title: Impact magnitudes applied by surgeons and their importance when applying the femoral head onto the Morse taper for total hip arthroplasty.
abstract: BACKGROUND
  This study was designed to test whether the number of impacts, the experience of the surgeon or impact force made significant difference in pull off forces.
  
  
  METHODS
  The forces applied by 10 orthopaedic surgeons (five residents and five attending staff) to impact the femoral head onto the trunnion of a femoral component were recorded. The resultant forces were then divided into four energy levels and compared to determine if the number of impacts would make a difference in pull off strength.
  
  
  RESULTS
  No significant differences existed between the resident versus attending groups in magnitude of force applied. Through ANOVA testing, it was found that at each of the energy levels, multiple blows demonstrated a significant pull off strength difference compared to a single blow. Increased pull off force was also noted when the magnitude of force of the applied blows was increased.
  
  
  CONCLUSIONS
  We recommend at least two firm, axially aligned blows to impact the femoral head onto the trunnion intra-operatively.
authors.affiliation: Department of Orthopaedics, ProMedica Health System, Harris McIntosh Tower, Toledo, OH 43606, USA. jakeheiney@ameritech.net
authors.forename: Jake P
authors.initials: JP
authors.lastname: Heiney
authors.forename: Suneel
authors.initials: S
authors.lastname: Battula
authors.forename: Gregory A
authors.initials: GA
authors.lastname: Vrabec
authors.forename: Anand
authors.initials: A
authors.lastname: Parikh
authors.forename: Rebecca
authors.initials: R
authors.lastname: Blice
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Schoenfeld
authors.forename: Glenn O
authors.initials: GO
authors.lastname: Njus
mesh_terms: D019644:Arthroplasty, Replacement, Hip / Q000379:methods*; D001696:Biomechanical Phenomena; D002983:Clinical Competence; D019544:Equipment Failure Analysis / Q000379:methods*; D005270:Femur Head / Q000601:surgery*; D006622:Hip Prosthesis; D006801:Humans; D007396:Internship and Residency; D009985:Orthopedics / Q000193:education; D011474:Prosthesis Design; D012307:Risk Factors