Preseason shoulder range of motion screening and in-season risk of shoulder and elbow injuries in overhead athletes: systematic review and meta-analysis

Loading

  1. http://orcid.org/0000-0002-6384-9605Federico Pozzi1,2,
  2. https://orcid.org/0000-0003-3282-2538Hillary A Plummer3,
  3. Ellen Shanleyfour,
  4. https://orcid.org/0000-0003-2487-1399Charles A Thigpen4,
  5. Chase Bauer5,
  6. https://orcid.org/0000-0001-7785-4221Melissa L Wilson6,
  7. Lori A Michener2
  1. 1 Department of Physical Therapy, University of Florida, Gainesville, Florida, United states
  2. 2 Division of Biokinesiology and Concrete Therapy, University of Southern California, Los Angeles, California, USA
  3. 3 Andrews Research & Education Foundation, Gulf Breeze, Florida, USA
  4. iv ATI Physical Therapy, Greenville, South Carolina, USA
  5. v Western Academy of Health Sciences, Pomona, California, USA
  6. 6 Department of Preventive Medicine, University of Southern California, Los Angeles, California, USA
  1. Correspondence to Dr Federico Pozzi, Section of Physical Therapy, University of Florida, Gainesville, FL 32611, U.s.; fpozzi{at}phhp.ufl.edu

Abstract

Objective To characterise whether preseason screening of shoulder range of movement (ROM) is associated with the risk of shoulder and elbow injuries in overhead athletes.

Pattern Systematic review and meta-analysis.

Data sources Six electronic databases up to 22 September 2018.

Eligibility criteria Inclusion criteria were (1) overhead athletes from Olympic or college sports, (2) preseason measures of shoulder ROM, (3) tracked in-season injuries at the shoulder and elbow, and (4) prospective cohort blueprint. Exclusion criteria were (1) included contact injuries, (2) lower extremity, spine and hand injuries, and (3) total study not published in English.

Results Fifteen studies were identified, and they included 3314 overhead athletes (baseball game (74.half dozen%), softball (iii.1%), handball (16.1%), tennis (2.0%), volleyball (2.0%) and swimming (ii.ii%)). Female person athletes are unrepresented (12% of the overall sample). Report quality ranged from xi to 18 points on a modified Downs and Black checklist (maximum score 21, better quality). In i report, swimmers with low (<93°) or high (>100°) shoulder external rotation were at college risk of injuries. Using information pooled from 3 studies of professional baseball pitchers, we showed in the meta-analysis that shoulder external rotation insufficiency (throwing arm <5° greater than the not-throwing arm) was associated with injury (odds ratio=1.90, 95% confidence interval i.24 to 2.92, p<0.01).

Conclusion Preseason screening of shoulder external rotation ROM may identify professional person baseball game pitchers and swimmers at chance of injury. Shoulder ROM screening may not be effective to identify handball, softball, volleyball and tennis players at chance of injuries. The results of this systematic review and meta-analysis should be interpreted with circumspection due to the express number of studies and their loftier caste of heterogeneity.

PROSPERO registration number CRD42017072895.

  • baseball
  • handball
  • swimming

https://creativecommons.org/licenses/past/4.0/

This is an open up access commodity distributed in accordance with the Artistic Eatables Attribution 4.0 Unported (CC Past 4.0) license, which permits others to copy, redistribute, remix, transform and build upon this work for whatever purpose, provided the original work is properly cited, a link to the licence is given, and indication of whether changes were made. Encounter: https://creativecommons.org/licenses/by/4.0/.

Statistics from Altmetric.com

  • baseball
  • handball
  • swimming

Introduction

Overuse shoulder and elbow injuries are common across unlike overhead athletes regardless of age, sexual activity and level of playing.one–five Evaluating potential environmental-specific (extrinsic) and private-specific (intrinsic) risk factors for shoulder and elbow injuries in overhead athletes is a research priority. Extrinsic risk factors include sport specialisation, training intensity, number of games per week, and number of pitches or throws per game and over a year.6–10 Extrinsic factors may contribute to overuse injuries due to repetitive load on the shoulder and elbow without adequate time to recover. Intrinsic not-modifiable risk factors include historic period, height, sex and previous injury.6 7 Impairments of joint range of movement (ROM) except when attributable to humeral torsion,11–17 strength18 19 and neuromuscular control20 are intrinsic modifiable risk factors because their effect may exist modifiable through targeted injury prevention programmes.21

Changes or side-to-side differences of shoulder ROM consequence from the repetitive demands of overhead sport,22–24 but they may besides be a risk factor for injury. In Keller'south systematic review, injured overhead athletes (baseball, handball and tennis) had deficits of shoulder internal rotation, external rotation and full rotation ROM.16 Limitations included studies with cantankerous-sectional and retrospective designs, and so it is impossible to make up one's mind whether the deficits in ROM were present before the injury or were an accommodation to the injury.16 Using prospective cohort studies, Bullock et al's17 meta-analysis showed that high school baseball players who sustained an in-season shoulder and elbow injuries take less preseason shoulder internal rotation (absolute value: 44°, side-to-side deviation: v°) and total rotation (absolute value 160°, side-to-side difference: 8°) ROM compared with players who did non sustain an injury during the season. Even so, the authors did not report the magnitude of hazard of in-season injuries with an odds or adventure ratio for the players with the defined preseason ROM values.17 Agreement the strength of the association between risk factors (preseason ROM) and outcomes (injury) is critical to evaluate the power of preseason ROM to predict gamble of injury in overhead athletes, and to design screening and prevention programmes.21

The purpose of this systematic review and meta-assay was to summarise the available bear witness, to evaluate the quality of research methods and to characterise the association of preseason shoulder ROM with futurity take chances of shoulder and elbow injuries in prospective cohorts of overhead athletes. We hypothesised that preseason ROM measures of shoulder internal rotation, external rotation, horizontal adduction, shoulder flexion and total rotation have the potential to identify overhead athletes at risk of shoulder and elbow injuries.

Methods

This review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.25 The review protocol was registered on PROSPERO.

Data source and search

The following databases were queried for existing evidence (from their inception to September 2018): MEDLINE, Scopus, Embase, Cochrane Library, Cumulative Index to Nursing and Centrolineal Health Literature and SPORTdiscus (via Ebsco). A full-fourth dimension librarian from the Norris Medical Library of the Academy of Southern California adult and conducted the search strategy for each database. The search strategies used to query MEDLINE and Cochrane Library are reported in online supplementary appendix A and were adapted for the other databases. Three senior authors with expertise in upper extremity injury in overhead athletes (ES, CAT and LAM) reviewed the list of the included studies to place studies that were not found through the systematic search of the databases. Farther, the reference list of the included studies was hand searched for additional missing studies.

Supplemental cloth

Study selection

Identified manufactures were imported in Endnote (Clarivate Analytics, Philadelphia, USA) to screen for duplicates. After, they were exported into Covidence (Covidence systematic review software, Veritas Health Innovation, Melbourne, Australia; available at www.covidence.org) for screening and full-text selection. The following inclusion criteria were used to determine eligibility: (one) inclusion of overhead athletes from Olympic or National Collegiate Athletic Association sanctioned collegiate sports (wide participation), (2) use of preseason measures of ROM; (3) tracked injuries at the shoulder and/or elbow throughout the season, and (iv) utilise of a prospective cohort blueprint. Exclusion criteria included the post-obit: (i) sport does not require overhead repetitive activities; (2) inclusion of contact injuries; (3) lower extremity, spine and mitt injuries; and (4) full report not published in English. Studies that assessed humeral retrotorsion were excluded from this review because this physical impairment is not modifiable.26 27 Studies that assessed the effectiveness of specific interventions to reduce the take chances of shoulder and elbow injuries were excluded from this review.

Two authors (FP and HAP) independently screened the title and abstract to identify relevant studies for the full-text review. A subsample of 100 studies were randomly selected to calculate the agreement between the 2 reviewers (Cohen'southward kappa=0.88, indicating high level of understanding). During both the title and abstruse screening and the full-text review, disagreements between the two authors were starting time discussed. If consensus was not accomplished, a 3rd writer (LAM) was consulted to make the terminal decision regarding inclusion or exclusion.

Assessment of methodological quality

Two authors (PF and HAP) independently scored the methodological quality of each included study using a modified version of the Downs and Black Checklist.28 The Cochrane Handbook recommends the use of this checklist to appraise not-randomised studies.29 The original Downwardly and Black Checklist contains 27 yes/no questions distributed over 5 sections: reporting, external validity, internal validity (bias and selection bias) and ability. Previous systematic reviews that investigated injury risk factors in athletes recommended modifying the Downs and Black Checklist because 6 out of the original 27 questions exercise not apply to prospective cohort studies.20 thirty Further, the score of question number 27 (Did the study accept sufficient power to observe a clinically important upshot where the probability value for a difference being due to hazard is less than v%?) was converted into a dichotomous output (yes=1, the report met the a priori sample target; no=0, the report did non written report or did not meet the a priori sample target). The modified checklist used in this study had a maximum score of 21 points, which indicated higher methodological quality. For each article, the raw score and the percentage score [(raw score/21 possible points)×100] was reported. During the cess of methodological quality, disagreements betwixt the two authors were starting time discussed. If consensus was not achieved, a third author (LAM) was consulted to make the last decision regarding specific scores.

Data extraction

1 author (FP) extracted the data, which was checked for consistency past a second author (HAP). The following data was obtained: (1) author, (2) twelvemonth of publication, (3) sport, (4) study population, (four) sample size, (5) sex, (6) age, (7) participants reporting discomfort or injury at baseline evaluation, (8) participants lost to follow-up, (9) number of participants included in the assay, (10) number of seasons, (eleven) injury definition, (12) injury tracking, (xiii) number of injuries and (14) number of injured participants.

Outcome measures

Injury

An injury was defined as any shoulder-related or elbow-related complaint incurred due to competition or training.31 Injuries to the shoulder and elbow had to be tracked during the season by healthcare personnel, in-season player interview or self-reported questionnaires.

Range of motion

ROM testing procedures, the direction of ROM testing and the side tested were recorded. ROM measurements included two types of variables: (one) absolute ROM of the throwing arm and (2) ROM of the throwing arm expressed as a function of the ROM of the non-throwing arm. The latter oftentimes includes a specific ROM cut-off to define the absence or presence of a specific ROM arrears. The type of ROM measure and the cut-off used to identify ROM deficit were extracted for the analysis.

Information analysis

Only ROM variables that were included as predictors in at least iii studies were considered for the meta-analysis. For the studies included in the meta-analysis, odds or risk ratios, confidence intervals and p values were extracted. A random-effect meta-analysis was conducted using the method of Mantel-Haenszel stratified by the direction of ROM and the type of measurement (absolute and deficit). The primary event was shoulder and elbow injuries. For all ROM measurements, except for shoulder internal rotation difference, the summarised effect estimate was the odds ratios. For shoulder internal rotation difference, Shanley et al 12 reported the adventure ratio as effect estimate, while Wilk et al 32 33 reported the odds ratio. In club to synthesise the information between these studies12 32 33 and to provide an overall judge, crude odds ratios were converted to rough chance ratios using the formula

Embedded Image

where RR is the risk ratio; OR is the odds ratio; and R0 is equal to the risk of a positive outcome in the unexposed grouping. Summary outcome estimates and 95% confidence intervals were reported.

Iii statistic assessed the heterogeneity of each ROM meta-analysis. Funnel plot and Egger'due south examination evaluated publication bias and the possibility of a small study event.

Results

Study option

The database search was completed on 22 September 2018. The search identified x 539 studies (figure 1): 2855 duplicates were removed; 7684 studies were screened; and 93 studies were reviewed in full text. Fifteen studies11–15 32–41 met the inclusion and exclusion criteria and were included.

Study characteristics

Table 1 summarises the characteristics of the included studies. A total of 3314 (female=385) athletes of overhead sports were included in this review, specifically, baseball game (northward=2471, female person=27), softball (n=103, all female person), handball (north=535, female=161), tennis (n=65, female=25), volleyball (n=66, female person=32) and swimming (n=74, female=37). Six studies included samples of both female and male athletes,12–14 34 39 xl only merely one considered sex activity every bit a covariate in the analysis.39 I study12 included a cohort of baseball and softball players but reported contained analyses for each sport. One study35 included a cohort of youth and adolescent baseball pitchers just reported independent analyses for each age group. A group of authors reported information from the aforementioned cohort in two different manuscripts, i that analysed risk factors for shoulder32 and ane for elbow injuries.33 Nearly of the studies followed upwards athletes for one competitive flavor. Nine studies tracked injuries beyond multiple seasons (range of two to eight seasons).eleven 32 33 35 37 38 40 41 Athletes were re-evaluated at the beginning of each flavour in seven studies,eleven 32 33 35 37 38 41 while one considered injuries occurring over a 2-year span.twoscore After accounting for athletes evaluated for multiple seasons and lost to follow-up, the total included sample was 3750, specifically baseball (north=3026), softball (northward=103), handball (northward=428), lawn tennis (n=55), volleyball (n=64) and swimming (n=74).

View this table:

  • View inline

Table 1

Study characteristics

Injury definition varied across studies (table 1). The cumulative shoulder and elbow injury rate in the overall sample of overhead athletes was 17% (666/3750). Divided past sport, the cumulative shoulder and elbow injury rate was 14% (431/3026) for baseball,11 12 32–38 41 nine% (nine/103) for softball,12 43% (182/428) for handball,fifteen 39 44% (24/55) for tennis,40 4% (iii/64) for volleyball14 and 23% (17/74) for swimming.13

Risk of bias

The average score on the modified Downs and Black Checklist was 14.9%±2.i% (range 11–18, online supplementary appendix B). 6 studies achieved a score of at to the lowest degree 16, which is greater than 75%.eleven thirteen 15 34 36 39

Supplemental fabric

ROM measurements

Shoulder ROM directions included flexion, internal and external rotation, and horizontal adduction. Shoulder flexion ROM was measured using a standard goniometer with participants supine, and this methodology was consistent across studies.xi 32 33 40 Shoulder internal and external rotation ROMs were measured either with a goniometer11 12 14 32 33 38 or a digital inclinometer13 15 35–37 39 41 with participants supine with shoulder abducted at ninety° and elbow flexed at 90°. Horizontal adduction ROM was measured with either a goniometer11 12 34 or a digital inclinometer35 37 41 with participants supine, according to the procedure described by Laudner et al.42 Farther, nine studies11 12 15 32–34 36–39 41 calculated the total rotation of movement by summing internal and external ROMs.

Preseason screening and in-season shoulder and elbow injuries

Methodological differences prevented including the results of 8 studies in the meta-assay.13 xiv 34 37 38 40 41 43 Three studies32 33 38 from the aforementioned group of investigators had overlapping data drove fourth dimension frames: three competitive seasons, from 2005 to 2008,38 and eight competitive seasons, from 2005 to 2012.32 33 But the data from the eight competitive seasons were included in the meta-analysis.32 33 Softball players were excluded from the internal rotation deficit meta-analysis because none of the ix softball players with at to the lowest degree 20° of shoulder internal rotation deficit sustained an injury.12 Tabular array ii summarises the results excluded from the meta-analysis. Shanley et al 35 used a receiver operating characteristics curve to summate the preseason cut-off of shoulder ROM deficit with the highest sensitivity for run a risk of shoulder and elbow injuries. In adolescent baseball pitchers, a shoulder internal rotation deficit of at least 13° and a shoulder horizontal adduction deficit of at least 15° were associated with a v.eight and 4.1 greater risks of shoulder and elbow injuries.35 The same assay did not produce any significant results in youth baseball game pitchers.35 Shanley et al 12 reported that high school baseball players with arrears of shoulder internal rotation ROM greater than 25° are at college hazard (run a risk ratio=4.viii) of injury. In contrast, Tyler et al 37 reported that high school pitchers with no internal rotation deficit (side-to-side difference of less than 0°) are at higher risk of shoulder and elbow injuries (hazard ratio=4.ix) compared with pitchers with a loss of internal rotation of at least 20°. Walker et al thirteen reported that swimmers with low (<93°) and high (>100°) absolute shoulder external rotations are at adventure of a shoulder injury (odds ratios=24.9 and 23.0, respectively) compared with swimmers with shoulder external rotation within 93° and 100°. The odds ratios increased to 32.5 (external rotation <93°) and 35.four (external rotation >100°) when the statistical model included swimming preparation distance. Prospective studies in softball,12 tennis40 and volleyball14 players showed that preseason shoulder ROM is non associated with in-flavor shoulder and elbow injuries.

View this table:

  • View inline

Tabular array 2

Summary of the results from the report that were non included in the meta-assay

Meta-analyses included information from prospective cohorts of baseball and handball players.11 12 fifteen 32 33 36 39 Two studies reported effect estimates that were adjusted based on baseline characteristics (detailed information reported in figure 2).15 39 Independent meta-analysis evaluated absolute shoulder ROM of external rotation,15 36 39 internal rotation15 36 39 and full rotation.15 36 39 Other studies measured the accented value of internal and external rotations,13 xiv xl 41 as well as total rotation,34 41 but the methodological differences13 41 in the predictive analysis or incomplete results reporting14 xl prevented from including these studies in the corresponding meta-analysis. Only one study measured the absolute value of shoulder flexion and shoulder horizontal adduction.11 The results of the meta-analyses indicated that absolute shoulder ROM is not associated with shoulder and elbow injuries (figure two). A large degree of heterogeneity between studies was found for the absolute value of absolute shoulder internal rotation (Itwo=71.9%, p=0.03) and total rotation (Iii=62.1%, p=0.07) ROMs.

Figure 2

  • Download figure
  • Open in new tab
  • Download powerpoint

Effigy 2

Wood plot indicating the meta-analysis results for all preseason ROM screening and subsequent run a risk of shoulder and elbow injuries. The summarised effect estimate was the odds ratios for absolute external, internal and full rotation and external and flexion arrears. The summarised effect estimate for internal rotation deficit was the risk ratio. a, adjusted for history of shoulder surgery. b, adjusted for sex activity and history of shoulder pain during the last flavour. c, adjusted for sexual practice and shoulder pain at baseline. d, adjusted for player position (back actor) and history of shoulder surgery. e, authors reported poor inter-rater and intrarater reliabilities of ROM measurements. CI, confidence interval; OR, odds ratio; ROM, range of motion; RR, risk ratio.

Independent meta-analyses evaluated shoulder flexion,eleven 32 33 external rotation11 32 33 and internal rotation ROM differences.12 32 33 Other studies measured external rotation differences34 36 37 41 and internal rotation differences,34–37 41 but methodological disparities in the predictive assay,37 41 exclusion from multivariate predictive analysis34 and unlike bending cutoffs used to define ROM deficits35 36 prevented from including these studies in the respective meta-analyses. Shoulder full rotation and horizontal adduction ROM differences were measured in seven12 32 33 36–38 41 and four11 12 34 35 studies, respectively. However, the methodological differences in the predictive analysis,37 41 the unlike cut-offs used to define shoulder total rotation or horizontal adduction arrears,11 12 32 33 35 36 38 and exclusion from multivariate predictive analysis,34 prevented combining the information in meta-analyses. 3 side-to-side ROM cutting-offs were consistently used across studies to define specific ROM deficits: (1) shoulder flexion: non-throwing arm–throwing arm >five°xi 32 33; (two) shoulder external rotation: throwing arm–non-throwing arm >v°eleven 32 33 and (3) shoulder internal rotation: non-throwing arm–throwing arm >20°.12 32 33 The results of the meta-analyses indicated that the presence of a v° insufficiency of shoulder external rotation between the throwing and the non-throwing artillery (ie, external rotation in the throwing arm was <v° greater than the not-throwing arm) is significantly associated with in-season shoulder and elbow injuries (odds ratio=i.xc, 95% confidence interval one.24 to 2.92, p<0.01; figure 2). The issue estimates of the meta-analysis for external rotation insufficiency did non have substantial heterogeneity (I2=0%, p=0.50). In contrast, a large caste of heterogeneity between studies was found for shoulder flexion difference (I2=71.four%, p=0.03).

Overall, the funnel plot was fairly symmetrical and independent inside the borders of the funnel, indicating express publication bias (effigy 3). However, there is some evidence of publication bias for external rotation ROM deficit. The funnel plot positive disproportion suggests that negative or null studies are missing from the published literature. Last, at that place was no evidence of minor study bias (p=0.35).

Figure 3

  • Download figure
  • Open in new tab
  • Download powerpoint

Figure 3

Overall, the plot indicates that all reported studies lie within the 95% confidence limits, suggesting limited reporting bias. The proximity of almost studies to the solid blackness line indicates the nil results observed in the bulk of included studies. Some asymmetry is noted, especially for external rotation deficit, indicating likely reporting bias for this exposure.

Word

This systematic review summarised the available evidence, evaluated methodological quality and analysed whether preseason screening of shoulder ROM is associated with the risk of shoulder and elbow injuries in overhead athletes. Overall, we identified 15 prospective accomplice studies,11–15 32–41 with the majority focusing on baseball. Limited evidence was bachelor for other overhead sports, such as handball, softball, volleyball, swimming and tennis. Female person athletes are under-represented, accounting for 12% of the overall sample (34% afterwards removing studies on baseball, which is a male-predominant sports). Only one prospective cohort written report of a female person-predominant sport of softball12 was identified for this review. Our overall hypothesis that preseason shoulder ROM beyond all overhead athletes identifies those at adventure for upper extremity injuries was not confirmed. Summarising the evidence for the meta-assay was challenging due to the methodological differences betwixt studies. The meta-analysis included iii shoulder accented ROM variables (external, internal and full rotations) and three shoulder ROM deficit (flexion, internal rotation and external rotation). The results of the meta-assay indicated that professional baseball game pitchers were at higher take a chance of shoulder and elbow injuries when the throwing arm external rotation was not at least 5° greater than the non-throwing arm. Therefore, screening shoulder external rotation ROM may be valuable in professional baseball game pitchers.

Run a risk of bias

Four studies failed to outline the inclusion and exclusion criteria used to select their sample.32 33 37 41 The number of the athletes who were lost to follow-upward was clearly described in three studies,xiii 34 39 and five studies reported both the number of athletes that were approached and the number of athletes who agreed to participate.15 34 36 39 xl Therefore, some of the included studies may endure from selection bias. The investigator responsible for preseason measurements was blinded for mitt authorisation in three studies,12 35 36 exposing the remaining studies to potential investigator bias. Simply five studies adjusted the analysis for potential confounders.xi 13 fifteen 32 39 3 studies calculated the required sample size a priori12 34 36: 2 studies met their target sample size34 36; ane study recruited 82% of the estimated sample due to limited fourth dimension to perform preseason screening.12 Therefore, the majority of the studies may lack sufficient sample size. 3 studies did not report the investigator reliability in collecting shoulder ROM.eleven 34 37 Andersson et al 39 reported poor inter-rater and intrarater reliabilities for their ROM measurements, which are a critical threat to internal validity that tin can bias their results.

Baseball

The gamble of shoulder or elbow injuries increased almost twofold if the throwing shoulder of professional baseball game pitchers did not have at least 5° greater external rotation compared with the not-throwing shoulder. It is well accepted that the throwing arm of overhead athletes displays greater external rotation ROM compared with the non-throwing arm.44 45 Greater shoulder external rotation increases the corporeality of motility available to develop ball velocity.46–48 Professional baseball pitchers with less throwing arm external rotation may employ other strategies, such as dropping their arm slot or assuasive their arm to lag behind, to maintain throwing performance, which may place them at higher take a chance of injury.49 50 The fact that less throwing arm shoulder external rotation was associated with shoulder or elbow injury in two independent cohorts of professional person baseball pitchers farther corroborates the value of screening external rotation ROM in this population.11 21 32 The ultimate goal of athlete screening is to reduce their take a chance of injury past intervening on modifiable risk factors.21 Therefore, randomised clinical trials that compare the efficacy of the screening and intervention plan compared with usual training and prevention programmes only are necessary to fully empathize the value of screening for shoulder external rotation deficit in professional baseball game pitchers.

In contrast, younger baseball pitchers and position players (age vii–18 years) exercise non consistently brandish differences in shoulder external rotation in the throwing arm compared with the non-throwing arm.51 Although non included in the meta-assay, four studies34 36 37 41 failed to find a positive association betwixt shoulder external rotation difference and subsequent risk of shoulder or elbow injuries in cohorts of junior and loftier-schoolhouse baseball players. Bullock et al 17 found no absolute differences of preseason shoulder external rotation ROM between a group of high school baseball game players who suffered an in-season shoulder or elbow injury and a group who did non. Accommodation of shoulder external rotation ROM may occur over several years of playing and with increased level of performance, which may explain the findings in younger cohorts.

The current meta-analysis indicates that a shoulder internal rotation difference of at least 20° between the throwing and the non-throwing arms is non associated with future shoulder and elbow injuries. The heterogeneity of the studies included in the meta-analysis, which combined professional baseball game pitchers32 33 and high schoolhouse baseball players (position players included),12 must exist considered when interpreting these results. Shoulder internal rotation may not be an important risk factor for professional baseball pitchers.11 32 33 In contrast, a contempo meta-assay showed that a preseason side-to-side deviation of at least v° of shoulder internal rotation characterised high school baseball game players that sustained an in-flavour injury.17 Screening for 5° side-to-side deviation in shoulder internal rotation may generate a high number of false positives, considering that previous studies found that only greater internal rotation difference (favouring the not-throwing arm) carried a higher risk of shoulder and elbow injuries (at least of 13°, adolescent pitchers, and at to the lowest degree 25°, high school baseball players; table 2).12 35 Additionally, one written report found that high school baseball pitchers with no shoulder internal rotation deficit in their throwing arm take a higher incidence and a college risk of shoulder and elbow injuries compared with those with at least twenty° of shoulder internal rotation differences between the throwing and non-throwing artillery.37 Thus, unwarranted stretching, which arbitrarily increases the internal rotation on the throwing arm, may also be deleterious for high school baseball players.

A shoulder flexion arrears of at least 5° in the throwing arm is non associated with shoulder and elbow injuries in a homogenous sample of professional person baseball game pitchers. Information technology is important to note that the anatomical location of the injury was different between the studies included in this meta-analysis. 2 studies considered only elbow injuries,11 33 while 1 considered only shoulder injuries.32 Based on the reported OR (figure two), it is unclear why shoulder flexion ROM deficit in the throwing arm would be associated with risk of injury at the elbow, just non at the shoulder. Reduced shoulder flexion may be related to altered latissimus dorsi muscle flexibility. A shoulder flexion deficit of 5° in the throwing arm may result in a lower arm slot during throwing, which has been shown to increase elbow joint stress.52 53 Futurity studies should investigate this potential association.

Bullock et al 17 showed that, when measured at preseason, loftier schoolhouse baseball players that sustained in-flavor shoulder and elbow injuries had at least 8° lower horizontal adduction ROM compared with players who did not get injured.17 When included in hazard analysis, Shanley et al 35 found that high schoolhouse baseball pitchers with a divergence of horizontal adduction of at least 15° between the throwing and non-throwing arms were at four times greater risks of shoulder and elbow injuries. Similar findings were not reported in one accomplice of professional baseball pitchers,11 or in studies including cohorts that combined high schoolhouse baseball game pitchers and position players.12 34 Taken together, these findings may betoken that players' historic period and position should be considered when screening horizontal adduction ROM.

Other overhead sports

The evidence available for other overhead sports was express to two prospective cohorts from the same group of researchers for handball, and i prospective cohort each for softball, volleyball, lawn tennis and swimming.

The 2 studies15 39 that screened absolute shoulder ROM of the throwing arm in handball players plant opposite results. Clarsen et al 15 reported a minor positive association betwixt shoulder total rotation ROM and injury and no clan for internal rotation ROM. In contrast, Andersson et al 39 reported a small positive association between shoulder internal rotation ROM and injury and no clan for total rotation ROM. Caution is warranted when interpreting the results from Andersson et al 39 due to the poor inter-rater and intrarater reliability of the ROM measurements. These studies also have some methodological differences that may, in part, explain these contradictory results. Clarsen et al fifteen included only male handball players, while Andersson et al 39 included both male and female. Each report used different confounders to adapt their analysis. Although both studies used the aforementioned definition of overuse injury consequent with a non-contact injury mechanism, Clarsen et al 15 acknowledged the inclusion of injuries that were astute flare-ups of chronic problems, long-term problems initially caused an astute trauma or purely caused past an astute trauma. The inclusion of astute injuries may besides explain the higher injury rate (52%) reported by Clarsen et al fifteen compared with the report of Andersson et al 39 (22%).

While swimmers take different biomechanical demands compared with throwing sports, shoulder pain and injuries are common due to the high repetitions of overhead move and training volume.ii Based on the results of i report,13 swimmers with external rotation ROM in the depression and high tertiles are at higher risk of shoulder and elbow injuries compared with swimmers whose shoulder external rotation ROM is inside 93° and 100° (middle tertile). These results are contained of swimming preparation distance (tabular array two).13 This ideal external rotation ROM may be protective against shoulder injury, but confirmation of this finding in a 2nd independent accomplice of swimmers is needed before making strong recommendations for the use of shoulder ROM screening in this population.21

Absolute shoulder ROM or shoulder ROM deficits were not associated with shoulder or elbow injury in high school softball players,12 shoulder pain in professional person volleyball players14 or upper extremity injury in tennis players.40

Limitations

We admit several limitations. Few prospective studies were identified for sports such every bit handball, softball, tennis, volleyball and swimming. The small number of studies included in each ROM meta-analysis (3 out of 15, twenty%) is a significant limitation. With few studies, coverage of the overall upshot size is of concern, and i cannot be certain that one big study is non determining the overall event. Statistical power is limited when the number of studies is low. Lastly, the pocket-size number of studies prevented subgrouping within in each meta-analysis.

At that place was a high degree of heterogeneity among studies for age (youth to adults), position in baseball (pitchers only to combined accomplice of pitchers and field players), competition level (competitive to professional athletes) and injury definition (overuse questionnaires, league managed disable lists, combination of symptoms and sonographic findings, symptom duration, and missing time from sport performance, from 1 game/exercise, up to iii weeks). Combining studies with substantial heterogeneity can mask true differences between studies. Information technology can also lead to combining valid studies with biassed enquiry, producing a biassed overall judge.

In-season injuries often occur several weeks or months after screening (preseason), and it is possible that the association between screening findings and injuries weakens over time. This is an inherent limitation of all the studies included in this systematic review, every bit none of the studies reported the time elapsed betwixt screening and injury. Future studies should investigate whether more than frequent in-flavour screenings of factors theorised to relate to injury risk provide amend identification of overhead athletes at hazard of injury. Most of the included studies did not account for previous injury or exposure (ie, frequency of sport-related activities) in the analysis. This is an important limitation as these factors take been linked to injury and can be potential confounders. The aetiology of injury is multifactorial, and shoulder ROM represents only one risk factor for shoulder and elbow injuries. Thus, the results of this systematic review and meta-assay should be interpreted with caution.

Conclusion

Accented shoulder ROM or shoulder ROM differences practice not appear to be consistent risk factors for shoulder and elbow injuries beyond different overhead athletes. Age, competition level and position should be considered when screening the shoulder ROM of baseball thespian. Professional baseball pitchers whose external rotation ROM in the throwing arm was not at least 5° greater than their non-throwing arm were twice as likely to sustain in-flavor shoulder or elbow injuries. Similar findings were non observed in adolescent or high school baseball pitchers. Limited evidence suggested that swimmers with abnormally low or high external rotation are at higher risk of shoulder injuries. Limited evidence suggested that ROM screening may not be effective to identify handball, softball, volleyball and tennis players at run a risk of shoulder and elbow injuries.

What is already known

  • The repetitive demands of overhead sport lead to side-to-side changes in shoulder range of motility (ROM), such as increased external rotation and decreased external rotation. Nonetheless, injured overhead athletes have impairment of shoulder ROM compared with non-injured overhead athletes.

What are the new findings

  • Professional baseball pitchers whose external rotation ROM in the throwing arm is not at least 5° greater than the non-throwing arm were twice as likely to sustain in-flavor shoulder or elbow injuries

  • Limited testify: swimmers with external rotation of less than 93° or greater than 100° may be at higher run a risk of shoulder injuries than swimmers whose ROM is between those limits.

  • Limited show: ROM screening may not be constructive to identify handball, softball, volleyball and lawn tennis players at hazard of shoulder and elbow injuries.

Acknowledgments

We acknowledge Robert Edward Johnson, University of Southern California, for developing and conducting the systematic search of the databases.

Supplementary materials

  • Supplementary Data

    This web only file has been produced past the BMJ Publishing Group from an electronic file supplied by the author(s) and has non been edited for content.

    • Data supplement 1
    • Data supplement 2

Request Permissions

If you wish to reuse whatever or all of this commodity delight use the link beneath which volition take you lot to the Copyright Clearance Center's RightsLink service. You lot will be able to get a quick cost and instant permission to reuse the content in many different ways.

Copyright information:

© Author(s) (or their employer(southward)) 2020. Re-use permitted nether CC Past. Published by BMJ. https://creativecommons.org/licenses/by/4.0/ This is an open admission article distributed in accordance with the Artistic Commons Attribution iv.0 Unported (CC By 4.0) license, which permits others to re-create, redistribute, remix, transform and build upon this piece of work for any purpose, provided the original work is properly cited, a link to the licence is given, and indication of whether changes were made. See: https://creativecommons.org/licenses/by/four.0/.