Elbow Stress Research Articles

The Effect of the Crow Hop on Elbow Stress During an Interval Throwing Program

Background: Postoperative rehabilitation protocols after ulnar collateral ligament (UCL) reconstruction typically involve a structured interval throwing program. In an effort to minimize torque placed on the UCL, athletes are often instructed to throw with a crow hop, even at short throwing distances. However, the effect of the crow hop on medial elbow stress is unknown. Purpose/Hypothesis: The purpose was to determine whether elbow stress differs with and without a crow hop across the throwing distances of a typical interval throwing program. We hypothesized that crow hop throws would generate lower torque on the elbow than standing throws at each distance of the interval throwing program. Study Design: Controlled laboratory study. Methods: Healthy high school and collegiate pitchers and position players were recruited from the surrounding area. Each player was outfitted with a wearable athletic sleeve and device that recorded elbow torque (Newton-meters), arm slot (degrees), arm speed (revolutions per minute), and shoulder rotation (degrees). Ball velocity (miles per hour) was measured using a radar gun. Players were instructed to perform 3 crow hop throws and 3 standing throws at distances of 30, 45, 60, 90, 120, 150, and 180 feet. A repeated measures analysis of variance was used to compare ball velocity, elbow torque, arm slot, arm speed, and shoulder rotation between crow hop and standing throws at each throwing distance. Results: Twenty athletes participated in this study (average age, 17.8 years; range, 15-25 years). The average medial elbow torque increased at each distance for both crow hop and standing throws at distances of 30, 45, 60, and 90 feet (P < .05), after which there were no significant increases in elbow torque (P > .05). The average torque was higher for crow hop throws than standing throws at distances of 30 feet (13.9 N·m vs 12.0 N·m; P = .002), 45 feet (21.8 N·m vs 19.3 N·m; P = .005), and 60 feet (28.0 N·m vs 24.5 N·m; P = .02). Conclusion: Crow hop throws generated greater medial elbow torque than standing throws at distances up to 60 feet; however, there were no differences in elbow torque at distances greater than 60 feet between the 2 throw types. For both crow hop and standing throws, elbow stress increased at each distance interval up to 90 feet before plateauing at distances greater than 90 feet. The crow hop throwing technique does not reduce medial elbow stress during a simulated interval throwing program, and it may actually increase torque at shorter throwing distances. Clinical Relevance: The results of our study indicate that it would be prudent for players to initially perform standing throws at shorter distances and only later be allowed to employ a natural crow hop at greater distances to minimize torque placed on the medial elbow during UCL rehabilitation protocols.

Effects of Mound Versus Flat-Ground Pitching and Distance on Arm Mechanics and Elbow Torque in High School Pitchers.

Background:Although the monitoring of a pitcher’s throwing arm workload has become a hot topic in both research and the pitching world, the impact of mound height and distance still remains unclear.Purpose:To compare the kinetics and kinematics between pitches from a mound and flat ground at 2 different distances.Study Design:Descriptive laboratory study.Methods:A total of 21 healthy high school varsity baseball pitchers (age, 16.2 ± 1.3 years; weight, 73.6 ± 11.0 kg; height, 181.3 ± 6.4 cm) participated in this study. Players were fitted with a motusBASEBALL sensor and sleeve. Each pitcher was instructed to pitch 5 fastballs under 4 conditions: mound at 60.5 ft (regulation distance), flat ground at 60.5 ft, mound at 50.5 ft, and flat ground at 50.5 ft. Linear mixed-effects models were used to account for both intra- and interplayer variability. A multivariable model was used to evaluate the association of mound pitching, flat-ground pitching, and their distances (50.5 ft and 60.5 ft), and their interaction to arm speed, arm slot, arm rotation, elbow varus torque, and ball velocity.Results:There were no statistically significant effects of mound, flat-ground, or distance variation on arm speed or shoulder rotation. Arm slot was significantly higher (+3.0°; P = .02) on pitches from the mound at 60.5 ft compared with 50.5 ft. Elbow varus torque was lower (–1.5 N·m; P = .02) on mound pitches at 60.5 ft compared with 50.5 ft. Pitches thrown from the mound displayed significantly faster ball velocity compared with flat-ground pitches at both distances (P < .01 for both), with pitches at 60.5 ft having higher velocity (+0.7 m/s; P < .01).Conclusion:Contrary to long-standing notions, the study results suggest that pitching from the mound does not significantly increase stress on the elbow compared with flat-ground pitching. Lower elbow varus torque and faster ball velocity at the regulation distance compared with the reduced distance indicate that elbow stress and ball velocity may not correlate perfectly, and radar guns may not be an appropriate surrogate measure of elbow varus torque.Clinical Relevance:A better understanding of the kinetic and kinematic implications of various throwing programs will allow for the designing of programs that are driven by objective data with aims directed toward injury prevention and rehabilitation in baseball pitchers.

The relationship between shoulder range of motion and elbow stress in college pitchers

College pitchers with increased external rotation gain (ERG) produce increased medial elbow torque (elbow stress)whereas those with reduced total rotational range of motion (ROM) have reduced medial elbow torqueduring pitching. Pitchers were recruited from 3 college baseball teams. Players with prior injury or on pitching restrictions because of pain were excluded. Players were evaluated within 2 weeks before their first game of the season. Pitchers completed an intake survey, and shoulder and arm measurements were taken. Pitchers were fitted with a baseball sleeve that included a sensor at the medial elbow. The sensor calculated elbow torque, arm speed, arm slot, and shoulder rotation for each pitch, while a radar gun measured peak ball velocity. After adequate warm-up, pitchers threw 5 fastballs in a standardized manner off the mound at game-speed effort. The primary outcome evaluated the relationship between shoulder ROM and medial elbow torque. Additional outcomes evaluated pitcher characteristics and demographic characteristics in the context of shoulder ROM. Twenty-eight pitchers were included in the preseason analysis. The average age and playing experience were 20.1 years (standard deviation [SD], 1.3 years) and 15.3 years (SD, 1.8 years), respectively, with 2.5 years (SD, 1.2 years) playing at collegiate level. The dominant shoulder showed decreased internal rotation and increased external rotation (ER) relative to the nondominant side (P < .001). The average glenohumeral internal rotation deficitand ERG were 11.3° (SD, 9.87°) and 5.71° (SD, 8.8°), respectively. ERG ≥ 5° was a significant predictor of elbow stress during pitching (47.4 Nm [SD, 0.7 Nm] vs. 45.1 Nm [SD, 0.6 Nm], P = .014). Univariate associations showed that each additional degree of ER resulted in increased elbow torque (β estimate, 0.35± 0.06 Nm; P = .003). Conversely, decreased medial elbow torque was found in pitchers with reduced shoulder ROM (glenohumeral internal rotation deficit ≥ 20°: 43.5 Nm [SD, 1.1 Nm] vs. 46.6 Nm [SD, 0.5 Nm], P = .011; loss of total rotational ROM ≥ 5°: 43.6 Nm [SD, 1.1 Nm] vs. 46.6 Nm [SD, 0.5 Nm], P = .013)and in those with greater arm length (P < .05). College pitchers with increased ER produce greater medial elbow torque during the pitching movement. Each degree of increased ER was found to correlate with increased elbow torque and ball velocity. On the contrary, arm length and reduced shoulder ROM were associated with reduced medial elbow torque. This study suggests that increased ER in pitchers is associated with greater elbow stress during pitching.

The impact of distance and the crow hop on medial elbow stress during an interval throwing program

Objectives:Rehabilitation programs following ulnar collateral ligament reconstruction include an interval throwing program in order to gradually increase stress and prevent excessive elbow valgus loads. These programs often instruct players to use the crow hop, even at short distances, in order to reduce stress on the reconstructed ligament. The purpose of the study was to evaluate the impact of the crow hop on medial elbow stress at various distances of an interval throwing program.Methods:High school and college-aged baseball players were recruited for this study. Players threw at distances of 30, 45, 60, 90, 120, 150, and 180 feet. At each distance, participants made 3 throws while using a crow hop and 3 throws without using a crow hop with the instruction to throw on an arc. A wearable device recorded elbow torque, arm slot, arm speed, and shoulder rotation. Ball velocity was measured using radar gun.Results:A total of 20 players participated in this study. Overall elbow torque at each distance was 12.9, 20.5, 26.3, 31.9, 34.7, 36.1, and 37.1 Nm, respectively. There was no difference in elbow stress for throws with a crow hop compared to throws without a crow hop at any distance of throwing (p > 0.05). There was no difference in elbow torque for throws at 150 feet compared to 120 feet (p = 0.10) or 150 feet compared to 180 feet (p = 0.83); however, there were significant increases in elbow torque between every other throwing distance (p < 0.05).Conclusions:Medial elbow torque significantly increases at greater throwing distances of a standard interval throwing program, although the effect becomes less pronounced at longer distances as players maximize effort. The crow hop does not affect medial elbow torque at any distance of throwing.

The Relationship Between Shoulder Range of Motion and Arm Stress in College Pitchers: A MOTUS Baseball Study

Objectives:Overuse injuries in overhead athletes are becoming more prevalent, with an unclear relationship between shoulder biomechanics and medial elbow symptoms and injury. The purpose of this study was to investigate the relationship of shoulder range of motion to torque across the medial elbow in college pitchers using a validated MOTUS sensor baseball sleeve.Methods:Pitchers were recruited from three local university baseball teams. Exclusion criteria included injury or restricted activity due to pain. They were evaluated in the preseason, within two weeks before their first game of the season. Pitchers completed workload questionnaires and patient reported outcome measurement information system (PROMIS) pain interference (PI), physical function (PF), and upper extremity (UE) surveys. Shoulder range of motion and upper extremity lengths were measured bilaterally. After adequate warm-up, pitchers were fitted with a MOTUS sensor baseball sleeve (Motus Global, Massapequa, NY) and instructed to throw 5 fastballs in a standardized manner off the mound at game-speed effort. The sensor placed at the medial elbow reported elbow torque, arm speed, arm slot, and shoulder rotation for each pitch, while a radar gun measured peak ball velocity. The primary outcome was to evaluate the relationship between shoulder range of motion and increased stress across the medial elbow. Additional outcomes evaluated pitcher characteristics, demographics, and outcome scores. Outcomes were assessed via a multivariable model, which controlled for possible covariates.Results:Twenty-eight pitchers were included in the preseason analysis with an average (SD) age of 20.1 (1.3) years and playing experience of 15.3 (1.8) years, 2.5 (1.2) of those years at collegiate level. The dominant shoulder demonstrated decreased internal rotation (54.5+/-10.6 vs 65.8+/-9.1) and increased external rotation (ER, 94.1+/-10.4 vs 88.4+/-9.2) relative to the non-dominant side (p < 0.001), while total rotational range of motion (TRROM) was significantly decreased in the dominant arm (148.6+/-12.4 vs 154.1+/-10.6, p < 0.001). The average glenohumeral internal rotation deficiency (GIRD) was 11.3 (9.87) and average external rotation gain (ERG) was 5.71 (8.8). External rotation was found to be a predictor of arm stress, with an increase in 0.35 Nm of elbow torque for every degree increase in ER (beta = 0.35+/-0.06, p = 0.003); there was moderate correlation between ER and arm stress (r = .45, P<.001). Pitchers demonstrated significantly greater arm stress with the following shoulder ROM measurements: GIRD < 20 as compared to greater than 20 degrees (46.6 +/- 0.5 versus 43.5 +/- 1.1, P=.011), ERG greater than 5 as compared to < 5 degrees (47.4 +/- 0.7 versus 45.1 +/- 0.6, P=.014), and loss of total rotational ROM less than 5 as compared to > 5 degrees (46.6 +/- 0.5 versus 43.6 +/- 1.1, P=.013). Multivariate analysis demonstrated significant predictors of PROMIS PF and UE scores were arm stress, ERG, and GIRD (p<0.05), while increased PROMIS PI scores were predicted by increased ERG and GIRD (p<0.05).Conclusion:We found medial elbow stress, arm speed, arm slot, and shoulder rotation as measured by the MOTUS baseball sensor sleeve were influenced by rotational adaptations of the pitching shoulder in collegiate throwing athletes prior to their season. Likewise, arm stress and shoulder rotational adaptations were reflected as predictors of PROMIS PF, UE, and PI scores.

The Relationship of Shoulder and Elbow Stresses and Upper Limb Contact Order During a Round-Off Back Handspring.

Despite high injury incidence rates in gymnastics, there is a paucity of data characterizing upper extremity injury causation and biomechanical risk factors. This study investigated contact forces across multiple joints in both upper extremities during a round-off back handspring (ROBHS), a fundamental gymnastics tumbling maneuver. (1) To characterize the three-dimensional (3-D) biomechanics of the sequential, asynchronous contact of each upper extremity with the ground during a ROBHS using 3-D motion capture, and (2) to evaluate potential correlations to upper extremity injury risk. Observational cross-sectional study. Controlled laboratory environment. Fourteen competitive female gymnasts aged 10-21 years (mean age: 16.6 ± 3.1 years) (1) participating on a competitive gymnastics team; (2) capable of successfully completing a ROBHS; and (3) free of reported injury at enrollment. Not applicable. Variables evaluated include joint angle, torque, compression force, ground reaction force (GRF), time to peak GRF, and limb loading rates. Variables were analyzed at the wrist, elbow, and shoulder of both limbs at ground contact. The hypothesis that these dependent variables would differ by ROBHS upper extremity contact order was formulated retrospectively after data collection. The first contact limb experienced significantly greater extension torque at the elbow (first: 48.89 ± 18.01 Nm, second: 22.49 ± 9.19 Nm; P = .014; CI 95% [14.83, 37.97]) and faster time to peak GRF (P < .001, CI 95% [-1.79, -0.99]). The second limb of contact experienced significantly greater abduction torque at the shoulder (P = .007; CI 95% [-21.58,-8.08]) and anterior-posterior GRF at contact (P = .007; CI 95% [-1.06,-0.26]). The biomechanical differences between contact limbs during the ROBHS may lead to different injury risk. Recognition of the stresses at the elbow and shoulder for both limbs also provides new insight for rehabilitation clinicians to consider when guiding patients to return to gymnastics activity after injury.

Flat Ground Throwing Results in Decreased Ball Velocity and Increased Elbow Torque Compared to Mound Throwing

Objectives: The incidence of shoulder and elbow overuse injury continues to rise in youth baseball players. Several throwing programs designed to reduce stress on the elbow have been described, but most are not evidence-based. The aim of this study was to compare the kinetics and kinematics between mound and flat-ground pitching at two different distances with the goal of developing evidenced-based injury prevention and recovery guidelines for youth throwers. Methods: Fifteen healthy, high school varsity-level baseball pitchers (mean age 16.7 ± 0.7 yrs; height 182.2 ± 6.2 cm; weight 76.0 ± 9.4 kg;) participated in the study. Players were fitted with a motusBASEBALLTM sensor and sleeve (Motus Global, Rockville Centre, NY), which has been shown to have good reliability and correlation with in-laboratory measures. Each pitcher was asked to pitch 5 fastballs to a catcher under each of the 4 conditions: mound at 60.5 ft (regulation distance), flat ground at 60.5 ft, mound at 50.5 ft, and flat ground at 50.5 ft. For each pitch, the sensor recorded arm speed, arm slot, shoulder rotation, and elbow varus torque. Ball velocity was tracked with a radar gun (Stalker Radar, Richardson, TX). Linear mixed-effects models were used to account for both within and between-subject variability. A multivariable model was used to evaluate the association of mound pitching (vs flat ground), distance (50.5 vs 60.5 ft), and their interaction on each of the following outcomes: arm speed, arm slot, shoulder rotation, elbow varus torque, and ball velocity. Results: There were no statistically significant effects of mound vs flat ground or distance variation on both arm speed or shoulder rotation. Arm slot was significantly higher on pitches from the mound at 60.5 ft [+4.58 (95% CI: 1.26, 7.90), p=0.007]. Elbow varus torque was significantly lower on throws from the mound [-1.88 (95% CI: -3.56, -0.20), p=0.03] and from a longer distance [-2.21 (95% CI: -3.89, -0.53), p=0.01]. Pitches thrown from the mound were significantly faster compared to flat ground at both distances, with throws at 60.5 ft of greater velocity than at 50.5 ft [+1.03 (95% CI: 0.66, 1.40), p&lt;0.001]. Please see the Table for full results. Conclusion: The findings suggest that throwing from the mound may not be higher risk compared to flat ground, contrary to long-standing notions. The lower elbow varus torque and higher arm slot, which has previously been shown to be associated with reduced stress, from throwing from the mound may even indicate a protective effect. Compared to 50.5 ft, there was lower elbow varus torque and faster ball velocity at the longer distance, indicating that elbow stress and ball velocity may not correlate perfectly, and radar guns may not be an appropriate surrogate measure of elbow varus torque. A better understanding of the kinetic and kinematic implications of various throwing programs will allow for designing programs that are based on objective data to achieve the goal of preventing injuries in young baseball players. [Table: see text]

Modifiable Mechanical Factors Associated with Increased Fastball Velocity

Objectives:The advent of motion and kinematic analysis of athletes during sport-specific activities has shed light on mechanical factors associated with improved athletic performance. This is especially true in baseball, where motion analysis has provided a nuanced understanding of the pitching motion. Previously, information from motion analysis has been used to identify risk factors for injury, such as to the medial elbow. However, there is less information regarding modifiable mechanical factors associated with increased performance that are safe and do not place the athlete at increased risk for injury. Identification of such variables would allow medical professionals to counsel pitchers on safe and effective ways to improve performance without risking injury. The goal of this study was to identify modifiable mechanical factors that were specific to pitchers throwing with above average fastball velocities.Methods:All participants were recruited from NCAA Division I and III collegiate baseball programs and all participants were currently pitching for their teams and had no history of injury in the preceding 6 months. Participants pitched from a 10-inch mound towards a target with a designated strike zone 60 feet 6 inches away. Each participant pitched the pitch types that they felt most comfortable pitching in a game setting, and pitches were thrown in random order to simulate a game setting. Motion data were collected at 250 Hz using a Vicon 512, 12-camera motion capture system (Vicon Motion Systems, Los Angeles, CA) using previously described methods. A single fastball pitch was randomly selected from each participant for analysis. The average ball velocity was used to place participants into either the ‘high velocity group’ (above average fastball velocity) or ‘low velocity group’ (below average ball velocity). A two-tailed unpaired t-test was performed to determine statistical significance of the variables measured during motion analysis to determine which mechanical differences between the two groups were associated with increased fastball velocity.Results:99 pitchers (avg. age 19.9 +/- 1.4) were enrolled in the study. The average velocity was 70.2 miles per hour (range 49.1 - 80.9). There were 57participants in the high velocity group and 42 participants in the low velocity group. Variables that were statistically different between the two study groups are listed in Table 1. A The high fastball velocity group showed decreased glenohumeral coronal angle at ball release (more ‘side arm’), increased anterior thoracic tilt at ball release, increased anterior pelvic tilt at ball release, increased pelvic obliquity at maximum glenohumeral external rotation (pelvis tilting up towards throwing arm), increased hip abduction at lead foot contact, and increased knee flexion at lead foot contact.Conclusion:The results indicated a number of modifiable variables that were significantly different between the two study groups. Using this information pitchers can look to modify their pitching motion to improve their performance as defined as increased fastball velocity. This information also provides a foundation for future work to determine which of these performance variables are also associated with increased medial elbow stresses that could lead to an increased risk of injury. Using this data could then allow coaches to optimize training regiments to focus on improving performance while minimizing risk of injury.Table 1:Variables associated with high velocity pitchers and low velocity pitchers with associated p-values. BR = ball release; MER = maximal glenohumeral external rotation; FC = foot contact.VariableHigh VelocityLow VelocityP ValuePitching Mechanics associated with increased VelocityGlenohumeral Coronal Angle at BR64.7°72.1°0.01A more ‘side arm’ position at BRThoracic Tilt at BR32.3°25.3°<0.0001Thorax leading towards home plate at BRPelvic Tilt at BR43.5°38.0°<0.0001Pelvis leading towards home plate at BRPelvic Obliquity at MER4.8°0.9°<0.0001Pelvis tilting up towards the throwing arm at late cocking phaseLead Hip Coronal Angle at FC37.0°33.8°0.03Increased lead hip abduction at FCLead Knee Sagittal Angle at FC43.6°40.3°0.03Increased lead knee flexion at FC

Baseball Pitchers’ Perceived Effort Does Not Match Actual Measured Effort During a Structured Long-Toss Throwing Program

Background: During rehabilitation throwing programs, baseball players are commonly asked to throw at reduced levels of effort (ie, 50% effort, 75% effort, etc) to moderate stress to healing tissues. It is currently unknown how changes in players’ perceived exertion compares with changes in actual exertion during structured long-toss programs. Purpose: To determine whether decreased effort correlates with decreased throwing metrics, whether metrics decrease proportionally with reductions in perceived effort, and to quantify intrathrower variability. Study Design: Descriptive laboratory study. Methods: Sixty male high school and collegiate baseball pitchers participated in a structured throwing program. A motusBASEBALL sleeve was worn by all players, which measured elbow varus torque, arm velocity, arm slot, and shoulder rotation. Ball velocity was measured with a radar gun. Each pitcher threw 5 throws a distance of 120 ft with 3 efforts: maximum effort, 75% effort, and 50% effort. Throwing metrics were compared among the 3 levels of effort to see if each 25% decrease resulted in proportional decreases in elbow varus torque and ball velocity. Intrathrower variability was determined for each throwing metric at each degree of effort. Results: All throwing metrics decreased as players decreased their perceived effort (P < .001). However, these observed decreases were much smaller in magnitude than the decreases in perceived effort. During the 75% effort throws, elbow varus torque was only reduced to 93% of maximum and velocity dropped to 86% of maximum. Similarly, for the 50% effort throws, elbow varus torque remained 87% of max effort torque, while velocity remained 78% of max. Intrathrower reliability was considered excellent for most metrics (intraclass correlation coefficient, >0.75). Conclusion: For every 25% decrease in perceived effort, elbow varus torque only decreased 7% and velocity only decreased 11%. Thus, when players throw at what they perceive to be reduced effort, their actual throwing metrics do not decrease at the same rate as their perceived exertion. Clinical Relevance: Measured effort decreased with decreasing perceived effort, but these were not proportional. This has significant implications for physical therapists, physicians, trainers, coaches, and athletes to understand and monitor elbow stress during the rehabilitation process.

Stress Fractures of the Elbow in the Throwing Athlete: A Systematic Review.

Background:Stress fractures of the elbow are rare in throwing athletes and present a challenge from both a management and rehabilitation perspective. Although the incidence of stress fractures of the elbow is increasing, there is a lack of data in the literature focused on throwers.Purpose:To evaluate studies regarding the management and outcomes of stress fractures of the elbow in throwing athletes.Study Design:Systematic review; Level of evidence, 4.Methods:A systematic review was conducted by searching the Scopus, PubMed, and Cochrane Library electronic databases to identify studies reporting on the management and outcomes of stress fractures in overhead-throwing athletes. Management data included nonoperative and operative modalities, and outcome data included return to play, encompassing the timing and level of activity. Studies were excluded if the stress fracture of the elbow was not a result of a sport injury attributed to throwing or if the study failed to report whether an athlete returned to play.Results:Fourteen studies met the inclusion criteria and were included in this analysis. There were 52 patients in total (50 male, 2 female) with a mean age of 19.7 years (range, 13-29.1 years). The olecranon was the most common location of the stress fracture (51 patients; 98.1%), followed by the distal humerus (1 patient; 1.9%). The majority of patients (n = 40; 76.9%) were treated operatively. Of the 40 patients who were treated surgically, 14 (35.0%) underwent a period of conservative treatment preoperatively that ultimately failed because of persistent nonunion or continued elbow pain. A total of 50 patients (96.2%) returned to sport either at or above their preinjury level. Of the 2 patients (3.8%) who did not return to sport, 1 did not return because of continued elbow pain postoperatively, and the other was lost to follow-up. Complications occurred in 9 patients (17.3%), all of whom were treated surgically.Conclusion:On the basis of this systematic review, the majority of elbow stress fractures were treated operatively and approximately one-third after a period of failed nonoperative management. The return-to-sport rate was high. Further, higher level studies are needed to optimize management and return-to-sport rates in this population.

Changes in Throwing Arm Mechanics at Increased Throwing Distances During Structured Long-Toss

Background: Elbow injuries among adolescent baseball players have been outpacing those of college and professional players. In attempts to prevent injuries and maximize return-to-play potential following injury, attention has been focused on “return to throw” programs, which include long-toss throws. Because the few studies that were conducted on long-toss throwing focused primarily on college-aged athletes, it is not known what type of load is incurred at the elbow during interval throwing progression among high school baseball players. Purpose: To quantify the change in arm slot, arm speed, shoulder external rotation, and elbow varus torque across increasing throwing distances within a given athlete. Study Design: Descriptive laboratory study. Methods: Ninety-five high school baseball players performed a long-toss protocol while wearing an inertial sensor and sleeve. Each participant was tested for 5 throws at distances of 9 m, 18 m, 27 m, 37 m, and 46 m. Linear mixed-effects models and likelihood ratio tests were used to estimate the within-participant relationship between throw distance and arm slot, arm speed, shoulder external rotation, and elbow varus torque. Results: Arm slot (P < .01), arm speed (P < .01), shoulder external rotation (P < .01), and elbow varus torque (P < .01) were significantly associated with long-toss throw distance. As the throw distance increased, there was an increase in arm speed and shoulder external rotation and a decrease in arm slot for each distance. However, elbow varus torque increased with each distance up to 37 m and then remained the same at 46 m. Conclusion: The use of longer distances for conditioning and rehabilitation may be beneficial in increasing shoulder range of motion and arm speed; however, precaution needs to be taken, as throwing longer distances are accompanied by an increase in arm rotation, arm speed, and elbow torque, with a decrease in arm slot. Clinical Relevance: Return-to-throw programs have been utilized by sports medicine clinicians and coaches to help guide a player during rehabilitation. These programs involve throwing at increased efforts through increased distances with no immediate feedback on elbow stress. This investigation describes arm biomechanical changes during submaximum interval throwing and demonstrates a tool that can be utilized to measure arm stress in real time for clinicians and athletes progressing through an interval throwing program.

Rehabilitation and Return-to-Play Criteria Following Ulnar Collateral Ligament Reconstruction

Elbow injuries in overhead athletes, particularly ulnar collateral ligament (UCL) injuries to baseball pitchers, continue to increase in number. The reasons for these injuries are multifactorial but typically result from a combination of severe and repetitive valgus elbow stress from pitching large volumes and throwing at peak velocities. These factors and the severity of medial elbow injuries to the UCL complex make it critical to employ a proper criteria-based rehabilitation program in combination with a well-structured set of return-to-play criteria. Together, the rehabilitation process and return-to-play program provide a set of guidelines that help ensure a safe and effective process to aid in returning a throwing athlete back to unrestricted competition as efficiently as possible. This article provides the reader with a 4-phased, criteria-based rehabilitation program for the athlete following UCL reconstruction and a structured set of return-to-play guidelines. The return-to-play progression is a 3-step process that assists in advancing an athlete back to unrestricted competition via a performance, practice, and play sequence. This program uses specific criteria and activities to progress a throwing athlete from high-level performance training, to controlled practice participation and then finally back to play. The program uses not only specific steps but also a combination of testing parameters both subjective and objective to guide the return through the entire rehabilitation process from UCL reconstruction surgery back to unrestricted symptom-free throwing.

Reliability and precision of stress sonography of the ulnar collateral ligament.

Musculoskeletal sonography has emerged as an additional diagnostic tool that can be used to assess medial elbow pain and laxity in overhead throwers. It provides a dynamic, rapid, and noninvasive modality in the evaluation of ligamentous structural integrity. Many studies have demonstrated the utility of dynamic sonography for medial elbow and ulnar collateral ligament (UCL) integrity. However, evaluating the reliabilityand precision of these measurements is critical if sonography is ultimately used as a clinical diagnostic tool. The purpose of this study was to evaluate the reliability and precision of stress sonography applied to the medial elbow. We conducted a cross-sectional study during the 2011 baseball off-season. Eighteen National Collegiate Athletic Association Division I pitchers were enrolled, and 36 elbows were studied. Using sonography, the medial elbow was assessed, and measurements of the UCL length and ulnohumeral joint gapping were performed twice under two conditions (unloaded and loaded) and bilaterally. Intraclass correlation coefficients (0.72-0.94) and standard errors of measurements (0.3-0.9 mm) for UCL length and ulnohumeral joint gapping were good to excellent. Mean differences between unloaded and loaded conditions for the dominant arms were 1.3 mm (gapping; P < .001) and 1.4 mm (UCL length; P < .001). Medial elbow stress sonography is a reliable and precise method for detecting changes in ulnohumeral joint gapping and UCL lengthening. Ultimately, this method may provide clinicians valuable information regarding the medial elbow's response to valgus loading and may help guide treatment options.

Finite Element Analysis of Z-Shaped Pipe in the Directly Buried Heat-Supply Pipeline with Large Diameter

In order to improve Z-shaped pipe in the directly buried heat-supply pipeline with large diameter stress calculations, guiding the engineering design when the short arm length is less than two times the elastic arms length. The author used ANSYS software to numerical simulation analysis on Z-shaped pipe in the directly buried heat-supply pipeline of DN800, DN1000, DN1200, when the long arm length of 50 m, 100 m, 150 m, and the short arm length from two times to one times of the elastic arm length. Applying boundary conditions in different models with the short arm length shortens the process to Z-shaped pipe of the elbow stress. For Z-shaped pipe in the directly buried heat-supply pipeline the short arm from two times to one times of the elastic arm length, the elbow’s stress value is the minimum when the short arm length is 1.2 times of the elastic arm length. This article breaks the specification limits on the short arm length, improving the flexibility of directly buried heat-supply pipeline with large diameter, reducing the difficulty of construction, and it’s important for guiding the actual project.

Biomechanical Comparison of the Interval Throwing Progression and Baseball Pitching

Objectives:The interval throwing progression is a hallmark of the rehabilitation program designed for baseball pitchers or position players returning from shoulder or elbow injury. It typically begins with flat-ground throws at a short distance and progressively increases to 180 feet or more. For pitchers, this phase is then followed by throwing off the mound, progressing from partial-effort to full-effort pitches. Theoretically, the progression of throwing phases allows an injured athlete to gradually recover his flexibility, arm strength, and mechanics while moving from less stressful activities to more stressful activities. While this throwing program has been a part of baseball rehabilitation and conditioning for decades, little is known about the biomechanical stresses generated during flat-ground throwing or variable effort pitching off the mound.Methods:Twenty-nine healthy, college baseball pitchers were analyzed using a quantitative motion analysis system. The participants threw from flat ground at distances of 60-ft, 90-ft, 120-ft, and 180-ft, being instructed to throw “hard, on a horizontal line”. The pitchers then threw fastballs from a mound at 3 different efforts: 60% effort, 80% effort, and full-effort. Biomechanical parameters of position, velocity, and kinetic values were recorded. Mean values were calculated for humeral internal rotation torque (HIRT) and elbow valgus load (EVL) for each throw type. This data was then used to compare shoulder and elbow stresses between the various throws. The differences among mean values were analyzed with a repeated-measures analysis of variance (ANOVA). Post hoc paired t tests were performed when the ANOVA revealed a significant difference.Results:Statistically significant differences exist across all mound intensities (60%, 80%, and 100% effort) for nHIRT (p=0.03) and nEVL (p=0.04), as both parameters increased with percentage throwing effort. No statistically significant differences were found across all flat ground distances in either nHIRT or nEVL (p>0.05). No statistically significant difference in peak HIRT or peak EVL were found when comparing full effort pitching to flat ground throws at any distance (p>0.10). The longer flat ground throws at 180 feet did show significantly different kinematics and biomechanical patterns when compared with pitching from the mound, while shorter flat ground throws had patterns similar to those of pitching.Conclusion:Variable effort pitching off the mound demonstrates significantly lower stresses on the shoulder and elbow during partial-effort throws, illustrating the importance of these throws during the recovery and rehabilitation process. Flat ground throwing at distances as short as 60 feet had similar biomechanical stresses on the upper extremity when compared with pitching full-effort from the mound. Despite lower velocity, this similar stress illustrates the mechanical disadvantage of throwing from the flat ground in a stationary position. No increase in shoulder or elbow stress was seen with increasing distances from the flat ground, likely because the pitchers began using a “crow-hop” for the longer distances, facilitating the throw with their lower extremity. The mechanical advantage of throwing from a mound or using the crow-hop may be protective during rehabilitation and training throws, generating lower humeral internal rotational torque, lower elbow valgus load, and more throwing efficiency.

Pitch Velocity Is a Predictor of Medial Elbow Distraction Forces in the Uninjured High School–Aged Baseball Pitcher

Background:Medial elbow injuries are common among baseball pitchers. Easily accessed methods to assess medial elbow stress may be useful in identifying individuals with increased injury risk.Hypothesis:Pitch velocity (PV) is positively associated with higher medial elbow adduction moments.Study Design:Cohort study; Level of evidence, 2.Methods:Participants included 26 uninjured high school pitchers, 15 to 18 years in age. Three-dimensional data and PV were collected as athletes threw 10 fastballs for strikes to a regulation-distance target. Variables of interest were the normalized peak internal elbow adduction moment and peak PV. Linear regression was performed to evaluate the influence of PV on the adduction moment.Results:For the group, mean PV was 71 mph (range, 58-81 mph), and the adduction moment was 0.558 Nm/Ht × mass (range, 0.378-0.723). PV was positively associated with the adduction moment (P < 0.01, R2= 0.373).Conclusions:Talented young pitchers may be more susceptible to elbow injuries as a consequence of a biomechanical coupling between PV and upper extremity joint moments.Clinical Relevance:PV may be measured easily and serve as an indicator of medial elbow stress.

Mechanical behaviour and rupture of normal and pathological human ascending aortic wall

The mechanical properties of aortic wall, both healthy and pathological, are needed in order to develop and improve diagnostic and interventional criteria, and for the development of mechanical models to assess arterial integrity. This study focuses on the mechanical behaviour and rupture conditions of the human ascending aorta and its relationship with age and pathologies. Fresh ascending aortic specimens harvested from 23 healthy donors, 12 patients with bicuspid aortic valve (BAV) and 14 with aneurysm were tensile-tested in vitro under physiological conditions. Tensile strength, stretch at failure and elbow stress were measured. The obtained results showed that age causes a major reduction in the mechanical parameters of healthy ascending aortic tissue, and that no significant differences are found between the mechanical strength of aneurysmal or BAV aortic specimens and the corresponding age-matched control group. The physiological level of the stress in the circumferential direction was also computed to assess the physiological operation range of healthy and diseased ascending aortas. The mean physiological wall stress acting on pathologic aortas was found to be far from rupture, with factors of safety (defined as the ratio of tensile strength to the mean wall stress) larger than six. In contrast, the physiological operation of pathologic vessels lays in the stiff part of the response curve, losing part of its function of damping the pressure waves from the heart.

Classification, Treatment, and Outcome of Osteochondritis Dissecans of the Humeral Capitellum

Indications for the treatment of osteochondritis dissecans of the humeral capitellum have remained unclear. The aims of this study were to analyze the outcomes and to determine the most useful classification for the choice of treatment. The cases of 106 patients with osteochondritis dissecans of the capitellum were studied retrospectively. At the time of the initial presentation, the mean age of the patients was 15.3 years. The capitellar growth plate was open in eighteen patients and closed in eighty-eight. Thirty-six patients were treated nonoperatively. Fifty-five patients underwent fragment removal alone, twelve underwent fragment fixation with a bone graft, and three underwent reconstruction of the articular surface with use of osteochondral plug grafts from the lateral femoral condyle. The mean follow-up period was 7.2 years. The outcomes in terms of pain in the elbow, return to sports, and radiographic findings were analyzed and compared. An osteochondritis dissecans lesion with an open capitellar physis and a good range of elbow motion resulted in a good outcome. Continued elbow stress resulted in the worst outcome in terms of pain and radiographic findings. In patients with a closed capitellar physis, surgery provided significantly better results than elbow rest (p < 0.01). Fragment fixation or reconstruction provided significantly better results than fragment removal alone (p < 0.05). The results of removal alone were dependent on the size of the defect in the capitellum. The outcome in terms of pain was closely associated with sports activity and radiographic findings. We believe that osteochondritis dissecans of the capitellum can be classified as stable or unstable. Stable lesions that healed completely with elbow rest had all of the following findings at the time of the initial presentation: an open capitellar growth plate, localized flattening or radiolucency of the subchondral bone, and good elbow motion. Unstable lesions, for which surgery provided significantly better results, had one of the following findings: a capitellum with a closed growth plate, fragmentation, or restriction of elbow motion of >or=20 degrees . For large unstable lesions, fragment fixation or reconstruction of the articular surface leads to better results than simple excision.

Classification, Treatment, and Outcome of Osteochondritis Dissecans of the Humeral Capitellum

Indications for the treatment of osteochondritis dissecans of the humeral capitellum have remained unclear. The aims of this study were to analyze the outcomes and to determine the most useful classification for the choice of treatment. The cases of 106 patients with osteochondritis dissecans of the capitellum were studied retrospectively. At the time of the initial presentation, the mean age of the patients was 15.3 years. The capitellar growth plate was open in eighteen patients and closed in eighty-eight. Thirty-six patients were treated nonoperatively. Fifty-five patients underwent fragment removal alone, twelve underwent fragment fixation with a bone graft, and three underwent reconstruction of the articular surface with use of osteochondral plug grafts from the lateral femoral condyle. The mean follow-up period was 7.2 years. The outcomes in terms of pain in the elbow, return to sports, and radiographic findings were analyzed and compared. An osteochondritis dissecans lesion with an open capitellar physis and a good range of elbow motion resulted in a good outcome. Continued elbow stress resulted in the worst outcome in terms of pain and radiographic findings. In patients with a closed capitellar physis, surgery provided significantly better results than elbow rest (p < 0.01). Fragment fixation or reconstruction provided significantly better results than fragment removal alone (p < 0.05). The results of removal alone were dependent on the size of the defect in the capitellum. The outcome in terms of pain was closely associated with sports activity and radiographic findings. We believe that osteochondritis dissecans of the capitellum can be classified as stable or unstable. Stable lesions that healed completely with elbow rest had all of the following findings at the time of the initial presentation: an open capitellar growth plate, localized flattening or radiolucency of the subchondral bone, and good elbow motion. Unstable lesions, for which surgery provided significantly better results, had one of the following findings: a capitellum with a closed growth plate, fragmentation, or restriction of elbow motion of > or =20 degrees . For large unstable lesions, fragment fixation or reconstruction of the articular surface leads to better results than simple excision. Prognostic Level II.

Classification, Treatment, and Outcome of Osteochondritis Dissecans of the Humeral Capitellum

Background: Indications for the treatment of osteochondritis dissecans of the humeral capitellum have remained unclear. The aims of this study were to analyze the outcomes and to determine the most useful classification for the choice of treatment. Methods: The cases of 106 patients with osteochondritis dissecans of the capitellum were studied retrospectively. At the time of the initial presentation, the mean age of the patients was 15.3 years. The capitellar growth plate was open in eighteen patients and closed in eighty-eight. Thirty-six patients were treated nonoperatively. Fifty-five patients underwent fragment removal alone, twelve underwent fragment fixation with a bone graft, and three underwent reconstruction of the articular surface with use of osteochondral plug grafts from the lateral femoral condyle. The mean follow-up period was 7.2 years. The outcomes in terms of pain in the elbow, return to sports, and radiographic findings were analyzed and compared. Results: An osteochondritis dissecans lesion with an open capitellar physis and a good range of elbow motion resulted in a good outcome. Continued elbow stress resulted in the worst outcome in terms of pain and radiographic findings. In patients with a closed capitellar physis, surgery provided significantly better results than elbow rest (p < 0.01). Fragment fixation or reconstruction provided significantly better results than fragment removal alone (p < 0.05). The results of removal alone were dependent on the size of the defect in the capitellum. The outcome in terms of pain was closely associated with sports activity and radiographic findings. Conclusions: We believe that osteochondritis dissecans of the capitellum can be classified as stable or unstable. Stable lesions that healed completely with elbow rest had all of the following findings at the time of the initial presentation: an open capitellar growth plate, localized flattening or radiolucency of the subchondral bone, and good elbow motion. Unstable lesions, for which surgery provided significantly better results, had one of the following findings: a capitellum with a closed growth plate, fragmentation, or restriction of elbow motion of ≥20°. For large unstable lesions, fragment fixation or reconstruction of the articular surface leads to better results than simple excision. Level of Evidence: Prognostic Level II. See Instructions to Authors for a complete description of levels of evidence.