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Utility of Intraoperative Neuromonitoring during Minimally Invasive Fusion of the Sacroiliac Joint.

Woods M, Birkholz D, MacBarb R, Capobianco R, Woods A - Adv Orthop (2014)

Bottom Line: Objective.Baseline patient demographics and medical history, intraoperative electromyography thresholds, and perioperative adverse events were collected after obtaining IRB approval.Conclusions.

View Article: PubMed Central - PubMed

Affiliation: Missoula Bone and Joint, 2360 Mullan Road, Suite C, Missoula, MT 59808, USA.

ABSTRACT
Study Design. Retrospective case series. Objective. To document the clinical utility of intraoperative neuromonitoring during minimally invasive surgical sacroiliac joint fusion for patients diagnosed with sacroiliac joint dysfunction (as a direct result of sacroiliac joint disruptions or degenerative sacroiliitis) and determine stimulated electromyography thresholds reflective of favorable implant position. Summary of Background Data. Intraoperative neuromonitoring is a well-accepted adjunct to minimally invasive pedicle screw placement. The utility of intraoperative neuromonitoring during minimally invasive surgical sacroiliac joint fusion using a series of triangular, titanium porous plasma coated implants has not been evaluated. Methods. A medical chart review of consecutive patients treated with minimally invasive surgical sacroiliac joint fusion was undertaken at a single center. Baseline patient demographics and medical history, intraoperative electromyography thresholds, and perioperative adverse events were collected after obtaining IRB approval. Results. 111 implants were placed in 37 patients. Sensitivity of EMG was 80% and specificity was 97%. Intraoperative neuromonitoring potentially avoided neurologic sequelae as a result of improper positioning in 7% of implants. Conclusions. The results of this study suggest that intraoperative neuromonitoring may be a useful adjunct to minimally invasive surgical sacroiliac joint fusion in avoiding nerve injury during implant placement.

No MeSH data available.


Related in: MedlinePlus

Lateral (a), inlet (b), and outlet (c) views of final implant placement through the ilium, across the sacroiliac joint, and into the sacrum, representing safe implant placement as measured via continuous passive EMG monitoring and fluoroscopy.
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Related In: Results  -  Collection


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fig4: Lateral (a), inlet (b), and outlet (c) views of final implant placement through the ilium, across the sacroiliac joint, and into the sacrum, representing safe implant placement as measured via continuous passive EMG monitoring and fluoroscopy.

Mentions: Prior to surgery, a computed tomography (CT) scan was obtained to determine the presence of anomalous sacral anatomy. MIS SI joint fusion surgery using a series of triangular, titanium porous plasma (TPS) coated titanium implants was performed with the patient on a radiolucent table to facilitate the use of intraoperative fluoroscopy. After general endotracheal anesthesia was administered, the patient was connected via subdermal needle electrodes to a standard neuromonitoring system (NIM-ECLIPSE, Medtronic, Memphis, TN). Continuous free-running EMG monitoring of selected muscle groups innervated by nerves at risk was employed throughout the surgery (IOM procedure description below). The patient was then carefully positioned prone, padded appropriately, and prepped in the normal sterile fashion. A lateral incision (3 cm) was made parallel to the sacral body as viewed on a lateral fluoroscopic image. The gluteal fascia was then incised in line with the incision and the gluteal musculature was bluntly dissected to reach the outer table of the ilium. A 3.2 mm guide pin was passed through the ilium, across the SI joint, and into the sacrum lateral to the neural foramen using an insulated soft tissue retractor. The pin was intermittently stimulated at 8 milliamperes (mA) during advancement to ensure that no neurologic structures were encountered. After the first pin was in an acceptable position, two additional pins were sequentially placed caudally in a triangular pattern to reflect the anatomy of the joint and ensure optimal bony purchase (Figure 2). Pin length was measured to determine implant length. A larger soft tissue protector was then passed over the first pin and a center channel was drilled from the ilium, across the SI joint, and into the sacrum. Drill progression was monitored under fluoroscopy to prevent medial migration of the pin. A cannulated broach was used to prepare a triangular channel and the implant was then delivered into its final position. The guide pin was then removed. A standard ball-tip probe was passed through the center channel of the implant and was progressively stimulated up to a maximum of 20 mA. The implant was considered to be in a safe position if no distal muscle activity was detected at or below 16 mA. If activity was detected, a “search” technique was used, where the probe was set to a constant current of 8 mA and slowly advanced out of the distal end of the implant under fluoroscopic guidance in an effort to identify the location of the adjacent neurologic structure (Figure 3). Based on this information, the implant position was modified if necessary, typically by retracting its position a few millimeters laterally. If the implant was adjusted, stimulation was repeated (as previously described) to ensure proper positioning. This technique was repeated for the remaining 2 guide pins; all 37 patients received 3 implants (Figure 4). Following placement of all implants, the wound was irrigated, final hemostasis was achieved, tissue layers were closed, and local anesthetic was injected. A postoperative CT scan to evaluate final implant position was obtained if clinically indicated but was not performed routinely to avoid excessive patient radiation exposure.


Utility of Intraoperative Neuromonitoring during Minimally Invasive Fusion of the Sacroiliac Joint.

Woods M, Birkholz D, MacBarb R, Capobianco R, Woods A - Adv Orthop (2014)

Lateral (a), inlet (b), and outlet (c) views of final implant placement through the ilium, across the sacroiliac joint, and into the sacrum, representing safe implant placement as measured via continuous passive EMG monitoring and fluoroscopy.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4273583&req=5

fig4: Lateral (a), inlet (b), and outlet (c) views of final implant placement through the ilium, across the sacroiliac joint, and into the sacrum, representing safe implant placement as measured via continuous passive EMG monitoring and fluoroscopy.
Mentions: Prior to surgery, a computed tomography (CT) scan was obtained to determine the presence of anomalous sacral anatomy. MIS SI joint fusion surgery using a series of triangular, titanium porous plasma (TPS) coated titanium implants was performed with the patient on a radiolucent table to facilitate the use of intraoperative fluoroscopy. After general endotracheal anesthesia was administered, the patient was connected via subdermal needle electrodes to a standard neuromonitoring system (NIM-ECLIPSE, Medtronic, Memphis, TN). Continuous free-running EMG monitoring of selected muscle groups innervated by nerves at risk was employed throughout the surgery (IOM procedure description below). The patient was then carefully positioned prone, padded appropriately, and prepped in the normal sterile fashion. A lateral incision (3 cm) was made parallel to the sacral body as viewed on a lateral fluoroscopic image. The gluteal fascia was then incised in line with the incision and the gluteal musculature was bluntly dissected to reach the outer table of the ilium. A 3.2 mm guide pin was passed through the ilium, across the SI joint, and into the sacrum lateral to the neural foramen using an insulated soft tissue retractor. The pin was intermittently stimulated at 8 milliamperes (mA) during advancement to ensure that no neurologic structures were encountered. After the first pin was in an acceptable position, two additional pins were sequentially placed caudally in a triangular pattern to reflect the anatomy of the joint and ensure optimal bony purchase (Figure 2). Pin length was measured to determine implant length. A larger soft tissue protector was then passed over the first pin and a center channel was drilled from the ilium, across the SI joint, and into the sacrum. Drill progression was monitored under fluoroscopy to prevent medial migration of the pin. A cannulated broach was used to prepare a triangular channel and the implant was then delivered into its final position. The guide pin was then removed. A standard ball-tip probe was passed through the center channel of the implant and was progressively stimulated up to a maximum of 20 mA. The implant was considered to be in a safe position if no distal muscle activity was detected at or below 16 mA. If activity was detected, a “search” technique was used, where the probe was set to a constant current of 8 mA and slowly advanced out of the distal end of the implant under fluoroscopic guidance in an effort to identify the location of the adjacent neurologic structure (Figure 3). Based on this information, the implant position was modified if necessary, typically by retracting its position a few millimeters laterally. If the implant was adjusted, stimulation was repeated (as previously described) to ensure proper positioning. This technique was repeated for the remaining 2 guide pins; all 37 patients received 3 implants (Figure 4). Following placement of all implants, the wound was irrigated, final hemostasis was achieved, tissue layers were closed, and local anesthetic was injected. A postoperative CT scan to evaluate final implant position was obtained if clinically indicated but was not performed routinely to avoid excessive patient radiation exposure.

Bottom Line: Objective.Baseline patient demographics and medical history, intraoperative electromyography thresholds, and perioperative adverse events were collected after obtaining IRB approval.Conclusions.

View Article: PubMed Central - PubMed

Affiliation: Missoula Bone and Joint, 2360 Mullan Road, Suite C, Missoula, MT 59808, USA.

ABSTRACT
Study Design. Retrospective case series. Objective. To document the clinical utility of intraoperative neuromonitoring during minimally invasive surgical sacroiliac joint fusion for patients diagnosed with sacroiliac joint dysfunction (as a direct result of sacroiliac joint disruptions or degenerative sacroiliitis) and determine stimulated electromyography thresholds reflective of favorable implant position. Summary of Background Data. Intraoperative neuromonitoring is a well-accepted adjunct to minimally invasive pedicle screw placement. The utility of intraoperative neuromonitoring during minimally invasive surgical sacroiliac joint fusion using a series of triangular, titanium porous plasma coated implants has not been evaluated. Methods. A medical chart review of consecutive patients treated with minimally invasive surgical sacroiliac joint fusion was undertaken at a single center. Baseline patient demographics and medical history, intraoperative electromyography thresholds, and perioperative adverse events were collected after obtaining IRB approval. Results. 111 implants were placed in 37 patients. Sensitivity of EMG was 80% and specificity was 97%. Intraoperative neuromonitoring potentially avoided neurologic sequelae as a result of improper positioning in 7% of implants. Conclusions. The results of this study suggest that intraoperative neuromonitoring may be a useful adjunct to minimally invasive surgical sacroiliac joint fusion in avoiding nerve injury during implant placement.

No MeSH data available.


Related in: MedlinePlus