A novel intraoperative method to project osteotomy lines for accurate resection of primary bone sarcomas.

Background: Accurate reproduction of a preoperative plan is critical in wide resection of bone sarcomas. Recent advances in computer navigation and 3D-custom jigs have increased resection accuracy, although with certain practical drawbacks. Methods: We developed a novel "projector method" that projects the preoperative osteotomy lines onto the bone. A sawbone study was conducted to evaluate accuracy in reproducing preoperative resection plans. An additional cadaver experiment was conducted to evaluate feasibility in a more realistic operating room setting. Results: Based on the results of experiments conducted on sawbones, the proposed light projector method was more accurate at depicting desired osteotomy lines than a traditional manual method, reducing the corner deviation from 2.53 mm to 0.35 mm, angular deviation from 2.10° to 0.31°, and point deviation from 4.66 mm to 0.48 mm (p < 0.001). Results of the cadaver experiment were consistent with those of sawbone experiments. Conclusions: The new projector method can accurately assist surgeons in visualizing the preoperative plan of osteotomy lines accurately in surgery.

A novel method of light projection and modular jigs to improve accuracy in bone sarcoma resection.

We developed a novel method using a combined light-registration/light-projection system along with an off-the-shelf, instant-assembly modular jig construct that could help surgeons improve bone resection accuracy during sarcoma surgery without many of the associated drawbacks of 3D printed custom jigs or computer navigation. In the novel method, the surgeon uses a light projection system to precisely align the assembled modular jig construct on the bone. In a distal femur resection model, 36 sawbones were evenly divided into 3 groups: manual-resection (MR), conventional 3D-printed custom jig resection (3DCJ), and the novel projector/modular jig (PMJ) resection. In addition to sawbones, a single cadaver experiment was also conducted to confirm feasibility of the PMJ method in a realistic operative setting. The PMJ method improved resection accuracy when compared to MR and 3DCJ, respectively: 0.98 mm versus 7.48 mm (p < 0.001) and 3.72 mm (p < 0.001) in mean corner position error; 1.66 mm versus 9.70 mm (p < 0.001) and 4.32 mm (p = 0.060) in mean maximum deviation error; 0.79°-4.78° (p < 0.001) and 1.26° (p > 0.999) in mean depth angle error. The PMJ method reduced the mean front angle error from 1.72° to 1.07° (p = 0.507) when compared to MR but was slightly worse compared to 0.61° (p = 0.013) in 3DCJ. The PMJ method never showed an error greater than 3 mm, while the maximum error of other two control groups were almost 14 mm. Similar accuracy was found with the PMJ method on the cadaver. A novel method using a light projector with modular jigs can achieve high levels of bone resection accuracy, but without many of the associated drawbacks of 3D printed jigs or computer navigation technology.