- Clinical Neurosciences Center, University of Utah, Salt Lake City, Utah, USA
Richard H. Schmidt
Clinical Neurosciences Center, University of Utah, Salt Lake City, Utah, USA
DOI:10.4103/2152-7806.127377Copyright: © 2014 Sayama CM. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
How to cite this article: Sayama CM, Sorour M, Schmidt RH. Dural adhesion to porous cranioplastic implant: A potential safety concern. Surg Neurol Int 18-Feb-2014;5:19
How to cite this URL: Sayama CM, Sorour M, Schmidt RH. Dural adhesion to porous cranioplastic implant: A potential safety concern. Surg Neurol Int 18-Feb-2014;5:19. Available from: http://sni.wpengine.com/surgicalint_articles/dural-adhesion-to-porous-cranioplastic-implant-a-potential-safety-concern/
Background:Patient-specific implants are used for cranioplastic skull reconstruction when large bone flaps must be replaced or where there are complex or critical contours, especially near the face. These implants have a low complication rate, with poor fit and postoperative infection being the most common complications. We report here a potentially serious hazard that may arise from the use of porous implants.
Case Description:A 45-year-old woman sustained severe head trauma in a motor vehicle accident that required urgent surgical intervention. Because of progressive resorption of her native bone flap, she underwent replacement of her native flap with a hard tissue replacement/patient-matched implant cranioplasty. Eight years later, she sustained a traumatic laceration over her vertex that necessitated removal of her cranioplastic implant because of persistent local infection. Intraoperatively, the dural flap was ingrowing and firmly adherent to the inside surface of the porous cranioplasty. After several failed attempts to remove the whole implant piecemeal, we attempted to dissect the dural flap from the brain surface to remove it together with the cranioplastic implant but exposure of the extensive cortical adhesions between the brain surface and the dural flap was compromised by the hard overlying cranioplastic implant. Despite our meticulous attempts to cut off these cortical adhesions, a perisylvian blood vessel was avulsed, resulting in intraparenchymal hemorrhage.
Conclusion:In this case, dural adhesion and ingrowth to the underside of the cranioplasty implant led to disastrous bleeding when the implant needed to be removed years after initial implantation.
Keywords: Adhesion, complication, cranioplasty, dura
Cranial reconstruction after neurosurgical procedures is common practice. Implants are intended for reconstruction and augmentation in craniofacial procedures to fill defects resulting from disease, surgical trauma, or traumatic injury. Numerous alloplastic materials are available for use when native bone cannot be used, including titanium mesh, polymethylmethacrylate (PMMA), silicone rubber, polyethylene, polytetrafluoroethylene, porous hydroxyapatite ceramics, and hard tissue replacement (HTR).[
Cranial reconstruction using computed tomography (CT)-generated patient-matched alloplastic implants has been used for medium and large defects in the upper craniofacial region. The polymer implants consist of either nonporous substance, such as polyetheretherketone (PEEK) or solid titanium metal, or a porous composite material composed of PMMA, polyhydroxyethylmethacrylate (PHEMA), and a calcium hydroxide coating. Porous cranioplasty implants have been applauded for their durability and ease of use as well as the ability to allow for vascular, soft tissue, and bone ingrowth – all of which supplement the acceptance of the foreign object. Additionally, porous cranioplasty implants have been reported in numerous studies to have low rates (0-11%) of complications such as infection and resorption.[
A 45-year-old female patient suffered a severe traumatic brain injury caused by a high-speed rollover motor vehicle accident. Her injuries included comminuted skull fractures, acute right-sided subdural hematoma, subarachnoid and intraparenchymal hemorrhages, and multiple brain contusions. On initial presentation at our facility, she was unconscious and intubated and had unequal pupils. She immediately underwent a large right decompressive hemicraniectomy, evacuation of subdural and right temporal intraparenchymal hematomas, and control of bleeding from lacerated anterior perisylvian arterial vessels. The dura, augmented with an autologous pericranial graft, was loosely closed over the injured brain, and the scalp was closed over a subgaleal drain.
Over the next 18 days, the patient made a good recovery and was discharged to inpatient rehabilitation. One month later, she underwent bone flap replacement using her native bone pieces, which had been sterilely preserved at −20°C. She was able to return home functionally independent, although she did not resume work as a school bus driver.
Three years later, because of progressive resorption of her cranial flap, she underwent replacement of her native bone with a porous plastic patient-specific implant (HTR PMI, W. Lorenz Surgical, Jacksonville, FL). At this surgery, her dura was noted to be completely healed and intact, and it was easily separated from the old bone pieces without being breached or having unusual bleeding. The patient recovered from this surgery uneventfully.
Examination and operation
Eight years later, the patient presented after sustaining a small traumatic laceration over her cranial implant at the vertex, which exposed a small portion of the plate. After 6 weeks, the wound had not healed completely despite her use of antibiotics and topical measures. On examination, there was exposed hardware but no erythema or signs of generalized infection. A CT scan of her head at that time showed no obvious radiographic complications [
Because there was clear contamination of the implant and the wound was not healing, we undertook removal of the implant, with a plan for delayed reconstruction. At surgery, the patient's original scalp incision was reopened, and the scalp flap was elevated without difficulty. After the cranial fixation hardware was removed, the skull implant was noted to be firmly adhered to the underlying dura. We began removing it piecemeal with Leksell rongeurs, beginning in the occipital–parietal area. Below the posterior edge of the implant it became clear that the dura had grown into and firmly adhered to the inferior 1 mm surface of the porous implant over the covered defect [
The adhesion could not be separated with Penfield instruments or curettes; hence, we resorted to a strategy of trying to separate the dura from the underlying brain to remove it piecemeal with the implant. Because of the previous trauma, there were numerous areas of dural adhesion to the brain, especially in the perisylvian frontotemporal region. Exposure of these cortical adhesions to the dura was further compromised by the hard, nonretractable nature of the overlying plastic implant. Despite our best efforts to clear these adhesions, an M3-M4 middle cerebral artery branch in the vicinity of her previous contusion and intraparenchymal hematoma was avulsed partway into the depths of the sylvian fissure. An operating microscope was used to explore this area, and hemostasis was obtained. Once all of the implant was removed, the resected dura was replaced with a large sheet of resorbable dural substitute (Durepair, Medtronic Corporation, Minneapolis, MN), and the scalp was closed.
The patient sustained a hemorrhagic infarct secondary to her adhesion-related vascular injury. She had an extended course in the neurosurgical critical care unit, with a left hemiparesis, pneumonia, deep vein thrombosis, and somnolence. She was discharged to a skilled nursing facility and, 6 weeks after her initial surgery, was readmitted for cranioplasty using a custom-made solid titanium implant (Synthes, West Chester, PA). Six months later, her wound was healed without further breakdown or infection. She had returned to her home but had significant residual hemiparesis and need for daily assistance.
During the past 15 years, neurosurgeons have used HTR PMIs for cranial reconstruction surgery. HTR PMI is characterized by the marked porosity of its surface, which allows for soft tissue and bone ingrowth. We have found no literature to date on the possible adverse affects of ingrowth.
We report the first case of dural adhesion and ingrowth to a porous HTR cranioplasty noted upon removal 8 years after implantation. This case demonstrates one potential concern when using porous cranioplasty material—dural adhesion to an implant requiring removal in a delayed fashion. Not only can this potentially damage the underlying brain parenchyma, but, as demonstrated by our case, can result in other catastrophic injuries, such as arterial avulsion when attempting to remove the cranioplasty material from the adhered dura and soft tissue below. In a review of the literature, we could identify no other cases requiring removal of porous cranioplasty in such a delayed fashion after initial implantation. Other than our case, the next longest duration to cranioplasty explantation was 37.6 months.[
Couldwell et al.[
In 1997, Roberson and Rosenberg[
Petersen and Hollins[
Nassiri et al.[
Although HTR PMI cranioplasties have had relatively good outcomes over short follow-up periods, the reported incidence of complications may be underestimated, as complications have previously been reported as late as 37.6 months (Nassiri et al.[
The authors thank Kristin Kraus, M.Sc., for editorial assistance in preparing this paper.
1. Couldwell WT, Chen TC, Weiss MH, Fukushima T, Dougherty W. Cranioplasty with the Medpor porous polyethylene flexblock implant. Technical note. J Neurosurg. 1994. 81: 483-6
2. Eppley BL. Craniofacial reconstruction with computer-generated HTR patient-matched implants: Use in primary bony tumor excision. J Craniofac Surg. 2002. 13: 650-7
3. Eppley BL, Kilgo M, Coleman JJ. Cranial reconstruction with computer-generated hard-tissue replacement patient-matched implants: Indications, surgical technique, and long-term follow-up. Plast Reconstr Surg. 2002. 109: 864-71
4. Eppley BL. Alloplastic cranioplasty. Oper Tech Plast Reconstr Surg. 2003. 9: 16-22
5. Kahraman S, Kayhall H, Kafadar A, Akboru M, Timurkaynak E. Clinical experience in cranioplasty with porous polyethylene implant. Turk Neurosurg. 2003. 13: 89-93
6. Liu JK, Gottfried ON, Cole CD, Dougherty WR, Couldwell WT. Porous polyethylene implant for cranioplasty and skull base reconstruction. Neurosurg Focus. 2004. 16: ECP1-
7. Nassiri N, Cleary DR, Ueeck BA. Is cranial reconstruction with a hard-tissue replacement patient-matched implant as safe as previously reported? A 3-year experience and review of the literature. J Oral Maxillofac Surg. 2009. 67: 323-7
8. Petersen T, Hollins R. Cranial reconstruction with computer-generated hard-tissue replacement patient-matched implants: Indications, surgical technique, and long-term follow-up. Arch Facial Plast Surg. 2003. 5: 533-4
9. Roberson JB, Rosenberg WS. Traumatic cranial defects reconstructed with the HTR-PMI cranioplastic implant. J Craniomaxillofac Trauma. 1997. 3: 8-13