ABSTRACT
Cranioplasty following extended, decompressive craniectomy is a formidable challenge and its complexity increases with the size of the bone defect. Several techniques and methods are described for preservation and sterilization of craniectomy bone flap, each has its own advantage and disadvantages. In this report the authors describe a simple and cheap method for preservation of large craniectomy bone flaps. To evaluate the technique of preservation of large craniectomy bone flap in the freezer at -18°C for long periods of time, by microbiological and histological examination. This prospective study was carried out at King Khalid University Hospital, College of Medicine, King Saud University, during the period January 2001 to December 2008. Twenty-four patients had decompressive craniectomy for intractable brain oedema due to different pathology. A protocol was designed to prepare the removed bone flap for preservation in domestic freezer at -18°C. Microbiology swabs and histology specimen were taken from 14 bone flaps and sent for microbiological and histological examination to check both sterility and viability of the bone flaps after long periods of preservation. During the study period 24 decompressive craniectomy bone flaps were preserved, 15 of them were bifrontal decompressive craniectomy. Sixteen bone flaps were reapplied to their patients while 8 flaps were kept in freezer for long periods of time after expiry of donor patients. The dimensions of bone flaps ranged from 5 x 7 cm to 13 x 25 cm with a mean surface area of 228 cm[2]. Duration of preservation ranged from 60 - 1920 days, mean 313. Fourteen bone flaps were examined histologically and microbiologically, all of them showed no bacterial contamination and were viable, except one flap was not viable. Mature lamellar bone was seen in 5 specimens preserved for [60, 60, 90, 120 and 150 days], mostly viable bone was seen in 4 specimens preserved for [360, 390, 480 and 900 days], focal loss of bone was seen in 4 specimens kept for [390, 630, 720 and 780 days], and one specimen was kept in freezer 1920 days and showed no viable bone. The follow-up period after cranioplasty ranged from 5 months to 6 years, mean 11 months. One patient developed superficial wound infection which was treated with antibiotics and repeated dressings. Another patient developed partial resorption of the bone flap which was treated conservatively as spontaneous bone regrowth appeared a few months later. Preservation of bone flap in the freezer at -18°C is very simple, cheap and safe and is available in all hospitals. Bone flaps preserved using our technique remains viable and sterile for periods of up to 12 months