Keller RA, De Giacomo AF, Neumann JA, Limpisvasti O, Tibone JE. Glenohumeral internal rotation deficit and risk of upper extremity injury in overhead athletes: A meta-analysis and systematic review. Sport Heal A Multidiscip Approach. 2018; Online:1-8. doi:10.1177/1941738118756577.
Baseball pitcher’s dominant shoulder, when compared with the non-dominant shoulder, develops decreased internal rotation (IR), known as glenohumeral internal rotation deficit (GIRD). GIRD has been defined as a 20° or greater loss of IR in the throwing shoulder compared with the non-throwing shoulder1. GIRD is believed to be a chronic adaptation that leads to an increased risk of injury in the dominant shoulder or elbow.
The purpose of this systematic review was to investigate the relationship between glenohumeral range of motion (ROM) in overhead athletes and injuries of the upper extremity, specifically in the shoulder or elbow.
A systematic review of primary studies published in English through May 2016 was conducted using PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. All studies that followed a cohort of athletes to determine GIRD’s associaiton with injury were eligible for inclusion. The primary outcome was any upper extremity injury, including shoulder or elbow pain or injury. Two independent reviewers assessed the methodological quality of the studies included. Seventeen studies were included in the systematic review and 10 studies were included in the final meta-analysis.
- Shoulders with GIRD showed a non-statistically significant correlation for shoulder and elbow injury, with a mean difference of 3.11° (95% CI, –0.13° to 6.36°; P = 0.06).
- Total ROM loss favored injury but this was not significant, with a mean difference of 1.95° (95% CI, –0.65° to 4.55°; P = 0.14).
- Shoulder ER gain favored shoulder or elbow injury but this not significant (P = 0.07).
- There were no differences found for ROM between studies with participants younger than or older than 18 years of age.
- The effect of humeral retroversion on the development of GIRD and upper extremity injuries was not investigated.
- Findings related to ROM differences between sides were small and may be within the error of measurement.
- No primary study randomized research participants.
- Seven studies could not be used in the pooled analysis.
- Follow-up duration was inconsistent between studies which could impact the pooled injury rates.
Practical Implications & Additional Thoughts
GIRD has been theorized to contribute to both shoulder and elbow injury in baseball pitchers. The results of this meta-analysis favored an association between injury and GIRD, total ROM loss, and external ROM gain. However, none of these factors showed a significant correlation with an injury of the upper extremity in overhead athletes. These results are somewhat surprising given the amount of attention GIRD has received in the literature over the last 15-20 years.
This systematic review and meta-analysis does not strongly support the theoretical association between GIRD and upper extremity injury risk. There are likely more important risk factors to consider such as those related to pitching volume, mechanics, developmental factors, and other musculoskeletal impairments (i.e., muscular strength).
Manual therapy and stretching exercise have been shown to positively influence ROM deficits in baseball players2. However, it is unclear if such improvements in ROM will result in reduced risk of upper extremity injury. Baseball players should seek to maintain shoulder ROM during the course of a competitive season. However, maintaining muscular strength of the upper and lower body may be more beneficial for reducing injury risk over the long-term.
- Wilk KE, Macrina LC, Fleisig GS, et al. Correlation of glenohumeral internal rotation deficit and total rotational motion to shoulder injuries in professional baseball pitchers. Am J Sports Med. 2011;39(2):329-335. doi:10.1177/0363546510384223.
- Bailey LB, Thigpen CA, Hawkins RJ, Beattie PF, Shanley E. Effectiveness of manual therapy and stretching for baseball players with shoulder range of motion deficits. Sport Heal A Multidiscip Approach. 2017;9(3):230-237. doi:10.1177/1941738117702835.