DOI Number: 10.5958/0973-5674.2019.00119.9 Reliability of a Novel Test for Teres Major Muscle Length Joong-yeol An1, Jong-hyuck Weon2, Do-young Jung3, Moon-Hwan Kim4, In-cheol Jeon5 1Department of KEMA Therapy, Graduate School of Humanities Industry, 2Department of Physical Therapy, College of Tourism & Health Science, 3Department of Physical Therapy, College of Tourism & Health Science; Joongbu University, Geumsan, South Korea, 4Department of Rehabilitation Medicine, Wonju Severance Christian Hospital, Wonju, South Korea, 5Department of Physical Therapy, College of Life & Health Sciences, Hoseo University, Asan, South Korea Abstract This study compared the inter- and intra-rater reliability of two methods for measuring the length of the teres major. The length of the teres major was measured using the active shoulder flexion test, with and without external rotation, and the teres major length test. Each examiner used both methods in a single session. Intra- and inter-rater reliability were assessed using the intra-class correlation coefficient (ICC3,1). The independent t-test was used to compare the teres major lengths of the groups. The intra-rater reliability of the active shoulder flexion test and teres major length test was excellent (ICC3,1 = 0.84 and 0.96, respectively), as was the inter-rater reliability (ICC3,1 = 0.83 and 0.91, respectively). There was a significant difference in teres major length between the normal and shortened groups (150.30° and 134.86°, respectively; p<0.05). Our results suggest that the active shoulder flexion test and teres major length test can be reliably applied to determine the length of the teres major. Keywords: Shoulder dysfunction; Muscle length test; Teres major; Reliability Introduction Trigger points due to TM shortness can be found in the posterior deltoid, long head of the biceps brachii, The teres major (TM) is a shoulder muscle that and dorsal aspect of the forearm; pain is rarely referred originates from the posterior aspect of the inferolateral to the elbow (Travell et al. 1998)7. The TM acts as an corner of the scapula and inserts into the medial aspect internal rotator with the pectoralis major and latissimus of the intertubercular groove of the humerus (Grosclaude dorsi. Frequent, dominant internal rotation, such as 1 et al. 2012) . It is innervated by the lower subscapular when sawing, playing badminton or hockey, or water nerve and supplied by the circumflex scapular artery. skiing, can lead to TM shortness (Grosclaude et al. The main functions of the TM are extension, 2012; Maldjian et al. 2000; Sahrmann, 2002; Takase, 1,8,9,10,11 adduction, and internal rotation at the glenohumeral 2008; Leland et al. 2009) . Research has reported joint (Broome et al. 1971; Beck, 1989) 2,3. The TM is that shortening of the TM must be measured precisely called the “lat’s little helper” because of its synergistic when shoulder flexion is limited and the path of the effect with the latissimus dorsi (Biel, 2005)4. When the instantaneous center of rotation is not maintained in the 9 TM is located in the quadrilateral space, it can cause middle of the glenoid fossa (Sahrmann, 2002) . Various teres syndrome, resulting in paresthesias and pain in techniques have been reported for measuring the length the lateral aspect of the scapula and arm (Kendall et al. of the TM. 5, 6 2005; Cirpar, 2006) . First, the range of motion (ROM) of the TM at the glenohumeral joint can be measured in a supine position with hip and knee flexion to flatten the back (Kendall Corresponding author: et al. 2005; Palmer et al. 1998; Kesh 2014; Peter et 5,12,13,14 Jong-hyuck Weon al. 2006) . However, this technique does not just [email protected] measure the length of the TM; the latissimus dorsi is 202 Indian Journal of Physiotherapy and Occupational Therapy. July-September 2019, Vol. 13, No. 3 included. the same subjects using the same methods. Finally, examiner 1 repeated the measurements. A 3-minute rest Another technique that can selectively measure was allowed between each test, and the two tests were the length of the TM measures increased or decreased performed in random order. The examiners were blinded shoulder flexion while the glenohumeral joint is internally to the results of the other examiner. rotated with scapular fixation after the shoulder is fully flexed in a supine position (Sahrmann, 2002)9. Although Active shoulder flexion with/without external this technique can selectively measure the length of the rotation test TM, it is not precise. The previous study introduced a The ASFT with/without external rotation was different technique that can measure muscle tension recently developed to classify subjects into shortened with external rotation of the glenohumeral joint after and normal groups according to the length of the TM. the shoulder is fully flexed with fixation of the scapular The test was performed in a standing position. The lateral border in a supine position [15]. However, this subject was asked to flex the shoulder with internal technique cannot precisely measure the shortness of (palm-down) and external (palm-up) rotation of the the TM, and its reliability and validity have not been glenohumeral joint while the examiner fixed the subject’s reported. scapula by holding the acromion and inferior angle Clinically, there is no best test for precisely of the scapula to inhibit scapular motion. The subject measuring the length of the TM. Therefore, this study was asked to perform active shoulder flexion without investigated a novel method for the precise, selective elbow flexion or shoulder abduction during the test. The measurement of the length of the TM. We hypothesized examiner ensured that each subject’s shoulder posture that the intra- and inter-rater reliability of the novel was maintained during the test. The subject was asked method would be greater than that of conventional to initiate shoulder flexion on the signal “go”. Then, the methods used to measure the length of the TM. subject was asked to stop shoulder flexion on the signal “stop” when the examiner felt the end of resistance Method around the subject’s scapula. Participants In this position, the research assistant took a This study enrolled 38 healthy students. The photograph using a camera 1 m from the shoulder at the inclusion criteria were: 1) no musculoskeletal or neural height of the subject’s shoulder. The angle between the impairment, 2) no history of surgery or pain in the longitudinal axis of the humerus and vertical line in the shoulder or elbow, and 3) no limitation on active shoulder pictures was analyzed using ImageJ software (National exercise. Table 1 summarizes the general characteristics Institutes of Health, Bethesda, MD, USA) (Clarkson of the subjects. The experimental protocols were 2005) (Fig. 1). Each test was repeated twice. explained in detail to all of the subjects, and provided The difference between shoulder flexion with an informed written consent. This study was formally internal and external rotation of the glenohumeral joint approved by the Institutional Review Board process. was >10° in the shortened group and ≤10° in the normal Experimental procedure group. The active shoulder flexion with/without external Teres major length test rotation test (ASFT) and teres major length test (TMLT) The TMLT was performed in a supine position on a were performed by two physical therapists with 3 years therapy table. Before the examination, 0.5-cm-diameter of clinical experience each, while a research assistant markers were placed on the lateral epicondyle of the took pictures and recorded the data. humerus and central axis of shoulder rotation to measure The examiners were trained in the experimental the angle of shoulder flexion precisely using image methods before the main study began. The subjects analysis. were asked to wear a suitable top to enable exact Photographs were taken and an image analysis was measurements. First, examiner 1 measured the subjects performed to measure the angle of shoulder flexion using both test methods. Then, examiner 2 measured while the examiner passively moved the subject’s arm Indian Journal of Physiotherapy and Occupational Therapy, July-September 2019, Vol. 13, No. 3 203 in external rotation and elbow flexion. The subject’s arm The intraclass correlation coefficient (ICC3,1) was was held parallel to the midline of the body. During the used to evaluate the intra- and inter-rater reliability in TMLT, the examiner fixed the subject’s scapula with his the ASFT with/without external rotation and TMLT. The hand in the midaxillary line. independent t-test was used to compare the measurements obtained from the TMLT in the two groups. SPSS ver. While performing this test, the examiner said “stop” 21.0 (IBM Corp., Armonk, NY, USA) was used for the on feeling the end of resistance during shoulder flexion. statistical analysis. The level of statistical significance The research assistant took a photograph of this position was set at α = 0.05. using a camera at 1 m from the shoulder at the height of the subject’s shoulder. Results The angle between the lateral epicondyle of the The shortened group included 44 shoulders and the humerus and the line extending through the central axis normal group included 32 shoulders. The ICC3,1 for the of shoulder rotation was analyzed using ImageJ (Fig. 2). intra-rater reliability of the ASFT and TMLT was 0.84 and 0.96, respectively, while the respective values for Statistical analysis the inter-rater reliability were 0.83 and 0.91 (Table 2). The difference in shoulder flexion between internal Table 3 shows the mean and standard deviation of and external rotation of the glenohumeral joint was the TMLT in the normal (150.30°) and shorted (134.86°) greater than 10° in the shortened group and less than 10° groups.