Percutaneous Screw Placement Research Articles

A novel computer navigation method for accurate percutaneous sacroiliac screw implantation: A technical note and literature review.

The purpose of this study was to assess the accuracy of percutaneous sacroiliac screw (PSS) placement assisted by screw view model of navigation system for treatment of sacroiliac fractures.Data pertaining to 18 consecutive patients with posterior pelvic ring fracture who received sacroiliac screw fixation between January 2015 and July 2018 at the Second Hospital of Jilin University were retrospectively analyzed. Kirschner wires were placed under the guidance of navigation's screw view mode. The position of the screws was evaluated by computed tomography (CT) scan postoperatively. Fracture dislocation of sacroiliac joint was measured in axial, sagittal, and coronal views of 3 dimensional (3D) CT images preoperatively, postoperatively and at the last follow-up visit. The duration of trajectory planning, guide wire implantation time, screw placement time, intraoperative blood loss, and incidence of screw loosening and clinical complications were also assessed.A total of 27 screws were placed unilaterally or bilaterally into segments S1 or S2. Screw placement was rated as excellent for 88.9% of screws (n = 24), good for 7.4% (n = 2), and poor for 3.7% (n = 1). Preoperatively, the average fracture dislocation of sacroiliac joint on axial, sagittal, and coronal views was 14.3 mm, 9.6 mm, and 7.4 mm, respectively, and the corresponding postoperative figures were 5.6 mm, 3.2 mm, 4.1 mm, respectively. The corresponding correction rates were 60.8%, 66.7%, and 44.6%, respectively. The mean duration of trajectory planning was 6.5 min (2.7–8.9 min). Mean screw implantation time was 32 min (range, 20–53 min), and the mean guide wire implantation time was 3.7 min (range, 2.1–5.3 min). No clinical complications such as neurovascular injury, infection or screw loosening were observed on follow-up.The PSS placement under guidance of screw view model of navigation is a convenient, safe and reliable method.

Percutaneous restoration of bone continuity with screws and PMMA cement in an extensive destruction of the pelvis.

We report a case of combined percutaneous screw placement and cementoplasty guided by CT and fluoroscopy in a 66-year-old man with extensive osteolytic destruction of the right iliac bone and sacral wing due to metastasic infiltrative vesical carcinoma. The medical condition was responsible for very limited and painful walking. Two perpendicular screws were inserted into the iliac bone and sacroiliac joint, and bone cement injection was used to anchor the screws and restore the mechanical continuity of the pelvis ring. This minimally invasive procedure allowed for significant and rapid resumption of painless walking.

Accuracy of navigated and conventional iliosacral screw placement in B- and C-type pelvic ring fractures.

The objective of this study is to report the institutions experiences with standardized 2D computer-navigated percutaneous iliosacral screw placement (CNS), as well as the conventional fluoroscopically assisted screw placement method (CF) over a period of 10years. A total of 604 patients with sacral fractures (OTA B and C) were treated at the institution. Cases with both, a preoperative and postoperative CT scan were included for further analysis. With this prerequisite, a total of 136 cases were included. The quality of screw positioning, length of operation and intraoperative radiation exposure were recorded and compared. Moreover, it was analyzed whether the presence of dysmorphic sacra influenced the precision of screw positioning. Two hundred and thirty-two screws were implanted in 136 patients (100 navigated, 36 conventional). The duration of the average procedure was similar in the two groups [49.8min (p = 0.7) conventional group (CF) vs. 48.0min computer-navigated (CNS) group]. With computer navigation, radiation exposure was significantly reduced by almost half [128.3 vs. 65.2s (p = 0.023)]. Screw placement was more accurate in the navigation group (79.03% CF vs. 86.47% CNS). The presence of dysmorphic sacral foramina or an increased alar slope increased the incidence of screw malpositioning. The conventional percutaneous method and a standardized 2D navigated method have similar rates of malpositioning. Dysmorphic upper sacral foramina and increased alar slope were identified as risk factors for screw malpositioning. Radiation exposure rates were reduced by half when using computer navigation. Therefore, computer navigation in iliosacral screw placement is recommended as method of choice.

Minimal invasive surgical technique in midline lumbar inter-body fusion: A technique note

Midline lumbar inter-body fusion (MIDLF) surgery with cortical bone trajectory (CBT) screw insertion is a modern fusion technique for spinal surgery. The difference in entry point of this trajectory from conventional pedicle screw surgery offers the potential benefits of less soft tissue dissection and reduced blood loss, post-operative wound pain, and infection risks. Because this is a newly developed technique first announced by Santoni in 2009, most surgeons perform this surgery in a mini-open fashion and require more intra-operative fluoroscopy and ionizing radiation exposure during screw placement. In this article, we demonstrate a minimally invasive midline lumbar interbody fusion (MIS-MIDLF) technique with percutaneous CBT screw placement. Using a designed cannulated awl, we only need a single dimensional fluoroscopy view from anterior to posterior (AP view) to achieve an accurate trajectory and therefore reduce radiation exposure. We report our first ten consecutive patients with degenerative spondylolithesis who underwent MISS-MIDLF and were followed up for more than 18 months. The procedure required a single wound of about 3 cm in length in one to two level fusion surgery and only three to four shots of fluoroscopy were needed for each screw placement. There were no screws malpositioned in subsequent plain films or computer tomography scans. We demonstrate a case with detailed surgical procedures and provide this technique as an alternative approach for surgeons performing MILDF surgery.

Hallux Valgus

Category: Bunion Introduction/Purpose: Abnormal motion of the first tarsometatarsal (TMT) joint disrupts the anatomic alignment of the metatarsal head, sesamoid complex and proximal first phalanx. This anatomic disruption combined with the deforming forces of the extensor hallucis longus, adductor tendons, and extensor hallucis brevis result in a hallux valgus deformity. First TMT arthrodesis or the Lapidus procedure has been described as treatment for moderate to severe hallux valgus deformities by correcting hypermobility and restoring anatomic alignment of the first ray. The aim of this study was to evaluate the safety of a percutaneous approach to the Lapidus procedure and its relation to anatomic structures. Methods: A percutaneous, modified Lapidus procedure was performed on 19 embalmed cadaveric feet under fluoroscopic guidance. The specimens were then dissected to identify the extensor hallucis longus (EHL), extensor hallucis brevis (EHB), tibialis anterior (TA), median branch of the superficial peroneal nerve (MBSPN), intermediate branch of the superficial peroneal nerve (IBSPN), deep peroneal neurovascular bundle (DPNVB) and saphenous vein (SV). The structures were localized with reference to percutaneous burr and screw placement during the procedure. Results: The tibialis anterior and intermediate branch of the superficial peroneal nerve were a mean of 3.75 millimeters (mm) and 5.08 mm from the closest burr or screw placement. The extensor hallucis longus and extensor hallucis brevis were at greatest risk under the new approach with mean distances of .92 to 4.08 mm to nearby instrumentation. The extensor hallucis longus or extensor hallucis brevis were either directly pierced or <2 mm from instrumentation on 26 occasions. A terminal branch of the saphenous vein was also either pierced or within 2 mm of instrumentation on 4 occasions. The deep peroneal neurovascular bundle and median branch of superficial peroneal nerve were relatively safe, coming within 2 mm of percutaneous burr or screw placement on only 2 occasions each. Conclusion: The minimally invasive percutaneous Lapidus arthrodesis provides a safe alternative to the traditional, open approach for patients with moderate to severe hallux valgus deformities. This may be a beneficial alternative to conventional open Lapidus procedures by minimizing soft tissue dissection. Further clinical studies must be performed to compare deformity correction, fusion rate, and complications with the modified percutaneous Lapidus procedure.

Ankle Fusion Percutaneous Home Run Screw Fixation

Category: Ankle Arthritis Introduction/Purpose: During internal fixation of ankle fusions, besides the standard crossed screw fixation pattern, the use of a percutaneously placed augmenting screw, directed from the posterolateral tibial metaphysis proximally across the ankle into the talar neck (“ankle fusion home run screw”), is a widely used technique. The placement of this screw is technically demanding and multiple attempts under fluoroscopy guidance are frequently needed to achieve a perfect positioning of the implant. Injuries to local neurovascular and tendinous structures might happen. The objective of this cadaver study was to identify the number of attempts necessary for a perfect positioning of the ankle fusion home run screw and the neurovascular and tendinous structures at risk. Methods: Eleven fresh frozen cadaver limbs were used. Guide wires (3.2 mm) from the Stryker (Selzach, Switzerland) 7.0-mm headless cannulated set were percutaneously placed into the distal posterolateral aspect of the leg, under fluoroscopic guidance, with the ankle held in neutral position. Mal positioned pins were not removed and served as guidance for the following pins. The number of guide wires needed to achieve an acceptable positioning of the implant was noted. After a layered dissection from the skin to the tibia, we evaluated neurovascular and tendinous injuries, and measured the shortest distance between the closest guide pin and the soft tissue structures, using a precision digital caliper. Results: The mean number of guide wires needed to achieve and acceptable positioning of the implant was 2.09 (SD 0.83, range 1- 4). The mean distances between the closest guide pin and the soft tissue structures of interest were: Achilles tendon 6.90 mm (SD 3.74 mm); peroneal tendons 9.65 mm (SD 3.99 mm); sural neurovascular bundle 0.97 mm (SD 1.93 mm); posteromedial neurovascular bundle 14.26 mm (SD 4.56 mm). Sural bundle was in contact with the guide pin in 5/11 specimens (45.5%) and transected in 3/11 specimens (27.3%). Conclusion: The placement of percutaneous ankle fusion home run screws is technically demanding and multiple guide pins are needed. Our cadaveric study showed that important tendinous and neurovascular structures are in close proximity with the guide pins and that the sural bundle is injured in approximately 73% of the cases. Caution should be taken during percutaneous placing of screws and an appropriate approach and surgical dissection to bone is advised.

Percutaneous Posterior to Anterior Screw Fixation of the Talar Neck

Category: Trauma Introduction/Purpose: Fractures of the talar neck and body can be fixed with percutaneously placed screws directed from anterior to posterior or posterior to anterior. The latter has been found to be biomechanically and anatomically superior. Percutaneous pin and screw placement poses anatomic risks for posterolateral and posteromedial neurovascular and tendinous structures. The objective of this study was to enumerate the number of trials for proper placement of two parallel screws and to determine the injury rate to neurovascular and tendinous structures. Methods: Eleven fresh frozen cadaver limbs were used. 2.0 mm guide wires from the Stryker (Selzach, Switzerland) 5.0-mm headless cannulated set were percutaneously placed (under fluoroscopic guidance) into the distal posterolateral aspect of the ankle. All surgical procedures were performed by a fellowship-trained foot and ankle surgeon. Malpositioned pins were left intact to allow later assessment of soft tissue injury. The number of guide wires needed to achieve an acceptable positioning of the implant was noted. Acceptable positioning was defined as in line with the talar neck axis in both AP and lateral fluoroscopic views. After a layered dissection from the skin to the tibia, we evaluated neurovascular and tendinous injuries, and measured the shortest distance between the closest guide pin and the soft tissue structures, using a precision digital caliper. Results: The mean number of guide wires needed to achieve acceptable positioning for 2 parallel screws was 2.91 ± 0.70 (range, 2 - 5). The mean distances between the closest guide pin and the soft tissue structures of interest were: Achilles tendon, 0.53 ± 0.94 mm; flexor hallucis longus tendon, 6.62 ± 3.24 mm; peroneal tendons, 7.51 ± 2.92 mm; and posteromedial neurovascular bundle, 11.73 ± 3.48 mm. The sural bundle was injured in all the specimens, with 8/11 (72.7%) in direct contact with the guide pin and 3/11 (17.3%) having been transected. The peroneal tendons were transected in 1/11 (9%) of the specimens. The Achilles tendon was in contact with the guide pin in 6/11 (54.5%) specimens and transected in 2/11 (18.2%) specimens. Conclusion: The placement of posterior to anterior percutaneous screws for talar neck fixation is technically demanding and multiple guide pins are needed. Our cadaveric study showed that important tendinous and neurovascular structures are in close proximity with the guide pins and that the sural bundle was injured in 100% of the cases. We advise performing a formal small posterolateral approach for proper visualization and retraction of structures at risk. Regardless, adequate patient education about the high risk of injury from this procedure is crucial.

Defining A Safe Zone For Percutaneous Screw Fixation Of The Posterior Malleolus

Category: Trauma Introduction/Purpose: Fixation of the posterior malleolar fragment of an ankle fracture confers stability. Not all posterior fragments are displaced, necessitating open reduction. We hypothesised that a safe anatomic corridor is possible for percutaneous screw fixation in some fracture variants. We conducted an anatomic study to determine if percutaneous fixation was possible and safe. This anatomic assessment of significant structures at the posterior ankle, combined with cadaveric dissection following placement of screw tracts shows that percutaneously fixing the posterior malleolus is achievable in medially positioned fragments. Methods: Multiple percutaneous Kirschner wires were passed into a cadaveric ankle specimen at reproducible anatomic points. The wires were passed into typical locations for posterior malleolus fixation. The specimen was dissected and all wires threatening significant structures were removed. A single safe medial passage was identified. The surface anatomy landmarks for the single safe wire was recorded. Multiple (6) cadaveric specimens were further wired via an entry point using only the surface anatomy landmarks previously determined to be safe. These were dissected to confirm the presence of a safe zone for percutaneous wiring of the posterior malleolus. Image intensifier was used to confirm adequate placement of the wire in the posterior malleolus. Results: A safe medial zone for percutaneous fixation of the posterior malleolus was consistent; this was successfully replicated utilising surface anatomy alone. The entry point for safe percutaneous fixation was found to be 1 cm proximal to the tip of the medial malleolus and immediately lateral to the tendo-achilles. Conclusion: A safe passage for percutaneous screw placement for medially located posterior malleolar fragments (Haraguchi I/II) was identified. A safe zone for percutaneous fixation of the posterior malleolus has been newly defined.

Robot-assisted percutaneous screw placement combined with pelvic internal fixator for minimally invasive treatment of unstable pelvic ring fractures.

PurposeThe purpose of this study was to investigate the safety and efficacy of the combination of robot‐assisted percutaneous screw placement and pelvic internal fixator (INFIX) for minimally invasive treatment of unstable anterior and posterior pelvic ring injuries.MethodsFrom September 2016 to June 2017, twenty‐four patients with unstable anterior and posterior pelvic ring injuries were treated with TiRobot‐assisted percutaneous sacroiliac cannulated screw fixation on the posterior pelvic ring combined with robot‐assisted pedicle screw placement in the anterior inferior iliac spine along with INFIX on the anterior pelvic ring. The results of the treatment, including surgery duration, fluoroscopy frequency, total drilling, amount of blood loss, fracture healing time, and postoperative functional outcomes were recorded and compared with another 21 similar patients who underwent conventional manual positioning surgery.ResultsThe TiRobot group incurred significantly shorter duration of surgery; less fluoroscopy frequency, intraoperative bleeding, and total drilling than in the conventional group (P < 0.05). Postoperative radiological follow‐up showed that all screws were in the safe area and no screw penetrated the cortex. All wounds healed by primary intention and no iatrogenic damage to the blood vessels, nerves, and organs occurred. Patients showed good tolerance to INFIX and reported no discomfort. The mean follow‐up duration was 5.4 months; the fractures were all healed, no loss of reduction occurred, and the mean Majeed score at the last follow‐up did not show any difference.ConclusionTiRobot‐assisted percutaneous screw placement combined with INFIX for the anterior and posterior pelvic ring injuries is accurate, safe, less invasive, and shows satisfactory efficacy, suggesting it is a better method for minimally invasive treatment of unstable pelvic ring fractures.

Challenges and reflections in precise placement of percutaneous sacroiliac joint screw placement

Challenges and reflections in precise placement of percutaneous sacroiliac joint screw placement

Radiation exposure to the surgeon during minimally invasive spine procedures is directly estimated by patient dose.

Radiation exposure is a necessary component of minimally invasive spine procedures to augment limited visualization of anatomy. The surgeon's exposure to ionizing radiation is not easily recognizable without a digital dosimeter-something few surgeons have access to. The aim of this study was to identify an easy alternative method that uses the available radiation dose data from the C-arm to accurately predict physician exposure. The senior surgeon wore a digital dosimeter during all minimally invasive spine fusion procedures performed over a 12-month period. Patient demographics, procedure information, and radiation exposure throughout the procedure were recorded. Fifty-five minimally invasive spine fusions utilizing 330 percutaneous screws were included. Average radiation dose was 0.46 Rad/screw to the patient. Average radiation exposure to the surgeon was 1.06 ± 0.71μSv/screw, with a strong positive correlation (r = 0.77) to patient dose. The coefficient of determination (r2) was 0.5928, meaning almost two-thirds of the variability in radiation exposure to the surgeon is explained by radiation exposure to the patient. Intra-operative radiation exposure to the patient, which is easily identifiable as a continuously updated fluoroscopic monitor, is a reliable predictor of radiation exposure to the surgeon during percutaneous screw placement in minimally invasive spinal fusion surgery and therefore can provide an estimate of exposure without the use of a dosimeter. With this, a surgeon can better understand the magnitude of their exposure on a case-by-case basis rather than on a quarterly basis, or more likely, not at all. These slides can be retrieved under Electronic Supplementary Material.

Soft Tissue Structures at Risk With Percutaneous Posterior to Anterior Screw Fixation of the Talar Neck.

Fractures of the talar neck and body can be fixed with percutaneously placed screws directed from anterior to posterior or posterior to anterior. The latter has been found to be biomechanically and anatomically superior. Percutaneous guidewire and screw placement poses anatomic risks for posterolateral and posteromedial neurovascular and tendinous structures. The objective of this study was to determine the injury rate to local neurovascular and tendinous structures using this technique in a cadaveric model. In addition, we aimed to determine the number of attempts at passing the guidewires required to achieve acceptable placement of 2 parallel screws. Eleven fresh frozen cadaver limbs were used. Two 2.0-mm guidewires were placed under fluoroscopic guidance, posterior to anterior centered within the talus. The number of attempts required was recorded. A layered dissection was then performed to identify injury to any local anatomic structure. The shortest distance between the closest guidewire and the soft tissue structures was measured. The mean total number of guidewires passed to obtain optimal placement of 2 parallel screws was 2.9 ± 0.7. Direct contact between the guidewire and the sural nerve was seen in 100% of the specimens, with the nerve impaled by the guidewire in 3 of 11 (27.2%) cases. The peroneal tendons were impaled in 1 of 11 (9%) specimens and the Achilles tendon was in contact with the guidewire in 8 of the 11 (72.7%) specimens, and impaled at its most lateral border with the guidewire in 2 specimens (18.2%). The placement of posterior to anterior percutaneous screws for talar neck fixation is technically demanding, and multiple guidewires are needed. Our cadaveric study showed that important tendinous and neurovascular structures were in proximity with the guidewires and that the sural nerve was injured in 100% of the cases. Given the risk of injury to these structures, we recommend a formal posterolateral incision for proper visualization and retraction of the anatomic structures at risk.

Treatment of Pediatric and Adolescent Pelvic Ring Injuries With Percutaneous Screw Placement.

Pediatric and adolescent pelvic ring injuries are frequently treated without surgery. In patients with unstable injuries to the pelvic ring, surgical stabilization aids in resuscitation, provides pain relief, and allows for mobilization. Percutaneous pelvic screw fixation is commonly performed in adult patients for unstable pelvic ring injuries, but a paucity of literature exists regarding their use in pediatric patients. The purpose of this study is to review the use, outcome, and management of percutaneous posterior pelvic screws in pediatric patients with unstable pelvic ring injuries. A retrospective review of a prospectively collected orthopaedic trauma database was performed over a 7-year period at a regional level-1 trauma center. All patients between the ages of 7 and 17 who sustained an injury to the pelvic ring and were treated with percutaneous fixation of the posterior pelvic ring were identified. We evaluated the frequency of this technique in the described patient population, incidence of nerve injury, infection, loss of fixation, and need for hardware removal. A total of 238 pediatric patients who sustained a pelvic ring injury were initially identified; following application of study criteria, 67 (28.1%) patients were included in the study. Additional anterior ring fixation was performed in 33 (49.2%) patients. There were no iatrogenic nerve injuries, no infections, and surgical blood loss was <50 mL in all cases. Clinical and radiographic follow-up averaged 33 weeks. No loss of reduction was observed. Eight patients (13%) reported persistent low back pain at last follow-up. Elective hardware removal was performed in 3 patients. The majority of pediatric pelvic ring injuries can be treated without surgery. In the setting of instability, percutaneous pelvic screw fixation can be performed safely. A computed tomography scan is used to evaluate the available osseous pathways for screws and intraoperative fluoroscopy is used to safely perform this technique. Screw removal should be discussed in select patients. Level IV.

Percutaneous and open iliac screw safety and accuracy using a tactile technique with adjunctive anteroposterior fluoroscopy

Background ContextAll currently described percutaneous iliac screw placement methods are entirely dependent on fluoroscopy. PurposeThe purpose of this study was to determine the safety and the accuracy of percutaneous and open iliac screw placement using a primarily tactile technique with adjunctive anteroposterior (AP) fluoroscopy. Study Design/ContextAll patients who underwent open and percutaneous iliac screw placement over a 5-year period were identified. Charts were reviewed to assess for any instances of neurologic or vascular injury associated with iliac screw placement. Screw accuracy was judged with postoperative computed tomography (CT) scans. Patient SampleA total of 133 patients were identified who underwent open or percutaneous iliac screw placement. Computed tomography scans were available for 57 patients, and all of these patients were included in the study, with a total of 115 iliac screws. Outcome MeasuresRadiographic measurements were performed, consisting of the distance of the iliac screw to the sciatic notch on postoperative radiographs and CT scans. Computed tomography scans were used to determine iliac screw accuracy. MethodsCharts were reviewed to assess for any neurologic or vascular injuries related to screw placement. The distance of the iliac screw to the sciatic notch was measured and compared on AP radiography and CT scans. Computed tomography scans were assessed for any screw violation of the iliac cortex or the sciatic notch. The accuracy of open iliac screw placement was compared with minimally invasive percutaneous placement. ResultsThere were no neurologic or vascular injuries related to screw placement in the 133 patients. Computed tomography scans were available for 115 iliac screws, with 3 cortical breaches, all by less than 2 mm. All 112 other screws were accurately intraosseous. There was a strong correlation between the iliac screw to the sciatic notch distance when measured by CT scan compared with AP radiography (r=0.9), thus validating the accuracy of AP fluoroscopy in guiding iliac screw placement with respect to the sciatic notch. Iliac screw accuracy was equal with the open and percutaneous insertion techniques. ConclusionsThe described surgical technique represents a safe and reliable surgical option for iliac screw placement. Intraoperative AP fluoroscopy accurately reflects the distance of the iliac screw to the sciatic notch. Percutaneous iliac screws placed with this technique are as accurate as open iliac screws.

Early experience of placing image-guided minimally invasive pedicle screws without K-wires or bone-anchored trackers.

OBJECTIVE Image guidance for spine surgery has been reported to improve the accuracy of pedicle screw placement and reduce revision rates and radiation exposure. Current navigation and robot-assisted techniques for percutaneous screws rely on bone-anchored trackers and Kirchner wires (K-wires). There is a paucity of published data regarding the placement of image-guided percutaneous screws without K-wires. A new skin-adhesive stereotactic patient tracker (SpineMask) eliminates both an invasive bone-anchored tracker and K-wires for pedicle screw placement. This study reports the authors' early experience with the use of SpineMask for "K-wireless" placement of minimally invasive pedicle screws and makes recommendations for its potential applications in lumbar fusion. METHODS Forty-five consecutive patients (involving 204 screws inserted) underwent K-wireless lumbar pedicle screw fixation with SpineMask and intraoperative neuromonitoring. Screws were inserted by percutaneous stab or Wiltse incisions. If required, decompression with or without interbody fusion was performed using mini-open midline incisions. Multimodality intraoperative neuromonitoring assessing motor and sensory responses with triggered electromyography (tEMG) was performed. Computed tomography scans were obtained 2 days postoperatively to assess screw placement and any cortical breaches. A breach was defined as any violation of a pedicle screw involving the cortical bone of the pedicle. RESULTS Fourteen screws (7%) required intraoperative revision. Screws were removed and repositioned due to a tEMG response < 13 mA, tactile feedback, and 3D fluoroscopic assessment. All screws were revised using the SpineMask with the same screw placement technique. The highest proportion of revisions occurred with Wiltse incisions (4/12, 33%) as this caused the greatest degree of SpineMask deformation, followed by a mini midline incision (3/26, 12%). Percutaneous screws via a single stab incision resulted in the fewest revisions (7/166, 4%). Postoperative CT demonstrated 7 pedicle screw breaches (3%; 5 lateral, 1 medial, 1 superior), all with percutaneous stab incisions (7/166, 4%). The radiological accuracy of the SpineMask tracker was 97% (197/204 screws). No patients suffered neural injury or required postoperative screw revision. CONCLUSIONS The noninvasive cutaneous SpineMask tracker with 3D image guidance and tEMG monitoring provided high accuracy (97%) for percutaneous pedicle screw placement via stab incisions without K-wires.

Computer Navigated Percutaneous Sacroiliac Joint Screws Assisted by Caudal Epidural Contrast Injection

This article describes an innovative technique for effective analgesia and enhanced accuracy in placement of percutaneous sacroiliac screws in patients with unstable, posterior pelvic ring injuries. Our approach involves introducing radio-opaque contrast through an indwelling caudal epidural catheter to enhance existing computer navigation systems. This delineates the lumbosacral nerve roots to promote the safe and accurate placement of sacroiliac screws and concurrently provides effective analgesia. We describe the technique and our first cases. It can be used to supplement your current technique in placing sacroiliac joint screws and provide effective analgesia for our patients.

Anatomical and technical factors associated with superior facet joint violation in lumbar fusion.

OBJECTIVE The aim of this study was to evaluate the anatomical and surgical risk factors for screw-related facet joint violation at the superior level in lumbar fusion. METHODS The authors conducted a retrospective review of a consecutive series of posterior lumbar instrumented fusions performed by a single surgeon. Inclusion criteria were primary lumbar fusion of 1 or 2 levels for degenerative disorders. The following variables were analyzed as possible risk factors: surgical technique (percutaneous vs open screw placement), depth of surgical field, degree of anterior slippage of the superior level, pedicle and facet angle, and facet degeneration of the superior level. Postoperative CT scans were evaluated by 2 independent reviewers. Axial, sagittal, and coronal views were reviewed. Pedicle screws were graded as intra-articular if they clearly interposed between the superior and inferior facet joints of the superior level. Multivariate logistic regression analyses were conducted to assess the factors associated with this complication. RESULTS One hundred thirty-one patients were included. Interobserver reliability for facet joint violation assessment was high (κ = 0.789). The incidence of superior facet joint violation was 12.59% per top-level screw (33 of 262 proximal screws). The rate of facet violation was 28.0% in the percutaneous technique group (14 of 50 patients) and 12.3% in the open surgery group (10 of 81 patients) (OR 2.26, 95% CI 1.09-4.21; p = 0.024). In multivariate logistic regression analysis, independent predictors of facet violation were percutaneous screw placement (adjusted OR 3.31, 95% CI 1.42-7.73; p = 0.006), right-side pedicle screw (adjusted OR 3.14, 95% CI 1.29-7.63; p = 0.011), and facet angle > 45° (adjusted OR 10.95, 95% CI 4.64-25.84; p < 0.0001). CONCLUSIONS The incidence of facet joint violation was higher in percutaneous minimally invasive than in open technique for posterior lumbar spine surgery. Also, coronal orientation of the facet joint is a significant risk factor independent of the surgical technique.

Percutaneous screw placement in the lumbar spine with a modified guidance technique based on 3D CT navigation system.

Several guidance techniques have been employed to increase accuracy and reduce surgical time during percutaneous placement of pedicle screws (PS). The purpose of our study was to present a modified technique for percutaneous placement of lumbar PS that reduces surgical time. We reviewed 23 cases of percutaneous PS placement using our technique for minimally invasive lumbar surgeries and 24 control cases where lumbar PS placement was done via common technique using Jamshidi needles (Becton, Dickinson and Company, Franklin Lakes, NJ, USA). An integrated computer-guided navigation system was used in all cases. In the technique modification, a handheld drill with a navigated guide was used to create the path for inserting guidewires through the pedicles and into the vertebral bodies. After drill removal, placement of the guidewires through the pedicles took place. The PS were implanted over the guidewires, through the pedicles and into the vertebral bodies. Intraoperative computed tomography was performed after screw placement to ensure optimal positioning in all cases. There were no intraoperative complications with either technique. PS placement was correct in all cases. The average time for each PS placement was 6.9 minutes for the modified technique and 9.2 minutes for the common technique. There was no significant difference in blood loss. In conclusion, this modified technique is efficient and contributes to reduced operative time.

Planning, guidance, and quality assurance of pelvic screw placement using deformable image registration

Percutaneous pelvic screw placement is challenging due to narrow bone corridors surrounded by vulnerable structures and difficult visual interpretation of complex anatomical shapes in 2D x-ray projection images. To address these challenges, a system for planning, guidance, and quality assurance (QA) is presented, providing functionality analogous to surgical navigation, but based on robust 3D–2D image registration techniques using fluoroscopy images already acquired in routine workflow. Two novel aspects of the system are investigated: automatic planning of pelvic screw trajectories and the ability to account for deformation of surgical devices (K-wire deflection).Atlas-based registration is used to calculate a patient-specific plan of screw trajectories in preoperative CT. 3D–2D registration aligns the patient to CT within the projective geometry of intraoperative fluoroscopy. Deformable known-component registration (dKC-Reg) localizes the surgical device, and the combination of plan and device location is used to provide guidance and QA. A leave-one-out analysis evaluated the accuracy of automatic planning, and a cadaver experiment compared the accuracy of dKC-Reg to rigid approaches (e.g. optical tracking).Surgical plans conformed within the bone cortex by 3–4 mm for the narrowest corridor (superior pubic ramus) and >5 mm for the widest corridor (tear drop). The dKC-Reg algorithm localized the K-wire tip within 1.1 mm and 1.4° and was consistently more accurate than rigid-body tracking (errors up to 9 mm).The system was shown to automatically compute reliable screw trajectories and accurately localize deformed surgical devices (K-wires). Such capability could improve guidance and QA in orthopaedic surgery, where workflow is impeded by manual planning, conventional tool trackers add complexity and cost, rigid tool assumptions are often inaccurate, and qualitative interpretation of complex anatomy from 2D projections is prone to trial-and-error with extended fluoroscopy time.

Percutaneous Sacroiliac Screw Placement: A Prospective Randomized Comparison of Robot-assisted Navigation Procedures with a Conventional Technique.

Background:Sacroiliac (SI) screw fixation is a demanding technique, with a high rate of screw malposition due to the complex pelvic anatomy. TiRobot™ is an orthopedic surgery robot which can be used for SI screw fixation. This study aimed to evaluate the accuracy of robot-assisted placement of SI screws compared with a freehand technique.Methods:Thirty patients requiring posterior pelvic ring stabilization were randomized to receive freehand or robot-assisted SI screw fixation, between January 2016 and June 2016 at Beijing Jishuitan Hospital. Forty-five screws were placed at levels S1 and S2. In both methods, the primary end point screw position was assessed and classified using postoperative computed tomography. Fisher's exact probability test was used to analyze the screws’ positions. Secondary end points, such as duration of trajectory planning, surgical time after reduction of the pelvis, insertion time for guide wire, number of guide wire attempts, and radiation exposure without pelvic reduction, were also assessed.Results:Twenty-three screws were placed in the robot-assisted group and 22 screws in the freehand group; no postoperative complications or revisions were reported. The excellent and good rate of screw placement was 100% in the robot-assisted group and 95% in the freehand group. The P value (0.009) showed the same superiority in screw distribution. The fluoroscopy time after pelvic reduction in the robot-assisted group was significantly shorter than that in the freehand group (median [Q1, Q3]: 6.0 [6.0, 9.0] s vs. median [Q1, Q3]: 36.0 [21.5, 48.0] s; χ2 = 13.590, respectively, P < 0.001); no difference in operation time after reduction of the pelvis was noted (χ2 = 1.990, P = 0.158). Time for guide wire insertion was significantly shorter for the robot-assisted group than that for the freehand group (median [Q1, Q3]: 2.0 [2.0, 2.7] min vs. median [Q1, Q3]: 19.0 [15.5, 45.0] min; χ2 = 20.952, respectively, P < 0.001). The number of guide wire attempts in the robot-assisted group was significantly less than that in the freehand group (median [Q1, Q3]: 1.0 [1.0,1.0] time vs. median [Q1, Q3]: 7.0 [1.0, 9.0] times; χ2 = 15.771, respectively, P < 0.001). The instrumented SI levels did not differ between both groups (from S1 to S2, χ2 = 4.760, P = 0.093).Conclusions:Accuracy of the robot-assisted technique was superior to that of the freehand technique. Robot-assisted navigation is safe for unstable posterior pelvic ring stabilization, especially in S1, but also in S2. SI screw insertion with robot-assisted navigation is clinically feasible.