Decreased Trunk Rotation at Foot Contact in Professional Baseball Pitchers With Prior Conservatively Managed SLAP Tears: A Propensity Score–Matched Analysis

Published:November 13, 2021DOI:


      To compare kinematic and kinetic parameters between a cohort of fully recovered professional pitchers with prior shoulder injury treated conservatively and a cohort with no prior shoulder injury.


      Twenty-six fully recovered professional baseball pitchers with a history of shoulder injury treated conservatively pitched 8 to 10 fastball pitches using 3-dimensional motion capture (480 Hz). All shoulder injuries occurred within a 1- to 4-year time span from biomechanical evaluation and were severe enough to prevent pitchers from playing for between 1 and 12 months. These pitchers were propensity score matched by age, height, weight, handedness, and ball velocity to pitchers with no prior injury history (control) at a ratio of 1:4. We compared 21 kinematic and 11 kinetic parameters between groups using appropriate parametric testing. Subanalysis comparisons of pitchers with prior SLAP injury as well as rotator cuff tendinitis were also performed.


      SLAP tears (n = 11, 42.3%) were the most frequently reported injury, followed by rotator cuff tendinitis and/or shoulder impingement (n = 7, 26.9%). Compared with the control group, the 26 pitchers with prior injury showed no significant differences across the kinematic and kinetic factors. However, the SLAP tear subgroup did show significantly less trunk rotation at foot contact compared with controls (34.1° ± 4.9° vs 39.2° ± 10.2°, P = .0075).


      Fully recovered professional baseball pitchers with shoulder injuries treated conservatively showed no significant differences in kinetics or kinematics compared with their propensity score–matched counterparts, suggesting that shoulder injury alone may not greatly alter pitching mechanics. However, whereas prior groups have shown a decrease in trunk rotation at foot contact after surgical repair for SLAP tears, our study suggests that this kinematic change may alternatively originate with the injury itself.

      Clinical Relevance

      Understanding the cause of biomechanical adaptations by pitchers after injury can better aid clinicians and coaching staff in providing individualized and specific care to the throwing athlete.
      To read this article in full you will need to make a payment

      Purchase one-time access:

      Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online access
      One-time access price info
      • For academic or personal research use, select 'Academic and Personal'
      • For corporate R&D use, select 'Corporate R&D Professionals'


      Subscribe to Arthroscopy
      Already a print subscriber? Claim online access
      Already an online subscriber? Sign in
      Institutional Access: Sign in to ScienceDirect


        • Posner M.
        • Cameron K.L.
        • Wolf J.M.
        • Belmont P.J.
        • Owens B.D.
        Epidemiology of Major League Baseball injuries.
        Am J Sports Med. 2011; 39: 1675-1691
        • Conte S.
        • Camp C.L.
        • Dines J.S.
        Injury trends in Major League Baseball over 18 seasons: 1998-2015.
        Am J Orthop (Belle Mead NJ). 2016; 45: 116-123
        • Camp C.L.
        • Dines J.S.
        • van der List J.P.
        • et al.
        Summative report on time out of play for Major and Minor League Baseball: An analysis of 49,955 injuries from 2011 through 2016.
        Am J Sports Med. 2018; 46: 1727-1732
        • Conte S.
        • Requa R.K.
        • Garrick J.G.
        Disability days in Major League Baseball.
        Am J Sports Med. 2001; 29: 431-436
        • Makhni E.C.
        • Buza J.A.
        • Byram I.
        • Ahmad C.S.
        Sports reporting: A comprehensive review of the medical literature regarding North American professional sports.
        Phys Sportsmed. 2014; 42: 154-162
        • Edwards S.L.
        • Lee J.A.
        • Bell J.E.
        • et al.
        Nonoperative treatment of superior labrum anterior posterior tears: Improvements in pain, function, and quality of life.
        Am J Sports Med. 2010; 38: 1458-1461
        • Chalmers P.N.
        • Erickson B.J.
        • D’Angelo J.
        • Ma K.
        • Romeo A.A.
        Epidemiology of shoulder surgery among professional baseball players.
        Am J Sports Med. 2019; 47: 1068-1073
        • Fleisig G.S.
        • Leddon C.E.
        • Laughlin W.A.
        • et al.
        Biomechanical performance of baseball pitchers with a history of ulnar collateral ligament reconstruction.
        Am J Sports Med. 2015; 43: 1045-1050
        • Laughlin W.A.
        • Fleisig G.S.
        • Scillia A.J.
        • Aune K.T.
        • Cain E.L.
        • Dugas J.R.
        Deficiencies in pitching biomechanics in baseball players with a history of superior labrum anterior-posterior repair.
        Am J Sports Med. 2014; 42: 2837-2841
        • Chalmers P.N.
        • Trombley R.
        • Cip J.
        • et al.
        Postoperative restoration of upper extremity motion and neuromuscular control during the overhand pitch: Evaluation of tenodesis and repair for superior labral anterior-posterior tears.
        Am J Sports Med. 2014; 42: 2825-2836
        • Aguinaldo A.L.
        • Buttermore J.
        • Chambers H.
        Effects of upper trunk rotation on shoulder joint torque among baseball pitchers of various levels.
        J Appl Biomech. 2007; 23: 42-51
        • Wilk K.E.
        • Macrina L.C.
        • Cain E.L.
        • Dugas J.R.
        • Andrews J.R.
        The recognition and treatment of superior labral (SLAP) lesions in the overhead athlete.
        Int J Sports Phys Ther. 2013; 8: 579-600
        • Chalmers P.N.
        • Erickson B.J.
        • Ball B.
        • Romeo A.A.
        • Verma N.N.
        Fastball pitch velocity helps predict ulnar collateral ligament reconstruction in Major League Baseball pitchers.
        Am J Sports Med. 2016; 44: 2130-2135
        • Luera M.J.
        • Dowling B.
        • Magrini M.A.
        • Muddle T.W.D.
        • Colquhoun R.J.
        • Jenkins N.D.M.
        Role of rotational kinematics in minimizing elbow varus torques for professional versus high school pitchers.
        Orthop J Sport Med. 2018; 6 (232596711876078)
        • Luera M.J.
        • Dowling B.
        • Muddle T.W.D.
        • Jenkins N.D.M.
        Differences in rotational kinetics and kinematics for professional baseball pitchers with higher versus lower pitch velocities.
        J Appl Biomech. 2020; 36: 68-75
        • Rosenbaum P.R.
        Propensity score.
        in: P. Armitage, T. Colton (eds.) Wiley StatsRef: Statistics reference online. John Wiley & Sons, Hoboken, NJ2015: 1-7
        • Haukoos J.S.
        • Lewis R.J.
        The propensity score.
        JAMA. 2015; 314: 1637-1638
        • Austin P.C.
        Some methods of propensity-score matching had superior performance to others: Results of an empirical investigation and Monte Carlo simulations.
        Biom J. 2009; 51: 171-184
        • Chauhan A.
        • Tam J.H.
        • Porter A.J.
        • et al.
        Professional advancement, performance, and injury characteristics of baseball players entering the Major League Baseball draft after treatment for shoulder injuries.
        J Shoulder Elbow Surg. 2019; 28: 220-226
        • Fortenbaugh D.
        • Fleisig G.S.
        • Andrews J.R.
        Baseball pitching biomechanics in relation to injury risk and performance.
        Sports Health. 2009; 1: 314-320
        • Fleisig G.S.
        • Andrews J.R.
        • Dillman C.J.
        • Escamilla R.F.
        Kinetics of baseball pitching with implications about injury mechanisms.
        Am J Sports Med. 1995; 23: 233-239
      1. Park SS, Loebenberg ML, Rokito A, Zuckerman J. The shoulder in baseball pitching: Biomechanics and related injuries—Part 1. Bull Hosp Jt Dis 2002-2003;61:68-69.

        • Mileski R.A.
        • Snyder S.J.
        Superior labral lesions in the shoulder: Pathoanatomy and surgical management.
        J Am Acad Orthop Surg. 1998; 6: 121-131
        • Burkhart S.S.
        • Morgan C.D.
        • Ben Kibler W.
        The disabled throwing shoulder: Spectrum of pathology part I: Pathoanatomy and biomechanics.
        Arthroscopy. 2003; 19: 404-420
        • Andrews J.R.
        • Carson W.G.
        • McLeod W.D.
        Glenoid labrum tears related to the long head of the biceps.
        Am J Sports Med. 1985; 13: 337-341
        • Burkhart S.S.
        • Morgan C.D.
        The peel-back mechanism: Its role in producing and extending posterior type II SLAP lesions and its effect on SLAP repair rehabilitation.
        Arthroscopy. 1998; 14: 637-640
        • Varacallo M.
        • Tapscott D.C.
        • Mair S.D.
        Superior labrum anterior posterior lesions.
        StatPearls Publishing, Treasure Island, FL2021
        • McCulloch P.C.
        • Andrews W.J.
        • Alexander J.
        • Brekke A.
        • Duwani S.
        • Noble P.
        The effect on external rotation of an anchor placed anterior to the biceps in type 2 SLAP repairs in a cadaveric throwing model.
        Arthroscopy. 2013; 29: 18-24
        • Dun S.
        • Fleisig G.S.
        • Loftice J.
        • Kingsley D.
        • Andrews J.R.
        The relationship between age and baseball pitching kinematics in professional baseball pitchers.
        J Biomech. 2007; 40: 265-270
        • Loftice J.
        • Fleisig G.S.
        • Zheng N.
        • Andrews J.R.
        Biomechanics of the elbow in sports.
        Clin Sports Med. 2004; 23: 519-530
        • Werner S.L.
        • Murray T.A.
        • Hawkins R.J.
        • Gill T.J.
        Relationship between throwing mechanics and elbow valgus in professional baseball pitchers.
        J Shoulder Elbow Surg. 2002; 11: 151-155
        • Keeley D.W.
        • Hackett T.
        • Keirns M.
        • Sabick M.B.
        • Torry M.R.
        A biomechanical analysis of youth pitching mechanics.
        J Pediatr Orthop. 2008; 28: 452-459
        • Aguinaldo A.L.
        • Chambers H.
        Correlation of throwing mechanics with elbow valgus load in adult baseball pitchers.
        Am J Sports Med. 2009; 37: 2043-2048
        • Anz A.W.
        • Bushnell B.D.
        • Griffin L.P.
        • Noonan T.J.
        • Torry M.R.
        • Hawkins R.J.
        Correlation of torque and elbow injury in professional baseball pitchers.
        Am J Sports Med. 2010; 38: 1368-1374