Pedicular and Extrapedicular Morphometric Analysis in the Korean Population : Computed Tomographic Assessment Relevance to Pedicle and Extrapedicle Screw Fixation in the Thoracic Spine

Abstract

Objective : To evaluate the anatomical parameters that must be considered when performing thoracic transpedicular or extrapedicular screw fixation. Methods : We selected 958 vertebrae (1,916 pedicles) from 98 patients for analysis. Eight parameters were measured from CT scans : the transverse outer pedicular diameter, transverse inner pedicular diameter, length, angle, chord length of the pedicles and the transverse width, angle, and chord length of the pedicle-rib units. Results : The age of the patients ranged from 21 to 82 years (mean : 48.2 years) and there were 57 men and 41 women. The narrowest transverse outer pedicular diameter was at T5 (4.4 mm). The narrowest pedicle length was at T1 (15.9 mm). For pedicle angle, T1 was 31.6 degrees, which was the most convergent angle, and it showed the tendency of the lower the level, the lesser the convergent angle. The chord length showed a horizontal pattern with similar values at all levels. For the PRU width, T5 showed a similar pattern to the pedicle width at 13.4 mm. For the PRU angle, T1 was the largest angle at 46.2 degrees and the tendency was the lower the level, the narrower the angle. For chord length, T1 was the shortest at 46.9 mm and T8 was the longest at 60.1 mm. Conclusion : When transpedicular screw fixations carried out at the mid-thoracic level, special care must be taken because there is a high chance of danger of medial wall violation. In these circumstances, extrapedicular screw fixation may be considered as an alternative treatment.

Morphometric Measurements of Cadaveric Thoracic Spine in Indian Population and Its Clinical Applications

“…This result again shows that even the smallest available pedicle screw diameter may be too large for mid thoracic segment. Considering the small size of pedicles in thoracic spine, some authors proposed extrapedicular fixation within the pedicle unit to avoid medial wall violation [ 9 , 24 ].…”

Computed tomographic-based morphometric study of thoracic spine and its relevance to anaesthetic and spinal surgical procedures

“…1,[8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] But only few studies, especially in Indian population, have been carried out to quantify thoracic spine morphometric data on CT scanning, the gold-standard for preoperative planning. 1,[24][25][26][27][28][29][30][31][32][33] This study aims at collecting and analyzing the morphometry of thoracic spine in a detailed manner in Indian population and comparing with available literature.…”

Patients with adolescent idiopathic scoliosis of Lenke type-1 curve exhibit specific pedicle width pattern

“…Low-dose spine CT with at least 20-fold reduction of the radiation doses has recently been introduced as a reliable method in the perioperative work-up of scoliosis [12]. Numerous reports on the pedicle morphometry in normal individuals as well as in cadavers and in patients with AIS have been published [13][14][15][16][17][18][19][20]. Many of these studies have pointed out a significant reduction of pedicle width at the concavity of the curve.…”

“…Many of these studies have pointed out a significant reduction of pedicle width at the concavity of the curve. Reports in normal population often include individuals of different age groups that make them unsuitable for comparison with patients with AIS [14,15]. Liljenqvist et al [17,18] were among the first who presented data on pedicle morphometry based on patients data using CT and MRI17, 18, but their assessments were focused only on the morphological changes at the level of scoliotic apex.…”