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Edited by Tim L. Uhl

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Tim L. Uhl

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Nicole Cascia, Tim L. Uhl and Carolyn M. Hettrich

Clinical Scenario: Ulnar collateral ligament (UCL) injuries are highly prevalent in professional baseball players with the success of operative management being well known in the literature. Return to play (RTP) rates following nonoperative management of partial UCL injuries in professional baseball players are not well established in the literature. With a UCL tear being a potential career-ending injury, it is imperative that the best treatment option is provided to these throwing athletes. There is an increase in the incidence of UCL surgical rates and a lack of general agreement on nonoperative treatment of partial UCL injuries as reported by the American Shoulder and Elbow Surgeons in 2017. There is also a lack of clarity on when to initiate rehabilitation, which may be due to the limited amount of studies reporting success of RTP rates and time to RTP following conservative interventions of partial UCL injuries. Evidence on the RTP rates seen following conservative management of partial UCL tears injuries can help guide health care providers in deciding on the best treatment option for professional baseball athletes who desire to return to their athletic careers. These rates of RTP will add valuable objective input when determining if conservative management is the best choice. To determine the current evidence, inclusion criteria for the literature search consisted of RTP rates following conservative treatment in professional baseball players between inception and 2018. Clinical Question: Is there evidence for successful RTP rates in professional baseball players following conservative treatment of a UCL injury? Summary of Key Findings: Three retrospective studies met the inclusion criteria and were included. Of those, 2 reported RTP rates following a nonoperative rehabilitation program of a UCL injury, whereas 1 reported RTP rates after injection therapy in subjects who attempted a trial of conservative treatment. All 3 studies considered location and grade of UCL tear. Successful RTP rates (66%–100%) were reported in professional baseball players following nonoperative treatment of partial UCL injuries. Clinical Bottom Line: Current evidence supports high success with RTP rates up to 100% after nonoperative treatment of grade 1 UCL injuries in professional baseball players and between 66% and 94% for a grade 2 and above. Strength of Recommendation: There is level C evidence for high RTP rates following nonoperative treatment of partial UCL injuries in professional baseball players.

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Elizabeth Lawinger, Tim L. Uhl, Mark Abel and Srinath Kamineni

Objective:

The overarching goal of this study was to examine the use of triaxial accelerometers in measuring upper-extremity motions to monitor upper-extremity-exercise compliance. There were multiple questions investigated, but the primary objective was to investigate the correlation between visually observed arm motions and triaxial accelerometer activity counts to establish fundamental activity counts for the upper extremity.

Study Design:

Cross-sectional, basic research.

Setting:

Clinical laboratory.

Participants:

Thirty healthy individuals age 26 ± 6 y, body mass 24 ± 3 kg, and height 1.68 ± 0.09 m volunteered.

Intervention:

Participants performed 3 series of tasks: activities of daily living (ADLs), rehabilitation exercises, and passive shoulder range of motion at 5 specific velocities on an isokinetic dynamometer while wearing an accelerometer on each wrist. Participants performed exercises with their dominant arm to examine differences between sides. A researcher visually counted all arm motions to correlate counts with physical activity counts provided by the accelerometer.

Main Outcome Measure:

Physical activity counts derived from the accelerometer and visually observed activity counts recorded from a single investigator.

Results:

There was a strong positive correlation (r = .93, P < .01) between accelerometer physical activity counts and visual activity counts for all ADLs. Accelerometers activity counts demonstrated side-to-side difference for all ADLs (P < .001) and 5 of the 7 rehabilitation activities (P < .003). All velocities tested on the isokinetic dynamometer were shown to be significantly different from each other (P < .001).

Conclusion:

There is a linear relationship between arm motions counted visually and the physical activity counts generated by an accelerometer, indicating that arm motions could be potentially accounted for if monitoring arm usage. The accelerometers can detect differences in relatively slow arm-movement velocities, which is critical if attempting to evaluate exercise compliance during early phases of shoulder rehabilitation. These results provide fundamental information that indicates that triaxial accelerometers have the potential to objectively monitor and measure arm activities during rehabilitation and ADLs.

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Mario A. DiMattia, Ann L. Livengood, Tim L. Uhl, Carl G. Mattacola and Terry R. Malone

Context:

The Trendelenburg and single-leg-squat (SLS) tests are purported measures of hip-abduction strength that have not been previously validated.

Objective:

To correlate isometric hip-abduction strength to frontal-plane hip motion during an SLS and determine the criterion validity of a clinical-observation-analysis method to grade an SLS against 2-dimensional kinematic analysis.

Design:

Single-measure, concurrent validity.

Setting:

Biodynamics research laboratory.

Participants:

50 uninjured participants.

Main Outcome Measures:

Hip-abduction strength and hip and knee kinematic data during a Trendelenburg test and an SLS.

Results:

A weak, positive correlation between hip-abduction strength and hip-adduction angle was found during both the Trendelenburg (r = .22, P = .13) and the SLS (r = .21, P = .14) tests. The observation-analysis method revealed a low sensitivity, .23, and a higher specificity, .86, when compared with the kinematic data.

Conclusion:

The usefulness of the Trendelenburg and SLS test in screening hip-abductor strength in a healthy physically active population is limited. The origin of observable deficits during SLS requires further objective assessment.

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Brady L. Tripp and Tim L. Uhl

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Conrad M. Gabler, Adam S. Lepley, Tim L. Uhl and Carl G. Mattacola

Clinical Scenario:

Proper neuromuscular activation of the quadriceps muscle is essential for maintaining quadriceps (quad) strength and lower-extremity function. Quad activation (QA) failure is a common characteristic observed in patients with knee pathologies, defined as an inability to voluntarily activate the entire alpha-motor-neuron pool innervating the quad. One of the more popular techniques used to assess QA is the superimposed burst (SIB) technique, a force-based technique that uses a supramaximal, percutaneous electrical stimulation to activate all of the motor units in the quad during a maximal, voluntary isometric contraction. Central activation ratio (CAR) is the formula used to calculate QA level (CAR = voluntary force/SIB force) with the SIB technique. People who can voluntarily activate 95% or more (CAR = 0.95–1.0) of their motor units are defined as being fully activated. Therapeutic exercises aimed at improving quad strength in patients with knee pathologies are limited in their effectiveness due to a failure to fully activate the muscle. Within the past decade, several disinhibitory interventions have been introduced to treat QA failure in patients with knee pathologies. Transcutaneous electrical nerve stimulation (TENS) and cryotherapy are sensory-targeted modalities traditionally used to treat pain, but they have been shown to be 2 of the most successful treatments for increasing QA levels in patients with QA failure. Both modalities are hypothesized to positively affect voluntary QA by disinhibiting the motor-neuron pool of the quad. In essence, these modalities provide excitatory afferent stimuli to the spinal cord, which thereby overrides the inhibitory afferent signaling that arises from the involved joint. However, it remains unknown whether 1 is more effective than the other for restoring QA levels in patients with knee pathologies. By knowing the capabilities of each disinhibitory modality, clinicians can tailor treatments based on the rehabilitation goals of their patients.

Focused Clinical Question:

Is TENS or cryotherapy the more effective disinhibitory modality for treating QA failure (quantified via CAR) in patients with knee pathologies?

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Brianna M. Papotto, Thomas Rice, Terry Malone, Timothy Butterfield and Tim L. Uhl

Context: Shoulder external rotators are challenged eccentrically throughout the deceleration phase of throwing, which is thought to contribute to overuse injuries. To evaluate the effectiveness of intervention programs, as well as identifying deficits, reliable and responsive measures of isometric and eccentric shoulder external rotation are necessary. Previously, isometric measures have primarily tested a single position, and eccentric measures have not been found to have high reliability. Objective: To examine the between-days reliability of multiple-angle isometric and dynamic eccentric isokinetic testing of shoulder external rotation. Design: Repeated measures. Participants: 10 healthy subjects (age 30 ± 12 y, height 166 ± 13 cm, mass 72 ± 10 kg). Main Outcome Measures: Average isometric peak torque of shoulder external rotation at 7 angles was measured. From these values, the angle of isometric peak torque was calculated. Dynamic eccentric average peak torque, average total work, and average angle of peak torque were measured. Results: Between-days reliability was high for average peak torque during isometric contractions at all angles (ICC ≥ .85), as it was for dynamic eccentric average peak torque (ICC ≥ .97). The estimated angle of isometric peak torque (ICC ≤ .65) was not highly reliable between days. The average angle of peak torque from the eccentric testing produced inconsistent results. Average total work of dynamic eccentric shoulder external rotation was found to be highly reliable between days (ICC ≥ . 97). Conclusion: Aspects of force such as peak torque and total work in isometric and eccentric testing of the shoulder external-rotator muscles can be measured reliably between days and used to objectively evaluate shoulder strength and identify changes when they occur. Angle measurements of peak torque could provide insight into the mechanical properties of the posterior shoulder muscles but were found to be inconsistent between days.

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Christopher Melton, David R. Mullineaux, Carl G. Mattacola, Scott D. Mair and Tim L. Uhl

Context:

Dynamic shoulder motion can be captured using video capture systems, but reliability has not yet been established.

Objective:

To compare the reliability of 2 systems in measuring dynamic shoulder kinematics during forward-elevation movements and to determine differences in these kinematics between healthy and injured subjects.

Design:

Reliability and cohort.

Setting:

Research laboratory.

Participants:

11 healthy subjects and 10 post–superior labrum anteroposterior lesion patients (SLAP).

Intervention:

Contrasting markers were placed at the hip, elbow, and shoulder to represent shoulder elevation and were videotaped in 2 dimensions. Subjects performed 6 repetitions of active elevation (AE) and active assisted elevation of the shoulder, and 3 trials were analyzed using Datapac (comprehensive system) and Dartfish (basic system).

Main Outcome Measures:

Amplitudes and velocities of the shoulder angle were calculated. Intraclass correlation coefficient (ICC), standard error of measurement (SEM), and levels of agreement (LOA) were used to determine intersystem and intertrial reliability.

Results:

For AE, the amplitude maximum (ICC = .98–.99, SEM = 2–3°, LOA = −9° to 5°) and average velocity (ICC = .94–.97, SEM = 1°/s, LOA = −4° to 1°/s) indicated excellent intersystem reliability between systems. Intratrial reliability for minimum velocity was moderate for Datapac (ICC = .64, SEM = 4°/s, LOA = 7°/s) and poor for Dartfish (ICC = .52, SEM = 20°/s, LOA = 37°/s). Cohort results demonstrated for AE a greater amplitude for healthy v SLAP (139° ± 11° v 113° ± 13°; P = .001) and interaction for an average velocity increase of 2°/s in healthy and decrease of 2°/s in SLAP patients over the 3 trials (P = .02).

Conclusions:

Reliability ranges provide the means to assess the clinical meaningfulness of results. The cohort differences are supported when the values exceed the ranges of the SEM; hence the amplitude results are meaningful. For dynamic shoulder elevation measured using video, the assessment of velocity was found to produce moderate to good reliability. The results suggest that with these measures subtle changes in both measures may be possible with further investigations.

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Ann L. Livengood, Mario A. DiMattia and Tim L. Uhl

Column-editor : Carl G. Mattacola