Comparison of fit and fill between anatomic stem and straight tapered stem using virtual implantation on the ORTHODOC workstation.

The objective of this article was to determine the influence of stem design on fit and fill using the preoperative planning workstation of the ROBODOC system. Anatomic ABG and straight Osteolock femoral components were virtually implanted into 50 femora (25 from patients with developmental dysplasia of the hip (DDH), 25 morphologically normal) on the workstation display. Fit and fill, and length of the proximal posterolateral femoral cortex removed by milling (LPFCR), were measured on the cross-sectional images. Lateral curvature (alpha angle) and anteversion of the femur were evaluated. The ABG components showed significantly better fit than the Osteolock components at the levels proximal to the lesser trochanter. The Osteolock components showed significantly greater LPFCR than the ABG components, especially in the patients with DDH. The patients with DDH showed significantly greater alpha angle and femoral anteversion than those with morphologically normal femora. With the Osteolock components, the alpha angle correlated significantly with femoral anteversion and LPFCR. Use of an anatomic proximal body of the stem helped to improve the proximal canal fit. Greater LPFCR was required when a straight stem was implanted in patients with a relatively high alpha angle.

[1]  W. Bargar,et al.  Primary and Revision Total Hip Replacement Using the Robodoc® System , 1998, Clinical orthopaedics and related research.

[2]  P. Noble,et al.  A comparison of alternative methods of measuring femoral anteversion. , 1998, Journal of computer assisted tomography.

[3]  S. Naidu,et al.  Initial stability of a modular uncemented, porous-coated femoral stem: a mechanical study. , 1996, American journal of orthopedics.

[4]  A Coblentz,et al.  Micromotion, Fit, and Fill of Custom Made Femoral Stems Designed With an Automated Process , 1996, Clinical orthopaedics and related research.

[5]  R. Jinnah,et al.  Computerized templating in uncemented total hip arthroplasty to assess component fit and fill. , 1992, The Journal of arthroplasty.

[6]  C. Engh,et al.  The case for porous-coated hip implants. The femoral side. , 1990, Clinical orthopaedics and related research.

[7]  H. Tullos,et al.  The anatomic basis of femoral component design. , 1988, Clinical orthopaedics and related research.

[8]  Nobuhiko Sugano,et al.  Stem length and canal filling in uncemented custom-made total hip arthroplasty , 1999, International Orthopaedics.

[9]  N Sugano,et al.  The morphology of the femur in developmental dysplasia of the hip. , 1998, The Journal of bone and joint surgery. British volume.

[10]  T Nishii,et al.  Computed-tomography-based computer preoperative planning for total hip arthroplasty. , 1998, Computer aided surgery : official journal of the International Society for Computer Aided Surgery.

[11]  R. Bourne,et al.  Ingrowth surfaces. Plasma spray coating to titanium alloy hip replacements. , 1994, Clinical orthopaedics and related research.

[12]  R. Huiskes,et al.  Primary fit of the Lord cementless total hip. A geometric study in cadavers. , 1988, Acta orthopaedica Scandinavica.

[13]  C. Engh,et al.  THE FACTORS GOVERNING BONE INGROWTH, STRESS SHIELDING, AND CLINICAL RESULTS , 1987 .

[14]  C. Ranawat,et al.  Total hip replacement in congenital dislocation and dysplasia of the hip. , 1979, The Journal of bone and joint surgery. American volume.