title: Risk of axillary nerve injury during percutaneous proximal humerus locking plate insertion using an external aiming guide.
abstract: OBJECTIVE
  The purpose of this study was to determine which screws could be safely inserted percutaneously into a proximal humerus locking plate using a new external aiming guide without injuring the axillary nerve. We also sought to evaluate that all the screws could be accurately inserted ina locked position with the external guide.
  
  
  METHODS
  Eight cadaveric specimens were implanted with a proximal humerus locking plate using a minimally invasive direct-lateral deltoid splitting approach using an attached external aiming guide for screw insertion. The anatomic proximity of the axillary nerve to the guidewires and screws was measured following soft tissue dissection and inspection of the nerve.
  
  
  RESULTS
  The two superior holes (C1 and C2) were proximal to the axillary nerve with an average distance of 15.1 mm. Screw F was on average 6.6 mm distal to the axillary nerve but within 2 mm of the nerve in two specimens. In all specimens, the locking screws were appropriately seated in a locked position using the external aiming guide.
  
  
  CONCLUSIONS
  This study suggests that percutaneous fixation of a proximal humerus locking plate with an external aiming guide can be safely used for proximal humerus fractures. The limited number of screws that can be inserted into the proximal fragment using the current external guide arm may compromise fixation of more unstable fractures. Therefore, the indications for percutaneous locking plate fixation of the proximal humerus using an external aiming guide should be limited to stable fracture patterns that can be anatomically reduced.
authors.affiliation: Division of Orthopaedic Surgery, Montreal General Hospital, McGill University Health Centre, 1650 Cedar Avenue Room L9.416, Montreal, Quebec H3G 1A4, Canada.
authors.forename: Neil
authors.initials: N
authors.lastname: Saran
authors.forename: Stephane G
authors.initials: SG
authors.lastname: Bergeron
authors.forename: Benoit
authors.initials: B
authors.lastname: Benoit
authors.forename: Rudolf
authors.initials: R
authors.lastname: Reindl
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Harvey
authors.forename: Gregory K
authors.initials: GK
authors.lastname: Berry
mesh_terms: D001365:Axilla / Q000294:innervation; D001860:Bone Plates; D001863:Bone Screws; D002102:Cadaver; D005240:Feasibility Studies; D005593:Fracture Fixation, Internal / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D059348:Peripheral Nerve Injuries; D010525:Peripheral Nerves / Q000033:anatomy & histology; D018570:Risk Assessment; D012784:Shoulder Fractures / Q000601:surgery*