Cranioplasty with neovascularized autogenous calvarial bone

Clinical outcomes in cranioplasty: risk factors and choice of reconstructive material

BACKGROUND

Continuing advances in cranioplasty have enabled repair of increasingly complicated cranial defects. However, the optimal materials and approaches for particular clinical scenarios remain unclear. This study examines outcomes following cranioplasty for a variety of indications in patients treated with alloplastic material, autogenous tissue, or a combination of both.

METHODS THE AUTHORS CONDUCTED

a retrospective analysis on 180 patients who had 195 cranioplasties performed between 1993 and 2010.

RESULTS

Materials used for cranioplasty included alloplastic for 42.6 percent (83 of 195), autologous for 19.0 percent (37 of 195), and both combined for 38.5 percent (75 of 195). Mean defect size was 70.5 cm. A subset of patients had undergone previous irradiation (12.2 percent; 22 of 180) or had preoperative infections (30.6 percent; 55 of 180). The most common complication was postoperative infection (15.9 percent; 31 of 195). Factors that significantly predisposed to complications included preoperative radiation, previous infection, and frontal location. Preoperative radiation was the strongest predictor of having any postoperative complications, with an adjusted odds ratio of 6.91 (p < 0.005). Irradiated patients (OR, 7.96; p < 0.05) and patients undergoing frontal cranioplasties (OR, 2.83; p < 0.05) were more likely to require repeated operation. Preoperative infection predisposed patients to exposure of hardware in alloplastic reconstructions (OR, 3.13; p < 0.05).

CONCLUSIONS

Despite the evolution of cranioplasty techniques and materials, complications are not uncommon. The choice of reconstructive material may modify the risk of developing postoperative complications but appears less important than the clinical history in affecting outcome.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Risk, III.

A treatment algorithm for patients with large skull bone defects and first results

Large skull bone defects resulting from craniotomies due to cerebral insults, trauma or tumours create functional and aesthetic disturbances to the patient. The reconstruction of large osseous defects is still challenging. A treatment algorithm is presented based on the close interaction of radiologists, computer engineers and cranio-maxillofacial surgeons. From 2004 until today twelve consecutive patients have been operated on successfully according to this treatment plan. Titanium and polyetheretherketone (PEEK) were used to manufacture the implants. The treatment algorithm is proved to be reliable. No corrections had to be performed either to the skull bone or to the implant. Short operations and hospitalization periods are essential prerequisites for treatment success and justify the high expenses.

LONG-TERM OUTCOME OF SUBCUTANEOUSLY PRESERVED AUTOLOGOUS CRANIOPLASTY

OBJECTIVE

Decompressive craniectomy for intracranial hypertension mandates later cranioplasty. Autologous cranioplasties can be preserved either by freezing or placement in a subcutaneous pocket. There are few data on the long-term follow-up of patients treated in such a fashion.

METHODS

A retrospective study was conducted on 100 consecutive patients who underwent decompressive craniectomy and placement of the bone flap in a subcutaneous pocket in the abdominal wall between 2000 and 2005. Initial diagnosis, Glasgow Coma Scale score on admission, complications, and Glasgow Outcome Score were recorded.

RESULTS

Of the 100 patients who underwent autocranioplasty, the primary diagnosis was traumatic brain injury (76%), subarachnoid hemorrhage (17%), primary intracerebral hemorrhage (3%), and tumor (4%). The mean age of the sample was 39 years (age range, 10–72 years). The mean follow-up duration was 25 months. The average Glasgow Coma Scale score on admission was 7. Eight patients died before replacement of the bone flap. The average time between craniectomy and replacement of bone flap was 42 days. The mean Glasgow Outcome Score was 4 at the time of the 1-year follow-up evaluation. Seven of the 79 patients (9%) for whom 1-year review data were available had a cosmetic result that was unacceptable and required removal of the flap (bone flap infections in 5 patients, unacceptable bone flap resorption in 2 patients)

CONCLUSION

Our study indicates that storage of a cranioplasty flap in a subcutaneous pouch in the abdominal wall has a favorable long-term outcome.

Osteocutaneous Flap Prefabrication in Rats

Composite tissue defects may involve skin, mucosa, muscle, and bone together or in combinations of two or three of these tissues. Defects involving bone and skin are frequently encountered. Osteocutaneous flaps may be used to reconstruct these composite tissue defects. Sometimes, it is not possible to obtain a vascular osteocutaneous flap. Another way of producing an osteocutaneous flap that has the desired feature is prefabrication. Prefabrication of osteocutaneous flaps can be performed in two ways: (1) a vascularized osseous flap may be grafted with skin and (2) an osteocutaneous flap can be prefabricated by implanting an osseous graft into an axial island flap. There are many articles describing osteocutaneous flap prefabrication, but there is no comparison of both methods in the literature. As an experimental model for osteocutaneous flap prefabrication, rat tail bone was chosen. For the experiments, five groups were formed. Each group contained 10 rats. In the first experimental group, a vascularized osseous segment was skin grafted and an osteocutaneous flap was prefabricated. In the second experimental group, an osseous graft was implanted into an axial skin flap. To compare viability of skin and bone components of the two prefabrication groups, vascularized tail bone was elevated with overlying skin in the third group, a bone flap was elevated in the fourth group, and a skin flap that had been prefabricated by using vascular implantation was elevated in the fifth group. The authors examined five rats in each group by microangiography at the end of 4 weeks. On microangiographic analysis, all groups showed patency of vascular pedicles. There was no difference among the groups from the point of view of vascular patency and bone appearance. Bone scintigraphy was performed on the five rats in each group. On bone scintigraphic scans, the bone component of flaps was visualized in all groups except for group 5. The mean radioactivity value on the flap side was 10,362 +/- 541.1 in group 1, 10,241 +/- 1173 in group 2, 10,696 +/- 647.1 in group 3, and 10,696 +/- 647.1 in group 4. When the radioactivity values on the flap side were compared, no statistically significant difference among groups was seen, except for group 5 (p < 0.05). To evaluate bone metabolic activity, the bone component of flap and remaining last tail bone was harvested and the radioactivity of each specimen was measured with a well-type gamma counter. The parameter of percentage radioactivity in counts per minute per unit per gram of tissue was calculated. The value of the bone component of the flap side and the value of normal bone were estimated and results were compared. The mean result was 0.86 +/- 0.08 in group 1, 0.88 +/- 0.07 in group 2, 0.87 +/- 0.07 in group 3, and 0.81 +/- 0.04 in group 4. The difference among all groups was not statistically significant. Histologic examination was performed on all rats in each group and demonstrated that the bony component was viable, showing a cellular bone marrow, osteoblasts along bony trabeculae, and vascular channels in bone-containing groups. There were no significant microangiographic, histologic, or scintigraphic differences between the two experimental methods.

Prefabricated galeal flap based on superficial temporal and posterior auricular vessels

Scalp layers are widely used in reconstructive procedures. The authors used prefabricated galeal flaps based on the superficial temporal or postauricular vessels for ear, cheek, mandible, and cranium reconstructions in three cases. In case 1, synchronous beard and ear reconstructions were accomplished by using the temporoparietal and retroauricular flaps. In case 2, a buccomandibular defect was reconstructed by transposing the supra-auricular and retroauricular galea with prefabricated bone and skin. In case 3, an epidural hematoma in the left frontoparietal area was evacuated after a circular craniectomy. The harvested bone was not put back on the defect area but buried between the periosteal and galeal layers because of brain edema. These layers were raised as an osteogaleoperiosteal flap and transposed onto the defect area after 7 weeks. When used with a prefabrication method, scalp layers offer versatile options for repairing composite defects of the head region. A galeal flap based on the posterior auricular vessels is practical and reliable in reconstructive procedures. The authors suggest that this flap is an option in cases in which the temporoparietal fascia artery or the superficial temporal artery is not available. Prefabrication of the harvested cranial bone inside the adjacent tissues offers several advantages in that a viable bone is provided at the end of the procedure, intervention at a distant area is avoided, the graft is placed on osteogenic tissue (periosteum) that is also transposed onto the defect, and sophisticated procedures such as microsurgical techniques are not needed.

Long-term results following reconstruction of craniofacial defects with titanium micro-mesh systems

INTRODUCTION

Reconstruction of craniofacial defects can be carried out with autogenous tissue (calvarium, rib, iliac crest), allogeneic implants (AAA-bone, lyophilized cartilage) or alloplastic material (methacrylate, hydroxyapatite, titanium implants and mesh systems). Selection of the implant material used for reconstruction is still controversial.

MATERIAL AND METHODS

At the Department of Oral and Maxillofacial Surgery, Kantonsspital Luzern, 20 patients with defects in the craniofacial and/or orbito-ethmoidal region have been treated using titanium micro-mesh between 1991 and 1998. Two different mesh systems, micro-titanium augmentation mesh and dynamic mesh, have been used for bony reconstruction in non load-bearing areas. The defects were caused by acute trauma, osteomyelitis of the frontal bone and previous operations. The titanium micro-mesh was used with the following indications: (1) immediate reconstruction in the primary treatment of comminuted fractures with bone loss in non load-bearing areas, (2) treatment of contour irregularities (possibly in combination with bone or cartilage grafts). All patients were followed up clinically and radiographically at quarterly intervals for a year.

RESULTS

No wound infections, exposures or loss of the mesh have been observed. Long-term stability of the reconstructions was excellent. When walls of the paranasal sinuses were reconstructed complete repneumatisation took place.

CONCLUSIONS

Advantages of this reconstructive technique are: (1) universal applicability (craniofacial, orbital, sinus defects, comminuted fractures); (2) stable 3-D reconstruction of complex anatomic structures were easily performed; (3) immediate availability with no donor site morbidity as bone or cartilage grafts were not necessary; (4) combination with bone or cartilage grafts is possible; and (5) very low susceptibility to infection.