Aseptic Loosening of Smaller Corail Stems in Heavy, Active Males: A Report of Three Cases

Abstract

Recent concerns have been raised regarding a higher failure rate with smaller size Corail stems. This case series examines early aseptic loosening with smaller stems in three large male patients with Dorr A bone. Each stem was fluoroscopically aligned and sized until stable with axial and rotational stress. In each case, failure occurred within six months due to symptomatic metaphyseal debonding. Careful analysis suggests a correlation of failure to small size stems that are comparatively 1) undersized relative to the metaphysis, 2) undersized relative to patient body mass index, and 3) undersized relative to the amount of offset created.

Small design modifications can improve the primary stability of a fully coated tapered wedge hip stem

“…The one Corail stem with more than 8 mm of subsidence was a typical example of a failed implantation with metaphyseal-diaphyseal mismatch in a femur of Dorr type A of an undersized stem (red circles in Fig 9 ) [ 11 , 12 , 48 ]. In the clinical situation such a large subsidence would probably have required a revision surgery.…”

“…The improved canal-fill-ratio of the Emphasys stem could result in lower subsidence as well as a lower risk of loosening in the respective case. The risk of loosening for a potentially undersized stem should always be considered when implanting a stem smaller than the templated size [6,7,[10][11][12]. Despite the fact that eight out of twelve specimens received stems one or two sizes smaller than the templated size of those eight, only one Corail stem exhibited severe subsidence which potentially would clinically lead to revision.…”

“…The increased risk for smaller sizes might be caused by a mismatch between the metaphyseal-diaphyseal geometry of the stem design and the anatomy of the human femur [ 9 , 10 ]. The surgeon can get the impression of sufficient stem primary stability during implantation due to distal (diaphyseal) contact and fixation of the stem, even so no sufficient stability has been achieved in the proximal (metaphyseal) region [ 11 , 12 ]. Male patients are more susceptible to this problem, as they are more likely to have femurs of Dorr type A.…”

“…Male patients are more susceptible to this problem, as they are more likely to have femurs of Dorr type A. The narrow diaphysis and wide metaphysis increases the risk of mismatch ("champagne flute shape") [10][11][12].…”