Joint Coordination and Stiffness During Landing in Individuals With Chronic Ankle Instability.

The purpose of the present study was to examine the effect of chronic ankle instability (CAI) on lower-extremity joint coordination and stiffness during landing. A total of 21 female participants with CAI and 21 pair-matched healthy controls participated in the study. Lower-extremity joint kinematics were collected using a 7-camera motion capture system, and ground reaction forces were collected using 2 force plates during drop landings. Coupling angles were computed based on the vector coding method to assess joint coordination. Coupling angles were compared between the CAI and control groups using circular Watson-Williams tests. Joint stiffness was compared between the groups using independent t tests. Participants with CAI exhibited strategies involving altered joint coordination including a knee flexion dominant pattern during 30% and 70% of their landing phase and a more in-phase motion pattern between the knee and hip joints during 30% and 40% and 90% and 100% of the landing phase. In addition, increased ankle inversion and knee flexion stiffness were observed in the CAI group. These altered joint coordination and stiffness could be considered as a protective strategy utilized to effectively absorb energy, stabilize the body and ankle, and prevent excessive ankle inversion. However, this strategy could result in greater mechanical demands on the knee joint.

Lower limb kinematics of unicompartmental knee arthroplasty individuals during stair ascent.

OBJECTIVE: Purpose of the study was to compare lower-limb kinematics and interlimb asymmetry during stair ascent in individuals post-medial or lateral unicompartmental knee arthroplasty (UKA). METHODS: 60 patients (20 medial; 10 lateral) post-UKA and 30 matched healthy controls performed stair ascent. Spatio-temporal, lower-limb kinematics and interlimb asymmetries during stair ascent were compared. RESULTS: Medial-UKA group displayed 5° less knee extension of the UKA limb than controls (p = 0.005) and 2° less than the contralateral limb during stance phase. No interlimb asymmetries were found for lateral-UKA. CONCLUSION: Patients post-UKA demonstrate satisfactory lower-limb kinematics and minimal interlimb asymmetry during stair ascent compared to healthy individuals.

Cross-cultural adaptation and validation of an ankle instability questionnaire for use in Chinese-speaking population.

BACKGROUND: The Identification of Functional Ankle Instability (IdFAI) is a valid and reliable tool to identify chronic ankle instability; however, it was developed in English, thus limiting its usage only to those who can read and write in English. The objectives of our study were to (1) cross-culturally adapt a Chinese (Mandarin) version of the IdFAI and (2) determine the psychometric properties of the Chinese version IdFAI. METHODS: The cross-cultural adaptation procedures used by the investigators and translators followed previously published guidelines and included 6 stages: (1) initial translation, (2) synthesis of the translations, (3) back translation, (4) developing the pre-final version for field testing, (5) testing the pre-final version, and (6) finalizing the Chinese version of IdFAI (IdFAI-C). Five psychometric properties of the IdFAI-C were assessed from results of 2 participant groups: bilingual (n = 20) and Chinese (n = 625). RESULTS: A high degree of agreement was found between the English version of IdFAI and IdFAI-C (intra-class correlation2,1 = 0.995). An excellent internal consistency (Cronbach's α = 0.89), test-retest reliability (intra-class correlation2,1 = 0.970), and construct validity (r(625) = 0.67) was also found for the IdFAI-C. In addition, the results of exploratory and confirmatory factor analysis indicated that ankle instability was the only construct measured from the IdFAI. CONCLUSION: The IdFAI-C is a highly reliable and valid self-report questionnaire that can be used to assess ankle instability. Therefore, we suggest that it can be used to effectively and accurately assess chronic ankle instability in clinical settings for Chinese-speaking individuals.

Chronic Ankle Instability Does Not Influence Tibiofemoral Contact Forces During Drop Landings Using a Musculoskeletal Model.

The purpose of the study was to compare the tibiofemoral contact forces of participants with chronic ankle instability versus controls during landings using a computer-simulated musculoskeletal model. A total of 21 female participants with chronic ankle instability and 21 pair-matched controls performed a drop landing task on a tilted force plate. A 7-camera motion capture system and 2 force plates were used to test participants' lower-extremity biomechanics. A musculoskeletal model was used to calculate the tibiofemoral contact forces (femur on tibia). No significant between-group differences were observed for the peak tibiofemoral contact forces (P = .25-.48) during the landing phase based on paired t tests. The group differences ranged from 0.05 to 0.58 body weight (BW). Most participants demonstrated a posterior force (peak, ∼1.1 BW) for most duration of the landing phase and a medial force (peak, ∼0.9 BW) and large compressive force (peak, ∼10 BW) in the landing phase. The authors conclude that chronic ankle instability may not be related to the increased tibiofemoral contact forces or knee injury mechanisms during landings on the tilted surface.

Biomechanics of ankle giving way: A case report of accidental ankle giving way during the drop landing test.

BACKGROUND: Several case studies observed that the lateral ankle sprain resulted from a sudden increase in ankle inversion accompanied by internal rotation. However, without sufficient ankle kinetics and muscle activity information in the literature, the detailed mechanism of ankle sprain is still unrevealed. The purpose of our case report is to present 2 accidental ankle giving way incidents for participants with chronic ankle instability (CAI) and compare to their normal trials with data of kinematics, kinetics, and electromyography (EMG). CASE DESCRIPTION: Two young female participants accidentally experienced the ankle giving way when landing on a 25° lateral-tilted force plate. 3D kinematics, kinetics, and muscle activity were recorded for the lower extremity. Qualitative comparisons were made between the giving way trials and normal trials for joint angles, angular velocities, moments, centers of pressure and EMG linear envelopes. RESULTS: One participant's giving way trial displayed increased ankle inversion and internal rotation angles in the pre-landing phase and at initial contact compared to her normal trials. Another participant's giving way trial exhibited greater hip abduction angles and delayed activation of the peroneus longus muscle in the pre-landing phase versus her normal trials. CONCLUSION: A vulnerable ankle position (i.e., more inverted and internally rotated), and a late activation of peroneus activity in the pre-landing phase could result in the ankle giving way or even sprains. A neutral ankle position and early activation of ankle evertors before landing may be helpful in preventing ankle sprains.

Spine and Lower Extremity Kinematics Exhibited During Running by Adolescent Idiopathic Scoliosis Patients With Spinal Fusion.

STUDY DESIGN: Case-controlled design; biomechanics laboratory setting. OBJECTIVE: To compare the spine and lower extremity kinematics displayed during high-effort running between individuals with spinal fusion surgery for adolescent idiopathic scoliosis (SF-AIS) and healthy controls (CON). SUMMARY OF BACKGROUND DATA: Individuals with SF-AIS often return to exercise and sports that include running. However, how these individuals produce the spinal rotations needed during high-effort running and thus compensate for the loss of spinal flexibility is not known. METHODS: Ten SF-AIS (posterior-approach spinal fusion; postoperative time: 2.0 ± 0.6 years; physically active) and 10 CON individuals, pair-matched for gender, age, mass, height, and level of physical activity participated. SF-AIS individuals ran on a treadmill at a self-selected submaximal speed perceived as "hard" (15/20 on Borg perceived-effort scale), and CON ran at the SF-AIS pair-matched speed. 3D motion capture system was used to generate trunk and pelvis segmental angles (trunk segments = upper trunk [C7-T8], middle trunk [T9-T12], lower trunk [L1-L5]), relative angles (relative angles between the two consecutive trunk segments), and lower extremity joint angles. The group differences between the SF-AIS and CON were assessed using one-way analysis of covariance (with running speed as the covariate) for trunk, lower extremity, and step kinematics. RESULTS: SF-AIS participants exhibited a significantly greater (6.1° greater) lower trunk and (6.3° greater) pelvis segmental axial rotation compared with CON during running. In addition, SF-AIS participants displayed a 9.2° less ankle plantarflexion during the support phase. There were no significant differences detected for step kinematics. CONCLUSION: Possibly because of relearned compensatory mechanism, individuals with SF-AIS displayed similar patterns of spine, lower extremity, and step kinematics as healthy controls during high-effort running with some exceptions. LEVEL OF EVIDENCE: Level III.

Postural control of individuals with spinal fusion for adolescent idiopathic scoliosis.

BACKGROUND: The purpose of the study was to assess the postural stability and complexity of postural control for moderately physically active individuals with spinal fusion for adolescent idiopathic scoliosis at two years post-operation. METHODS: Limit of stability test and sensory organization test were conducted for 10 moderately physically-active participants with spinal fusion and 10 controls pair-matched for mass, height and physical activity level. During the limit of stability test, participants were instructed to lean the center of gravity as far as possible toward 8 predetermined directions and the maximum excursion and direction control were analyzed. During the sensory organization test, participants were instructed to maintain as still as possible in six test conditions and equilibrium scores and sway area of center of pressure were analyzed. Multi-scale entropy of center of pressure was calculated to quantify sway complexity. FINDINGS: Most postural stability outcomes of spinal fusion participants were comparable to controls except for significantly reduced equilibrium scores (p = 0.039, partial η2 = 0.217). Moreover, spinal fusion participants exhibited tendencies of reduced direction control (p = 0.053) during the limit of stability test and greater sway area (p = 0.052) during the sensory organization test. INTERPRETATION: Although the center of gravity control might be affected, spinal fusion individuals who were moderately physically active likely progressively learned to adapt postoperatively to their fused spine to meet the postural demands required when performing physical movements. We suggest that spinal fusion is a satisfactory treatment in regard to the recovery of postural stability.

Knee strength, power and stair performance of the elderly 5 years after unicompartmental knee arthroplasty.

BACKGROUND: Unicompartmental knee arthroplasty (UKA) has been shown to demonstrate some satisfactory short-term outcomes. However, to our knowledge, there have been no reports on midterm or long-term knee extensor strength and leg extensor power post-UKA. AIMS: Therefore, the purposes of this study were: (1) to assess the isokinetic knee extensor strength, leg extensor power and stair performance of elderly participants at 5 years UKA post-operation; (2) to compare the differences in knee extensor strength and leg extensor power between the UKA and contralateral healthy limbs. METHODS: Nineteen elderly participants (75 ± 5 years) who had a medial or a lateral compartment UKA at 5 years post-operation were recruited. The isokinetic knee extensor strength and leg extensor power were measured. The stair performance was tested on a 4-step stair, and ascent and descent velocities were calculated. The pain level was assessed. RESULTS: The UKA limbs' knee extensor strength and leg extensor power were 1.01 ± 0.39 Nm/kg and 0.98 ± 0.27 W/kg, respectively. The stair ascent and descent velocities were 0.37 ± 0.07 and 0.38 ± 0.11 m/s, respectively. In addition, the UKA limbs exhibited comparable knee strength and leg power relative to the contralateral limbs. DISCUSSION: In general, the knee extensor strength and leg extensor power exhibited by the UKA limbs at 5 years post-operation may be typical in comparison with the normative data. CONCLUSIONS: We suggest that UKA is a satisfactory treatment in regard to the recovery of knee strength, leg power and ability to climb up and down stairs.

Upper Trunk-Pelvis Coordination During Running Using the Continuous Relative Fourier Phase Method.

The upper trunk-pelvic coordination patterns used in running are not well understood. The purposes of this study are to (1) test the running speed effect on the upper trunk-pelvis axial rotation coordination and (2) present a step-by-step guide of the relative Fourier phase algorithm, as well as some further issues to consider. A total of 20 healthy young adults were tested under 3 treadmill running speeds using a 3-dimensional motion capture system. The upper trunk and pelvic segmental angles in axial rotation were calculated, and the coordination was quantified using the relative Fourier phase method. Results of multilevel modeling indicated that running speed did not significantly contribute to the changes in coordination in a linear pattern. A qualitative template analysis suggested that participants displayed different change patterns of coordination as running speed increased. Participants did not significantly change the upper trunk and pelvis coordination mode in a linear pattern at higher running speeds, possibly because they employed different motion strategies to achieve higher running speeds and thus displayed large interparticipant variations. For most of our runners, running at a speed deviated from the preferred speed could alter the upper trunk-pelvis coordination. Future studies are still needed to better understand the influence of altered coordination on running performance and injuries.

Does chronic ankle instability influence lower extremity muscle activation of females during landing?

Much remains unclear about how chronic ankle instability (CAI) could affect knee muscle activations and interact with knee biomechanics. Therefore, the purpose of this study was to assess the influence of CAI on the lower extremity muscle activation at the ankle and knee joints during landings on a tilted surface. A surface electromyography system and two force plates were used to collect lower extremity muscle activation of 21 young female individuals with CAI and 21 pair-matched controls during a double-leg landing with test limb landing on the tilted surface. In the pre-landing phase, compared to controls, CAI participants displayed a reduced ankle evertor activation that could place CAI at a high risk of giving way or sprain injury. In the landing phase, an increased tibialis anterior activation of CAI led to increased co-contraction of ankle muscles in the sagittal and frontal plane. A greater ankle muscle co-contraction could increase the ankle stability during landings but may adversely influence the knee muscle activations (e.g., a greater co-contraction ratio of quadriceps to hamstrings). Relevant training programs (e.g., increasing pre-landing peroneal activation, and optimizing activation ratio of quadriceps to hamstrings) may help individuals with CAI improving ankle stability and reduce atypical knee loading during landings.

Spine kinematics exhibited during the stop-jump by physically active individuals with adolescent idiopathic scoliosis and spinal fusion.

BACKGROUND CONTEXT: Individuals with adolescent idiopathic scoliosis post spinal fusion often return to exercise and sport. However, the movements that individuals with spinal fusion for adolescent idiopathic scoliosis (SF-AIS) use to compensate for the loss of spinal flexibility during high-effort tasks are not known. PURPOSE: The objective of this study was to compare the spinal kinematics of the trunk segments displayed during the stop-jump, a maximal effort task, between SF-AIS and healthy control groups. STUDY DESIGN: The study used a case-controlled design. MATERIALS AND METHODS: Ten SF-AIS (physically active, posterior-approach spinal fusion: 11.2±1.9 fused segments, postop time: 2±.6 years) and nine control individuals, pair matched for gender, age (17.4±1.3 years and 20.6±1.5 years, respectively), mass (63.50±12.2 kg and 66. 40±10.9 kg), height (1.69±.09 m and 1.72±.08 m), and level of physical activity, participated in the study. Individuals with spinal fusion for adolescent idiopathic scoliosis and controls (CON) performed five acceptable trials of the stop-jump task. Spatial locations of 21 retroreflective trunk and pelvis markers were recorded via high-speed motion capture methodology. Mean differences and analysis of covariance (jump height=covariate, p<.05) were used to compare the groups' relative angle (RelAng) and segmental angle (SegAng) of the three trunk segments (trunk segments=upper trunk [C7-T8], middle trunk [MT: T9-T12], lower trunk [LT: L1-L5]) for each rotation plane in the three phases of interest (flight, stance, and the vertical flight phases). RESULTS: No significant group differences for jump height and RelAng were detected in the three phases of stop-jump. Individuals with spinal fusion for adolescent idiopathic scoliosis displayed 3.2° greater transverse plane RelAng of LT compared with CON (p=.059) in the stance phase. Group differences for RelAng ranged from 0° to 15.3°. For SegAng in the stance phase, LT demonstrated greater SegAng in the sagittal and frontal planes (mean difference: 3.2°-6.2°), whereas SegAng for MT was 5.1° greater in the sagittal plane and had a tendency of 2° greater displacement in the frontal plane (p=.070). In the vertical flight phase, greater LT displacement in the frontal plane was observed for SF-AIS than CON. In the flight phase, LT had a tendency for greater SegAng for SF-AIS than for CON in the transverse plane (p=.089). CONCLUSIONS: Overall, SF-AIS who participate in physical activity on a regular basis are able to demonstrate similar trunk kinematics during a high-intensity stop-jump task as their matched healthy peers. Fewer group differences for relative angular displacements of the spine were observed than anticipated. This finding suggests that the fused MT appeared to be moving synchronously with the LT, thereby suggesting a compensatory adaptation of SF-AIS to achieve sufficient trunk movements during this high-effort movement.

Lower extremity kinematics of curve sprinting displayed by runners using a transtibial prosthesis.

The purpose of the study was to determine if the kinematics exhibited by skilled runners wearing a unilateral, transtibial prosthesis during the curve section of a 200-m sprint race were influenced by interaction of limb-type (prosthetic limb (PROS-L) vs. nonprosthetic limb (NONPROS-L)) and curve-side (inside and outside limb relative to the centre of the curve). Step kinematics, toe clearance and knee and hip flexion/extension, hip ab/adduction for one stride of each limb were generated from video of 13 males running the curve during an international 200 m transtibial-classified competition. Using planned comparisons (P < 0.05), limb-type and curve-side interactions showed shortest support time and lowest hip abduction displacement by outside-NONPROS-L; shortest step length and longest time to peak knee flexion by the inside-PROS-L. For limb-type, greater maximum knee flexion angle and lower hip extension angles and displacement during support and toe clearance of PROS-Ls occurred. For curve-side, higher hip abduction angles during non-support were displayed by inside-limbs. Therefore, practitioners should consider that, for curve running, these kinematics are affected mostly by PROS-L limitations, with no clear advantage of having the PROS-L on either side of the curve.

Intratrunk Coordination During High-Effort Treadmill Running in Individuals With Spinal Fusion for Adolescent Idiopathic Scoliosis.

The purpose of the study was to determine if the intratrunk coordination of axial rotation exhibited by individuals with spinal fusion for adolescent idiopathic scoliosis (SF-AIS) during running varies from healthy individuals and how the coordination differs among adjacent trunk-segment pairs. Axial rotations of trunk segments (upper, middle, lower trunk) and pelvis were collected for 11 SF-AIS participants and 11 matched controls during running. Cross-correlation determined the phase lag between the adjacent segment motions. The coupling angle was generated using the vector coding method and classified into 1 of the 4 major, modified coordination patterns: in-phase, anti-phase, superior, and inferior phase. Two-way, mixed-model ANCOVA was employed to test phase lag, cross-correlation r, and time spent in each major coordination pattern. A significantly lower phase lag for SF-AIS was observed compared with controls. Qualitatively, there was a tendency that SF-AIS participants spent less time in anti-phase for middle-lower trunk and lower trunk-pelvis coordinations compared to controls. Phase lag and anti-phase time was significantly increased from cephalic to caudal segment pairs, regardless of group. In conclusion, SF-AIS participants and controls displayed similar patterns of intra-trunk coordination; however, the spinal fusion hindered decoupling of intra-trunk motions particularly between the lower trunk-pelvic motion.

Review of Physical Activity Benefits and Potential Considerations for Individuals with Surgical Fusion of Spine for Scoliosis.

Evidence-based recommendations for physical activity following spinal fusion surgeries for idiopathic scoliosis are limited, specifically in the adolescent population. Individuals with scoliosis treated operatively or non-operatively have been reported to participate in less than 1-3 days/week of even mildly strenuous physical exercises. Over 40% of individuals with scoliosis returned to sports at a level lower than pre-operative participation levels or did not return at all post spinal fusion. It is particularly important for human movement specialists, such as physical therapists, occupational therapists, athletic trainers and kinesiologists to assist these individuals effectively transition to and maintain engagement in physical activity. This review provides a snapshot of common considerations and potential factors influencing individuals with spinal-fusion for scoliosis to participate in safe physical activity.

Patellar tendon straps decrease pre-landing quadriceps activation in males with patellar tendinopathy.

OBJECTIVE: To determine if patellar tendon straps altered quadriceps' muscle activity during a drop-jump landing in males with and without patellar tendinopathy. DESIGN: Case-control. SETTINGS: Biomechanics Research Laboratory. PARTICIPANTS: Twenty recreationally-active males participated: ten (age = 21.3 ± 2.4 years, height = 182.8 ± 5.3 cm, mass = 81.7 ± 8.6 kg) with patellar tendinopathy; ten (age = 22.0 ± 1.6 years, height = 185.7 ± 4.5 cm, mass = 82.2 ± 9.8 kg) were healthy with no history of tendinopathy. MAIN OUTCOME MEASURES: Electromyography (EMG) data for the vastus medialis (VM), rectus femoris (RF), and vastus lateralis (VL) muscles were collected. Five 2-legged 40 cm drop-jumps were performed wearing a patellar tendon strap and 5 with no-strap in a counterbalanced order. Root-mean square EMG (REMG) values of the VM, RF, and VL were averaged for a pre-landing and post-landing interval. Multiple mixed-model two-way ANOVAs were performed to determine the effect of tendinopathy and strapping condition on REMG values for each muscle. RESULTS: For the pre-landing interval, all participants displayed lesser VL EMG activation (0.44 ± 0.19%, 0.53 ± 0.27%, respectively; p = 0.007, d = 0.39) in the no-strap compared with the strap condition. CONCLUSIONS: When wearing a strap, all participants demonstrated lower VL activation prior to landing which may be helpful in reducing tensile stress at the tendon. These effects may be clinically important in modulating pain in those with patellar tendinopathy.

Concussion History and Time Since Concussion Do not Influence Static and Dynamic Balance in Collegiate Athletes.

CONTEXT: Dynamic balance deficits exist following a concussion, sometimes years after injury. However, clinicians lack practical tools for assessing dynamic balance. OBJECTIVES: To determine if there are significant differences in static and dynamic balance performance between individuals with and without a history of concussion. DESIGN: Cross sectional. SETTING: Clinical research laboratory. PATIENTS OR OTHER PARTICIPANTS: 45 collegiate student-athletes with a history of concussion (23 males, 22 females; age = 20.0 ± 1.4 y; height = 175.8 ± 11.6 cm; mass = 76.4 ± 19.2 kg) and 45 matched controls with no history of concussion (23 males, 22 females; age = 20.0 ± 1.3 y; height = 178.8 ± 13.2 cm; mass = 75.7 ± 18.2 kg). INTERVENTIONS: Participants completed a static (Balance Error Scoring System) and dynamic (Y Balance Test-Lower Quarter) balance assessment. MAIN OUTCOME MEASURES: A composite score was calculated from the mean normalized Y Balance Test-Lower Quarter reach distances. Firm, foam, and overall errors were counted during the Balance Error Scoring System by a single reliable rater. One-way ANOVAs were used to compare balance performance between groups. Pearson's correlations were performed to determine the relationship between the time since the most recent concussion and balance performance. A Bonferonni adjusted a priori α < 0.025 was used for all analyses. RESULTS: Static and dynamic balance performance did not significantly differ between groups. No significant correlation was found between the time since the most recent concussion and balance performance. CONCLUSIONS: Collegiate athletes with a history of concussion do not present with static or dynamic balance deficits when measured using clinical assessments. More research is needed to determine whether the Y Balance Test-Lower Quarter is sensitive to acute balance deficits following concussion.

Lower Extremity Kinematics During a Drop Jump in Individuals With Patellar Tendinopathy.

BACKGROUND: Patellar tendinopathy (PT) is a common degenerative condition in physically active populations. Knowledge regarding the biomechanics of landing in populations with symptomatic PT is limited, but altered mechanics may play a role in the development or perpetuation of PT. PURPOSE: To identify whether study participants with PT exhibited different landing kinematics compared with healthy controls. STUDY DESIGN: Controlled laboratory study. METHODS: Sixty recreationally active participants took part in this study; 30 had current signs and symptoms of PT, including self-reported pain within the patellar tendon during loading activities for at least 3 months and ≤80 on the Victorian Institute of Sport Assessment Scale-Patella (VISA-P). Thirty healthy participants with no history of PT or other knee joint pathology were matched by sex, age, height, and weight. Participants completed 5 trials of a 40-cm, 2-legged drop jump followed immediately by a 50% maximum vertical jump. Dependent variables of interest included hip, knee, and ankle joint angles at initial ground contact, peak angles, and maximum angular displacements during the landing phase in 3 planes. Independent-samples t tests (P ≤ .05) were utilized to compare the joint angles and angular displacements between PT and control participants. RESULTS: Individuals with PT displayed significantly decreased peak hip (PT, 59.2° ± 14.6°; control, 67.2° ± 13.9°; P = .03) and knee flexion angles (PT, 74.8° ± 13.2°; control, 82.5° ± 9.0°; P = .01) compared with control subjects. The PT group displayed decreased maximum angular displacement in the sagittal plane at the hip (PT, 49.3° ± 10.8°; control, 55.2° ± 11.4°; P = .04) and knee (PT, 71.6° ± 8.4°; control, 79.7° ± 8.3°; P < .001) compared with the control group. CONCLUSION: Participants with PT displayed decreased maximum flexion and angular displacement in the sagittal plane, at both the knee and the hip. The altered movement patterns in those with PT may be perpetuating symptoms associated with PT and could be due to the contributions of the rectus femoris during dynamic movement. CLINICAL RELEVANCE: Based on kinematic alterations in symptomatic participants, rehabilitation efforts may benefit from focusing on both the knee and the hip to treat symptoms associated with PT.

Sit-to-stand biomechanics of individuals with multiple sclerosis.

BACKGROUND: It is unclear how people with multiple sclerosis, who often have compromised strength and balance, compare to healthy controls during sit-to-stand movements. The purpose of this study was to compare sit-to-stand biomechanics among three groups: people with multiple sclerosis who exhibit leg weakness, people with multiple sclerosis who have comparable strength to controls, and healthy controls. METHODS: Twenty-one individuals with multiple sclerosis (n=10 exhibiting leg weakness: n=11 exhibiting comparable strength to controls), and 12 controls performed five sit-to-stand trials while kinematic data and ground reaction forces were captured. ANOVAs followed by Tukey's post-hoc tests (α=0.05) were used to determine group and limb differences for leg strength, movement time, and sagittal-plane joint kinematics and kinetics. FINDINGS: Persons with multiple sclerosis exhibiting leg weakness displayed decreased leg strength, greater trunk flexion, faster trunk flexion velocity and decreased knee extensor power compared to the other two groups (p<0.05; d≥0.87), and slower rise times compared to controls(p<0.03; d≥1.17). No differences were found between controls and the multiple sclerosis-comparable strength group. Across all 3 groups, leg strength was moderately correlated with trunk kinematics and knee extensor velocities, moments and powers of the sit-to-stand (p≤0.05). INTERPRETATION: Participants with multiple sclerosis exhibiting leg weakness took longer to stand and appeared to use a trunk-flexion movement strategy when performing the sit-to-stand. The majority of group differences appear to be a result of leg extension weakness. Treatment that includes leg strengthening may be necessary to improve sit-to-stand performance for people with multiple sclerosis.

Automated detection of physiologic deterioration in hospitalized patients.

OBJECTIVE: Develop and evaluate an automated case detection and response triggering system to monitor patients every 5 min and identify early signs of physiologic deterioration. MATERIALS AND METHODS: A 2-year prospective, observational study at a large level 1 trauma center. All patients admitted to a 33-bed medical and oncology floor (A) and a 33-bed non-intensive care unit (ICU) surgical trauma floor (B) were monitored. During the intervention year, pager alerts of early physiologic deterioration were automatically sent to charge nurses along with access to a graphical point-of-care web page to facilitate patient evaluation. RESULTS: Nurses reported the positive predictive value of alerts was 91-100% depending on erroneous data presence. Unit A patients were significantly older and had significantly more comorbidities than unit B patients. During the intervention year, unit A patients had a significant increase in length of stay, more transfers to ICU (p = 0.23), and significantly more medical emergency team (MET) calls (p = 0.0008), and significantly fewer died (p = 0.044) compared to the pre-intervention year. No significant differences were found on unit B. CONCLUSIONS: We monitored patients every 5 min and provided automated pages of early physiologic deterioration. This before-after study found a significant increase in MET calls and a significant decrease in mortality only in the unit with older patients with multiple comorbidities, and thus further study is warranted to detect potential confounding. Moreover, nurses reported the graphical alerts provided information needed to quickly evaluate patients, and they felt more confident about their assessment and more comfortable requesting help.

The effects of a lateral in-flight perturbation on lower extremity biomechanics during drop landings.

One potential ACL injury situation is due to contact with another person or object during the flight phase, thereby causing the person to land improperly. Conversely, athletes often have flight-phase collisions but do land safely. Therefore, to better understand ACL injury causation and methods by which people typically land safely, the purpose of this study was to determine the effects of an in-flight perturbation on the lower extremity biomechanics displayed by females during typical drop landings. Seventeen collegiate female recreational athletes performed baseline landings, followed by either unexpected laterally-directed perturbation or sham (nonperturbation) drop landings. We compared baseline and perturbation trials using paired-samples t tests (P < .05) and 95% confidence intervals for lower-extremity joint kinematics and kinetics and GRF. The results demonstrated that perturbation landings compared with baseline landings exhibited more extended joint positions of the lower extremity at initial contact; and, during landing, greater magnitudes for knee abduction and hip adduction displacements; peak magnitudes of vertical and medial GRF; and maximum moments of ankle extensors, knee extensors, and adductor and hip adductors. We conclude that a lateral in-flight perturbation leads to abnormal GRF and angular motions and joint moments of the lower extremity.