Posterior Atlantoaxial Screw Placement in a Portuguese Population: A Morphometric Analysis Based on Computed Tomography Scan Measurements

Martins, Rita Santos; Pereira, Catarina Silva; Lemos, Carolina; Rodrigues-Pinto, Ricardo

doi:10.1055/s-0042-1744502

Acessibilidade / Reportar erro

Brasil

Revista Brasileira de Ortopedia

Español English

Brasil

Español English

sumário « anterior atual seguinte »

Sumário

Original Article • Rev. bras. ortop. 58 (1) • Jan-Feb 2023 • https://doi.org/10.1055/s-0042-1744502 copy

Posterior Atlantoaxial Screw Placement in a Portuguese Population: A Morphometric Analysis Based on Computed Tomography Scan Measurements

Authorship SCIMAGO INSTITUTIONS RANKINGS

Abstract

Objective

The present study aims to evaluate the screw length and trajectory angles for posterior atlantoaxial fixation in a Portuguese population, through the study of cervical computed tomography (CT) scans.

Methods

Cervical CT scans of 50 adults were measured according to predefined screw trajectories of C1-C2 transarticular (C1C2TA), C1 lateral mass (C1LM), C2 pedicle (C2P), C2 pars and C2 laminar (C2L) screws. For each of these trajectories, screw length and angles were measured and compared between males and females.

Results

For the C1C2TA screw trajectory, the mean length, medial, and cranial angles were 34.12 ± 3.19 mm, 6.24° ± 3.06, and 59.25° ± 5.68, respectively, and for the C1LM screw trajectory, they were 27.12 ± 2.15 mm, 15.82° ± 5.07, and 13.53° ± 4.80, respectively. The mean length, medial, and cranial angles for the C2P screw trajectory were 23.44 ± 2.49 mm, 27.40° ± 4.88, and 30.41° ± 7.27, respectively; and for the C2 pars screw trajectory, they were 16.84 ± 2.08 mm, 20.09° ± 6.83, and 47.53° ± 6,97. The mean length, lateral, and cranial angles for the C2L screw trajectory were 29.10 ± 2.48 mm, 49.80° ± 4.71, and 21.56° ± 7.76, respectively. There were no gender differences except for the lengths of the C1C2TA (p= 0,020) and C2L (p= 0,001) screws, which were greater in males than in females.

Conclusion

The present study provides anatomical references for the posterior atlantoaxial fixation in a Portuguese population. These detailed data are essential to aid spine surgeons to achieve safe and effective screw placement.

Keywords
atlantoaxial joint; bone screws; cervical vertebrae; joint instability; surgical fixation devices

		Age
Gender	n	Mean	SD
Male	26	40.08	15.81
Female	24	45.38	14.45
Total	50	42.62	15.25

Screw trajectory		Interobserver reliability
C1C2TA	Length	0.441
	Medial angle	0.598
	Cranial angle	0.674
C1LM	Length	0.214
	Medial angle	0.691
	Cranial angle	0.427
C2P	Length	0.709
	Medial angle	0.828
	Cranial angle	0.747
C2 pars	Length	0.573
	Medial angle	0.795
	Cranial angle	0.784
C2L	Length	0.593
	Lateral angle	0.605
	Cranial angle	0.651

		n	Minimum	Maximum	Mean	SD
C1C2TA	Length	50	28.00	40.00	34.12	3.19
	Medial angle	50	2.00	13.00	6.24	3.06
	Cranial angle	50	45.00	70.00	59.25	5.68
C1LM	Length	50	23.00	33.00	27.12	2.15
	Medial angle	50	4.00	28.00	15.82	5.07
	Cranial angle	50	6.00	25.00	13.53	4.80
C2P	Length	50	19.00	28.00	23.44	2.49
	Medial angle	50	18.00	38.00	27.40	4.88
	Cranial angle	50	18.00	43.00	30.41	7.27
C2 pars	Length	50	14.00	24.00	16.84	2.08
	Medial angle	50	9.00	33.00	20.09	6.83
	Cranial angle	50	31.00	60.00	47.53	6.97
C2L	Length	50	24.00	33.00	29.10	2.48
	Lateral angle	50	36.00	59.00	49.80	4.71
	Cranial angle	50	3.50	34.50	21.56	7.76

Screw trajectory		Gender	n	Mean	SD	SED	p-value
C1C2TA	Length	Male	26	35.15	2.66	0.52	0.020
	Length	Female	24	33.00	3.39	0.69	0.020
	Medial angle	Male	26	5.71	2.78	0.55	0.207
	Medial angle	Female	24	6.81	3.30	0.67	0.207
	Cranial angle	Male	26	58.79	5.21	1.02	0.555
	Cranial angle	Female	24	59.75	6.23	1.27	0.555
C1LM	Length	Male	26	27.69	2.09	0.41	0.050
	Length	Female	24	26.50	2.09	0.43	0.050
	Medial angle	Male	26	16.46	5.26	1.03	0.357
	Medial angle	Female	24	15.13	4.86	0.99	0.357
	Cranial angle	Male	26	13.12	4.78	0.94	0.531
	Cranial angle	Female	24	13.98	4.90	1.00	0.531
C2P	Length	Male	26	23.58	2.58	0.51	0.690
	Length	Female	24	23.29	2.44	0.49	0.690
	Medial angle	Male	26	27.00	4.18	0.82	0.551
	Medial angle	Female	24	27.83	5.59	1.14	0.551
	Cranial angle	Male	26	28.60	7.00	1.37	0.066
	Cranial angle	Female	24	32.38	7.18	1.47	0.066
C2 pars	Length	Male	26	17.29	2.27	0.45	0.131
	Length	Female	24	16.38	1.77	0.36	0.131
	Medial angle	Male	26	18.83	6.42	1.26	0.176
	Medial angle	Female	24	21.46	7.12	1.45	0.176
	Cranial angle	Male	26	46.10	6.90	1.35	0.131
	Cranial angle	Female	24	49.08	6.85	1.40	0.131
C2L	Length	Male	26	30.15	2.29	0.45	0.001
	Length	Female	24	27.96	2.18	0.44	0.001
	Lateral angle	Male	26	48.96	4.58	0.90	0.193
	Lateral angle	Female	24	50.71	4.77	0.97	0.193
	Cranial angle	Male	26	20.92	8.11	1.59	0.551
	Cranial angle	Female	24	22.25	7.47	1.52	0.551

					International literature
Trajectory	Present study				Nogueira-Barbosa et al.¹⁴14 Nogueira-Barbosa MH, Defino HL. Multiplanar reconstructions of helical computed tomography in planning of atlanto-axial transarticular fixation. Eur Spine J 2005;14(05):493-500	Young Hu et al.²¹21 Hu Y, Dong WX, Spiker WR, et al. An anatomic study to determine the optimal entry point, medial angles, and effective length for safe fixation using posterior C1 lateral mass screws. Spine (Phila Pa 1976) 2015;40(04):E191-E198	Simsek et al.¹⁸18 Simsek S, Yigitkanli K, Seçkin H, et al. Ideal screw entry point and projection angles for posterior lateral mass fixation of the atlas: an anatomical study. Eur Spine J 2009;18(09):1321-1325	Rocha et al.²⁰20 Rocha R, Safavi-Abbasi S, Reis C, et al. Working area, safety zones, and angles of approach for posterior C-1 lateral mass screw placement: a quantitative anatomical and morphometric evaluation. J Neurosurg Spine 2007;6(03):247-254	Chin et al.²⁷27 Chin KR, Mills MV, Seale J, Cumming V. Ideal starting point and trajectory for C2 pedicle screw placement: a 3D computed tomography analysis using perioperative measurements. Spine J 2014;14(04):615-618	Kiran et al.²⁴24 Sai Kiran NA, Sivaraju L, Vidyasagar K, et al. Safety and Accuracy of Anatomic and Lateral Fluoroscopic-Guided Placement of C2 Pars/ Pedicle Screws and C1 Lateral Mass Screws, and Freehand Placement of C2 Laminar Screws. World Neurosurg 2018;118: e304-e315	Dean et al.²⁸28 Dean CL, Lee MJ, Robbin M, Cassinelli EH. Correlation between computed tomography measurements and direct anatomic measurements of the axis for consideration of C2 laminar screw placement. Spine J 2009;9(03):258-262
	Gender	n	Mean	Total
C1C2TA length	Male	26	35.15	34.12	38.86
C1C2TA length	Female	24	33.00	34.12	36.99
C1C2TA medial angle	Male	26	5.71	6.24	7.57
C1C2TA medial angle	Female	24	6.81	6.24	7.48
C1C2TA cranial angle	Male	26	58.79	59.25	58.64
C1C2TA cranial angle	Female	24	59.75	59.25	57.30
C1LM length	Male	26	27.69	27.12		21.86	19.59	30.40
C1LM length	Female	24	26.50	27.12		21.86	19.59	30.40
C1LM medial angle	Male	26	16.46	15.82		20.86	13.50	16.70
C1LM medial angle	Female	24	15.13	15.82		20.86	13.50	16.70
C1LM cranial angle	Male	26	13.12	13.53		15.00	15.20	21.70
C1LM cranial angle	Female	24	13.98	13.53		15.00	15.20	21.70
C2P length	Male	26	23.58	23.44					22.10
C2P length	Female	24	23.29	23.44					22.10
C2P medial angle	Male	26	27.00	27.40					27.90
C2P medial angle	Female	24	27.83	27.40					27.90
C2P cranial angle	Male	26	28.60	30.41					23.00
C2P cranial angle	Female	24	32.38	30.41					23.00
C2 pars length	Male	26	17.19	16.8						16.40
C2 pars length	Female	24	16.38	16.8						16.40
C2 pars medial angle	Male	26	18.83	20.09						22.70
C2 pars medial angle	Female	24	21.46	20.09						22.70
C2 pars cranial angle	Male	26	46.10	47.53						30.00
C2 pars cranial angle	Female	24	49.08	47.53						30.00
C2L length	Male	26	30.15	29.10							28.80
C2L length	Female	24	27.96	29.10							28.80
C2L lateral angle	Male	26	48.96	49.80							42.45
C2L lateral angle	Female	24	50.71	49.80							42.45
C2L cranial angle	Male	26	20.92	21.56
C2L cranial angle	Female	24	22.25	21.56

Sociedade Brasileira de Ortopedia e Traumatologia Al. Lorena, 427 14º andar, 01424-000 São Paulo - SP - Brasil, Tel.: 55 11 2137-5400 - São Paulo - SP - Brazil
E-mail: rbo@sbot.org.br

Acompanhe os números deste periódico no seu leitor de RSS

[1] Address for correspondence Ricardo Rodrigues-Pinto, PhD, Spinal Unit (UVM), Department of Orthopaedics, Centro Hospitalar Universitário do Porto, Largo do Prof. Abel Salazar, Porto, 4099-001, Portugal (e-mail: ric_pinto@hotmail.com).