MRI with state-of-the-art metal artifact reduction after total hip arthroplasty: periprosthetic findings in asymptomatic and symptomatic patients

OBJECTIVES: To assess the spectrum of periprosthetic MRI findings after primary total hip arthroplasty (THA). METHODS: This multi-center cohort study analyzed 31 asymptomatic patients (65.7 ± 12.7 years) and 27 symptomatic patients (62.3 ± 11.9 years) between 6 months and 2 years after THA. 1.5-T MRI was performed using Compressed Sensing SEMAC and high-bandwidth sequences. Femoral stem and acetabular cup were assessed for bone marrow edema, osteolysis, and periosteal reaction in Gruen zones and DeLee and Charnley zones. Student t test and Fisher's exact test were performed. RESULTS: The asymptomatic and symptomatic groups showed different patterns of imaging findings. Bone marrow edema was seen in 19/31 (61.3%) asymptomatic and 22/27 (81.5%) symptomatic patients, most commonly in Gruen zones 1, 7, and 8 (p ≥ 0.18). Osteolysis occurred in 14/31 (45.2%) asymptomatic and 14/27 (51.9%) symptomatic patients and was significantly more common in Gruen zone 7 in the symptomatic group (8/27 (29.6%)) compared to the asymptomatic group (2/31 (6.5%)) (p = 0.03). Periosteal reaction was present in 4/31 asymptomatic (12.9%) and 9/27 symptomatic patients (33.3%) and more common in Gruen zones 5 and 6 in the symptomatic group (p = 0.04 and 0.02, respectively). In the acetabulum, bone marrow edema pattern was encountered in 3/27 (11.1%) symptomatic patients but not in asymptomatic patients (p ≥ 0.21). Patient management was altered in 8/27 (29.6%) patients based on MRI findings. CONCLUSIONS: Periprosthetic bone marrow edema is common after THA both in asymptomatic and symptomatic patients. Osteolysis and periosteal reaction are more frequent in symptomatic patients. MRI findings led to altered patient management in 29.6% of patients. KEY POINTS: • Bone marrow edema pattern was frequent in both asymptomatic and symptomatic patients after THA, particularly around the proximal femoral stem in Gruen zones 1, 7, and 8. • Osteolysis was significantly more frequent in symptomatic patients in Gruen zone 7. • Periosteal reaction occurred more frequently in symptomatic patients in Gruen zones 5 and 6