title: Suprapectoral or subpectoral position for biceps tenodesis: biomechanical comparison of four different techniques in both positions.
abstract: OBJECTIVE
  The aim of this study was to compare different techniques for tenodesis of the long head of biceps tendon (LHB) in the suprapectoral and subpectoral position to test the hypothesis that using shorter screws at the subpectoral position would achieve a similar primary ultimate failure load (UFL) as the longer screws at the suprapectoral position, that both types of tenodesis screws achieve comparable UFL, and that knotless suture anchor techniques can be performed at the subpectoral position in cortical bone and reach a UFL similar to tenodesis screws.
  
  
  METHODS
  On 42 fresh frozen human cadavers divided into 6 groups, 4 different techniques for LHB tenodesis were performed localized 10 mm and 50 mm, respectively, distal to the entrance of the bicipital groove. Two techniques with tenodesis screws (Bio-Tenodesis screw, Biceptor) and 2 with knotless suture anchors (Bio-SwiveLock, Footprint PK) were tested. Under a 10-N preload, an axial cyclic load with 100 cycles, 1-Hz frequency, and 50-N maximal load was applied. UFL was evaluated with an axial traction of 0.2 mm/s until decrease of tension. LHB dislocation was measured by 3-dimensional photogrammetry.
  
  
  RESULTS
  All techniques except the subpectoral Bio-SwiveLock had a dislocation <3 mm after cyclic loading. The highest mean UFL was measured for the suprapectoral Bio-Tenodesis screw (218.3 ± 59.7 N) and the lowest with the subpectoral Footprint PK (99.1 ± 16.4 N). The UFL of suture anchors were significantly lower than those of interference screws (P < .01). UFL was not significantly different for type of interference screw, the type of suture anchor, or tenodesis localization. Different failure mechanisms were evaluated for suture anchors and interference screws.
  
  
  CONCLUSIONS
  Due to the biomechanical testings interference screws are appropriate devices for suprapectoral and subpectoral biceps tenodesis resisting cyclic loading and attaining a satisfactory, whereas the knotless suture anchors sustained a significant about 50% lower UFL, and can only be recommended conditionally for LHB tenodesis regarding primary stability.
authors.affiliation: Department of Orthopaedics, University Hospital of Duesseldorf, Duesseldorf, Germany. th.patzer@web.de
authors.forename: Thilo
authors.initials: T
authors.lastname: Patzer
authors.forename: Gerwin
authors.initials: G
authors.lastname: Santo
authors.forename: Gavin D
authors.initials: GD
authors.lastname: Olender
authors.forename: Mathias
authors.initials: M
authors.lastname: Wellmann
authors.forename: Christof
authors.initials: C
authors.lastname: Hurschler
authors.forename: Markus D
authors.initials: MD
authors.lastname: Schofer
mesh_terms: D000328:Adult; D000368:Aged; D001696:Biomechanical Phenomena; D001863:Bone Screws; D002102:Cadaver; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010780:Photogrammetry; D011474:Prosthesis Design; D017006:Rotator Cuff / Q000503:physiopathology / Q000601:surgery*; D053441:Suture Anchors; D013536:Suture Techniques / Q000295:instrumentation*; D013708:Tendon Injuries / Q000503:physiopathology / Q000601:surgery*; D053656:Tenodesis / Q000379:methods*