With new technologies and materials emerging, are cementless femoral stems becoming the clinical mainstream, making cemented femoral stems truly "outdated"?
Origin of Hip Joint Prosthesis
In 1958, Professor John Charnley used acrylic bone cement to fix an artificial hip joint, marking the world's first low-wear hip joint prosthesis. It evenly distributes force to the bone, with a fixation strength 200 times higher than previous screw-based methods. This became the "gold standard" of hip replacement, ushering in the era of cemented femoral hip prostheses.
Cemented Femoral Hip Prosthesis
"Two Philosophies" Corresponding to "Two Designs"
These two philosophies naturally lead to two corresponding designs.
· Mainstream Design ·
① Presence of Collar: Theoretically, a collar can reduce the circumferential stress on the cement mantle to prevent sinking. However, due to the emergence of the "limited subsidence theory" and the fact that the cement is prone to fracture under the collar, leading to failure, the collarless has become the mainstream choice.
② Shape Selection: "Straight stem" is more likely to form a complete cement mantle; "curved stem" is generally avoided.
③ Optimal Stem Length: 120-145mm. Mathematical models show that short stems increase proximal stress, while excessively long stems increase pressure and might obscure proximal focus, leading to cement mantle fracture.
(1) The stem's perimeter should be smooth, avoiding sharp edges to prevent cement fracture due to stress concentration.
(2) A trapezoidal cross-section is the optimal design, with wider outer and narrower inner sides. This cross-section maximizes the ratio of maximum compressive stress on the inner side of the femoral stem to maximum tensile stress on the outer side. This reduces tensile stress on the cement, making it the safest choice.
⑤ Surface Treatment: Ultra-mirror polished surface ensures stem smoothness, facilitating "finite subsidence."
JUST TAICH Product Advantages
· Ideal choice for revising cemented stems
· Excellent resistance to rotation
· Highly polished surface for a better hinge mechanism
· Dual-standard implantation line for optimal medullary placement
· Specialized stem models available
The JUST Medical TAICH cemented femoral stem series not only inherits the advantages of mainstream designs mentioned above but also offers advantages in total hip arthroplasty surgeries for elderly patients and those with severe osteoporosis. This provides clinical doctors with more options for treating various medical conditions.