Accuracy, efficacy, and clinical applications of the Radionics Operating Arm System

The aim of this study was to evaluate the accuracy and efficacy of the Radionics Operating Arm System (OAS; Radionics Applications Software, Burlington, MA) in a routine clinical setup. The OAS is a frameless stereotactic articulated arm that can be used in conjunction with computed tomography (CT) or magnetic resonance (MR) imaging to provide image-based intraoperative navigation. The system was used in 130 consecutive cases. It failed or was considered unreliable in 4.6% of patients. Among the remaining patients, 103 had OAS-guided craniotomies, 11 had frameless stereotactic biopsies, and 10 had OAS-guided anterior cervical surgery. Patients were imaged 3-12 hours prior to surgery. Skin markers were used in all cases. The OAS accuracy was evaluated by measuring the difference between the actual probe position and its analogous position on the images. Frameless stereotactic biopsies were performed using the OAS, a modified probe, and a twist-drill. Anterior cervical surgery was performed using the OAS, MRI images, and a rigid cervical collar. The duration of the procedure was recorded for the first 50 patients, and the value of the OAS in localizing the site of craniotomy, the margin of the lesion, and the extent of the resection was also recorded. The system was associated with insignificant prolongation of procedure setup and was sufficiently reliable and achieved a useful registration in 124 (95.4%) patients. The mean accuracy of the system, using skin markers, was 2.5 mm. The OAS was also adaptable for performing other tasks, such as an interactive needle biopsy without a frame. Its use in conjunction with a hollow probe, to perform biopsy or aspiration of 11 brain lesions, produced 100% positive results. Its use in conjunction with MRI and a cervical collar fiducial system, to perform anterior cervical surgery in 10 patients, localized the level in all patients. Overall, the Radionics OAS was sufficiently reliable and accurate in a wide range of routine neurosurgical procedures. Therefore, we integrated it into our routine neurosurgical practice.