Thrower’s Shoulder; Causes, Symptoms , Diagnosis Treatment

Thrower’s shoulder has long been a topic of debate among shoulder specialists. The tremendous forces produced during the throwing motion coupled with the compilation of the pathology encountered in the thrower’s shoulder have generated a complex treatment algorithm. Simplifying management options has been challenging and recommendations continue to evolve. Treatment of injuries to the thrower’s shoulder most commonly involves addressing partial articular-sided rotator cuff tears. These can be isolated or more commonly associated with tearing of the posterior superior labrum. The understanding of the dramatic difference between the surgical treatment of shoulder injuries in overhead athletes and nonoverhead athletes is paramount to positive outcomes after surgery.

The throwing athlete’s shoulder is a unique, complex entity with challenges in diagnosis and management. The shoulders in these athletes possess unique biomechanics and pathologic conditions. Unfortunately, return to play outcomes are often poor when specifically evaluating overhead athletes, especially with regard to a SLAP repair. It is imperative for the surgeon to be cautious when indicating these athletes for surgery because although they may demonstrate improvements in pain and general function, subtle changes in accuracy or velocity as a result of surgery can significantly affect the success of an overhead throwing athlete at the competitive level.

Anatomy

Superior glenohumeral ligament

• runs from the superior aspect of the glenoid and coracoid process to the fovea capitis just superior to the lesser tuberosity of the humerus
• initially anterior then anteroinferior to the long head of the biceps tendon; stabilizes the biceps brachii tendon ³

Middle glenohumeral ligament

• runs from the anterosuperior glenoid, arising just inferior to the superior GHL, to the anterior aspect of the anatomic neck of the humerus

Inferior glenohumeral ligament

• sometimes referred to as the inferior glenohumeral ligament complex
• runs from the inferior two-thirds of the glenoid labrum and/or neck to the lateral humerus
• composed of three parts
  • anterior band
  • posterior band
  • axillary pouch: laxity between anterior and posterior bands
• most important of the three GHLs as it prevents dislocation at the extreme range of motion and is the main stabilizer of the abducted shoulder 

Spiral glenohumeral ligament

• also referred to as fasciculus obliquus 
• runs from the infraglenoid tubercle and triceps tendon to the lesser tubercle of the humerus where it shares an insertion with the subscapularis tendon
• not well-known, but consistently demonstrated on both anatomic dissection and MR arthrography

Variant anatomy

• superior GHL is almost always present (97%) but has a variable origin, arises with biceps brachii tendon, arises with middle GHL
• middle GHL is variable in size and appearance ¹ and absent in 30% forms part of the Buford complex.

Pathophysiology

Causes of Thrower’s Shoulder

Buford complex is a congenital glenoid labrum variant where the anterosuperior labrum is absent in the 1-3 o’clock position and the middle glenohumeral ligament is thickened (cord-like) and originates directly from the superior labrum at the base of the biceps tendon and crosses the subscapularis tendon to insert on the humerus. It is present in approximately 1.5% of individuals.

Of the five phases that make up the pitching motion, the late cocking and follow-through phases place the greatest forces on the shoulder.

• Late-cocking phase – in order to generate maximum pitch speed, the thrower must bring the arm and hand up and behind the body during the late cocking phase. This arm position of extreme external rotation helps the thrower put speed on the ball, however, it also forces the head of the humerus forward which places significant stress on the ligaments in the front of the shoulder. Over time, the ligaments loosen, resulting in greater external rotation and greater pitching speed, but less shoulder stability.
• Follow-through phase-  During acceleration, the arm rapidly rotates internally. Once the ball is released, follow-through begins and the ligaments and rotator cuff tendons at the back of the shoulder must handle significant stresses to decelerate the arm and control the humeral head.
• Rotator cuff (RC) tendonitis/tendinosis – acute or chronic tendinopathic conditions that result from a vulnerable environment for the RC secondary to repetitive eccentric forces and predisposing anatomical/mechanical risk factors. Acute injuries and chronic overuse can result in focally weakened cuff regions. These vulnerable areas evolve into PTTs or FTTs, depending on the type of eccentric forces experienced by the RC.[rx]
• Shoulder impingement – a clinical term often used nonspecifically to describe patients experiencing pain/symptoms with overhead activity.
• Internal impingement[rx] –  common in overhead-throwing athletes such as baseball pitchers and javelin throwers. Impingement occurs at the posterior/lateral articular side of the cuff as it abuts the posterior/superior glenoid rim and labrum when the shoulder is in maximum abduction and external rotation (i.e., the “late cocking” phase of throwing) The term, “thrower’s shoulder” refers to a common set of anatomic adaptive changes that occur over time in this subset of athletes. These adaptive changes include but are not limited to increased humeral retroversion and posterior capsular tightness. Glenohumeral internal rotation deficit (GIRD) is a condition resulting from these anatomic adaptations, and GIRD is known to predispose the thrower’s shoulder to internal impingement.
• External impingement –  a term used synonymously with SIS. External impingement (EI) encompasses etiologies of external compressive sources (i.e. the acromion) leading to subacromial bursitis and bursal-sided injuries to the RC.[rx][rx][rx]
• Mechanism of injury – The two described mechanisms for acute tears of the triceps are direct contact trauma, such as a fall or hitting fixed resistance with the posterior elbow[rx,rx,rx,rx]. Weightlifting[rx,rx,rx,rx,rx–rx] was the most common sport associated with acute tears and was often associated with a history of steroid use[rx,rx,rx]. American football[rx,rx] and general sports injuries[rx], as well as direct lacerations[rx] have all also been reported as a mechanism
• Trauma – Injuries to the triceps, such as a muscle tear from placing too much force on the muscle, can lead to pain.
• Repetitive stress – Repeating the same shoulder motions, again and again, can stress your triceps muscles and tendons. Baseball, tennis, rowing, and weightlifting are examples of sports activities that can put you at risk for overuse tears. Many jobs and routine chores can cause overuse of tears, as well.
• Lack of blood supply – As we get older, the blood supply in our triceps brachiilessens. Without a good blood supply, the body’s natural ability to repair tendon damage is impaired. This can ultimately lead to a tendon tear.
• Bone spurs – As we age, bone spurs (bone overgrowth) often develop on the underside of the acromion bone. When we lift our arms, the spurs rub on the triceps brachii muscle. This condition is called shoulder impingement, and over time will weaken the tendon and make it more likely to tear.
• Sudden forceful  fall down
• Road traffic accident
• Falls – Falling onto an outstretched hand is one of the most common causes of injury.
• Sports injuries – Many Injury occurs during contact sports or sports in which you might fall onto an outstretched hand — such as in-line skating or snowboarding.
• Motor vehicle crashes – Motor vehicle crashes can cause necks of femur fracture to break, sometimes into many pieces, and often require surgical repair.
• Have osteoporosis –  a disease that weakens your bones
• Eave low muscle mass or poor muscle strength – or lack agility and have poor balance (these conditions make you more likely to fall)
• Walk or do other activities in the snow or on the ice – or do activities that require a lot of forwarding momenta, such as in-line skating and skiing
• Wave an inadequate intake of calcium or vitamin D
• Football or soccer, especially on artificial turf
• Rugby
• Horseback riding
• Hockey
• Skiing
• Snowboarding
• In-line skating
• Jumping on a trampoline

Symptoms Of Thrower’s Shoulder

Depending on the cause of your shoulder pain you may experience

• Pain deep in the shoulder joint, in the back or the front of the shoulder and the upper part of the arm. Sometimes the pain in the shoulder can be described as a ‘catching pain’. The location and type of pain is likely to relate to the structure causing the pain
• Reduced movement, and pain when moving your shoulder.
• The weakness of the shoulder/upper arm. Depending on the condition, there may be a sensation of the joint slipping out and back into the joint socket, or the shoulder can become completely dislodged (dislocated)
• Sensations of pins and needles (tingling) and burning pain. This is more likely to be associated with nerves from the neck than the shoulder joint itself.
• Lack of movement after a shoulder dislocation. This is usually due to pain. Complete rotator cuff tears and injury to the axillary nerve both cause weakness in moving the arm away from the body. These problems require close clinical examination.

Symptoms Of 

• Pain in the muscle after impact.
• Pain and difficulty when lifting the arm to the side.
• Tender to touch the muscle.
• Bruising appears.
• There may be some swelling

Diagnosis of Thrower’s Shoulder

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Supraspinatus

• Jobe’s test – the positive test is pain/weakness with resisted downward pressure while the patient’s shoulder is at 90 degrees of forwarding flexion and abduction in the scapular plane with the thumb pointing toward the floor.
• Drop arm test –  the patient’s shoulder is brought into a position of 90 degrees of shoulder abduction in the scapular plane. The examiner initially supports the limb and then instructs the patient to slowly adduct the arm to the side of the body. A positive test includes the patient’s inability to maintain the abducted position of the shoulder and/or an inability to adduct the arm to the side of the trunk in a controlled manner.

Infraspinatus (IS)

• Strength testing is performed while the shoulder is positioned against the side of the trunk, the elbow is flexed to 90 degrees, and the patient is asked to externally rotate (ER) the arm while the examiner resists this movement.
• External rotation lag sign: the examiner positions the patient’s shoulder in the same position, and while holding the wrist, the arm is brought into maximum ER. The test is positive if the patient’s shoulder drifts into internal rotation (IR) once the examiner removes the supportive ER force at the wrist.

Teres Minor (TM)

• Strength testing – is performed while the shoulder positioned at 90 degrees of abduction and the elbow is also flexed to 90 degrees. Teres minor (TM) is best isolated for strength testing in this position while ER is resisted by the examiner.
• Hornblower’s sign –the examiner positions the shoulder in the same position and maximally ERs the shoulder under support. A positive test occurs when the patient is unable to hold this position and the arm drifts into IR once the examiner removes the supportive ER force.
• IR lag sign –  the examiner passively brings the patient’s shoulder behind the trunk (about 20 degrees of extension) with the elbow flexed to 90 degrees. The examiner passively IRs the shoulder by lifting the dorsum of the handoff of the patient’s back while supporting the elbow and wrist. A positive test occurs when the patient is unable to maintain this position once the examiner releases support at the wrist (i.e., the arm is not maintained in IR, and the dorsum of the hand drifts toward the back)
• Passive ER ROM – a partial or complete tear of the subscapularis (SubSc) can manifest as an increase in passive ER compared to the contralateral shoulder.
• Liftoff test – more sensitive/specific for lower SubSc pathology. In the same position as the IR lag sign position, the examiner places the patient’s dorsum of the hand against the lower back and then resists the patient’s ability to lift the dorsum of the hand away from the lower back.
• Belly press –  more sensitive/specific for upper subscapularis pathology. The examiner has the patient’s arm at 90 degrees of elbow flexion, and IR testing is performed by the patient pressing the palm of his/her hand against the belly, bringing the elbow in front of the plane of the trunk. The elbow is initially supported by the examiner, and a positive test occurs if the elbow is not maintained in this position upon the examiner removing the supportive force.

External impingement/SIS

Pertinent findings

The most common radiographic changes associated with EI/SIS and RCS include:

• RCA – Proximal humeral migration and decreases in the acromiohumeral interval to < 7 mm
• Degenerative findings:
  • osteophytes on the acromion, proximal humerus and/or glenoid are often seen in cases of advanced disease
  • calcification of the CAL and/or coracohumeral ligament (CHL)
  • greater tuberosity cystic degeneration
  • AC joint arthritis
• Hooked” acromion- best appreciated on the supraspinatus outlet view
• Os acromiale- best seen on an axillary lateral radiograph

Imaging Tests

Your doctor may order tests to confirm your diagnosis and identify any associated problems.

• X-rays – This imaging test creates clear pictures of dense structures, like bone. X-rays will show any problems within the bones of your shoulder, such as arthritis or fractures.
• Magnetic resonance imaging (MRI) – This imaging study shows better images of soft tissues. It may help your doctor identify injuries to the labrum, ligaments, and tendons surrounding your shoulder joint.
• Computed tomography (CT) scan – This test combines x-rays with computer technology to produce a very detailed view of the bones in the shoulder area.-
• Ultrasound – Real-time images of muscles, tendons, ligaments, joints, and soft tissues can be produced using ultrasound. This test is typically used to diagnose rotator cuff tears in individuals who are not able to have MRI scans.

Ultrasound

• Ultrasound (US) is an often-underutilized imaging modality to detect RC tendon and muscle belly integrity. In 2011, a meta-analysis of over 6,000 shoulders revealed a sensitivity of 0.96 and specificity of 0.93 in assessing shoulders for partial- or full-thickness cuff tears. Another study highlighted the potential inability to differentiate between partial- and full-thickness cuff tears (PTT versus FTT) measuring about 1 cm in size.

Magnetic Resonance Imaging

• Magnetic Resonance Imaging (MRI) is useful in evaluating the overall degree of RC pathology. MRI can be helpful in providing more accurate cuff tear details, including partial- versus full-thickness tears, the extent and size of the tear(s), location, and the degree of retraction. In cases of chronic RC pathology, the cuff can be assessed for fatty degenerative changes on the T1-weighted sagittal sequence series.[rx]

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Treatment of Thrower’s Shoulder

Nonsurgical Treatment

In many cases, the initial treatment for a throwing injury in the shoulder is nonsurgical. Treatment options may include:

• Activity modification – Your doctor may first recommend simply changing your daily routine and avoiding activities that cause symptoms.
• Ice –  Applying icepacks to the shoulder can reduce any swelling.
• Anti-inflammatory medication – Drugs like ibuprofen and naproxen can relieve pain and inflammation. They can also be provided in the prescription-strength form.
• Physical therapy – In order to improve the range of motion in your shoulder and strengthen the muscles that support the joint, your doctor may recommend specific exercises. Physical therapy can focus on muscles and ligament tightness in the back of the shoulder and help to strengthen the structures in the front of the shoulder. This can relieve some stress on any injured structures, such as the labrum or rotator cuff tendon.
• Change of position – Throwing mechanics can be evaluated in order to correct body positioning that puts excessive stress on injured shoulder structures. Although a change of position or even a change in sport can eliminate repetitive stresses on the shoulder and provide lasting relief, this is often undesirable, especially in high-level athletes.
• Cortisone injection— If rest, medications, and physical therapy do not relieve your pain, an injection of a local anesthetic and a cortisone preparation may be helpful. Cortisone is a very effective anti-inflammatory medicine. Injecting it into the bursa beneath the acromion can provide long-term pain relief for tears or other structural damage.

Throwers

• Special attention to preoperative internal rotation deficit and scapular dyskinesis
• Consider internal impingement as a cause of pain
• Special attention to the posterior aspect of the supraspinatus and anterior infraspinatus
• Special attention to the posterior superior labrum
• Consider debridement of partial rotator cuff tears and posterior superior labral tears
• Postoperative accelerated thrower’s rehabilitation.

Nonthrowers

• Special attention to preoperative strength and night pain
• Consider external impingement as a cause of pain
• Special attention to the anterior aspect of the supraspinatus
• Special attention to the acromial morphology or acromioclavicular joint arthritis
• Consider completion and repair of the partial rotator cuff tear with acromioplasty and distal clavicle excision
• Postoperative immobilization and physical therapy

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Complications

References