Vasilios Moutzouros

In Vivo Shoulder Function After Surgical Repair of a Torn Rotator Cuff Glenohumeral Joint Mechanics, Shoulder Strength, Clinical Outcomes, and Their Interaction

Background: Surgical repair of a torn rotator cuff is based on the belief that repairing the tear is necessary to restore normal glenohumeral joint (GHJ) mechanics and achieve a satisfactory clinical outcome. Hypothesis: Dynamic joint function is not completely restored by rotator cuff repair, thus compromising shoulder function and potentially leading to long-term disability. Study Design: Controlled laboratory study and Case series; Level of evidence, 4. Methods: Twenty-one rotator cuff patients and 35 control participants enrolled in the study. Biplane radiographic images were acquired bilaterally from each patient during coronal-plane abduction. Rotator cuff patients were tested at 3, 12, and 24 months after repair of a supraspinatus tendon tear. Control participants were tested once. Glenohumeral joint kinematics and joint contact patterns were accurately determined from the biplane radiographic images. Isometric shoulder strength and patient-reported outcomes were measured at each time point. Ultrasound imaging assessed rotator cuff integrity at 24 months after surgery. Results: Twenty of 21 rotator cuff repairs appeared intact at 24 months after surgery. The humerus of the patients’ repaired shoulder was positioned more superiorly on the glenoid than both the patients’ contralateral shoulder and the dominant shoulder of control participants. Patient-reported outcomes improved significantly over time. Shoulder strength also increased over time, although strength deficits persisted at 24 months for most patients. Changes over time in GHJ mechanics were not detected for either the rotator cuff patients’ repaired or contralateral shoulders. Clinical outcome was associated with shoulder strength but not GHJ mechanics. Conclusion: Surgical repair of an isolated supraspinatus tear may be sufficient to keep the torn rotator cuff intact and achieve satisfactory patient-reported outcomes, but GHJ mechanics and shoulder strength are not fully restored with current repair techniques. Clinical Relevance: The study suggests that current surgical repair techniques may be effective for reducing pain but have not yet been optimized for restoring long-term shoulder function.

Pre- and Postseason Dynamic Ultrasound Evaluation of the Pitching Elbow

PURPOSEnTo use ultrasound imaging to document changes over time (i.e., preseason v postseason) in the pitching elbow of high school baseball pitchers.nnnMETHODSnTwenty-two high school pitchers were prospectively followed. Pitchers were evaluated after a 2-month period of relative arm rest via preseason physical exams, dynamic ultrasound imaging of their throwing elbow, and the Quick Disabilities of the Arm, Shoulder, and Hand (QuickDASH) assessment. Players were reevaluated within 1 week of their last game. Dynamic ultrasound images were then randomized, blinded to testing time point, and evaluated by 2 fellowship-trained musculoskeletal radiologists.nnnRESULTSnAverage pitcher age was 16.9 years. Average pitches thrown was 456.5, maximum velocity 77.7 mph, games pitched 7.3, and days off between starts 6.6. From preseason to postseason, there were significant increases in ulnar collateral ligament (UCL) thickness (P = .02), ulnar nerve cross-sectional area (P = .001), UCL substance heterogeneity (P = .001), and QuickDASH scores (P = .03). In addition, there was a nonsignificant increase in loaded ulnohumeral joint space (P = .10). No pitchers had loose bodies on preseason exam, while 3 demonstrated loose bodies postseason. The increase in UCL thickness was significantly associated with the number of bullpen sessions per week (P = .01). The increase in ulnar nerve cross-sectional area was significantly associated with the number of pitches (P = .04), innings pitched (P = .01), and games pitched (P = .04).nnnCONCLUSIONSnThe stresses placed on the elbow during only one season of pitching create adaptive changes to multiple structures about the elbow including UCL heterogeneity and thickening, increased ulnohumeral joint space laxity, and enlarged ulnar nerve cross-sectional area.nnnLEVEL OF EVIDENCEnLevel II prospective observational study.

Assessment of Elbow Torque and Other Parameters During the Pitching Motion: Comparison of Fastball, Curveball, and Change-up

PURPOSEnTo assess the precision of a new wearable device in detecting medial elbow torque during the pitching motion in competitive baseball pitchers and to determine the differences in torque across pitch types and thrower demographic characteristics.nnnMETHODSnHigh school and collegiate baseball pitchers were recruited from August 1, 2016, to January 31, 2017, through direct request by athletic trainers and coaches. Body dimensions and throwing arm measurements of the participants were collected. The sensor was positioned directly over the medial elbow and pitchers were instructed to throw 8 fastballs, 8 curveballs, and 8 change-ups in a standard, randomized sequence. The sensor reported elbow torque, arm speed, arm slot, and shoulder rotation, whereas a radar gun measured peak ball velocity. Precision was calculated by measuring outlier rate, and mixed model regression analysis was performed to detect differences in throwing biomechanics among pitch types.nnnRESULTSnIn total, 37 competitive baseball pitchers were included in the study. The device had a precision of 96.9% for fastballs, 96.9% for curveballs, and 97.9% for change-ups. The device was sensitive enough to distinguish pitches according to elbow torque, arm speed, arm slot, and shoulder rotation. Fastballs caused the greatest relative torque across the medial elbow (averagexa0= 45.56xa0Nxa0m), compared with change-ups (43.77xa0Nxa0m; Pxa0= .006) and curveballs (43.83xa0Nxa0m; Pxa0= .01). Ball velocity contributed most to medial elbow torque (Pxa0= .003), followed by elbow circumference (Pxa0= .021), where smaller elbow circumference predicted greater medial elbow torque.nnnCONCLUSIONSnThe sensor is a precise and reproducible device for measuring torque across the medial elbow, as well as additional parameters of arm speed, arm slot, and shoulder rotation. Torque was significantly relatively higher in fastballs than curveballs and change-ups.nnnLEVEL OF EVIDENCEnLevel III, comparative study.

Associations between in-vivo glenohumeral joint motion and morphology.

Joint morphology has a significant influence on joint motion and may contribute to the development of rotator cuff pathology, but the relationships between glenohumeral joint (GHJ) morphology and in-vivo GHJ motion are not well understood. The objectives of this study were to assess measures of joint morphology and their relationship with in-vivo joint motion in two populations: shoulders with intact rotator cuffs (n=48) and shoulders with rotator cuff pathology (n=36, including 5 symptomatic tears, 9 asymptomatic tears and 22 repaired tears). GHJ morphology was measured from CT-based three-dimensional models of the humerus and scapula. In-vivo GHJ motion was measured during shoulder abduction using biplane x-ray imaging. Associations between GHJ morphology and motion were assessed with univariate and best subsets regression. The only morphological difference identified between the populations was the critical shoulder angle (intact: 34.5 ± 4.7°, pathologic: 36.9 ± 5.0°, p=0.03), which is consistent with previous research. In intact shoulders, the superior/inferior (S/I) position of the humerus on the glenoid during shoulder abduction was significantly associated with the glenoids S/I radius of curvature (p<0.01), conformity index (p<0.01), and stability angle (p<0.01). Furthermore, the S/I position of the humerus on the glenoid was negatively associated with the critical shoulder angle (p=0.04), which contradicts previous research. No significant associations between GHJ morphology and GHJ motion were detected in shoulders with rotator cuff tears. It is unknown if rotator cuff pathology compromises the relationships between GHJ morphology and motion, or if the absence of this relationship is a pre-existing condition that increases the likelihood of pathology.

Measuring Dynamic In-Vivo Elbow Kinematics: Description of Technique and Estimation of Accuracy

BACKGROUNDnThe objectives of this study were to characterize the translational and rotational accuracy of a model-based tracking technique for quantifying elbow kinematics and to demonstrate its in vivo application.nnnMETHOD OF APPROACHnThe accuracy of a model-based tracking technique for quantifying elbow kinematics was determined in an in vitro experiment. Biplane X-ray images of a cadaveric elbow were acquired as it was manually moved through flexion-extension. The 3D position and orientation of each bone was determined using model-based tracking. For comparison, the position and orientation of each bone was also determined by tracking the position of implanted beads with dynamic radiostereometric analysis. Translations and rotations were calculated for both the ulnohumeral and radiohumeral joints, and compared between measurement techniques. To demonstrate the in vivo application of this technique, biplane X-ray images were acquired as a human subject extended their elbow from full flexion to full extension.nnnRESULTSnThe in vitro validation demonstrated that the model-based tracking technique is capable of accurately measuring elbow motion, with reported errors averaging less than ±1.0u2009mm and ±1.0u2009deg. For the in vivo application, the carrying angle changed from an 8.3u2009±u20090.5u2009deg varus position in full flexion to an 8.4u2009±u20090.5u2009deg valgus position in full extension.nnnCONCLUSIONSnModel-based tracking is an accurate technique for measuring in vivo, 3D, dynamic elbow motion. It is anticipated that this experimental approach will enhance our understanding of elbow motion under normal and pathologic conditions.

Effects of Rotator Cuff Pathology and Physical Therapy on In Vivo Shoulder Motion and Clinical Outcomes in Patients With a Symptomatic Full-Thickness Rotator Cuff Tear

Background: Physical therapy (PT) is often prescribed for patients with rotator cuff tears. The extent to which PT influences strength, range of motion (ROM), and patient-reported outcomes has been studied extensively, but the effect of PT on in vivo joint kinematics is not well understood. Purpose: To assess the influence of symptomatic rotator cuff pathology and the effects of PT on shoulder motion, strength, and patient-reported outcomes. Study Design: Controlled laboratory study. Methods: Twenty-five patients with a symptomatic rotator cuff tear and 25 age-matched asymptomatic control subjects were recruited. Shoulder motion was measured using a biplane radiography imaging system, strength was assessed with a Biodex dynamometer, and patient-reported outcomes were assessed using the Western Ontario Rotator Cuff Index and visual analog scale (VAS) pain scores. Data were acquired from the patients before and after 8 weeks of physical therapy. Data were acquired at 1 time point for the control subjects. Results: Compared with the control subjects, patients with a symptomatic rotator cuff tear had significantly worse pain/function scores (P < .01); less ROM (P < .01); lower abduction (ABD), external rotation (ER), and internal rotation (IR) strength (P < .01); less scapulothoracic posterior tilt (P = .05); and lower glenohumeral joint elevation (P < .01). Physical therapy resulted in improved pain/function scores (P < .01), increased ROM (P < .02), increased scapulothoracic posterior tilt (P = .05), increased glenohumeral joint elevation (P = .01), and decreased acromiohumeral distance (AHD) (P = .02). Conclusion: Compared with age-matched controls, patients had worse pain/function scores, less ROM, and lower ABD, ER, and IR strength. Patients also had less scapulothoracic anteroposterior tilt, less glenohumeral joint elevation, and an altered glenohumeral joint contact path. PT resulted in improved pain/function scores, increased ROM, greater posterior scapulothoracic tilt, increased glenohumeral joint elevation, an increased range of superoinferior joint contact, and a lower mean AHD. Of these differences, PT only returned scapulothoracic tilt to control levels. Clinical Relevance: This study documents the effects of PT on shoulder motion and conventional clinical outcomes. It is expected that understanding how changes in joint motion are associated with conventional clinical outcomes will lead to improved nonoperative interventions for patients with rotator cuff tears.

Shear wave elastography of the supraspinatus muscle and tendon: Repeatability and preliminary findings

Shear wave elastography (SWE) is a promising tool for estimating musculoskeletal tissue properties, but few studies have rigorously assessed its repeatability and sources of error. The objectives of this study were to assess: (1) the extent to which probe positioning error and human user error influence measurement accuracy, (2) intra-user, inter-user, and day-to-day repeatability, and (3) the extent to which active and passive conditions affect shear wave speed (SWS) repeatability. Probe positioning and human usage errors were assessed by acquiring SWE images from custom ultrasound phantoms. Intra- and inter-user repeatability were assessed by two users acquiring five trials of supraspinatus muscle and tendon SWE images from ten human subjects. To assess day-to-day repeatability, five of the subjects were tested a second time, approximately 24h later. Imaging of the phantoms indicated high inter-user repeatability, with intraclass correlation coefficient (ICC) values of 0.68-0.85, and RMS errors of no more than 4.1%. SWE imaging of the supraspinatus muscle and tendon had high repeatability, with intra- and inter-user ICC values of greater than 0.87 and 0.73, respectively. Day-to-day repeatability demonstrated ICC values greater than 0.33 for passive muscle, 0.48 for passive tendon, 0.65 for active muscle, and 0.94 for active tendon. This study indicates the technique has good to very good intra- and inter-user repeatability, and day-to-day repeatability is appreciably higher when SWE images are acquired under a low level of muscle activation. The findings from this study establish the feasibility and repeatability of SWE for acquiring data longitudinally in human subjects.

Performance, Return to Play, and Career Longevity After Ulnar Collateral Ligament Reconstruction in Professional Catchers

PURPOSEnThe purpose of our study was to evaluate return to play and postinjury performance of professional catchers who sustained an ulnar collateral ligament (UCL) rupture requiring surgical reconstruction. We looked to evaluate these players to determine the rate of return to play, the level of return to play, and career longevity after surgery as well as how statistical performance is affected by reconstruction.nnnMETHODSnTwenty-five professional catchers who underwent UCL reconstruction between 1985 and 2015 were identified and compared with an age-, position-, and competition-matched control group. Priority was placed on level of play, year of injury, age, and years played prior to injury in matching controls. Injury information and demographic data (age at injury, level of play, and career length) were collected from publicly available team websites and press releases. Offensive and defensive performance statistics were collected for 3xa0years prior to injury and 3xa0years after return. Return to play, return to level of play, and career after return were also analyzed.nnnRESULTSnThe average age at time of UCL injury was 24.4 (standard deviation, 4.5) years old. Return to play for all catchers was 80% (20/25), with only one player not returning to the same previous level of play (95%). Average years in Major League Baseball (MLB) after return was 2.3xa0years versus 2.6xa0years in the control group (Pxa0= .07), with 4.3xa0years total (MLB and minors) versus 3.8xa0years total in the control group (Pxa0= .28). There were no changes in offensive or defensive performance before and after injury.nnnCONCLUSIONSnUCL reconstruction in professional catchers can lead to successful outcomes. Catchers can expect a high rate of return to play with high rate of return to previous level of play, similar performance, and no change in career longevity following return from UCL reconstruction.nnnSTUDY DESIGNnLevel III, case-control series.

The Effects of Age and Pathology on Shear Wave Speed of the Human Rotator Cuff

Rotator cuff tears are common and often repaired surgically, but post‐operative repair tissue healing, and shoulder function can be unpredictable. Tear chronicity is believed to influence clinical outcomes, but conventional clinical approaches for assessing tear chronicity are subjective. Shear wave elastography (SWE) is a promising technique for assessing soft tissue via estimates of shear wave speed (SWS), but this technique has not been used extensively on the rotator cuff. Specifically, the effects of age and pathology on rotator cuff SWS are not well known. The objectives of this study were to assess the association between SWS and age in healthy, asymptomatic subjects, and to compare measures of SWS between patients with a rotator cuff tear and healthy, asymptomatic subjects. SWE images of the supraspinatus muscle and intramuscular tendon were acquired from 19 asymptomatic subjects and 11 patients with a rotator cuff tear. Images were acquired with the supraspinatus under passive and active (i.e., minimal activation) conditions. Mean SWS was positively associated with age in the supraspinatus muscle and tendon under passive and active conditions (pu2009≤u20090.049). Compared to asymptomatic subjects, patients had a lower mean SWS in their muscle and tendon under active conditions (pu2009≤u20090.024), but no differences were detected under passive conditions (pu2009≥u20090.783). These findings identify the influences of age and pathology on SWS in the rotator cuff. These preliminary findings are an important step toward evaluating the clinical utility of SWE for assessing rotator cuff pathology.

Effects of asymptomatic rotator cuff pathology on in vivo shoulder motion and clinical outcomes

BACKGROUNDnThe incidence of asymptomatic rotator cuff tears has been reported to range from 15% to 39%, but the influence of asymptomatic rotator cuff pathology on shoulder function is not well understood. This study assessed the effects of asymptomatic rotator cuff pathology on shoulder kinematics, strength, and patient-reported outcomes.nnnMETHODSnA clinical ultrasound examination was performed in 46 asymptomatic volunteers (age: 60.3u2009±u20097.5 years) with normal shoulder function to document the condition of their rotator cuff. The ultrasound imaging identified the participants as healthy (nu2009=u200914) or pathologic (nu2009=u200932). Shoulder motion was measured with a biplane x-ray imaging system, strength was assessed with a Biodex (Biodex Medical Systems, Inc., Shirley, NY, USA), and patient-reported outcomes were assessed using the Western Ontario Rotator Cuff Index and visual analog scale pain scores.nnnRESULTSnCompared with healthy volunteers, those with rotator cuff pathology had significantly less abduction (Pu2009=u2009.050) and elevation (Pu2009=u2009.041) strength, their humerus was positioned more inferiorly on the glenoid (Pu2009=u2009.018), and the glenohumeral contact path length was longer (Pu2009=u2009.007). No significant differences were detected in the Western Ontario Rotator Cuff Index, visual analog scale, range of motion, or acromiohumeral distance.nnnCONCLUSIONSnThe differences observed between the healthy volunteers and those with asymptomatic rotator cuff pathology lend insight into the changes in joint mechanics, shoulder strength, and conventional clinical outcomes associated with the early stages of rotator cuff pathology. Furthermore, these findings suggest a plausible mechanical progression of kinematic and strength changes associated with the development of rotator cuff pathology.