Classification of bone flap resorption after cranioplasty: a proposal for a computed tomography-based scoring system

Abstract

Background Bone flap resorption (BFR) is the most prevalent complication resulting in autologous cranioplasty failure, but no consensus on the definition of BFR or between the radiological signs and relevance of BFR has been established. We set out to develop an easy-to-use scoring system intended to standardize the interpretation of radiological BFR findings. Methods All 45 autologous cranioplasty patients operated on at Oulu University Hospital from 2004 to 2014 were identified, and the bone flap status of all the available patients was evaluated using the new scoring system. Derived from previous literature, a three-variable score for the detection of BFR changes is proposed. The variables “Extent” (estimated remaining bone volume), “Severity” (possible perforations and their measured diameter), and “Focus” (the number of BFR foci within the flap) are scored from 0 to 3 individually. Using the sum of these scores, a score of 0–9 is assigned to describe the degree of BFR. Additionally, independent neurosurgeons assessed the presence and relevance of BFR from the same data set. These assessments were compared to the BFR scores in order to find a score limit for relevant BFR. Results BFR was considered relevant by the neurosurgeons in 11 (26.8%) cases. The agreement on the relevance of BFR demonstrated substantial strength ( κ 0.64, 95%CI 0.36 to 0.91). The minimum resorption score in cases of relevant BFR was 5. Thus, BFR with a resorption score ≥ 5 was defined relevant (grades II and III). With this definition, grade II or III BFR was found in 15 (36.6%) of our patients. No risk factors were found to predict relevant BFR. Conclusions The score was proven to be easy to use and we recommend that only cases with grades II and III BFR undergo neurosurgical consultation. However, general applicability can only be claimed after validation in independent cohorts.

Safety, Feasibility, and Patient-Rated Outcome of Sonolucent Cranioplasty in Extracranial-Intracranial Bypass Surgery to Allow for Transcranioplasty Ultrasound Assessment

“…Additionally, alloplastic cranial implants provide ideal cosmetic outcomes by circumventing resorption complications commonly associated with autologous bone flap replacement. 13 , 23 , 24 , 25 However, while there is clear potential benefit to TCUS, widespread use of the technique has yet to be achieved, commensurate with the novelty of its application.…”

A Comparison between Pediatric and Adult Patients after Cranioplasty: Aseptic Bone Resorption Causes Earlier Revision in Children

“…This value is in the lower range of the described rates. 9,22,23 The supplementary table additionally compares our ABR data with other publications in which the ABR collective was described in detail (►Table S1, available in online version).…”

Favourable long-term recovery after decompressive craniectomy: the Northern Finland experience with a predominantly adolescent patient cohort

“…Data on patient characteristics, operative technique, timing, reoperations and complications were collected from the patient records. Radiological bone flap resorption after autologous cranioplasty was evaluated using the Oulu resorption score [ 12 ].…”