Cement thickness of at least 2 mm is generally associated with more favorable results for the femoral component in cemented hip arthroplasty. However, French-designed stems have shown favorable outcomes even with thin cement mantle. The biomechanical behaviors of a French stem, Charnley-Marcel-Kerboull (CMK) and cement were researched in this study. Six polished CMK stems were implanted into a composite femur, and one million times dynamic loading tests were performed. Stem subsidence and the compressive force at the bone-cement interface were measured. Tantalum ball (ball) migration in the cement was analyzed by micro CTObjective
Methods
Favourable results for collarless polished tapered stems have been reported, and cement creep due to taper slip may be a contributing factor. However, the ideal cement thickness around polished stems remains unknown. We investigated the influence of cement thickness on stem subsidence and cement creep. We cemented six collarless polished tapered (CPT) stems (two stems each of small, medium and large sizes) into composite femurs that had been reamed with a large CPT rasp to achieve various thicknesses of the cement mantle. Two or three tantalum balls were implanted in the proximal cement in each femur. A cyclic loading test was then performed for each stem. The migration of the balls was measured three-dimensionally, using a micro-computed tomography (CT) scanner, before and after loading. A digital displacement gauge was positioned at the stem shoulder, and stem subsidence was measured continuously by the gauge. Final stem subsidence was measured at the balls at the end of each stem.Objectives
Methods
Correction and arthrodesis for cervical kyphosis associated with atetoid cerebral palsy has been considered to be difficult because of their involuntary neck movements and severe deformity. The aim of this study is to evaluate the surgical outcome of midline T-saw laminoplasty and posterior arthrodesis using pedicle screws. 15 patients were retrospectively reviewed. There were 6 women and 9 men, with a mean age 52.9 years (range 31–71 years). Mean follow-up period was 43 months (range 24–84 months). For clinical evaluation, the Japanese Orthopaedic Association (JOA) score and Barthel index (BI) which shows independence in ADL were used. For radiographic evaluation, change of C2–C7 Cobb angle of sagittal alignment, adjacent segment instability after the surgery were evaluated.Introduction
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