The combination of intraoperative CT navigation and C-arm fluoroscopy for INFIX and percutaneous TITS screw placement in the treatment of pelvic ring injury: technical note

Background The subcutaneous screw rod system, commonly known as the internal pelvic fixator (INFIX), is useful in managing unstable pelvic ring fractures. Conventional INFIX and transiliac–transsacral (TITS) screw techniques are performed using C-arm fluoroscopy. There have been problems with medical exposure and screw insertion accuracy with these techniques. This work describes new INFIX and TITS techniques using intraoperative computed tomography (CT) navigation and C-arm fluoroscopy for pelvic ring fracture. Methods A typical case is presented in this study. An 86-year-old woman suffered from an unstable pelvic ring fracture due to a fall from a height. INFIX and TITS screw fixation with intraoperative CT navigation were selected to optimize surgical invasiveness and proper implant placement. Results The patient was placed in a supine position on a Jackson table. An intraoperative CT navigation was imaged, and screws were inserted under the navigation. Postoperative X-rays and CT confirmed that the screw was inserted correctly. This technique was less invasive to the patient and had little radiation exposure to the surgeon. Rehabilitation of walking practice was started early after the surgery, and she was able to walk with the assistance of a walker by the time of transfer. Conclusions The technique employed in our case study has the cumulative advantages of safety, accuracy, and reduced radiation exposure, together with the inherent advantages of functional outcomes of previously reported INFIX and TITS screw techniques. Further experience with this approach will refine this technique to overcome its limitations and facilitate its wider use.

Improved Accuracy and Safety of Pedicle Screw Placement by Using a Probe with an Electrical Conductivity-Measuring Device during Severe Syndromic and Neuromuscular Scoliosis Spine Surgery

An electrical conductivity-measuring device (ECD) has recently been developed to support pedicle screw placement. However, no evidence exists regarding its efficacy for syndromic/neuromuscular scoliosis with extremely difficult screwing. We retrospectively reviewed 2010–2016 medical records of 21 consecutive syndromic/neuromuscular scoliosis patients undergoing free-hand segmental fixation surgery at our institution and compared the pedicle screw insertion accuracy and safety between 10 with a conventional non-ECD probe (2010–2013) and 11 with an ECD probe (2014–2016). We analyzed preoperative pedicle shape and postoperative screw placement in computed tomography. There were no significant differences between ECD and non-ECD groups in demographic, clinical, and treatment characteristics including scoliosis severity and pedicle diameter. The abandonment rate due to liquorrhea or perforation was lower in ECD (12.3%) than in non-ECD (26.7%) (p < 0.01). Acceptable insertion without perforation or <2-mm lateral/cranial position was more frequent in ECD (67.1%) than in non-ECD (56.9%) (p = 0.02). Critical ≥5-mm medial/caudal malposition was not seen in ECD (0.0%) but in non-ECD (2.4%) (p = 0.02). The perforation distance was shorter in ECD (2.2 ± 1.1 mm) than in non-ECD (2.6 ± 1.7 mm) (p = 0.01). Results involve small sample size, selection, performance, and learning curve biases; nevertheless, ECD could be useful for more accurate and safer pedicle screw placement in severe syndromic/neuromuscular scoliosis.

Medial Pedicle Pivot Point Using Preoperative Computed Tomography Morphometric Measurements for Cervical Pedicle Screw Insertion: A Novel Technique and Case Series

This study describes a new and safe freehand cervical pedicle screw insertion technique using preoperative computed tomography (CT) morphometric measurements as a guide and a medial pedicle pivot point (MPPP) during the procedure. This study included 271 pedicles at 216 cervical spine levels (mean: 4.75 pedicles per patient). A pedicle diameter (PD) ≥ 3.5 mm was the cut-off for pedicle screw fixation. The presence and grade of perforation were detected using postoperative CT scans, where perforations were graded as follows: 0, no perforation; 1, perforation < 0.875 mm; 2, perforation 0.875–1.75 mm; and 3, perforation > 1.75 mm. The surgical technique involved the use of an MPPP, which was the point at which the lines representing the depth of the lateral mass and total length of the pedicle intersected, deep in the lateral mass. The overall success rate was 96.3% (261/271, Grade 0 or 1 perforations). In total, 54 perforations occurred, among which 44 (81.5%) were Grade 1 and 10 (18.5%) were Grade 2. The most common perforation direction was medial (39/54, 72.2%). The freehand technique for cervical pedicle screw fixation using the MPPP may allow for a safe and accurate procedure in patients with a PD ≥3.5 mm.

The proximal humeral locking plate positioning to the pectoralis major tendon in achieving the proper calcar screw location: a cadaveric study

Background Proximal humeral fracture is the third most common of osteoporotic fracture. Most surgical cases were treated by fixation with anatomical locking plate system. The calcar screw plays a role in medial support and improving varus stability. Proximal humerus fracture in elderly patients are commonly seen with greater tuberosity (GT) fracture. The GT fragment is sometimes difficult to use as an anatomic landmark for proper plate and screw position. Therefore, the insertion of pectoralis major tendon (PMT) may be used as an alternative landmark for appropriate plate and calcar screw position. The purpose of study is going to identify the vertical distance from PMT to a definite point on the position of locking plate. Methods 30 cadaveric shoulders at the department of clinical anatomy were performed. Shoulders with osteoarthritic change (n = 5) were excluded. Finally, 25 soft cadaveric shoulders were recruited in this study. The PHILOS™ plate was placed 2 mm posterior to the bicipital groove. A humeral head (HH) was cut in the coronal plane at the level of the anterior border of the PHILOS plate with a saw. A calcar screw was inserted close to the inferior cortex of HH. Distance from the upper border of elongated combi-hole (UB-ECH) to the upper border of pectoralis major tendon (UB-PMT) was measured. The plate was then moved superiorly until the calcar screw was 12 mm superior to the inferior border of HH and the distance was repeatedly measured. Results The range of distance from UB-PMT to the UB-ECH was from − 4.50 ± 7.95 mm to 6.62 ± 7.53 mm, when calcar screw was close to inferior border of HH and when the calcar screw was 12 mm superior to the inferior border of HH, respectively. The highest probability of calcar screw in proper location was 72% when UB-ECH was 3 mm above UB-PMT. Discussion and conclusion The GT fragment is sometimes difficult to use as an anatomic landmark for proper plate and screw position. PMT can be used as an alternative anatomic reference. UB-PMT can serve as a guide for proper calcar screw insertion. UB-ECH should be 3 mm above UB-PMT and three-fourths of cases achieved proper calcar screw location.

CT-to-fluoroscopy registration versus scan-and-plan registration for robot-assisted insertion of lumbar pedicle screws

OBJECTIVE Pedicle screw insertion for stabilization after lumbar fusion surgery is commonly performed by spine surgeons. With the advent of navigation technology, the accuracy of pedicle screw insertion has increased. Robotic guidance has revolutionized the placement of pedicle screws with 2 distinct radiographic registration methods, the scan-and-plan method and CT-to-fluoroscopy method. In this study, the authors aimed to compare the accuracy and safety of these methods. METHODS A retrospective chart review was conducted at 2 centers to obtain operative data for consecutive patients who underwent robot-assisted lumbar pedicle screw placement. The newest robotic platform (Mazor X Robotic System) was used in all cases. One center used the scan-and-plan registration method, and the other used CT-to-fluoroscopy for registration. Screw accuracy was determined by applying the Gertzbein-Robbins scale. Fluoroscopic exposure times were collected from radiology reports. RESULTS Overall, 268 patients underwent pedicle screw insertion, 126 patients with scan-and-plan registration and 142 with CT-to-fluoroscopy registration. In the scan-and-plan cohort, 450 screws were inserted across 266 spinal levels (mean 1.7 ± 1.1 screws/level), with 446 (99.1%) screws classified as Gertzbein-Robbins grade A (within the pedicle) and 4 (0.9%) as grade B (< 2-mm deviation). In the CT-to-fluoroscopy cohort, 574 screws were inserted across 280 lumbar spinal levels (mean 2.05 ± 1.7 screws/ level), with 563 (98.1%) grade A screws and 11 (1.9%) grade B (p = 0.17). The scan-and-plan cohort had nonsignificantly less fluoroscopic exposure per screw than the CT-to-fluoroscopy cohort (12 ± 13 seconds vs 11.1 ± 7 seconds, p = 0.3). CONCLUSIONS Both scan-and-plan registration and CT-to-fluoroscopy registration methods were safe, accurate, and had similar fluoroscopy time exposure overall.

Acetabular Migration of Lag Screw of Intramedullary Nail Used as Treatment for Intertrochanteric Fracture. Case Study

Most trochanteric fractures of the femur are classified as low-energy fractures as they are seen in people with decreased mechanical properties of bone tissue. The treatment is assumed to provide biomechanical fixation with the possibility of dynamization between bony fragments to stimulate the biological processes of bone union. The aim of the study was to analyze a complication presenting as migration of the cervical screw of an intra­medullary nail towards the hip joint acetabulum and present the therapeutic management of this complication. The case report concerned a 74-year-old patient with an AO/OTA type 31 A2.2 fracture of the trochanteric massif of the right femur treated with the Gamma3 intramedullary nail. An assessment of changes over time of the radiological appearances on A-P images after the surgery showed migration of the cervical screw towards the acetabulum and displacement of the major trochanter fracture. Extensive destruction of the acetabular fossa made biologic restorative treatment impossible. A total hip joint prosthesis with a modular stem and MDM articulation was implan­ted and the trochanter was fixed with a "hook" plate with a "cable system". The postoperative course was uneventful. Failure to perform axial radiographs in the preoperative and postoperative period made it impossible to objectively determine the type of fracture and the quality of screw insertion into the femoral neck, and assessment limited to A-P images turned out to be deceptive. The wandering of the screw towards the acetabulum led to extensive destruction of the acetabular fossa. The decision to stop biological treatment, which, if properly performed, stimulates bone union, and perform the mechanical procedure of endoprosthesoplasty was fully prognostically justified. The early and late postoperative course was not complicated.

Does the application of Robotics improve outcomes of pedicle screw insertion in spine surgery compared to conventional fluoroscopy guidance? A protocol for Systematic Review and Meta-Analysis

BackgroundPedicle screw insertion is routinely carried out in spine surgery that has traditionally been performed under fluoroscopy guidance. Robotic guidance has recently gained popularity in order to improve the accuracy of screw placement. However, it is unclear whether the use of robotics alters the accuracy of screw placement or clinical outcomes.ObjectivesThis systematic review aims to compare the results of pedicle screws inserted under fluoroscopy guidance, with those inserted under robotic guidance, in terms of both short-term radiographic outcomes, as well as long-term clinical outcomes.MethodsThis systematic review will be conducted according to the PRISMA guidelines. A literature search will be conducted on the electronic databases of PubMed, Embase, Scopus, and Ovid with a pre-determined search strategy. A manual bibliography search of included studies will also be done. Original articles in English that directly compare pedicle screw insertion under robotic guidance to those inserted under fluoroscopy guidance will be included. Data on outcomes will be extracted from included studies and analysis carried out with the help of appropriate software.

Comparison of Robot Versus Fluoroscopy-Assisted Pedicle Screw Instrumentation in Adolescent Idiopathic Scoliosis Surgery

The aim of this study is to explore whether robot-assisted technique has advantages over conventional fluoroscopy-assisted technique in clinical and radiological outcomes and whether it could decrease the incidence of mis-implantations of pedicle screws in AIS correction surgery.A total of 101 AIS patients were recruited (RA group: 45 patients underwent robot-assisted screw insertion; FA group: 56 patients underwent fluoroscopy-assisted screw insertion). When compared the radiological data between two groups, major and secondary curve were both corrected proficiently with no difference in the Cobb angle comparison at last follow-up, suggesting that both robot-assisted technique and fluoroscopy-assisted technique could lead to efficient radiographic correction and similar clinical outcomes (all, P<0.05). In RA group, operation time, blood loss and transfusion volume were significantly greater than those in FA group, while the accuracy of screw implantations in AIS patients with thoracic scoliotic curve in RA group was higher than that in FA group.In conclusion, both robot-assisted and fluoroscopy-assisted technique could reach proficient radiographic correction and similar clinical outcomes in AIS surgery. Compared with conventional fluoroscopy technique, robot-assisted technique might improve the accuracy of screw implantations in AIS patients with thoracic scoliotic curve, while the increased operation time, blood loss and transfusion volume might be the disadvantages due to preliminary stage of learning curve.

A 3-dimensional finite element analysis to evaluate the impact of force direction, insertion angle, and cortical bone thickness on mini-screw and its surrounding bone

Background. The present study aimed to assess the stress and strain distribution on mini-screws and the surrounding bone in cases of different cortical bone thicknesses (CBTs), mini-screw insertion angles, and force directions using finite element analysis (FEA). Methods. Inventor professional version 8 software was used to construct 24 three-dimensional assemblies of mini-screws inserted with different insertion angles (30º, 60º, and 90º) in alveolar bone blocks with different CBTs (0.5, 1, 1.5, and 2 mm). The models simulated mini-screws inserted in bones with different CBTs and different insertion angles. A 2-N load was applied in two directions to mini-screw heads. The resultant stresses of the applied load were collected from the output of the ANSYS program. Results. The results indicated that force direction affected bone strains as the horizontal force generated more strains on cortical bone than the oblique one. Force applied to 60º inserted mini-screws generated much more strains on cortical bone than 90º and 30º inserted mini-screws. In a 60º inserted mini-screw, the horizontal force generated about 45% more strains on cortical bone than the oblique one. The exerted microstrain on bone decreased as CBT increased. Conclusion. It can be concluded that inserting mini-screws at 60º to the bone surface should be avoided as it generates much more strains on cortical bone than 90º and 30º, especially when a force parallel to the bone surface is applied.

Fully arthroscopic treatment of medial Hoffa fracture associated with anterior cruciate ligament tear: case report and surgical technique

A Hoffa fracture is a rare intra-articular injury consisting of a coronal plane fracture of one or both of the distal femoral condyles. Because of the rarity of medial Hoffa fractures, only a few reports have described this injury and its arthroscopic management. In this article, we present a rare case involving a 32-year-old man with a displaced medial Hoffa fracture associated with a proximal anterior cruciate ligament tear. He was treated by a single-stage fully all-inside arthroscopic technique. Arthroscopic-assisted internal fixation ensured fragment stability and enabled us to visualize the fracture reduction, monitor the screw insertion, and reconstruct the anterior cruciate ligament tear at the same time. This technique is a novel but demanding treatment method for medial Hoffa fractures and is particularly useful for properly selected patients with associated intra-articular knee injuries.