Diffusion tensor imaging of hamstring muscles after acute strain injury and throughout recovery in collegiate athletes.

OBJECTIVE: To identify the region of interest (ROI) to represent injury and observe between-limb diffusion tensor imaging (DTI) microstructural differences in muscle following hamstring strain injury. MATERIALS AND METHODS: Participants who sustained a hamstring strain injury prospectively underwent 3T-MRI of bilateral thighs using T1, T2, and diffusion-weighted imaging at time of injury (TOI), return to sport (RTS), and 12 weeks after RTS (12wks). ROIs were using the hyperintense region on a T2-weighted sequence: edema, focused edema, and primary muscle injured excluding edema (no edema). Linear mixed-effects models were used to compare diffusion parameters between ROIs and timepoints and limbs and timepoints. RESULTS: Twenty-four participants (29 injuries) were included. A significant ROI-by-timepoint interaction was detected for all diffusivity measures. The edema and focused edema ROIs demonstrated increased diffusion at TOI compared to RTS for all diffusivity measures (p-values < 0.006), except λ1 (p-values = 0.058-0.12), and compared to 12wks (p-values < 0.02). In the no edema ROI, differences in diffusivity measures were not observed (p-values > 0.82). At TOI, no edema ROI diffusivity measures were lower than the edema ROI (p-values < 0.001) but not at RTS or 12wks (p-values > 0.69). A significant limb-by-timepoint interaction was detected for all diffusivity measures with increased diffusion in the involved limb at TOI (p-values < 0.001) but not at RTS or 12wks (p-values > 0.42). Significant differences in fractional anisotropy over time or between limbs were not detected. CONCLUSION: Hyperintensity on T2-weighted imaging used to define the injured region holds promise in describing muscle microstructure following hamstring strain injury by demonstrating between-limb differences at TOI but not at follow-up timepoints.

Course Design and Learning Outcomes of a Practical Online Ergonomics Course for Surgical Residents.

OBJECTIVE: Course content was designed and the learning outcomes assessed for an online ergonomics course for surgical residents. This course could fulfill an optional Surgical Council on Resident Education (SCORE) curriculum on Surgical Ergonomics. DESIGN: The online course included five 5-minute modules within the residents' learning system, each ending with an ungraded knowledge question, and a final 5-question multiple-choice retention quiz that allowed infinite attempts. The course was designed by ergonomists and surgeons at a quaternary academic hospital system. Participants were given two weeks to complete the modules. An electronic survey with questions assessing ergonomics knowledge and understanding on a 5-point Likert scale (strongly disagree - strongly agree) was distributed both before and after the course. The post-course survey included three additional questions to elicit feedback regarding learning experience and course design. Descriptive statistics and nonparametric paired comparisons were used to evaluate learning outcomes. SETTING: General surgery residency program at an academic medical center in the U.S. PARTICIPANTS: Twenty-two general surgery post graduate year 1 residents (PGY1s) were recruited to participate and completed the pre-course survey. Eight out of the 22 participants (36%) completed the online course and quiz; seven (32%) completed the course, quiz, and the post-course survey. RESULTS: Participants had high pre-course awareness of the importance of surgical ergonomics, benefits of work-related musculoskeletal disorder (WMSD) prevention, as well as awkward intraoperative postures being an WMSD risk factor. Participants' confidence increased significantly from pre- to post-course in ability to assess risk (p = 0.021), but not in ability or willingness to mitigate risky surgical postures. Participants who completed the quiz answered a median of 4 (IQR: [4, 5]) questions correctly. All participants indicated that they would recommend this course to other residents. CONCLUSIONS: These short practical ergonomics online learning modules increased surgical residents' confidence in assessing surgical WMSD risks.

Vertical Loading Rate Is Not Associated with Running Injury, Regardless of Calculation Method.

INTRODUCTION: Loading rate (LR), the slope of the vertical ground reaction force (vGRF), is commonly used to assess running-related injury risk. However, the relationship between LR and running-related injuries, including bone stress injuries (BSI), is unclear. Inconsistent findings may result from the numerous LR calculation methods that exist and their application across different running speeds. PURPOSE: This study aimed to assess the influence of calculation method and running speed on LR values and to determine the association of LR during healthy running with subsequent injury. METHODS: Healthy preseason running data and subsequent injury records from Division I cross-country athletes ( n = 79) over four seasons (2015-2019) at 2.68 m·s -1 , preferred training pace, and 4.47 m·s -1 were collected. LR at each speed was calculated four ways: 1) maximum and 2) average slope from 20% to 80% of vGRF magnitude at impact peak (IP), 3) average slope from initial contact to IP, and 4) average slope from 3% to 12% of stance time. Linear mixed effects models and generalized estimation equations were used to assess LR associations. RESULTS: LR values differed depending on speed and calculation method ( P value <0.001). The maximum slope from 20% to 80% of the vGRF at 4.47 m·s -1 produced the highest LR estimate and the average slope from initial contact to IP at 2.68 m·s -1 produced the lowest. Sixty-four injuries (20 BSI) were observed. No significant association was found between LR and all injuries or BSI across any calculation method ( P values ≥0.13). CONCLUSIONS: Calculation method and running speed result in significantly different LR values. Regardless of calculation method, no association between LR and subsequent injury was identified. Thus, healthy baseline LR may not be useful to prospectively assess running-related injury risk.