Breakage of the Implant after Total Knee Replacement: Cases Report

After total knee replacement, the breakage of implant is unusual. We have been experienced the two cases, one is the porous tibial plate breakage that Miller/Galante total knee system(MG TKS) and the other is the metal-backed polyethylene patellar component breakage with low contact stress(LCS) pros-thesis. Revisions have been performed by using Nexgen and modular posterior stabilized P.F.C. total knee system. Considerations of these causes are habitual abrupt hyperflexion of the knee and weight bear-ing. So we need to careful observation of long term clinical, radiological and survival results of total knee prosthesis in regard of the breakage of implant.

CT of Normal Variations of the Minute Central Skull Base Foramina

PURPOSE: To evaluate the CT appearance of normal variations in the minute central skull base foramina in infants and children. MATERIALS AND METHODS: One hundred and fourteen children under the age of 17 years without skull base abnormality underwent CT scanning. A high spatial frequency algorithm was used, and contiguous axial scanning parallel to the orbitomeatal line was performed from the foramen magnum to the orbital roof, with a 1-mm slice thickness. The presence or absence of eight foramina, pseudoforamina, or ossification centers including anterior presphenoidal foramen, posterior presphenoidal foramen, rostro-orbital pseudoforamen, intralateromedial postsphenoidal pseudoforamen, intrapostsphenoidal pseudoforamen, spheno-occipital pseudo-foramen, canalis basilaris medianus and intrasynchondral ossified bodies was analysed according to age. The presence of foramina or pseudoforamina was indicated if a ring-shaped structure was seen on two or more CT scans at the location anatomically predicted, and intrasynchondral ossified bodies were indicated if linear or dot-like structures with high attenuation accompanied spheno-occipital synchondrosis. RESULTS: CT indicated that within a certain age range, various kinds of foramina, pseudoforamina, and ossification centers were frequent. The anterior presphenoidal foramen was most commonly seen in infants aged 1-12 months (16/17, 94 %); the posterior presphenoidal foramen in children less than 2 years old(27/37, 73 % ) ; the rostro-orbital pseudoforamen in children aged 2 -5 years (9/17, 53%); intrapostsphenoidal pseudoforamen in children 6 -12 years old(20/37, 54%) and spheno-occipital pseudoforamen and intrasynchondral ossified bodies in children aged 13 -16 years. The canalis basilaris medianus was identified in about 20 % of all subjects regardless of age. CONCLUSION: Development of the minute central skull base foramina varied greatly according to age. Knowledge of the CT appearances of such embryologic variants of the central skull base should not only help Provide an understanding of complex skull base anatomy but also identify abnormal skull base development.