The use of custom skull implants is a standard and effective method in my practice for almost all types of aesthetic skull augmentations. While any shape and size of custom skull implant can be designed that does not mean, however, that it can be successfully placed. The scalp is a tight enveloping soft tissue layer over the skull which can be stretched to accommodate an implant but has its limits. While there are no absolutes my general rule in skull implants up to 150ccs in volume or about 12 to 14mm maximum projection thickness can be placed in most patients
But when larger skull augmentations are needed the scalp must first be stretched to allow the larger implant size to be placed. This is a two stage skull augmentation procedure. A scalp tissue expander is initially placed. Over the ensuing 6 to 12 weeks, depending upon the desired implant volume, the patient fills the scalp tissue expander with incremental small volume additions. These at home inflations continue until the expander volume equals the skull implant design volume
When surgically placing larger skull implants preoperative thought has to be put into the implantation process. This mainly involves the scalp incision location and length. The smaller the scalp incision the harder it will be to get a single piece large skull implant through it. I have fount it helpful to consider designing the implant in a two piece approach. A split line is placed in the design and it is manufactured as two pieces. it is then placed one piece at a time through the scalp incision and reassembled once inside the scalp tissue pocket.
But when at the 2nd stage of skull implant placement the tissue expander is not the only thing that needs to be removed. The capsule that has formed on the bone must be lifted off and removed as well as releasing the capsule at the edges of the tissue expander. The largest scalp tissue expander is round measuring 15 x 15 mms. Skull implants are never completely round and have a more oblong shape just like the shape of the skull. Thus further scalp tissue pocket dissection is needed to enlarge the space needed for the skull implant.
The entire two stage skull augmentation process usually takes 2 to 3 months to complete. The lager the skull implant volume the more scalp tissue expander filling is needed.
Dr. Barry Eppley
Indianapolis, Indiana