Abstract
A diverse range of techniques is available for reconstruction of full-thickness calvarial defects and the optimum substrate for cranioplasty remains unproven. During a 9-year period, 149 patients underwent insertion of 151 custom-made titanium cranioplasties using the same technique. Data relating to patient demographics, indication for cranioplasty, and site and size of the defect were collected from the clinical records. Patients were followed up in all cases for a mean of 1 year 2 months (range 7 days to 8 years 8 months). Early complications requiring intervention were experienced in 7% and included seroma, haematoma, and continued bleeding necessitating implant removal in one patient. One death occurred at 3 days post-operation due to haemorrhagic stroke. Late self-limiting complications such as seroma were experienced in 19% of patients, however complete failure requiring implant removal was seen in only 4% of cases. Infection was the cause of failure in all cases. A comprehensive literature review was carried out and data abstracted to compare reported failure rates in other techniques of full-thickness cranial reconstruction. This review shows that custom-made patient-specific titanium cranioplasties compare very favourably to the other published techniques and remain a tried and tested option for reconstruction of all sizes of full-thickness calvarial defect.
Full-thickness calvarial defects continue to challenge reconstructive surgeons. Defects of the cranium can arise from a wide range of pathological processes or from therapeutic interventions. Reconstruction of these defects is necessary to restore normal craniofacial cosmesis and to protect the otherwise exposed brain from trauma. The ideal cranioplasty technique should produce excellent aesthetics, the ability to withstand direct trauma without failure, have minimal effects on the patient in terms of morbidity, and be stable in the long term. Although there are reports of cognitive improvement following cranioplasty and resolution of the so-called ‘syndrome of the trephined’, currently it is the cosmetic and protective benefits of reconstructing the cranium that are the motivation for undertaking this type of surgery.
Cranioplasty is one of the oldest known surgical procedures, with archaeological evidence of ancient Incans using gold to reconstruct trephination holes around 3000 BC. The earliest written account of cranioplasty dates from 1505 when Ibrahim bin Abdullah, an Ottoman-era military surgeon, advocated the use of a cranial xenograft from a goat or dog. In 1561, in Observationes Anatomicae , the Italian Fallopius described cranioplasty with a gold Plate. As a result of this long history and as a testament to the complexity of cranial reconstruction, various techniques have been developed to repair these defects using autografts, allografts, and various biomaterials including gold, stainless steel, vitallium, tantalum, titanium, polythene, methylmethacrylate, polyether ether ketones (PEEK), acrylic, ceramics, and bioactive glass, used alone or in combination. There is no ideal technique as each method has its limitations. When autografts are utilized, problems are encountered with satisfactory graft contour and long-term stability, particularly as regards resorption, along with potential donor site morbidity. High infection rates and material failure have been reported with biomaterials.
This study is a retrospective review of early and late complications following cranioplasty in all patients who underwent custom-made titanium plate reconstruction of full-thickness calvarial defects carried out at a tertiary level hospital in London, UK.
Materials and method
In this retrospective study, operation records and the laboratory database were used to identify all patients who underwent titanium cranioplasty using a patient-specific custom-made implant at a tertiary level hospital in London between 2001 and 2010. Only patients with full-thickness calvarial defects were included in this study. Clinical records were analysed and data collected on patient demographics, age at operation, indication for cranioplasty, interval between acquisition of defect and reconstruction, length of inpatient stay, length of follow-up, defect site, defect surface area, complications arising early (defined as occurring during admission) and late complications (defined as arising after discharge). Postoperative follow-up was achieved in all cases; in six cases, the patient’s general practitioner was contacted to identify complications as the hospital records were incomplete.
A literature search was undertaken of PubMed and Science Direct using the search terms ‘cranioplasty’, ‘calvarial reconstruction’, ‘cranial reconstruction’, ‘cranial defect’ and ‘calvarial defect’. Returned search articles and their references were used to identify articles reporting complications of cranioplasty. Data were then abstracted from these studies to identify the reported failure rates for the commonly used cranioplasty materials to be used as comparison for the outcome of cranioplasties in the series from the study hospital. Criteria applied to studies for data abstraction were the following: (1) case series reporting the outcome in at least seven patients; (2) publication date during or after 1995; (3) the reported reconstruction method was for full-thickness cranial defects in humans; (4) the failure rate pertaining to each reported method was clearly stated or calculable from the published data. Series of composite reconstruction, i.e. cranioplasty and simultaneous microvascular scalp reconstruction, and case series of allograft cranioplasty were not included in the literature review. The follow-up period and defect size were also recorded if stated or calculable from the data presented in the papers.
Manufacture of implant and surgical technique
DICOM data from a fine cut craniofacial computed tomography (CT) scan (1 mm slice, 0° gantry angle) is converted to STL file format to generate a stereolithographic model using rapid prototyping. This model of the defect and surrounding calvarium is invested in plaster and used in a hydraulic press to cold form 0.8-mm thick titanium sheet. The moulded sheet is trimmed to leave a 1 cm margin of titanium to contact the bony edges of the defect. Several holes are drilled at the periphery of the plate to allow screw insertion for fixation, and multiple holes drilled in the central part of the plate to allow extradural fluid collections to drain via vacuum drains. The holes drilled centrally also allow placement of looped PDS sutures hitching the dura to the plate to reduce the extradural space and prevent fluid collections from exerting a space-occupying lesion effect on the brain parenchyma. After polishing, the cranioplasty plate is anodized and treated with nitric acid. Sterilization is by autoclave prior to insertion into the patient.
Surgical access predominantly utilizes existing scars; however if previous incisions have been made in an unfavourable fashion, a bicoronal approach is used to maximize the vascularity of the scalp. The titanium cranioplasty implant is secured with 2-mm titanium screws and the scalp closed in layers with vacuum drains inserted between the scalp and cranioplasty plate. Drains are usually removed at 48 h. A tight head bandage is applied and left in situ until review at 10 days post operation ( Fig. 1 ).
Results
For a period of 9 years between August 2001 and August 2010, 149 patients underwent insertion of 151 custom-made titanium cranioplasties for reconstruction of full-thickness calvarial defects. Two patients had bilateral defects reconstructed with individual plates.
Seventy-two percent of the patients in this series were male. The average age at operation was 36 years (median 37, mode 56, range 6–78 years). Four of the cranioplasties were carried out as immediate reconstructions following tumour resection; the remainder involved either congenital deformity or delayed reconstruction carried out at an interval following initial craniectomy. The injury date for 13 patients was unknown. For the remaining 133 patients, the average interval between cranial defect and insertion of the cranioplasty was 2 years 1 month (median 1 year, mode 10 months, range 2.5 months to 28 years 9 months). The mean follow-up to discharge was 1 year 2 months (median 5 months, range 7 days to 8 years 8 months). The average length of the inpatient episode was 6.4 days (median 4, mode 4, range 2–121 days).
Data on the defect size was accurately calculated using the volume rendering function of the CT scan software (Centricity PACS/AW Suite; GE Healthcare). Due to a change in software used in the hospital we were unable to calculate the accurate surface area for 28 patients. Of the remaining 123 patients, the average defect surface area was 67.5 cm 2 (median 65, mode 78.4, range 5.3–173.7 cm 2 ). Very large defects were reconstructed in this group of patients, with 45 implants (36%) being inserted for defects with a surface area greater than 80 cm 2 ( Table 1 ). The sites of the defects are illustrated in Fig. 2 .
| Defect surface area, cm 2 | Number of defects |
|---|---|
| 0–40 | 32 |
| 41–80 | 46 |
| 81–100 | 27 |
| >100 | 18 |
Indications for cranioplasty are summarized in Table 2 . Decompressive craniectomies following trauma, stroke, and intracranial infections and following tumour removal were the most common indication for the original craniectomy (collectively 55%). Infected bone flaps (21%) from previous conventional neurosurgery and following tumour resection involving bone (11%) were the next most common indications, with the remainder of indications comprising post-traumatic defects, post-infection defects, congenital deformity, growing fracture, and deformity as a result of multiple craniotomies.
| Indication | Number of patients |
|---|---|
| Congenital defect | 3 |
| Post tumour resection | 17 |
| Post infection | 6 |
| Infected bone flap | 32 |
| Post decompressive craniectomy | 82 |
| Post trauma | 7 |
| Growing fracture | 1 |
| Post operation deformity | 1 |
Early complications, defined as occurring before discharge, are summarized in Table 3 . One patient died 3 days postoperatively as a result of brainstem haemorrhagic stroke. This patient had undergone bilateral fronto-temporoparietal decompressive craniectomies (defect sizes of 81 cm 2 and 105 cm 2 ) following a fall down a flight of stairs. The patient subsequently had a brainstem haemorrhage on the third postoperative day confirmed on CT scan, and life-supportive measures were withdrawn. One patient was complicated by inadequate fit of the implant. This patient underwent immediate reconstruction following meningioma resection and had a larger defect than was planned for, resulting in the cranioplasty implant not covering the margins of the defect completely. This patient subsequently had a late complication of infection requiring removal of the implant. Significant postoperative bleeding complicated four patients following cranioplasty. One patient had a haematoma that was aspirated under local anaesthetic. One patient was taking aspirin which had not been stopped prior to insertion of the cranioplasty and experienced bleeding 3 days post-operation requiring evacuation of haematoma in theatre under a general anaesthetic.
| Complication | Number | Notes |
|---|---|---|
| Haematoma | 4 | Three required evacuation in theatre |
| Cranioplasty removal | 1 | Prolonged haemorrhage required removal |
| Infected surgical site | 1 | 2 weeks vancomycin (follow-up 514 days, no further infection) |
| Seroma | 1 | Required drainage in theatre |
| Death | 1 | Haemorrhagic stroke 3 days post operation |
| Sepsis of unknown cause | 1 | No further complications recorded |
| Inadequate fit of implant | 1 | Bony resection larger than planned |
One patient who was normally taking warfarin for previous thromboembolic stroke had been covered with low molecular weight heparin for the procedure. Warfarin was restarted on the first postoperative day and the patient experienced bleeding on day 5 post-operation requiring drainage of haematoma under general anaesthetic in theatre. One further patient experienced prolonged bleeding that required return to theatre and removal of the cranioplasty to evacuate extradural haematoma and obtain haemostasis. This patient subsequently had successful re-insertion of the cranioplasty 2.5 months later without complication. One patient had a seroma which required drainage in theatre. One patient developed sepsis of unknown cause that settled with antibiotics. This patient has not subsequently developed any problems with the cranioplasty site during a follow-up period of 514 days. The overall early complication rate in this group of patients was 7% with a mortality of 0.67%.
Late complications, defined as occurring after discharge, are shown in Table 4 . These included seroma, haematoma, and infection. Seroma was noted in 22 patients. This was managed conservatively and settled without intervention in 21 patients. One patient required aspiration of seroma in the outpatient clinic. One patient with no predisposing co-morbidities who underwent reconstruction of a 173.1-cm 2 defect developed swelling of the cranioplasty site 4 days following discharge from which haematoma was uneventfully aspirated; the patient did not require re-admission to hospital. Six of the 149 patients developed late infection and this required cranioplasty removal in all cases.
| Complication | Number | Notes |
|---|---|---|
| Seroma | 22 | All settled by 3 months post operation |
| Haematoma | 1 | Required aspiration in clinic |
| Infection | 6 | All required removal of implant |
Removal of the cranioplasty took place within a year of placement in four patients. Four of the infections occurred in patients who had had a previous infection at the defect site; three patients had experienced infected craniotomy bone flaps and one patient had had an infection of an acrylic cranioplasty that had been placed at another unit some 4 years previously. Two patients had late infections occurring more than 2 years from insertion. The overall late complication rate in this series was 19%, although the majority of these complications were due to seroma, which settled spontaneously in all but one case. The overall failure rate of cranioplasty in this group of patients was 4%. The characteristics of the late infections group are summarized in Table 5 .
| Age, years | Gender | Immediate or delayed | Previous infection | Indication for craniectomy | Number of previous interventions | Surface area (cm 2 ) | Site of defect | Insertion to removal interval (days) |
|---|---|---|---|---|---|---|---|---|
| 56 | M | Delayed | No | Decompressive | 1 | 96.7 | Lateral neurocranium | 227 |
| 26 | M | Delayed | Yes | Post tumour resection | 4 | 49.3 | Lateral neurocranium | 92 |
| 56 | F | Immediate | No | Post tumour resection | 0 | Unknown | Lateral neurocranium | 51 |
| 31 | M | Delayed | Yes | Infected bone flap | 3 | 83.3 | Lateral neurocranium | 1010 |
| 71 | F | Delayed | Yes | Infected bone flap | 2 | 106.1 | Bifrontal | 2817 |
| 34 | M | Delayed | Yes | Infected bone flap | 2 | 43.8 | Lateral neurocranium | 93 |
The most significant complication of cranioplasty is failure, which is either resorption of grafted bone or removal of the prosthesis due to infection or material failure. A comprehensive review of the literature was carried out and data from reported case series were abstracted to compare the results of this case series with other techniques. The analysis of the literature yielded 53 case series that fulfilled the criteria for analysis. The majority of the case series analysed are retrospective, and data regarding defect size and follow-up were incomplete in several series. Table 6 summarizes the failure rates of these 53 papers.
| Author and year | Material | Cases, n | Defect size | Follow-up | Significant complications |
|---|---|---|---|---|---|
| Akan et al. 2011 | PMMA | 17 | 3 × 3 cm to 16 × 7 cm | 36 h to 3 years (mean 1.6 years) | 1 (6%) removed (infection); 1 mortality (MI) |
| Barone and Jimenez 1997 | Split calvarium | 16, paediatric | Not stated | 0.79–7.9 years (mean 2.3 years) | No failures |
| Blum et al. 1997 | PMMA | 75, paediatric | Mean 36 cm 2 | 3–16 years (mean 10 years) | 17 (23%) removed (12 infections, 3 dislodgements, 2 implant fractures) |
| Burstein et al. 1999 | HA cement | 10 | 1 × 1 cm to 2 × 10 cm | Not stated | No failures |
| Chao et al. 2009 | Demineralized bone matrix + polylactic acid/polyglycolic acid mesh | 11 | 6.6–80 cm 2 (mean 30.8) | 13.4–41.8 months (mean 29.3 months) | No failures |
| Chen and Wang 2002 | Perforated demineralized allogeneic bone | 10 | 8 × 6 cm to 11 × 12.5 cm | 2.5–3 years | No failures |
| Cheng et al. 2008 | PMMA | 23 | Not stated | Not stated | 2 (6.25%) removed (infection) |
| Cryopreserved bone flap | 52 | 7 (13.5%) removed (infection) | |||
| Choi et al. 1998 | Coraline HA cement/tantalum mesh | 10 | Not stated | 1–43 months (mean 26 months) | 1 (10%) removed (infection) |
| Cohen et al. 2004 | Polylactic acid absorbable plates/carbonated apatite bone cement | 34 | 1 × 2 cm to 15 × 15 cm | 3–60 months (mean 24.4 months) | No failures |
| Durham et al. 2003 | HA cement/tantalum mesh | 8 | 40–196 cm 2 (mean 138) | 2–33 months (mean 11.4 months) | 2 (25%) removed (infections) |
| Ducic 2002 | HA cement/titanium mesh | 20 | 10–156 cm 2 | 6 months–3 years | No failures |
| D’Urso et al. 2000 | PMMA | 30 | Not stated | Not stated | 1 (3%) removed (infection) |
| Eppley 2002 | HTR (immediate cranioplasty) | 7 | Not stated | Mean 2.6 years | No failures |
| Eppley et al. 2002 | HTR (delayed cranioplasty) | 14 | >150 cm 2 | 1–3 years | No failures |
| Eufinger et al. 2005 | Titanium CAD/CAM manufactured | 143 | Not stated | Not stated | 14 (9.8%) removed (infection) |
| Goh et al. 2010 | PMMA | 31 | 6 × 4 cm to 14 × 13 cm | 8 months–5 years | 3 (9.7%) removed (infection) |
| Gooch et al. 2009 | Preserved autologous bone flap | 57 | Not stated | Minimum 4 months | No failures; 16 (26%) required second operation |
| Titanium | 3 | No failures | |||
| PMMA | 2 | No failures | |||
| Gosain et al. 2009 | Bioactive glass | 3, paediatric | Not stated | Mean 3.3 years | No failures |
| Demineralized bone matrix | 8, paediatric | 1 (33%) removal (inadequate bone replacement) | |||
| Prefabricated polyethylene (Medpore) | 3, paediatric | No failures | |||
| Grant et al. 2004 | Fresh frozen bone flap | 40, paediatric | 14–147 cm 2 (mean 99.4) | 6 months–6 years (mean 4.8 years) | 20 (50%) failures (bone resorption) |
| Greene et al. 2008 | Particulate cranial graft | 38, paediatric | 5–250 cm 2 (mean 66.5) | 0.5–18 years (mean 6.5 years) | 1 (3%) failure (resorption) |
| Hanasono et al. 2009 | PEEK | 6 | 6 × 7 cm to 10 × 20 cm | 3–16 months (mean 3 months) | No failures |
| Inamasu et al. 2010 | Cryopreserved bone flap | 31 | Mean 46.5 months | 4 (13%) removed (infection) | |
| Subcutaneous stored bone flap | 38 | Mean 52.4 months | 2 (5%) removed (infection) | ||
| Inoue et al. 1995 | Split calvarium | 10 | 5 × 5 cm to 10 × 14 cm | 2–43 months (mean 16.9 months) | No failures |
| Iwama et al. 2003 | Frozen bone flap | 47 | Not stated | 14–147 months (mean 59.2 months) | 2 (4%) removed (infection/resorption) |
| Jho et al. 2007 | Ethylene oxide gas sterilized bone flap | 103 | Not stated | 1–63 months (mean 14 months) | 8 (7.8%) removed (infection/resorption) |
| Joffe et al. 1999 | Titanium | 148 | Not stated | Not stated | 1 (<1%) removal (infection) |
| Josan et al. 2004 | Bone flap | 16, paediatric | Not stated | 3 months–15 years (mean 18 months) | 3 (21%) removed (infection) |
| Split calvarial graft | 8, paediatric | No failures | |||
| PMMA | 3, paediatric | No failures | |||
| Titanium | 1, paediatric | No failures | |||
| Kriegel et al. 2007 | PMMA | 36 | Not stated | Mean 44 months | 2 (5.6%) removed infection |
| Tutoplast bone flap | 25 | Not stated | Mean 15 months | 2 (8.4%) removed (infection/resorption) | |
| Kshettry et al. 2012 | Titanium mesh | 12 | 4.5 × 3 cm to 8.6 × 8.6 cm | Mean 13.2 months | 2 (20%) removed (infection) |
| Lee et al. 1995 | Split calvarium | 8 | Not stated | 6–36 months (mean 17.8 months) | 1 (12.5%) fixation plates removed (infection) |
| Lee et al. 2009 | Frozen bone flap | 91 | Not stated | Not stated | 5.5% infection |
| In situ moulded PMMA | 23 | 13% infection | |||
| PMMA | 17 | 5.8% infection | |||
| Lin et al. 2012 | Polyethylene (Medpore) | 9 | 91–231 cm 2 (mean 152) | 0.5–22.4 months (mean 6.9 months) | No failures |
| Marchac and Greensmith 2008 | PMMA | 32 | Not stated | 2–16 years (mean 8.2 years) | 4 (12.5%) removed (3 infections/1 implant fracture) |
| Matsuno et al. 2006 | Cryopreserved bone flap | 54 | Not stated | 0.36–12.1 years | 14 (25.9%) removed (infection) |
| In situ moulded PMMA | 55 | 7 (12.7%) removed (infection) | |||
| Custom-made PMMA | 3 | 1 (33.3%) removed (infection) | |||
| Titanium mesh | 77 | 2 (2.6%) removed (infection) | |||
| Custom-made ceramics | 17 | 1 (5.9%) removed (infection) | |||
| Mokal and Desai 2011 | High density porous polythene | 7 | 4–> 8 cm diameter | 6 months–3 years (mean 18 months) | No failures |
| Morina et al. 2011 | Subcutaneously preserved bone flap | 75 | Mean 9 × 11 cm | Not stated | 2 (3%) removed (infection) |
| Movassaghi et al. 2006 | Subcutaneously preserved bone flap | 52 | Not stated | Not stated | 2 (4%) removed (infection) |
| Nassiri et al. 2009 | HTR | 21 | Not stated | 0.5–55.4 months (mean 3 months) | 4 (19%) removed (1 exposure/3 infections) |
| Ono et al. 1999 | HA ceramic | 9 | Major axis >10 cm | Not stated | No failures |
| Pang et al. 2005 | HA cement + macropore superstructure | 15 | 6.25–42.5 cm 2 | 2.2–4.2 years (mean 2.9 years) | No failures |
| Paşaoğlu et al. 1996 | Subcutaneous bone flaps | 27 | Not stated | 6–26 months (mean 10 months) | No failures |
| Rogers et al. 2011 | Exchange calvarial graft | 20, paediatric | 5.4–270 cm 2 (mean 85.2) | 24 weeks–3.7 years (mean 1.57 years) | 5 (25%) residual bony defects |
| Sahoo et al. 2010 | Split calvarial graft | 11 | Not stated | 18–24 months | No failures |
| Titanium mesh | 6 | 1 (17%) removed (infection) | |||
| PMMA | 5 | 4 (80%) (3 implant exposures/1 infection) | |||
| Sanus et al. 2008 | Cortoss | 20 | 135.9 cm 2 | 18–36 months (mean 24.3 months) | No failures |
| Saringer et al. 2002 | CFRP | 29 | Not stated | 1 month–6.8 years (mean 3.3 years) | No failures |
| Staffa et al. 2007 | Custom-made HA prosthesis | 25 | 13.5–210 cm 2 (mean 120) | 12–79 months (mean 27 months) | No failures |
| Taggard and Menezes 2001 | Split rib | 13 | 8–144 cm 2 (mean 49.4) | 2–48 months (mean 27 months) | No failures |
| Vahtsevanos et al. 2007 | Titanium | 42 | Not stated | 0–129 months (mean 30) | 2 (5%) removed (infection) |
| PMMA | 5 | No failures | |||
| Vanaclocha et al. 1997 | Allogeneic frozen calvarial bone | 20 | 65–150 cm 2 (mean 83.3) | 10–58 months (mean 41 months) | No failures; partial resorption 10% |
| Vanaclocha et al. 1997 | Autogenous autoclaved bone immediate cranioplasty | 62 | Not stated | 10–58 months (mean 41 months) | No failures; partial resorption 19.3% |
| Viterbo et al. 1995 | Split calvarial graft | 11 | 2 × 1 cm to 6 × 35 cm | Not stated | 2 (19%) required second operation |
| Split rib | 2 | No failures | |||
| Conchal cartilage | 1 | No failures | |||
| Wiltfang et al. 2004 | Split calvarium + HA cement | 41 | 54–148 cm 2 | 6–38 months | No failures |
| Zins et al. 2007 | HA cement + titanium/resorbable mesh | 16 | >25 cm 2 | 1–6 years (mean 3 years) | 8 (50%) removed (fragmentation) |
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