Computer Based Algorithm for Patient Specific Implants for Cranioplasty in Patients With Skull Defects
Condition: Stroke; Head Trauma
MeSH terms: Craniocerebral Trauma
Study type: Observational

Summary: 
      Patients with skull defects after craniotomy for example tumor resection, head trauma,
      stroke, need a reimplantation of the bone afterwards. For some circumstances, their own bone
      cannot be reimplanted due to infection, tumor infiltration, damage to the bone, or aseptic
      bone necrosis. In these cases a Patient Specific Implant (PSI) needs to be designed to fit
      into the patient's skull defect.

      The design of the PSI is based on the preoperative CT-scan of the patient's head with the
      skull defect, the imaging data set is uploaded and processed with IPlanNet software by
      BrainLab®. With the help of the software, a 3D model of a negative mould of the PSI is
      designed and printed. In the operation room, the PSI is fabricated under sterile conditions
      using the PSI mould. The design of the PSI mould with the help of IPlanNet is demanding and
      takes some few hours depending on the complexity of the case to be designed. In certain cases
      the accuracy of the fabricated PSI mould is not optimal, so that the surgeon intraoperatively
      has to adapt for the inaccuracy to achieve the best cosmetic and functional results at the
      expense of the operation duration, a known risk factor for postoperative wound infection and
      other perioperative complications.

      Therefore, the investigators have developed an automated computer-based algorithm for PSI
      design (CAPSID). With the help of this tool, an accurate PSI and its corresponding mould can
      be calculated and designed based on the preoperative CT scan of the patient within 5-15
      minutes and the corresponding mould can be printed. This step is automated and thus,
      independent of the neurosurgeons experience and skills in 3D processing software. The mould
      can be used for intraoperative fabrication of the implant under sterile conditions in the
      common way as described above. The possible advantages of the clinical establishment of this
      procedure would be a higher accuracy of the PSI compared to the conventional PSI fabrication
      method with better cosmetic results, lower costs and faster availability and production
      leading to shorter waiting time for the patient, and as a consequence of the higher accuracy
      leading to shorter operation time, with a reduction of risk of operative adverse events for
      the patient. Furthermore, the proof of practicability of this new method, could lead to new
      concepts in the field of Computer-based Patient Specific Implants in modern medicine in
      general.
    

Detailed description: 
      Patients with skull defects after craniotomy for example tumor resection, head trauma,
      stroke, need a reimplantation of the bone afterwards. For some circumstances, their own bone
      cannot be reimplanted due to infection, tumor infiltration, damage to the bone, or aseptic
      bone necrosis. In these cases a Patient Specific Implant (PSI) needs to be designed to fit
      into the patient's skull defect. Several materials are currently used such as titanium,
      poly-ether-ether-ketone (PEEK) or poly-methylmethyl-acrylate (PMMA) for PSI fabrication. At
      the moment, PSI are commercially available from different companies (DePuy Synthes®, EOS®,
      Xilloc®). Apart from the high costs of commercially available PSI, it takes usually several
      weeks until the designed and manufactured PSI is delivered to the hospital ready for
      reimplantation.

      On the other hand, a method for software-based PSI design and intraoperative fabrication of
      the PSI under sterile conditions was described by Stieglitz et al. This method is currently
      used in everyday clinics in the department of neurosurgery in Bern. In short summary, the
      design of the PSI is based on the preoperative CT-scan of the patient's head with the skull
      defect, the imaging data set is uploaded and processed with IPlanNet software by BrainLab®.
      With the help of the software, a 3D model of a negative mould of the PSI is designed and
      printed. In the operation room, the PSI is fabricated under sterile conditions using the PSI
      mould. The design of the PSI mould with the help of IPlanNet is demanding and takes some few
      hours depending on the complexity of the case to be designed. In certain cases the accuracy
      of the fabricated PSI mould is not optimal, so that the surgeon intraoperatively has to adapt
      for the inaccuracy to achieve the best cosmetic and functional results at the expense of the
      operation duration, a known risk factor for postoperative wound infection and other
      perioperative complications.

      Therefore, the investigators have developed an automated computer-based algorithm for PSI
      design (CAPSID). With the help of this tool, an accurate PSI and its corresponding mould can
      be calculated and designed based on the preoperative CT scan of the patient within 5-15
      minutes and the corresponding mould can be printed. This step is automated and thus,
      independent of the neurosurgeons experience and skills in 3D processing software. The mould
      can be used for intraoperative fabrication of the implant under sterile conditions in the
      common way as described above. The possible advantages of the clinical establishment of this
      procedure would be a higher accuracy of the PSI compared to the conventional PSI fabrication
      method with better cosmetic results, lower costs and faster availability and production
      leading to shorter waiting time for the patient, and as a consequence of the higher accuracy
      leading to shorter operation time, with a reduction of risk of operative adverse events for
      the patient. Furthermore, the proof of practicability of this new method, could lead to new
      concepts in the field of Computer-based Patient Specific Implants in modern medicine in
      general. A clinical trial is necessary to proof the advantages and practicability of the
      investigators' concept of computer-based algorithm for PSI design (CAPSID) for patients with
      skull defects.
    

Intervention name(s): Patient Specific Implant
Intervention type(s): Other
Intervention description(s): Implantation of Patient Specific Implant
Observational model: Case-Control
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        Patients with skull defects after craniotomy for example tumor resection, head trauma,
        stroke, need a Patient Specific Implant (PSI).
      
Keywords: stroke; head trauma; Patient Specific Implant; skull defect