P. Gunnar Brolinson

Analysis of real-time head accelerations in collegiate football players.

Objective: To measure and analyze head accelerations during American collegiate football practices and games. Methods: A newly developed in-helmet 6-accelerometer system that transmits data via radio frequency to a sideline receiver and laptop computer system was implemented. From the data transfer of these accelerometer traces, the sideline staff has real-time data including the head acceleration, the head injury criteria value, the severity index value, and the impact location. Data are presented for instrumented players for the entire 2003 football season, including practices and games. Setting: American collegiate football. Subjects: Thirty-eight players from Virginia Techs varsity football team. Main Outcome Measurements: Accelerations and pathomechanics of head impacts. Results: A total of 3312 impacts were recorded over 35 practices and 10 games for 38 players. The average peak head acceleration, Gadd Severity Index, and Head Injury Criteria were 32 g ± 25 g, 36 g ± 91 g, and 26 g ± 64 g, respectively. One concussive event was observed with a peak acceleration of 81 g, a 267 Gadd Severity Index, and 200 Head Injury Criteria. Because the concussion was not reported until the day after of the event, a retrospective diagnosis based on his history and clinical evaluation suggested a mild concussion. Conclusions: The primary finding of this study is that the helmet-mounted accelerometer system proved effective at collecting thousands of head impact events and providing contemporaneous head impact parameters that can be integrated with existing clinical evaluation techniques.

Analysis of Linear Head Accelerations From Collegiate Football Impacts

Sports-related concussions result in 300,000 brain injuries in the United States each year. We conducted a study utilizing an in-helmet system that measures and records linear head accelerations to analyze head impacts in collegiate football. The Head Impact Telemetry (HIT) System is an in-helmet system with six spring-mounted accelerometers and an antenna that transmits data via radio frequency to a sideline receiver and laptop computer system. A total of 11,604 head impacts were recorded from the Virginia Tech football team throughout the 2003 and 2004 football seasons during 22 games and 62 practices from a total of 52 players. Although the incidence of injury data are limited, this study presents an extremely large data set from human head impacts that provides valuable insight into the lower limits of head acceleration that cause mild traumatic brain injuries.

Head impact exposure sustained by football players on days of diagnosed concussion

PURPOSE This study compares the frequency and severity of head impacts sustained by football players on days with and without diagnosed concussion and to identify the sensitivity and specificity of single-impact severity measures to diagnosed injury. METHODS One thousand two hundred eight players from eight collegiate football teams and six high school football teams wore instrumented helmets to measure head impacts during all team sessions, of which 95 players were diagnosed with concussion. Eight players sustained two injuries and one sustained three, providing 105 injury cases. Measures of head kinematics (peak linear and rotational acceleration, Gadd severity index, head injury criteria (HIC15), and change in head velocity (Δv)) and the number of head impacts sustained by individual players were compared between days with and without diagnosed concussion. Receiver operating characteristic curves were generated to evaluate the sensitivity and specificity of each kinematic measure to diagnosed concussion using only those impacts that directly preceded diagnosis. RESULTS Players sustained a higher frequency of impacts and impacts with more severe kinematic properties on days of diagnosed concussion than on days without diagnosed concussion. Forty-five injury cases were immediately diagnosed after head impact. For these cases, peak linear acceleration and HIC15 were most sensitive to immediately diagnosed concussion (area under the curve = 0.983). Peak rotational acceleration was less sensitive to diagnosed injury than all other kinematic measures (P = 0.01), which are derived from linear acceleration (peak linear, HIC15, Gadd severity index, and Δv). CONCLUSIONS Players sustained more impacts and impacts of higher severity on days of diagnosed concussion than on days without diagnosed concussion. In addition, of historical measures of impact severity, those associated with peak linear acceleration are the best predictors of immediately diagnosed concussion.

Timing of concussion diagnosis is related to head impact exposure prior to injury

PURPOSE Concussions are commonly undiagnosed in an athletic environment because the postinjury signs and symptoms may be mild, masked by the subject, or unrecognized. This study compares measures of head impact frequency, location, and kinematic response before cases of immediate and delayed concussion diagnosis. METHODS Football players from eight collegiate and six high school teams wore instrumented helmets during play (n = 1208), of which 95 were diagnosed with concussion (105 total cases). Acceleration data recorded by the instrumented helmets were reduced to five kinematic metrics: peak linear and rotational acceleration, Gadd severity index, head injury criterion, and change in head velocity (Δv). In addition, each impact was assigned to one of four general location regions (front, back, side, and top), and the number of impacts sustained before injury was calculated over two periods (1 and 7 days). RESULTS All head kinematic measures associated with injury, except peak rotational acceleration (P = 0.284), were significantly higher for cases of immediate diagnosis than delayed diagnosis (P < 0.05). Players with delayed diagnosis sustained a significantly higher number of head impacts on the day of injury (32.9 ± 24.9, P < 0.001) and within 7 d of injury (69.7 ± 43.3, P = 0.006) than players with immediate diagnosis (16.5 ± 15.1 and 50.2 ± 43.6). Impacts associated with concussion occurred most frequently to the front of the head (46%) followed by the top (25%), side (16%), and back (13%) with the number of impacts by location independent of temporal diagnosis (χ(3) = 4.72, P = 0.19). CONCLUSIONS Concussions diagnosed immediately after an impact event are associated with the highest kinematic measures, whereas those characterized by delayed diagnosis are preceded by a higher number of impacts.

Can helmet design reduce the risk of concussion in football

Of all sports, football accounts for the highest incidence of concussion in the US due to the large number of athletes participating and the nature of the sport. While there is general agreement that concussion incidence can be reduced through rule changes and teaching proper tackling technique, there remains debate as to whether helmet design may also reduce the incidence of concussion. A retrospective analysis was performed of head impact data collected from 1833 collegiate football players who were instrumented with helmet-mounted accelerometer arrays for games and practices. Data were collected between 2005 and 2010 from 8 collegiate football teams: Virginia Tech, University of North Carolina, University of Oklahoma, Dartmouth College, Brown University, University of Minnesota, Indiana University, and University of Illinois. Concussion rates were compared between players wearing Riddell VSR4 and Riddell Revolution helmets while controlling for the head impact exposure of each player. A total of 1,281,444 head impacts were recorded, from which 64 concussions were diagnosed. The relative risk of sustaining a concussion in a Revolution helmet compared with a VSR4 helmet was 46.1% (95% CI 28.1%-75.8%). When controlling for each players exposure to head impact, a significant difference was found between concussion rates for players in VSR4 and Revolution helmets (χ(2) = 4.68, p = 0.0305). This study illustrates that differences in the ability to reduce concussion risk exist between helmet models in football. Although helmet design may never prevent all concussions from occurring in football, evidence illustrates that it can reduce the incidence of this injury.

Biomechanical analysis of football neck collars.

Objective:To determine the load-limiting capabilities of protective neck collars used in football through dynamic impact testing. Design:A 50th-percentile male Hybrid III dummy was used in 48 dynamic impact tests comparing The Cowboy Collar, Bullock Collar, and Kerr Collar. A control and each collar were tested at two velocities (5 m/s and 7 m/s), three impact locations (front, top, and side of the helmet), and two shoulder pad positions (normal and raised). Setting:Research laboratory. Patients:None. Interventions:None. Independent variables were the neck collars, impact velocity, and shoulder pad position. Main Outcome Measurements:In addition to range of motion, upper and lower neck forces and moments were measured. Results:With the top impact location, it was found that the Kerr Collar and Bullock Collar reduced head accelerations and force transmission through the neck. With the front impact location, all the collars reduced lower neck moment. The Kerr Collar was also capable of reducing the lower neck force and upper neck moment. With the side impact location, the Kerr Collar substantially reduced lower neck moment. Conclusions:These reductions in loads correlate with the degree to which each collar restricted the motion of the head and neck. By restricting the range of motion of the neck and redistributing load to the shoulders, neck loads can be effectively lowered.

Effect of prolotherapy on cellular proliferation and collagen deposition in MC3T3-E1 and patellar tendon fibroblast populations

Proliferative therapy, or prolotherapy, is a treatment for damaged connective tissues involving the injection of a solution (proliferant) which causes local cell death and triggers the bodys wound healing cascade. Physicians vary in their use of this technique; it is employed for ligaments but has also been investigated for tissues such as cartilage. Physicians also vary in treatment regiments using different dosses of the proliferant. This study evaluates several proliferant dosages develop an optimal dosage that maximizes cell and collagen regeneration. This study also looks at cell and collagen regeneration in response to proliferant exposure outside of the healing cascade. MC3T3-E1 cells and patellar tendon fibroblasts were exposed to various amounts of the proliferant P2G and monitored over several weeks. The results showed an inverse relationship between proliferant concentration and cell viability and collagen production in MC3T3-E1 cells. Following exposure, cell populations experienced an initial decrease in cell number followed by increased proliferation. Trichrome staining over 4 weeks showed an increase in collagen production after proliferant exposure. However the cell numbers and amounts of collagen from the treated groups never surpassed those of the untreated groups, although collagen production was comparable in fibroblasts. The results of this basic study show that there is an effective proliferant dosage and point to a local response to the proliferant that increases cell proliferation and collagen production separate from the wound healing cascade. This local response may not be adequate for complete healing and assistance from the bodys healing cascade may be required.

Cross training: indices of training stress and performance

Twenty well-trained runners (VO2max 4.6+/-0.5 L x min[-1]) were age and ability matched and assigned to either a cross training (CT) or run only group (RT). All subjects maintained normal running distance and intensity for 6 wk and reported for three additional training sessions per week. These workouts were performed outdoors on a 400-m track or measured road course (RT) or on a bicycle ergometer (CT). The sessions were as follows: (work x rest(-1) ratio = 1): 5 x 5 min at >95% VO2max/peak (Monday), 50-60 min at 70% VO2max/peak (Wednesday), and 3 x 2.5 min at >105% VO2max/peak, plus 6 x 1.25 min at >115% VO2max/peak (Friday). Subjects were tested before (PRE), after 3 wk (MID), and after 6 wk (POST) of intensified training. Blood samples were obtained from RT, CT, and ten controls (CON) at each time point (0600 h). Runners also completed a 10-min submaximal run at the same absolute intensity (velocity to elicit 75% of initial V02max) during which heart rate, RPE, and VO2 were measured. Each runner then completed a simulated 5-km race (time trial) on a treadmill. Total testosterone (TT), free testosterone (FT), cortisol (C), and creatine kinase activity (CK) were determined. Running economy was similar between RT and CT; however, RPE decreased significantly at MID and POST compared with that at PRE (P < 0.05; time effect). There were no significant differences among groups for TT, FT, or CK, but C was significantly lower in CON than in RT and CT. Performance was significantly faster (P < 0.05; time effect) in the 5-km race at MID (1076.1+/-81.4 s) and POST (1068.6+/-83.9) compared with PRE (1096.6+/-79.5) but was not different between CT and RT. In conclusion, RT and CT responded similarly to 6 wk of increased training, and both groups improved 5-km performance to a similar extent.

Current concepts in the evaluation and management of stress fractures

Although new technologies aid in making a rapid diagnosis and help predict clinical course of treatment, the diagnosis of stress fractures remains dependent on a high index of suspicion. Management of stress fractures involves clinical knowledge of those stress fractures that are prone to complication. The identification of predisposing factors to stress injury should be addressed. These include proper nutrition, hormonal balance, and correcting biomechanical deficits and training errors. Comprehensive evaluation and treatment is essential in facilitating recovery from stress fracture. Several new and more aggressive prevention and treatment strategies have been reported. The maintenance of cardiovascular fitness throughout the recovery process remains a key to the fastest return to full participation.

Management of sport-related concussion: A review

OBJECTIVE To systematically review the evidence for rest, treatment, and rehabilitation after sport-related concussion. DATA SOURCES Nine databases including PubMed, Cochrane Central Register of Controlled Trials, Sport Discus, and Web of Science were searched for studies that evaluated the effect of rest separately from the effects of treatment and/or rehabilitation, using words related to concussion, mild traumatic brain injury, rest, treatment outcome, and therapy. STUDY SELECTION Inclusion criteria were published reports (either articles or abstracts) of original peer-reviewed research that investigated sport-related concussions and evaluated the effects of rest or treatment on the symptoms. One investigator performed the searches. From 749 articles evaluating rest and 1175 evaluating treatment, 2 studies met criteria for the effect of rest and 10 abstracts met criteria for treatment. Three further treatment articles were identified by the authors. DATA EXTRACTION Details of study design, samples, type and duration of treatment, outcome measures, and main results, with effect sizes, were extracted. Confidence intervals (CI) were extracted or calculated where possible. Level of evidence was graded (1-5; best to poorest) using Downs and Black criteria to assess study quality. MAIN RESULTS The 3 studies that investigated rest after concussion were all retrospective case series. The studies were too heterogeneous for a clear assessment of the benefits of rest. Other treatments (evaluated by case studies, retrospective case series, or other level 4 or 5 studies) were subcutaneous sumatriptan, hyperbaric oxygen therapy, amantadine, ibuprofen, and various hormonal treatments. Light exercise, or daily exercise after a 2-week baseline period, appeared to encourage return to physical activity in children and adults. The only randomized controlled trial (with blinded assessment) investigated individualized treatment of 31 participants with symptoms from sport-related concussion that persisted for 12 to 30 months. Interventions included manual spinal therapy, physiotherapy, and neuromotor and sensorimotor retraining compared with rest and graduated exercise, for up to 8 weeks. More participants in the intervention group were medically cleared to return to sport within 8 weeks of initiating treatment (risk ratio 10.3; 95% CI, 1.51-69.6). CONCLUSIONS Studies of management of concussion were so poor that conclusions that rest was not helpful or that exercise might be beneficial are premature. Better evidence showed that individualized treatment of long-standing symptoms may allow earlier return to sport than rest and exercise alone.