Baseball pitchers who fail nonoperative care for SLAP injuries will undergo a repair if they wish to continue throwing. The injury may occur at ball release as the biceps contracts to resist glenohumeral joint distraction and decelerate elbow extension. The other thought is that injury occurs in late cocking as the result of a “peel back” mechanism when the abducted shoulder externally rotates. Previous research by Shepard et al. published in American Journal of Sports Medicine (AJSM) measured in vitro strength of the biceps-labral complex during the peel back and distal force and concluded that repetitive force in both scenarios likely causes SLAP lesions.

baseball_pitching_motion_2004

Baseball pitching motion 2004“. Licensed under CC BY-SA 3.0 via Wikimedia Commons.

One of the concerns for pitchers after surgery is regaining full shoulder external rotation and horizontal abduction. If too much tension is placed on the glenohumeral ligaments during surgery, regaining motion can be tough. Ironically, external rotation is limited in the early phase of rehab to protect the labral repair which may impair throwing mechanics later on. Appropriate rehab and progression is paramount for long term success.

Laughlin et al. at the ASMI sought out to explore in a labaratory if there are differences in pitchers who underwent a SLAP repair compared to those in age controlled groups without injury.  In a paper published in the Dec. 2014 AJSM, the researchers hypothesized that the SLAP group would exhibit compromised shoulder range of motion and internal range of motion torque during pitching. Of 634 pitchers (collegiate and professional) tested at ASMI from 2000 - 2014, 13 in this group were included in the SLAP group as they had undergone a SLAP repair at least 1 year before their biomechanical testing.

These 13 were assessed at a mean of 22 months following surgery. Fifty-two pitchers with no history of elbow or shoulder repair were selected as controls. Pitchers in the SLAP group were approximately 2 years older than the control group.  For the analysis, 23 markers were attached to the subjects:

  • 4 markers on the hat
  • 1 marker at each acromion process, lateral elbow epicondyle, ulnar styloid, greater trochanter, lateral femoral epicondyle, lateral malleolus and second metatarsal
  • Additional markers were placed at medial elbow epicondyle, forearm, radial styloid, third metacarpal of throwing hand and heel of the lead foot

Following a warm-up period (non-throwing exercises and unspecified number of throws at indoor facility) the participant threw 10 fastballs that were analyzed.

Results

  • Pitchers in the SLAP group had less horizontal abduction at foot contact and less maximum external rotation
  • No difference in internal rotation torque between groups
  • No significant differences in elbow biomechanics between groups
  • Pitchers in the SLAP group did pitch more upright, exhibiting less forward trunk tilt at ball release
  • No other significant differences in stride length, maximum horizontal adduction angle or forward tilt at maximum shoulder internal rotation (follow through)

Practical applications

Returning to pre-injury pitching after a SLAP repair is a challenge with the average rate around 57% (Neri et al. AJSM 2011). Pitching coaches and biomechanists often report pitchers coming back “hold back”, “push the ball” or exhibit decreased stride length.  The decreased trunk tilt in the SLAP group should interest coaches as they emphasize drills to promote optimal trunk tilt at ball release.  One such drill is the towel drill in which the pitcher snaps a towel down toward a coaches hand or other object to encourage proper mechanics.

The inability to return to full throwing at a pre-injury level may also be due to posterior cuff dysfunction/tearing as well.  Keep in mind this study only analyzed pitchers who did make it back to throwing and NOT those who could not return to pre-injury levels.  As such, no failure for return to play can be made based on biomechanics.  In addition, the main limitation of this paper is that biomechanics of the pitchers in the SLAP group were not assessed prior to injury, so it is impossible to know how altered their mechanics actually were following the surgery and that they amy have possessed different biomechanics than the control group when they were healthy.  Other limitations included a relatively small sample size and the fact that the athletes did not have a uniform surgeon or rehab protocol.

The primary takeaways are that surgeons and physical therapists must be concerned with regaining full horizontal aduction and external rotation as the surgical procedure itself can compromise such motion through excessive tensioning of the glenohumeral ligaments with a nonanatomic SLAP repair.  Thus, early motion and aiming to restore full active and passive ER at 90 degrees of abduction is a must to give pitchers the best chance for a full recovery.

In my experience, there is a delicate balance early on between protecting the repair and avoiding stiffness.  Communication with the MD is paramount as is early awareness and detection of motion restriction.  Having the ability to assess motion prior to surgery would be ideal.  Meanwhile, pitching coaches should look for improper trunk tilt following rehab and address this to maximize throwing motion.  Keep in mind that athletes must also conquer any fear of re-injury upon return to throwing and this will simply take time and repetition.

Article reference: Laughlin et al. Deficiencies in pitching biomechanics in baseball players with a history of superior labrum anterior-posterior repair. Am J Sports Med. 2014 Dec;42(12):2837-41

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