title: Broach Handle Design Changes Force Distribution in the Femur During Total Hip Arthroplasty.
abstract: Curved broach handles were developed to overcome limited surgical exposures during total hip arthroplasty. Some authors report increased intraoperative fracture rates during limited exposures. This study evaluates mechanical force ratios transmitted to the bone while broaching with curved vs straight handles.
  
  
  
  An experimental model utilized a 6-axis load cell to measure force distributions produced by 4 different broach handles, each with increasing offset and curvature. Handles were separately impacted and dynamic variables assessed. Handles were then digitized using a high-resolution optical system and a finite element analysis (FEA) was performed to account for trabecular bone and vary the location of mallet impact. Off-axis forces, broaching construct moments, and stress within surrounding bone were computed.
  
  
  
  Using the experimental model, high-offset handles lost on average 4% more hammering force to the horizontal axis. When the FEA utilized moduli of elasticity to estimate broaching through osteoporotic trabecular bone, horizontally displaced forces (toward cortical bone) were magnified from 4% to a maximum value of 52%. Both the experimental construct and FEA confirmed that larger offset handles increase moment-to-force ratios up to 163%-235%, thus rotating the proximal and distal ends of the broach toward cortical bone.
  
  
  
  Broach handle design is an important determinant of resultant forces transmitted to the broach (and ultimately the bone) during total hip arthroplasty. Unwanted off-axis forces and enhanced rotational dynamics may play a role in intraoperative fractures during femoral canal preparation.
authors.affiliation: Department of Orthopaedic Surgery & Sports Medicine, Temple University Hospital, Philadelphia, Pennsylvania.
authors.forename: Dustin A
authors.initials: DA
authors.lastname: Greenhill
authors.affiliation: Department of Mechanical Engineering, Temple University, Philadelphia, Pennsylvania.
authors.forename: Pooyan
authors.initials: P
authors.lastname: Abbasi
authors.affiliation: Department of Mechanical Engineering, Temple University, Philadelphia, Pennsylvania.
authors.forename: Kurosh
authors.initials: K
authors.lastname: Darvish
authors.affiliation: Division of Orthopaedic Surgery, Rothman Institute at Abington-Jefferson Health, Willow Grove, Pennsylvania.
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Star
mesh_terms: D019644:Arthroplasty, Replacement, Hip / Q000295:instrumentation* / Q000379:methods*; D004548:Elasticity; D004867:Equipment Design; D005269:Femur / Q000601:surgery*; D020342:Finite Element Analysis; D006801:Humans; D007432:Intraoperative Period; D055595:Mechanical Phenomena; D008962:Models, Theoretical; D011183:Postoperative Complications; D013314:Stress, Mechanical; D013525:Surgical Instruments
keywords: broach offset; direct anterior hip arthroplasty; femoral canal preparation; finite element analysis; iatrogenic fracture