PMC9553682_01
Anteroposterior and axial radiographs of the left hip from case one at the time of the dislocated stress fracture of the femoral neck (a) on the second postoperative day after hybrid THA (b) and at the one-year mark (c) Several months after untreated acute PJI with S. aureus the implants are well fixed, in particular, the cup is fully integrated. Note thinning out of the cancellous bone in the proximal femur as well as of the cortical bone on the femoral diaphysis, with an enlarged medullary cavity, indicating osteoporosis. The patient suffered from refractory anorexia nervosa.
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fig1
Conventional radiographs showed well-fixed components without signs of loosening (Figure 1).
PMC9553682_02
Anteroposterior and axial radiographs of the right hip of Case Two, 6 years after revision THA (a) Despite a newly diagnosed S. lugdunensis PJI, components show no signs of loosening. At the 10 years mark (b) after 4 years of documented, untreated PJI, the radiolucent line observable frequently in Gruen zone 1 with this type of stem (black arrows) remains stable. There is also some evidence of diaphyseal, endocortical osteolysis (white arrows), but no subsidence of the stem, and endosteal ossification at the tip of the stem remains stable. The cup is well fixed. In an asymptomatic patient, this implant can be considered sufficiently integrated. Note the poor contrast, particularly on the axial views in the lower row, due to morbid obesity (BMI of 48 kg/m2).
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fig2
The uncemented stem shows a radiolucent line around its shoulder but has not subsided in 10 years and has no pedestal sign (Figure 2).