title: Cementless Tapered Wedge Femoral Stems Decrease Subsidence in Obese Patients Compared to Traditional Fit-and-Fill Stems.
abstract: Femoral component stability and resistance to subsidence is critical for osseointegration and clinical success in cementless total hip arthroplasty. The purpose of this study was to radiographically evaluate the anatomic fit and subsidence of 2 different proximally tapered, porous-coated modern cementless femoral component designs.
  
  
  
  A retrospective cohort study of 126 consecutive cementless total hip arthroplasties was performed. Traditional fit-and-fill stems were implanted in the first 61 hips with the remaining 65 receiving morphometric tapered wedge stems. Preoperative bone morphology was radiographically assessed by the canal flare index. Canal fill in the coronal plane, subsidence, and the sagittal alignment of stems was measured digitally on immediate and 1-month postoperative radiographs.
  
  
  
  Demographics and canal flare indices were similar between groups. The percentage of femoral canal fill was greater in the tapered wedge compared to the fit-and-fill stem (P = .001). There was significantly less subsidence in the tapered wedge design (0.3 mm) compared to the fit-and-fill design (1.1 mm) (P = .001). Subsidence significantly increased as body mass index (BMI) increased in the fit-and-fill stems, a finding not observed in the tapered wedge design (P = .013).
  
  
  
  An anatomically designed morphometric tapered wedge femoral stem demonstrated greater axial stability and decreased subsidence with increasing BMI than a traditional fit-and-fill stem. The resistance to subsidence, irrespective of BMI, is likely due to the inherent axial stability of a tapered wedge design and may be the optimal stem design for obese patients.
authors: Department of Orthopaedic Surgery, Indiana University School of Medicine, Indianapolis, Indiana.
authors: Tanner W
authors: TW
authors: Grant
authors: IU Health Saxony Hospital, Orthopedics, Indiana University Health Physicians Orthopedics and Sports Medicine, Fishers, Indiana.
authors: Luke R
authors: LR
authors: Lovro
authors: IU Health Bloomington Hospital, Orthopedics, Indiana University Health Southern Indiana Physicians, Bloomington, Indiana.
authors: David J
authors: DJ
authors: Licini
authors: IU Health Saxony Hospital, Orthopedics, Indiana University Health Physicians Orthopedics and Sports Medicine, Fishers, Indiana.
authors: Lucian C
authors: LC
authors: Warth
authors: IU Health Saxony Hospital, Orthopedics, Indiana University Health Physicians Orthopedics and Sports Medicine, Fishers, Indiana.
authors: Mary
authors: M
authors: Ziemba-Davis
authors: Department of Orthopaedic Surgery, Indiana University School of Medicine, Indianapolis, Indiana; IU Health Saxony Hospital, Orthopedics, Indiana University Health Physicians Orthopedics and Sports Medicine, Fishers, Indiana.
authors: Robert M
authors: RM
authors: Meneghini
mesh_terms: D019644:Arthroplasty, Replacement, Hip / Q000295:instrumentation*; D005260:Female; D005269:Femur / Q000601:surgery; D006622:Hip Prosthesis / Q000706:statistics & numerical data*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000150:complications* / Q000601:surgery; D016348:Osseointegration; D011184:Postoperative Period; D011474:Prosthesis Design; D011859:Radiography; D012189:Retrospective Studies
keywords: BMI; canal fill; fit-and-fill stems; subsidence; tapered wedge stems; total hip arthroplasty