When reconstructing defects in the skull is it safer and more cost effective to use a patients own bone or a custom made titanium plate

None listed

Cranial bone defects are often left following brain surgery usually to allow swelling of the brain to recover before subsequently re-implanting protective covering of the brain at a later time (cranioplasty). These procedure are performed anywhere over the the cranial vault, either unilaterally or bilaterally. The original piece of bone (autologous bone plate = bone flap) is placed in a sterile container and stored in a refrigerator at temperature of -40degrees celcius. Weeks or months later, when the brain is relaxed, the scalp well healed, and the patient’s medical condition permits, the individual is taken back to the operating theatre and the bone is reimplanted (A procedure known as an autologous cranioplasty). The aim of the procedure is to restore cosmesis and protection to the underlying brain and it can sometimes also improve neurological symptoms by unknown mechanisms. Unfortunately these aims are not always achieved and whilst technically straightforward the procedure is known to be associated with a number of complications. Two of the most significant of which are infection (such that the bone flap needs to be removed and replaced) and resorption (such that the protective function is compromised). A less severe but cosmetically significant complication is injury to the frontal branch of the facial nerve during cranioplasty leading to weakness of eyebrow elevation. Between 2004 and 2009 in Western Australia 164 patients required either a unilateral (n = 78) or bilateral (n = 86) decompressive craniectomy for trauma. Of those patients that survived 138 had a cranioplasty procedure and in this cohort there was a high rate of infection and bone flap resorption. Infection A number of reports have now documented the higher than expected incidence of infection following decompressive craniectomy and subsequent cranioplasty. Within the Western Australian state-wide neurosurgical service the overall infection rate for cranial procedures has been consistently audited at 1 – 2%, however within the post-traumatic craniectomy/cranioplasty cohort of 138 patients, sixteen (11.6%) had to have the bone flap removed because of infection. It is not known why the infection rate is so high but a number of reasons have been proposed e.g. skin colonisation whilst in hospital, factors relating to long-term storage of the bone flap, immune compromise following trauma and reoperation. Some studies have reported lower rates of infection when using custom made titanium or ceramic cranioplasty plates however, meaningful interpretation of the published literature is difficult because other studies have demonstrated precisely the opposite. Bone flap resorption The incidence of bone flap resorption has been reported between 10% and 50% Within our post traumatic cohort, 10% of the bone flaps were so severely resorbed that they needed to be replaced. A further 12% showed significant radiological resorption and whilst these were not replaced they could be adjudged to have failed because there is concern that they do not provide adequate protection. In each case of absolute cranioplasty failure (overall approximately 20%) the patient requires readmission, a second operation to remove the bone flap, prolonged antibiotic therapy (in the case of infection), a custom-made titanium plate constructed and readmission for a third surgical procedure. The question addressed in this study is whether it would be more efficacious and cost effective to insert a custom-made titanium cranioplasty as a primary procedure.