While a throw maybe artificially divided into various phases like wind up, cocking, acceleration, degeneration and ball release, and follow through, the forces acting through the phases a are real and so are the injuries that can happen.
The throwing motion puts a lot of stress on the shoulder and the injuries that these athletes ( javelin throwers, baseball pitchers, cricket ball throwers) sustain may be different to those who are not involved in overhead sports. The forces generated in the shoulder can be enormous and cause over use injuries to the cuff and labral tissues. In the kids it may lead to inflammation and separation of the growth plate.
Anterior impingement injuries occur due to the cuff and biceps tendon getting pinched under the acromion and coraco acromial arch. Posterior tension injuries occur during the deceleration phase of throwing where the posterior muscles are countering the excessive anterior force. The posterior cuff muscles may fail under tension. The tears usually occur on the underside of the cuff. Avulsion injuries to the labrum when it is pulled eccentrically by the biceps Contraction during the deceleration phase of ball release. Repeated throwing also puts a lot of stress on the anterior labrum, capsule and glenoid, leading to anterior instability in the end.
Instability, ususally anterior, is usually diagnosed clinically, with MRI confirming the findings. Strengthening around the shoulder is initiated, failure of which may warrant a shoulder Arthroscopy and repair of the detached labrum.
Throwers can sustain injuries to the Biceps tendon too, Especially due to its eccentric contraction during the follow through phase. This may be treated conservatively with appropriate rest and strenghtening. Failing which an Arthroscopy may be indicated for a simple debridement or a tenotomy with tenodesis
Rotator cuff problems can be due to impingement, instability or due to tensile failure of the cuff, in the throwers. Instability and tensile failure seem to cause under surface partial tears, which may be treated with physio and rehabilitation initially, by stretching the posterior capsule and strengthening the Rotator Cuff. Failure to improve will lead to arthroscopic debridement, and perhaps repair. If underlying Instability is a cause that has to be addressed, just like a subacromial decompression that may be necessary to address a sub acromial impingement.
Other issues that one might encounter while treating throwing athletes with shoulder pain are wear and tear of cartilage (osteochondritis dissecans), nerve (supra-scapular nerve) and artery (quadrilateral space) entrapments, Acromia-clavicular joint degeneration, Bony growth (Thrower's exostosis) and growth plate injuries (little league shoulder) in kids.
.
