Dependency of cement mantle thickness on femoral stem design and centralizer

Deficient cement mantles may he detrimental with regard to long-term outcom e of cemented femoral stems. We performed a cadaver Study oil 48 left femor a with 4 different stem designs (1 anatomic, 3 straight) to study the influ ence of stem design, centralizer, and femur type on cement mantle thickness . A radiographic and microradiograhic analysis was done. Overall, 88% of st ems were aligned within 1 degrees of neutral in the frontal plane. In Gruen Zones 1 through 7, we measured 24 thin cement mantles (<2 mm) in 19 specim ens with no correlation to stem design or zone. In the sagittal plane, typi cal areas of thin cement mantles were identified in Gruen zones 8 and 9 (n = 39) and 12 (n = 21). The anatomic stem design carried the lowest risk (54 %) of producing a thin cement mantle proximally ill Gruen zones 8 and 9. Th e risk for straight stem designs was >90%. Straight Steins Without centrali zer showed the highest risk of thin cement mantles ill Gruen zone 12 (93%). Centralizers were efficient to prevent thin cement mantles in zone 12 but had [to effect proximally. Lateral radiographs are essential to allow for a dequate radiographic assessment of the cement mantle and stem alignment. Th ere is a high risk of producing thin cement mantles in Gruen zones 8 and 9, in particular when straight stems are used. Posterior canal entry and low neck osteotomies are essential. Anatomic stems respect the anatomy, allow f or more even cement mantles, minimize the risk of thin cement mantles Witho ut the use of centralizers, and may be considered in the femur with marked proximal bow.