Research has evaluated both traditional and new fully hydroxyapatite-coated hip replacement stems. Findings suggest that the new stems provide larger contact areas, whereas traditional stems better maintain bone density over time. This research aims to enhance patient outcomes and lower the chance of revision surgeries.
While requiring a hip replacement is unfortunate, having to go through the procedure multiple times is even more regrettable.
Researchers from Osaka Metropolitan University have shed light on the effectiveness of two different stem types used in total hip replacement procedures. Their discoveries are intended to improve long-lasting success, enhance patients’ quality of life, and decrease the need for repeat surgeries.
Their findings were published in The Bone & Joint Journal on June 1.
The hip joint connects the thighbone (femur) to the pelvis, playing an essential role in supporting weight and enabling movement. Total hip replacement, also known as total hip arthroplasty, involves substituting a damaged hip joint with an implant to relieve pain and discomfort caused by degeneration or aging.
“Post-surgery, a reduction in bone density around the femur can heighten the risk of fractures and the loosening of the artificial joint, which may lead to a hip revision surgery,” stated Yohei Ohyama, the lead author, surgeon, and PhD candidate at the Osaka Metropolitan University Graduate School of Medicine.
The team therefore undertook a thorough examination of changes in bone density and contact between the stem and femur for two types of stems used in total hip replacement: traditional fully hydroxyapatite (HA)-coated stems and the newer fully HA-coated variants. Hydroxyapatite is a naturally occurring mineral form of calcium apatite and is a principal element of bone. The established HA stems are famed for their excellent long-term performance, while the newer HA stems—shorter in length—are tailored for minimally invasive operations.
The study comprised 66 patients, with 36 receiving traditional HA stems and 30 receiving the newer HA stems. Bone density around the implants was evaluated using dual-energy x-ray absorptiometry one and two years following the surgery. A 3D density mapping technique was utilized to assess stem contact with the femoral cortical bone.
The results revealed significantly larger contact areas in specific regions of the femur with the new HA stems. In contrast, the traditional HA stems exhibited improved bone density around the upper inner femur (proximal-medial femur) at the two-year follow-up, while the new HA stems displayed a decline.
This study underscores the different fixation characteristics and the bone density retention capabilities of both stem types. Although the new HA stems provide larger adequate contact surfaces, the traditional HA stems showed better long-term maintenance of bone density.
These results are vital for surgeons in choosing the appropriate stems for total hip replacements, as they strive to maximize patient outcomes and extend implant durability.
“Total hip arthroplasty is a transformative procedure that enhances the healthy lifespan of patients and elevates their quality of life,” said Ohyama. “We aspire that our findings will help shape treatment approaches that allow artificial joints to serve as lifelong solutions.”
