Page 37 - Clinical relevance of current materials for cranial implants

Autologous bone is inferior to alloplastic cranioplasties
RESULTS
Characteristics of included studies 2 The literature search yielded a total of 5683 eligible papers, of which 228 were
eventually included in this systematic review (Supplementary Table 2).
Of the 228 included studies, 212 (93.0%) had a retrospective design. Two hundred one were case series, 20 case reports, 5 cohort studies, and 2 randomized clinical trials. Studies were published between 1952 and January 2017 and were conducted on 6 continents, whereas most of them (216; 94.7%) originated from North America, Europe, or Asia.
Many studies were flawed in their reporting of outcomes; even basic information, such as patient age, sex, or indication for cranioplasty, was not reported in all cases. Only 4.8% of the studies reported on smoking behavior of their patients, whereas 82.5% of studies described the patient’s sex (Table 1).
Included studies were quite heterogeneous due to a large variability in surgical procedure, outcome definitions, and patient details. Therefore, no meta-analysis could be performed.
Study sizes ranged from 1 to 67219 cranioplasties, totaling 10,346 cranioplasties. In 193 studies a single material was used for cranioplasty, whereas in 35 two or more materials were used (Table 2). Autologous bone was the most frequently used material for cranioplasty (n=3335 cranioplasties), whereas PEEK was infrequently used (n=250 cranioplasties). In 112 (60.2%) studies the mean follow-up was longer than 1 year. Complications of cranioplasties were reported in 220 studies. Overall, reported complications ranged from wrinkle formation20 and vomiting21 to death22, without a clear threshold as to the definition of a complication.
Neurological function assessment after cranioplasty was reported in 44 studies, of which 22 used a numerical scale. The Glasgow Outcome Scale (GOS) was reported in 98,12,23-29, The Glasgow Coma Scale (GCS) in 17 occurrences23-27,30-41, and 1 study used the House-Brackmann scale42.
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