Turkey: Researchers Innovate Further in Creating Titanium Hip Implants

In ‘Design, manufacture, and fatigue analysis of lightweight hip implants,’ Turkish researchers Yunus E. Delikanli and Mehmet C. Kayacan explore and test better ways to fabricate hip implants for total hip arthroplasty (THA). Most humans are aware of the critical importance of their hip joints—especially when something goes wrong and a major health issue arises, or deterioration from age becomes an apparent, and painful.

The ball-and-socket joint allows humans to perform most of the required actions for mobility—from taking a seat, to walking or running—or more athletic activities requiring jumping. This joint is expected to handle a lot of wear and tear over a lifetime, and fractures due to trauma can occur at any age but are much more expected in the elderly. According to the research team, ‘heritage, nutrition, and lifestyle’ can play a role too.

“In cases involving high body weight and physical activity, the load on the femur increases, which in turn results in bending and torsional stresses in the femoral component of an implant,” stated the researchers. “If these stresses are repetitive and variable, fatigue fractures or deformations may arise in hip implants.

(a) Small pore (0.3 mm, KG) and (b) large pore (0.6 mm, BG) implants.

Striving to innovate further in creating implants, the researchers used titanium metal powder (Ti6Al4V alloy) for 3D printing. Nine samples were created, from .03 mm to solid, using Kubisch Raumzentrierten (KRZ) geometries in a lattice structure, with a porosity of 78.3 percent, 3D printed on an EOS M280 direct metal laser sintering (DMLS) machine. Upon fabrication of the samples, the researchers realized a reduction in weight of up to 17 percent—due to the ability to not only make complex structures but also with hollowed out interiors.

In testing, the research team found that ‘maximum equivalent stresses’ were exhibited in what is called the ‘neck region’ of each implant. Lightened implants exhibited greater stresses even with the same loading—attributed to less of a cross-sectional area, and a more complex one. Each implant was deemed successful after five million load cycles—with an infinite fatigue life.

Lightening process of the implants.

“All the implants produced with DMLS have been shown to exhibit enough fatigue performance according to the requirements of the ISO 7206 standard. In addition, FEA findings are highly consistent with fatigue test results,” concluded the researchers. “Thus, the displacements outside of the investigated pore size range can be predicted with sufficient accuracy by FEA. This enables us to save production costs and obtain an idea about the implant performance without carrying out any building process.”

Upon its inception decades ago, very few could have realized the impacts 3D printing and surrounding technologies would have on medical patients today, who are now able to enjoy a better quality of life due to a range of different implants and devices brought forward by innovative researchers who have created everything from surgical guides for replacement surgeries to knee implants to spinal implants.

Find out more about hip arthroplasty and the role of 3D printing here. What do you think of this news? Let us know your thoughts! Join the discussion of this and other 3D printing topics at 3DPrintBoard.com.

Cell development channels of KG (a) and BG (b) hip implants.