Philip McClure

Anatomical and biomechanical mechanisms of subacromial impingement syndrome

Subacromial impingement syndrome is the most common disorder of the shoulder, resulting in functional loss and disability in the patients that it affects. This musculoskeletal disorder affects the structures of the subacromial space, which are the tendons of the rotator cuff and the subacromial bursa. Subacromial impingement syndrome appears to result from a variety of factors. Evidence exists to support the presence of the anatomical factors of inflammation of the tendons and bursa, degeneration of the tendons, weak or dysfunctional rotator cuff musculature, weak or dysfunctional scapular musculature, posterior glenohumeral capsule tightness, postural dysfunctions of the spinal column and scapula and bony or soft tissue abnormalities of the borders of the subacromial outlet. These entities may lead to or cause dysfunctional glenohumeral and scapulothoracic movement patterns. These various mechanisms, singularly or in combination may cause subacromial impingement syndrome.

Analysis of Lumbar Spine and Hip Motion During Forward Bending in Subjects With and Without a History of Low Back Pain

Study Design. This study analyzed two groups of subjects during forward bending. Group 1 (n = 20) contained subjects with a history of low back pain and Group 2 (n = 21) included subjects without a history of low back pain. Objective. The purposes of this study were to establish the amount and pattern of lumbar spine and hip motion during forward bending, and determine differences in motion in subjects with and without a history of low back pain. Summary of Background Data. Reported values for lumbar spine motion during forward bending vary from 23.9° to 60° and hip motion during forward bending ranges from 26° to 66°. There has been no direct study of both lumbar spine and hip motion during forward bending in subjects with and without a history of low back pain to establish differences in total amounts or pattern of lumbar spine and hip motion during forward bending. Methods. A three‐dimensional optoelectric motion analysis system was used to measure the amount and velocity of lumbar spine and hip motion during forward bending. Each subject performed three trials of forward bending that were averaged and used for statistical analysis. Hamstring flexibility was also assessed by two clinical tests, the passive straight leg raising and active knee extension tests. Results. Mean total forward bending for all subjects was 111°: 41.6° from the lumbar spine and 69.4° from the hips. There were no group differences for total amounts of lumbar spine and hip motion or velocity during forward bending. The pattern of motion was described by calculating lumbar‐to‐hip flexion ratios for early (0‐30°), middle (30‐60°), and late (60‐90°) forward bending. For all subjects, mean lumbar‐to‐hip ratios for early, middle, and late forward bending were 1.9, 0.9, and 0.4, respectively. Therefore, the lumbar spine had a greater contribution to early forward bending, the lumbar spine and hips contributed almost equally to middle forward bending, and the hips had a greater contribution to late forward bending. A t test revealed a difference between groups for the pattern of motion. Group 1 tended to move more at their lumbar spine during early forward bending and had a significantly lower lumbar‐to‐hip flexion ratio during middle forward bending (P < 0.01). Hamstring flexibility was strongly correlated to motion in subjects with a history of low back pain, but not in healthy subjects. Conclusions. The results provide quantitative data to guide clinical assessment of forward bending motion. Results also suggest that although people with a history of low back pain have amounts of lumbar spine and hip motion during forward bending similar to those of healthy subjects, the pattern of motion is different. It may be desirable to teach patients with a history of low back pain to use more hip motion during early forward bending, and hamstring stretching may be helpful for encouraging earlier hip motion.

Thoracic position effect on shoulder range of motion, strength, and three-dimensional scapular kinematics☆

OBJECTIVES To determine the effect of thoracic posture on scapular movement patterns, active range of motion (ROM) in scapular plane abduction, and isometric scapular plane abduction muscle force. STUDY DESIGN AND METHOD Repeated measures design. There were 34 healthy subjects (mean age, 30.2 yrs). Each subject was positioned and stabilized while sitting in both erect and slouched trunk postures. In each sitting posture a three-dimensional electromechanical digitizer was used to measure thoracic flexion and scapular position and orientation in three planes. Measurements were taken with the arm (1) at the side, (2) abducted to horizontal in the scapular plane, and (3) at maximum scapular plane abduction. In each posture, isometric abduction muscle force was measured with the arm at the side and abducted to horizontal in the scapular plane. RESULTS In the slouched posture, the scapula was significantly more elevated in the interval between 0 to 90 degrees abduction. In the interval between 90 degrees and maximum abduction, the slouched posture resulted in significantly less scapular posterior tilting. There was significantly less active shoulder abduction ROM in the slouched posture (mean difference = 23.6 degrees +/- 10.7 degrees). Muscle force was not different between slouched and erect postures with the arm at the side, but with the arm horizontal muscle force was decreased 16.2% in the slouched position. CONCLUSION Thoracic spine position significantly affects scapular kinematics during scapular plane abduction, and the slouched posture is associated with decreased muscle force.

A clinical method for identifying scapular dyskinesis, part 2: validity

CONTEXT Shoulder injuries are common in athletes involved in overhead sports, and scapular dyskinesis is believed to be one causative factor in these injuries. Many authors assert that abnormal scapular motion, so-called dyskinesis, is related to shoulder injury, but evidence from 3-dimensional measurement studies regarding this relationship is mixed. Reliable and valid clinical methods for detecting scapular dyskinesis are lacking. OBJECTIVE To determine the interrater reliability of a new test designed to detect abnormal scapular motion. DESIGN Correlation design using ratings from multiple pairs of testers. SETTING University athletic training facilities. PATIENTS OR OTHER PARTICIPANTS A sample of 142 athletes (from National Collegiate Athletic Association Divisions I and III) participating in sports requiring intense overhead arm use. INTERVENTION(S) Participants were videotaped from the posterior aspect while performing 5 repetitions of bilateral, weighted (1.4-kg [3-lb] or 2.3-kg [5-lb]) shoulder flexion and frontal-plane abduction. Videotapes from randomly chosen participants were subsequently viewed and independently rated for the presence of scapular dyskinesis by 6 raters (3 pairs), with each pair rating 30 different participants. Raters were trained to detect scapular dyskinesis using a self-instructional format with standardized operational definitions and videotaped examples of normal and abnormal motion. MAIN OUTCOME MEASURE(S) Scapular dyskinesis was defined as the presence of either winging or dysrhythmia. Right and left sides were rated independently as normal, subtle, or obvious dyskinesis. We calculated percentage of agreement and weighted kappa (kappa(w)) coefficients to determine reliability. RESULTS Percentage of agreement was between 75% and 82%, and kappa(w) ranged from 0.48 to 0.61. CONCLUSIONS The test for scapular dyskinesis showed satisfactory reliability for clinical use in a sample of overhead athletes known to be at increased risk for shoulder symptoms.

Stretching and strengthening exercises: their effect on three-dimensional scapular kinematics.

OBJECTIVE To quantitatively evaluate the effects of commonly used shoulder exercises on shoulder kinematics and resting posture. STUDY DESIGN A repeated-measures design was used with measurements performed before and after a 6-week exercise program. METHOD Twenty asymptomatic subjects with forward shoulder posture were recruited. Stretching exercises for the pectoral muscles and resisted strengthening exercises for the scapular retractors and elevators and the glenohumeral abductors and external rotators were performed three times per week for 6 weeks. A three-dimensional electromechanical digitizer was used to measure thoracic inclination and scapular orientation and position. These measurements were taken with the arm (1) at the side, (2) abducted to 90 degrees, and (3) at maximal abduction. The isometric force of glenohumeral external and internal rotation and horizontal abduction and adduction were measured with a hand-held dynamometer. All subjects were tested before and after the 6-week exercise program. Hotellings T2 and paired t tests were used for data analysis. RESULTS The strength of horizontal abduction and internal and external rotation increased after exercise (p < .01). The anterior inclination of the thoracic spine decreased, and the glenohumeral contribution to arm elevation increased (p < .01). Resting scapular posture did not change. As the arm was abducted to 90 degrees, the scapula showed less upward rotation and less superior translation after the exercise program (p < .01). CONCLUSION The exercise program improved muscle strength, produced a more erect upper trunk posture, increased scapular stability, and altered scapulohumeral rhythm.

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.

Kinematic Analysis of Lumbar and Hip Motion While Rising From a Forward, Flexed Position in Patients With and Without a History of Low Back Pain

Study Design. This study analyzed two groups of individuals during return to an upright position (extension) from a forward, bent position. Group 1 (n = 12) included individuals with a history of low back pain who were currently asymptomatic, and group 2 (n = 12) included individuals with no history of low back pain. Objectives. To determine the amount and pattern of lumbar spine and hip motion that occur as an individual rises from a forward, flexed position, to determine if differences exist in this measurement between individuals with and without a history of low back pain, and to determine if hamstring length is related to the pattern of motion. Summary of Background Data. Reports of interaction between lumbar spine and hip movement vary for forward bending and extension. Differences may be a result of variations in measurement methods, loading conditions, or the pathology present, such as low back pain. Methods. A three‐dimensional optoelectric motion analysis system was used to measure the amount and velocity of lumbar spine and hip motion during extension. Each participant in the study performed three trials of a complete flexion‐extension cycle at a self‐selected speed. The data for the extension portion of the cycle were averaged and used for statistical analysis. Hamstring length also was determined using two clinical tests, the passive straight‐leg raise and the active knee‐extension tests. Results. The pattern of movement was described by calculating lumbar to hip extension ratios for each 25% interval of total extension. Individuals with a history of low back pain tended to move from the lumbar spine earlier than those with no history of low back pain, especially in the initial 25% of the extension motion. For all participants, mean lumbar to hip extension ratios were 0.26 for 0–25% of extension, 0.61 for 25–50%, 0.81 for 50–75%, and 2.3 for 75–100%. The lumbar to hip ratios were different in each 25% interval, demonstrating that the hips had a greater contribution to early extension, with the lumbar spine contribution increasing in the middle intervals and becoming the primary source of motion in the final interval. When lumbar to hip extension ratios were compared with corresponding intervals of flexion, three of four were positively correlated to flexion ratios, demonstrating a reversible lumbopelvic rhythm. Although participants with a history of low back pain had significantly tighter hamstrings than participants with no history of low back pain, hamstring length was not correlated with any of the kinematic characteristics during extension. Conclusions. Participants who were currently asymptomatic but had a history of low back pain moved in a manner similar to that of participants with no history of low back pain except that they demonstrated greater lumbar motion and velocity during the initial phase of extension. This may have been the result of low back pain or a contributing factor in recurrent low back pain.

The influence of different sitting positions on cervical and lumbar posture.

Study Design. This study used a repeated measures design to assess the effects of multiple sitting postures on various spinal angles. All subjects were tested in slouched, erect, forward inclined, and comfortable postures. Objectives. The purposes of this study were to evaluate the changes in head, cervical, lumbar, and pelvic postures in different sitting positions and also to determine if there is a relation between lumbar posture and cervical posture during sitting. Summary of Background Data. Clinicians commonly assert that head and neck position is strongly influenced by lumbar and pelvic position. A biomechanical model was developed that allowed detailed, quantitative description of head, neck, lumbar, and pelvic postures. This model enabled a distinction to be made between upper and lower cervical motions. Methods. Various spinal angles were measured in 30 healthy subjects in four sitting positions using a three‐dimensional digitizing system. Reliability of the measurement procedure was determined using an intraclass correlation coefficient and the values for most angles was above 0.8. Results. With the exception of head orientation, analysis of variance revealed significant differences in spinal angles between different sitting positions. Head orientation appeared to be maintained by compensatory adjustments in both the upper and lower cervical spine and changes in lumbar posture were associated with compensatory changes in overall cervical position. As the lumbar spine moved toward extension, the cervical spine flexed and as the lumbar spine flexed the cervical spine extended. However, there was variation among subjects as to whether cervical spine adjustments occurred primarily in the upper or lower cervical region. Conclusions. Different sitting postures clearly resulted in changes in cervical spine position. Lumbar and pelvic position should be considered when control of cervical posture is desired.

Achilles Pain, Stiffness, and Muscle Power Deficits: Achilles Tendinitis

The Orthopaedic Section of the American Physical Therapy Association presents this sixth set of clinical practice guidelines on Achilles pain, stiffness, and muscle power deficits that are characteristic of Achilles Tendinitis. These clinical practice guidelines are linked to the International Classification of Functioning, Disability, and Health (ICF). The purpose of these practice guidelines is to describe evidence-based orthopaedic physical therapy clinical practice and provide recommendations for (1) examination and diagnostic classification based on body functions and body structures, activity limitations, and participation restrictions, (2) interventions provided by physical therapists, (3) and assessment of outcome for common musculoskeletal disorders. J Orthop Sports Phys Ther 2010:40(9):A1–A26. doi:10.2519/jospt.2010.0305

Shoulder Pain and Mobility Deficits: Adhesive Capsulitis

The Orthopaedic Section of the American Physical Therapy Association (APTA) has an ongoing effort to create evidence-based practice guidelines for orthopaedic physical therapy management of patients with musculoskeletal impairments described in the World Health Organizations International Classification of Functioning, Disability, and Health (ICF). The purpose of these clinical practice guidelines is to describe the peer-reviewed literature and make recommendations related to adhesive capsulitis. J Orthop Sports Phys Ther 2013;43(5):A1–A31. doi:10.2519/jospt.2013.0302