Computer assisted radiographic analysis of the periprosthetic bone remodeling -over twenty-year results of the cementless stems-

2000 Fiscal Year Final Research Report Summary

• Project/Area Number: 11671459
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Orthopaedic surgery
• Research Institution: JIKEI UNIVERSITY
• Principal Investigator: TAKEUCHI Hidemi Jikei University, School of Medicine, Department of Orthopaedic Surgery, Research Assistant, 医学部, 助手 (10179616)
• Co-Investigator(Kenkyū-buntansha): OTANI Takuya Jikei University, School of Medicine, Department of Orthopaedic Surgery, Lecturer, 医学部, 講師 (10176919)
• Project Period (FY): 1999 – 2000
• Keywords: Computer Assisted Graphical Analysis / Cementless Acetabular Component / Cancellous Condensation / Spot welds(海綿骨緻密化) / porous構造 / ステムの固定性 / レーザーデジタイザ

Research Abstract

To clarify the certain radiographical signs that can predict the very long term results of the stem fixation, we studied the periprosthetic bone remodeling of cementless hip prosthesis using a computer assisted radiographical analysis system. A series of 132 total hip arthroplasties using the Jikei 1st generation cementless femoral components were performed between 1971 and 1978 but we could follow up only 28 cases with over twenty years of radiographic sequence. Radiographic findings of these 28 cases were studied using mainly antero-posterior projection of pelvis, and in addition we used a computer assisted contrast enhancing method in order to visualize the detail of the light and shade of the X ray pictures of periprosthetic bone remodelings.
The overall results of the radiographical evaluation of this old type femoral components were unsatisfactory, and 79% of this series showed progressive migration (1mm per year on average), while 21% of them maintained biological fixation without subsidence for more than twenty years. We also found cancellous condensations (spot welds) around these osseointegrated stems which were observed from a couple of years after surgery. As time has gone-by, deterioration of bone quarity such as cortical thinning and cannal widening are observed, but the spot welds invariably exist with no sign of subsidence. these delicate findings were preserved over twenty years.
This old-fashioned femoral component has no porous surface, but has fine crosshatching grooves (0.5mm in width 0.2mm in depth), and it seemed to have functioned as a porous structure. Given that this hypothesis is correct, the radiographical appearance of spot welds could predict the fate of the fixability of porous-coated femoral components during the future few decades. Although the periprosthetic remodeling of spot welds is explained in full detail by C.Engh et al. in 1990, our study may be one of the longest follow-ups of the spot welds in relation to the stem fixation.