A personalized 3D printed cranial shield using mirror-image modeling: design and clinical assessment.

Background: Patients who undergo decompressive craniectomy (DC) are at increased risk of head trauma due to postoperative cranial defects, which not only raise concerns about physical vulnerability but also negatively impact psychological well-being. Conventional protective strategies remain insufficient. This study aimed to develop a personalized, low-cost, three-dimensional (3D) printed external head protection device using mirror-image modeling, and to evaluate its performance in providing physical protection and improving patient-reported outcomes during the post-discharge period.

Method: A prospective study was conducted involving 58 patients treated with DC between August 2023 and February 2025 across two neurosurgical centers. Participants were randomly assigned to an observation group (n = 28), who wore a custom-designed 3D printed protective device based on postoperative CT scans, or to a control group (n = 30) without special protective measures. A custom questionnaire was used to assess satisfaction with appearance, willingness to engage in social activities, and fear of accidental impact at weeks 1, 4, and 8 post-discharge. Objective indicators such as fall events, adverse reactions, and device integrity were also recorded.

Results: The 3D printed models demonstrated good anatomical fit and structural reliability. At weeks 4 and 8, the observation group showed significantly higher Visual Analog Scale (VAS) scores compared to the control group (P = 0.014 and P = 0.002, respectively), with continuous improvement over time (P < 0.05). The average daily usage time of the device was 4.4 ± 1.2 h. No cases of skin irritation or pressure injuries were reported. One patient in the observation group experienced a fall that caused a minor device crack but no head injury (fall rate: 3.6%). In the control group, two patients fell without head trauma (fall rate: 6.7%).

Conclusions: Our findings introduce a personalized, 3D printed external helmet as a new option for cranial protection after decompressive craniectomy. The prototype provided reliable mechanical shielding, conformed closely to each patient's skull contour, and was well tolerated. By reducing physical risk, boosting confidence in appearance, and alleviating anxiety during the interval before cranioplasty, the device may bridge a critical safety and psycho-social gap in early rehabilitation.