Tag: screw misplacement

Posted on

Freehand screw insertion technique without image guidance for the cortical bone trajectory screw in posterior lumbar interbody fusion

J Neurosurg Spine 36:1–7, 2022

Cortical bone trajectory (CBT) screw insertion using a freehand technique is considered less feasible than guided techniques, due to the lack of readily identifiable visual landmarks. However, in posterior lumbar interbody fusion (PLIF), after resection of the posterior anatomy, the pedicles themselves, into which implantation is performed, are palpable from the spinal canal and neural foramen. With the help of pedicle wall probing, the authors have placed CBT screws using a freehand technique without image guidance in PLIF. This technique has advantages of no radiation exposure and no requirement for expensive devices, but the disadvantage of reduced accuracy in screw placement. To address the problem of symptomatic breaches with this freehand technique, variables related to unacceptable screw positioning and need for revisions were investigated.

METHODS From 2014 to 2020, 182 of 426 patients with single-level PLIF were enrolled according to the combined criteria of L4–5 level, excluding cases of revision and isthmic spondylolisthesis; using screws 5.5 mm in diameter; and operated by right-handed surgeons. We studied the number of misplaced screws found and replaced during initial sur- geries. Using multiplanar reconstruction CT postoperatively, 692 screw positions on images were classified using previ- ously reported grading criteria. Details of pedicle breaches requiring revisions were studied. We conducted a statistical analysis of the relationship between unacceptable (perforations > 2 mm) misplacements and four variables: level, lateral- ity, spinal deformity, and experiences of surgeons.

RESULTS Three screws in L4 and another in L5 were revised during initial surgeries. The total rate of unacceptable screws on CT examinations was 3.3%. Three screws in L4 and another in L5 breached inferomedial pedicle walls in grade 3 and required revisions. The revision rate was 2.2%. The percentage of unacceptable screws was 5.2% in L4 and 1.7% in L5 (p < 0.05), whereas other variables showed no significant differences.

CONCLUSIONS A freehand technique can be feasible for CBT screw insertion in PLIF, balancing the risks of 3.3% unacceptable misplacements and 2.2% revisions with the benefits of no radiation exposure and no need for expensive devices. Pedicle palpation in L4 is the key to safety, even though it requires deeper and more difficult probing. In the initial surgeries and revisions, 75% of revised screws were observed in L4, and unacceptable screw positions were more likely to be found in L4 than in L5.

Posted on

Management of C1–2 traumatic fractures using an intraoperative 3D imaging–based navigation system

Management of C1–2 traumatic fractures using an intraoperative 3D imaging–based navigation system

J Neurosurg Spine 22:128–133, 2015

Fractures of C-1 and C-2 are complex and surgical management may be difficult and challenging due to the anatomical relationship between the vertebrae and neurovascular structures. The aim of this study was to evaluate the role, reliability, and accuracy of cervical fixation using the O-arm intraoperative 3D image–based navigation system.

Methods The authors evaluated patients who underwent a navigation system–based surgery for stabilization of a fracture of C-1 and/or C-2 from August 2011 to August 2013. All of the fixation screws were intraoperatively checked and their position was graded.

Results The patient population comprised 17 patients whose median age was 47.6 years. The surgical procedures were as follows: anterior dens screw fixation in 2 cases, transarticular fixation of C-1 and C-2 in 1 case, fixation using the Harms technique in 12 cases, and occipitocervical fixation in 2 cases. A total of 67 screws were placed. The control intraoperative CT scan revealed 62 screws (92.6%) correctly placed, 4 (5.9%) with a minor cortical violation (< 2 mm), and only 1 screw (1.5%) that was judged to be incorrectly placed and that was immediately corrected. No vascular injury of the vertebral artery was observed either during exposition or during screw placement. No implant failure was observed.

Conclusions The use of a navigation system based on an intraoperative CT allows a real-time visualization of the vertebrae, reducing the risks of screw misplacement and consequent complications.

Posted on

Accuracy of pedicle screw placement in the lumbosacral spine using conventional technique: CT postoperative assessment in 102 consecutive patients

Journal of Neurosurgery: Spine. March 2010.DOI: 10.3171/2009.9.SPINE09261

The goal of this study was to determine the incidence of screw misplacement and complications in a group of 102 patients who underwent transpedicle screw fixation in the lumbosacral spine with conventional open technique and intraoperative fluoroscopy. The results are compared with published data.

Methods: Cases involving 102 consecutive patients (424 inserted screws) were reviewed. Surgery was performed in all cases by the same surgeon’s team, using the same implant, and all results were assessed by means of a specific CT protocol. The screw position was assessed by the authors and an independent observer. Screw position was classified as correct when the screw was completely surrounded by the pedicle cortex, as “cortical encroachment” (questionable violation) if the pedicle cortex could not be visualized, and as “frank penetration” when the screw was outside the pedicular boundaries. Frank penetration was further subdivided as minor (when the edge of the screw thread was up to 2.0 mm outside the pedicle cortex), moderate (2.1–4 mm), and severe (> 4 mm). The incidence of intra- and postoperative complications not related to screw position as well as hardware failures were also registered, with a minimum follow-up duration of 8 months.

Results: The rate of frank pedicle screw misplacement was 5%. The rate of minimal or questionable pedicle wall violation was 2.8%. Among the frank misplacements, 6 were classified as minor, 12 as moderate, and 3 as severe penetration. Two patients (2%) had radicular pain and neurological deficits (inferomedial and inferolateral minor misplacement at L-4 and L-5, respectively), and 5 patients (4.9%) complained only of radicular pain. At the follow-up examination all patients had completely recovered their neurological function and radicular pain was resolved in all cases. The complications not related to screw malposition were 2 pedicle fractures (2% of patients), 1 nerve root injury (1%), and 1 dural laceration (1%). Five patients (4.8%) had postoperative anemia and required transfusions. Superficial or deep wound infection was noted in 3 patients (2.9%). Late hardware failure occurred in 2 patients (2%). One patient developed adjacent segmental instability and required additional surgery to extend the fusion.

Conclusions: Our rates of screw misplacement and complications compare favorably with the lowest rates of the series in which conventional technique was used and are close to the rates reported for image-guided methods. The risk of malpositioning may be reduced with careful preoperative surgical planning, accurate knowledge of the spinal anatomy, surgical experience, and correct indication for conventional surgery. The conventional technique still remains a practical, safe, and effective surgical method for lumbosacral fixation.

Proudly powered by WordPress