Consider shoulder changes, forces to diagnose, treat injuries in throwing athletes
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WAILEA, Hawaii — Physicians who treat throwing athletes should be familiar with the role that adaptive changes, kinetic chain, internal impingement, and throwing volume and force play in shoulder injuries, according to a presenter.
At Orthopedics Today Hawaii 2021, Christopher S. Ahmad, MD, an Orthopedics Today Editorial Board Member, said all those factors, which are interrelated, impact the throwing athlete’s shoulder and risk of shoulder injury.
“There [are] arm motions that are extreme, external rotation angulation. There [are] features of throwing — immaturity, fatigue — that lead to weakness in the kinetic chain. Then, you start to get the trauma of internal impingement; but if it goes too far, you get unstable. You rip capsules and you get subluxations, and the impingement goes too far. Then you get symptoms related to the rotator cuff and to the [superior labrum anterior-posterior] SLAP lesion,” he said, noting this is a complex area in regard to diagnosis and treatment.
Concerning shoulder adaptation, Ahmad said the younger the athlete is, the more bone adaptation or remodeling occurs following an injury and the greater the response of soft tissues is to anterior capsule laxity. The same goes for shoulder retroversion, which is about 70° at birth and changes with age.
“Baseball players at the mature level – they have more retroversion, up to 17° more on their throwing shoulder than their not-throwing shoulder – what likely happens is that, during their throwing and development, they don’t correct or go all the way to that 20° to 30° mark. They get more retroversion,” Ahmad said.
With age, baseball players develop increased external rotation (ER) on their throwing side, which causes bone changes. Athletes offset the added ER with decreased internal rotation. “There’s something happening to the soft tissue that allows them to externally rotate,” he said, noting that in hard throwers such alteration can affect the anterior capsule and may result in a capsular tear.
The resultant effect on the posterior capsule, however, is extreme thickening, which Ahmad has seen be up to five times the capsule’s normal thickness.
“[The] kinetic chain is so important,” including the elbow, legs, arm position and stance, Ahmad said. When it is ignored, it can sometimes be career-ending, he noted.
Ahmad also discussed how important it is for physicians to be aware of shoulder internal impingement that does not involve the acromion, but rather affects the undersurface of the rotator cuff when it hits — and damages — the posterior superior glenoid in the throwing position.
Physicians and trainers must also address core muscles and strength in the throwing athlete. These factors allow for the athlete’s safe play, according to Ahmad.
“Their legs are so strong. Their upper body’s so strong. The forgotten part is this oblique,” he said.
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Ahmad CS. Throwing shoulder injuries made simple. Presented at: Orthopedics Today Hawaii 2021; May 30-June 3, 2021; Wailea, Hawaii.
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