The scapula must be directly visualized during the examination. One common mistake is failure to visually inspect the scapula position at rest from the posterior view (Fig. 4.2). This must be done in order to comprehensively evaluate a patient with shoulder pain. Visual observations of the scapula at rest as part of a typical postural evaluation must take into consideration the cranial and spinal alignment issues. Initial visual observation for spinal scoliosis and kyphosis should be routinely performed as these can be underlying biomechanical sources altering scapular mechanics and producing apparent scapular dyskinesis [21, 22].

Many authors have suggested that forward head posture and increased thoracic kyphosis may contribute to scapular protraction and lead to adaptive shortening of postural muscles or muscular strength imbalances [23–26]. A protracted scapular position may be associated with a narrowed subacromial space [27, 28] and a flexed thoracic spine, and forward shoulder position alters scapular motion and results in diminished force output with elevation (Fig. 4.3) [23, 29].

Static assessment of scapular malposition has been demonstrated to be present in patient with and without shoulder pathology [6]. Warner used an enhanced visual observation using Moire’ topography in patients with rotator cuff impingement, shoulder instability, and healthy cohort. Between 30 and 50% of 29 patients with shoulder pathology were found to have static scapular malposition when holding a 4.5 kg weight in hand with elbows flexed to 90° [6]. It is important to note that 3 of 22 or 14% of non-injured healthy cohort had asymmetric scapular position. This is an important point to remember in evaluating the scapula that asymmetric position does not necessarily indicate pathology.

The lateral scapular slide test is a static measurement of the side-to-side difference of the distance from the inferior angle of the scapula to the adjacent spinous process [30]. The measures are performed with the arms in three different positions, arms at the side, hands on hips, and arms abducted to 90° in maximal internal rotation. A side-to-side difference of >1.5 cm is considered pathological. This test has demonstrated fair to moderate levels of reliability and is easily applied in a clinical setting [30, 31]. However, the validity of this test has been questioned because of the findings that both symptomatic and asymptomatic individuals will demonstrate asymmetry when measured in this manner [32, 33]. Additionally, it is possible to have symmetrical pathologic dyskinesis; therefore, validity is questionable when comparison is made only to the contralateral side. Furthermore, the static and two-dimensional nature of this test fails to fully assess the dynamic three-dimensional motion found to occur with scapular movement [10, 32, 34]. This inadequacy of measurement along with questionable validity of results requires the use of other methods of scapular assessment during clinical examination.

Visual assessment schemes for classifying scapular dyskinesis have been developed in an attempt to resolve the issues with linear or static measures [15, 34, 35]. These methods involve classifying scapular movement during shoulder motion into normal or abnormal categories. These measures are considered more functional in application and more inclusive with the ability to judge scapular movement in three-dimensional patterns. Kibler et al. [15] were the first to describe a visually based system for rating scapular dysfunction that defined three different types of motion abnormality and one normal type. Reliability values for this system were too low to support clinical use, and the test was subsequently refined in two studies using a simplified method of classification [35].

The scapular dyskinesis test is a visually based test for scapular dyskinesis that involves a subject performing weighted shoulder flexion and abduction movements, while visual observation of the scapula is performed [34]. This test consists of characterizing scapular dyskinesis as absent or present, and each side is rated separately. Dyskinesis is defined as the presence of either winging (prominence of any portion of the medial scapular border or inferior angle away from the thorax) or dysrhythmia (premature, or excessive, or stuttering motion during elevation and lowering) (Fig. 4.4). Interrater reliability of this test, after brief standardized online training https://​www.​arcadia.​edu/​college-health-sciences/​departments-faculty/​physical-therapy/​shoulder-research-center, has been shown to be better than other previously described visual classification systems. Concurrent validity was assessed in a large group of overhead athletes, and it was shown that those judged as demonstrating abnormal motion using this system also demonstrated decreased scapular upward rotation, less clavicular elevation, and less clavicular retraction when measured with three-dimensional motion tracking [10]. Abnormalities were far more prevalent during shoulder flexion compared with frontal plane abduction. These results support the assertion that shoulders visually judged as having dyskinesis using this system demonstrate distinct alterations in three-dimensional scapular motion, particularly during flexion. However, while visually observed dyskinesis resulted in an altered three-dimensional motion, subjects with dyskinesis were no more likely to report symptoms during sports [10].

Uhl et al. [35] used essentially the same criteria (winging or dysrhythmia) to classify any subject that demonstrated an abnormality in scapular motion into the “yes” classification, and normal movement was classified as “no.” They studied both symptomatic patients with various soft tissue pathologies as well as an asymptomatic group. The “yes/no” test was found to have superior interrater reliability and demonstrated better specificity and sensitivity values when using asymmetry found with three-dimensional testing as a gold standard [35]. An important finding that was consistent with previous research [10] also demonstrated a higher frequency of dyskinesis during shoulder flexion in patients (54%) compared with asymptomatic subjects (14%), whereas no differences between groups were detected during scapular plane elevation.

Because scapular dyskinesis is a common finding in asymptomatic individuals, a basic problem in evaluation is deciding if the presence of scapular dyskinesis is an important abnormality perpetuating symptoms. The possibility exists that alterations of scapular motion could be compensatory strategies to avoid stress on pain-sensitive tissue. Symptom alteration tests have been developed as a way to infer scapular malposition in driving symptoms by manually redirecting scapular movement during provocation testing. If altering scapular position causes an immediate decrease in symptoms, this provides direct evidence that scapular dyskinesis is a contributing factor to shoulder symptoms in that specific patient. The two main symptom alteration tests are the scapular assistance test [16, 30] and the scapular reposition or retraction test [17, 36].

The scapular assistance test involves manually assisting scapular upward rotation during shoulder elevation and determining this effect on pain (Fig. 4.5) [37]. This test was later modified by Rabin incorporating scapular posterior tilting as well (Fig. 4.6) [16]. A positive test is when pain with elevation is either decreased or abolished during the assisted maneuver. This test has demonstrated acceptable levels of reliability [16], increased subacromial space [38], increased upward rotation, and posterior tilt of the scapula [38].

The scapular retraction test involves manually positioning and stabilizing the entire medial border of the scapula in a retracted position on the thorax [37]. This test was developed to help identify patients in which strength loss in shoulder elevation may be due to a loss of proximal stability of the scapula. The test is performed by asking the patient to retract both shoulder blades, and the examiner stabilizes the medial border of the scapula with their forearm (Fig. 4.7). The test is considered positive when the patient demonstrates a reduction of pain or an increase in shoulder elevation strength when the scapula is stabilized during isometric arm elevation in the scapular plane at 90° [19, 37]. Kibler et al. [36] studied this test in symptomatic and asymptomatic subjects. Their findings demonstrated that there was no change in pain levels, and all subjects demonstrated improved strength output, regardless of symptoms.

The scapular reposition test is a modification of the scapular retraction test that involves emphasizing scapular posterior tilting and external rotation but avoiding full scapular retraction (Fig. 4.8) [17]. This modification was based upon previous investigations that have found a decrease in shoulder elevation strength with maximal active scapular retraction [29]. This test has demonstrated acceptable reliability and when performed on a large group of overhead athletes; roughly half of those with pain (46/98) during impingement testing had reduced pain, and 26% had a substantial increase in isometric elevation strength. Therefore, this test may be helpful at identifying a subset of patients with shoulder pathology that may benefit from interventions designed to improve scapular muscle function.

Once an examiner determines that scapular dyskinesis is present and determines it is a contributing factor to the overall shoulder pathology, examination of the surrounding tissue should be performed to identify those factors that may be responsible for causing the altered scapular motion. Many structures have been implicated as possible contributors to the development of scapular dyskinesis. These include deficits in strength or motor control of scapular stabilizing muscles [17, 18, 30, 39], postural abnormalities [23, 26, 40], and impaired flexibility [13, 41]. Therefore, a comprehensive examination of all of these components is necessary (Fig. 4.1).

Muscle strength of key scapular stabilizers can be assessed using standard positions and procedures described by Kendall et al. [42]. The key muscles to test are the axioscapular muscles [43]. Underlying neurological injury to the long thoracic, spinal accessory, or dorsal scapular nerves should be investigated as potential causes of scapular dyskinesis.

The serratus anterior innervated by the long thoracic nerve has a significant contribution to scapular upward rotation, internal rotation, and clavicular protraction. Assessing the ability to protract the scapula around thorax or hold against a retraction load is necessary to confirm the serratus anterior is functioning correctly. The ability to elevate the arm overhead, specifically in the sagittal plane, and protract the scapula around the thorax while resisting a retraction force will indicate that serratus anterior is functioning correctly (Fig. 4.9). The presence of “winging,” inability to keep the inferior medial border of the scapula stabilized to the thorax, during sagittal plane elevation would suggest the serratus anterior is not functioning well. This could be attributable to poor motor control or also to true muscle weakness associated with disuse or nerve injury. This is an important distinction that may influence intervention strategies. If the winging is due to poor motor control, the patient should be able to quickly correct the problem with appropriate cueing and may also perform normally on a manual muscle test. However, weakness and winging that are not easily corrected and persist during isolated manual muscle testing may indicate underlying neurological deficit of the long thoracic nerve pathology [44].