Sheryl Finucane

Mechanisms of rotator cuff tendinopathy: intrinsic, extrinsic, or both?

The etiology of rotator cuff tendinopathy is multi-factorial, and has been attributed to both extrinsic and intrinsic mechanisms. Extrinsic factors that encroach upon the subacromial space and contribute to bursal side compression of the rotator cuff tendons include anatomical variants of the acromion, alterations in scapular or humeral kinematics, postural abnormalities, rotator cuff and scapular muscle performance deficits, and decreased extensibility of pectoralis minor or posterior shoulder. A unique extrinsic mechanism, internal impingement, is attributed to compression of the posterior articular surface of the tendons between the humeral head and glenoid and is not related to subacromial space narrowing. Intrinsic factors that contribute to rotator cuff tendon degradation with tensile/shear overload include alterations in biology, mechanical properties, morphology, and vascularity. The varied nature of these mechanisms indicates that rotator cuff tendinopathy is not a homogenous entity, and thus may require different treatment interventions. Treatment aimed at addressing mechanistic factors appears to be beneficial for patients with rotator cuff tendinopathy, however, not for all patients. Classification of rotator cuff tendinopathy into subgroups based on underlying mechanism may improve treatment outcomes.

The Effects of Low-Intensity Ultrasound on Medial Collateral Ligament Healing in the Rabbit Model

Background Ruptured medial collateral ligaments are capable of healing over time, but biomechanical and biochemical properties remain inferior to normal tissue. Low-intensity ultrasound may improve healing. Hypothesis Medial collateral ligaments treated with ultrasound will demonstrate superior healing. Study Design Controlled laboratory study. Methods Twenty-one late-adolescent male rabbits underwent bilateral ligament transection. One ligament from each rabbit received ultrasound treatment every other day for 6 total treatments. Contralateral ligaments received sham treatments. After 3 or 6 weeks, ligaments were evaluated biomechanically and assayed for collagen concentration and the relative proportions of types I and III collagen. Results Areas of sonicated specimens were significantly larger (10.6% ± 4.90%) at 6 weeks. Ultimate load (39.5% ± 17.0%), ultimate displacement (24.5% ± 8.0%), and energy absorption (69.1% ± 22.0%) were significantly higher for sonicated specimens at 6 weeks. No significant biomechanical differences were observed at 3 weeks. The relative proportion of type I collagen was significantly higher in sonicated ligaments at 3 weeks (8.61% ± 4.0%) and 6 weeks (6.91% ± 3.0%). No significant differences in collagen concentration were observed at either 3 or 6 weeks. Conclusion Subtle improvement with ultrasound treatment may be apparent by 3 weeks after injury, suggested by increased proportion of type I collagen. Ultrasound appears to improve some structural properties and to modestly increase scar cross-sectional area and type I collagen present at 6 weeks after injury in this model. Clinical Relevance Ultrasound treatments after ligament injury may facilitate earlier return to activities and decrease risk of reinjury.

Quantifying Exertion Level During Exercise Stress Testing Using Percentage of Age-Predicted Maximal Heart Rate, Rate Pressure Product, and Perceived Exertion

OBJECTIVE To determine if the attainment of at least 85% of age-predicted maximal heart rate (APMHR), using the equation 220 - age, and/or at least 25,000 as the product of maximal heart rate and systolic blood pressure (rate pressure product, RPP) is an accurate indicator of exertion level during exercise stress testing. PATIENTS AND METHODS From May 1, 2009, to February 15, 2010, 238 patients (mean ± SD age, 49.3±11.9 years; 50% male) with symptoms suggestive of myocardial ischemia underwent an exercise stress test with the addition of ventilatory expired gas analysis and a myocardial perfusion study. Ventilatory expired gas analysis determined the peak respiratory exchange ratio (RER), which is considered a valid and reliable variable for quantifying a patients exertion during exercise. RESULTS Of the patients, 207 (87%) attained a peak RER of 1.00 or more, and 123 (52%) attained a peak RER of 1.10 or more. An APMHR of 85% or more and peak RPP of 25,000 or more were both ineffective in identifying patients who put forth a maximal exercise effort (ie, peak RER, ≥1.10). Perceived exertion was a significant indicator (P=.04) of patient exertion, with a threshold of 15 (6-20 scale) being an optimal cut point. The percentage of equivocal myocardial perfusion study results was significantly higher in patients who demonstrated a submaximal exercise effort by peak RER (P≤.007). CONCLUSION Aerobic exercise testing is an integral component in the assessment of patients with suspected myocardial ischemia. Our findings indicate that the currently used percentage of APMHR and peak RPP thresholds are ineffective in quantifying a patients level of exertion during exercise stress testing.

Reproducibility of electromyographic recordings of submaximal concentric and eccentric muscle contractions in humans

OBJECTIVES to determine the intratester and intertester reliability of measures of electromyographic activity (EMG) of submaximal concentric and eccentric contractions and to compare the reliability of normalized and non-normalized measures of EMG. There were 10 subjects, of 22-33 years old. METHODS Subjects performed submaximal concentric and eccentric contractions at 60 degrees/s, and maximal isometric contractions (MIC) of their knee extensors. The target power of the submaximal contractions was 90%+/-10% of the subjects maximal concentric power. EMG was recorded via bipolar surface electrodes from 3 of the quadriceps femoris muscles. The rmsEMG for submaximal contractions that were within the target power range were determined. The rmsEMG for the submaximal contractions were normalized to the rmsEMG of the maximal isometric contractions. Intraclass correlation coefficients (ICC version 1.1) were calculated to determine intratester and intertester reliability. RESULTS For non-normalized rmsEMG, ICC values for intratester reliability ranged from 0.62 to 0.91 for concentric and from 0.84 to 0.97 for eccentric contractions. ICC values for intertester reliability ranged from 0.66 to 0.96 for concentric and 0.78 to 0.90 for eccentric contractions. CONCLUSIONS Non-normalized rmsEMG of submaximal concentric and eccentric isokinetic contractions were found to be reliable. Normalization did not lead to consistently improved reliability.

The Scapular Assistance Test Results in Changes in Scapular Position and Subacromial Space but Not Rotator Cuff Strength in Subacromial Impingement

STUDY DESIGN Controlled laboratory study. OBJECTIVES To determine the effect of the modified scapular assistance test (SAT) on 3-dimensional shoulder kinematics, strength, and linear measures of subacromial space in patients with subacromial impingement syndrome (SAIS). BACKGROUND Abnormal scapular kinematics have been identified in patients with SAIS. Increased scapular upward rotation and posterior tilt, as induced with manual assistance using the SAT, have been theorized to increase subacromial space and may alter shoulder strength. METHODS Forty-two subjects (21 with SAIS and 21 controls) participated in this study. The anterior outlet of the subacromial space, measured via the acromiohumeral distance on ultrasound images, and 3-dimensional scapular kinematics, measured using motion analysis, were determined with the arm at rest, and at 45° and 90° of active elevation with and without the SAT. A dynamometer was used to measure isometric shoulder strength. Full factorial mixed-model analyses of variance evaluated the effects of the SAT on variables between groups. RESULTS There was an increase in scapular posterior tilt at all angles, upward rotation at rest and 45° of elevation, and acromiohumeral distance at 45° and at 90° with the SAT. The SAT did not alter normalized isometric strength. There were no differences in response to the SAT between the SAIS and control groups. CONCLUSIONS Manual scapular assistance using the SAT influences factors associated with SAIS, such as subacromial space and potentially scapular orientation during static arm elevation, but not more so in individuals with SAIS than in healthy individuals. The SAT performed statically may be a way to identify potential subgroups of individuals with SAIS for whom subacromial space narrowing may be a contributing factor.

Usefulness of decrease in oxygen uptake efficiency slope to identify myocardial perfusion defects in men undergoing myocardial ischemic evaluation.

Cardiopulmonary exercise testing (CPX) might aid in the diagnosis of coronary artery disease. However, a heterogeneous clinical population without previous workup bias has not been studied nor has a more extensive list of CPX variables. A total of 303 subjects (age 49.9 ± 11.6 years, 157 men) with symptoms suggestive of coronary artery disease underwent CPX and a single photon emission computed tomographic myocardial perfusion study (MPS). Ventilatory efficiency was calculated using the oxygen uptake efficiency slope (OUES). The change in the OUES was calculated by subtracting the OUES response during the first 50% of CPX from the OUES obtained during the last 25% of CPX. A negative change in the OUES (< 0) from the first 50% to the last 25% of CPX was predictive of positive MPS findings only in the male subjects. The diagnostic significance of the change in OUES in men was found for any level (including equivocal studies) of positive MPS findings (area under the curve 0.67, 95% confidence interval 0.59 to 0.76, p < 0.0001) and was even stronger in those with a more definitive (excluding equivocal studies) perfusion defect (area under the curve 0.76, 95% confidence interval 0.67 to 0.85; relative risk 5.4, 95% confidence interval 2.1 to 13.8, p < 0.0001). In conclusion, this is the first time that a change in ventilatory efficiency, assessed using the OUES, has been shown to be predictive of positive MPS findings However, the OUES change only provided diagnostic information for men, a finding that warrants additional analysis.

Immediate changes in pressure pain sensitivity after thoracic spinal manipulative therapy in patients with subacromial impingement syndrome: A randomized controlled study

BACKGROUND Thoracic SMT can improve symptoms in patients with subacromial impingement syndrome. However, at this time the mechanisms of SMT are not well established. It is possible that changes in pain sensitivity may occur following SMT. OBJECTIVES To assess the immediate pain response in patients with shoulder pain following thoracic spinal manipulative therapy (SMT) using pressure pain threshold (PPT), and to assess the relationship of change in pain sensitivity to patient-rated outcomes of pain and function following treatment. DESIGN Randomized Controlled Study. METHODS Subjects with unilateral subacromial impingement syndrome (n = 45) were randomly assigned to receive treatment with thoracic SMT or sham thoracic SMT. PPT was measured at the painful shoulder (deltoid) and unaffected regions (contralateral deltoid and bilateral lower trapezius areas) immediately pre- and post-treatment. Patient-rated outcomes were pain (numeric pain rating scale - NPRS), function (Pennsylvania Shoulder Score - Penn), and global rating of change (GROC). RESULTS There were no significant differences between groups in pre-to post-treatment changes in PPT (p ≥ 0.583) nor were there significant changes in PPT within either group (p ≥ 0.372) following treatment. NPRS, Penn and GROC improved across both groups (p < 0.001), but there were no differences between the groups (p ≥ 0.574). CONCLUSION There were no differences in pressure pain sensitivity between participants receiving thoracic SMT versus sham thoracic SMT. Both groups had improved patient-rated pain and function within 24-48 h of treatment, but there was no difference in outcomes between the groups.

Overestimation of aerobic capacity with the bruce treadmill protocol in patients being assessed for suspected myocardial ischemia.

INTRODUCTION Peak oxygen uptake (VO₂) is prognostic for morbidity and mortality. Estimating aerobic capacity during traditional exercise stress testing is common as it has been shown that total treadmill time on the Bruce protocol predicts peak VO₂. However, the potential to overestimate peak VO2 exists and may have clinical implications regarding the interpretation of exercise test data. METHODS Subjects (N = 303) with symptoms suggestive of myocardial ischemia underwent a myocardial perfusion study and an exercise test with simultaneous ventilatory expired gas analysis. Estimated peak VO₂ from the Bruce treadmill protocol was compared with measured peak VO₂. The Duke Treadmill Score (DTS) was calculated with treadmill time (DTS(time)) and also with measured VO₂ (DTS(measured)),expressed as metabolic equivalents (METs), and converted to time. RESULTS Peak measured METs was significantly lower than peak estimated METs in the entire cohort (6.5 ± 1.9 vs 8.8 ± 2.8, P < .001) as well as in female (5.7 ± 1.4 and 7.8 ± 2.1, P < .001) and male (7.3 ± 2.0 and 9.7 ± 3.1, P < .001) subgroups. Calculation of the DTS with measured METs resulted in a significantly lower score compared with its calculation with treadmill time (2.7 ± 3.5 vs 5.8 ± 4.6, P < .001). Receiver operating characteristic curve analysis revealed that DTS(measured) produce a statistically significant model for diagnosing a perfusion defect in both men and women (P < .05), whereas DTS(time) was diagnostic only in men (P < .05). DISCUSSION This study demonstrates that estimates of aerobic capacity are significantly higher than measured values and this difference may result in a significant underestimation of morbidity/mortality risk.

The Clinical Utility of Cardiopulmonary Exercise Testing in Suspected or Confirmed Myocardial Ischemia

Heart disease is a major cause of morbidity and mortality in the United States, with coronary artery disease (CAD) representing more than half of all cardiovascular events. Stable patients presenting with symptoms suggestive of CAD are likely to undergo an exercise electrocardiogram (ECG) and/ or imaging study as a first-line diagnostic assessment. A cardiopulmonary exercise test (CPX) is an ECG stress test plus ventilatory gas analysis. Recently, CPX has been used to detect exercise-induced myocardial ischemia (EIMI) suggestive of underlying CAD. Two CPX variables, oxygen pulse (VO2/HR) and the slope of oxygen consumption versus work rate (ΔVO2/ ΔWR), have been identified to be especially indicative of EIMI. Currently, there are a number of diagnostic tests available for the identification of CAD, with the most widely used being stress ECG, stress myocardial perfusion imaging (MPI) and echocardiography, and cardiac catheterization. Exercise ECG, although inexpensive, has a number of well-recognized limitations, including low sensitivity resulting in false-negative results. Stress (exercise or pharmaceutically induced) MPI and catheterization are more accurate but also more invasive and expensive. It appears that CPX may improve the diagnostic accuracy of exercise ECG. This review will address the potential utility of CPX in patients with suspected or confirmed myocardial ischemia.

Thoracic Spine Manipulation in Individuals With Subacromial Impingement Syndrome Does Not Immediately Alter Thoracic Spine Kinematics, Thoracic Excursion, or Scapular Kinematics: A Randomized Controlled Trial

STUDY DESIGN Randomized controlled trial. OBJECTIVES To determine if thoracic spinal manipulative therapy (SMT) alters thoracic kinematics, thoracic excursion, and scapular kinematics compared to a sham SMT in individuals with subacromial impingement syndrome, and also to compare changes in patient-reported outcomes between treatment groups. BACKGROUND Prior studies indicate that thoracic SMT can improve pain and disability in individuals with subacromial impingment syndrome. However, the mechanisms underlying these benefits are not well understood. METHODS Participants with shoulder impingement symptoms (n = 52) were randomly assigned to receive a single session of thoracic SMT or sham SMT. Thoracic and scapular kinematics during active arm elevation and overall thoracic excursion were measured before and after the intervention. Patient-reported outcomes measured were pain (numeric pain-rating scale), function (Penn Shoulder Score), and global rating of change. RESULTS Following the intervention, there were no significant differences in changes between groups for thoracic kinematics or excursion, scapular kinematics, and patient-reported outcomes (P>.05). Both groups showed an increase in scapular internal rotation during arm raising (mean, 0.9°; 95% confidence interval [CI]: 0.3°, 1.6°; P = .003) and lowering (0.8°; 95% CI: 0.0°, 1.5°; P = .041), as well as improved pain reported on the numeric pain-rating scale (1.2 points; 95% CI: 0.3, 1.8; P<.001) and function on the Penn Shoulder Score (9.1 points; 95% CI: 6.5, 11.7; P<.001). CONCLUSION Thoracic spine extension and excursion did not change significantly following thoracic SMT. There were small but likely not clinically meaningful changes in scapular internal rotation in both groups. Patient-reported pain and function improved in both groups; however, there were no significant differences in the changes between the SMT and the sham SMT groups. Overall, patient-reported outcomes improved in both groups without meaningful changes to thoracic or scapular motion. LEVEL OF EVIDENCE Therapy, level 1b-.