced by the walking cadence, independent of laterality. These findings will be helpful for identifying walking strategies and adaptations in populations with gait disorders.