Michael D. Clark

Modic Changes on MR Images as Studied with Provocative Diskography: Clinical Relevance—A Retrospective Study of 2457 Disks

PURPOSE To assess the value of vertebral body endplate signal intensity (Modic) changes on magnetic resonance (MR) images in predicting a painful disk, with provocative diskography as the reference standard. MATERIALS AND METHODS Lumbar spine diskograms and prediskogram MR images of 736 patients (2457 disks) were retrospectively reviewed as part of an institutional review board-approved HIPAA-compliant protocol. Each disk was assigned a Modic subtype: type 0, normal; type 1, nonfatty high signal intensity; type 2, fatty; and type 3, sclerosis. Statistical analysis involved use of a 2 x 2 contingency table of diskogram results for each of the subtypes. The subtype sensitivity, specificity, positive predictive value (PPV), negative predictive value, and confidence intervals (CIs) were calculated. Similar analyses of other MR variables (such as disk herniation, high signal intensity zone, and spondylolisthesis) and type 1 signal intensity changes also were performed. RESULTS Type 1 changes (n = 155) had a high PPV (0.81; 95% CI: 0.74, 0.87) for a provocative diskogram. Type 2 changes (n = 126) had a lower PPV (0.64; 95% CI: 0.55, 0.72) for a positive diskogram. Type 3 changes (n = 21) had a PPV (0.57; 95% CI: 0.34, 0.78) that was not significant for a positive diskogram. The PPV of an endplate with a type 1 change (hereafter, type 1 endplate) for a tear in the annulus fibrosis of the disk was also insignificant (0.14; 95% CI: 0.09, 0.20). A similar analysis between a type 1 endplate and the presence of a disk herniation (PPV, 0.26; 95% CI: 0.19, 0.34) and between a type 1 endplate and vertebral body spondylolisthesis (PPV, 0.28; 95% CI: 0.20, 0.35) were significant. CONCLUSION Type 1 signal intensity changes on MR images have a high positive predictive value in the identification of a pain generator.

Head Impact Biomechanics in Women’s College Soccer

INTRODUCTION There are limited nonlaboratory soccer head impact biomechanics data. This is surprising given soccers global popularity. Epidemiological data suggest that female college soccer players are at a greater concussion injury risk than their male counterparts. Therefore, the purposes of our study were to quantify head impact frequency and magnitude during womens soccer practices and games in the National Collegiate Athletic Association and to characterize these data across event type, playing position, year on the team, and segment of game (first and second halves). METHODS Head impact biomechanics were collected from female college soccer players (n = 22; mean ± SD age = 19.1 ± 0.1 yr, height = 168.0 ± 3.5 cm, mass = 63.7 ± 6.0 kg). We employed a helmetless head impact measurement device (X2 Biosystems xPatch) before each competition and practice across a single season. Peak linear and rotational accelerations were categorized based on impact magnitude and subsequently analyzed using appropriate nonparametric analyses. RESULTS Overall, womens college soccer players experience approximately seven impacts per 90 min of game play. The overwhelming majority (~90%) of all head impacts were categorized into our mildest linear acceleration impact classification (10g-20g). Interestingly, a higher percentage of practice impacts in the 20g-40g range compared with games (11% vs 7%) was observed. CONCLUSION Head impact biomechanics studies have provided valuable insights into understanding collision sports and for informing evidence-based rule and policy changes. These have included changing the football kickoff, ice hockey body checking ages, and head-to-head hits in both sports. Given soccers global popularity, and the growing public concern for the potential long-term neurological implications of collision and contact sports, studying soccer has the potential to impact many athletes and the sports medicine professionals caring for them.

Descriptive Characteristics of Concussions in National Football League Games, 2010-2011 to 2013-2014:

Background: Despite a high reported incidence rate of concussion, little is known about the on-field characteristics of injurious head impacts in National Football League (NFL) games. Purpose: To characterize on-field features (location, player position, and time during game) and biomechanical features (anticipation status, closing distance, impact location and type) associated with concussions in NFL games over a 4-season period (2010-2011 to 2013-2014). Study Design: Descriptive epidemiology study. Methods: We analyzed video of a subset of reported, in-game concussions for the 2010-2011 to 2013-2014 seasons. These videos represented a sample of injuries that were diagnosed and reported on the same day and that could be clearly associated with an in-game collision as captured on video. We determined anticipation status, closing distance, impact location on the injured player’s helmet, and impact type (helmet-to-helmet, helmet-to-body, or helmet-to-ground). Associations between these variables were analyzed by use of descriptive statistics and tests of association. Results: A total of 871 diagnosed concussions were reported as occurring during NFL preseason, regular season, and postseason games for the 2010-2011, 2011-2012, 2012-2013, and 2013-2014 seasons. A total of 1324 games were played during this period, giving a concussion incidence rate of 0.658 per game (95% CI, 0.61-0.70). From the video-reviewed subset (n = 429; 49.3%), the majority of injurious impacts occurred with good anticipation (57.3%) and <10 yards of closing distance (59.0%). An association was found between anticipation status and play type ( χ 3 2 = 27.398, P < .001), largely because injuries occurring on pass plays were more likely to be poorly anticipated than injuries during run plays (43.0% vs 21.4%; χ 1 2 = 14.78, P < .001). Kick returns had the greatest proportion of well-anticipated impacts (78%) and the greatest proportion of impacts with ≥10 yards of closing distance (80%). The type of impact was approximately equally divided between helmet-to-helmet, helmet-to-body, and helmet-to-ground types. The impact location was broadly distributed over the helmet of the injured player. Conclusion: In-game concussions in the NFL occurred through a diverse variety of mechanisms, surprisingly tended to be well-anticipated, and, also surprisingly, occurred with <10 yards of closing distance. The impacts causing concussion were broadly distributed over the helmet. More concussions occurred during the second half of game play, but we do not have evidence to explain this finding.

Effects of Career Duration, Concussion History, and Playing Position on White Matter Microstructure and Functional Neural Recruitment in Former College and Professional Football Athletes

Purpose To better understand the relationship between exposure to concussive and subconcussive head impacts, white matter integrity, and functional task-related neural activity in former U.S. football athletes. Materials and Methods Between 2011 and 2013, 61 cognitively unimpaired former collegiate and professional football players (age range, 52-65 years) provided informed consent to participate in this cross-sectional study. Participants were stratified across three crossed factors: career duration, concussion history, and primary playing position. Fractional anisotropy (FA) and blood oxygen level-dependent (BOLD) percent signal change (PSC) were measured with diffusion-weighted and task-related functional magnetic resonance imaging, respectively. Analyses of variance of FA and BOLD PSC were used to determine main or interaction effects of the three factors. Results A significant interaction between career duration and concussion history was observed; former college players with more than three concussions had lower FA in a broadly distributed area of white matter compared with those with zero to one concussion (t29 = 2.774; adjusted P = .037), and the opposite was observed for former professional players (t29 = 3.883; adjusted P = .001). A separate interaction between concussion history and position was observed: Nonspeed players with more than three concussions had lower FA in frontal white matter compared with those with zero to one concussion (t25 = 3.861; adjusted P = .002). Analysis of working memory-task BOLD PSC revealed a similar interaction between concussion history and position (all adjusted P < .004). Overall, former players with lower FA tended to have lower BOLD PSC across three levels of a working memory task. Conclusion Career duration and primary playing position seem to modify the effects of concussion history on white matter structure and neural recruitment. The differences in brain structure and function were observed in the absence of clinical impairment, which suggested that multimodal imaging may provide early markers of onset of traumatic neurodegenerative disease.

Validation of a Self-Monitoring Tool for Use in Exercise Therapy

Aerobic exercise at a subsymptom heart rate has been recommended as therapy for postconcussion syndrome. Assessing adherence with an accurate heart rate‐monitoring instrument is difficult, limiting the proliferation of large‐scale randomized controlled trials.

Delivering Chest Compressions and Ventilations With and Without Men's Lacrosse Equipment

CONTEXT   Current management recommendations for equipment-laden athletes in sudden cardiac arrest regarding whether to remove protective sports equipment before delivering cardiopulmonary resuscitation are unclear. OBJECTIVE   To determine the effect of mens lacrosse equipment on chest compression and ventilation quality on patient simulators. DESIGN   Cross-sectional study. SETTING   Controlled laboratory. PATIENTS OR OTHER PARTICIPANTS   Twenty-six licensed athletic trainers (18 women, 8 men; age = 25 ± 7 years; experience = 2.1 ± 1.6 years). INTERVENTION(S)   In a single 2-hour session, participants were block randomized to 3 equipment conditions for compressions and 6 conditions for ventilations on human patient simulators. MAIN OUTCOME MEASURE(S)   Data for chest compressions (mean compression depth, compression rate, percentage of correctly released compressions, and percentage of optimal compressions) and ventilations (ventilation rate, mean ventilation volume, and percentage of ventilations delivering optimal volume) were analyzed within participants across equipment conditions. RESULTS   Keeping the shoulder pads in place reduced mean compression depth (all P values < .001, effect size = 0.835) and lowered the percentages of both correctly released compressions ( P = .02, effect size = 0.579) and optimal-depth compressions (all P values < .003, effect size = 0.900). For both the bag-valve and pocket masks, keeping the chinstrap in place reduced mean ventilation volume (all P values < .001, effect size = 1.323) and lowered the percentage of optimal-volume ventilations (all P values < .006, effect size = 1.038). Regardless of equipment, using a bag-valve versus a pocket mask increased the ventilation rate (all P values < .003, effect size = 0.575), the percentage of optimal ventilations (all P values < .002, effect size = 0.671), and the mean volume ( P = .002, effect size = 0.598) across all equipment conditions. CONCLUSIONS   For a mens lacrosse athlete who requires cardiopulmonary resuscitation, the shoulder pads should be lifted or removed to deliver chest compressions. The facemask and chinstrap, or the entire helmet, should be removed to deliver ventilations, preferably with a bag-valve mask.