| dc.description.abstract | Bone remodeling around short-stemmed hip prostheses
Degree project in medicine, Carl Hellman, 2017, Department of Orthopedics, Sahlgrenska
University Hospital, Mölndal, Sweden
BACKGROUND
Total hip arthroplasty generally provides excellent results. During the last decades, prostheses
with a shorter stem has emerged as an alternative to conventional prostheses. Short-stemmed
prostheses are believed to reduce stress shielding and consequently reduce the loss of bone
mineral density (BMD) in the proximal femur. Easier revision surgery and improved
functional level are also proposed as benefits.
AIM
The aim of this study was to evaluate the change of BMD around two designs of shortstemmed
hip prostheses with the use of two conventional prostheses as controls.
METHODS
The first study evaluated the CFP (Collum Femoris Preserving) stem and the second one the
Fitmore stem. DXA (Dual-energy X-ray absorptiometry) scans were performed after surgery
and at 3, 6, 12 and 24 months. The BMD was measured in regions of interests (ROIs)
according to Gruen zones 1-7. Differences in change in BMD compared to baseline was
calculated at 2 years as primary outcome.
RESULTS
At 2 years follow-up, BMD values for the CFP stem was inferior in all ROIs compared to the
control. The difference was statistically significant in region 1, 6 and 7. The Fitmore stem was
inferior in ROIs 1, 2 and 4 but superior in ROIs 3, 5, 6 and 7. The difference was statistically
significant in ROIs 1, 2 and 5.
CONCLUSION
The CFP stem was found to be inferior in all ROIs with large decrease in BMD in the
proximal regions, indicating larger degree of stress shielding compared to the control. The
Fitmore stem was observed with larger decrease in BMD in the lateral ROIs, but lesser
decrease in the medial ROIs. Moderate differences between the Fitmore stem and the control
indicates that the Fitmore stem is not an inferior alternative with respect to stress shielding
and especially in younger patients. | sv |
