Comparison of radiographs, tomosynthesis and CT with metal artifact reduction for the detection of hip prosthetic loosening

To evaluate the diagnostic performance of digital tomosynthesis (DTS) for the diagnosis of hip prosthesis loosening (PL) compared with conventional radiographs and CT with metal artifact reduction (CT-MAR). Forty-nine patients with painful hip prosthesis were prospectively included and underwent anteroposterior and lateral radiographs, anteroposterior DTS and CT-MAR of the hip. This study was approved by the local ethics committee, and all patients signed an informed consent form. Images were evaluated independently by two radiologists. Periprosthetic radiolucent lines wider than 2 mm found in two or more Gruen or De Lee and Charnley zones were considered diagnostic of PL. All cases of PL were confirmed surgically. Patients with a stable radiological follow-up for at least 1 year with an alternative cause for the symptoms or with no surgical evidence of PL were considered PL negative. There were 21 cases of PL, 9 unilateral and 12 bilateral. For both the acetabular and femoral sides, DTS had a specificity for PL detection similar to that of conventional radiographs and CT-MAR (98.5–100%, 96.9%–100% and 96.9–95.4% respectively for both readers) and a sensitivity similar to conventional radiographs (39.9–45.4% versus 33.3–51.5% for both readers) but lower than CT-MAR (84.85% for both readers). The interobserver agreement was 0.84 for CT-MAR, 0.53 for DTS and 0.39 for conventional radiographs. DTS has a similar diagnostic performance to radiographs for the diagnosis of PL with a better interobserver agreement. The sensitivity however remains lower than that of CT-MAR. • Plain radiograph is still the first imaging step when hip prosthesis loosening is suspected. • Interobserver agreement is better with digital tomosynthesis than radiographs. • Sensitivity of CT with state-of-the-art metal artifact reduction is superior to that of digital tomosynthesis.