Abnormal Pedicles Research Articles

Using Technique and Technology to Improve Safety and Outcomes in AIS: A Review of 12,795 Screws in Pediatric Spine Deformity.

Retrospective Cohort Study. This study aimed to compare outcomes in AIS patients that underwent PSF using either freehand with occasional fluoroscopic assistance (FOFA), computer assisted surgery/navigation (CAS), or technique and technology (T&T). Pedicle screw insertion in scoliosis is challenging due to abnormal pedicle morphology. Fluoroscopic guidance was frequently utilized, until technological advancements led to the adaptation of computer assisted screw insertion. While improvement in screw accuracy has been documented, an increase in radiation exposure, surgical time, and blood loss can occur. This institution adopted a T&T, or technique and technology, approach that combines freehand technique with CT-based navigation technology for confirmation and navigation for challenging pedicles. This was a two-part retrospective review of 573 AIS patients that underwent PSF.Part I: 304 were operated in FOFA. 63 patients were operated on with solely CT-based navigation technology (CAS Group). 206 patients were in T&T. Perioperative outcomes were compared.Part II: 206 T&T patients were compared to 326 AIS patients from the NSQIP database that were operated on using computer-assisted navigation (CAN). Operative time and 30-day complications were compared.All data is presented as medians, IQR, frequencies, and percents. Fisher's Exact, Chi-squared, Kruskal-Wallis, and Wilcoxon rank-sum tests were used. FOFA radiation dose was 2.3mGy and radiation time was 20.4 seconds compared to 22.2mGy and 21.6 seconds for CAS, and 15.0mGy and 18.6 seconds for T&T (P<0.001, P<0.001). Operative time was shorter for the T&T patients when compared to FOFA and CAS (P<0.001).Part II: T&T had an operative time of 233.0 minutes compared to 323.0 minutes for CAN (P<0.001). T&T optimizes screw accuracy while reducing the increased radiation burden and operative time associated with CAS. The T&T approach incorporates CT-based navigation technology as confirmation, while maintaining surgeon's skill.

The Classification of Axial Deformity in Patients with Basilar Invagination.

To summarize the variation types of the axis in patients with basilar invagination (BI), then propose a classification scheme of the axis deformity. From December 2013 to September 2020, 92 patients (male 42, female 50) who were diagnosed with BI were studied retrospectively. Based on the imaging data of CT, the width and height of the axis pedicle and the sagittal diameter of the lateral mass were measured in each patient. According to the development of axis pedicle and lateral mass, the types of axis variation were summarized, and then the classification scheme of axis deformity was put forward. All cases were analyzed and axis deformities were divided into four types. Type I: the axis is basically normal (53 cases, 57.6%). Type II: axis lateral mass is dysplasia (eight cases, 8.7%), which includes two subtypes: type IIA, the axis unilateral lateral mass is dysplasia (three cases); type IIB, the axis bilateral lateral masses are all dysplasia (five cases). Type III: axis pedicle is dysplasia (11 cases, 12%), which is subdivided into two subtypes: type IIIA, the axis unilateral pedicle is dysplasia (six cases); type IIIB, the axis bilateral pedicles are all dysplasia (five cases). Type IV: axis pedicle and lateral mass are all dysplasia (20 cases, 21.7%), this type contains the following four subtypes: type IVA, the unilateral axis pedicle and unilateral lateral mass (contralateral or ipsilateral) are all hypoplasia (four cases); type IVB, the unilateral axis pedicle and bilateral lateral masses are all hypoplasia (five cases); type IVC, the bilateral axis pedicles and unilateral lateral mass are all dysplasia (seven cases); type IVD, the bilateral axis pedicles and bilateral lateral masses are all dysplasia (four cases). The left and right abnormal lateral mass sagittal diameter (Type II) was (7.23 ± 1.39) mm and (5.96 ± 1.37) mm, respectively, the left and right abnormal pedicle width (Type III) was (2.61 ± 1.01) mm and (3.23 ± 0.66) mm, respectively, left and right abnormal pedicle height (Type III) was (5.43 ± 2.19) mm and (4.92 ± 1.76) mm, respectively. Moreover, the classification scheme has good repeatability and credibility. The classification about axis deformity could provide personalized guidance for axis screw placement in the BI and other upper cervical surgery, and axis screw placement errors would be effectively avoided.

Use of computer navigation and robotics in adult spinal deformity

Recent years have seen significant advancements in the implementation of computer-assisted surgery in spine. Enabling technologies like robots and navigation have been refined to compliment the field's shift towards minimally invasive techniques and to fit more seamlessly into the existing workflow. Robotic-surgery and navigation in deformity can be particularly helpful in cases where the severe curves of the spinal column or the abnormal pedicle anatomy make pedicle screw placement challenging with the use of traditional anatomic landmarks. Furthermore, the ability to pre-plan patient specific rods has opened the door for greater precision in rod contouring. Drawbacks of robotic-assisted surgery include the steep upfront cost, the need for additional staff and training and the lack of tactile feedback. This review will discuss the current state of navigation and robotics, with a specific focus on their applications to deformity surgery.

P47. TNT: Using technique ‘n’ technology to improve safety and outcomes in AIS

<h3>BACKGROUND CONTEXT</h3> Pedicle screw insertion in scoliosis is challenging due to the 3-dimensional deformity and abnormal pedicle morphology. Free hand or fluoroscopic guidance is frequently utilized. Technological advancements have led to more adaptation of computer assisted screw insertion. These involve changing the technique from a ‘tactile feedback' to ‘screen-based guidance'. While improvement in screw accuracy has been documented, an increase in surgical time with increased possibility of blood loss, and risk of infection can occur. Additionally, increased radiation exposure, especially with a subsequent second spin for confirmation after navigation is also a concern in pediatric population. <h3>PURPOSE</h3> This study aims to evaluate the surgical outcomes of a free hand screw insertion followed by intraop CT confirmation and compare to free hand with fluoroscopy and traditional computer assisted approaches. <h3>STUDY DESIGN/SETTING</h3> Retrospective review. <h3>PATIENT SAMPLE</h3> Retrospective chart review of 289 AIS patients between 2015 and 2020 from a single institution and 356 AIS from NSQIP 2012-2018 database undergoing posterior spinal fusion. <h3>OUTCOME MEASURES</h3> Radiographic outcomes and surgical outcomes including radiation dose, blood loss, operative time and 30-day complication rates. <h3>METHODS</h3> Part I: 152 patients were operated using the freehand technique ‘n' AIRO technology approach (TNT group); 137 were operated using freehand anatomic and fluoroscopy (Fluoro Group). Radiographic measurements, and clinical outcomes including radiation dose, blood loss, operative time and 30-day complications were compared. Part II: 152 TNT patients were compared to 356 AIS patients from the NSQIP database that were operated on using computer-assisted navigation between 2012 and 2018 (Navigation Group). Operative time, blood loss and 30-day complications were compared. All data was presented as mean and frequencies where appropriate. Fisher's Exact and Kruskal-Wallis tests were used for statistical analysis. <h3>RESULTS</h3> Part I: Average radiation dose for TNT patients was 8.3 mGy compared to 3.5 mGy for the fluoro group (p < 0.001). Average radiation time was 12.6 seconds for the TNT group versus 29.8 seconds for Fluoro (p < 0.001). Operative time was significantly shorter for the TNT patients with an average of 236.6 minutes versus 308.8 minutes (p < 0.001). TNT patients had significantly less blood loss than fluoro patients (444 cc vs 625 cc, p < 0.001). 17 (11.1%) of TNT patients required transfusion compared to 24 (17.5%) Fluoro patients (p < 0.001). Two (2.3%) patients in the TNT group returned within 30-days for superior mesenteric artery syndrome. 5 (3.6%) Fluoro patients returned within 30 days, four for surgical site infections requiring irrigation and debridement, and one patient returned for deep vein thrombosis. Part II: TNT Group had a mean operative time of 236.6 minutes compared to 352 for the Navigation group (p < 0.001). 73.6% of Navigation patients were transfused versus 9.2% of TNT patients (p < 0.001). Navigation patients had significantly more 30-day complication than TNT patients (p < 0.001). Most Navigation returns were deep wound infection, sepsis and reoperation. In contrast, TNT patients only had two cases of superior mesenteric artery syndrome. <h3>CONCLUSIONS</h3> As novel technology allows for better anatomic bone visualization, surgeons should implement these innovations into their technique accordingly, while maintaining surgical control. This technique and technology approach allows for adopting technology into surgical approach rather than restructuring the surgical approach. This happy medium helps with screw accuracy without prolonging surgical time, blood loss and associated complications and has superior surgical outcomes compared to both traditional fluoroscopy and computer assisted approaches. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

Morphological Differences Between the Pedicles in Nondystrophic Scoliosis Secondary to Neurofibromatosis Type 1 and Those in Adolescent Idiopathic Scoliosis

To compare the pedicle morphology of nondystrophic scoliosis secondary to neurofibromatosis type 1 (ND-NF1) scoliosis secondary to neurofibromatosis type 1 (NF1-S) and adolescent idiopathic scoliosis (AIS) using computed tomography (CT) in a consistent classification system. The transverse pedicle widths of cancellous and cortical channels were measured using preoperative spinal CT images (T1-L5) and then classified as having type A-E pedicles; type B, C, D, and E pedicles were regarded as abnormal. A subset of these patients, a postoperative CT was performed to evaluate the accuracy of pedicle screw placement. According to the perforation of the medial or lateral pedicle walls by the pedicle screw, the placement of screw was classified by a grade ranging from 0 to 3, and grades 2 and 3 were regarded as misplacement. In total, 3230 pedicles were measured and classified, and the incidence rate of abnormal pedicles in the ND-NF1 group was significantly greater than that of the AIS group (65.9% vs. 61.4%, P= 0.03). The misplacement rate in the ND-NF1 group was significantly greater than that in the AIS group (12.2% vs. 7.4%; P=0.01), and in terms of the corresponding 1100 pedicles, the incidence rate of abnormal pedicles in the ND-NF1 group was higher than that in the AIS group (71.7% vs. 64.9%; P= 0.02). The incidence rate of abnormal pedicles in patients with ND-NF1 is significantly greater than that of patients with AIS, and it may the reason for the higher misplacement rate of pedicle screws in patients with ND-NF1.

End Vertebra Versus Apical Vertebra: Where Are We More Likely to Misplace in Spine Deformity?

Pedicle screws placement remains technically demanding. The thoracic curve apex is considerably difficult due to its unique morphology and severe rotation. In comparison the upper end vertebrae have smaller pedicles and limited soft tissue exposure. This study seeks to evaluate the likelihood of screw misplacement at the end vertebra and apex. A retrospective review of preoperative and postoperative computed tomographic (CT) scans of spinal deformity patients who underwent posterior spinal fusion with pedicle screw constructs between 2004 and 2011 was performed. Pedicles located at the upper instrumented vertebra (UIV) and lower instrumented vertebra (LIV), and the major and minor apices were evaluated. Pedicle morphology was studied on preoperative CT and screw placement on postoperative CT. In total, 188 patients met the inclusion criteria, 172 had preoperative CT scans and 133 had postoperative CT scans. The UIV had a significantly lower percentage of normal pedicles (type A) compared with apex major, apex minor, or LIV (59.1% vs. 76.1% vs. 77.3% vs. 98.7%; P<0.001). UIV had significantly the lowest percentage of normal normally placed screws compared with LIV, apex major, or apex minor (69.4% vs. 97.3% vs. 87.6% vs. 92.1%; P<0.001). In a logistic regression adjusted for preoperative Cobb angles, UIV was more likely to have screws misplaced (odds ratio =7.56; 95% confidence interval, 4.01-14.30; P<0.001) and abnormal pedicles (odds ratio=2.81; 95% confidence interval, 1.52-5.19; P=0.001) compared with any other location studied. In abnormal pedicles, 41 (39.8%) of the 103 UIV screws were misplaced, whereas 10 (16.4%) of the 61 apex major, apex minor, or LIV screws were misplaced (P=0.007). The UIV presents more of a risk for pedicle screw misplacement and abnormal morphology when compared with LIV and apical vertebra. We believe these findings can aid in the surgeon's preoperative and intraoperative management to ensure increased success in accurate and safe pedicle screw placement. Level III.

The Prevalence and Distribution of Vertebral Pedicles in Adolescent Idiopathic Scoliosis in Chinese people: A Computed Tomography–Based Study of 2958 Vertebral Pedicles

To explore the prevalence and distribution of abnormal vertebral pedicles in adolescent idiopathic scoliosis (AIS) in Chinese people. We retrospectively reviewed AIS patients at a single institution between 2011 and 2017. Transverse pedicle widths from T1 to L5 were measured carefully using computed tomography, including cancellous and cortical channels. Pedicle morphology was classified as: type A, a cancellous channel larger than 4 mm; type B, a cancellous channel measuring 2-4 mm; type C, a cancellous channel smaller than 2 mm with an entirely cortical channel of 2 mm or greater; or type D, a cortical channel smaller than 2 mm. Types B, C, and D were defined as abnormal. Prevalence and distribution of abnormal pedicles were assessed. Eighty-seven patients with AIS, with a total of 2958 vertebral pedicles, were carefully measured and classified. The total prevalence of abnormal vertebral pedicles was as high as 65%, with type B comprising 40%, type C comprising 23%, and type D comprising 2%. Pedicles were located between T2 and T10 in 84% of type C and 91% of type D cases. Female sex, proximal thoracic location, major curve greater than 70 degrees, and concave pedicle may be risk factors for type C and D pedicles. There is a significantly high prevalence of abnormal pedicles in AIS in Chinese people, with a total prevalence of 65%. Female sex, proximal thoracic location, major curve greater than 70 degrees, and concave pedicle may be risk factors for type C and D pedicles.

Safety of Pedicle Screws in Adolescent Idiopathic Scoliosis Surgery.

To review existing publications on the safety of pedicle screw insertions in adolescent idiopathic scoliosis (AIS). Despite having increased risk for neurological and visceral injuries, the use of pedicle screws have led to increased correction rates in scoliosis surgery. A review was performed on topics pertinent to pedicle screw insertion in AIS, which included pedicle morphometry in AIS, structures at risk during pedicle screw insertion, and accuracy and safety of various pedicle screw insertion techniques. The importance of computer navigation and future research regarding pedicle screw placement in AIS were also briefly reviewed. Many authors have reported abnormal pedicle anatomy in AIS. Injury to the neural structures was highest over the apical region, whereas aortic injury was the highest at T5 and T10. In the proximal thoracic spine, the esophagus could be injured even with screws as short as 25 mm. Overall pedicle perforation rates for perforations >0 and >2 mm (assessed by computed tomography) ranged from 6.4% to 65.0% and 3.7% to 29.9%, respectively. The critical pedicle perforation (>2 mm excluding lateral thoracic) and anterior perforation (>0 mm) rates was reported to range from 1.5% to 14.5% and 0.0% to 16.1%, respectively. Pedicle perforation rates were lower with the use of computer navigation. The incidence of neurological adverse events after scoliosis surgery was 0.06%–1.9%. Aortic injury has only been observed in case reports. According to the available literature, pedicle screw insertion in AIS is considered safe with low rates of clinical adverse events. Moreover, the use of navigation technology has been shown to reduce pedicle perforation rates.

Prevalence, Distribution, and Surgical Relevance of Abnormal Pedicles in Spines with Adolescent Idiopathic Scoliosis vs. No Deformity: A CT-Based Study.

A thorough understanding of pedicle morphology is necessary for pedicle screw placement. Previous studies classifying pedicle morphology, to our knowledge, have neither discussed the range of abnormal morphology nor correlated patient or curve characteristics with abnormal morphology to identify at-risk pedicles. With the use of computed tomography (CT) images, we analyzed a total of 6116 pedicles from ninety-five patients without spinal deformity (forty-two females and fifty-three males) and ninety-one patients with adolescent idiopathic scoliosis (AIS) (sixty-eight females and twenty-three males). Pedicle morphology was classified as: Type A, a cancellous channel of >4 mm; Type B, a cancellous channel of 2 to 4 mm; Type C, a cortical channel of ≥2 mm; or Type D, a cortical or cancellous channel of <2 mm. Types B, C, and D were defined as abnormal. Patient demographic data and pedicle distribution were assessed for prevalence and likelihood of abnormal pedicle morphology. Postoperative CT images from fifty-nine patients with AIS were used to assess screw placement. There was a significantly higher rate of abnormal pedicles in patients with AIS (p = 0.001). More abnormal pedicles were located in the thoracic spine compared with the lumbar spine both in patients without deformity (13.3% versus 2.0%) and patients with AIS (31.9% versus 2.4%). Significantly more abnormal pedicles were located on the concavity (p < 0.001), within the periapical region (p = 0.02), and on the apex of the curve (p = 0.03). Three times as many pedicle screws were misplaced in abnormal pedicles compared with normal pedicles (21% versus 7%). Our study found a significantly higher prevalence of abnormal pedicles in the patients with AIS. Of the abnormal pedicles in these patients, most were in the thoracic spine, on the concave side, and in the periapical and apical regions. Knowledge of abnormal pedicles may enable surgeons to anticipate and plan for difficult screw placement and further decrease risk to the patient.

Incidence, Distribution, and Surgical Relevance of Abnormal Pedicles in Normal and Deformed Spines: A CT-Based Study of 6256 Pedicles

Incidence, Distribution, and Surgical Relevance of Abnormal Pedicles in Normal and Deformed Spines: A CT-Based Study of 6256 Pedicles

ABNORMAL ANTLERS AND PEDICLES ON ROCKY MOUNTAIN ELK IN NORTHERN ARIZONA

Abstract Rocky Mountain elk (Cervus elaphus nelsoni) bearing malformed antlers have been observed in northern Arizona during the last 10 years. We collected measurements from 28 skulls of bulls bearing abnormal antlers from the Hualapai Indian Reservation in northwestern Arizona. Most abnormalities were unilateral. Deformed antlers were smaller and had fewer points than normal ones, and originated from deformed pedicles. The abnormal pedicles tended to be larger, and varied in orientation and location relative to normal pedicles. Some males lacked pedicles on 1 side, and the deformed antlers originated directly from the frontal bones. Similar antler and pedicle abnormalities have been documented in other elk populations in northern Arizona. The appearance of the abnormal pedicles was consistent with fracture and subsequent repair of the bones. Such damage might be incurred during sparring among males, and multiple factors might predispose the pedicles to injury.

Benign osteoblastoma of the spine in childhood

Osteoblastoma of the spine is a rare but important cause of back pain in children. Ten children with this tumor were treated at the Alberta Children's or Foothills Hospital in Calgary, Alberta, between 1974 and 1986. There were seven boys and three girls; the age at diagnosis ranged from 2 to 16 years (average 11 years). In nine patients the tumor involved the posterior vertebral elements. One of the cervical lesions was in the vertebral body. Three patients had tumor in the extradural space. The commonest symptom was pain in the back and neck. Bone scans were positive in all patients, and computerized tomography scans were abnormal in the eight patients who had this imaging performed. Nine children were treated with laminectomy and removal of the abnormal pedicle and facet. Two patients required two operations each because of incomplete tumor excision at the first operation; in these, subsequent surgery gave complete relief of symptoms and radiographic studies showed no further tumor. In three other patients, tumor removal was incomplete, and one patient received postoperative radiation therapy. Bone grafts were placed in four patients. The diagnosis of benign osteoblastoma was confirmed histologically in nine patients. The outcome was good in all cases, with excellent pain relief. The follow-up period has varied from 8 to 153 months (average 66 months) and there have been no recurrences. Based on this experience, complete excision of spinal osteoblastomas is recommended whenever possible. However, a satisfactory outcome may be achieved following incomplete excision and bone grafting.