Biomechanical comparison of newly designed stemless prosthesis and conventional hip prosthesis--an experimental study.
Local bone loss after implantation of traditional stem-type prostheses remains an unsolved problem during the long-term application of total hip replacement. The stress shielding effect and osteolysis were thought to be the two main factors that result in local bone loss after prosthesis implantation. A newly designed stemless cervico-trochanteric (C-T) prosthesis was thus developed to reduce stress shielding and osteolysis caused by the implantation of conventional stem-type prosthesis. Eight synthetic femora were implanted with C-T and porous coated anatomic (PCA) prostheses. Under 2,000-Newton load, the surface strains of proximal femora were compared between the intact, PCA press-fit femora and the C-T implanted femora with three different fixation modes: two-screw fixation, three-screw fixation, and three-screw combined with cement fixation. The results revealed that stress shielding in the C-T implanted femora was significantly eliminated compared to that of the PCA implanted femora (p<0.01). No statistical difference in strain magnitude was found for the C-T implanted femora among the three different fixation modes (p>0.1). The C-T implanted femur has more physiological strain distribution. Moreover, from the C-T prosthetic characteristic design, the localized osteolysis would be also reduced due to the overall coverage of neck-trochanteric area. The newly designed C-T prosthesis may be a useful alternative to the traditional stem-type prosthesis in the future.
Tai
Ching-Lung
CL
Department of Biomedical Engineering, Chung-Yuan Christian University, Chungli, Taiwan.
Lee
Mel S
MS
Chen
Weng-Pin
WP
Hsieh
Pang-Hsin
PH
Lee
Po-Chen
PC
Shih
Chun-Hsiung
CH
D001178:Arthroplasty; D019644:Arthroplasty, Replacement, Hip / Q000379:methods*; D001696:Biomechanical Phenomena; D001698:Biomedical Engineering / Q000379:methods*; D005269:Femur / Q000473:pathology; D006622:Hip Prosthesis; D006801:Humans; D008953:Models, Anatomic; D016348:Osseointegration; D010014:Osteolysis; D019736:Prostheses and Implants; D011474:Prosthesis Design / Q000379:methods; D019919:Prosthesis Implantation; D013314:Stress, Mechanical