title: The dimensional accuracy for preparation of the femoral cavity in HIP arthroplasty. A comparison between manual- and robot-assisted implantation of hip endoprosthesis stems in cadaver femurs.
abstract: BACKGROUND
  The aim of the study was to determine the precision of the preparation of the femoral cavity in cementless hip arthroplasty. We compared the bone-prosthesis interface after manual- and robot-assisted implantation of the stems.
  
  
  METHODS
  After plastination the specimens were cut to slices of 2.5 mm and documented by microradiography. The interface between prosthesis and bone was measured digitally with a specially designed software.
  
  
  RESULTS
  The manually implanted prostheses showed an average full-contact area of 60% and an average area of gaps of 40% with an average height of 0.8 mm. The robot-assisted implanted stems had a significantly higher bone-prosthesis interface area of 93% and gap areas of less than 0.2 mm depth. Destructions of the spongeous bone were seen with the manually implanted stems but not after robot-assisted implantations. There was one stem fracture during the manual preparation of a stem. Microradiographic examination showed microfractures in the region of the lesser trochanter in two femora after robot-assisted implantation
  
  
  CONCLUSIONS
  The robot-assisted technique highly increased the fitting area at the bone-prosthesis interface. The main reason for the fractures might be the absence of a robot done marker for the ideal implantation height with the applied type of prosthesis.
authors.affiliation: Clinic for Orthopaedic Surgery, University-Clinicum Schleswig-Holstein, Campus Kiel, Michaelisstreet 1, 24105, Kiel, Germany. drprymka@hotmail.com
authors.forename: Marcel
authors.initials: M
authors.lastname: Prymka
authors.forename: Lidong
authors.initials: L
authors.lastname: Wu
authors.forename: Hans-Jürgen
authors.initials: HJ
authors.lastname: Hahne
authors.forename: Jürgen
authors.initials: J
authors.lastname: Koebke
authors.forename: Joachim
authors.initials: J
authors.lastname: Hassenpflug
mesh_terms: D019644:Arthroplasty, Replacement, Hip / Q000295:instrumentation / Q000379:methods*; D002102:Cadaver; D019544:Equipment Failure Analysis; D005269:Femur / Q000601:surgery*; D006622:Hip Prosthesis; D015203:Reproducibility of Results; D012371:Robotics / Q000295:instrumentation / Q000379:methods*; D025321:Surgery, Computer-Assisted / Q000295:instrumentation / Q000379:methods*