Abstract
Objective
It is known that stress shielding frequently occurs after total hip arthroplasty (THA). However, the status of bone metabolism in stress shielding region is not still clear. 18F-fluoride positron emission tomography (PET) is a useful tool for the quantitative evaluation of bone metabolism, which uptake relates with the activity of bone formation by osteoblast. In this study, we evaluated the status of bone turnover in stress shielding region using 18F -fluoride PET.
Design
A total of 88 hip joints from 70 cases after THA were analyzed using X-ray and 18F-fluoride PET. We classified these hips into 2 groups, stress shielding or non-stress shielding group. Each femur was divided into 7 regions by Gruen's zone classification. We measured SUV of 18F-fluoride PET in these regions and compared SUV to evaluate the difference of bone metabolism between 2 groups.
Results
Stress shielding was confirmed in 75 joints, which was confirmed in particularly zone 1, 2, 7. The significant difference between the SUV in 2 groups was not confirmed. The SUV was significantly higher in the proximal area compared to the distal area. There was no differences of SUV between groups divided by post-operative period, nor implant type.
Conclusions
Our results indicate that osteoblastic activities are maintained after THA even in stress shielding region. This observation indirectly suggested that high bone turn over may contribute to the BMD loss in stress shielding region.
