This clinical pilot study will evaluate the use of a bioresorbable bone adhesive to improve cranial flap fixation at two study time points (at the time of fixation and 6 months). The aim of this Pilot Study is to demonstrate the safety and efficacy of the use of Tetranite for Cranial Flap Fixation (TN-CFF) to allow clinical study of the TN-CFF device in a greater number of patients.

The primary endpoint is safety during the post procedure follow up period. This endpoint will be evaluated through the rate of all serious adverse device and procedure related effects from the time of fixation to 6 months post-procedure. The secondary endpoints include efficacy evaluated through radiolucency data using CT imaging at the cranial flap cut lines and the change of radiolucency with respect to time, device related adverse events, flap immobility at time of fixation, six months and 12 months, evaluation of flap translation and patient reported outcome measures.

Inclusion Criteria:

• Subjects or representatives must have voluntarily signed the informed consent form before any study related procedures.
• Subjects can be any gender, but be between (and including) 18 and 75 years of age
• Subject is scheduled for a cranial procedure in the supratentorial location.
• Subject requires a procedure involving a Class I/clean wound (uninfected surgical wound in which no inflammation was encountered).
• Subject, and/or subject's family are able and willing to provide informed consent and HIPAA authorization.
• Subject is able and willing to meet all study requirements, including attending all post-index procedure assessment visits and radiological tests.

Intra-Operative Inclusion Criteria:

• Width of craniotomy kerf line < 3mm for more than 75% of the bone flap border

Exclusion Criteria:

• Subject requires a procedure involving a translabyrinthine, transsphenoidal, transoral approach, or any procedure that penetrates the air sinus or mastoid air cells. Note: Superficial penetration of mastoid air cells is not an exclusion if cells were appropriately sealed (e.g., bone wax).
• Subject has clinically significant hydrocephalus or clinical evidence of altered CSF dynamics.
• Subject has undergone a previous, open intracranial neurosurgical procedure in the same anatomical location. (Note: stereotactic biopsy was not exclusionary).
• Subject requires a craniectomy (the bone flap is not replaced during the current surgery).
• Subject had radiation treatment to the surgical site, or standard fractionated radiation therapy was planned post index-procedure. (Note: stereotactic radiosurgery prior to the planned index procedure was not an exclusion criterion.)
• Subject has a condition with anticipated survival shorter than six months.
• Subject has undergone chemotherapy treatment, excluding hormonal therapy, within three weeks prior to the planned index procedure, or use of intracavitary chemotherapy wafer (BCNU) was planned, or chemotherapy treatment was planned within two weeks after the index procedure was performed.
• Standard use of peri-operative steroids (i.e., corticosteroids) is permitted. Chronic steroid use (defined as daily use of corticosteroids for ≥ 8 weeks) for the purposes of reducing the side effects of chemotherapy and/or radiation therapy for cancer is not exclusionary unless the patient is deemed by the investigator to be suffering from steroid toxicity (i.e., Cushing's syndrome) manifested by symptoms and signs such as thin skin, striae, easy bruising, muscle atrophy, upper body obesity, severe fatigue, etc. Use of corticosteroids on a chronic basis (as defined previously) for purposes other than decreasing the symptoms of systemic chemotherapy is exclusionary unless those steroids were discontinued 4 weeks prior to the planned index procedure.
• Subject receives warfarin, heparin, other anticoagulant agents on a daily basis and pre-surgical, standard of care drug wash-out did not occur.
• Subject is pregnant, breast-feeding, or intended to become pregnant during the course of the study.

There is no plan to share IPD at this time. Study results will be published in a journal after study completion.