title: Volar percutaneous screw fixation of the scaphoid: a cadaveric study.
abstract: OBJECTIVE
  To test the efficacy of a previously described technique of angiocatheter-assisted instrument positioning in achieving a central screw position in a cadaveric model for volar percutaneous screw fixation (PSF) of the scaphoid and to quantify the damage to surrounding soft tissue and articular cartilage associated with the procedure.
  
  
  METHODS
  We performed fluoroscopically guided volar PSF of the scaphoid on 10 fresh cadaveric wrists. We then dissected the specimens, analyzed screw position in cross sections of the scaphoid, and described injury to nearby soft tissue structures as well as articular cartilage of the scaphotrapezial joint.
  
  
  RESULTS
  All 10 screws were positioned within the central third of the scaphoid on at least 2 of 3 cross sections, and 8 of 10 screws were positioned within the central third of the proximal pole. Two wrists required a transtrapezial trajectory for satisfactory screw positioning. None of the specimens sustained visible neurovascular damage, and 2 wrists revealed minor tendon damage. Trajectories involving the scaphotrapezial joint violated, on average, 7% of the scaphoid articular cartilage. With a transtrapezial trajectory, 11% of the trapezial cartilage was violated
  
  
  CONCLUSIONS
  Central positioning of the screw is biomechanically superior, and screw position within the central one third of the proximal pole has been associated with faster time to union. Volar PSF achieved satisfactory screw position in the scaphoid. The majority of wrists were amenable to PSF via the scaphotrapezial joint, though a transtrapezial approach was a viable alternative for wrists with restrictive anatomy. Both approaches minimally disrupted the scaphotrapezial joint and surrounding soft tissues.
  
  
  METHODS
  Therapeutic IV.
authors.affiliation: Department of Orthopaedic Surgery and the Division of Plastic Surgery, Los Angeles County and University of Southern California Medical Center, Keck School of Medicine of University of Southern California, Los Angeles, CA. Electronic address: Maksim.Vaynrub@med.usc.edu.
authors.forename: Max
authors.initials: M
authors.lastname: Vaynrub
authors.affiliation: Department of Orthopaedic Surgery and the Division of Plastic Surgery, Los Angeles County and University of Southern California Medical Center, Keck School of Medicine of University of Southern California, Los Angeles, CA.
authors.forename: Joseph N
authors.initials: JN
authors.lastname: Carey
authors.affiliation: Department of Orthopaedic Surgery and the Division of Plastic Surgery, Los Angeles County and University of Southern California Medical Center, Keck School of Medicine of University of Southern California, Los Angeles, CA.
authors.forename: Milan V
authors.initials: MV
authors.lastname: Stevanovic
authors.affiliation: Department of Orthopaedic Surgery and the Division of Plastic Surgery, Los Angeles County and University of Southern California Medical Center, Keck School of Medicine of University of Southern California, Los Angeles, CA.
authors.forename: Alidad
authors.initials: A
authors.lastname: Ghiassi
mesh_terms: D001863:Bone Screws; D002102:Cadaver; D005471:Fluoroscopy; D005593:Fracture Fixation, Internal / Q000295:instrumentation*; D050723:Fractures, Bone / Q000601:surgery*; D006801:Humans; D021361:Scaphoid Bone / Q000293:injuries*
keywords: Percutaneous screw fixation; scaphoid fracture; volar approach