title: Remplissage of an Off-track Hill-Sachs Lesion Is Necessary to Restore Biomechanical Glenohumeral Joint Stability in a Bipolar Bone Loss Model.
abstract: To validate the glenoid track concept in a cadaveric bipolar bone loss model and to test whether "on-track" and "off-track" lesions can be stabilized with Bankart repair (BR) with or without Hill-Sachs remplissage (HSR).
  
  
  
  Eight fresh-frozen cadaveric shoulders were tested in a custom apparatus with passive axial rotation and then progressive translational loading (10 to 40 N) at mid-range (60°) and end-range external rotation (90°). Injury conditions included glenoid bone loss of 15% with on-track (15%) and off-track (30%) Hill-Sachs lesions. Repair conditions included BR with HSR and BR without HSR.
  
  
  
  For on-track lesions, engagement occurred with translation testing in one shoulder (12.5%) at end-range rotation. After BR, engagement was prevented for this shoulder. For off-track lesions, engagement with translation testing occurred in 8 shoulders (100%) at end-range rotation and in 6 (75%) at mid-range rotation. After BR, engagement was prevented in 4 of 6 engaging shoulders (67%) at mid-range rotation but was prevented in zero of 8 (0%) at end-range rotation. Adding HSR prevented engagement in all 14 engaging shoulders with off-track lesions (100%). BR with HSR resulted in supraphysiological stiffness for off-track lesions at mid- and end-range rotation (13.3 N/m vs 7.0 N/m and 10.0 N/m vs 5.0 N/m, P = .0002) and for on-track lesions at end-range rotation (10.1 N/m vs 5.0 N/m, P = .0002). Stiffness of BR with HSR was not different from the intact shoulder for on-track lesions at mid-range rotation (7.2 N/m vs 7.0 N/m, P > .99).
  
  
  
  The patterns of engagement of Hill-Sachs lesions with a 15% glenoid defect in this model give support to the glenoid track concept. BR plus remplissage resulted in supraphysiological shoulder stiffness but was necessary to prevent engagement of off-track bipolar bone lesions.
  
  
  
  This biomechanical study provides evidence to aid in surgical decision making by examining the effects of bipolar bone loss and soft-tissue reconstruction on shoulder stability.
authors.affiliation: Burkhart Research Institute for Orthopaedics and The San Antonio Orthopaedic Group, San Antonio, Texas, U.S.A.
authors.forename: Robert U
authors.initials: RU
authors.lastname: Hartzler
authors.affiliation: Orthopaedic Biomechanics Laboratory, VA Long Beach Healthcare System, and University of California, Irvine, Irvine, California, U.S.A.
authors.forename: Christopher N H
authors.initials: CN
authors.lastname: Bui
authors.affiliation: Orthopaedic Biomechanics Laboratory, VA Long Beach Healthcare System, and University of California, Irvine, Irvine, California, U.S.A.
authors.forename: Woong K
authors.initials: WK
authors.lastname: Jeong
authors.affiliation: Orthopaedic Biomechanics Laboratory, VA Long Beach Healthcare System, and University of California, Irvine, Irvine, California, U.S.A.
authors.forename: Masaki
authors.initials: M
authors.lastname: Akeda
authors.affiliation: Orthopaedic Biomechanics Laboratory, VA Long Beach Healthcare System, and University of California, Irvine, Irvine, California, U.S.A.
authors.forename: Alex
authors.initials: A
authors.lastname: Peterson
authors.affiliation: Orthopaedic Biomechanics Laboratory, VA Long Beach Healthcare System, and University of California, Irvine, Irvine, California, U.S.A.
authors.forename: Michelle
authors.initials: M
authors.lastname: McGarry
authors.affiliation: Southern Oregon Orthopedics, Medford, Oregon, U.S.A.
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Denard
authors.affiliation: Burkhart Research Institute for Orthopaedics and The San Antonio Orthopaedic Group, San Antonio, Texas, U.S.A.. Electronic address: gruelas@tsaog.com.
authors.forename: Stephen S
authors.initials: SS
authors.lastname: Burkhart
authors.affiliation: Orthopaedic Biomechanics Laboratory, VA Long Beach Healthcare System, and University of California, Irvine, Irvine, California, U.S.A.
authors.forename: Thay Q
authors.initials: TQ
authors.lastname: Lee
mesh_terms: D001182:Arthroscopy / Q000379:methods*; D000070896:Bankart Lesions / Q000503:physiopathology / Q000601:surgery*; D001696:Biomechanical Phenomena / Q000502:physiology; D002102:Cadaver; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000503:physiopathology / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D010014:Osteolysis / Q000503:physiopathology*; D012785:Shoulder Joint / Q000503:physiopathology*; D053441:Suture Anchors