That's not always an ideal situation, and can lead to complications. New research coming out of the Johns Hopkins University could provide an alternative, creating custom-made, 3D-printed implants from a mixture of plastic and bone powder.

The need for replacement facial and head bones is greater than you might think, with an estimated 200,000 people requiring replacement implants as a result of surgery, trauma or birth defects. Traditionally, surgeons remove bone from the patient's leg, cutting it into the shape of the required implant.

Unsurprisingly, that option doesn't always pan out too well, with the straight nature of the leg bone making it difficult to shape effectively. Combine that with the trauma of having part a bone removed from your leg, and it's clear that a better alternative is called for.