Cost Effectiveness in Cranioplasty: Investigational 3D-Printed Method for Patient-Specific Cranial Implant
Jonathan A Forbes, MD
Joseph S. Cheng, MD, MS
Neurological surgeries in the United States account for a substantial portion of national health care costs. Advances in science and technology increasingly help surgeons develop more efficient and cost-effective solutions to address these neurosurgical problems. Finding novel ways to reduce surgical expenditures helps to reduce the financial burden on hospital and patient without compromising quality of care. A common neurosurgical procedure represents one such example, where advances in 3D printing and investigational technology are helping to make production of patient-specific cranial implants more cost-effective.
Cranioplasties are commonly performed weeks to months following a decompressive craniectomy.1 The cranioplasty procedure, performed to restore cosmesis and protect the brain from mechanical stress and unchecked atmospheric pressure, typically utilizes the patient’s own bone flap harvested during the initial procedure. This autologous bone flap is stored in a sterile fashion either via cryopreservation or in a subcutaneous pouch until the patient is cleared for re-implantation. While autologous bone is preferred due its to ease and cost-effectiveness, a number of complications (e.g, infection, flap comminution, bony resorption) can arise, requiring an alternative method of calvarial reconstruction.2 At the University of Cincinnati College of Medicine’s primary teaching hospital neurosurgical providers typically contract through a third-party vendor to request a patient-specific cranial implant (PSCI). Most vendors require a thin-cut, non-contrast CT scan of the head to manufacture a polyetheretherketone (PEEK) PSCI. Clinically this method results in favorable cosmesis and outcomes, but is costly.3 Currently, engineers at our institution are finalizing design of a freeware program that automates construction of a virtual model of the cranial defect after thin-cut CT imaging of the head has been obtained (Figure 1). A negative of this virtual model can subsequently be printed in polycarbonate, sterilized prior to the OR, and used intra-operatively with poly-methyl methacrylate (PMMA) cement to recapitulate a cosmetically-precise, PSCI. Given the pressing need to reduce health care expenditures in the current financial climate,4 we sought to evaluate the financial utility of this investigational strategy.
Figure 1: : (A) and (B) cadaveric specimen following right decompressive craniectomy. (C) Same specimen pictured following cranioplasty with patient-specific cranial implant. PSCI printed/constructed using investigational freeware.
Cost of Third-Party Implant
PEEK PSCIs are a popular method for calvarial reconstruction, when autologous implants are not available. The aesthetics and complication rates are comparable to that of autologous bone.5 The major downside is the costs of implant production and delivery using a third-party vendor. The average cost for the implant has been cited as $12,600.3
Costs of 3D-Printed PSCI
The investigational method for producing a cranial implant utilizes a polycarbonate mold that is 3D-printed outside the operation room, sterilized prior to the procedure, and used intra-operatively with PMMA cement to create a PSCI. A virtual model of the mold is generated using DICOM CT data processed through the investigational freeware program (Figure 1). An entry-level 3D printer, which can reasonably be obtained for under $1500 is used to print the mold using polycarbonate (PC) material.6,7 The polycarbonate mold is sterilized and prepared for the OR. A kilogram of PC filament retails for approximately $20-25 and can produce roughly 7-10 molds.3 Intra-operatively, PMMA bone cement is used with the mold to create the actual PSCI. One preparation of PMMA bone cement that can be used intra-operatively for creation of the PSCI is the Stryker Spineplex Bone Cement (Stryker, CA), although cheaper alternatives can be found. Two units of the bone cement are often required to create the implant; the estimated cost of two units of Stryker Spineplex Bone Cement is $1,250. The required time in the operation room to create the implant from the mold is estimated in our analysis at 20 minutes. While outdated, a 2001 study determined that the average cost of a minute of O.R. time in the U.S. is $62/min.4
Calculating the extra expenses per procedure utilizing this strategy, minus the initial purchase of entry-level 3D printer, yields: PC material ($3) + PMMA ($1,250 x 2) + OR time ($1,240) = approximately $3,750.
Increasingly, hospital reimbursement from CMS for acute-care, inpatient procedures has transitioned to a prospective payment system where ICD-10 and Medicare severity diagnosis-related group (MS-DRG) codes (further modified by factors inherent to the region and hospital) are used to calculate a predetermined payment for a procedure. These types of payments, made using the CMS acute inpatient prospective payment system (IPPS), totaled $118 billion and accounted for approximately 17% of Medicare spending in 2017. Increased utilization of predetermined, fixed payments rewards hospital and provider efficiency.6
Routine cranioplasties without major complication or comorbidity utilize DRG-024.7 CMS payment can be determined by multiplying the relative weight assigned to DRG-024 and the hospital base payment rate. The relative weight for each DRG code is determined by the expected relative costliness of inpatient treatment under the care of a reasonably efficient provider. The predetermined amount is intended to cover the cost of the implant, as well as the cost of all inpatient services, including compensation of the health care team. Thus, savings from implant costs are transferred directly to the hospital system and indirectly to the patient.
The CNS Leadership !nstitute prepares its matriculants to tackle new initiatives on issues affecting neurosurgery, both nationally and internationally. Cost-containment is currently a major issue in the United States, where health care costs accounted for approximately 18% of the GDP in 2018. These considerations have become especially relevant in light of the trend of decreasing hospital reimbursement associated with the current COVID-19 pandemic. In June, the World Bank predicted the global economy would shrink by 5.2% in the ensuing year. This would represent the largest recession since the Second World War.8 Finding novel ways to reduce hospital spending is a major priority for hospital networks, insurance providers, and the federal government.
In this analysis, we reviewed the cost of PSCI for cranioplasty through third party vendors, which had been reasonably estimated at $12,600. We calculated the costs associated with creating a PSCI using investigational freeware, 3D printing of a polycarbonate mold, and intra-operative molding with PMMA at $3,750. This provided an estimated savings of approximately 70%. As both options of third-party vendor manufactured PSCI and investigational 3D printed PMMA implant fall under the umbrella of cranioplasty, the same DRG code would be utilized and the CMS reimbursement would be the same for both procedures. The discount of approximately 70% of the cost of the PSCI would be transferred directly to the hospital system and indirectly to the patient. Cost-effective strategies such as the investigational method discussed in this article are expected to gain increasing importance as the United States continues to push towards value-centric health care. The authors would like to thank the CNS Leadership Institute for providing relevant direction and guidance for this analysis.
- Iaccarino C, Kolias AG, Roumy L-G, Fountas K, Adeleye AO. Cranioplasty Following Decompressive Craniectomy. Front Neurol [Internet]. 2019 Jan 29 [cited 2020 Oct 28];10:1357. Available from: http://www.ncbi.nlm.nih.gov/pubmed/32063880
- Beez T, Munoz-Bendix C, Steiger HJ, Beseoglu K. Decompressive craniectomy for acute ischemic stroke. Vol. 23, Critical Care. BioMed Central Ltd.; 2019.
- Kinsman M, Aljuboori Z, Ball T, Nauta H, Boakye M. Rapid high-fidelity contour shaping of titanium mesh implants for cranioplasty defects using patient-specific molds created with low-cost 3D printing: A case series. Surg Neurol Int [Internet]. 2020 Sep 1 [cited 2020 Oct 29];11. Available from: https://pubmed.ncbi.nlm.nih.gov/33033650/
- Macario A. What does one minute of operating room time cost? [Internet]. Vol. 22, Journal of Clinical Anesthesia. J Clin Anesth; 2010 [cited 2020 Oct 29]. p. 233–6. Available from: https://pubmed.ncbi.nlm.nih.gov/20522350/
- Punchak M, Chung LK, Lagman C, Bui TT, Lazareff J, Rezzadeh K, et al. Outcomes following polyetheretherketone (PEEK) cranioplasty: Systematic review and meta-analysis. Vol. 41, Journal of Clinical Neuroscience. Churchill Livingstone; 2017. p. 30–5.
- Medicare Hospital Prospective Payment System How DRG Rates Are Calculated and Updated Office of Inspector General Office of Evaluation and Inspections Region IX. 2001.
- ICD-10-CM/PCS MS-DRG v37.0 Definitions Manual [Internet]. [cited 2020 Oct 29]. Available from: https://www.cms.gov/icd10m/version37-fullcode-cms/fullcode_cms/P0002.html
- COVID-19 to Plunge Global Economy into Worst Recession since World War II [Internet]. [cited 2020 Oct 30]. Available from: https://www.worldbank.org/en/news/press-release/2020/06/08/covid-19-to-plunge-global-economy-into-worst-recession-since-world-war-ii