The overall injury rates for boys' and girls' high school lacrosse were significantly lower than those for collegiate play. Significant differences existed between adolescent boys and girls with respect to injury mechanisms, body parts injured, and player and team activity at the time of injury.

Background: The latest biomechanical studies on some form of internal bracing have shown improved stabilization for anterior cruciate ligament (ACL) repair, but gap formation and load-sharing function have not yet been reported. Hypothesis: Internal bracing of an adjustable ACL repair construct provides improved stabilization with reduced gap formation and higher residual loading on the ACL. Study Design: Controlled laboratory study. Methods: Internally braced ACL repair constructs with single– and double–cinch loop (CL) cortical buttons, a knotless suture anchor, and a single-CL cortical button with adjustable loop fixation (CLS-ALD) were tested (n = 20 each) in a porcine model at 4 different loads (n = 5 each) over 4000 cycles at 0.75 Hz (n = 80 total). The CLS-ALD technique allowed for additional preconditioning (10 cycles at 0.5 Hz). Test results of the isolated internal brace groups served as a baseline for comparison. Lastly, specimens were pulled to failure (50 mm/min) with a cut internal brace. Final loading and gap formation on the ACL repair construct as well as ultimate strength were analyzed. Results: A statistical significance for peak loads over peak elongation was found between the CLS-ALD and all other reinforced groups (analysis of covariance, P < .001). Accordingly, the adjustable repair technique showed improved load-bearing capability with the internal brace compared with all other fixed repair groups and revealed significantly higher loads than the knotted single-CL group. Also, significantly reduced gap formation was found for the CLS-ALD compared with all other groups ( P < .001), with no gap formation up to 150 N with a final gap of 0.85 ± 0.31 mm at 350 N. A significantly higher ultimate failure load (866.2 ± 104.0 N; P < .001) was found for the button-fixed internal brace group compared with all other groups. Conclusion: Internal bracing had a crucial role in improving the stabilization potential of ACL repair at loads occurring during normal daily activity. The added strength of the internal brace allowed for reducing peak loads on the ACL repair construct as well as restricting gap formation to below 3 mm at loads up to 350 N. Clinical Relevance: Improvements in the mechanical characteristics of current ACL repair techniques that enable reduced gap formation and allow for early range of motion and accelerated rehabilitation may strengthen the self-healing response with the formation of stable scar tissue.

Background:Early cocking phase pitching mechanics may affect risk of upper extremity injury requiring surgery in professional baseball players.Purpose:To assess the occurrence of inverted-W arm positioning and early trunk rotation in Major League Baseball (MLB) pitchers and to determine whether this throwing position is associated with upper extremity injury requiring surgery.Study Design:Cross-sectional study; Level of evidence, 3.Methods:For 250 MLB pitchers in the 2010 season, 15 to 20 pitches from the start and end of an outing were reviewed using slow-motion game video for presence of an inverted-W position and early trunk rotation. Previous or current incidence of upper extremity injury requiring surgery for each player was determined using the MLB injury database, minor league injury records, available collegiate data, and publicly available online injury databases. Upper extremity surgery associated with an injury was considered to result from pitching.Results:Consensus between investigators was achieved for 99% of players for inverted-W positioning (248 players) and in 97% of players for early trunk rotation (243 players) for videos reviewed independently. Rate of surgery with and without inverted-W position was 28 of 93 (30%) and 42 of 155 (27%), respectively. Rate of surgery with and without early trunk rotation was 37 of 111 (33%) and 30 of 132 (23%), respectively. Using a Cox proportional hazards model for risk analysis using the measured number of innings pitched at time of surgery as an approximate index of exposure and adjusting for age and fastball speed at time of surgery, early trunk rotation was associated with significantly increased risk of shoulder and/or elbow surgery with hazard ratio estimate of 1.69 (95% CI, 1.02-2.80). Presence of the inverted-W position was not associated with significantly increased risk (hazard ratio, 1.30; 95% CI, 0.79-2.14).Conclusion:The inverted-W throwing position was not associated with significantly greater risk of upper extremity injury requiring surgery in MLB pitchers. Early trunk rotation was associated with significantly elevated risk of injury requiring surgery.

Background: Recently, there has been a resurgence of interest in primary repair of the anterior cruciate ligament (ACL), with fixation techniques evolving. However, to date, there have been no biomechanical studies comparing fixed to adjustable fixation repair techniques. Hypothesis: Adjustable ACL repair provides for improved stabilization compared with fixed techniques with respect to both gap formation and residual load-bearing capability. Study Design: Controlled laboratory study. Methods: A total of 4 different ACL repair techniques (n = 5 per group), including single– and double–cinch loop (CL) cortical button fixation as well as knotless single–suture anchor fixation, were tested using a porcine model. For adjustable single-CL loop fixation, additional preconditioning (10 cycles at 0.5 Hz) was performed. The force after fixation and the actuator displacement to achieve a time-zero preload of 10 N were measured for fixed techniques. Incrementally increasing cycling (1 mm/500 cycles) from 1 to 8 mm was performed for 4000 cycles at 0.75 Hz before pull to failure (50 mm/min). The final residual peak load and gap formation for each test block were analyzed as well as ultimate strength. Results: Knot tying of a single-CL over a button (mean ± SD, 0.66 ± 0.23 mm) and knotless anchor fixation (0.20 ± 0.12 mm) resulted in significant time-zero gaps ( P < .001) and significantly higher overall gap formation at reduced residual loading (analysis of covariance, P < .001) compared with both the double-CL loop and adjustable fixation techniques. The adjustable group showed the highest failure load and stiffness, at 305.7 N and 117.1 N/mm, respectively. The failure load of the knotted single-CL group was significantly reduced compared with all other groups ( P < .001). Conclusion: Adjustable single-CL cortical button fixation with intraoperative preconditioning optimized time-zero ACL tension and led to significantly improved stabilization and reduced gap formation, with the highest ultimate strength. Single-CL loop knot tying over the button and knotless anchor fixation resulted in time-zero gaps to achieve slight tension on the ACL and significantly higher gap formation at reduced load-bearing capability. Clinical Relevance: Although the clinical relevance of gap formation is uncertain, a biomechanical understanding of the stabilization potential of current ACL repair techniques is pertinent to the continued evolution of surgical approaches to enable better clinical outcomes.

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