Acute Batter's Shoulder With Concomitant Superior Labrum from Anterior to Posterior Injury in a Collegiate Baseball Player

Abstract

An 18-year-old collegiate baseball player sustained an acute batter's shoulder injury causing a posterior shoulder dislocation with type IX 360° superior labrum from anterior to posterior tear. To the authors' knowledge, this description of batter's shoulder is not within the literature. The patient ultimately underwent arthroscopic labral repair and has fully returned to sport. In understanding the complexity of the shoulder during the batter's swing, this case demonstrates an expansion to the previously described pathophysiology of batter's shoulder.

Batter's shoulder, first described in 2000 by Philips et al, is a unique form of unidirectional posterior shoulder instability defined as isolated posterior capsulolabral pathology from forces acting on a baseball batter's lead shoulder.^1,2 Marigi et al³ reported batter's shoulder to comprise approximately 2.1% of all shoulder pathologies caused by batting and 0.4% of all-cause shoulder pathology in a cohort of 3,414 professional baseball players. During the follow-through phase of batting, the lead shoulder experiences a posteriorly directed force of the humerus on the posterior capsulolabral structures because of the extreme position of the shoulder in a forward flexed, adducted, and internally rotated position.^2,4-6 In general, posterior shoulder instability is considerably less common relative to anterior shoulder instability in athletes, accounting for only 2% to 12% of patients with shoulder instability.^7-9

Batter's shoulder may occur as an acute or chronic process. Classically, a missed outside pitch is the mechanism of injury because of a lack of counterforce created by bat-on-ball contact, increasing the adduction angle of the shoulder and exacerbating the posterior force and shear forces across the shoulder, resulting in an isolated posterior labral tear.^2,10 We present a case of acute batter's shoulder resulting in notable injury to the glenohumeral joint superseding the isolated posterior labral pathology typically seen. Informed consent was obtained from the patient stating that the case would be submitted for publication.

Case Report

The patient is a healthy 18-year-old male, right-hand and right-batting–dominant, division 1 collegiate baseball player who injured his left shoulder during a game. He is a nonpitching positional player and had no previous left shoulder pain or trauma before this incident. During an at-bat, while swinging at a high-center fastball, he made minimal contact with the ball and experienced a pop and immediate pain in his leading shoulder during the follow-through phase of his swing (Figure 1). He was unable to continue playing and exited the game. Ultimately, after a week of rehabilitation with university athletic training staff, he was unable to return to play because of pain.

Figure 1.

In-game photographs showing the patient during injury at-bat. A, Mid-swing phase of the baseball swing. B, Follow-through phase of baseball swing; moment of injury. Note that the lead shoulder is in a forward flexed, adducted, and internally rotated position.

At orthopaedic evaluation 10 days after injury, he reported no additional episodes of instability, only subjective pain, and decreased strength of the left shoulder. Physical examination demonstrated tenderness to the anterior shoulder and biceps groove. Active and passive range of motion (ROM) showed abduction and flexion to 170°, external rotation to 70°, internal rotation to the thoracic spine associated with pain, and 5/5 strength in all planes of motion. Provocative testing was negative for AP instability or apprehension, including the load and shift test, jerk test, and Kim test. Neer, Yergason, and O'Brien active compression and cross-body adduction tests were positive. Radiographs demonstrated a reduced glenohumeral joint without acute fracture (Figure 2). Owing to clinical concerns for labral pathology from select positive superior labrum from anterior to posterior (SLAP) lesion provocative testing, physical therapy was prescribed and magnetic resonance imaging (MRI) without contrast of the left shoulder was ordered.

Figure 2.

A, Left shoulder radiographs obtained at the first orthopaedic outpatient clinic appointment showing a reduced glenohumeral joint without acute fracture and preserved joint spaces. Anterior-posterior radiograph. B, Scapular Y view radiograph. C, Axillary view radiograph.

MRI demonstrated a reverse Hill-Sachs lesion measuring 1 × 1 × 2 cm and a reverse soft-tissue Bankart lesion, with a concomitant 360° circumferential labral tear, reflecting a type IX SLAP lesion. In addition, a tear of the posterior glenohumeral joint capsule and a low-grade, articular-sided, partial-thickness tear of the supraspinatus tendon were demonstrated (Figure 3). Physical therapy focused on rehabilitation of periscapular musculature, rotator cuff strength, passive ROM with progression to active ROM, and light isometric strengthening. After failing a 4-week course of therapy, the patient was indicated for arthroscopic labral repair because of persistent pain and inability to return to sport.

Figure 3.

Left shoulder fat-suppressed proton density 3T MRI radiographs demonstrating a reverse Hill-Sachs lesion, reverse Bankart lesion, and type IX SLAP lesion. A, Axial images showing the reverse Hill-Sachs lesion (white arrows) with associated bone edema and reverse Bankart lesion, as well as anterior and posterior labral tears (red arrows). B, Axial images showing the reverse Hill-Sachs lesion (white arrows) with associated bone edema and reverse Bankart lesion, as well as anterior posterior labral tears (red arrows). C, Coronal and sagittal fat-suppressed proton density MRI radiographs further characterize the injury, including a small articular surface, partial-thickness supraspinatus tendon tear (blue arrow). D, Coronal and sagittal fat-suppressed proton density MRI radiographs further characterize the injury, including a small articular surface, partial-thickness supraspinatus tendon tear (blue arrow). SLAP = superior labrum from anterior to posterior

Intraoperatively, the patient was positioned in lateral decubitus with hanging traction. Posterior and anterior rotator interval portals were established in a standard fashion. The type IX SLAP tear was confirmed; grade 0 chondromalacia was noted of both the humerus and the glenoid; the biceps tendon was seen intact; and a low-grade, articular-sided partial tear of the supraspinatus was débrided (Figure 4). At the 12 to 1 o'clock position, an Arthrex PEEK PushLock knotless anchor was used to secure the labrum and capsule onto the glenoid rim. This process was repeated moving anteroinferiorly for a total of four anchors in the anterior glenoid labrum. The viewing and working portals were then switched. In a similar fashion, starting at the 11 o'clock position and moving posteroinferiorly, a total of three anchors were placed in the posterior glenoid labrum, completing the labral repair (Figure 5).

Figure 4.

Intraoperative arthroscopic images before repair demonstrating a type IX SLAP tear and partial articular-sided rotator cuff tear. A, Anterior labrum tear viewed from the posterior portal. B, Posterior labrum tear viewed from the anterior portal. C, Partial-thickness, articular-sided rotator cuff tear. SLAP = superior labrum from anterior to posterior

Figure 5.

Intraoperative arthroscopic images post-repair. A, Anterior labrum after repair viewed from the posterior portal. B, Anterior labrum after repair viewed from the posterior portal. C, Posterior labrum after repair viewed from the anterior portal.

Postoperative rehabilitation consisted of a progressive five-phase protocol with university athletic training and physical therapy. Phase I (weeks 0 to 3) focused on shoulder protection and immobilization. Phase II (weeks 4 to 8) focused on progression of active-assist and active shoulder ROM, with restrictions on internal rotation to protect the repair, and muscle strengthening and neuromuscular control up to 45° abduction at low velocity. Phase III (weeks 9 to 12) focused on progression to full active ROM, including internal rotation, and muscle strengthening and neuromuscular control up to 90° abduction at low-to-mid velocity. Light resistance/high repetition training was also initiated. Phase IV (weeks 13 to 18) focused on continued strength and stability at mid-to-high velocity, with incorporation of provocative closed-chain exercise programs at low velocity to develop control on posterior forces. Phase V (weeks 18+) focused on return to sport, initiating high-velocity movements with continued strength and stability training. A formal throwing and batting progression protocol was initiated.

Ultimately, the patient was cleared to return to sport without restrictions at 20 weeks postoperatively. This was governed on being pain-free with full shoulder ROM, equal strength to the contralateral side, and ability to complete weight room activities and throwing and hitting progressions. At the time of writing, the patient was 17 months from surgery and doing well with no analgesic requirements, pain with activity, or mechanical symptoms. He has returned to full throwing, batting, and fielding, including game/season play, and reported preinjury throwing velocity and bat speed. His Disabilities of the Arm, Shoulder, and Hand questionnaire score 9 months postoperatively was 0.8, compared with 25.8 preoperatively. Physical examination showed active and passive shoulder abduction and flexion to 170°, external rotation to 70°, internal rotation to the thoracic spine without pain, and 5/5 strength in all planes of motion. Provocative testing was negative for AP instability or apprehension, including the load and shift test, jerk test, and Kim test. Neer, Yergason, O'Brien active compression and cross-body adduction testing were negative.

Discussion

We present an atypical severe presentation of acute batter's shoulder in a patient without antecedent shoulder pain or instability. Most often, batter's shoulder results from chronic microtrauma on the posterior capsulolabral complex from repeated swings leading to progressive fraying or tearing from increased translation of the humeral head on the glenoid.^2,10 Patients often describe progressive shoulder pain and increasing difficulty during the follow-through phase of batting.^2,4-6 Clinically, patients present with shoulder pain in positions of forward flexion, adduction, and internal rotation and may have varying degrees of posterior instability. Furthermore, evaluation may show a wide range of positive SLAP provocative maneuvers, but the load and shift test, jerk test, and Kim test are most predictive of posterior labral pathology.^11,12 Specifically, a combined positive jerk test and Kim test is roughly 97% sensitive for posteroinferior labral pathology.^11,12 This patient's clinical presentation of subjective shoulder pain and physical examination producing pain with internal rotation and adduction and select positive SLAP provocative testing, without instability or apprehension, is consistent with the previously described presentation of batter's shoulder being pain and not instability symptoms.⁴

Classically, batter's shoulder demonstrates an isolated posterior labral tear, as opposed to the type IX SLAP lesion seen in this case. Currently, the SLAP lesion classification includes 10 types, with the original Snyder classification incorporating types I-IV describing simple labral fraying to bucket handle tear with a detached biceps anchor. This classification was later expanded by Morgan, Maffet, Resnick, and Beltran to include types V-X and further subclassified type II lesions, with type IX being circumferential global labrum abnormality.¹ In addition, Kim et al¹³ described an arthroscopic and MRI arthrogram classification of posterior labral pathology, useful to demonstrate the chronic progression of batter's shoulder and severity of posterior capsulolabral derangement. This patient's pathology surpasses an isolated type IV posterior labral flap tear within the classification by Kim et al.

The patient experienced the classically described mechanism of injury, but sustained an unusual labral tear compared with the pathology typically seen, demonstrating an expansion to the pathophysiology of batter's shoulder. The degree of labral damage seen in this case was likely because of immense posterior traction force to the anterior capsulolabral structures and posterior shear force to the posterior capsulolabral structures sustained from a posterior dislocation because of an abnormally increased adduction angle of the shoulder during the follow-through phase of swing. Possibly, a clinically insignificant amount of labral pathology was present before injury, but without a preinjury MRI scan, this cannot be determined.

A small number of studies have shown promising results of surgical management in cases of batter's shoulder with isolated posterior labral tears, with most patients returning to play.^4-6 Wanich et al⁶ published a case series of high-level athletes with batter's shoulder, for which 10 underwent arthroscopic repair and two received débridement alone, with 11 of the 12 athletes returning to previous levels of play at an average of 5.9 months. OKeefe et al published a retrospective cohort study of five collegiate players with batter's shoulder who underwent arthroscopic repair. All patients regained preoperative ROM and strength at 6 months and returned to previous levels of play.⁵ Kercher et al published a retrospective cohort study of 32 cases of posterior labral repair in baseball athletes at all levels of play, of which 8 cases were a result of batter's shoulder. Overall, 94% of patients returned to play, with 61% of these patients achieving previous levels of play, and position players had higher rates of return to previous levels of play compared with pitchers.⁴

Other studies examining SLAP repair among overhead athletes and baseball players show that return-to-play data varies from approximately 30% to 80%, substantially more variable compared with the limited data available regarding batter's shoulder.^{14,15,16,17,18} Douglas et al¹⁹ found after repair of isolated type II or greater SLAP tears, controlling for concomitant shoulder injuries, position players compared with pitchers displayed a higher return to play (91.3% versus 80.0%) and return to previous or higher levels of play (78.3% versus 52.3%). Debate exists, however, because other studies have shown equivalent return to play for pitchers versus position players after SLAP repair.^16,20

Finally, the postoperative rehabilitation protocol at our institution ultimately focused on dedicated lead shoulder sport-specific function after a routine period of shoulder protection and regain of full shoulder ROM. Rehabilitation needs to address a variety of scapulothoracic and glenohumeral conditioning exercise programs, with an emphasis on external rotation strength, stabilization, and control.^5,21

Conclusion

This patient's outcome as a positional player sustaining an atypical batter's shoulder injury is consistent with the return-to-play data available in the literature.^5,6,19 In understanding the complexity of the shoulder during the batter's swing, this report further characterizes batter's shoulder and demonstrates a positive prognosis after surgical repair.