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Porous-coated total hip replacement
C A Engh1, J P Hooten, K F Zettl-Schaffer
1Anderson Orthopaedic Research Institute, Arlington, VA 22206.
Insights
Porous-coated hip prostheses show excellent durability over 15 years, with low revision rates for femoral stems (1.5%) and acetabular cups (2.2%). These implants offer reliable fixation and long-term performance in total hip arthroplasty.
Area of Science:
- Orthopedic Surgery
- Biomaterials Science
- Medical Device Engineering
Background:
- Fifteen years of clinical data on porous-coated hip prostheses were analyzed.
- Durability of porous-coated fixation was assessed through a clinical follow-up study.
- Comparison with cemented acetabular components was included.
Purpose of the Study:
- To evaluate the long-term clinical performance and revision rates of porous-coated femoral and acetabular components in total hip arthroplasty.
- To assess the mechanical stability and bone remodeling associated with porous-coated implants.
- To compare the outcomes of porous-coated components with traditional cemented acetabular components.
Main Methods:
- Clinical follow-up of 393 cases treated before 1985, documenting revisions for femoral and acetabular components.
- Analysis of postmortem specimens (15 patients) including mechanical testing of femoral components.
- Dual-energy X-ray absorptiometry (DEXA) to assess periprosthetic bone mineral content in paired femora.
Main Results:
- Low revision rates for porous-coated femoral stems (1.5%) and acetabular cups (2.2%).
- Cemented acetabular components had a higher revision rate (7.5%).
- Mechanical testing showed minimal micromotion (<40 microns) at the porous surface.
- DEXA revealed 5%-52% periprosthetic bone mineral loss due to remodeling.
Conclusions:
- Porous-coated hip prostheses demonstrate durable fixation and low revision rates over 15 years.
- Porous-coated implants offer a reliable alternative to cemented components, particularly for acetabular fixation.
- Bone remodeling can lead to significant periprosthetic bone mineral loss, warranting further investigation.
Abstract:
Fifteen years of clinical experience with porous-coated prostheses demonstrated the durability of this type of fixation. This experience was documented by clinical follow-up study of the 393 cases treated by the senior author before 1985. Only six of these femoral components have been revised: three for loosening, two for stem breakage, and one for infection. Thus, the revision rate for the porous-coated stems was 1.5%. Porous-coated acetabular components were used in 227 of the arthroplasties. Five of these porous-coated cups have been revised: four for malposition leading to dislocation and one for late loosening secondary to osteolysis. Thus, the revision rate for these porous-coated acetabular components was 2.2%. Twenty bipolar and 146 cemented acetabular components were used in the remaining 166 cases treated before 1985. Eleven (7.5%) of the cemented acetabular components were revised. Revisions of the porous-coated components were rare in the first ten postoperative years. The clinical data were supplemented with analysis of postmortem specimens from 15 patients. Mechanical testing of the femoral specimens showed the relative micromotion at the porous surface to be exceptionally small (less than 40 microns). Seven of these postmortem retrievals involved cases with unilateral arthroplasties. In these cases, the contralateral normal femur also was removed, and a prosthesis identical to that in the in vivo implanted side was inserted to simulate the immediate postoperative condition. Dual-energy X-ray absorptiometry (DEXA) of the seven paired femora demonstrated that bone remodeling can be expected to produce a 5%-52% loss of periprosthetic bone mineral content, with the greatest loss occurring in the more osteoporotic patients.(ABSTRACT TRUNCATED AT 250 WORDS)