The clearly visible lysis seam on the x-ray image between the proximal stem area and the corresponding cement coat allows oscillation of the proximal stem, which may lead to a fatigue fracture.We assume that the bony support was insufficient around the prosthesis, due to resorption processes.Probably a too wide offset resulted from an not optimal choice of the xl-neck.The visual inspection shows an intensely polished medial and dorsal surface of the proximal fractional part.This evidence confirms the assumption of the oscillated proximal stem.Further laboratory investigations show that the fatigue break (approx.80%) started at the highest bending stress side - the lateral side.In this area the typically swing stripes could be detected.The remaining 20% are caused by force fracture.No stem-surface damage is visible nearby the fracture starting point but the appearance of microporosity.Unfortunately the present micro-porosity cannot be detected by the current standard x-ray evaluation that we use.The insufficient bony support contributed to the early prosthesis failure.Furthermore the obesity of the patient, which is a relative contraindication as listed in our surgical technique, facilitated the adverse event.This event occurred outside of the u.S.And involves a product that was manufactured outside of the u.S.However because the affected product is also marketed in the u.S., (b)(4) is submitting this mdr to ensure full compliance with 21 cfr part 803.(b)(4).
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