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Difference in Postoperative Periprosthetic Bone Mineral Density Changes Between 3 Major Designs of Uncemented Stems:
Yutaka Inaba1, Naomi Kobayashi1, Masatoshi Oba1
1Department of Orthopaedic Surgery, Yokohama City University, Yokohama, Japan.
Insights
Different uncemented femoral stem designs impact bone mineral density (BMD) loss after total hip arthroplasty (THA). The tapered wedge stem maintained medial BMD, while the Zweymüller stem preserved lateral BMD over three years.
Area of Science:
- Orthopedic surgery
- Biomaterials science
- Bone physiology
Background:
- Periprosthetic bone loss due to stress shielding is a concern in uncemented total hip arthroplasty (THA), particularly for younger patients.
- Femoral stem design can influence the extent of postoperative stress shielding and subsequent bone loss.
- Understanding stress shielding characteristics of different femoral stems is crucial for optimizing THA outcomes.
Purpose of the Study:
- To compare bone mineral density (BMD) changes in the femur following primary THA among three major types of uncemented femoral stems.
- To evaluate the impact of femoral stem design on stress shielding and associated bone loss.
- To provide insights into the long-term effects of different stem designs on periprosthetic bone health.
Main Methods:
- A comparative study involving 89 hips undergoing primary THA with three distinct uncemented stem designs: fit-and-fill (VerSys), tapered rectangular Zweymüller (SL-Plus), and tapered wedge (Accolade TMZF).
- Bone mineral density (BMD) measurements were conducted using a HOLOGIC Discovery device.
- Follow-up assessments included BMD analysis and Harris Hip Score at 1, 2, and 3 years post-surgery.
Main Results:
- The tapered wedge-type stem group maintained medial-proximal femur BMD for three years post-THA.
- The Zweymüller-type stem group maintained lateral-proximal femur BMD for three years post-THA.
- No significant differences in Harris Hip Score were observed among the three stem groups preoperatively and up to three years post-surgery.
Conclusions:
- Significant variations exist in postoperative proximal femur BMD loss among the three commonly used uncemented femoral stem types.
- Femoral stem design plays a critical role in modulating stress shielding and preserving periprosthetic bone density.
- These findings highlight the importance of stem selection in managing bone loss after uncemented THA.
Background:
Although few studies have examined the direct effect of stress shielding on clinical outcomes, periprosthetic bone loss due to stress shielding is still an issue of concern, especially when physicians perform uncemented total hip arthroplasty (THA) in younger patients. Differences in femoral stem design may affect the degree of postoperative stress shielding. Therefore, the characteristics of the behavior for stress shielding of each type of femoral stem should be determined. This study compares differences in bone mineral density (BMD) change in the femur after primary THA between 3 major types of uncemented stems.
Methods:
Among a total of 89 hips, 26 hips received THA with a fit-and-fill type stem (VerSys Fiber Metal MidCoat; Zimmer, Inc, Warsaw, IN), 32 hips received a tapered rectangular Zweymüller-type stem (SL-Plus; Smith & Nephew Inc, Memphis, TN), and 31 received a tapered wedge-type stem (Accolade TMZF; Stryker Orthopaedics, Mahwah, NJ). BMD measurements were performed with a HOLOGIC Discovery device (Hologic Inc, Waltham, MA).
Results:
BMD in the medial-proximal femur was maintained for 3 years after THA in the group with the tapered wedge-type stem. BMD in the lateral-proximal femur was maintained for 3 years after THA in the group with the Zweymüller-type stem. There were no significant differences in the Harris Hip Score among the 3 stem groups preoperatively and 1, 2, and 3 years after surgery.
Conclusion:
There are clear differences in postoperative BMD loss of the proximal femur among these 3 commonly used uncemented stems.
