Junior and Collegiate Tennis Players Display Similar Bilateral Asymmetries of Humeral Retroversion.

CONTEXT: Overhead throwing athletes consistently display significant bilateral differences in humeral retroversion (HRV). However, there is limited evidence regarding HRV asymmetries in tennis players despite similarities between the overhead throw and tennis serve. OBJECTIVE: To determine if junior and collegiate tennis players demonstrate bilateral differences in HRV, and whether the magnitude of the side-to-side difference (HRVΔ) was similar across different age groups. DESIGN: Cross-Sectional Study Setting: Field-Based Patients or Other Participants: Thirty-nine healthy tennis players were stratified into three age groups: Younger Juniors (n = 11; age = 14.5 ± 0.5 years), Older Juniors (n = 12; age = 17.1 ± 0.9 years), and Collegiate (n = 16; age = 19.6 ± 1.2 years). MAIN OUTCOME MEASURES: Three-trial means were calculated for HRV for the dominant and nondominant limbs, and HRVΔ was calculated by subtracting the mean of the nondominant side from the dominant side. Paired-sample t-tests were utilized to determine bilateral differences in HRV, while a one-way ANOVA was used to compare HRVΔ between groups. RESULTS: For all three groups, HRV was significantly greater in the dominant arm compared to the nondominant arm (Younger Juniors: dominant = 62.8° ± 9.1° vs nondominant = 56.3° ± 6.8°, P = .039; Older Juniors: dominant = 75.5° ± 11.2° vs nondominant = 68.6° ± 14.2°, P = .043; Collegiate: dominant = 71.7° ± 8.5° vs nondominant = 61.2° ± 6.9°, P = .001). However, no significant differences were detected in HRVΔ when compared across age groups (P = .511). CONCLUSIONS: Consistent with studies involving overhead throwing athletes, tennis players demonstrated significantly greater measures of HRV in the dominant limb. Further, the development of HRV asymmetries appear to have occurred prior to the teenage years as no changes were observed in HRVΔ between age groups.

Shoulder Flexion Torque Is Augmented by a Volitional Abdominal Isometric Contraction.

ABSTRACT: Cacolice, PA, Carcia, CR, and Scibek, JS. Shoulder flexion torque is augmented by a volitional abdominal isometric contraction. J Strength Cond Res 35(4): 920-923, 2021-A stable core provides a solid base to facilitate effective extremity function. It is unclear whether an individual is able to produce a greater amount of upper extremity torque while performing a volitional core contraction when compared with the independent contraction that occurs subconsciously. Therefore, the purpose of this study was to determine whether peak shoulder flexion torque values were different with and without a concurrent volitional core isometric contraction. Thirty healthy, recreationally active college-aged students participated. Surface electromyography from the rectus abdominis (RA) was captured using a telemetry system interfaced with a software acquisition system and personal computer. In a counterbalanced alternating order, subjects completed 3 trials of maximal isometric shoulder flexion at 90° with and without a volitional abdominal contraction. Percent activation of the RA was greater when subjects volitionally contracted their core (15.8 ± 12.7%) compared with the subconscious contracted condition (6.3 ± 4.8%) (p ≤ 0.001). Isometric shoulder flexion peak torque was greater when the core was actively contracted (44.6 ± 18.9 N × m) compared with when the core was recruited subconsciously (30.7 ± 15.7 N × m) (p ≤ 0.001). These findings suggest the clinician should encourage the individual to activate their core musculature when performing upper extremity strength activities.

Ground Reaction Forces Are Predicted with Functional and Clinical Tests in Healthy Collegiate Students.

Increased vertical and posterior ground reaction forces (GRFs) are associated with anterior cruciate ligament (ACL) injury. If a practical means to predict these forces existed, ACL injury risk could be attenuated. Forty-two active college-age individuals (21 females, 20.66 ± 1.46 y, 70.70 ± 2.36 cm, 82.20 ± 7.60 kg; 21 males, 21.57 ± 1.28 y, 65.52 ± 1.87 cm, 64.19 ± 9.05 kg) participated in this controlled laboratory study. GRFs were ascertained by having the subjects perform a unilateral landing task onto a force plate. Several clinical measures (Fat Free Mass (FFM), dorsiflexion passive range of motion (DPROM), isometric peak force of the lateral hip rotators, knee flexor/extensor peak force ratio (H:Q), the completion of the overhead deep squat), two functional tests (Margaria-Kalamen, Single Leg Triple Hop (SLTH)), and sex served as the predictor variables. Regression models to predict the GRFs normalized to the FFM (nGRFz, nGRFy) were generated. nGRFz was best predicted with a linear regression equation that included SLTH and DPROM (adjusted R2 = 0.274; p = 0.001). nGRFy was best predicted with a linear regression equation that included H:Q, FFM, and DPROM (adjusted R2 = 0.476; p < 0.001). Simple clinical measures and functional tests explain a small to moderate amount of the variance associated with the FFM normalized vertical and posterior GRFs in active college-age individuals.

Reliability and Validity of a 1-Person Technique to Measure Humeral Torsion Using Ultrasound.

CONTEXT: Knowledge of the bilateral difference in humeral torsion (HT) enables clinicians to implement appropriate interventions for soft tissue restrictions of the shoulder to restore rotational motion and reduce injury risk. Whereas the current ultrasound method for measuring HT requires 2 assessors, a more efficient 1-person technique (1PT) may be of value. OBJECTIVE: To determine if a 1PT is a reliable and valid alternative to the established 2-person technique (2PT) for indirectly measuring HT using ultrasound. DESIGN: Descriptive laboratory study. SETTING: Biomechanics laboratory. PATIENTS OR OTHER PARTICIPANTS: A convenience sample of 16 volunteers (7 men, 9 women; age = 26.9 ± 6.8 years, height = 172.2 ± 10.7 cm, mass = 80.0 ± 13.3 kg). MAIN OUTCOME MEASURE(S): We collected the HT data using both the 1PT and 2PT from a total of 30 upper extremities (16 left, 14 right). Within-session intrarater reliability (intraclass correlation coefficient; ICC [3,1]) and standard error of measurement (SEM) were assessed for both techniques. Simple linear regression and Bland-Altman analysis were used to examine the validity of the 1PT when compared with the established 2PT. RESULTS: The 1PT (ICC [3,1] = 0.992, SEM = 0.8°) and 2PT (ICC [3,1] = 0.979, SEM = 1.1°) demonstrated excellent within-session intrarater reliability. A strong linear relationship was demonstrated between the HT measurements collected with both techniques ( r = 0.963, r2 = 0.928, F1,28 = 361.753, P < .001). A bias of -1.2° ± 2.6° was revealed, and the 95% limits of agreement indicated the 2 techniques can be expected to vary from -6.3° to 3.8°. CONCLUSIONS: The 1PT for measuring HT using ultrasound was a reliable and valid alternative to the 2PT. By reducing the number of testers involved, the 1PT may provide clinicians with a more efficient and practical means of obtaining these valuable clinical data. a.

STRENGTH PROFILES IN HEALTHY INDIVIDUALS WITH AND WITHOUT SCAPULAR DYSKINESIS.

BACKGROUND: Muscular weakness of the shoulder complex is commonly found in patients presenting with scapular dyskinesis; however, little is known regarding muscular performance in healthy individuals with scapular dyskinesis. PURPOSE: To compare isometric strength measures of the shoulder complex between healthy individuals with and without scapular dyskinesis. It was hypothesized that healthy individuals with scapular dyskinesis would demonstrate decreased isometric strength of the scapular stabilizers and rotator cuff when compared to healthy individuals without scapular dyskinesis. STUDY DESIGN: Cross-sectional study. METHODS: Forty healthy, college-aged participants were recruited. Sixty-eight percent of subjects (27 of 40) presented with scapular dyskinesis. Thus, a matched-pairs analysis was conducted with 26 subjects (age: 22.00 ± 2.06 y; height: 168.77 ± 8.07 cm; mass: 70.98 ± 13.14 kg; BMI: 24.75 ± 3.04 kg/m2; 6 males; 20 females). The presence of scapular dyskinesis was determined visually using the scapular dyskinesis test with a dichotomous outcome (yes/no). Strength of the scapular stabilizers and rotator cuff was assessed via manual muscle testing using a handheld dynamometer. Force measures obtained with the handheld dynamometer were used to quantify strength. For each muscle tested, the mean peak force of three trials were normalized to body weight and used for data analysis. Additionally, strength ratios were calculated and analyzed. Differences in strength and strength ratios between those with and without scapular dyskinesis were compared using separate two-way mixed ANOVAs with repeated measures. RESULTS: No significant differences for either strength (F1.83,43.92 = 1.10, p = .34) or strength ratios (F1.83,44.02 = 1.93, p = .16) were observed between those with and without scapular dyskinesis. A significant main effect (F1.83,43.92 = 239.32, p < .01) for muscles tested was observed, and post-hoc analysis revealed significant trends resulting in a generalized order: the upper trapezius generated the greatest amount of force, followed by serratus anterior and middle trapezius, lower trapezius, supraspinatus, medial rotators, and lateral rotators. CONCLUSION: The results of this study indicate that differences in shoulder muscle strength do not exist between healthy subjects with and without scapular dyskinesis. Additionally, scapular dyskinesis appears to be prevalent in healthy populations. LEVEL OF EVIDENCE: Level 3.

Collecting shoulder kinematics with electromagnetic tracking systems and digital inclinometers: A review.

The shoulder complex presents unique challenges for measuring motion as the scapula, unlike any other bony segment in the body, glides and rotates underneath layers of soft tissue and skin. The ability for clinicians and researchers to collect meaningful kinematic data is dependent on the reliability and validity of the instrumentation utilized. The aim of this study was to review the relevant literature pertaining to the reliability and validity of electromagnetic tracking systems (ETS) and digital inclinometers for assessing shoulder complex motion. Advances in technology have led to the development of biomechanical instrumentation, like ETS, that allow for the collection of three-dimensional kinematic data. The existing evidence has demonstrated that ETS are reliable and valid instruments for collecting static and dynamic kinematic data of the shoulder complex. Similarly, digital inclinometers have become increasingly popular among clinicians due to their cost effectiveness and practical use in the clinical setting. The existing evidence supports the use of digital inclinometers for the collection of shoulder complex kinematics as these instruments have been demonstrated to yield acceptable reliability and validity. While digital inclinometers pose a disadvantage to ETS regarding accuracy, precision, and are limited to two-dimensional and static measurements, this instrument provides clinically meaningful data that allow clinicians and researchers the ability to measure, monitor, and compare shoulder complex kinematics.

THE USE OF FUNCTIONAL TESTS TO PREDICT SAGITTAL PLANE KNEE KINEMATICS IN NCAA-D1 FEMALE ATHLETES.

BACKGROUND: Landing with the knee in extension places increased loads on ligamentous restraints at the knee versus landing in flexion. Unfortunately, existing methods to predict landing kinematics require sophisticated equipment and expertise. The purpose of this study was to develop predictive models for sagittal plane tibiofemoral landing kinematics from the results of functional tests. METHODS: Twenty-nine female, NCAA-D1 college athletes (mean ± standard deviation, age = 19.03 ± 1.09; mass=66.56 ± 13.47 kg; height = 171.16 ± 7.92 cm) participated in a descriptive, laboratory study. Participants performed five unilateral, dominant lower extremity (LE) landings from a 35cm platform onto a forceplate. LE three-dimensional kinematics were captured with electromagnetic sensors interfaced with motion analysis software. Then in a randomized order, participants performed three standardized functional tests: single limb triple hop (SLTH), countermovement vertical jump (CMVJ) and the Margaria-Kalamen (MK) test. Sagittal plane tibiofemoral joint angle at initial contact (IC) and excursion (EXC) in the first 0.1s after ground contact were entered into a statistical software package. Multiple linear regression analyses generated one model predicting IC and one predicting EXC from the independent variables. Alpha levels were set a priori at p ≤ .05. RESULTS: A two variable (MK, SLTH) linear regression model that predicted EXC was significant (Adjusted R (2) = .213, p = .017), however the model that predicted IC was not (p = .890). CONCLUSION: Knee flexion excursion following a single leg landing task may be predicted with the MK and SLTH. The use of functional tests provides a practical means to predict landing kinematics to clinicians working with an active, athletic population. LEVEL OF EVIDENCE: 3, cohort study.

Validation of a new method for assessing scapular anterior-posterior tilt.

BACKGROUND: Electromagnetic tracking systems have enabled some investigators and clinicians to measure tri-planar scapular motion; yet, they are not practical and affordable options for all clinicians. Currently, the ability to affordably quantify scapular motion is limited to monitoring only the motion of scapular upward rotation, with use of a digital inclinometer. HYPOTHESIS/PURPOSE: The objective of this study was to determine the criterion-related validity of a modified digital inclinometer when used to measure the motion of scapular anterior-posterior (AP) tilt. MATERIALS & METHODS: Thirteen volunteers, free from any history of shoulder injury, reported for a single testing session. Each subject underwent a brief shoulder and posture examination in order to confirm the absence of pathology. Subjects actively performed clinically relevant amounts of humeral elevation in the scapular plane while in a seated position. An electromagnetic tracking system (Ascension Technology, Burlington, VT) and a modified inclinometer (Pro 360, Baseline®, Fabrication Enterprises, White Plains, NY) were used to acquire scapular AP tilt over the same shoulder motions. Criterion-related validity was determined using Pearson Product Moment correlations. RESULTS: Correlation analyses revealed significant moderate to good associations (r = 0.63 to 0.86, p < 0.01) between scapular AP tilt measures obtained with a digital inclinometer and an electromagnetic tracking system. CONCLUSIONS: A modified digital inclinometer is a moderately valid device to use for the quantification of scapular AP tilt. Further study is warranted to establish reliability and to validate use of the device in patients with shoulder injury or pathology. The modified inclinometer expands the clinician's ability to quantify scapular kinematic motion during the clinical evaluation and rehabilitation process. LEVEL OF EVIDENCE: Level 3.

Sidelying glenohumeral passive internal rotation range of motion values in a healthy collegiate population.

PURPOSE/BACKGROUND: The sleeper stretch is a common intervention prescribed for individuals with decreased glenohumeral internal rotation. Passive glenohumeral internal rotation (GHIR) when quantified in sidelying has been suggested to be a more reliable measure as compared to measurments performed in supine with the humerus abducted to 908. Recently, the sidelying position has also been proposed as an evaluative measure to quantify GHIR. Minimal work however has described mean GHIR values in sidelying. Therefore, the objective of this study was to establish preliminary mean passive GHIR values in sidelying for a healthy, college-age population. Secondary purposes were to ascertain if mean values were affected by upper extremity dominance or sex. METHODS: Using a standardized protocol, passive GHIR was measured using a digital inclinometer on the dominant and non-dominant shoulders of 60 healthy, college-age participants (32 female [20.66±1.15 years, 170.70±14.38 cm, 63.34±7.51 kg] and 28 male [21.50±1.40 years, 183.81±13.17 cm, 90.04±17.91 kg]). RESULTS: The sidelying passive GHIR grand mean for all participants bilaterally was 50.4 ± 11.78. Mean passive GHIR values on the non-dominant side (52.7 ± 10.28) were greater than those on the dominant side (48.0 ± 12.58) (p = 0.002). There was no difference when GHIR values were compared by sex (p = 0.327) and a significant interaction between UE dominance and sex was not apparent (p = 0.693). CONCLUSIONS: In a healthy college age population, these preliminary data suggest GHIR values are statistically greater on the non-dominant side and that sex does not significantly affect GHIR measures in a sidelying position. LEVEL OF EVIDENCE: Level 3c.

Causation and management of calcific tendonitis and periarthritis.

PURPOSE OF REVIEW: The purpose of this review is to update the reader on contemporary theory related to the cause of calcific periarthritis and provide the latest evidence associated with treating recalcitrant cases. RECENT FINDINGS: Contemporary theory suggests calcific periarthritis is the result of a cellular-mediated process in which calcium is deposited and resorbed via a multiple phase process. Resorption is associated with an acute inflammatory response and is often the factor that prompts one to seek medical care. The majority of cases require nothing more than a combination of symptomatic care and benign neglect. A small percentage of cases require intervention to further stimulate deposit resorption. Moderate evidence exists for extracorporeal shock wave therapy in the treatment of chronic cases related to deposits about the shoulder. Numerous case studies support the use of NSAIDs as an effective intervention for retropharyngeal periarthritis. If conservative interventions fail, surgery appears to be a viable option for symptom relief associated with rotator cuff calcific deposits. SUMMARY: Periarthritis is typically a symptom-limiting condition that resolves spontaneously. Numerous conservative treatment modalities each with varying levels of evidence exist for use in refractory cases. Future study is necessary to further refine the efficacy and parameters associated with available interventions.

Validation and repeatability of a shoulder biomechanics data collection methodology and instrumentation.

The purpose of our study was to establish criterion-related validity and repeatability of a shoulder biomechanics testing protocol involving an electromagnetic tracking system (Flock of Birds [FoB]). Eleven subjects completed humeral elevation tasks in the sagittal, scapular, and frontal planes on two occasions. Shoulder kinematics were assessed with a digital inclinometer and the FoB. Intrasession and intersession repeatability for orthopedic angles, and humeral and scapular kinematics ranged from moderate to excellent. Correlation analyses revealed strong relationships between inclinometer and FoB measures of humeral motion, yet considerable mean differences were noted between the measurement devices. Our results validate use of the FoB for measuring humeral kinematics and establish our testing protocol as reliable. We must continue to consider factors that can impact system accuracy and the effects they may have on kinematic descriptions and how data are reported.

Successful removal of football helmet face-mask clips after 1 season of use.

CONTEXT: Whereas many researchers have assessed the ability to remove loop straps in traditional face-mask attachment systems after at least 1 season of use, research in which the effectiveness of the Riddell Quick Release (QR) Face Guard Attachment System clip after 1 season has been assessed is limited. OBJECTIVE: To examine the success rate of removing the QR clips after 1 season of use at the Football Championship Subdivision level. We hypothesized that 1 season of use would negatively affect the removal rate of the QR clip but repeated clip-removal trials would improve the removal rate. DESIGN: Retrospective, quasi-experimental design. SETTING: Controlled laboratory study. PATIENTS OR OTHER PARTICIPANTS: Sixty-three football helmets from a National Collegiate Athletic Association Division I university located in western Pennsylvania used during the 2008 season were tested. INTERVENTION(S): Three certified athletic trainers (2 men, 1 woman; age = 31.3 ± 3.06 years, time certified = 9.42 ± 2.65 years) attempted to remove the QR clips from each helmet with the tool provided by the manufacturer. Helmets then were reassembled to allow each athletic trainer to attempt clip removal. MAIN OUTCOME MEASURE(S): The dependent variables were total left clips removed (TCR-L), total right clips removed (TCR-R), and total clips removed (TCR). Success rate of clip removal (SRCR) also was assessed. RESULTS: Percentages for TCR-L, TCR-R, and TCR were 100% (189 of 189), 96.30% (182 of 189), and 98.15% (371 of 378), respectively. A paired-samples t test revealed a difference between TCR-R and TCR-L (t(188) = 2.689, P = .008, µ(d) = 0.037, 95% confidence interval [CI] = 0.064, 0.010). The percentage for SRCR was 96.30% (n = 182), whereas SRCR percentages for trials 1, 2, and 3 were 95.24% (n = 60), 98.41% (n = 62), and 95.24% (n = 60), respectively, and did not represent a difference (F(2,186) = 0.588, P = .56, 95% (CI) = 0.94, 0.99). CONCLUSIONS: Our results indicated favorable and consistent success rates for QR clip removal after 1 season of use. Whereas the QR clip is an advancement in face-mask technology, continued examination of this system is required to ensure the highest level of function, allowing for effective management of the helmeted athlete.

Assessment of scapulohumeral rhythm for scapular plane shoulder elevation using a modified digital inclinometer.

AIM: To develop a better understanding of scapulohumeral rhythm during scapular plane shoulder elevation. METHODS: Thirteen healthy, college-aged subjects participated in this study. Subjects were free from any upper extremity, neck or back pathology. A modified digital inclinometer was utilized to measure scapular upward rotation of the subject's dominant shoulder. Upward rotation was measured statically as subjects performed clinically relevant amounts of shoulder elevation in the scapular plane. Testing order was randomized by arm position. Scapular upward rotation was assessed over the entire arc of motion and over a series of increments. The percent contributions to shoulder elevation for the scapula and glenohumeral joint were calculated. Scapulohumeral rhythm was assessed and represented the ratio of glenohumeral motion to scapulothoracic motion (glenohumeral elevation: scapular upward rotation). A one-way ANOVA was used to compare scapular upward rotation between elevation increments. RESULTS: Scapulohumeral rhythm for the entire arc of shoulder elevation was equal to a ratio of 2.34 :1 and ranged from 40.01:1 to 0.90:1 when assessed across the different increments of humeral elevation. Total scapular motion increased over the arc of shoulder elevation. The scapula contributed 2.53% of total motion for the first 30 degrees of shoulder elevation, between 20.87% and 37.53% for 30(o)-90(o) of shoulder elevation, and 52.73% for 90(o)-120(o) of shoulder elevation. Statistically significant differences in scapular upward rotation were identified across the shoulder elevation increments [F((3,48)) = 12.63, P = 0.0001]. CONCLUSION: Clinically, we must recognize the usefulness of the inclinometer in documenting the variable nature of scapulohumeral rhythm in healthy and injured shoulders.

Time to peak force is related to frontal plane landing kinematics in female athletes.

OBJECTIVES: Determine the relationship between unilateral lower extremity closed kinetic chain muscle performance and unilateral frontal plane landing kinematics. DESIGN: Descriptive. SETTING: Outpatient physical therapy clinic. PARTICIPANTS: Twenty adolescent female athletes. MAIN OUTCOME MEASURES: Unilateral lower extremity muscle performance was quantified at 25° of knee flexion on a computerized leg press. Unilateral frontal plane tibiofemoral kinematics were captured with a bi-axial electrogoniometer during a drop jump maneuver from a 40 cm platform. RESULTS: Peak and average force and force normalized to body weight were not significantly related to frontal plane landing kinematics. Time to peak force however was related to both frontal plane initial contact (r = -0.54; P = 0.013) and peak angles at 100 ms post-contact (r = -0.53; P = 0.016). As time to peak force increased, tibiofemoral angles were in greater amounts of valgus. CONCLUSIONS: During an isometric closed kinetic chain unilateral squat test at 25 degrees of knee flexion, the time to peak force is related to frontal plane landing kinematics. Females who take longer to generate peak force are more likely to exhibit valgus kinematic patterns during the landing task. However, strength measures (peak force, average force or peak and average force normalized to body weight) are not associated with unilateral landing kinematics in female athletes.

Presentation and conservative management of acute calcific tendinopathy: a case study and literature review.

BACKGROUND: The efficacy of a variety of noninvasive, conservative management techniques for calcific tendinopathy has been investigated and established for improving pain and function and/or facilitating a decrease in the size or presence of calcium deposits. Surprisingly, few have reported on the use of traditional therapeutic exercise and rehabilitation alone in the management of this condition, given the often spontaneous resorptive nature of calcium deposits. The purpose of this case is to present the results of a conservative approach, including therapeutic exercise, for the management of calcific tendinopathy of the supraspinatus, with an emphasis on patient outcomes. CASE DESCRIPTION: The patient was a self-referred 41-y-old man with complaints of acute right-shoulder pain and difficulty sleeping. Imaging studies revealed liquefied calcium deposits in the right supraspinatus. The patient reported constant pain at rest (9/10) and tenderness in the area of the greater tuberosity. He exhibited a decrease in all shoulder motions and had reduced strength. The simple shoulder test (SST) revealed limited function (0/12). Conservative management included superficial modalities and medication for pain and a regimen of scapulothoracic and glenohumeral range-of-motion (ROM) and strengthening exercises. OUTCOMES: At discharge, pain levels decreased to 0/10 and SST scores increased to 12/12. ROM was full in all planes, and resisted motion was strong and pain free. The patient was able to engage in endurance activities and continue practicing as a health care provider. DISCUSSION: The outcomes with respect to pain, function, and patient satisfaction provide evidence to support the use of conservative therapeutic interventions when managing patients with acute cases of calcific tendinopathy. Successful management of calcific tendinopathy requires attention to outcomes and an understanding of the pathophysiology, prognostic factors, and physical interventions based on the current stage of the calcium deposits and the patient's status in the healing continuum.

The relationship between lower extremity closed kinetic chain strength & sagittal plane landing kinematics in female athletes.

BACKGROUND: Female athletes continue to injure their anterior cruciate ligaments at a greater rate than males in comparable sports. During landing activities, females exhibit several different kinematic and kinetic traits when compared to their male counterparts including decreased knee flexion angles as well as decreased lower extremity (LE) strength. While open kinetic chain strength measures have not been related to landing kinematics, given the closer replication of movement patterns that occur during closed kinetic chain (CKC) activity, it is possible that lower extremity strength if measured in this fashion will be related to landing kinematics. PURPOSE: To determine if unilateral isometric CKC lower extremity (LE) strength was related to sagittal plane tibiofemoral kinematics during a single leg landing task in competitive female athletes. We hypothesized females who demonstrated lesser CKC LE strength would exhibit decreased sagittal plane angles during landing. METHODS: 20 competitive female athletes (age = 16.0 ± 1.8 yrs; height = 166.5 ± 8.3 cm; weight = 59.7 ± 10.2 kg) completed CKC LE strength testing followed by 5 unilateral drop landings on the dominant LE during one test session at an outpatient physical therapy clinic. Closed kinetic chain LE strength was measured on a computerized leg press with an integrated load cell while sagittal plane tibiofemoral kinematics were quantified with an electrogoniometer. RESULTS: No significant relationships between absolute or normalized isometric CKC strength and sagittal plane landing kinematics were identified. CONCLUSIONS: Closed kinetic chain lower extremity isometric strength tested at 25 degrees of knee flexion is not related to sagittal plane landing kinematics in adolescent competitive female athletes. LEVELS OF EVIDENCE: Analytic, Observational.

Rotator cuff tear pain and tear size and scapulohumeral rhythm.

CONTEXT: The body of knowledge concerning shoulder kinematics in patients with rotator cuff tears is increasing. However, the level of understanding regarding how pain and tear size affect these kinematic patterns is minimal. OBJECTIVE: To identify relationships between pain associated with a full-thickness rotator cuff tear, tear size, and scapulohumeral rhythm (SHR) and to determine whether pain and tear size serve as predictors of SHR. DESIGN: A test-retest design was used to quantify pain and SHR before and after a subacromial lidocaine injection. Correlation and multivariate analyses were used to identify relationships among pain, tear size, and SHR. SETTING: Orthopaedic biomechanics research laboratory. PATIENTS OR OTHER PARTICIPANTS: Fifteen patients (age range, 40-75 years) with diagnosed full-thickness rotator cuff tears participated. They were experiencing pain at the time of testing. INTERVENTION(S): Shoulder kinematic data were collected with an electromagnetic tracking system before and after the patient received a lidocaine injection. MAIN OUTCOME MEASURE(S): Pain was rated using a visual analog scale. Three-dimensional scapular kinematics and glenohumeral elevation were assessed. Scapular kinematics included anterior-posterior tilt, medial-lateral tilt, and upward-downward rotation. A regression model was used to calculate SHR (scapular kinematics to glenohumeral elevation) for phases of humeral elevation and lowering. RESULTS: Linear relationships were identified between initial pain scores and SHR and between tear size and SHR, representing an increased reliance on scapular motion with increasing pain and tear size. Pain was identified as an independent predictor of SHR, whereas significant findings for the effect of tear size on SHR and the interaction between pain and tear size were limited. CONCLUSIONS: We noted an increased reliance on scapular contributions to overall humeral elevation with increasing levels of pain and rotator cuff tear size. Pain associated with a rotator cuff tear serves as a primary contributor to the kinematic patterns exhibited in patients with rotator cuff tears.

Shoulder kinematics in patients with full-thickness rotator cuff tears after a subacromial injection.

The purpose of this study was to test the hypothesis that scapulohumeral rhythm (SHR) is altered in patients with full-thickness rotator cuff tears due to pain. Fifteen subjects (mean age, 60.2 +/- 8.9 years; mean height, 1.72 +/- 0.10 m; mean weight, 85.43 +/- 18.32 kg) performed humeral elevation in the 3 planes before and after a lidocaine injection. Pain was assessed by use of a visual analog scale, and data were collected with an electromagnetic tracking system. Three-dimensional scapular kinematics (scapulothoracic motion) and glenohumeral elevation were assessed. A linear regression model was used to calculate SHR (ratio of scapulothoracic motion to glenohumeral elevation) for equal phases of elevation (I, II, and III) and lowering (IV, V, and VI). Pain was significantly reduced (P

Correlation of range of motion and glenohumeral translation in professional baseball pitchers.

BACKGROUND: Altered mobility patterns in the throwing shoulders of professional baseball pitchers have been reported. Most published reports examining glenohumeral laxity have not used an objective testing device. OBJECTIVE: Quantify and compare glenohumeral translation and rotational range of motion between the throwing and non-throwing shoulders in professional baseball pitchers. STUDY DESIGN: Descriptive laboratory study. METHODS: Force-displacement and range of motion measures were performed bilaterally on 43 asymptomatic professional baseball pitchers. Ultrasound imaging was used to measure glenohumeral translations under stressed and unstressed conditions. RESULTS: No significant difference in translation was found between the throwing and nonthrowing shoulders. For both shoulders, posterior translation (5.38 +/- 2.7 mm) was significantly greater (P < .001) than was anterior translation (2.81 +/- 1.6 mm). External rotation in the throwing shoulder was significantly greater than that in the nonthrowing shoulder (P < .001), whereas internal rotation in the throwing shoulder was significantly less than that in the nonthrowing shoulder (P < .001). The total arc of rotation for the throwing shoulder was not significantly different than that for the nonthrowing shoulder, and correlation coefficients were poor between rotational and translational range of motion in the throwing shoulder, ranging from r = 0.232 to 0.209 between variables. CONCLUSION: No significant difference in glenohumeral translation exists between the throwing and nonthrowing shoulders in asymptomatic professional baseball pitchers, posterior translation is significantly greater than anterior translation in the throwing shoulders of professional baseball pitchers, and glenohumeral translation is not related to rotational range of motion in the throwing shoulders of professional baseball pitchers. CLINICAL RELEVANCE: Altered mobility patterns in asymptomatic professional baseball pitchers may be due to factors other than capsular adaptive changes.

Sonographic stress measurement of glenohumeral joint laxity in collegiate swimmers and age-matched controls.

BACKGROUND: Glenohumeral laxity that is greater than normal has been implicated as a causal factor in the development of shoulder pain and dysfunction in elite swimmers; however, quantitative evidence demonstrating greater-than-normal glenohumeral joint laxity in swimmers is lacking. OBJECTIVE: To quantify glenohumeral joint laxity in elite swimmers and nonswimming controls using stress sonography. STUDY DESIGN: Controlled laboratory study. METHODS: Force-displacement measures were performed bilaterally in 42 National Collegiate Athletic Association Division I swimmers and 44 age-matched controls. Of the 42 swimmers, 27 (64%) reported a history of unilateral or bilateral shoulder pain resulting from swimming. Ultrasound imaging was used to measure glenohumeral joint displacement under stressed and non-stressed conditions. RESULTS: An analysis of variance revealed no significant difference in glenohumeral joint displacement between swimmers (anterior, 2.82 +/- 1.7 mm; posterior, 5.30 +/- 2.4 mm) and age-matched controls (anterior, 2.74 +/- 1.7 mm; posterior, 4.90 +/- 2.7 mm). No significant difference in glenohumeral joint displacement was found between swimmers with a history of shoulder pain (anterior, 2.90 +/- 1.6 mm; posterior, 5.42 +/- 2.3 mm) versus swimmers without a history of shoulder pain (anterior, 2.74 +/- 1.8 mm; posterior, 5.14 +/- 2.6 mm). Shoulders displayed significantly more glenohumeral joint displacement in the posterior direction compared to the anterior direction (P < .001). CONCLUSIONS: Our instrumented technique was unable to identify significantly greater glenohumeral joint displacement in elite swimmers compared to nonswimming controls, and elite swimmers with a history of shoulder pain were not found to have significantly more glenohumeral joint displacement compared to swimmers without a history of shoulder pain. CLINICAL RELEVANCE: Objective assessment of glenohumeral joint displacement in athletes participating in overhead-motion sports may be important for injury prevention and management.