Percutaneous Screw Placement Research Articles

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.

Scaphoid screw placement under minimal radiation exposure

BackgroundPercutaneous scaphoid fixation through either a volar or dorsal approach has the advantage of minor soft tissue damage compared with ORIF, and faster fracture union compared with conservative treatment. However, this technique demands highly intraoperative reliance on X-ray control, including increased radiation exposure and all associated side effects. PurposeTo test the possibility and efficacy of volar percutaneous scaphoid screw placement under minimalradiation exposure. MethodsThe sample included 20 hands (seven left, 13 right) from human adult cadavers. For this study, the utilised wrists were assumed to have non-displaced scaphoid fractures. Using a percutaneous approach, a 2-mm Kirschner wire (K-wire) was advanced to the distal pole of the scaphoid and placed in a 45° horizontal and vertical angle under monitoring with the C-arm. The K-wire was inserted blindly alongside the estimated length of the scaphoid. Following K-wire insertion, four X-rays were taken to depict K-wire positioning and to assess positioning alongside the axis of the scaphoid and K-wire protrusion. The rating scale comprised 1 (good), 2 (moderate) or 3 (poor). ResultsAll tested radiographic views were evaluated with a median of 2 points (moderate position) regardingplacement alongside the scaphoid axis. ConclusionOur results indicate that percutaneous scaphoid fixation with the guide wire placed in a 45° horizontal and vertical angle enables primary moderate positioning, which may lead to quicker adjustment to the ideal position and a decrease of radiation exposure.

Percutaneous pedicle screw placement under single dimensional fluoroscopy with a designed pedicle finder—a technical note and case series

Background ContextMinimally invasive spine surgery has become increasingly popular in clinical practice, and it offers patients the potential benefits of reduced blood loss, wound pain, and infection risk, and it also diminishes the loss of working time and length of hospital stay. However, surgeons require more intraoperative fluoroscopy and ionizing radiation exposure during minimally invasive spine surgery for localization, especially for guidance in instrumentation placement. In addition, computer navigation is not accessible in some facility-limited institutions. PurposeThis study aimed to demonstrate a method for percutaneous screws placement using only the anterior-posterior (AP) trajectory of intraoperative fluoroscopy. Study DesignA technical report (a retrospective and prospective case series) was carried out. Patient SamplePatients who received posterior fixation with percutaneous pedicle screws for thoracolumbar degenerative disease or trauma comprised the patient sample. MethodWe retrospectively reviewed the charts of consecutive 670 patients who received 4,072 pedicle screws between December 2010 and August 2015. Another case series study was conducted prospectively in three additional hospitals, and 88 consecutive patients with 413 pedicle screws were enrolled from February 2014 to July 2016. The fluoroscopy shot number and radiation dose were recorded. In the prospective study, 78 patients with 371 screws received computed tomography at 3 months postoperatively to evaluate the fusion condition and screw positions. ResultsIn the retrospective series, the placement of a percutaneous screw required 5.1 shots (2–14, standard deviation [SD]=2.366) of AP fluoroscopy. One screw was revised because of a medialwall breach of the pedicle. In the prospective series, 5.8 shots (2–16, SD=2.669) were required forone percutaneous pedicle screw placement. There were two screws with a Grade 1 breach (8.6%), both at the lateral wall of the pedicle, out of 23 screws placed at the thoracic spine at T9–T12. Forthe lumbar and sacral areas, there were 15 Grade 1 breaches (4.3%), 1 Grade 2 breach (0.3%), and 1 Grade 3 breach (0.3%). No revision surgery was necessary. ConclusionThis method avoids lateral shots of fluoroscopy during screw placement and thus decreases the operation time and exposes surgeons to less radiation. At the same time, compared with the computer-navigated procedure, it is less facility-demanding, and provides satisfactory reliability and accuracy.

Evaluation of robot-guided minimally invasive implantation of 2067 pedicle screws

Objective Recent studies have investigated the role of spinal image guidance for pedicle screw placement. Many authors have observed an elevated placement accuracy and overall improvement of outcome measures. This study assessed a bi-institutional experience following introduction of the Renaissance miniature robot for spinal image guidance in Europe. Methods The medical records and radiographs of all patients who underwent robot-guided implantation of spinal instrumentation using the novel system (between October 2011 and March 2015 in Mainz and February 2014 and February 2016 in Regensburg) were reviewed to determine the efficacy and safety of the newly introduced robotic system. Screw position accuracy, complications, exposure durations to intraoperative radiation, and reoperation rate were assessed. Results Of the 413 surgeries that used robotic guidance, 406 were via a minimally invasive approach. In 7 cases the surgeon switched to conventional screw placement, using a midline approach, due to referencing problems. A total of 2067 screws were implanted using robotic guidance, and 1857 screws were evaluated by postoperative CT. Of the 1857 screws, 1799 (96.9%) were classified as having an acceptable or good position, whereas 38 screws (2%) showed deviations of 3-6 mm and 20 screws (1.1%) had deviations > 6 mm. Nine misplaced screws, implanted in 7 patients, required revision surgery, yielding a screw revision rate of 0.48% of the screws and 7 of 406 (1.7%) of the patients. The mean ± SD per-patient intraoperative fluoroscopy exposure was 114.4 (± 72.5) seconds for 5.1 screws on average and any further procedure required. Perioperative and direct postoperative complications included hemorrhage (2 patients, 0.49%) and wound infections necessitating surgical revision (20 patients, 4.9%). Conclusions The hexapod miniature robotic device proved to be a safe and robust instrument in all situations, including those in which patients were treated on an emergency basis. Placement accuracy was high; peri- and early postoperative complication rates were found to be lower than rates published in other series of percutaneous screw placement techniques. Intraoperative radiation exposure was found to be comparable to published values for other minimally invasive and conventional approaches.

Development of an Enhanced Recovery After Surgery (ERAS) approach for lumbar spinal fusion.

OBJECTIVE Over the past decade, Enhancing Recovery After Surgery (ERAS) programs have been implemented throughout the world across multiple surgical disciplines. However, to date no spinal surgery equivalent has been described. In this report the authors review the development and implementation of a "fast track" surgical approach for lumbar fusion. METHODS The first 42 consecutive cases in which patients were treated with the new surgical procedure were reviewed. A combination of endoscopic decompression, expandable cage deployment, and percutaneous screw placement were performed with liposomal bupivacaine anesthesia to allow the surgery to be performed without general endotracheal anesthesia. RESULTS In all cases the surgical procedure was performed successfully without conversion to an open operation. The patients' mean age (± SD) was 66.1 ± 11.7 years, the male/female ratio was 20:22, and a total of 47 levels were treated. The mean operative time was 94.6 ± 22.4 minutes, the mean intraoperative blood loss was 66 ± 30 ml, and the mean hospital length of stay was 1.29 ± 0.9 nights. Early follow-up showed a significant improvement in the mean Oswestry Disability Index score (from 40 ± 13 to 17 ± 11, p = 0.0001). Return to the operating room was required in 2 cases due to infection and in 1 case due to cage displacement. An iterative quality improvement program demonstrated areas of improvement, including steps to minimize infection, improve postoperative analgesia, and reduce cage osteolysis. CONCLUSIONS ERAS programs for improving spinal fusion surgery are possible and necessary. This report demonstrates a first foray to apply these principles through 1) a patient-focused approach, 2) reducing the stress of the operation, and 3) an iterative improvement process.

Percutaneous Treatment of Unstable Scaphoid Waist Fractures.

Percutaneous techniques have been described for the treatment of nondisplaced scaphoid fractures, although less information has been reported about outcomes for unstable, displaced fractures. The aim of this study was to evaluate the union and complication rates following manual closed reduction and percutaneous screw placement for a consecutive series of unstable, displaced scaphoid fractures. A total of 28 patients (average age, 27 years; 22 male/6 female) were treated for isolated unstable displaced scaphoid waist fractures. Closed reduction and percutaneous headless, compression screw fixation was successfully performed in 14 patients (average age, 32 years; 10 male/4 female), and the remaining 14 patients required open reduction. Patients who underwent percutaneous treatment were followed for radiographic fracture union and clinical outcomes. Thirteen of 14 fractures (93%) had clinical and radiographic evidence of bone union at an average of 2.8 months postoperatively. Average visual analog pain score at the time of union was 0.9. The average Quick Disability of the Arm, Shoulder, and Hand score at 2.5 years follow-up (range, 1.5-8.3 years) was 9.6 (range, 0.0-27.3). Complications included 1 case of nonunion and 1 case of intraoperative Kirschner wire breakage. Manual closed reduction followed by percutaneous headless, compression screw fixation was possible in 50% of patients who presented with acute unstable, displaced scaphoid fractures. This technique appears to be a safe and effective method when a manual reduction is possible, and it may offer a less invasive option when compared with a standard open technique.

Three-dimensional navigation for placement of percutaneous sacroiliac joint screws in internal fixation of sacroiliac complex injury

Objective To investigate the clinical results of three-dimensional navigation for placement of percutaneous sacroiliac joint screws in the internal fixation of sacroiliac complex injury. Methods A retrospective study was conducted of the 30 patients who had been treated for sacroiliac complex injury from March 2015 to January 2016 and fully followed up. They were 22 males and 8 females, aged from 25 to 63 years (average, 44.2 years). According to Tile classification for pelvic fractures, there were 14 cases of type B (type B1 in 6, type B2 in 6 and type B3 in 2), and 16 cases of type C (type C1 in 9, type C2 in 5, and type C3 in 2). Three cases complicated with preoperative injury to lumbosacral trunk were treated with anterior plate and percutaneous sacroiliac joint screws; the other 27 cases with internal fixation with percutaneous sacroiliac joint screws. The placement of screws was aided by three-dimensional navigation. The time for each screw placement and X-ray exposure was recorded intraoperatively. Postoperative reduction quality was assessed using Matta radiological criteria and Majeed criteria was used at the final follow-ups to evaluate the pelvic function. Results Altogether 36 sacroiliac joint screws were inserted in the 30 patients under three-dimensional navigation. The time for each screw placement ranged from 28 to 40 minutes (average, 33.2 minutes); the intraoperative X-ray exposure time ranged from 1.2 to 2.5 minutes (average, 1.4 minutes). No infection occurred at either incision or placement site. According to Matta radiological criteria, reduction was excellent in 16, good in 11 and fair in 3, giving an excellent to good rate of 90.0%. The follow-up time for the 30 patients ranged from 6 to 12 months (average, 10.6 months). At the final follow-ups, X-ray and CT three-dimensional reconstruction showed fine fracture union and no loosening or breakage of screws in all. By the Majeed criteria, the pelvic function was excellent in 17 cases, good in 8 cases, fair in 4 cases, and poor in one, giving a good to excellent rate of 83.3%. Conclusion Three-dimensional navigation for placement of percutaneous sacroiliac joint screws in internal fixation of sacroiliac complex injury can lead to precise placement, minimal invasion, safety and effectiveness. Key words: Sacroiliac joint; Wounds and injuries; Fracture fixation, internal; Bone nails; Surgery, computer-assisted

Etiology and Treatment of Delayed-Onset Medial Malleolar Pain Following Total Ankle Arthroplasty.

Total ankle arthroplasty (TAA) has become a successful treatment for end-stage ankle arthritis. Some patients may still have pain or may present with new pain. Suggested sources of medial pain include tibialis posterior tendonitis, impingement, or medial malleolar stress fracture. Etiology and treatment remain unclear. The objective of our study was to evaluate patients with delayed-onset medial malleolar pain following TAA who underwent treatment with percutaneous medial malleolar screw placement and propose an etiology. Patients who had undergone TAA at our institution were reviewed and those with medial malleolar pain were identified. Clinical and radiographic examinations were performed pre- and postoperatively. Radiographs were compared with those from a cohort of controls without a history of medial pain. All affected patients failed conservative therapy and were treated with percutaneous placement of medial malleolar screws positioned from the malleolar tip and extending proximally beyond the tibial component. Postoperatively, patients were placed in an ace wrap and allowed to be weightbearing to tolerance, except for 1 patient initially restricted to partial weightbearing. Visual analog scale (VAS) scores were recorded. Seventy-four (74) patients underwent TAA by the corresponding author. All (100%) were female with an average age of 66 (range, 57-73) years. Average follow-up since screw placement was 21.4 (range, 10-41) months. Six (8.1%) underwent placement of 2 percutaneous medial malleolar screws. Patients presented with pain an average of 12 (range, 4-24) months postoperatively and underwent screw placement an average of 2.8 (range, 1-6) months after presentation. At the time of TAA, none had a coronal plane deformity and none underwent a deltoid ligament release as part of balancing. All (100%) patients had pain and swelling directly over the medial malleolus prior to screw placement. Postoperatively, 1 (17%) had mild pain clinically at this site and 2 (33%) had occasional pain medially with activity. Average VAS scores improved from 5.7 (range, 4-6) preoperatively to 1.3 (range, 0-3) postoperatively (P < .05). Three (50%) patients had a bone density test and all were normal. Prior to screw placement, radiographs demonstrated no signs of stress fracture or misalignment. Average minimum width of the medial malleolus at the level of the tibial component was 10.2 mm (range, 9.2-11.0), which was significantly less (P < .05) than the control group of 19 patients whose distance measured 12.2 mm (range, 8.5-14.8). Patients who present with new-onset medial malleolar pain with normal radiographs following TAA may have medial malleolar insufficiency fracture. These patients can be treated successfully with minimal morbidity by placement of percutaneous medial malleolar screws. Etiology may be related to deltoid traction, subacute stress fracture, and/or impingement of the talus component on the medial malleolus. Medial malleolar pain may be misdiagnosed as tibialis posterior tendonitis, impingement, or implant failure. This diagnosis should be considered in patients who have pain at the medial malleolus, particularly if they are female or have medial malleolus thickness less than 11 mm at the level of the tibial implant. Placement of prophylactic medial malleolar screws may be considered at the time of TAA when these conditions exist. Level IV, case series.

Image-guided Spine Stabilization for Traumatic Or Osteoporotic Spine Injury: Radiological Accuracy and Neurological Outcome.

Significant progress has been made in image-guided surgery (IGS) over the last few decades. IGS can be effectively applied to spinal instrumentation surgery. In the present study, we focused our attention on the feasibility and safety of image-guided spine stabilization for traumatic or osteoporotic spine injury. The IGS spine fixation with or without minimally invasive surgery (MIS) techniques such as percutaneous screw placement, balloon kyphoplasty (BKP), or vertebroplasty (VP) were accomplished in 80 patients with traumatic or osteoprotic spine injury between 2007 and 2015. The injured vertebral levels included the following: cervical spine, 41; thoracic spine, 22; and lumbar spine, 17. Neurological condition before and after surgery was assessed using the American Spinal Injury Association Impairment Scale (AIS). A total of 419 pedicle, lateral mass, or laminar screws were placed, and 399 screws (95.2%) were found to be placed correctly based on postoperative computed tomography scan. Although 20 screws (4.8%) were found to be unexpectedly placed incorrectly, no neural or vascular complications closely associated with screw placement were encountered. Neurological outcomes appeared to be acceptable or successful based on AIS. The IGS is a promising technique that can improve the accuracy of screw placement and reduce potential injury to critical neurovascular structures. The integration of MIS and IGS has proved feasible and safe in the treatment of traumatic or osteoporotic spine injury, although a thorough knowledge of surgical anatomy, spine biomechanics, and basic technique remain the most essential aspects for a successful surgery.

Computer Assisted Surgery for Iliosacral Screw Placement-How Far have we gone?

Unstable pelvic ring injuries require definite operative fixation. While the posterior ring can be fixed utilizing open approaches, percutaneous screw fixation has become the treatment of choice avoiding the complications of open approaches. As the pelvis is a complex three-dimensional (3D) shape with many neurovascular structures situated within it, a thorough knowledge and understanding of the anatomy and radiographic imaging is required to accomplish the task of percutaneous iliosacral screw placement, while avoiding potential complications. Recent advances in computer assisted surgery (CAS) has provided some powerful tools in overcoming the obstacles associated with this procedure. This review examines the evolution of image guided surgery used for iliosacral screw placement, the current available options, and future perspectives.

Accuracy of thoracolumbar transpedicular and vertebral body percutaneous screw placement: coupling the Rosa® Spine robot with intraoperative flat-panel CT guidance--a cadaver study.

The primary objective of the present study was to evaluate the accuracy of a new robotic device when coupled with intraoperative flat-panel CT guidance. Screws (D8-S1) were implanted during two separate cadaver sessions by coupling the Rosa(®) Spine robot with the flat-panel CT device. Of 38 implanted screws, 37 (97.4 %) were fully contained within the pedicle. One screw breached the lateral cortical of one pedicle by <1 mm. The mean ± SD accuracy (relative to pre-operative planning) was 2.05 ± 1.2 mm for the screw head, 1.65 ± 1.11 for the middle of the pedicle and 1.57 ± 1.01 for the screw tip. When coupled with intraoperative flat-panel CT guidance, the Rosa(®) Spine robot appears to be accurate in placing pedicle screws within both pedicles and the vertebral body. Large clinical studies are mandatory to confirm this preliminary cadaveric report.

Image-guided percutaneous internal fixation of sacral fracture

Percutaneous iliosacral screw placement is a technically challenging procedure with a significant complication profile for misplaced screws. The use of stereotactic image guidance has been shown to provide superior accuracy in the placement of spinal instrumentation. Here, the authors describe a novel application of O-arm technology (Medtronic Sofamor Danek, Memphis, TN, USA) to help safely place iliosacral screws for the treatment of a traumatic sacral fracture.

Virtual mapping of 260 three-dimensional hemipelvises to analyse gender-specific differences in minimally invasive retrograde lag screw placement in the posterior acetabular column using the anterior pelvic and midsagittal plane as reference

BackgroundDue to complex pelvic geometry, percutaneous screw placement in the posterior acetabular column can pose a major challenge even for experienced surgeons.MethodsThe present study examined the preformed bone stock of the posterior acetabular column in 260 hemipelvises. Retrograde posterior column screws were virtually implanted using iPlan® CMF (BrainLAB AG, Feldkirchen, Germany); maximal implant length, maximal implant diameter and angles between the screw trajectories and the reference planes anterior pelvic plane as well as the midsagittal plane were assessed for gender-specific differences.ResultsThe virtual analysis of the preformed bone stock column showed two constrictions of crucial clinical importance. These were located 49.6 ± 3.4 (41.0–60.2) mm (inferior margin of acetabulum) and 77.0 ± 5.6 (66.5–95.3) mm (centre of acetabulum) from the entry point of the implant in men and respectively 43.7 ± 2.3 (38.3–49.3) mm as well as 71.2 ± 3.5 (63.5–79.99) mm in women (men vs. women: p < 0.001). The entry point of the retrograde posterior column screw was located dorsal from the transition of the lower margin of the ischial tuberosity to ramus inferior pointing to the medial margin of the ischial tuberosity. In female patients, the entry point was located significantly closer to the medial margin of the ischial tuberosity. However, 7.3 mm screws can generally be used in men and women. The angle between the screw trajectory and the anterior pelvic plane in sagittal section was 14.0 ± 4.9 (2.5–28.6) °, the angle between the screw trajectory and the midsagittal plane in axial section was 31.1 ± 12.8 (1.5–77.9) ° and the angle between the screw trajectory and the midsagittal plane in coronal section was 8.4 ± 3.8 (1.5–20.0) °. For all angles, significant gender-specific differences were found (p < 0.001).ConclusionTherefore, the anterior pelvic plane as well as the midsagittal plane can facilitate intraoperative orientation for retrograde posterior column screw placement considering gender-specific differences in preformed bone corridor, implant length as well as angles formed between screw trajectory and these reference planes.

Correlating preoperative imaging with intraoperative fluoroscopy in iliosacral screw placement

BackgroundPercutaneous iliosacral screw placement can successfully stabilize unstable posterior pelvic ring injuries. Intraoperative fluoroscopic imaging is a vital component needed in safely placing iliosacral screws. Obtaining and appropriately interpreting fluoroscopic views can be challenging in certain clinical scenarios. We report on a series of patients to demonstrate how preoperative computed tomography (CT) imaging can be used to anticipate the appropriate intraoperative inlet and outlet fluoroscopic views.Materials and methods24 patients were retrospectively identified with unstable pelvic ring injuries requiring operative fixation using percutaneous iliosacral screws. Utilizing the sagittal reconstructions of the preoperative CT scans, anticipated inlet and outlet angle measurements were calculated. The operative reports were reviewed to determine the angles used intraoperatively. Postoperative CT scans were reviewed for repeat measurements and to determine the location and safety of each screw.ResultsPreoperative CT scans showed an average inlet of 20.5° (7°–37°) and an average outlet of 42.8° (30°–59°). Intraoperative views showed an average inlet of 24.9° (12°–38°) and an average outlet of 42.4° (29°–52°). Postoperative CT scans showed an average inlet of 19.4° (8°–31°) and an average outlet of 43.2° (31°–56°). The average difference from preoperative to intraoperative was 4.4° (−21° to 5°) for the inlet and 0.45° (−9° to 7°) for the outlet. The average difference between the preoperative and postoperative CT was 2.04° (0°–6°) for the inlet and 2.54° (0°–7°) for the outlet.ConclusionThere is significant anatomic variation of the posterior pelvic ring. The preoperative CT sagittal reconstruction images allow for appropriate preoperative planning for anticipated intraoperative fluoroscopic inlet and outlet views within 5°. Having knowledge of the desired intraoperative views preoperatively prepares the surgeon, aids in efficiently obtaining correct intraoperative views, and ultimately assists in safe iliosacral screw placement.Level of evidenceIV, Retrospective case series.

Minimally Invasive Percutaneous Iliac Screws

Percutaneous pedicle screws have become accepted as an effective method for segmental fixation in a variety of settings. However, fixation to the pelvis, which offers unique biomechanical advantages, had remained elusive from a minimally invasive approach. To ascertain the safety of percutaneous iliac screws implanted placement using fluoroscopic guidance. In an effort to verify the accuracy of a fluoroscopically guided technique for safe iliosacral screw placement, we reviewed the imaging results from 24 consecutive patients undergoing this procedure. Percutaneous iliac screw placement was accomplished using primarily x-ray-guided screw insertion (obturator outlet view technique) without frameless image-guidance and with limited exposure of bony landmarks or tactile feedback. Indications for surgery included infection, neoplasia, trauma, and deformity. All patients underwent early postoperative computed tomography scanning to determine the accuracy of screw positioning. A total of 24 patients had 47 screws placed for fixation at the lumbosacral junction. No cases required abortion of the procedure or conversion to an open operation. All of the percutaneous screws were placed appropriately as verified by postoperative computed tomography scanning with 3-dimensional reconstruction. There were no hardware-related complications. However, one 75-year-old patient suffering a sacral fracture died of medical comorbidities on postoperative day 10. A minimally invasive technique for iliac screw placement can be performed safely with a low likelihood of bony violation. This technique offers the unique biomechanical advantages of iliac fixation without the soft-tissue exposure traditionally needed for safe hardware insertion. The technique relies on high-quality intraoperative fluoroscopic imaging.

Fluoroscopically assisted computer navigation enables accurate percutaneous screw placement for pelvic and acetabular fracture fixation

Percutaneous fixation of pelvic and acetabular fractures are technically demanding procedures, and high rates of screw misplacement and potential neurovascular complications have been reported.One hundred and sixty two screws from a prospectively collected database were analysed to evaluate the accuracy of a fluoroscopically assisted computer navigated technique to insert a cannulated screw to treat pelvic and acetabular fractures. Actual screw position and trajectory with the intraoperative surgical plan stored in the navigation computer.The actual screw position differed from the surgical plan by a mean of 3.9mm, with a mean 1.4 degree difference in screw trajectory. Post operative CT analysis of patients showed 10 screws perforated cortical bone.Our results show that the use of computer navigation can aid in the accurate placement of percutaneous screws along a predefined plan. It is still possible to incorrectly place a screw and great care needs to be taken with the surgical plan and also to understand the complex anatomy of the bony pelvis.

Computer-assisted navigation for percutaneous scaphoid screw placement: A preliminary study

Objective To investigate the feasibility of a new computer-assisted navigation frame for percutaneous scaphoid screw placement.Methods Two fresh cadaveric upper limbs were used for percutaneous scaphoid screw placement under ISO-C3D navigation system combined with a new positioning and guidance frame.The specimens were assessed grossly and radiologically.Results Scaphoid screw placement was performed successfully using this new navigation system.Only one attempt was required for percutaneous guide wire insertion and the screws were within the safe zone of the scaphoid for both of the specimens.Conclusion This preliminary study proved the feasibility of percutaneous scaphoid screw placement using this new computer-assisted navigation frame.The accuracy and stability of this system can meet the requirement of percutaneous scaphoid screw placement in this study. Key words: Scaphoid ; Percutaneous screw placement ; Computer-assisted navigation ; Digital medicine

Axial view of acetabular anterior column: a new X-ray projection of percutaneous screw placement.

To search for a new radiographic view/projection of the acetabular anterior column to provide a safe guide for percutaneous screw placement for acetabular fractures. Eight pelvic specimens taken from normal adult cadavers were positioned in a supine position on the operating table. First, the ipsilateral ilium-oblique view of the observed side was obtained on C-arm fluoroscopy by tilting the C-arm approximately 35° toward the contralateral hip joint. Then, the tilting angle of the C-arm was changed gradually until an oval track image (acetabular anterior column axial view) appeared. The oval shadow was clear only in one position as the angle of the C-arm was changed toward the caudal side of the operating table. A guide pin was put on the skin of the cadaver, and the location and tilting direction of the guide pin were adjusted under C-arm fluoroscopy until the pin's shadow became a point in the center of the oval track. Then, the guide pin was inserted into the bone using a battery-powered drill. The degree of inclination of the guide pin in the cadaver in the frontal and sagittal planes was measured using computed tomography (CT). Axial views of the anterior column were found successfully in all of the pelvic specimens, and the guide pins were inserted accurately into the acetabular anterior column under C-arm fluoroscopic guidance. On the CT-reconstructed image, the average degree of angle between the guide pin and the sagittal plane was 33.6° (range 29.6°-36.5°). The average angle between the guide pin and the transverse plane was 59.1° (range 56.4°-63.2°). This axial view of the acetabular anterior column is a novel X-ray projection which provides an optimal method for guiding percutaneous insertion of anterior column screws for acetabular fractures.

CT-guided sacroiliac percutaneous screw placement in unstable posterior pelvic ring injuries: Accuracy of screw position, injury reduction and complications in 71 patients with 136 screws

BackgroundSacroiliac-percutaneous-screw-placement (SPSP) for unstable-posterior-pelvic-ring-injuries (UPPRI) might be associated with severe neurovascular complications because of screw-mal-position. The aim of the present study was to analysis the effectivity of computer-tomography-guided (CTG)-SPSP including accuracy of screw-placement, quality of injury-reduction and documentation of perioperative-complications. Additionally, procedure-dependent radiation-dose and outcome should be analysed. MethodsA consecutive cohort of 71 patients with UPPRI was operated by CTG-SPSP at a single trauma level 1 hospital. 136 sacroiliac screws were inserted to S1 and S2. Postoperatively, by the use of a computerised-radiologic-work-station all screws were visualised three-dimensionally. Their distancesmin to the sacral-borders in anterior-posterior and cranio-caudal direction as well as to the neuroforamen S1/S2 were determined. After CTG-SPSP, injury-dislocation in anterior-posterior and cranio-caudal direction was quantified. Local and general complications were documented during the 30-day-period. In 55 patients (77.5%) a follow-up-investigation (29.1±19.1 months) was performed. Results132 screws (97.1%) were placed completely intraosseous, 3 screws (2.2%) perforated up to 1.0mm (n(S1)=one screw; n(S2)=two screws), and one screw (0.7%) extended 2.2mm into the S2-neuroforamen without contact to neural structures. Postoperative dislocationanterior-posterior was 1.3±0.9mm and dislocationcranio-caudal 1.5±0.9mm. No procedure-associated-complication was observed. Operation time showed a significant “learning curve” during the six-year study period (initially: 88.6±60.3min; finally: 44.3±24.6min). Perioperative effective-radiation-dose for patientsmale was 5.9±3.1mSv and for patientsfemale 8.7±4.5mSv. All injuries healed and 33 patients (46.5%) had metal removal after 11.0 (±4.9) months. Only two (5.0%) out of 40 patients complained persistent UPPRI-related pain so they were not able to restart work. ConclusionsThe CTG-SPSP is a safe procedure for UPPRI-stabilisation especially in S1 but also in S2. Injury reduction was excellent and no procedure associated complications were observed.

Lumbar spine superior-level facet joint violations: percutaneous versus open pedicle screw insertion using intraoperative 3-dimensional computer-assisted navigation

Background Percutaneous pedicle screw use has a high rate of cranial facet joint violations (FVs) because of the facet joint being indirectly visualized. Computer-assisted navigation shows the anatomic structures clearly, and may help to lower the rate of FVs during pedicle screw insertion. This study used computed tomography (CT) to evaluate and compare the incidence of FVs between percutaneous and open surgeries employing computer-assisted navigation for the implantation of pedicle screw instrumentation during lumbar fusions. Methods A prospective study, including 142 patients having lumbar and lumbosacral fusion, was conducted between January 2013 and April 2014. All patients had bilateral posterior pedicle screw-rod instrumentation (top-loading screws) implanted by the same group of surgeons; intraoperative 3-dimensional computer navigation was used during the procedures. All patients underwent CT examinations within 6 months postoperation. The CT scans were independently reviewed by three reviewers blinded to the technique used. Results The cohort comprised 68 percutaneous and 74 open cases (136 and 148 superior-level pedicle screw placements, respectively). Overall, superior-level FVs occurred in 20 patients (20/142, 14.1%), involving 27 top screws (27/284, 9.5%). The percutaneous technique (7.4% of patients, 3.7% of top screws) had a significantly lower violation rate than the open procedure (20.3% of patients, 14.9% of top screws). The open group also had significantly more serious violations than did the percutaneous group. Both groups had a higher violation rate when the cranial fixation involved the L5. A 1-level open procedure had a higher violation rate than did the 2- and 3-level surgeries. Conclusions With computer-assisted navigation, the placement of top-loading percutaneous screws carries a lower risk of adjacent-FVs than does the open technique; when FVs occur, they tend to be less serious. Performing a single-level open lumbar fusion, or the fusion of the L5-S1 segment, requires caution to avoid cranial adjacent FVs.