Widening pelvic bone width requires the placement of an implant along the anterior half of the iliac crest to expand its contour outward. Amongst all aesthetic implants this pelvic implant is unique. It does not call itself an implant, rather it is called an iliac plate and is of metallic composition. This is the only aesthetic augmentative implant throughout the entire face or body that is metal. Being metallic may partially account for why it is called a plate. But it is also called that because it looks like a plate as it is variation of an iliac fracture fixation plate.
The iliac plate is made of titanium and has three screws holes on both its front and back ends. Between these two ends is a raised hump of metal of varying thicknesses which is the true working part of the implant. This is what increases the pelvic bone width and is available in 15, 20, 35, 40 and 50mm projections. Despite the increased width projections the length of the plate and the screw holes only changes by 1 cm. (13cm for 15mm projection and 14cms at 50mms of projection) The width of the projection part of the implant changes more significantly being 12mm for 15mm of projection up to 42mm at 50mm of projection. (which is appropriate as the projection increases its width should similarly increase)
A very unique feature of the iliac plate is that the hump that creates the width increase is hollow. It is not solid metal but a shell of metal that creates the projection. This is for two reasons. It keeps the cost of the plate down (less titanium) and, more importantly, it makes it have a much lighter weight. Titanium is about 50% lighter than steel but very strong. It has the highest strength to weight ratio of any metal and is corrosion resistant. The weight of the plates averages 250 grams to 450 grams (less than 1 lb) so they are fairly light weight.
Screw fixation to the iliac crest is essential given its anatomic location on the side of the bone and the external forces to which it will be exposed after placement. Like iliac fracture plates the plate and screw holes are of 3.5mm thicknesses. The plate holes are threaded and locking screws are used for them. A large number of screw lengths are available to use and the screws must be bicortical in placement.Typical lengths used are 24 to 30mms. Much longer screws are available to put through the main body of the implant but the need for that is rare.
While there is an anterior and posterior plate extension with screw holes it is not necessary to fill all the available holes with screws. Two to three screws is all that needed for each plate. With bicortical screw placement and threaded locking screws good fixation of the plate to the bone is achieved. In almost all cases the posterior plate extension and holes is not needed and may need to be partially removed. This can easily be done with the proper tool. (Hercules 3.5mm plate cutter)
Dr. Barry Eppley
World-Renowned Plastic Surgeon