title: Stress-related femoral cortical and cancellous bone density loss after collum femoris preserving uncemented total hip arthroplasty: a prospective 7-year follow-up with quantitative computed tomography.
abstract: OBJECTIVE
  Bone loss around uncemented femoral components is suspected to precede implant loosening and contribute to problems in revision surgery. Short-stemmed cementless femoral components are designed to preserve proximal femoral bone stock and ultimately the longevity of the prosthesis.
  
  
  METHODS
  With quantitative computed tomography-assisted osteodensitometry, we prospectively analyzed femoral cortical and cancellous bone density (BD) and contact area changes of an uncemented collum femoris preserving stem (n = 38) 10 days, 1, 3 and 7 years post-operatively.
  
  
  RESULTS
  Seven years post-operatively, cancellous BD (mg CaHA/mL) had decreased by as much as -66 % and cortical BD by up to -27 % at the metaphyseal portion of the femur; the decrease was progressive between the 1- and 3-year examinations and halted thereafter. Contact area (in % out of a possible 100 %) decreased proximally between the 1- and 3-year follow-up.
  
  
  CONCLUSIONS
  Proximal cortical and cancellous bone density loss and decrease of contact area indicate that metaphyseal fixation cannot be achieved. The lack of cortical BD loss and increase of contact area values below the trochanter minor suggest diaphyseal fixation.
authors.affiliation: Department of Orthopaedic Surgery, Friedrich-Alexander-University of Erlangen-Nuremberg, Rathsberger Str. 57, 91054, Erlangen, Germany.
authors.forename: Alexander M
authors.initials: AM
authors.lastname: Kress
authors.forename: Rainer
authors.initials: R
authors.lastname: Schmidt
authors.forename: Tobias E
authors.initials: TE
authors.lastname: Nowak
authors.forename: Melanie
authors.initials: M
authors.lastname: Nowak
authors.forename: Lothar
authors.initials: L
authors.lastname: Haeberle
authors.forename: Raimund
authors.initials: R
authors.lastname: Forst
authors.forename: Lutz A
authors.initials: LA
authors.lastname: Mueller
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000379:methods*; D015519:Bone Density; D005260:Female; D005269:Femur / Q000033:anatomy & histology; D005272:Femur Neck; D005500:Follow-Up Studies; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011474:Prosthesis Design; D013314:Stress, Mechanical; D013997:Time Factors; D014057:Tomography, X-Ray Computed / Q000379:methods