Differences in Shoulder Internal Rotation Strength Between Baseball Players With Ulnar Collateral Ligament Reconstruction and Healthy Controls.

BACKGROUND: Studies have indicated decreased shoulder internal rotation (IR) and external rotation (ER) strength in the throwing limb of baseball players after ulnar collateral ligament injury. There is limited evidence on the recovery of shoulder rotation strength after primary ulnar collateral ligament reconstruction (UCLR). HYPOTHESIS: At the time of return to throwing, baseball players who underwent UCLR would demonstrate decreased IR and ER shoulder strength in the throwing arm as compared with healthy baseball players. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: Male competitive high school and collegiate baseball athletes participated in this study. Athletes who underwent UCLR were compared with healthy controls who were matched by age, height, weight, and position. Bilateral isometric shoulder ER and IR strength was measured using a handheld dynamometer for all participants at the time of initial evaluation (UCLR group) and throughout the course of a season (healthy group). Independent t tests were run to calculate mean differences in ER and IR shoulder strength between the groups, with significance set at P < .05. RESULTS: A total of 86 baseball athletes participated in this study (43 UCLR group, 43 healthy group). At the time of return to throwing (mean ± SD, 194 ± 30 days postoperatively), the 2 groups demonstrated no significant differences in nonthrowing arm ER or IR strength (P = .143 and .994, respectively). No significant difference was found between groups for throwing arm ER strength (P = .921); however, the UCLR group demonstrated significantly less throwing arm IR strength than the healthy group (144.2 ± 27.8 vs 157.6 ± 27.1 N; P = .023). CONCLUSION: The results of this study demonstrate that throwing arm rotator cuff strength may not fully recover before the initiation of a return-to-throwing program after UCLR. These data provide a potential framework for clinicians to assist in the management and exercise prescription of the baseball athlete after UCLR and before medical release and the initiation of a return-to-throwing program.

Effect of Younger Starting Pitching Age on Humeral Retrotorsion in Baseball Pitchers With an Ulnar Collateral Ligament Injury.

BACKGROUND: Increased humeral retrotorsion (HRT) has been found to be a risk factor for ulnar collateral ligament (UCL) tears in baseball players. Recent work has demonstrated the age of 11 years as a potential watershed age for HRT development. HYPOTHESIS: In a group of baseball pitchers with UCL injuries, athletes who started pitching before the age of 10 years will demonstrate significantly more dominant limb humeral retrotorsion (DHRT) when compared with a group of baseball pitchers who reported starting pitching at 10 years or older. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: A total of 84 baseball pitchers with a diagnosed UCL injury were divided into 2 groups based upon the age at which participants began pitching: 33 players reporting a starting pitching age of 10 years or older (group 1) were compared with 51 baseball pitchers reporting a starting pitching age under 10 years (group 2). Participants' DHRT and nondominant limb humeral retrotorsion (NDHRT) were measured using diagnostic ultrasound. Independent t tests were run to compare mean group differences of all patient data, starting pitching age, age at time of injury, DHRT, NDHRT, and humeral retrotorsion difference (HRTdiff). RESULTS: There were no significant differences between groups with regard to age at time of injury, height, weight, or playing years' experience. There was a statistically significant difference in the participant-reported starting pitching age. Significant differences between groups were noted for DHRT (group 1: 20.0°± 9.4°, group 2: 14.5°± 10.3°, P = .015) and for NDHRT (group 1: 38.6°± 8.8°, group 2: 32.9°± 9.5°, P = .007). No significant differences between groups were found for HRTdiff (P = .940). CONCLUSION: Baseball pitchers with a UCL injury who reported a starting pitching age younger than 10 years demonstrated significantly greater DHRT and NDHRT when compared with UCL-injured baseball pitchers who reported a starting pitching age at 10 years or later. The results of this study demonstrate that a younger starting pitching age results in increased HRT in players with UCL injuries.

Blood Biomarkers of Sports-Related Concussion in Pediatric Athletes.

OBJECTIVE: To examine changes in blood biomarkers, serum neurofilament light (Nf-L), and plasma tau, as well as the relationship between blood biomarkers and symptom reports, in athletes with a sports-related concussion. DESIGN: Prospective cohort study. SETTING: Private community-based concussion clinic. PARTICIPANTS: Athletes aged 13 to 18 years old with a diagnosed sports-related concussion presenting to a concussion clinic within 7 days of injury and noninjured athletes with no history of concussion aged 13 to 23 years old. ASSESSMENT AND MAIN OUTCOME MEASURES: Injured athletes provided a blood sample at the initial clinical evaluation and again at least 6 months after injury. Noninjured athletes provided a single blood sample. All participants completed symptom reports during each visit. Statistical comparisons of biomarker concentrations and symptom reports were conducted. RESULTS: The mean rank for tau was significantly lower for concussed athletes compared with nonconcussed athletes. In contrast, the mean rank of Nf-L was higher for concussed athletes than for nonconcussed athletes, although the difference was nonsignificant. Plasma tau was significantly lower postinjury compared with 6 months after injury, whereas serum Nf-L was significantly higher postinjury. There was a weak but significant inverse relationship observed between tau and the number of symptoms reported, but no relationship was observed between Nf-L and the number of symptoms reported. CONCLUSIONS: These data indicate that in the days following a sports-related concussion, the blood biomarkers tau and Nf-L display contrasting patterns of change but may not be related to self-reported symptom scores.

BASEBALL PLAYERS DIAGNOSED WITH ULNAR COLLATERAL LIGAMENT TEARS DEMONSTRATE GREATER SIDE TO SIDE DIFFERENCES IN PASSIVE GLENOHUMERAL ABDUCTION RANGE OF MOTION COMPARED TO HEALTHY CONTROLS.

BACKGROUND: Numerous studies have shown that baseball players develop range of motion adaptations in their throwing arm. While some of these shoulder range of motion adaptations can lead to greater throwing velocity, excessive changes in shoulder range of motion can increase the risk of injury to the ulnar collateral ligament (UCL). PURPOSE/HYPOTHESES: The purpose of this study was to compare the passive GH-ABD ROM measures of baseball players with a diagnosed UCL tear (UCL group) to a group of age, activity, and position matched healthy controls (CONT group). The primary hypothesis was that baseball players with an UCL tear would have a greater loss of passive glenohumeral abduction range of motion in their throwing shoulder than healthy controls. A secondary hypothesis was that baseball players with an UCL tear would demonstrate similar glenohumeral abduction range of motion in their non-throwing arm and increased side-to-side glenohumeral abduction differences compared to the healthy cohort. STUDY DESIGN: Retrospective prospective case-control study. RESULTS: The UCL group had significantly greater glenohumeral abduction range of motion on their throwing shoulder (132.5 °±8.3 °) than the CONT group (120.19 °±11.2 °, p = 0.000). Similarly, the UCL group had increased glenohumeral abduction range of motion on their non-throwing shoulder (141.2 °±9.5 °) compared to the CONT group (124.1 °±11.4 °, p = 0.000). Additionally, the UCL group had a greater glenohumeral abduction difference (-8.7 °±8.4 °) than the CONT group (-3.8 °±7.7 °, p = 0.001). CONCLUSION: In contrast to the original hypotheses, high school and collegiate baseball players that sustained an UCL injury presented with greater glenohumeral abduction range of motion in both their throwing and non-throwing shoulders compared to healthy controls. However, the finding of greater side-to-side glenohumeral abduction range of motion deficits in the UCL group when compared to the matched healthy controls confirms the secondary hypothesis. LEVEL OF EVIDENCE: Level 3.

Correlation Among Y-Balance Test-Lower Quarter Composite Scores, Hip Musculoskeletal Characteristics, and Pitching Kinematics in NCAA Division I Baseball Pitchers.

Context: Numerous studies have reported kinematic data on baseball pitchers using three-dimensional (3D) motion analysis, but no studies to date have correlated this data with clinical outcome measures. Objective: To examine the relationship among Y-Balance Test-Lower Quarter (YBT-LQ) composite scores, musculoskeletal characteristics of the hip, and pitching kinematics in National Collegiate Athletic Association (NCAA) Division I baseball pitchers. Design: Cross-sectional. Setting: 3D motion analysis laboratory. Participants: Nineteen healthy male college baseball pitchers. Main Outcome Measures: Internal and external hip passive range of motion, hip abduction strength, YBT-LQ composite scores, and kinematic variables of the pitching motion. Results: Stride length demonstrated a moderate positive correlation with dominant limb YBT-LQ composite score (r = .524, P = .02) and nondominant limb YBT-LQ composite score (r = .550, P = .01), and a weak positive correlation with normalized time to maximal humerus velocity (r = .458, P = .04). Stride length had a moderate negative correlation with normalized time to maximal thorax velocity (r = -.522, P = .02) and dominant hip total rotational motion (TRM; r = -.660, P = .002), and had a strong negative correlation with normalized time from stride foot contact to maximal knee flexion (r = -.722, P < .001). Dominant limb YBT-LQ composite score had a weak negative correlation with hip abduction strength difference (r = -.459, P = .04) and normalized time to maximal thorax velocity (r = -.468, P = .04). Nondominant limb YBT-LQ composite score demonstrated a weak negative correlation with normalized time to maximal thorax velocity (r = -.450, P = .05) and had a moderate negative correlation with dominant hip TRM (r = -.668, P = .001). There were no other significant relationships between the remaining variables. Conclusions: YBT-LQ is a clinical measure that can be used to correlate with hip musculoskeletal characteristics and pitching kinematics in NCAA Division I pitchers.

Energy Absorption Contribution and Strength in Female Athletes at Return to Sport After Anterior Cruciate Ligament Reconstruction: Comparison With Healthy Controls.

BACKGROUND: Female patients are more likely to suffer a second anterior cruciate ligament (ACL) injury after ACL reconstruction (ACLR) and return to sport (RTS) compared with healthy female controls. Few studies have examined the energy absorption contribution (EAC) that could lead to this subsequent injury. HYPOTHESIS: The ACLR group would demonstrate an altered EAC between joints (hip, knee, and ankle) but no difference in quadriceps, hip abduction, or hip external rotation (ER) strength at the time of RTS. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: A total of 34 female participants (ACLR: n = 17; control: n = 17) were enrolled in the study and matched for age and activity level. Jump landing performance for the initial 50 milliseconds of landing of a lateral-vertical jump was assessed using a 10-camera 3-dimensional motion capture system and 2 force plates. Isokinetic quadriceps strength was measured using a Biodex machine, and hip abduction and ER isometric strength were measured using a handheld dynamometer. All values were normalized to the participant's height and weight. A 1-way multivariate analysis of variance was used to assess between-group differences in the EAC at the hip, knee, and ankle. Two 1-way analyses of variance were used to independently examine quadriceps, hip abduction, and hip ER strength between the groups. RESULTS: Significant differences in the EAC were found between the groups for the involved hip (P = .002), uninvolved hip (P = .005), and involved ankle (P = .023). There were no between-group differences in the EAC for the involved or uninvolved knee or the uninvolved ankle. Patients who underwent ACLR demonstrated significantly decreased quadriceps strength on the involved limb (P = .02) and decreased hip ER strength on both the involved (P = .005) and uninvolved limbs (P = .002). No significant strength differences were found between the groups for the uninvolved quadriceps or for involved or uninvolved hip abduction. CONCLUSION: At RTS, patients who underwent ACLR utilized a greater hip EAC bilaterally and a decreased involved ankle EAC during a lateral-vertical jump. Furthermore, quadriceps strength on the involved limb and hip ER strength of bilateral lower extremities remained decreased. This could place greater stress on the ACL graft and ultimately lead to an increased injury risk.

THE RELATIONSHIP BETWEEN PRE-OPERATIVE AND TWELVE-WEEK POST-OPERATIVE Y-BALANCE AND QUADRICEPS STRENGTH IN ATHLETES WITH AN ANTERIOR CRUCIATE LIGAMENT TEAR.

BACKGROUND: Pre-operative quadriceps strength may have a positive influence on post-operative function and outcomes at time of return to sport. Little consideration has been given to quadriceps strength during the early post-operative timeframes. Twelve-week post-operative anterior cruciate ligament reconstruction (ACL-R) is considered a critical time point for progression in the rehabilitation process. There is currently limited research looking at the relationship between clinical measurements pre-operatively and at 12-weeks following ACL-R. PURPOSE/HYPOTHESIS: The primary purpose of this study was to examine the differences between Y-Balance Test Lower Quarter (YBT-LQ) and isokinetic quadriceps strength tested pre-operatively and post-operatively following ACL-R (12-weeks). STUDY DESIGN: Within subject, repeated measures. METHODS: Thirty-nine participants (15.6 ± 1.5 y/o) were diagnosed with an ACL tear and were undergoing rehabilitation to return to a sport requiring cutting and pivoting were included. YBT-LQ and isokinetic quadriceps strength were assessed pre-operatively and at 12-weeks after ACL-R. YBT-LQ composite scores were calculated bilaterally and isokinetic quadriceps strength was tested using the Biodex Multi-Joint Testing and Rehabilitation System. Paired T-tests were used to determine mean group differences between YBT-LQ and isokinetic quadriceps strength scores pre-operatively and at 12-weeks post-operative. A Pearson Correlation was performed to determine relationships between variables at both time points. RESULTS: There was a significant improvement in YBT-LQ composite scores from pre-operative to 12-weeks post-operative on both the involved (Pre-operative: 89.0 ± 7.7; 12-weeks: 94.1 ± 7.1, p<0.001) and uninvolved (Pre-operative: 92.6 ± 6.2; 12-weeks: 97.6 ± 6.8, p<0.001) limbs. Quadriceps strength decreased significantly from pre-operative to 12-weeks on the involved limb (Pre-operative: 82.3 ftlbs ± 38.6; 12-weeks: 67.9 ftlbs±27.4, p<0.01), but no differences were found on the uninvolved limb (Pre-operative: 117.3ftlbs ± 42.0; 12-weeks: 121.7ftlbs ± 41.5, p = 0.226). CONCLUSIONS: Involved limb quadriceps strength decreases from time of pre-operative to 12-weeks following ACL-R. LEVEL OF EVIDENCE: 3.

Sex Differences in Time to Return-to-Play Progression After Sport-Related Concussion.

BACKGROUND: Recently, female sports participation has increased, and there is a tendency for women to experience more symptoms and variable presentation after sport-related concussion (SRC). The purpose of this study was to determine whether sex differences exist in time to begin a return-to-play (RTP) progression after an initial SRC. HYPOTHESIS: After initial SRC, female athletes (11-20 years old) would take longer to begin an RTP progression compared with age-matched male athletes. STUDY DESIGN: Retrospective cohort study. LEVEL OF EVIDENCE: Level 3. METHODS: A total of 579 participants (365 males [mean age, 15.0 ± 1.7 years], 214 females [mean age, 15.2 ± 1.5 years]), including middle school, high school, and collegiate athletes who participated in various sports and experienced an initial SRC were included and underwent retrospective chart review. The following information was collected: sex, age at injury, sport, history of prior concussion, date of injury, and date of initiation of RTP progression. Participants with a history of more than 1 concussion or injury sustained from non-sport-related activity were excluded. RESULTS: Despite American football having the greatest percentage (49.2%) of sport participation, female athletes took significantly longer to start an RTP progression after an initial SRC (29.1 ± 26.3 days) compared with age-matched male athletes (22.7 ± 18.3 days; P = 0.002). CONCLUSION: On average, female athletes took approximately 6 days longer to begin an RTP progression compared with age-matched male athletes. This suggests that sex differences exist between athletes, aged 11 to 20 years, with regard to initiation of an RTP progression after SRC. CLINICAL RELEVANCE: Female athletes may take longer to recover after an SRC, and therefore, may take longer to return to sport. Sex should be considered as part of the clinical decision-making process when determining plan of care for this population.