Screw Revision Research Articles

Image-Guided Cervical Pedicle Screw Fixation: Implant Precision and Complications in 67 Consecutive Patients

Introduction Cervical pedicle screws (CPS) are an alternative technique to lateral mass fixation. We present our experience of 67 patients who underwent image-guided CPS instrumentation, either exclusively or as part of a construct. Implant precision, as measured by the orthogonal view evaluation method (OVEM), and complications are reported in all patients. Materials and Methods Retrospective chart review of a single institution experience of 67 consecutive patients, with 356 screws placed ( Table 1 ), including 232 subaxial pedicle screws. Implant precision was measured using OVEM (unpublished data). This allows multiple orthogonal views along the long axis of the screw through the bone target on CT multiplanar images. Grade I: no bone breach, GrIa: screw thread breach, GrII: internal screw diameter breach, and GrIII: neurovascular injury. Complications including those related to implant placement are presented in Table 2 . Results There were two implant-related complications. One, when a lateral mass screw was pulled out and replaced with a CPS. The other was because of a post CPS placement radiculopathy, which resolved on screw revision. There were three postoperative wound infections (4.5%) and five patients with postoperative pneumonia (7.5%). [Table: see text][Table: see text] Conclusion CPS is an alternative screw implantation technique which appears to be safe and effective with two screw revisions necessary (3% patients), with no neurovascular injury. There was a 23% navigational “failure” using OVEM criteria (GrII), which may be attributed to strict precision criteria. CPS may be useful when high biomechanical loads are anticipated, where there is poor bone quality or a pedicle fracture.

The Efficacy and Accuracy of Cone Beam CT (O-Arm) Navigation (StealthStation) on Screw Position in Adult Scoliosis Surgery

Introduction Intraoperative CT and navigation systems may provide an opportunity to improve precision and accuracy of pedicle screw placement, and in so doing, improve patient outcomes. Adult spinal deformity provides unique anatomical challenges potentially amenable to spinal navigation. Our study aimed to examine the efficacy and safety of intraoperative cone beam CT navigation for pedicle screw placement in complex spinal deformity cases. Material and Methods We identified all patients treated at our institution with spinal fusion for the primary diagnosis of major adult deformity between January 2008 and December 2012 in whom O-arm and StealthStation navigation was used (NAV). A historic control cohort (non-NAV) was matched based on age, number of levels, curve type and size, and previous fusion. The number and timing (intraoperative, early symptomatic postoperative, late symptomatic postoperative, and incidental) of screw malposition and the need for revision screw placement were recorded. All patients had a minimum follow-up of 1 year. Any screw with pedicle breach greater than 0 mm was recorded as misplaced. The direction and anatomical level of misplaced screws were also determined. Quantitative statistical analysis compared screw placement between NAV and non-NAV cases. Results A total of 56 patients met the inclusion criteria in both cohorts (112 patients). The mean number of screws placed in each group was not significantly different (17.29 in NAV and 17.71 in non-NAV, p = 0.75). Thirty-eight (34%) patients in the non-NAV group had misplaced screws compared with 21 (19%) in the NAV group ( p = 0.002). The detection of incidental screw malposition was significantly higher in the non-NAV cases (44.6 vs. 23.2%, p < 0.05) and the need for intraoperative screw revision favored navigation ( p < 0.03). Six cervical screws, 16 cervicothoracic, 90 thoracic, and 112 lumbar screws were placed. Early postoperative screw revision rates approached significance ( p < 0.06) favoring navigation. The number of adverse events and length of stay (mean 17 vs. 20.4 days in NAV and non-NAV groups, respectively) were not significantly different. The mean number of postoperative CT scans was significantly fewer in the NAV group (9 vs. 22 in non-NAV group, p = 0.004), while mean OR time was statistically different between groups (492 minutes in the NAV group vs. 408 minutes in the non-NAV, p = 0.002). Conclusion Our results demonstrate that intraoperative CT-guided navigation provides an equally safe and more accurate and precise tool for pedicle screw placement than traditional techniques in adult spinal deformity surgery. There were more intraoperative screws adjusted and fewer postoperative screws revised with NAV. Far fewer patients required postoperative CT examination with the use of NAV.

Simultaneous Lateral Interbody Fusion and Posterior Percutaneous Instrumentation: Early Experience and Technical Considerations.

Lumbar fusion surgery involving lateral lumbar interbody graft insertion with posterior instrumentation is traditionally performed in two stages requiring repositioning. We describe a novel technique to complete the circumferential procedure simultaneously without patient repositioning. Twenty patients diagnosed with worsening back pain with/without radiculopathy who failed exhaustive conservative management were retrospectively reviewed. Ten patients with both procedures simultaneously from a single lateral approach and 10 control patients with lateral lumbar interbody fusion followed by repositioning and posterior percutaneous instrumentation were analyzed. Pars fractures, mobile grade 2 spondylolisthesis, and severe one-level degenerative disk disease were matched between the two groups. In the simultaneous group, avoiding repositioning leads to lower mean operative times: 130 minutes (versus control 190 minutes; p = 0.009) and lower intraoperative blood loss: 108 mL (versus 93 mL; NS). Nonrepositioned patients were hospitalized for an average of 4.1 days (versus 3.8 days; NS). There was one complication in the control group requiring screw revision. Lateral interbody fusion and percutaneous posterior instrumentation are both readily accomplished in a single lateral decubitus position. In select patients with adequately sized pedicles, performing simultaneous procedures decreases operative time over sequential repositioning. Patient outcomes were excellent in the simultaneous group and comparable to procedures done sequentially.

Learning curve of 3D fluoroscopy image–guided pedicle screw placement in the thoracolumbar spine

Background contextDuring the past decade, a disproportionate increase of spinal fusion procedures has been observed. Along with this trend, image-guided spine surgery has been experiencing a renaissance in the recent years. A wide range of different navigation systems are available on the market today. However, only few published studies assess the learning curves concerning these new spinal navigation techniques. So far, a study on the learning curve for intraoperative three-dimensional fluoroscopy (3DFL)–navigated pedicle screw (PS) placement is still lacking. PurposeThe purpose of the study was to analyze the learning curve for 3DFL-navigated thoracolumbar PS placement. Study design/settingThe study design included a prospective case series. Patient sampleA cohort of 145 patients were recruited from January 2011 to June 2012. Outcome measuresThe outcome measures were duration of intraoperative 3D scans, PS placement, PS accuracy on postoperative computed tomography (CT) scans, and PS-related revisions and complications. MethodsFrom the introduction of spinal navigation to our department in January 2011 until June 2012, the learning curve for the duration of intraoperative 3D scan acquisition (navigation or control scan) and placement time per screw, intraoperative screw revisions, screw-related complications, revision surgeries, and PS accuracy on postoperative CT scans were assessed in 145 patients undergoing dorsal navigated instrumentation for 928 PS (736 lumbosacral and 192 thoracic). The observed time span was divided into four intervals. Results of the second, third, and last periods were compared with the first (reference) period, respectively. ResultsThe mean navigation 3D scan time decreased (first and fourth periods) from 15.4±7.8 (range, 4–40) to 8.4±3.3 (3–15) minutes (p<.001). The mean control 3D scan time (after PS placement) decreased from 11.2±4.8 (5–25) to 6.6±3.0 (3–15) minutes (p<.001). The mean PS insertion time decreased from 5.3±2.5 (1–15) to 3.2±2.3 (1–17) minutes (p<.001). The mean proportion of correctly positioned PS (all 928) according to the Gertzbein and Robbins classification grades A and B increased initially from 83.1% (first period) to 95.1% (second period, p=.001), 96.4% (third period, p=.002), and 92.4% (fourth period, p=.049). No learning effect was found with respect to intraoperative screw revisions. There was one revision surgery. ConclusionsWe could demonstrate significant learning effects for 3DFL-navigated PS placement with regard to intraoperative 3D scan acquisition, PS placement time, and PS accuracy.

A Comparison of Complications of Total Wrist Fusion and Silastic Arthroplasty

The use of the Swanson silastic arthroplasty for the treatment of the rheumatoid hand has been shown to correct deformities and improve function. Silastic arthroplasty has a tendency to fracture requiring revision, while wrist fusion is thought to be a more durable solution. We conducted a retrospective case note analysis of all patients undergoing wrist arthroplasty or wrist fusion for clinical follow-up. Radiographic imaging was reviewed. Patient records on the combined GP/Hospital database were reviewed for the purpose of community follow-up. In the cohort of patients who underwent silastic arthroplasty, the indications for surgery were 14 rheumatoid arthritis, 2 psoriatic arthritis, 2 juvenile arthritis, and 3 osteoarthritis. Of the 21 patients, 17 were older than 65 years of age. There were 3 reported complications: a postoperative wound infection that required debridement, a complex regional pain syndrome, and an ongoing symptoms of pain requiring debridement of the distal radius. There were no implant fractures at last radiographic review. The 5-year survivorship was 100% with reoperation as the end point with 2 implants lasting up to 15 years. A total of 38 patients underwent a wrist fusion, with a mean age of 52 years, with 6 patients older than 65 years of age. In all, 17 were undertaken for osteoarthritis, with 1 case of avascular necrosis of the capitate in a patient with calcinosis, Raynaud phenomenon, esophageal dysmotility, sclerodactyly, and telangiectasia (CREST) syndrome. Eleven patients reported time off work as a direct result of their symptoms. Postoperative complications include hematoma, complex regional pain syndrome, distal radial ulnar joint pain requiring Darrach procedure in 4 patients, screw revision following prominence, and 4 cases where the metal ware was removed. All fusions went onto unite. Survivorship at 5 years was 91% with reoperation as the end point. This small case series shows that for this highly selected group of patients with an inflammatory arthropathy, silastic arthroplasty remains a viable option. For elderly patients having rheumatoid with low demand, this treatment has a lower reoperative rate at 5 years and therefore may often be the final treatment they require.

Safety and efficacy of pedicle screw placement using intraoperative computed tomography: consecutive series of 1148 pedicle screws.

A number of imaging techniques have been introduced to minimize the risk of pedicle screw placement. Intraoperative CT has been recently introduced to assist in spinal instrumentation. The aim of this study was to study the effectiveness of intraoperative CT in enhancing the safety and accuracy of pedicle screw placement. The authors included all cases from December 2009 through July 2012 in which intraoperative CT scanning was used to confirm pedicle screw placement. A total of 203 patients met the inclusion criteria. Of 1148 screws, 103 screws (8.97%) were revised intraoperatively in 72 patients (35.5%): 14 (18.42%) were revised in the cervical spine (C-2 or C-7), 25 (7.25%) in the thoracic spine, and 64 (8.80%) in the lumbar spine. Compared with screws in the thoracic and lumbar regions, pedicle screws placed in the cervical region were statistically more likely to be revised (p = 0.0061). Two patients (0.99%) required reoperations due to undetected misplacement of pedicle screws. The authors describe one of the first North American experiences using intraoperative CT scanning to confirm the placement of pedicle screws. Compared with a similar cohort of patients from their institution who had pedicle screws inserted via the free-hand technique with postoperative CT, the authors found that the intraoperative CT lowers the threshold for pedicle screw revision, resulting in a statistically higher rate of screw revision in the thoracic and lumbar spine (p < 0.0001). During their 2.5-year experience with the intraoperative CT, the authors did not find a reduction in rates of reoperation for misplaced pedicle screws.

The "slide technique": an improvement on the "funnel technique" for safe pedicle screw placement in the thoracic spine.

Technical note. To report and describe a new free-hand technique for pedicle screw placement in the thoracic spine especially in severe deformities. Because of distortion of anatomic landmarks scoliosis, this free-hand placement technique based on pedicle access through the decancelled transverse process is a safe procedure. Transverse process is widely exposed and its posterior cortex is decorticated. The cancellous bone content of the transverse process is completely removed using a small curette. Bone wax is applied to avoid local bleeding and then the decancelled transverse process is inspected. The entry of the pedicle is then easily identified by the presence of remaining cancellous bone. A pedicular probe is then inserted and gently advanced. During pedicle probe insertion, the cortex of the anterior aspect of transverse process and the lateral margin of the pedicle act as a "slide" to permit safe insertion of the instrument. In our experience, no patient required additional procedures for screw revision, and no neurologic deficit occurred stemming from malpositioning of pedicle screws. The key point of the "slide technique" is to use the cortex of the anterior aspect of transverse process and the lateral margin of the pedicle as a "slide" to permit correct probe positioning during pedicle probe insertion. This technique is very close to the "funnel technique". The "funnel" and then the "slide" technique are mostly useful in complex spinal deformities as in neuromuscular patients. The "slide technique" is a safe, effective and cost-effective technique for pedicle screw placement in the thoracic spine especially in severe deformities. IV.

Thoracolumbar instrumentation with CT-guided navigation (O-arm) in 270 consecutive patients: accuracy rates and lessons learned

Thoracolumbar instrumentation has experienced a dramatic increase in utilization over the last 2 decades. However, pedicle screw fixation remains a challenging undertaking, with suboptimal placement contributing to postoperative pain, neurological deficit, vascular complications, and return to the operating suite. Image-guided spinal surgery has substantially improved the accuracy rates for these procedures. However, it is not without technical challenges and a learning curve for novice operators. The authors present their experience with the O-arm intraoperative imaging system and share the lessons they learned over nearly 5 years. The authors performed a retrospective chart review of 270 consecutive patients who underwent thoracolumbar pedicle screw fixation utilizing the O-arm imaging system in conjunction with StealthStation navigation between April 2009 and September 2013 at a single tertiary care center; 266 of the patients underwent CT scanning on postoperative Day 1 to evaluate hardware placement. The CT scans were interpreted prospectively by 3 neuroradiologists as part of standard work flow and retrospectively by 2 neurosurgeons and a senior resident. Pedicle screws were evaluated for breaches according to the 3-tier classification proposed by Mirza et al. Of 270 patients, 266 (98.5%) were included in the final analysis based on the presence of a postoperative CT scan. Overall, 1651 pedicle screws were placed in 266 patients and yielded a 5.3% breach rate; 213 thoracic and 1438 lumbosacral pedicle screws were inserted with 6.6% and 5.1% breach rates, respectively. Of the 87 suboptimally placed screws, there were 13 Grade 1, 16 Grade 2, and 12 Grade 3 misses as well as 46 anterolateral or "tip-out" perforations at L-5. Four patients (1.5%) required a return to the operating room for pedicle screw revision, 2 of whom experienced transient radicular symptoms and 2 remained asymptomatic. Interestingly, the pedicle breach rate was higher than anticipated at 13.21% for the 30 patients over the initial 6-month period with the O-arm. After certain modifications to the authors' technique, the subsequent 30 patients experienced a statistically significant decrease in breach rate at 5.6% (p = 0.014). Image-guided spinal surgery can be a great option in the operating room and provides high pedicle screw accuracy rates. With numerous systems commercially available, it is important to develop a systematic approach regardless of the technology in question. There is a learning curve for surgeons unfamiliar with image guidance that should be recognized and appreciated when transitioning to navigation-assisted spinal surgery. In fact, the authors' experience with a large patient cohort suggests that this learning curve may be more significant than previously reported.

Intraoperative three-dimensional fluoroscopy after transpedicular positioning of Kirschner-wire versus conventional intraoperative biplanar fluoroscopic control: A retrospective study of 345 patients and 1880 pedicle screws.

Study Design:Retrospective study.Objective:The aim was to find out whether intraoperative three-dimensional imaging after transpedicular positioning of Kirschner wire (K-wire) in lumbar and thoracic posterior instrumentation procedures is of benefit to the patients and if this technique is accurately enough to make a postoperative screw position control through computer tomography (CT) dispensable.Patients and Methods:Lumbar and thoracic posterior instrumentation procedures conducted at our department between 2002 and 2012 were retrospectively reviewed. The patients were divided into two groups: group A, including patients who underwent intraoperative three-dimensional scan after transpedicular positioning of the K-wire and group B, including patients who underwent only intraoperative biplanar fluoroscopy. An early postoperative CT of the instrumented section was done in all cases to assess the screw position. The rate of immediate intraoperative correction of the K-wires in cases of mal-positioning, as well as the rate of postoperative screw revisions, was measured.Results:In general, 345 patients (1880 screws) were reviewed and divided into two groups; group A with 225 patients (1218 screws) and group B with 120 patients (662 screws). One patient (0.44%) (one screw [0.082%]) of group A underwent postoperative screw correction while screw revisions were necessary in 14 patients (11.7%) (28 screws [4.2%]) of group B. Twenty-three patients (10.2%) (28 K-wires [2.3%]) of group A underwent intraoperative correction due to primary intraoperative detected K-wire mal-position. None of the corrected K-wires resulted in a corresponding neurological deficit.Conclusion:Three-dimensional imaging after transpedicular K-wire positioning leads to solid intraoperative identification of misplaced K-wires prior to screw placement and reduces screw revision rates compared with conventional fluoroscopic control. When no clinical deterioration emerges, a postoperative CT seems to be dispensable using this intraoperative three-dimensional control method.

Intrapelvic migration of the lag screw in intramedullary nailing.

Internal fixation with intramedullary devices has gained popularity for the treatment of intertrochanteric femoral fractures, which are common injuries in the elderly. The most common complications are lag screw cut out from the femoral head and femoral fracture at the distal tip of the nail. We report here a rare complication of postoperative lag screw migration into the pelvis with no trauma. The patient was subsequently treated with lag screw removal and revision surgery with total hip arthroplasty. This case demonstrated that optimal fracture reduction and positioning of the lag screw are the most important surgical steps for decreasing the risk of medial migration of the lag screw. Furthermore, to prevent complications, careful attention should be paid to subsequent steps such as precise insertion of the set screw.

Slipped capital femoral epiphysis in a healthy 5-year-old child: A case report and literature review

Slipped capital femoral epiphysis (SCFE) is an adolescent hip disorder of increasing prevalence, particularly within patients aged younger than 10 years. When present in these younger patients, SCFE is usually associated with metabolic abnormality or endocrinopathy. We present a case of a 5-year-old boy with idiopathic SCFE who underwent staged bilateral pinning in situ using a uniquely modified smooth wire for fixation across the physis. He eventually required bilateral screw revision after outgrowing the initial screws. At follow-up 3 years later, the patient was pain free with satisfactory hardware placement. He will be closely monitored, as he will likely need further surgical revision once he outgrows the second set of fixation screws.

Feasibility of Intraoperative Computed Tomography Navigation System for Pedicle Screw Insertion of the Thoracolumbar Spine

STUDY DESIGN:: A retrospective analysis of feasibility of intraoperative computed tomography (iCT) navigation for pedicle screw insertion of the thoraco-lumbar spine OBJECTIVES:: This study assessed the feasibility of an iCT navigation system by evaluating the screw insertion time, screw revision time, and learning curve of the iCT surgical team in patients who underwent thoraco-lumbar pedicle screw surgery using this navigation system. SUMMARY OF BACKGROUND DATA:: The iCT navigation system has been reported to improve the accuracy and safety of pedicle screw insertion. However, the assessment of the feasibility of spinal instrumentation guided by iCT navigation system is limited. METHODS:: From the time iCT navigation system was set-up to a period covering 16 months, consecutive patients who underwent thoracic or lumbar spinal pedicle screw surgery were enrolled. The screw insertion and screw revision times were estimated using the system's automatic time recording between the intra-operative CT scans. The insertion time per screw of the first 50 patients not requiring screw revision was also analyzed to evaluate the learning curve of the iCT surgical team. RESULTS:: There were 178 patients with a total of 932 pedicle screws. The cortical breach rate was 3.2% and the screw revision rate was 1.4%. The insertion time per screw was 10.2±6.3▒min and the screw revision time was 13.8±9.9▒min. The learning curve of the iCT surgical team for pedicle screw insertion guided by this navigation system was not steep and experience from less than 10 patients was adequate to provide familiarity with this system. CONCLUSION:: The iCT navigation system is clinically feasible for thoraco-lumbar pedicle screw surgery. It provides high-level safety and accuracy, as well as ease of screw revision when required.

Yes, We CAN!

During the past decade, a disproportionate increase of spinal fusion procedures has been observed. Along with this trend, image-guided spine surgery has been experiencing a renaissance in the recent years. A wide range of different navigation systems are available on the market today. However, only few published studies assess the learning curves concerning these new spinal navigation techniques. So far, a study on the learning curve for intraoperative three-dimensional fluoroscopy (3DFL)–navigated pedicle screw (PS) placement is still lacking.The purpose of the study was to analyze the learning curve for 3DFL-navigated thoracolumbar PS placement.The study design included a prospective case series.A cohort of 145 patients were recruited from January 2011 to June 2012.The outcome measures were duration of intraoperative 3D scans, PS placement, PS accuracy on postoperative computed tomography (CT) scans, and PS-related revisions and complications.From the introduction of spinal navigation to our department in January 2011 until June 2012, the learning curve for the duration of intraoperative 3D scan acquisition (navigation or control scan) and placement time per screw, intraoperative screw revisions, screw-related complications, revision surgeries, and PS accuracy on postoperative CT scans were assessed in 145 patients undergoing dorsal navigated instrumentation for 928 PS (736 lumbosacral and 192 thoracic). The observed time span was divided into four intervals. Results of the second, third, and last periods were compared with the first (reference) period, respectively.The mean navigation 3D scan time decreased (first and fourth periods) from 15.4±7.8 (range, 4–40) to 8.4±3.3 (3–15) minutes (p<.001). The mean control 3D scan time (after PS placement) decreased from 11.2±4.8 (5–25) to 6.6±3.0 (3–15) minutes (p<.001). The mean PS insertion time decreased from 5.3±2.5 (1–15) to 3.2±2.3 (1–17) minutes (p<.001). The mean proportion of correctly positioned PS (all 928) according to the Gertzbein and Robbins classification grades A and B increased initially from 83.1% (first period) to 95.1% (second period, p=.001), 96.4% (third period, p=.002), and 92.4% (fourth period, p=.049). No learning effect was found with respect to intraoperative screw revisions. There was one revision surgery.We could demonstrate significant learning effects for 3DFL-navigated PS placement with regard to intraoperative 3D scan acquisition, PS placement time, and PS accuracy.

The Accuracy of Navigation and 3D Image-Guided Placement for the Placement of Pedicle Screws in Congenital Spine Deformity

Treatment of congenital spine deformity has high surgical risk due to abnormal anatomy and dysmorphic pedicles. We hypothesized that an image-guided navigation system would result in a low rate of screw revision due to malposition. From 2007 to 2010, 142 screws were placed in 14 consecutive patients with congenital spine deformity using an intraoperative computer tomography (CT) (O-arm) and image-guided navigation system (Stealth). Mean age was 8.8 years (range, 1 to 18 y). Deformities included scoliosis (12), kyphosis (1), and spinal dysgenesis (1). Screws were placed from T2 to S1. An intraoperative CT verified screw position. Need for intraoperative screw revision is the primary outcome measure. Of the 142 screws placed, 1 required revision intraoperatively due to malposition (99.3% screw accuracy rate). The screw was at L3 and was successfully redirected. There were no complications due to screw malposition. This navigated congenital screw accuracy rate (99.3%) is higher than the 94.9% accuracy rate reported for non-navigated screws in all children undergoing pedicle screw fixation in a recent systematic literature review and higher than the reported 96.4% accuracy rate for navigated pedicle screws in children. Kosmopoulos and colleagues found a lower accuracy rate (86.6%) in adult non-navigated screws (P<0.0001) and adult navigated screws (93.7%). Of note, 9 pedicles were noted on navigation to be absent. Despite the goal of bilateral screw placement at each fusion level, 31 of 173 pedicles were left unfilled due to technical impossibility based on intraoperative CT imaging. This represents an 18% screw dropout rate. CT-guided navigation resulted in the successful placement of 142 pedicle screws in patients with congenital deformity and altered anatomy, which represents a 99.3% screw accuracy rate. This is comparable with the screw accuracy rate of 93.7% reported for adult navigated pedicle screws. Further, navigation prevented attempts of screw placement at levels with absent or impassable pedicles. Image-guided navigation and intraoperative CT are valuable tools for the safe placement of pedicle screws in patients with significant congenital spine deformity and altered anatomy. IV, Case Series.

Analysis of CT-based Navigation System for Pedicle Screw Placement

The incidence of pedicle screw breech varies based on anatomic location, body habitus, surgeon experience, spinal deformity, and surgical technique. Pedicle breeches have been reported to occur in up to 40% of screws. The purpose of this retrospective study was to compare the rates of revision of pedicle screw placement when using intraoperative C-arm vs O-arm (Medtronic, Memphis, Tennessee) assessment of pedicle screws. An economic analysis was also performed based on the estimated cost of pedicle screw revision. Four (1%) of 386 control patients required pedicle screw revision for a breeched pedicle screw not identified with intraoperative C-arm fluoroscopy. In the study group, none of the 331 patients returned to the operating room when O-arm was used to assess pedicle screw placement. Based on the 1% rate of returning to the operating room in the control group, the annual rate of cases nationwide requiring pedicle screw revision would be approximately 2300, with a cost of approximately $40,595,000.These results suggest that the use of intraoperative O-arm can reduce the need for revision of a breeched pedicle screw. This can potentially lead to a major cost savings.

Intraoperative 3-dimensional imaging (O-arm) for assessment of pedicle screw position: Does it prevent unacceptable screw placement?

BackgroundPedicle screws are biomechanically superior over other spinal fixation devices. When improperly positioned, they lose this advantage and put adjacent structures at risk. Accurate placement is therefore critical. Postoperative computed tomography (CT) scans are the imaging gold standard and have shown malposition rates ranging from 2% to 41%. The O-arm (Medtronic Navigation, Louisville, Colorado) is an intraoperative CT scanner that may allow intervention for malpositioned screws while patients are still in the operating room. However, this has not yet been shown in clinical studies. The primary objective of this study was to assess the usefulness of the O-arm for evaluating pedicle screw position by answering the following question: What is the rate of intraoperative pedicle screw revision brought about by O-arm imaging information? A secondary question was also addressed: What is the rate of unacceptable thoracic and lumbar pedicle screw placement as assessed by intraoperative O-arm imaging? MethodsThis is a case series of consecutive patients who have undergone spine surgery for which an intraoperative 3-dimensional (3D) CT scan was used to assess pedicle screw position. The study comprised 602 pedicle screws (235 thoracic and 367 lumbar/sacral) placed in 76 patients, and intraoperative 3D (O-arm) imaging was obtained to assess screw position. Action taken at the time of surgery based on imaging information was noted. An independent review of all scans was also conducted, and all screws were graded as either optimal (no breach), acceptable (breach ≤2 mm), or unacceptable (breach >2 mm). The rate of pedicle screw revision, as detected by intraoperative 3D CT scan, was determined. ResultsOn the basis of 3D imaging information, 17 of 602 screws (2.8%) in 14 of 76 cases (18.4%) were revised at the time of surgery. On independent review of multiplanar images, 11 screws (1.8%) were found to be unacceptable, 32 (5.3%) were acceptable, and 559 (92.9%) were optimal. All unacceptable screws were revised to an optimal or acceptable position, and an additional 6 acceptable screws were revised to an optimal position. Thus, by the end of the cases, none of the 602 pedicle screws in the 76 surgical procedures was in an unacceptable position. ConclusionThe new-generation intraoperative 3D imaging system (O-arm) is a useful tool that allows more accurate assessment of pedicle screw position than plain radiographs or fluoroscopy alone. It prompted intraoperative repositioning of 2.8% of pedicle screws in our series. Most importantly, it allowed identification and revision of all unacceptably placed pedicle screws without the need for reoperation.

Pediatric Pedicle Screw Placement Using Intraoperative Computed Tomography and 3-Dimensional Image-Guided Navigation

A retrospective cohort study reporting the use of intraoperative computed tomography (CT) and image-guided navigation system for the placement of pedicle screws in pediatric compared with adult patients. To evaluate the accuracy of open pedicle screw placement in pediatric patients using intraoperative CT and 3-dimensional (3D) image-guided navigation. Pedicle screws are widely used in children for the correction of spinal deformity. Navigation systems and intraoperative CT are now available as an adjunct to fluoroscopy and anatomic techniques for placing pedicle screws and verifying screw position. From 2007 to 2010, 984 pedicle screws were placed in a consecutive series cohort of 50 pediatric patients for spinal deformity correction with the use of intraoperative CT (O-arm, Medtronic, Inc, Louisville, CO) and a computerized navigation system (Stealth, Medtronic, Inc, Louisville, CO). The primary outcome measure for this study is redirection or removal of screw on the basis of the intraoperative CT imaging. During the study period, 1511 screws were placed in adult patients using the same image guidance system. A total of 984 pedicle screws were implanted using real-time navigation, with a mean of 20 screws per patient (range: 2-34). On the basis of intraoperative CT, 35 screws (3.6%) were revised (27 redirected and 8 removed), representing a 96.4% accuracy rate. No patients returned to the operating room because of screw malposition.Of the 1511 screws placed in adult patients, 28 (1.8%) were revised intraoperatively for malposition on CT imaging, for an overall 98.2% accuracy rate. Screw revision thus was more common in the pediatric population (P = 0.008). However, the pediatric screw accuracy rate is significantly higher than the findings from a recent meta-analysis of predominantly nonnavigated screws in children, reporting a 94.9% accuracy rate (P = 0.03). We report 96.4% accuracy in pediatric pedicle screw placement using intraoperative CT and a 3D navigation system. This is similar to other reports and has better accuracy than a recent meta-analysis of nonnavigated screws in children.

Intraoperative Computed Tomography With Integrated Navigation System in Spinal Stabilizations

STUDY DESIGN.: A prospective interventional case-series study plus a retrospective analysis of historical patients for comparison of data. OBJECTIVE.: To evaluate workflow, feasibility, and clinical outcome of navigated stabilization procedures with data acquisition by intraoperative computed tomography. SUMMARY OF BACKGROUND DATA.: Routine fluoroscopy to assess pedicle screw placement is not consistently reliable. Our hypothesis was that image-guided spinal navigation using an intraoperative CT-scanner can improve the safety and precision of spinal stabilization surgery. METHODS.: CT data of 94 patients (thoracolumbar [n = 66], C1/2 [n = 12], cervicothoracic instability [n = 16]) were acquired after positioning the patient in the final surgical position. A sliding gantry 40-slice CT was used for image acquisition. Data were imported to a frameless infrared-based neuronavigation workstation. Intraoperative CT was obtained to assess the accuracy of instrumentation and, if necessary, the extent of decompression. All patients were clinically evaluated by Odom-criteria after surgery and after 3 months. RESULTS.: Computed accuracy of the navigation system reached <2 mm (0.95 +/- 0.3 mm) in all cases. Additional time necessary for the preoperative image acquisition including data transfer was 14 +/- 5 minutes. The duration of interrupting the surgical process for iCT until resumption of surgery was 9 +/- 2.5 minutes. Control-iCT revealed incorrect screw position >/=2 mm without persistent neurologic or vascular damage in 20/414 screws (4.8%) leading to immediate correction of 10 screws (2.4%). Control-iCT changed the course of surgery in 8 cases (8.5% of all patients). The overall revision rate was 8.5% (4 wound revisions, 2 CSF fistulas, and 2 epidural hematomas). There was no reoperation due to implant malposition. According to Odom-criteria all patients experienced a clinical improvement. A retrospective analysis of 182 patients with navigated thoracolumbar transpedicular stabilizations in the preiCT era revealed an overall revision rate of 10.4% with 4.4% of patients requiring screw revision. CONCLUSION.: Intraoperative CT in combination with neuronavigation provides high accuracy of screw placement and thus safety for patients undergoing spinal stabilization. Reoperations due to implant malpositions could be completely avoided. The system can be installed into a pre-existing operating environment without need for special surgical instruments. The procedure is rapid and easy to perform without restricted access to the patient and-by replacing pre- and postoperative imaging-is not associated with an additional exposure to radiation. Multidisciplinary use increases utilization of the system and thus improves cost-efficiency relation.

Treatment of femoral neck fractures in pediatric patients.

Objective To investigate the therapeutic results of femoral neck fractures in pediatric patients in our center and review the literature. Methods Authors conducted a computerized search of med-ical records to identify all children with femoral neck fractures treated at our institution from January 1986 to December 2007. Records were reviewed to determine injury mechanism, fracture type (Delbet's classification: type Ⅰ to Ⅳ), displacement, age, treatment and complication. Twenty-three patients with a mean age of 12.8 years (range, 3-16 years) with femoral neck fractures were identified and 3 cases with cerebral palsy were excluded. There were 13 male patients and 10 female patients. Nineteen cases underwent operation, includ-ing closed reduction for 15 cases, and open reduction for other 4 cases. Four cases were treated conservation. The mean follow-up was 4 years (range, 1.1-11 years). We studied timing of surgery, type of fixation, and quality of reduction with respect to the primary outcome measure-radiographic evidence of union and avascu-lar necrosis. The BMI and BMD data of latest 3 patients were obtained due to specially trivial injury mecha-nism. Results Eighteen of 19 operated cases have satisfied healing of fracture in good to excellent posi-tions. One patient had Haidukewych classification of fair reduction with delayed union and required hip screw revision and bone grafting. One had coxa varus, one had coxa valgus. Four patients were treated more than 24 hours after injury, including the patient who had delayed union. The mean time to fixation for the remaining patients was 11.2 hours after injury. The BMI and BMD data of 3 patients were abnormal when compared with children of the same age group. Conclusion The study shows that closed or open reduction, decompression and cannulated screw stable internal fixation for femoral neck fractures in children should be a standard treatment which leads to satisfactory results without occurrence of avascular necrosis. Key words: Child; Femoral neck fractures; Femur head necrosis

Multi-slice spiral CT 3-dimensional reconstruction technique to treat multi-segmental degenerative spinal stenosis with traumatic instability of lower cervical spine

To study the feasibility of multi-slice spiral computed tomography (MSCT) 3-dimensional reconstruction technique in assisting cervical pedicle screw fixation (PSF) and double-door laminoplasty to treat multi-segmental degenerative spinal stenosis with traumatic instability (MDSTI) of lower cervical spine. From September 2006 to August 2007, PSF combined with double-door laminoplasty was performed in 9 patients with MDSTI of lower cervical spine. MSCT 3-dimensional reconstruction techniques, including volume rendering (VR) and multi-planar reconstruction (MPR), were used to assist preoperative diagnosis and measurement to guide the procedure. MPR was performed after operation. In coronal view, the degree of screw perforation was measured precisely and the different positions of pedicle screws were divided into three grades according to Richter's method. In axial view, the canal sagittal diameter and transverse area of every laminoplasty level were measured. Nine patients with MDSTI of lower cervical spine underwent PSF (total 44 screws). According to the classification of Richter, 72.7% (32/44) was in Grade 1 and 27.3% (12/44) was in Grade 2. No screw perforation occurred in Grade 3 and no screw revision was done for misplacement. No iatrogenic damage was observed. Double-door laminoplasty was performed in total 42 volumes. The postoperative sagittal diameter and transverse area of cervical spinal canal were significantly increased (P<0.05). The confidence intervals of mean increased ratio were 23.43%-40.65% in sagittal diameter and 23.18%-42.07% in transverse area. Six months after laminoplasty, based on MSCT axial view, complete union between "open door" and allograft bone was obtained in 76.19% of volumes (32/42), and allograft bone was absorbed partly in 23.81% (10/42). A solid union in bilateral gutters was achieved in all cases. They were followed up from 6 months to 1 year (mean 7.8 months). Postoperative neural function recovery in two cases improved 2 ASIA grade, 5 cases improved 1 grade and 2 cases remained the same as preoperative grade. No cases had lower ASIA grade. Assisted with MSCT 3-dimensional reconstruction technique, PSF combined with double-door laminoplasty can be performed more safely and effectively to treat patients with MDSTI of lower cervical spine.