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David C. Kingston and Stacey M. Acker

A musculoskeletal model of the right lower limb was developed to estimate 3D tibial contact forces in high knee flexion postures. This model determined the effect of intersegmental contact between thigh–calf and heel–gluteal structures on tibial contact forces. This model includes direct tracking and 3D orientation of intersegmental contact force, femoral translations from in vivo studies, wrapping of knee extensor musculature, and a novel optimization constraint for multielement muscle groups. Model verification consisted of calculating the error between estimated tibial compressive forces and direct measurements from the Grand Knee Challenge during movements to ∼120° of knee flexion as no high knee flexion data are available. Tibial compression estimates strongly fit implant data during walking (R 2 = .83) and squatting (R 2 = .93) with a root mean squared difference of .47 and .16 body weight, respectively. Incorporating intersegmental contact significantly reduced model estimates of peak tibial anterior–posterior shear and increased peak medial–lateral shear during the static phase of high knee flexion movements by an average of .33 and .07 body weight, respectively. This model supports prior work in that intersegmental contact is a critical parameter when estimating tibial contact forces in high knee flexion movements across a range of culturally and occupationally relevant postures.

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Seong-won Han, Andrew Sawatsky, Azim Jinha and Walter Herzog

Vastus medialis (VM) weakness is thought to alter patellar tracking, thereby changing the loading of the patellofemoral joint (PFJ), resulting in patellofemoral pain. However, it is challenging to measure VM force and weakness in human studies, nor is it possible to measure the associated mechanical changes in the PFJ. To obtain fundamental insight into VM weakness and its effects on PFJ mechanics, the authors determined PFJ loading in the presence of experimentally simulated VM weakness. Skeletally mature New Zealand White rabbits were used (n = 6), and the vastus lateralis, VM, and rectus femoris were stimulated individually through 3 custom-built nerve cuff electrodes. Muscle torque and PFJ pressure distribution were measured while activating all muscles simultaneously, or when the vastus lateralis and rectus femoris were activated, while VM was not, to simulate a quadriceps muscle strength imbalance. For a given muscular joint torque, peak pressures were greater and joint contact areas were smaller when simulating VM weakness compared with the condition where all muscles were activated simultaneously. The results in the rabbit model support that VM weakness results in altered PFJ loading, which may cause patellofemoral pain, often associated with a strength imbalance of the knee extensor muscle group.

Open access

Paige Guild, Monica R. Lininger and Meghan Warren

Clinical Scenario: Female college student-athletes (SA) often experience time loss from musculoskeletal injuries to the lower extremities. This can lead to lengthy rehabilitation, expensive medical bills, and declines in health-related quality of life. Identifying at-risk athletes prior to the start of an athletic season may allow coaches or athletic trainers to prescribe an injury prevention program. Clinical Question: In female college SA, are preseason single leg hop (SLH) scores associated with identifying those at risk for lower-extremity musculoskeletal injuries? Summary of Key Findings: Five prospective cohort studies in female SA scored athletes on the SLH prior to the start of the athletic sport season. One of 5 studies found an association of SLH with injury risk. An additional 2 studies found that the SLH as part of a battery of functional performance tests was associated with injury risk in some anatomic locations (eg, thigh/knee), but not overall injury risk. Clinical Bottom Line: Methodological limitations of the reviewed studies limits a final conclusion, and there is insufficient evidence to determine if the SLH should be used as a sole functional performance test to identify at-risk female SA; it may be useful as part of a battery of functional performance tests for female college SA. Strength of Recommendation: All studies were prospective cohort studies (level 3).

Open access

Kellie C. Huxel Bliven

Open access

Amanda L. Ager, Dorien Borms, Magali Bernaert, Vicky Brusselle, Mazarine Claessens, Jean-Sébastien Roy and Ann Cools

Context: Proprioception deficits contribute to persistent and recurring physical disability, particularly with shoulder disorders. Proprioceptive training is thus prescribed in clinical practice. It is unclear whether nonsurgical rehabilitation can optimize shoulder proprioception. Objectives: To summarize the available evidence of conservative rehabilitation (ie, nonsurgical) on proprioception among individuals with shoulder disorders. Evidence Acquisition: PubMed, Web of Science, and EBSCO were systematically searched, from inception until November 24, 2019. Selected articles were systematically assessed, and the methodological quality was established using the Dutch Cochrane Risk of Bias Tool and the Newcastle-Ottawa Quality Assessment Scale. The Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines were utilized for this review. The conservative treatments were categorized as follows: (1) conventional therapy, (2) proprioceptive training, (3) elastic kinesiology tape, and (4) other passive therapies. Evidence Synthesis: Twelve articles were included, yielding 58 healthy control shoulders and 362 shoulders affected by impingement syndrome, glenohumeral dislocations, nonspecific shoulder pain, rotator cuff dysfunction, or subluxation poststroke. The level of agreement between the evaluators was excellent (84.9%), and the studies were evaluated to be of fair to excellent quality (risk of bias: 28.5%–100%). This review suggests, with moderate evidence, that proprioceptive training (upper-body wobble board or flexible foil training) can improve proprioception in the midterm. No decisive evidence exists to suggest that conventional therapy is of added value to enhance shoulder proprioception. Conflicting evidence was found for the improvement of proprioception with the application of elastic kinesiology tape, while moderate evidence suggests that passive modalities, such as microcurrent electrical stimulation and bracing, are not effective for proprioceptive rehabilitation of the shoulder. Conclusions: Proprioceptive training demonstrates the strongest evidence for the effective rehabilitation of individuals with a shoulder proprioceptive deficit. Elastic kinesiology tape does not appear to affect the sense of shoulder proprioception. This review suggests a possible specificity of training effect with shoulder proprioception.

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Jim Potvin

Open access

Robert J. Gregor

Open access

Christopher Kevin Wong, Lizbeth Conway, Grant Fleming, Caitlin Gopie, Dara Liebeskind and Stephen Xue

Clinical Scenario: Many people with lower quarter musculoskeletal dysfunction present with muscle weakness. Strength training hypertrophies muscle and increases strength, but often requires periods over 6 weeks, which can exceed the episode of care. Weakness can persist despite muscle hypertrophy, particularly in the early stages of joint pathology or in the presence of limb or spinal joint hypomobility, which may inhibit muscle activation. Emerging evidence suggests spinal manipulation can increase short-term strength. Screening for specific muscle weakness that could benefit from manipulation to particular spinal segments could facilitate efficient clinical intervention. Although the neuromuscular mechanisms through which manipulation can increase strength remains a topic of investigation, immediate gains can benefit patients by jump-starting an exercise program to train new muscle function gained and enhancing the motivation to continue strengthening. Evidence from randomized controlled trials would provide support for using manipulation to increase muscle strength, while studying healthy people would eliminate confounding factors, such as pain and pathology. Clinical Question: Does randomized controlled trial-level evidence support the concept that a single lumbar spine manipulation session can increase lower-limb strength in healthy individuals? Summary of Key Findings: Level 1b evidence of moderate quality from 3 randomized controlled trials showed immediate small to large effect size muscle strength increases immediately after lumbar spine manipulation. Clinical Bottom Line: Lumbar spine manipulation can result in immediate lower-limb isometric strength increases. While healthy people with normal muscle strength may improve minimally, joint manipulation for people with knee and hip weakness who are otherwise healthy can result in large effect size strength gains. Strength of Recommendation: Moderate quality level 1b evidence from randomized controlled trials with small samples support the use of spinal manipulation to immediately increase lower-limb strength. Additional studies investigating impact on strength and function immediately in people with musculoskeletal pathology are warranted.

Open access

Caroline Lisee, Melanie L. McGrath, Christopher Kuenze, Ming Zhang, Matt Salzler, Jeffrey B. Driban and Matthew S. Harkey

Context: Ultrasound imaging is a clinically feasible tool to assess femoral articular cartilage and may have utility in tracking early knee osteoarthritis development. Traditional assessment techniques focus on measurements at a single location, which can be challenging to adopt for novice raters. Objective: To introduce a novel semiautomated ultrasound segmentation technique and determine the intrarater and interrater reliability of average regional femoral articular cartilage thickness and echo intensity of a novice and expert rater. Design: Descriptive observational study. Setting: Orthopedic clinic. Patients or Other Participants: Fifteen participants (mean [SD]; age 23.5 [4.6] y, height = 172.6 [9.3] cm, mass = 79.8 [15.7] kg) with a unilateral history of anterior cruciate ligament reconstruction participated. Intervention: None. Main Outcome Measures: One rater captured anterior femoral cartilage images of the participants’ contralateral knees using a transverse suprapatellar ultrasound assessment. The total femoral cartilage cross-sectional area of each image was segmented by a novice and expert rater. A novel custom program automatically separated the cartilage segmentations into medial, lateral, and intercondylar regions to determine the cross-sectional area and cartilage length. The average cartilage thickness in each region was calculated by dividing the cross-sectional area by the cartilage length. Echo intensity was calculated as the average gray-scale pixel value of each region. Two-way random effect intraclass correlations coefficient (ICC) for absolute agreement were used to determine the interrater reliability between a novice and expert rater, as well as the intrarater reliability of the novice rater. Results: The novice rater demonstrated excellent intrarater (ICC [2,k] range = .993–.997) and interrater (ICC [2,k] range = .944–.991) reliability with the expert rater of all femoral articular cartilage average thickness and echo intensity regions. Conclusions: The novel semiautomated average cartilage thickness and echo-intensity assessment is efficient, systematic, and reliable between an expert and novice rater with minimal training.

Open access

Kyung-Min Kim, Joo-Sung Kim, Jeonghoon Oh and Dustin R. Grooms

Context: The sensory organization test (SOT) is a standard for quantifying sensory dependence via sway-referenced conditions (sway-referenced support and sway-referenced vision [SRV]). However, the SOT is limited to expensive equipment. Thus, a practical version of the SOT is more commonly employed—the clinical test for sensory integration in balance; however, it fails to induce postural instability to the level of SRV. Objective: Determine if Stroboscopic vision (SV), characterized by intermittent visual blocking, may provide an alternative to the SRV for assessing postural stability. Design: Descriptive laboratory study. Setting: Research laboratory. Participants: Eighteen participants (9 males, 9 females; age = 22.1 [2.1] y, height = 169.8 [8.5] cm, weight = 66.5 [10.6] kg). Intervention: Participants completed the SOT conditions, and then repeated SOT conditions 2 and 5 with SV created by specialized eyewear. Main Outcome Measures: A repeated-measures analysis of variance was completed on the time-to-boundary metrics of center-of-pressure excursion in the anteroposterior and mediolateral directions in order to determine the difference between the full-vision, SV, and SRV conditions. Results: Postural stability with either SRV or SV was significantly worse than with full vision (P < .05), with no significant difference between SV and SRV (P > .05). Limits of agreement analysis revealed similar effects of SV and SRV except for unstable surface mediolateral time-to-boundary. Conclusions: In general, SV was found to induce a degree of postural instability similar to that induced by SRV, indicating that SV could be a portable and relatively inexpensive alternative for the assessment of sensory dependence and reweighting.