Charles A. Thigpen

The Landing Error Scoring System (LESS) Is a Valid and Reliable Clinical Assessment Tool of Jump-Landing Biomechanics The JUMP-ACL Study

Background Anterior cruciate ligament injuries are common in athletes and have serious sequelae. A valid clinical tool that reliably identifies individuals at an increased risk for ACL injury would be highly useful for screening sports teams, because individuals identified as “high-risk” could then be provided with intensive prevention programs. Hypothesis A clinical screening tool (the Landing Error Scoring System, or LESS) will reliably identify subjects with potentially high-risk biomechanics. Study Design Cohort study (Diagnosis); Level of evidence, 2. Methods A jump-landing-rebound task was used. Off-the-shelf camcorders recorded frontal and sagittal plane views of the subject performing the task. The LESS was scored from replay of this video. Three-dimensional lower extremity kinematics and kinetics were also collected and used as the gold standard against which the validity of the LESS was assessed. Three trials of the jump-landing task were collected for 2691 subjects. Kinematic and kinetic measures were compared across LESS score quartiles using 1-way analysis of variance; LESS quartiles were compared across genders using the chi-square test. The LESS scores from a subset of 50 subjects were rescored to determine intrarater and interrater reliability. Results Subjects with high LESS scores (poor jump-landing technique) displayed significantly different lower extremity kinematics and kinetics compared with subjects with low LESS scores (excellent jump-landing technique). Women had higher (worse) LESS scores than men. Intrarater and interrater reliability of the LESS ranged from good to excellent. Conclusion The LESS is a valid and reliable tool for identifying potentially high-risk movement patterns during a jump-landing task.

Shoulder Range of Motion Measures as Risk Factors for Shoulder and Elbow Injuries in High School Softball and Baseball Players

Background: Range of motion deficits in shoulder external rotation (ER), internal rotation (IR), total rotation range of motion (ER + IR), and horizontal adduction (HA) have been retrospectively associated with overhand athletes’ arm injuries. Hypothesis: The authors expected the incidence of upper extremity injury in high school softball and baseball players with side-to-side shoulder range of motion deficits to be greater than the incidence of upper extremity injury in players with normal shoulder range of motion. Study Design: Cohort study (prognosis); Level of evidence, 2. Methods: High school softball and baseball players (N = 246) participated. Before the start of the season, passive shoulder ER, IR, and HA were assessed at 90° of abduction with the scapula stabilized. Relative risk (RR) was calculated to examine range of motion measure, by categorical criteria, and risk of upper extremity injury. Results: Twenty-seven shoulder and elbow injuries (9 softball, 18 baseball) were observed during the season. The dominant shoulder of all injured players and baseball players displayed a significant decrease in HA (P = .05) and IR (P = .04). The dominant shoulder total rotation of injured baseball players displayed a significant decrease (mean difference = 8.0° ± 0.1°; P = .05) as compared with the dominant shoulder of uninjured baseball players. Players who displayed a decrease of ≥25° of IR in the dominant shoulder were at 4 times greater risk of upper extremity injury compared with players with a <25° decrease in IR, especially for baseball players. While we observed a 1.5 to 2 times increased risk of injury for the 10° to 20° loss in rotational range of motion for the overall sample and baseball, the risk estimates were not statistically significant (P > .05). Conclusion: There are large mean deficits in shoulder IR and HA between injured and noninjured players, but not in ER or total rotation. Passive shoulder IR loss ≥25° as compared bilaterally was predictive of arm injury. Shoulder range of motion deficits differed between sports and appeared more predictive of injury for baseball players.

The effects of an exercise intervention on forward head and rounded shoulder postures in elite swimmers

Objectives To examine the correction of posture, increase in strength and decrease in shoulder pain and dysfunction in varsity swimmers. Design and Setting Randomised clinical trial. Participants Twenty-eight National Collegiate Athletic Association division I varsity swimmers. Measurements Two testing sessions were conducted before and after an 8-week time period. Posture, strength and shoulder pain and function were assessed. Forward head angle was measured using a digital inclinometer, forward head translation was measured using a ruler and total scapular distance was measured with unmarked string. Average and peak values (N) of strength were measured with the hand-held dynamometer. The intervention subjects then participated in an 8-week exercise training programme to correct posture. The procedures were then repeated in the post-test. Results Significant group by time interactions (p<0.05) were found in forward head angle and forward shoulder translation indicating a decrease in forward head angle and forward shoulder translation. Significant main effects for time (p<0.05) were found in strength measures for all muscle groups indicating increased strength for shoulder girdle muscles tested. Conclusions The exercise intervention was successful at decreasing forward head and rounded shoulder postures in elite swimmers. This study supports the theoretical basis for clinical rehabilitation of posture and the shoulder.

Scapular Kinematics During Supraspinatus Rehabilitation Exercise A Comparison of Full-Can Versus Empty-Can Techniques

Background Supraspinatus strengthening is an important component of shoulder rehabilitation. Previous work has determined that the full-can and empty-can exercises elicit the greatest amount of supraspinatus activity. However, scapular kinematics has not been considered when prescribing supraspinatus exercises. Hypothesis Scapular downward rotation, internal rotation, and anterior tipping during the empty-can exercise are increased when compared with the full-can exercise. Study Design Descriptive laboratory study. Methods Twenty participants performed full-can and empty-can exercises while an electromagnetic tracking system was used to collect three-dimensional scapular kinematic data. Scapular angles at 30 °, 60 °, and 90 ° of the ascending and descending phases of humeral elevation were compared using 2-way repeated measures analysis of variance. Results There was more scapular anterior tipping and internal rotation during the empty-can exercise at all sampled humeral elevation angles except at 30 ° of the descending phase for anterior/posterior tipping (P< .05). Conclusion Scapular anterior tipping and internal rotation are increased during the empty-can exercise, whereas scapular upward rotation was not different between exercises. Clinical Relevance Increased scapular internal rotation and anterior tipping decrease the volume of the supraspinatus outlet during the empty-can exercise. When maintenance of the subacromial space is important, use of the full-can exercise seems most appropriate for selective strengthening of the supraspinatus muscle.

Shoulder Range of Motion Deficits in Baseball Players With an Ulnar Collateral Ligament Tear

Background: Shoulder range of motion (ROM) deficits are associated with elbow injury in baseball players. Purpose: To compare the ROM characteristics of baseball players with a diagnosed ulnar collateral ligament (UCL) tear with those of a group of age-, activity-, and position-matched healthy controls. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Sixty male competitive high school and collegiate baseball players participated. Thirty athletes (age [mean ± standard deviation], 18.20 ± 1.56 years) with a diagnosed UCL tear were compared with 30 (age, 18.57 ± 0.86 years) age-, activity-, and position-matched players without a UCL injury. Of the 60 participants, there were 44 pitchers, 4 catchers, 5 infielders, and 7 outfielders. Participants were measured for shoulder internal rotation (IR), external rotation (ER), and horizontal adduction (HA) at 90° of shoulder elevation. Participants were also measured for elbow extension in a seated position. Group comparisons were made between participants with and without a UCL injury using independent t tests with an α level set at P < .05. All measurements were taken bilaterally, and the differences (involved to uninvolved) were used to calculate means for all variables, including glenohumeral internal rotation deficit (GIRD), total rotational motion (TRM), HA, and elbow extension. Results: Baseball players with a UCL tear (UCLInj) exhibited significantly greater deficits in TRM compared with the control group of healthy baseball players (NUCLInj) (UCLInj = −6.67° ± 11.82°, NUCLInj = 0.93° ± 9.91°; P = .009). No group differences were present for GIRD (UCLInj = −12.53° ± 5.98°, NUCLInj = −13.63° ± 5.90°; P = .476), HA (UCLInj = −3.00° ± 5.01°, NUCLInj = −3.23° ± 5.15°; P = .860), or elbow extension (UCLInj = −2.63° ± 7.86°, NUCLInj = −1.17° ± 2.76°; P = .339). Pitchers with a UCL tear had significantly greater deficits in TRM (UCLInjPitch = −6.96° ± 11.20°, NUCLInjPitch = 1.29° ± 8.33°; P = .0087) and dominant shoulder ER (UCLInjPitch = 112.04° ± 14.35°, NUCLInjPitch = 121.85° ± 9.46°; P = .011) than pitchers without a UCL tear. Conclusion: A deficit in TRM is associated with a UCL tear in baseball players. Although GIRD may be prevalent in throwers, it may not be associated with a UCL injury. When examining ROM in baseball players, it is important to assess both TRM and GIRD.

Changes in passive range of motion and development of glenohumeral internal rotation deficit (GIRD) in the professional pitching shoulder between spring training in two consecutive years

BACKGROUND Pitching causes increased mechanical stress to the arm and is thought to result in alterations in range of motion (ROM) as a result of osseous and soft tissue adaptations. Understanding the factors that contribute to alterations in ROM will allow for improved understanding of the pitching shoulder. This study examined humeral torsion (HT) and shoulder mobility over 2 consecutive years. METHODS Bilateral shoulder mobility and HT were assessed in 33 asymptomatic professional pitchers over 2 spring trainings. A repeated-measures analysis of covariance was used to assess the change in motion of the dominant side/nondominant side across seasons while quantifying pre-existing HT. Prevalence of glenohumeral internal rotation deficit (GIRD) between seasons was compared with χ(2) analysis, and GIRD and non-GIRD pitchers were compared with the independent t test. RESULTS The dominant shoulder displayed increased external rotation (11.5° ± 0.1°, P = .02) and decreased internal rotation (-8.4° ± 11.0°, P = .03) and horizontal adduction (-17.6° ± 13.8°, P = .01). The nondominant shoulder remained the same. Mean HT was significantly different (P = .001) in the dominant (10° ± 11°) arm than in the nondominant arm (23° ± 11°). A significant number of pitchers had with GIRD (P < .01) at each assessment. CONCLUSIONS ROM was significantly altered between seasons of pitching. These changes likely resulted from soft tissue adaptations because we accounted for humeral retrotorsion. Pitchers who developed GIRD displayed a 7° increase in retrotorsion on the dominant shoulder. Changes in the pitching shoulder over time accounting for humeral retrotorsion may suggest pitching ROM is transient and should be monitored.

Bony Adaptation of the Proximal Humerus and Glenoid Correlate Within the Throwing Shoulder of Professional Baseball Pitchers

Background: Elite throwing athletes have increased proximal humeral retrotorsion (HRT) and glenoid retroversion (GRV) in their throwing shoulders compared with their nonthrowing shoulders. These adaptive morphologic changes are thought to be independently protective against shoulder injury; however, their relationship to each other is poorly understood. Purpose: To determine if an association exists between HRT and GRV within the same shoulders of professional pitchers. Study Design: Cross-sectional study; Level of evidence, 3. Methods: The HRT and GRV measurements were determined using published techniques in asymptomatic bilateral shoulders of 32 professional pitchers (mean age, 23 years). Three measurements for each variable were averaged, and the reliability of the techniques was verified. The relationship between HRT and GRV within the same shoulders was determined with Pearson correlation coefficients. Paired t tests were used to compare HRT and GRV between the throwing and nonthrowing shoulder. Simple ratios were calculated between HRT and GRV. Results: Humeral retrotorsion and GRV were both significantly greater on the throwing side compared with the nonthrowing side (HRT: throwing = 9.0° ± 11.4° and nonthrowing = 22.1° ± 10.7°, P < .001; GRV: throwing = 8.6° ± 6.0° and nonthrowing = 4.9° ± 4.8°, P = .001). Within the same shoulders, there was a statistically significant positive association between HRT and GRV on the throwing side (r = 0.43, P = .016) but not on the nonthrowing side (r = −0.13, P = .50). The HRT:GRV ratio was 2.3:1 for throwing shoulders and 7:1 for nonthrowing shoulders. Conclusion: The concurrent increases in dominant shoulder HRT and GRV were observed as a 2:1 “thrower’s ratio.” As this relationship was not observed on the nondominant shoulder, it suggests that bony adaptation of the proximal humerus and glenoid are coupled during skeletal development in the throwing shoulder. Longitudinal studies are needed to confirm this hypothesis.

Shoulder External Rotation Fatigue and Scapular Muscle Activation and Kinematics in Overhead Athletes

CONTEXT Glenohumeral external rotation (GH ER) muscle fatigue might contribute to shoulder injuries in overhead athletes. Few researchers have examined the effect of such fatigue on scapular kinematics and muscle activation during a functional movement pattern. OBJECTIVE To examine the effects of GH ER muscle fatigue on upper trapezius, lower trapezius, serratus anterior, and infraspinatus muscle activation and to examine scapular kinematics during a diagonal movement task in overhead athletes. SETTING Human performance research laboratory. DESIGN Descriptive laboratory study. PATIENTS OR OTHER PARTICIPANTS Our study included 25 overhead athletes (15 men, 10 women; age = 20 ± 2 years, height = 180 ± 11 cm, mass = 80 ± 11 kg) without a history of shoulder pain on the dominant side. INTERVENTION(S) We tested the healthy, dominant shoulder through a diagonal movement task before and after a fatiguing exercise involving low-resistance, high-repetition, prone GH ER from 0° to 75° with the shoulder in 90° of abduction. MAIN OUTCOME MEASURE(S) Surface electromyography was used to measure muscle activity for the upper trapezius, lower trapezius, serratus anterior, and infraspinatus. An electromyographic motion analysis system was used to assess 3-dimensional scapular kinematics. Repeated-measures analyses of variance (phase × condition) were used to test for differences. RESULTS We found a decrease in ascending-phase and descending-phase lower trapezius activity (F(1,25) = 5.098, P = .03) and an increase in descending-phase infraspinatus activity (F(1,25) = 5.534, P = .03) after the fatigue protocol. We also found an increase in scapular upward rotation (F(1,24) = 3.7, P = .04) postfatigue. CONCLUSIONS The GH ER muscle fatigue protocol used in this study caused decreased lower trapezius and increased infraspinatus activation concurrent with increased scapular upward rotation range of motion during the functional task. This highlights the interdependence of scapular and glenohumeral force couples. Fatigue-induced alterations in the lower trapezius might predispose the infraspinatus to injury through chronically increased activation.

The repeatability of scapular rotations across three planes of humeral elevation

Measurement of scapular kinematics is an important component in the assessment of shoulder function; however, repeatability of these measurements has not been established. The purpose of this study, therefore, was to determine the repeatability of scapular rotation measures for different humeral elevation planes between trials, sessions, and days. Three-dimensional scapular rotations were collected using an electromagnetic tracking system in three planes of humeral elevation. Coefficient of multiple correlation (CMC) values were calculated between trials, sessions, and days for curves of scapular rotations. CMC values were compared with repeated measures analysis of variance (ANOVAs) and Tukeys post-hoc procedures. Tests of simple main effects were performed for significant interaction effects. Our results suggest that scapular rotation measures are repeatable between trials within the same testing session, but less repeatable between testing sessions and days. Sagittal plane elevation consistently yielded the highest CMC values for all scapular rotations. These results suggest sagittal plane elevation should be considered to evaluate differences in scapular rotations.

Professional Pitchers With Glenohumeral Internal Rotation Deficit (GIRD) Display Greater Humeral Retrotorsion Than Pitchers Without GIRD

Background: Dominant shoulder glenohumeral internal rotation deficit (GIRD) has been associated with pitching arm injuries. The relationship of humeral torsion on development of GIRD is not clear. Hypothesis: Pitchers displaying GIRD will display greater humeral retrotorsion when compared with those without GIRD. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Humeral torsion and shoulder range of motion (ROM) were measured in 222 professional pitchers before spring training from 2009 to 2012. Shoulder external rotation (ER) and internal rotation (IR) ROM were assessed in 90° of abduction with the scapula stabilized. Humeral torsion was measured via ultrasound using previously described and validated methods. Side-to-side differences in total arc of motion (ER + IR), ER, and IR ROM and humeral torsion were calculated as nondominant minus dominant arm measures for analysis. Pitchers were classified as having GIRD if their dominant arm displayed an IR deficit ≥15° concomitant with a total arc of motion deficit ≥10° compared with their nondominant arm. A mixed-model analysis of variance (side × GIRD) was used to compare dominant and nondominant humeral torsion between pitchers with GIRD (n = 60) and those without GIRD (n = 162). Independent t tests were used to compare the side-to-side difference in humeral torsion between pitchers with GIRD and those without GIRD (α = 0.05). Results: Pitchers with GIRD displayed significantly less humeral torsion (ie, greater retrotorsion) in their dominant arm as compared with those without GIRD (GIRD = 4.5° ± 11.8°, no GIRD = 10.4° ± 11.7°; P = .002). Pitchers with GIRD also displayed a greater side-to-side difference in humeral torsion (GIRD = 19.5° ± 11.9°, no GIRD = 12.3° ± 12.4°; P = .001). However, pitchers with GIRD did not display an increase in dominant ER ROM (dominant ER = 131.8° ± 14.3°, nondominant ER 126.6° ± 13.1°) when compared with those without GIRD (dominant ER = 132.0° ± 14.2°, nondominant ER 122.6° ± 13.1°; P = .03). Pitchers with GIRD displayed expected alterations in ROM (IR = 28.8° ± 9.6°, total arc = 160.6° ± 15.4°; P < .01 for both) when compared with those without GIRD (IR = 39.9° ± 9.9°, total arc = 171.2° ± 15.5°). Conclusion: Pitchers with GIRD displayed greater side-to-side differences and dominant humeral retrotorsion as compared with those without GIRD. The greater humeral retrotorsion may place greater stress on the posterior shoulder resulting in ROM deficits. Pitchers with greater humeral retrotorsion appear to be more susceptible to developing ROM deficits associated with injury and may need increased monitoring and customized treatment programs to mitigate their increased injury risk.