Scapular Considerations in Racquet Sports

Injuries in the Racquet Sports

• Racquet sports, especially lawn tennis and badminton have been gaining popularity in Asian countries like India.
• With this increase in popularity, the injury rate in the sport has also increased.
• The injury rate in tennis varies from 0.04 injuries/1000 hours to 21.5 injuries/1000 hours
• Pluim BM, Staal JB (2006)
• Different overhead sports show different characteristics, but have similar movement patterns.
• In each, the dominant upper limb is subjected to repeated overhead movements.
• Torres RR, Gomes JL (2009), Wilk KE, Meister K (2002)

Racquet Sports – Biomechanics

• The mechanics of an overhead stroke or serve in racquet sports are similar to that of an overhead throw, wherein the shoulder has to be lax enough to allow the extra degrees of external rotation necessary for an adequate serve and at the same time has to be stable enough to prevent any subluxations.
• Craig A. (1995)
• This delicate balance between mobility and stability is referred to as ‘throwers paradox’ and if compromised, can lead to injury.
• Wilk KE, Meister K (2002)

• A racquet serve/stroke is a combination of true gleno-humeral rotation, trunk hyperextension and scapulo-thoracic motion.
• The cocking phase maintains the dominant arm in 90° abduction and external rotation which reaches a maximum of 172° to 180° during the late cocking phase.
• Fleisig GS, Barrentine SW (1996), Fleisig G, Nicholls R (2003), van der Hoeven H, Kibler WB. (2006)
• It ends with internal rotation and forward flexion of the dominant shoulder along with upper torso and pelvic rotation during the follow through phase.
• Jason A. (2007) 

The GIRD:

• Each phase places an asymmetric load between the two shoulders, with the dominant shoulder exposed to maximum stress. Jason A. (2007) 
• Studies have shown a significant difference in the gleno-humeral internal rotation range of motion between dominant and non-dominant shoulders of overhead sport players.
• Shimpi AP, Shah B (2015). Shah N, Shimpi AP (2016)
• This is defined as ‘Gleno-humeral internal rotation deficit’ (GIRD), which is the loss in degrees of the gleno-humeral internal rotation of the throwing shoulder compared with the non-throwing shoulder.
• Burkhart SS, Morgan CD, Kibler WB. (2003)
• An accepted level of GIRD is less than 20° deficit of gleno-humeral internal rotation or less than 10% deficit of the total rotation seen in throwing shoulder as compared to the non-throwing shoulder.
• Burkhart SS, Morgan CD, Kibler WB. (2003)
• The scapula provides a stable base to the movement of humeral head during an overhead motion. The stability of the scapula becomes important in these movement patterns. Jason A. (2007) 

SICK Scapula….

• An asymmetry develops in the scapular posture of overhead athletes like tennis players, where the dominant scapula is more protracted than the non-dominant side.
• Oyama S, Myers JB (2008). Shimpi AP, Shah B (2015)
• The acronym SICK scapula (scapular malposition, inferior medial border prominence, coracoid pain and malposition and dyskinesis) is used to describe this asymmetry of scapula.
• Burkhart SS, Morgan CD, Kibler WB  (2003)
• This asymmetry is accentuated in unilateral overhead athletes who use their dominant shoulder repetitively in a forceful manner.
• Oyama S, Myers JB (2008). Shimpi AP, Shah B (2015)
• Many authors suggest that this increased scapular protraction along with GIRD, increases the likelihood of shoulder injuries in these players.
• Wilk KE, Obma P (2009). Thomas SJ, Swanik KA (2010)
• Shoulder girdle injuries account for 17.27% in racquet players with 43.4% of elite tennis players presenting with scapular dyskinesia.
• Borsa PA, Laudner KG (2008). Kondric M, Matkovic BR (2011)
• Studies have also shown a positive association between a dyskinetic scapula with posterior shoulder tightness and GIRD in the dominant arm of overhead players.  Laudner KG, Moline MT (2010). McClure P, Greenberg E (2012)
• During the follow through phase, the scapula has to protract around the thoracic wall in order to help dissipate the energy.
• Kibler WB. (1991). Voight ML, Thomson BC. (2000)
• In the presence of considerable GIRD, the players have to bring about increased scapular protraction to compensate for the reduced internal rotation in order to maintain the velocity of the overhead stroke.
• Thomas SJ, Swanik KA (2010). Shimpi AP, Shah B (2015)
• With time, this continuous stress causes soft tissue adaptations and leads to weakness of the scapular stabilizers, mainly the lower fibres of rhomboids causing an upward rotation.
• Thomas SJ, Swanik KA (2010). Shimpi AP, Shah B (2015)
• Thus, the scapula cannot provide a stable base of support for the rotator cuff to function, which reduces its efficiency and increases stress on the static restraints of the dominant shoulder. Thomas SJ, Swanik KA (2010)

• So, rather than compressing the humeral head into the glenoid fossa, the rotator cuff pulls the scapula upward and laterally resulting in greater scapular protraction and external rotation.
• Kibler WB. 1998. Shimpi AP, Shah B (2015). Shah N, Shimpi AP (2016)

Why Scapular Perspective?

• During the follow through phase of an overhead motion, the shoulder joint is subjected to distractive forces of up to 750N which is mainly resisted by the postero-inferior capsule.
• van der Hoeven H, Kibler WB. (2006)
• With repetitive loading, the posterior capsule is said to undergo micro trauma causing hypertrophy and increased fibroblastic activity during the healing process, leading to contracture and thickening of the capsule. Thomas SJ, Swanik KA (2010)
• This reduces the capsular pliability causing restriction of internal rotation, extension and horizontal adduction.
• van der Hoeven H, Kibler WB. (2006). Thomas SJ, Swanik KA (2010). Shimpi AP, Shah B (2015)

• A posterior capsule stretching program incorporated in the rehabilitation and training of overhead players is reported to reduce the incidence of GIRD.

• It also reduces the incidence of shoulder injuries like Superior Labrum Anterior Posterior (SLAP) lesions in these players.
• Burkhart SS, Morgan CD, Kibler WB (2003)
• Arthroscopic studies have also shown increased thickness and hypertrophy of capsule in the postero-inferior recess of dominant arm of throwers and its positive association with GIRD, external rotation and scapular upward rotation. Thomas SJ, Swanik CB (2011)
• Studies have shown that for a 4° decrease in internal rotation, there is 1cm decrease in horizontal adduction, which is an indicator of posterior capsule tightness.
• Torres RR, Gomes JL (2009)
• Studies also showed a significant increase in the external rotation of the dominant shoulder compared to non-dominant side in racquet players and when compared to dominant side of non-racquet players.
• Shimpi AP, Shah B (2015)
• One of the causes can be attributed to the contracted or shortened posterior band of the inferior gleno humeral ligament (IGHL) which primarily provides restraint to further movement in position of maximum abduction and external rotation during late cocking phase. Burkhart SS, Morgan CD, Kibler WB. (2003)
• It prevents posterior migration of humeral head, thus centering it in the glenoid fossa allowing a normal arc of movement.
• van der Hoeven H, Kibler WB  (2006)
• Arthroscopic findings in overhead players show contractures and thickening in the zone of the posterior band of IGHL.
• van der Hoeven H, Kibler WB  (2006)

• The tethered posterior band draws the humeral head postero-superiorly to a new point of rotation on the glenoid, thus causing an abnormal increase in the external rotation due to easier clearance of the greater tuberosity.
• van der Hoeven H, Kibler WB  (2006)
• The postero-superior migration of humeral head also reduces the cam effect of the humeral head and antero-inferior humeral calcar on the antero-inferior capsule leading to redundancy in the antero-inferior capsule, allowing hyper external rotation of the dominant arm. Burkhart SS, Morgan CD, Kibler WB. (2003). Burkhart SS (2007)

• Another explanation for the increased external rotation can be possibly attributed to increased humeral retroversion which is a common finding in players playing overhead sports.
• Kibler WB, Sciascia A (2012)
•  This change in the humeral head causes a shift in the arc of rotation of the dominant shoulder favoring external rotation.
• Tokish JM, Curtin MS (2008)
• However, the studies suggest that the total arc of rotation remains the same, as any increase in the external rotation will require a corresponding decrease in the internal rotation, which will be permanent. Lintner D, Mayol M (2007)

• There exists presence of abnormal scapular resting position in asymptomatic racquet players on the dominant side in the form of scapular external rotation and elevation on the dominant side as compared to their non-dominant side.
• There also exists presence of gleno-humeral movement dysfunction in the form of reduced internal rotation, extension and adduction and gain in external rotation on the dominant side.
• A comparison between symptomatic and asymptomatic players could help determine the pathological threshold for injury predisposition.
• ROM and scapular resting position can be used as a screening tool for injury prevention in overhead racquet players.
• Shimpi AP, Shah B (2015). Shah N, Shimpi AP (2016)

Advanced Training

• Most important is to prepare the athlete for a long term, not just for the coming season.
• Nyland J (2010)
• Functional exercises simulating the athletes role and Sports Specific Scapular training is extremely important.
• This helps in gaining an excellent neuromuscular control and functioning.
• More useful in establishing athletes self efficacy and confidence as movements closely resemble the athletes sports specific movements.
• Nyland J (2013)
• Functional training can be achieved by training the athlete in a sports simulation by:
• A. Uni-planar training the protractors.

• B. Uni-planar training of the retractors.

• C. Bi-planar motion training

• D. Multi-planar motion training.

• E. Simulation of the game with resistive training
• Nyland J (2011)

• Further enhancement can be obtained by using unstable surface like the BOSU for bodily challenges and further enhancement.
• Wankhede N, Shimpi A (Hypothesis)
• This can be challenged using:
• A. Strength training on BOSU

• B. Limb and trunk challenges

• C. Focused stability challenge

• D. Hit and serve challenges.

Summary

• Injured overhead athletes may display more asymmetry than healthy overhead athletes, and there may be a pathologic threshold for scapular posture asymmetry at which an asymmetry becomes problematic. Shimpi AP, Shah B (2015)
• Need of specific stretching and strengthening as a part of the pre-season training of racquet athletes to address muscular imbalances to provide optimum scapular and gleno-humeral stability to the shoulder to endure the demands of the game. Nyland J (2013)

• Need for advanced training to prepare the athlete in prevention of injuries and correct the problems before they become real problems for the athletes. Wankhede N, Shimpi A (Hypothesis)

References:

Shimpi AP, Bhakti S, Roshni K, Rairikar SA, Shyam A, Sancheti PK. Scapular Resting Position and Gleno-Humeral Movement Dysfunction in Asymptomatic Racquet Players: A Case-Control Study. Asian J Sports Med. 2015 Dec;6(4):e24053. doi: 10.5812/asjsm.24053. Epub 2015 Dec 1. PubMed PMID: 26715968; PubMed Central PMCID: PMC4691306.

https://www.ncbi.nlm.nih.gov/pubmed/26715968

Shah NA, Shimpi AP, Rairikar SA, Ashok S, Sancheti PK. Presence of scapular dysfunction in 

dominant shoulder of professional guitar players. Int J Occup Saf Ergon. 2016 Sep;22(3):422-5. 

doi:  10.1080/10803548.2016.1154720. Epub 2016 Mar 29. PubMed PMID: 27023289.

https://www.ncbi.nlm.nih.gov/pubmed/27023289

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