Jacques Bejui

Morphometry of the talocrural joint

Based on two orthogonal radiologic views, the authors present a morphometric study of the talocrural joint. In 50 normal subjects, 10 parameters were measured and divided into 3 groups: the distal tibial joint surface parameters, the malleolar parameters and the talar parameters. These parameters were treated in both a descriptive and a correlative analysis. If the talocrural joint is a hinge joint whose talar articular surface can be simplified and classed as a cylinder segment, it is possible to calculate its curve radius. Then the correlative analysis allows to define the talar parameters and the corresponding parameters of the distal tibial joint surface. The malleolar parameters are independent factors. This study is the first morphologic analysis to serve as a basis for an ankle arthroplasty.

Acetabular anatomy and the relationship with pelvic vascular structures Implications in hip surgery

Most direct vascular trauma occurring during hip surgery results from injury to pelvic vascular structures which are not visible during the procedures of reaming, drilling holes or the fixation of screws. In this study, 5 pelves of fresh cadavers were injected with a radiopaque mixture and were visualised with a scanner according to 5 predetermined sections. Bone depth of the acetabulum was measured in each section. A calculation was made describing the minimal distance separating the inner cortex from the principal pelvic vessels. After an anatomic dissection of each pelvis, the relationship between the vessels and screws of the fixation cup, implanted identically on the quadranted acetabulum, was observed.The screws placed in the anterior and inferior quadrants and the center of the acetabulum endangered the external iliac v. and a. and the obturator pedicle. The depth of the periacetabular bone was greater in the superior and posterior quadrants. The inferior gluteal, pudendal and superior gluteal aa. were more than ten mm from the posterior wall. Conversely, the external iliac and obturator pedicles came in contact with the osseous surface on which they lay. A projection of the vessels on the acetabulum was made, and the reproducible character of the acetabular-quadrant system was verified. The superior quadrant offers all the characteristics of a vascular safe zone. A knowledge of these anatomic relationships explain vascular trauma in pelvic fractures and helps to prevent vascular injury in hip surgery.

Anatomical basis for the choice of the femoral implant in the total hip arthroplasty

There is within the population a considerable variation in the endosteal canal anatomy of the proximal extremity of the femur. This anatomical variation might jeopardize the result of the total hip arthroplasty when the surgeon uses a cementless femoral shaft. Inded, if the secondary fixation of an implant stays under the dependency of many parameters, one has to obtain before anything else a very good primary stability, obtained by the morphological appropriateness of the bone-implant. The authors propose to define the cementless indications, as regards total hip arthroplasty, defining two radio-anatomical parameters: the Cortico-Medullary Index and the Femoral Flare Index.

Arthroplastie totale de hanche avant 50 ans — Choisir l’implant fémoral: Avec ou sans ciment? standard ou “sur mesure”?

The shape of the femoral canal is variable, much more variable than most contemporary designs of femoral components would suggest or can accomodate. Several studies have demonstrated the clinical importance of a close match between the dimensions of the femur and the implanted prosthesis. The clinical significance ofbone implant proximal fit has been noted for cementless mode fixation. A practical consequence of the variability of the proximal endosteal canal is that different femoral components may be needed for all the patients of the population. For the autors, the choice of the technique (cement or cementless), and the choice of the optimal femoral stem (standard or custom-made implant) depends on two radiologic parameters: I.C.M. and I.E.F.; these parameters are defined and analysed.The shape of the femoral canal is variable, much more variable than most contemporary designs of femoral components would suggest or can accomodate. Several studies have demonstrated the clinical importance of a close match between the dimensions of the femur and the implanted prosthesis. The clinical significance ofbone implant proximal fit has been noted for cementless mode fixation. A practical consequence of the variability of the proximal endosteal canal is that different femoral components may be needed for all the patients of the population. For the autors, the choice of the technique (cement or cementless), and the choice of the optimal femoral stem (standard or custom-made implant) depends on two radiologic parameters: I.C.M. and I.E.F.; these parameters are defined and analysed.