Athletic Injury Management Models in Humans: Revisit

Athletic Injury Management Models in Humans: Revisit

Objective: A human injury model has been proposed wherein subjects were hit with a free-flight tennis ball. The research suggested that additional dependent variables were needed to validate the model. It was hypothesized that increasing the speed of the ball would result in an injury that would create decreased knee extension range of motion, measurable swelling, and a color difference. Methods: Subjects were randomly assigned which leg was struck with the tennis ball. On the identified leg a posterior thigh bruise was induced via a tennis ball fired from a tennis ball machine at ~40m/sec from 46cm. Digital photographs were taken of the trauma site immediately before and on days 2, 4, 6, 8, and 10 posttrauma and were analyzed with Photoshop. Average pixel values of cyan, magenta, yellow, black, and luminosity were calculated at each time point. These data, average pixel values from each day minus the initial pixel values, were used to calculate the overall color difference. Second, a diagnostic ultrasound image was taken of the same location. The acquired image was used to quantify the distance between the skin and the fascia, this measurement representing changes resulting from superficial swelling. Lastly, passive knee extension range of motion was measured with a goniometer. Repeated measures ANOVA followed by multiple pairwise comparisons determined whether these measurements differed over the 5 time points. Pearson correlation was used to determine any relationship between outcome measures. Alpha set at P ≤ 0.05. Results: All subjects bruised. No color differences (F4, 48=1.878, P=0.130), swelling (F4, 68=0.056, P=2.388), or differences in range of motion (F4, 68=1.842, P=0.131) were observed. Likewise, not significant correlations were present between color difference, swelling, or range of motion. Conclusion: This model results in a bruise. However, diagnostic ultrasound measurements and extension range of motion did little to further validate the model.