A quantitative accuracy assessment of the use of a rigid robotic arm in navigated placement of 726 pedicle screws.

BACKGROUND: Traditional minimally invasive fluoroscopy-based techniques for pedicle screw placement utilize guidance, which may require fluoroscopic shots. Computerized tomography (CT) navigation results in more accurate screw placement. Robotic surgery seeks to establish access and trajectory with greater accuracy. OBJECTIVE: This study evaluated the screw placement accuracy of a robotic platform. METHODS: Demographic data, preoperative/postoperative CT scans, and complication rates of 127 patients who underwent lumbosacral pedicle screw placement with minimally invasive navigated robotic guidance using preoperative CT were analyzed. RESULTS: On the GRS scale, 97.9% (711/726) of screws were graded A or B, 1.7% (12/726) of screws graded C, 0.4% (3/726) of screws graded D, and 0% graded E. Average offset from preoperative plan to final screw placement was 1.9 ± 1.5 mm from tip, 2.2 ± 1.4 mm from tail and 2.9 ± 2.3° of angulation. CONCLUSIONS: Robotic-assisted surgery utilizing preoperative CT workflow with intraoperative fluoroscopy-based registration improves pedicle screw placement accuracy within a patient's pedicles.

Navigated robotic assistance results in improved screw accuracy and positive clinical outcomes: an evaluation of the first 54 cases.

Computer-aided navigation and robotic guidance systems have become widespread in their utilization for spine surgery. A recent innovation combines these two advances, which theoretically provides accuracy in spinal screw placement. This study describes the cortical and pedicle screw accuracy for the first 54 cases where navigated robotic assistance was used in a surgical setting. This is a retrospective chart review of the initial 54 patients undergoing spine surgery with pedicle and cortical screws using robotic guidance with navigation. A computed tomography (CT)-based Gertzbein and Robbins System (GRS) was used to classify pedicle screw accuracy. Screw tip, tail, and angulation offsets were measured using image overlay analysis. Screw malposition, reposition, and return to operating room rates were collected. 1 of the first 54 cases was a revision surgery and was excluded from the study. Ten screws were placed without the robot due to surgeon discretion and were excluded for the data analysis of 292 screws. Only 0.68% (2/292) of the robot-assisted screws was repositioned based on surgeon discretion. Based on the GRS CT-based grading, 98.3% (287/292) were graded A or B, 1.0% (3/292) screws were graded C, and only 0.7% (2/292) screws was graded D. The average offset from preoperative plan to actual final placement was 1.9 mm from the tip, 2.3 mm from the tail, and 2.8° of angulation. In the first 53 cases, 292 screws placed with navigated robotic assistance resulted in a high level of accuracy (98.3%), adequate screw offsets from planned trajectory, and zero complications.

Surgical Outcomes and Their Correlation with Increasing Surgical Experience in a Series of 250 Ruptured or Unruptured Aneurysms Undergoing Microsurgical Clipping.

BACKGROUND: The development of endovascular techniques has offered extraordinary therapeutic opportunities to treat intracranial aneurysms. However, mainly for anterior circulation aneurysms, no clear superiority of these techniques compared with microsurgical clipping has been shown in terms of morbidity, mortality, aneurysm occlusion rate, and long-term protection from recanalization and rebleeding. We reviewed the data from a retrospective case series to determine the clinical and radiological outcomes of clipped ruptured and unruptured aneurysm to analyze the relationship between increasing surgical experience and operative time, recovery time, and clinical outcomes. METHODS: A total of 250 consecutive aneurysms in 221 patients had been treated from June 2009 to June 2015. The postoperative complications, recovery time (only for the unruptured group), operative time, clinical outcomes, and aneurysm occlusion rate at 3 months were analyzed for both ruptured and unruptured aneurysms. Linear regression was used to analyze the relationship between surgical experience and the operative time, recovery time, and clinical outcomes. RESULTS: The complication rate was very low in the unruptured cases (117 patients), with 100% of patients in good clinical status at 3 months. In the ruptured cases (104 patients), the presenting neurological status significantly influenced the postoperative outcomes. Complete obliteration found on the 3-month digital subtraction angiogram was obtained for 96.6% of the treated aneurysms in both groups. A significant correlation was found between surgical experience and both the operative time and recovery time. CONCLUSIONS: In a subset of patients (aneurysm located in the anterior circulation and <12 mm), microsurgical clipping appeared to be as safe as endovascular treatment and can obtain a very high complete occlusion rate. Increasing surgical experience improved the operative time and recovery time, with a trend toward improvement of the clinical outcomes.

Focal hole versus screw stimulation to prevent false negative results in detecting pedicle breaches during spinal instrumentation.

OBJECTIVE: We describe a stimulus-evoked EMG approach to minimize false negative results in detecting pedicle breaches during lumbosacral spinal instrumentation. METHODS: In 36 patients receiving 176 lumbosacral pedicle screws, EMG threshold to nerve root activation was determined using a focal probe inserted into the pilot hole at a depth, customized to the individual patients, suitable to position the stimulating tip at the point closest to the tested nerve root. Threshold to screw stimulation was also determined. RESULTS: Mean EMG thresholds in 161 correctly fashioned pedicle instrumentations were 7.5 mA ±â€¯2.46 after focal hole stimulation and 21.8 mA ±â€¯6.8 after screw stimulation. Direct comparison between both thresholds in individual pedicles showed that screw stimulation was always biased by an unpredictable leakage of the stimulating current ranging from 10 to 90%. False negative results were never observed with hole stimulation but this was not true with screw stimulation. CONCLUSIONS: Focal hole stimulation, unlike screw stimulation, approaches absolute EMG threshold as shown by the lower normal limit (2.6 mA; p < 0.05) that borders the upper limit of threshold to direct activation of the exposed root. SIGNIFICANCE: The technique provides an early warning of a possible pedicle breakthrough before insertion of the more harmful, larger and threaded screw.

Non-invasive high voltage electrical stimulation as a monitoring tool of nerve root function in lumbosacral surgery.

OBJECTIVE: To verify the safety and clinical use of non-invasive high-voltage electrical stimulation (HVES) in patients with compressive radiculopathy. To test the feasibility of HVES to survey nerve root function during lumbosacral surgery. METHODS: In 20 patients undergoing lumbosacral surgery for degenerative spinal diseases, compound muscle action potentials (CMAPs) evoked by maximal HVES were bilaterally recorded throughout surgery from L3 to S2 radicular territories. A preliminary study was performed in awake patients to rule out detrimental effects caused by HVES. RESULTS: Preoperative study confirmed the safety of HVES. Unexpectedly, a transient but significant remission of pain was observed after root stimulation. Intraoperative monitoring (IOM) was accomplished in all patients. HVES never hindered surgical procedures and never caused mechanical damage within the operatory field. In 4 patients acute, highly focal and reversible conduction failure was promptly detected by HVES in radicular territories congruent with the root manipulated at that moment. CONCLUSIONS: HVES is a safe and sensitive tool to monitor nerve root function in lumbosacral surgery. SIGNIFICANCE: The method is based on the assumption that any acute conduction failure occurring during surgery can be immediately and unambiguously detected by HVES if root stimulation is supramaximal and delivered rostral to the surgical level.