Swiss Prospective Autologous Bone Flap Resorption Study

Study Overview
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Brief Summary
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The complications after reimplantation of cryoconserved autologous bone flaps are reported inhomogeniously in the literature. Especially the incidence of bone flap resorption varies from 0% to about 30%. More recent retrospective studies seem to find higher resorption rates and thus suggest to implant artificial bone replacements from the start. The Swiss Prospective Autologous bone Resorption Study is the first propspective observational study designed to determine the true incidence of autologous bone resorption.

Detailed Description
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Patients undergoing decompressive craniectomy and delayed reimplantation of the cryoconserved autologous bone flap are included in a clinical and image-based follow-up to identify cases and severity of bone flap resorption. The explanted autologous bone flaps are cryoconserved and reimplanted at a time-point defined by the surgeon according to standards of the participating hospital. The fixation of the bone flap is also performed according to the surgeon's decision. A cranial CT is performed within one week after reimplantation to define a baseline. A second, only clinical, follow-up will take place within 2 months after reimplantation. Two more follow-ups including photodocumentation of the cranial and facial symmetry (portrait and profile) and cranial CT will take place 12 and 24 months after reimplantation. The indication for surgical revision in case of bone flap resorption is independent from the study and falls under the responsibility of the treating surgeon.

Official Title
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Swiss Prospective Autologous Bone Flap Resorption Study

Conditions
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Brain Edema

Intervention / Treatment
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* Procedure: Reimplantation of cryoconserved bone flap


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: all patients after hemicraniectomy or bifrontal craniectomy age 18-99 y/o ability to understand and sign informed consent (alternatively, legal representative may sign) Exclusion Criteria: bone flap not fit for reimplantation no cryoconservation performed but other technique pregnancy patient's death

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 99 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Reimplantation of cryoconserved bone flap<br>All patients who receive reimplantation of a cryoconserved autologous bone flap | Procedure: Reimplantation of cryoconserved bone flap<br>* A bone flap, which was explanted for decompression of a swollen brain or following severe head trauma and which was cryoconserved in the meantime is reimplanted. This procedure is the gold-standard therapy after decompressive hemicraniectomy and is routinely performed.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Incidence of a relevant bone resorption within 12 months after reimplantation | The extent of bone flap resorption is analyzed as well objectivela as subjectivels: objective criteria: Volumetric reconstruction of the bone flap from the CT scans and subtration of the actual bone flap volume from the 3D model at the basline-timepoint directly after reimplantation subjective: a bone flap resorption score is validated | 12 months | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Incidence of an indication for surgical revision | The indication for a surgical revision falls under responsibility of the treating surgeon. | 12 and 24 months after reimplantation | 
| Death | death | 2, 12 and 24 months after reimplantation | 
| Infections | Infections | 2, 12 and 24 months after reimplantation | 
| Fluid collections and bleedings | subgaleal, epidural and subdural fluid collections and hematomas | 2, 12 and 24 months after reimplantation | 
| Hydrocephalus | hydrocephalus | 2, 12 and 24 months after reimplantation | 
| Temporal muscle atrophy | temporal muscle atrophy | 2, 12 and 24 months after reimplantation | 
| timepoint between explantation and reimplantation | measured in months | 2, 12 and 24 months after reimplantation | 
| patient age | in years | 2, 12 and 24 months after reimplantation | 
| fragmentation of the bone flap | in number of pieces | 2, 12 and 24 months after reimplantation | 
| temperature used for cryoconservation | in °C | 2, 12 and 24 months after reimplantation | 
| pathologies leading to explantation of the bone flap (hemicraniectomy) | trauma, tumor, stroke and others | 2, 12 and 24 months after reimplantation | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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autologous bone flap, decompressive craniectomy, malignant brain swelling, patient specific implant, bone resorption, aseptic bone necrosis