He is also credited for the invention of a mechanized trephine for corneal procedures. Obtaining a bone biopsy is accomplished by using a bone biopsy trephine. Bone marrow samples can be obtained by aspiration and trephine biopsy. The best location of the trephine is the floor of sinus or through brow ridge. The two tubing pieces are inserted through trephine and sutured. A second trephine is then used to remove a similar-sized portion of the patient's cornea. In modern eye surgery, a trephine instrument is used in corneal transplant surgery. A different, larger trephine needle is inserted and anchored in the bony cortex. If there is possibility of development of osteomyelitis, trephine should be made inferiorly.