title: Biomechanical in vitro validation of intramedullary cortical button fixation for distal biceps tendon repair: a new technique.
abstract: BACKGROUND
  Extramedullary cortical button-based fixation for distal biceps tendon ruptures exhibits maximum load to failure in vitro but cannot restore the anatomic footprint and has the potential risk for injury to the posterior interosseous nerve.
  
  
  OBJECTIVE
  Double intramedullary cortical button fixation repair provides superior fixation strength to the bone when compared with single extramedullary cortical button-based repair.
  
  
  METHODS
  Controlled laboratory study.
  
  
  METHODS
  The technique of intramedullary cortical button fixation with 1 or 2 buttons was compared with single extramedullary cortical button-based repair using 12 paired human cadaveric elbows. All specimens underwent computed tomography analysis to determine intramedullary dimensions of the radial tuberosity as well as the thickness of the anterior and posterior cortices before biomechanical testing. Maximum load to failure and failure modes were recorded. For baseline measurements, the native tendon was tested for maximum load to failure.
  
  
  RESULTS
  The intramedullary area of the radial tuberosity provides sufficient space for single or double intramedullary cortical button implantation. The mean thickness of the anterior cortex was 1.13 ± 0.15 mm, and for the posterior cortex it was 1.97 ± 0.48 mm (P < .001). We found the highest loads to failure for double intramedullary cortical button fixation with a mean load to failure of 455 ± 103 N, versus 275 ± 44 N for single intramedullary cortical button fixation (P < .001) and 305 ± 27 N for single extramedullary cortical button-based technique (P = .003). There were no statistically significant differences between single intramedullary and single extramedullary button fixation repair (P = .081). The mean load to failure for the native tendon was 379 ± 87 N.
  
  
  CONCLUSIONS
  Double intramedullary cortical button fixation provides the highest load to failure in the specimens tested.
  
  
  CONCLUSIONS
  Double intramedullary cortical button fixation provides reliable fixation strength to the bone for distal biceps tendon repair and potentially minimizes the risk of posterior interosseous nerve injury. Further, based on a 2-point-fixation, this method may offer a wider, more anatomic restoration of the distal biceps tendon to its anatomic footprint.
authors: Department of Trauma Surgery, Klinikum rechts der Isar, Technical University Munich, Munich, Germany. siebenlist@uchir.me.tum.de
authors: Sebastian
authors: S
authors: Siebenlist
authors: Andreas
authors: A
authors: Lenich
authors: Arne
authors: A
authors: Buchholz
authors: Frank
authors: F
authors: Martetschläger
authors: Stefan
authors: S
authors: Eichhorn
authors: Petra
authors: P
authors: Heinrich
authors: Alexander
authors: A
authors: Fingerle
authors: Stefan
authors: S
authors: Doebele
authors: Gunther H
authors: GH
authors: Sandmann
authors: Peter J
authors: PJ
authors: Millett
authors: Ulrich
authors: U
authors: Stöckle
authors: Florian
authors: F
authors: Elser
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001134:Arm Injuries / Q000000981:diagnostic imaging / Q000601:surgery*; D001696:Biomechanical Phenomena; D006801:Humans; D013708:Tendon Injuries / Q000000981:diagnostic imaging / Q000601:surgery*; D053656:Tenodesis / Q000379:methods*; D014057:Tomography, X-Ray Computed