title: Biomechanical evaluation of a unicortical button versus interference screw for subpectoral biceps tenodesis.
abstract: OBJECTIVE
  The purpose of this study was to evaluate and compare the biomechanical properties of a unicortical button with an interference screw used for subpectoral biceps tenodesis. We also describe the anatomic dangers of bicortical button use in the subpectoral location.
  
  
  METHODS
  Twenty-eight fresh-frozen human cadaveric shoulders with a mean age of 52 years were studied. The specimens were randomly divided into 4 experimental biceps tenodesis groups (n = 7): unicortical button, interference screw, bicortical suspensory button, and bicortical suspensory with interference screw (Arthrex, Naples, FL). Each tenodesis specimen was mounted on a mechanical testing machine, preloaded for 2 minutes at 5 N, cycled from 5 to 70 N for 500 cycles (1 Hz), and loaded to failure (1 mm/s). We determined the mode of failure and computed the ultimate load to failure, yield load, pullout stiffness, and displacement at peak load. Calculations of the distance between the axillary and radial nerves with respect to the bicortical buttons were also calculated in 6 specimens.
  
  
  RESULTS
  There was no statistically significant difference (P > .05) among groups in terms of age, ultimate load to failure, pullout stiffness, or displacement at peak load. Suture-tendon interface failure was the most commonly observed mode of failure. The axillary nerve was on average 7.8 mm from the bicortical button; however, in 6 specimens the nerve was less than 3 mm away.
  
  
  CONCLUSIONS
  The use of a unicortical button for subpectoral biceps tenodesis provides biomechanical properties similar to the use of an interference screw. In addition, the use of a bicortical button in this area of the proximal humerus puts the axillary nerve at risk.
  
  
  CONCLUSIONS
  Using a unicortical button subpectoral biceps method may provide a surgeon with a safe and technically easy and reproducible technique while providing similar biomechanical properties to a known standard implant.
authors: Department of Orthopaedics, Sharp Rees-Stealy Medical Center, San Diego, California, USA. amarpal0677@yahoo.com
authors: Amarpal S
authors: AS
authors: Arora
authors: Anshu
authors: A
authors: Singh
authors: Ryan C
authors: RC
authors: Koonce
mesh_terms: D001696:Biomechanical Phenomena; D001863:Bone Screws; D002102:Cadaver; D006801:Humans; D008875:Middle Aged; D053441:Suture Anchors; D013710:Tendons / Q000503:physiopathology / Q000601:surgery*; D053656:Tenodesis / Q000295:instrumentation*