Journal Club December 2015: The relationship between glenohumeral joint total rotational range of motion and the functional movement screen shoulder mobility test

Article title: The relationship between glenohumeral joint total rotational range of motion and the functional movement screen shoulder mobility test

Author: Sprague, Mokha, Gatens, Rodriguez

Journal: The International Journal of Sports Physical Therapy, 2014

Discussion:

Competitive overhead athletes, such as those participating in baseball, swimming, softball, volleyball, and tennis just to name a few, tend to have upper extremity injuries due to their musculoskeletal development when training for their sport. Specifically, differences in the dominant versus non-dominant rotation of the glenohumeral (GH) joint have been associated with injuries in past studies.

This article discusses tools to assess the GH joint rotation, specifically the relationship between the 1) Functional Movement Screen (FMS) shoulder mobility test versus 2) the passive GH joint total rotational range of motion (TRROM). The article provides pictures of the two screening tests (Figures 1 and 2).  Pages 3 and 4 of Cook, et al is a supplemental attachment that provides greater detail about the shoulder mobility test, which is one of seven moves of the FMS developed by Gray Cook, PT, OCS. The TRROM is the total arc of external rotation plus internal rotation and is measured by a bubble goniometer.

The authors hypothesize that there is no relationship with the findings between these two tests when assessing the mobility of the GH joint in subjects.

The shoulder mobility test and the TRROM were measured during pre-participation examination in 114 NCAA Division II male and female athletes (male = 57, female = 57). The sports represented were baseball and swimming for male subjects and swimming, softball, volleyball, and tennis for female subjects.  For measurement consistency, each participant was asked to not complete physical activity before examination, in which both the shoulder mobility test or the TRROM were performed during one visit in a random order.

An athletic trainer certified in FMS testing completed all of the FMS shoulder mobility tests.  The subject is asked to reach one arm overhead and down their thoracic region and the other behind and up their back as shown in figure 1. A distance between hands less than measured hand length is a score of 3; a distance between one hand length and 1.5 hand lengths is a score of 2; a distance greater than 1.5 hand lengths is a score of 1. A score of zero is given if pain is felt during the test. Scores that are unequal between right and left represent asymmetry in the FMS. Subjects were either “symmetrical” or “asymmetrical” for FMS.

The TRROM was measured by two of the same authors of the study for all subjects shown in figure 2. Internal and external rotation was performed by examiner one (PS) in all subjects. Examiner one had 21 years of experience in orthopedic physical therapy practice. All goniometer measurements were performed by examiner two (RR), with five years of experience as a certified athletic trainer for collegiate and professional athletes. A side-to-side difference of greater than 10 percent was used to define asymmetry for TRROM.

Table 2 shows the results of symmetry vs. asymmetry in the FMS shoulder mobility test and symmetry vs. asymmetry of the TTROM. 40/114 (35.1%) athletes had asymmetries in total GH rotation. 45/114  (39.5%) athletes had asymmetries in the shoulder mobility test. Out of those 45 subjects with asymmetry in the shoulder mobility test, only 17 of them have GH joint rotation differences of greater than 10 degrees.  A Pearson Chi-square analysis (P<.05) was used to compare the presence or absence of asymmetries in FMS shoulder mobility test and TRROM in each subject tested. According to statistical analyses, the authors’ initial hypothesis was correct: athletes with asymmetrical GH joint rotation were not any more likely to have asymmetries in the shoulder mobility test.

10 degrees was chosen to be the threshold of asymmetry due to three reasons: 1) previous results in the literature defining normal asymmetry amounts 2) the amounts of rotation associated with bony morphological changes in overhead athletes and 3) standard goniometry measurement error and the use of a bubble goniometer specifically.  In fact, a TRROM deficit of greater than 5 degrees in overhead athletes has a clinical term: pathologic glenohumeral internal rotation deficit, or p-GIRD. The authors chose 10 degrees or greater to determine TRROM asymmetry to allow for measurement error.

There are several limitations to this study. First, the study did not address small yet clinically significant degree differences or large degree differences that define negatively excessive mobility. Specifically, p-GIRD is a small degree difference that is not detectable using the FMS shoulder mobility test.  Regarding excessive mobility, TRROM greater than 176 degrees have been reported to have an increased incidence of injuries. This study only defines injury with differences between function of non-dominant and dominant GH joints. Second, the study does not address the fact that poor performance on the FMS shoulder mobility test might suggest other underlying problems other than the GH joint. For example, thoracic extension mobility limitation or tissue extensibility dysfunction of the scapula can be some confounding causes of poor performance on the FMS shoulder mobility test.

In conclusion, due to the lack of association between the FMS shoulder mobility test and the TRROM, the FMS shoulder mobility test should not be used alone for injury prevention in overhead athletes. Both screening tools are encouraged to be used.

 

Discussion Points:

  1. Describe how to perform the FMS shoulder mobility test.
  2. Describe how to measure the passive TRROM of the GH joint.
  3. What are the limitations of the study?
  4. In your opinion, how, if anything, should overhead athletes be screened to prevent upper extremity injuries?

LEARN MORE by downloading the article and discussion below:

Article - Link to Full Article

Discussion - AOCPMR Journal Club - Sports Med Dec 2015

Supplemental - Cook2014IJSPT       Cook2014IJSPT.2