Femoral Neck Notching in Dual Mobility Implants: Is This a Reason for Concern?

BackgroundDual mobility (DM) total hip arthroplasty (THA) implants have been advocated for patients at risk impingement due to abnormal spinopelvic mobility. Impingement against cobalt-chromium acetabular bearings, however, can result in notching of titanium femoral stems. This study investigated the incidence stem associated with DM and sought identify factors.MethodsA multicenter retrospective reviewed 256 modular 32 monoblock components minimum 1-year clinical radiographic follow-up, including 112 revisions, 4 conversion THAs, 172 primary THAs. Radiographs were inspected evidence calculate inclination anteversion. Revisions dislocations recorded.ResultsTen cases discovered (3.5%), all cylindrospheric (P = .049). Notches first observed radiographically mean 1.3 years after surgery (range 0.5-2.7 years). Notch location was anterior (20%), superior (60%), or posterior (20%) on prosthetic neck. depth ranged from 1.7% 20% neck diameter. Eight had lumbar pathology that affect None these notches resulted fracture, 2.7-year follow-up 1-7.6 There no revisions notching.ConclusionFemoral identified 3.5% cases, slightly surpassing dislocation rate a cohort selected instability. Although not catastrophic failures thus far, further sequelae is warranted. Component position, mobility, implant design may influence risk.