title: Effect of the starting point of half-pin insertion on the insertional torque of the pin at the tibia.
abstract: OBJECTIVE
  The authors have observed a failure to achieve secure fixation in elderly patients when inserting a half-pin at the anteromedial surface of the tibia. The purpose of this study was to compare two methods for inserting a half-pin at tibia diaphysis in elderly patients.
  
  
  METHODS
  Twenty cadaveric tibias were divided into Group C or V. A half-pin was inserted into the tibias of Group C via the conventional method, from the anteromedial surface to the interosseous border of the tibia diaphysis, and into the tibias of Group V via the vertical method, from the anterior border to the posterior surface at the same level. The maximum insertion torque was measured during the bicortical insertion with a torque driver. The thickness of the cortex was measured by micro-computed tomography. The relationship between the thickness of the cortex engaged and the insertion torque was investigated.
  
  
  RESULTS
  The maximum insertion torque and the thickness of the cortex were significantly higher in Group V than Group C. Both groups exhibited a statistically significant linear correlation between torque and thickness by Spearman's rank correlation analysis.
  
  
  CONCLUSIONS
  Half-pins inserted by the vertical method achieved purchase of more cortex than those inserted by the conventional method. Considering that cortical thickness and insertion torque in Group V were significantly greater than those in Group C, we suggest that the vertical method of half-pin insertion may be an alternative to the conventional method in elderly patients.
authors.affiliation: Department of Orthopaedic Surgery, Arthroscopy and Joint Research Institute, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Sung Jae
authors.initials: SJ
authors.lastname: Kim
authors.affiliation: Department of Orthopaedic Surgery, Arthroscopy and Joint Research Institute, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Sung Hwan
authors.initials: SH
authors.lastname: Kim
authors.affiliation: Department of Orthopaedic Surgery, Arthroscopy and Joint Research Institute, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Young Hwan
authors.initials: YH
authors.lastname: Kim
authors.affiliation: Department of Orthopaedic Surgery, Arthroscopy and Joint Research Institute, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea. min1201@hanmail.net.
authors.forename: Yong Min
authors.initials: YM
authors.lastname: Chun
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001858:Bone Nails; D001863:Bone Screws; D018483:Diaphyses / Q000000981:diagnostic imaging / Q000601:surgery; D016267:External Fixators; D005260:Female; D006801:Humans; D008297:Male; D013977:Tibia / Q000000981:diagnostic imaging / Q000601:surgery*; D019415:Torque; D055114:X-Ray Microtomography
keywords: Fracture; diaphysis; external fixation; tibia