Relationship between the medial elbow adduction moment during pitching and ulnar collateral ligament appearance during magnetic resonance imaging evaluation

An Analysis of Intrapitch Variation in Joint and Segment Velocities With Throwing Arm Kinetics in High School and Professional Baseball Pitchers

BACKGROUND

Improper sequencing order of maximal joint and segment velocities has been identified as an important predictor for both throwing arm kinetics and ball velocity.

PURPOSE

To investigate the intrapitcher variation of maximal segment velocities and the relationship to throwing arm kinetics and ball velocity in high school (HS) and professional (PRO) pitchers.

STUDY DESIGN

Descriptive laboratory study.

METHODS

HS (n = 59) and PRO (n = 338) pitchers, instructed to throw 8 to 12 fastball pitches, were evaluated with 3-dimensional motion capture (480 Hz). Maximal joint and segment velocities were calculated for each pitch, and the standard deviation of the maxima was calculated per pitcher. These standard deviations were used to classify pitchers as "low variance" or "high variance" for each segmental velocity subgroup, "overall low variance" or "overall high variance" based on cumulative segment velocity variation, or "population," with any pitcher eligible to be included in multiple subcategories. Maximal velocities and throwing arm kinetics were compared among the various subgroups.

RESULTS

The HS low-variance shoulder internal rotation velocity subgroup (4949 ± 642 deg/s) had significantly lower maximal shoulder internal rotation velocity compared with HS population (5774 ± 1057 deg/s) (P < .001); similar findings were observed for PROs (5269 ± 835 vs 5824 ± 1076 deg/s; P < .001), as well as lower shoulder superior force compared with the PRO population (14.8% ± 8.8% vs 17.8% ± 8.8% body weight; P = .001). The PRO low-variance lead knee extension velocity subgroup had significantly lower maximal lead knee extension velocity (216 ± 135 vs 258 ± 125 deg/s; P = .001) and shoulder distractive force (111.5% ± 14.4% vs 115.6% ± 15.9% body weight; P = .003) compared with the PRO population. The PRO overall low-variance subgroup had significantly lower shoulder distractive force (111.8% ± 14.1% vs 119.6% ± 15.5% body weight; P = .008) and elbow anterior force (40.6% ± 5.0% vs 43.6% ± 6.2% body weight; P = .008) compared with the PRO overall high-variance subgroup.

CONCLUSION

HS and PRO pitchers with low variance for joint and segment velocities achieved significantly lower maximal velocities in the subgroup of interest, while preserving ball velocity. PRO pitchers with overall low variance among multiple maximal joint and segment velocities demonstrated decreased shoulder distractive and elbow anterior force.

CLINICAL RELEVANCE

PRO pitchers with low intrapitch variation in maximal joint and segment velocities may be viewed as kinetically conservative throwers. These pitchers with similarly maintained mechanics between pitches may have an increasingly regimented form that preserves kinetic forces about the throwing arm. The opposite may be true for PRO pitchers with increased variability in segmental velocities during their pitching motion, as they showed increased throwing arm kinetics including shoulder distractive and elbow anterior force compared with the overall low-variance group, theoretically increasing their risk of injury.

Wrist Guards/Supports in Gymnastics: Are They Helping or Hurting You?

BACKGROUND

The prevalence of wrist pain among gymnasts ranges from 46% to 79%. To alleviate wrist pain, gymnasts wear wrist guards/supports (WG/S).

PURPOSE

To investigate the effect of WG/S on the wrist joint through joint moment, angles, total joint range of motion (ROM) arc, and ground-reaction force (GRF).

STUDY DESIGN

Controlled laboratory study.

METHODS

A cross-sectional study design was used to investigate 23 female gymnasts (mean ± SD: age, 12.3 ± 1.5 years; height, 143.4 ± 7.6 cm; mass, 37.7 ± 6.6 kg; body mass index, 18.6 ± 2.9) who performed back handsprings (analyzed by first half [phase 1] and second half [phase 2]) with the following 3 conditions: no WG/S, Skids/Ultimate Wrist Supports (S/UWS), and Tiger Paws (TP). Wrist joint moments, angles, total ROM arc, and GRF were examined by the 3 conditions using analysis of variance with Bonferroni correction and effect size (Cohen d).

RESULTS

For mean wrist flexion moment, both S/UWS and TP showed significantly higher values than the no-WG/S condition in landing phase 1 (S/UWS: P = .001, d = 1.30; TP: P = .019, d = 0.87). In angle comparisons in landing phase 1, no WG/S showed greater mean wrist extension angles compared with S/UWS (P = .046; d = 0.80), but no significant differences with TP (P = .096; d = 0.65). Also, in landing phase 1, total ROM arc of the right wrist was greater in the no-WG/S condition compared with S/UWS (P = .018; d = 0.88), but there were no differences with TP (P = .400; d = 0.52).

CONCLUSION

These data show an increased wrist flexion moment using S/UWS and TP compared with the no-WG/S condition in landing phase 1 of back handsprings. Also, increased wrist extension angles and total arc ROM of the right wrist were found in the no-WG/S condition compared with S/UWS, but not with TP in landing phase 1. S/UWS may be helpful to reduce wrist joint angles, specifically wrist extension in landing phase 1, but both S/UWS and TP caused higher wrist flexion joint moment in landing phase 1. There were no differences found in GFG among the three variables.

CLINICAL RELEVANCE

In the first half of the back handspring, wrist guards can limit wrist extension joint angles and total arc ROM; however, an increased wrist flexion moment was found when wrist guards were worn, which may potentially lead to an increased risk of injury. Injury history, especially overuse signs/symptoms, and previous surgery on the wrist joint need to be well considered before the application or use of wrist guards. Also, the amount of time/exposure wearing wrist guards should be carefully controlled in young female gymnasts.

Kinetic and kinematic comparisons in high school pitchers with low and high pitch location consistency

BACKGROUND

Although ball velocity has often been associated with increased kinetics at the upper extremity and risk of injury in youth and adolescent pitchers, it is unclear if the performance metric pitch location consistency has any positive or negative associations with pitching kinetics.

METHODS

High school pitchers (n = 59) pitched 8-12 fastballs using 3D motion capture (480 Hz). Pitchers were divided into high-consistency (HiCon) and low-consistency (LoCon) groups based on the absolute center deviation of each pitcher's pitch to the center of the pitcher's mean pitch location. Ninety-five percent confidence ellipses with major and minor radii were constructed, and kinematics and kinetics were compared between groups.

RESULTS

Compared with LoCon pitchers, HiCon pitchers had decreased lead hip flexion at elbow extension (40° ± 12° vs. 52° ± 13°, respectively, P = .008), and at foot contact, decreased back hip extension (-1° ± 10° vs. -10° ± 13°, respectively, P = .038) and increased back hip internal rotation (9° ± 15° vs. -2° ± 15°, respectively, P = .043). LoCon pitchers achieved maximum lead hip flexion earlier in the pitch (61.3% ± 23.2% vs. 75.8% ± 15.1%, respectively, P = .039). A multiregression model predicted 0.49 of variance in pitch location consistency using kinematic inputs.

DISCUSSSION AND CONCLUSION

Pitchers who differ in pitch location consistency outcomes do not appear to demonstrate physiologically unsafe kinematics. High school pitchers who strive for improved pitch consistency can consider adjusting parameters of hip kinematics during early portions of the pitch.

Pitching Mechanics and the Relationship to Accuracy in Professional Baseball Pitchers

BACKGROUND

Biomechanical predictors of pitching accuracy are underevaluated in baseball research. It is unclear how pitchers with higher accuracy differ in terms of kinematics and upper extremity kinetics.

PURPOSE

To differentiate high- and low-accuracy professional pitchers by full-body kinematic and upper extremity kinetic parameters.

STUDY DESIGN

Descriptive laboratory study.

METHODS

In total, 121 professional baseball pitchers threw 8 to 12 fastballs while assessed with motion-capture technology (480 Hz). Pitchers were divided into high-accuracy (n = 33), moderate-accuracy (n = 52), and low-accuracy (n = 36) groups based on the absolute center deviation of each pitcher's average pitch to the center of the pitching chart by greater or less than 0.5 SD from the mean, respectively. The 95% confidence ellipses with comparisons of major and minor radii and pitching probability density grids were constructed. Analysis of variance was used to compare kinematic and kinetic values between groups.

RESULTS

The absolute center deviation (14.5% ± 6.7% vs 33.5% ± 3.7% grid width; P < .001) was significantly lower in the high-accuracy compared with the low-accuracy group, with no significant difference in ball velocity (38.0 ± 1.7 vs 38.5 ± 2.0 m/s; P = .222). Lead knee flexion at ball release (30.6°± 17.8° vs 40.1°± 16.3°; P = .023) was significantly less for the high-accuracy pitchers. Peak normalized shoulder internal rotation torque (5.5% ± 1.0% vs 4.9% ± 0.7% body weight [BW] × body height [BH]; P = .008), normalized elbow varus torque (5.4% ± 1.0% vs 4.8% ± 0.7% BW × BH; P = .008), and normalized elbow medial force (42.9% ± 7.3% vs 38.6% ± 6.2% BW; P = .024) were significantly greater for the low-accuracy group compared with the high-accuracy group.

CONCLUSION

Professional pitchers with increased accuracy experienced decreased throwing arm kinetics. These pitchers had increased lead knee extension at later stages of the pitch, potentially providing more stable engagement with the ground and transference of kinetic energy to the upper extremities. Professional pitchers can consider increasing lead knee extension at the final stages of the pitch to improve the accuracy of their throws and mitigate elbow varus torque.

CLINICAL RELEVANCE

Increased elbow varus torque, shoulder internal rotation torque, and elbow medial force in less accurate pitchers may contribute to increased injury risk in this group.

Establishing the Role of Elbow Muscles by Evaluating Muscle Activation and Co-contraction Levels at Maximal External Rotation in Fastball Pitching

Background: Baseball pitching is associated with a high prevalence of ulnar collateral ligament injuries, potentially due to the high external valgus load on the medial side of the elbow at the instant of maximal shoulder external rotation (MER). In-vitro studies show that external valgus torque is resisted by the ulnar collateral ligament but could also be compensated by elbow muscles. As the potential active contribution of these muscles in counteracting external valgus load during baseball pitching is unknown, the aim of this study is to determine whether and to what extent the elbow muscles are active at and around MER during a fastball pitch in baseball.

Methods: Eleven uninjured pitchers threw 15 fastball pitches. Surface electromyography of six muscles crossing the elbow were measured at 2000 Hz. Electromyography signals were normalized to maximal activity values. Co-contraction index (CCI) was calculated between two pairs of the flexor and extensor elbow muscles. Confidence intervals were calculated at the instant of MER. Four ranges of muscle activity were considered; 0–20% was considered low; 21–40% moderate; 41–60% high and over 60% as very high. To determine MER, the pitching motion was captured with a highspeed camera at 240 Hz.

Results: The flexor pronator mass, pronator teres, triceps brachii, biceps brachii, extensor supinator mass and anconeus show moderate activity at MER. Considerable variation between participants was found in all muscles. The CCI revealed co-contraction of the two flexor-extensor muscle pairs at MER.

Interpretation: The muscle activation of the flexor and pronator muscles at MER indicates a direct contribution of forearm muscles crossing the medial side of the elbow in counteracting the external valgus load during fastball pitching. The activation of both flexor and extensor muscles indicates an in-direct contributory effect as the combined activity of these muscles counteract opening of the humeroulnar joint space. We believe that active muscular contributions counteracting the elbow valgus torque can be presumed to relieve the ulnar collateral ligament from maximal stress and are thus of importance in injury risk assessment in fastball pitching in baseball.

Intra- versus inter-pitcher comparisons: Associations of ball velocity with throwing-arm kinetics in professional baseball pitchers

BACKGROUND

The association between ball velocity and elbow varus torque has shown differences when evaluated within a single pitcher and within a cohort. The impact of increasing ball velocity on additional throwing-arm kinetics, in particular shoulder distraction forces, with intra- vs. inter-pitcher evaluations has not been evaluated, even though these kinetic measures have been implicated in injury risk. The purpose of this study was to compare intra- vs. inter-pitcher relationships between ball velocity and all major kinetics at the shoulder and elbow in professional pitchers.

METHODS

A total of 323 professional baseball pitchers threw 8-12 fastball pitches while simultaneously being evaluated with 3-dimensional motion-capture technology (480 Hz). A linear regression analysis was performed to evaluate pitch velocity as a predictor of peak kinetic values at the shoulder and elbow among pitchers. A linear mixed model with random intercepts was then created to evaluate ball velocity as a predictor of peak kinetic values when comparing pitches within an individual pitcher.

RESULTS

91 pitchers were included in the analyses. Ball velocity among pitchers had weak correlations with shoulder distraction force (R² = 0.228, P < .001) and elbow distraction force (R² = 0.175, P < .001). Within an individual pitcher, strong correlations (R² > 0.85) were observed for (1) shoulder internal rotation torque (P < .001), (2) shoulder horizontal adduction torque (P = .006), (3) shoulder superior force (P < .001), (4) shoulder anterior force (P < .001), (5) elbow varus torque (P < .001), (6) elbow medial force (P < .001), (7) elbow anterior force (P < .001), (8) elbow flexion torque (P < .001), (9) shoulder distractive force (P < .001), and (10) elbow distractive force (P < .001).

CONCLUSION

Faster pitch velocity is a weak predictor of shoulder and elbow distraction forces experienced among professional pitchers. However, when controlling for an individual pitcher, peak kinetics at the shoulder and elbow can be strongly predicted by ball velocity. Therefore, the assumption that higher peak throwing-arm kinetic values are experienced by pitchers with faster ball velocity is likely an inappropriate assumption among pitchers but may be correct for each player who increases pitch velocity.

The ulnar collateral ligament loading paradox between in-vitro and in-vivo studies on baseball pitching (narrative review)

Ulnar collateral ligament (UCL) weakening or tears occur in 16% of professional baseball pitchers. To prevent players from sustaining a UCL injury, it is important to understand the relationship between the UCL properties and elbow stabilizers with the load on the UCL during pitching. In-vitro studies showed that the ultimate external valgus torque of 34 Nm would rupture the UCL, which is in apparent conflict with the reported peak valgus torques in pitching (40–120 Nm). Assuming both observations are correct, the question rises why ‘only’ 16 out of 100 professional pitchers sustain a UCL rupture. Underestimation of the effect of other structures in in-vivo studies is most likely the explanation of this mismatch because the calculated in-vivo torque also includes possible contributions of functional and structural stabilizers. In-vitro studies show that the flexor-pronator mass has the potential to counteract valgus torque directly, whereas the elbow flexor-extensor muscles combined with the humeroradial joint might have an indirect effect on valgus torque by increasing the joint compression force. Accurate experimental electromyography data and a more detailed (musculoskeletal)mechanical model of the elbow are needed to investigate if and to what extent the structural and functional stabilizers can shield the UCL during pitching.

Induced power analysis of sequential body motion and elbow valgus load during baseball pitching

The flow of mechanical energy of segmental motion during baseball pitching is poorly understood, particularly in relation to the valgus torque at the elbow which is prone to pitching-related injuries. This study employed an induced power analysis to determine the components of muscle and velocity-dependent torques that contribute to the power of throwing arm segments when the elbow is under valgus load during the arm-cocking phase of pitching. The 3D throwing kinematics and kinetics of 10 adult pitchers were included in this analysis. Pitchers threw with a maximum elbow valgus torque of 73 ± 20 N•m. The trunk flexion and rotation components of the velocity-dependent torque were the greatest contributors to the work of the forearm at -0.53 ± 0.22 J/kg and -0.43 ± 0.21 J/kg, respectively. Approximately 86% of the total energy transferred through the elbow by the velocity-dependent torque was due to trunk motion, which appears to drive the power of accelerating the throwing elbow in valgus. These results support the importance of trunk motion as a key component in the development of elbow torque and ball velocity. Therefore, this study has practical implications for baseball pitchers seeking to minimise injury risk while improving performance.

Segmental Power Analysis of Sequential Body Motion and Elbow Valgus Loading During Baseball Pitching: Comparison Between Professional and High School Baseball Players

Background:

Pitching-related elbow injuries remain prevalent across all levels of baseball. Elbow valgus torque has been identified as a modifiable risk factor of injuries to the ulnar collateral ligament in skeletally mature pitchers.

Purpose:

To examine how segmental energy flow (power) influences elbow valgus torque and ball speed in professional versus high school baseball pitchers.

Study Design:

Descriptive laboratory study.

Methods:

A total of 16 professional pitchers (mean age, 21.9 ± 3.6 years) and 15 high school pitchers (mean age, 15.5 ± 1.1 years) participated in marker-based motion analysis of baseball pitching. Ball speed, maximum elbow valgus torque (MEV), temporal parameters, and mechanical power of the trunk, upper arm, and forearm were collected and compared using parametric statistical methods.

Results:

Professional pitchers threw with a higher ball speed (36.3 ± 2.9 m/s) compared with high school pitchers (30.4 ± 3.5 m/s) (P = .001), and MEV was greater in professional pitchers (71.3 ± 20.0 N·m) than in high school pitchers (50.7 ± 14.6 N·m) (P = .003). No significant difference in normalized MEV was found between groups (P = .497). Trunk rotation time, trunk power, and upper arm power combined to predict MEV (r = 0.823, P < .001), while trunk rotation time and trunk power were the only predictors of ball speed (r = 0.731, P < .001). There were significant differences between the professional and high school groups in the timing of maximum pelvis rotation velocity (42.9 ± 9.7% of the pitching cycle [%PC] vs 27.9 ± 23.4 %PC, respectively; P < .025), maximum trunk rotation (33 ± 16 %PC vs 2 ± 23 %PC, respectively; P = .001), and maximum shoulder internal rotation velocity (102.4 ± 8.9 %PC vs 93.0 ± 11.7 %PC, respectively; P = .017).

Conclusion:

The power of trunk motion plays a critical role in the development of elbow valgus torque and ball speed. Professional and high school pitchers do not differ in elbow torque relative to their respective size but appear to adopt different patterns of segmental motion.

Clinical Relevance:

Because trunk rotation supplies the power associated with MEV and ball speed, training methods aimed at core stabilization and flexibility may benefit professional and high school pitchers in reducing the injury risk and improving pitching performance.

Biomechanical Differences Between Japanese and American Professional Baseball Pitchers

Background:

Although baseball injuries are common in both Japan and the United States, the majority of pitching injuries in Japanese players occur at the shoulder, whereas most pitching injuries in American players occur at the elbow. A biomechanical comparison between Japanese and American pitchers may help to identify the different injury mechanisms.

Hypothesis:

Japanese pitchers produce greater shoulder kinetics whereas American pitchers generate greater elbow kinetics. Also, kinematic differences will be found between the 2 groups, including longer stride and greater lead knee flexion for Japanese pitchers.

Study Design:

Descriptive laboratory study.

Methods:

Biomechanical data for 19 Japanese professional baseball pitchers and an age-matched group of 19 American professional baseball pitchers were collected by use of a 3-dimensional, automated, high-speed optical motion capture system. Anthropometric, kinetic, and kinematic data for both groups were compared by use of t tests (P < .05).

Results:

American pitchers were taller and heavier and generated greater ball velocity (38.1 ± 1.6 vs 34.7 ± 1.1 m/s; P < .001) than their Japanese counterparts. Most elbow and shoulder kinetic parameters, including elbow varus torque (99 ± 17 vs 86 ± 17 N·m; P = .018), were greater for American pitchers. However, when normalized by bodyweight and height, shoulder horizontal adduction torque was greater for Japanese pitchers (6.8% ± 1.0% vs 5.8% ± 1.1%; P = .005). Japanese pitchers had longer stride (86% ± 5% vs 82% ± 6% of height; P = .023), greater shoulder abduction at ball release (101° ± 8° vs 94° ± 9°; P = .014), and greater knee flexion after ball release (39° ± 18° vs 28° ± 14°; P = .039). Japanese pitchers also demonstrated greater shoulder internal rotation velocity, elbow flexion, and elbow extension velocity.

Conclusion:

Greater elbow varus torque may predispose American pitchers to greater risk of elbow injury. Japanese pitchers may have increased risk of shoulder injury due to greater normalized horizontal adduction torque and greater abduction angle. Japanese pitchers may be able to reduce their shoulder torque and risk of injury by shortening their stride, reducing their lead knee flexion, and decreasing their throwing arm abduction.

Clinical Relevance:

Understanding anthropometric, kinetic, and kinematic differences between pitchers from the 2 countries may be of value to clinicians and coaches working to maximize performance of the pitchers while minimizing the risk of injury.

Pitching Performance After Ulnar Collateral Ligament Reconstruction at a Single Institution in Major League Baseball Pitchers

BACKGROUND

Ulnar collateral ligament (UCL) reconstruction (UCLR) has shown reliable rates of return to play, with conflicting results on pitching performance after players' return.

PURPOSE

To evaluate Major League Baseball (MLB) pitching performance before and after UCLR performed at a single institution.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

MLB pitchers (minor league players were excluded) who underwent UCLR at our institution between 2002 and 2016 were identified. Player information and return to play were determined including pitching level (MLB vs minor league) and total number of years played after surgery. Pitching performance statistics were evaluated for 3 years before surgery and for 3 years after returning to play including earned run average (ERA), walks plus hits per inning pitched (WHIP), innings pitched, wins above replacement, runs above replacement, and pitch velocity.

RESULTS

A total of 54 MLB pitchers were identified, with 46 primary and 8 revision reconstructions. The mean time to return to play was 13.8 months (primary reconstruction: 13.7 months). The majority returned to play with a 94% return rate (primary reconstruction: 96%), and 80% returned to MLB play (primary reconstruction: 82%). Three primary reconstructions required revision surgery. Pitchers played a mean of 3.2 years in MLB and 4.6 years total after surgery (39% still playing). Pitching workload and performance were maintained or improved after surgery. The preoperative ERA was 4.63 versus 4.13 after returning to play ( P = .268). Fastball velocity ( P = .032), ERA ( P = .003), and WHIP ( P = .001) worsened the first year after surgery and then improved the second year (ERA: 4.63 to 4.06 [ P = .380]; WHIP: 1.35 to 1.32 [ P = .221]; fastball velocity: 91.3 to 91.9 mph [ P = .097]). Compared with a matched control group, pitchers who had UCLR showed improvements or maintained performance after reconstruction including improved ERA ( P = .007), WHIP ( P = .025), and fastball velocity ( P = .006).

CONCLUSION

MLB players experienced a high rate of return to play and previous level of play after UCLR. Pitching workload was maintained after returning to play. Pitching performance initially decreased the first year after returning and then improved or reverted to previous levels after the first year from UCLR.

Technique Selection 'the Coaches Challenge' Influencing Injury Risk During the First Contact Hand of the Round off Skill in Female Gymnastics

The importance of technique selection on elbow injury risk has been identified for the key round off skill in female gymnastics, with a focus on the second contact limb. The aim of this study was to shift the focus to the first contact limb and investigate the biomechanical injury risk during parallel and T-shape round-off (RO) techniques. Seven international-level female gymnasts performed 10 trials of the RO to back-handspring with parallel and T-shape hand positions. Synchronized kinematic (3D motion analysis system; 247 Hz) and kinetic (two force plates; 1235 Hz) data were collected for each trial. The t-test with effect size statistics determined differences between the two techniques. No significant differences were found for vertical, anterior posterior and resultant ground reaction force, elbow joint kinematics and kinetics. Specifically, the results highlighted that change in technique in RO skills did not influence first contact limb elbow joint mechanics and therefore, injury risk. The findings of the present study suggest the injury potential of this skill is focused on the second limb during the parallel technique of this fundamental gymnastic skill.

Magnetic resonance imaging-based classification for ulnar collateral ligament injuries of the elbow

BACKGROUND

Magnetic resonance imaging (MRI) arthrography has been considered the gold standard for imaging ulnar collateral ligament (UCL) injuries. No classification system has been described for UCL tears to help discuss and guide treatment options. We propose that an MRI-based UCL classification system would correlate with valgus laxity and help predict surgical management.

METHODS

The MRIs from 240 patients who underwent UCL reconstruction were reviewed and classified according to a system based on severity and location of the UCL injury. Bilateral elbow valgus stress radiographs were used to compare the amount of valgus laxity associated with each grade of UCL injury. Additional data from the imaging review included intraligamentous calcifications, T-sign presence, and a newly described "vacuum sign."

RESULTS

The amount of valgus stress opening increased with the classification severity as follows: type I, 0.13 mm; type II, 0.20 mm; type III, 0.63 mm; and type IV, 0.76 mm.

CONCLUSIONS

We propose a new classification for UCL injuries based on MRI findings that helps predict valgus laxity, improve communication, and guide treatment for UCL pathology in throwing athletes.

Major League Baseball pitch velocity and pitch type associated with risk of ulnar collateral ligament injury

BACKGROUND

The number of Major League Baseball (MLB) pitchers requiring ulnar collateral ligament (UCL) reconstructions is increasing. Recent literature has attempted to correlate specific stresses placed on the throwing arm to risk for UCL injury, with limited results.

METHODS

Eighty-three MLB pitchers who underwent primary UCL reconstruction were evaluated. Pitching velocity and percent of pitch type thrown (fastball, curve ball, slider, and change-up) were evaluated 2 years before and after surgery. Data were compared with control pitchers matched for age, position, size, innings pitched, and experience.

RESULTS

The evaluation of pitch velocity compared with matched controls found no differences in pre-UCL reconstruction pitch velocities for fastballs (91.5 vs. 91.2 miles per hour [mph], P = .69), curveballs (78.2 vs. 77.9 mph, P = .92), sliders (83.3 vs. 83.5 mph, P = .88), or change-ups (83.9 vs. 83.8 mph, P = .96). When the percentage of pitches thrown was evaluated, UCL reconstructed pitchers pitch significantly more fastballs than controls (46.7% vs. 39.4%, P = .035). This correlated to a 2% increase in risk for UCL injury for every 1% increase in fastballs thrown. Pitching more than 48% fastballs was a significant predictor of UCL injury, because pitchers over this threshold required reconstruction (P = .006).

CONCLUSION

MLB pitchers requiring UCL reconstruction do not pitch at higher velocities than matched controls, and pitch velocity does not appear to be a risk factor for UCL reconstruction. However, MLB pitchers who pitch a high percentage of fastballs may be at increased risk for UCL injury because pitching a higher percent of fastballs appears to be a risk factor for UCL reconstruction.

Correlates With History of Injury in Youth and Adolescent Pitchers

PURPOSE

To determine the factors within pitcher demographic characteristics, pitching history, and pitch kinematics, including velocity, that correlate with a history of pitching-related injury.

METHODS

Demographic and kinematic data were collected on healthy youth and adolescent pitchers aged 9 to 22 years in preseason training during a single preseason using dual orthogonal high-speed video analysis. Pitchers who threw sidearm and those who had transitioned to another position were excluded. Players were asked whether they had ever had a pitching-related shoulder or elbow injury. Multivariate logistic regression analysis was performed on those variables that correlated with a history of injury.

RESULTS

Four hundred twenty pitchers were included, of whom 31% had a history of a pitching-related injury. Participant height (P = .009, R(2) = 0.023), pitching for more than 1 team (P = .019, R(2) = 0.018), and pitch velocity (P = .006, R(2) = 0.194) served as independent correlates of injury status. A model constructed with these 3 variables could correctly predict 77% of injury histories. Within our cohort, the presence of a 10-inch increase in height was associated with an increase in a history of injury by 20% and a 10-mph increase in velocity was associated with an increase in the likelihood of a history of injury by 12%. Playing for more than 1 team increased the likelihood of a history of injury by 22%.

CONCLUSIONS

Pitch velocity, pitcher height, and pitching for more than 1 team correlate with a history of shoulder and elbow injury. Current recommendations regarding breaking pitches may not prevent injury. Pitchers should be cautioned about pitching for more than 1 team. Taller pitchers and high-velocity pitchers may be at risk of injury.

Postoperative restoration of upper extremity motion and neuromuscular control during the overhand pitch: evaluation of tenodesis and repair for superior labral anterior-posterior tears

BACKGROUND

Superior labral anterior-posterior (SLAP) tears are a common cause of shoulder pain and dysfunction in overhand throwers. Treatment outcomes remain unpredictable, with a large percentage of athletes unable to return to sport. There is considerable debate about the optimal treatment between debridement, repair, and tenodesis.

HYPOTHESIS

Labral repair more closely restores neuromuscular control and motion during the overhand pitch than tenodesis of the long head of the biceps.

STUDY DESIGN

Controlled laboratory study.

METHODS

Eighteen pitchers, including 7 uninjured controls, 6 players pitching after SLAP repair, and 5 players pitching after subpectoral biceps tenodesis (BT), underwent simultaneous surface electromyographic measurement at 1500 Hz and motion analysis at 120 Hz with a 14-camera markerless motion analysis system and high-speed video (120 Hz) to confirm accurate motion tracking. Patients had undergone surgery at least 1 year previously and had returned to pitching with a painless shoulder.

RESULTS

No significant differences were observed in the long head of the biceps muscle, short head of the biceps muscle, deltoid, infraspinatus, or latissimus activity between controls, patients after SLAP repair, and patients after BT. The variability from pitch to pitch for each study participant was similar between groups. Based on visual inspection of the activity time plots, BT appeared to more closely restore the normal pattern of muscular activation within the long head of the biceps muscle than did SLAP repair. There were no significant differences between controls and postoperative patients in the majority of pitching kinematics; however, pitchers after SLAP repair showed significantly altered patterns of thoracic rotation (P = .034) compared with controls and were significantly less likely to fall into previously published normal values for lead knee flexion at front foot contact (P = .019).

CONCLUSION

While both BT and SLAP repair can restore physiologic neuromuscular control, pitchers who undergo SLAP repair may exhibit altered patterns of thoracic rotation when compared with controls and pitchers who undergo BT.

CLINICAL RELEVANCE

While both tenodesis and SLAP repair can restore physiologic neuromuscular control, SLAP repair may alter pitching biomechanics.

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.