Novel free-hand T1 pedicle screw method: Review of 44 consecutive cases

Abstract

Summary of Background Data:Multilevel posterior cervical instrumented fusions are becoming more prevalent in current practice. Biomechanical characteristics of the cervicothoracic junction may necessitate extending the construct to upper thoracic segments. However, fixation in upper thoracic spine can be technically demanding owing to transitional anatomy while suboptimal placement facilitates vascular and neurologic complications. Thoracic instrumentation methods include free-hand, fluoroscopic guidance, and CT-based image guidance. However, fluoroscopy of upper thoracic spine is challenging secondary to vertebral geometry and patient positioning, while image-guided systems present substantial financial commitment and are not readily available at most centers. Additionally, imaging modalities increase radiation exposure to the patient and surgeon while potentially lengthening surgical time.Materials and Methods:Retrospective review of 44 consecutive patients undergoing a cervicothoracic fusion by a single surgeon using the novel free-hand T1 pedicle screw technique between June 2009 and November 2012. A starting point medial and cephalad to classic entry as well as new trajectory were utilized. No imaging modalities were employed during screw insertion. Postoperative CT scans were obtained on day 1. Screw accuracy was independently evaluated according to the Heary classification.Results:In total, 87 pedicle screws placed were at T1. Grade 1 placement occurred in 72 (82.8%) screws, Grade 2 in 4 (4.6%) screws and Grade 3 in 9 (10.3%) screws. All Grade 2 and 3 breaches were <2 mm except one Grade 3 screw breaching 2-4 mm laterally. Only two screws (2.3%) were noted to be Grade 4, both breaching medially by less than 2 mm. No new neurological deficits or returns to operating room took place postoperatively.Conclusions:This modification of the traditional starting point and trajectory at T1 is safe and effective. It attenuates additional bone removal or imaging modalities while maintaining a high rate of successful screw placement compared to historical controls.

Freehand Thoracic Pedicle Screw Placement: Review of Existing Strategies and a Step-by-Step Guide Using Uniform Landmarks for All Levels

“…The search yielded a total of 40 published articles. Following the first selection by title and abstract, we identified seven [ 1 - 4 , 23 , 26 - 27 ] eligible studies that precisely detailed the technique of freehand thoracic pedicle screws placement. Overall, the seven studies represent a total of 1,602 patients with diverse pathologies and 8,586 screws in the thoracic spine.…”

“…There were several pathologies involved in the placement of freehand thoracic screws: from moderate scoliosis (idiopathic and neuromuscular scoliosis) to severe scoliosis (Cobb angle > 90), to infection, Mal de Pott, trauma, tumors, metastasis, and congenital problems (Table 1 ) [ 1 - 4 , 23 , 26 - 27 ].…”

“…Six of the seven studies focused on several thoracic levels. Only one study [ 4 ] focused on just one vertebral level, T1, with a modification of the technique described by Kim, et al [ 2 ]. The details of the different entry points are available in Table 1 .…”

“…Six studies evaluated axial and sagittal trajectories [ 1 - 4 , 23 , 28 ]. Nonetheless, the degree of explanation and details for these trajectories vary greatly.…”

Free-Hand Pedicle Screw Insertion of Thoracic Spine Using Fennell Technique: Initial Results and Review of Literature

“…Various free-hand screw insertion techniques have been described in the literature. [1][2][3][4][5][6] Many of the described trajectories, mention various entry points and medial angulation depending on the level of thoracic spine. Fennell et al 1 described a free-hand pedicle screw insertion technique in the thoracic spine using a uniform entry point and sagittal angulation for all levels in the thoracic spine.…”