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.

A novel bone registration method using impression molding and structured-light 3D scanning technology.

Accurate bone registration is critical for computer navigation and robotic surgery. Existing registration systems are expensive, cumbersome, limited in accuracy and/or require intraoperative radiation. We recently reported a novel method of registration utilizing an inexpensive, compact, and X-ray-free structured-light 3D scanner. However, this technique is not always practical in a real surgical setting where soft tissue and blood can obstruct the continuous line-of-sight required for structured-light technology. We sought to remedy these limitations using a novel technique using rapid-setting impression molding to capture bone surface features and scan the undersurface of the mold with a structured-light scanner. The photonegative of this mold is compared to the preoperative computed tomography (CT)-scan to register the bone. A registration accuracy study was conducted on 36 CT-scanned femur sawbones, simulating typical exposure in hip/knee arthroplasty and bone tumor surgery. A cadaver experiment was also conducted to evaluate the feasibility of using the impression molding in a more realistic operating room setting. The registration accuracy of the proposed technique was 0.50 ± 0.19 mm. This was close to the reported accuracy of 0.43 ± 0.18 mm using a structured-light scanner without impression molding (p = 0.085). In comparison, historical values for "paired-point" and intraoperative CT image-based registration methods currently used in modern robotic/computer-navigation systems were 0.68 ± 0.14 mm (p = 0.004) and 0.86 ± 0.38 mm, respectively. The registration accuracy of the cadaver experiment was consistent with that of sawbone experiments. Although future studies are needed to extend to human subjects, this study shows that the impression molding method can produce comparable or better registration accuracy than the existing techniques.

Report on a novel bone registration method: A rapid, accurate, and radiation-free technique for computer- and robotic-assisted orthopedic surgeries.

INTRODUCTION: Computer- and robotic-assisted technologies have recently been introduced into orthopedic surgery to improve accuracy. Each requires intraoperative "bone registration," but existing methods are time consuming, often inaccurate, and/or require bulky and costly equipment that produces substantial radiation. METHODS: We developed a novel method of bone registration using a compact 3D structured light surface scanner that can scan thousands of points simultaneously without any ionizing radiation.Visible light is projected in a specific pattern onto a 3 × 3 cm2 area of exposed bone, which deforms the pattern in a way determined by the local bone geometry. A quantitative analysis reconstructs this local geometry and compares it to the preoperative imaging, thereby effecting rapid bone registration.A registration accuracy study using our novel method was conducted on 24 CT-scanned femur Sawbones®. We simulated exposures typically seen during knee/hip arthroplasty and common bone tumor resections. The registration accuracy of our technique was quantified by measuring the discrepancy of known points (i.e., pre-drilled holes) on the bone. RESULTS: Our technique demonstrated a registration accuracy of 0.44 ± 0.22 mm. This compared favorably with literature-reported values of 0.68 ± 0.14 mm (p-value = 0.001) for the paired-point technique13 and 0.86 ± 0.38 mm for the intraoperative CT based techniques 14 (not enough reported data to calculate p-value). CONCLUSION: We have developed a novel method of bone registration for computer and robotic-assisted surgery using 3D surface scanning technology that is rapid, compact, and radiation-free. We have demonstrated increased accuracy compared to existing methods (using historical controls).