Osteolysis is an important cause of artificial joint revision. However, Justinas Stucinskas et al, Department of Orthopaedics, Kantonsspital Hospital, Switzerland, concluded that femoral bone defects after total artificial hip arthroplasty (THA) are not uncommon, but the cause is not exclusively osteolysis. Stress masking and osteoporosis can have similar imaging manifestations to osteolysis, but do not require revision of the joint. Therefore, Justinas et al. performed a correlative observational study to determine the changes in femoral bone quality in patients after THA under normal circumstances. Justinas et al. used the same prosthesis (cemented Müller straight stem prosthesis) procedure as a guideline and selected 35 cases from 161 consecutive cases (165 hips) who underwent THA for osteoarthritis without loosening or revision between 1984 and 1987 for analysis of bone cortical thickness changes, and then selected 10 unilateral THA cases from these cases for imaging analysis. Justinas et al. measured in 6 planes of the femur (Figure 3) and found that there was no significant difference in the femoral cortex bilaterally in the short time after THA in patients, whereas a long follow-up revealed bone loss bilaterally, with more pronounced thinning of the bone cortex on the operated side and more severe proximally than distally (see Table 1 for details). Among the possible causes of bone remodeling, age at the time of surgery was the only significant influence, while gender, prosthesis size, material of the artificial femoral head, unilateral or bilateral THA, and Harris hip score were not significantly related to bone cortical thinning. Justinas et al. suggested that the main cause of bone cortical thinning in patients may be stress masking, a phenomenon found in other types of cemented prostheses. Histological studies have found bone atrophy over the entire surface of the bone after contact between the prosthesis and the bone, and the bone atrophy was more pronounced in the middle part of the prosthesis. Justinas et al. used a “form-fitted” Müller prosthesis, which has a more pronounced stress effect due to the close contact between the prosthesis and the bone without a cemented liner. There is a close relationship. In explaining other factors that may influence femoral atrophy, Justinas et al. concluded that their study showed that only age and bone atrophy were significantly correlated, while other factors were not significant. Furthermore, the femoral cortex on the side of the patient without THA thinned uniformly with age, and comparing the changes on the operative side suggests that age is not a direct cause of prosthesis loosening, but rather that patients of advanced age are more sensitive to stress effects.