The clinical outcome of lateral mass fixation after decompressive laminectomy in cervical spondylotic myelopathy

Peer review under responsibility of Alexandria University Faculty of Medicine.

Available online 11 October 2014

Figures & data

Table 1 Age and gender of the patients.

	Group I (n = 32)		Group II (n = 30)		Test of sig.
	No.	%	No.	%
Sex
Males	22	68.8	18	60.0	p = 0.472
Females	10	31.2	12	40.0
Age (years)
Range	36.0–63.0		40.0–66.0		^ap = 0.123
Mean ± SD	48.0 ± 8.68		51.0 ± 7.73

p: p value for Chi Square test.

a p value for Student t-test.

Table 2 The clinical presentation of the patients.

Clinical data	Group I (n = 32)		Group II (n = 30)		Test of sig.
	No.	%	No.	%
Neck pain	32	100.0	30	100.0	–
Brachialgia	18	56.3	26	86.7	FEp = 0.012^*
Myelopathy	26	81.3	28	93.3
Grade 1	16	61.6	10	35.7	MCp = 0.155
Grade 2	7	26.9	14	50.0
Grade 3	3	11.5	4	14.3
Sphincteric disturbance	11	34.4	10	33.3	p = 0.931

FEp: p value for Fisher Exact test; MCp: p value for Monte Carlo test; p: p value for Chi Square test.

* Statistically significant at p ⩽ 0.05.

Table 3 Operative data of the two groups.

Operative data	Group I (n = 32)	Group II (n = 30)	Test of sig.
Operative time (min)
Range	90.0–140.0	45.0–120.0	<0.001^*
Mean ± SD	110.0 ± 14.16	75.0 ± 24.38
Hospital stay (days)
Range	2.0–7.0	1.0–6.0	0.046^*
Mean ± SD	4.0 ± 1.76	3.0 ± 1.57
Blood loss (ml)
Range	250.0–800.0	100.0–450.0	<0.001^*
Mean ± SD	480.0 ± 193.04	220.0 ± 111.22

^tp: p value for Student t-test.

* Statistically significant at p ⩽ 0.05.

Table 4 Laminectomy levels and fixation in group I.

Levels of laminectomy and fixation	Group I (n = 32)
	No.	%
C3–6	18	56.3
C3–7	8	25.0
C4–7	4	12.5
C4–6	2	6.2

Table 5 Instrument profile.

No. of screws per patient	No. of patients	%
6 screws	2	6.3
8 screws	22	68.7
10 screws	8	25.0
Total no of screws	268	100.0
Thickness of the screws used	No. of screws	%
3.5 mm	252	94.0
4 mm	16	6.0
Average length of screws used	No. of screws	%
12 mm	14	5.2
14 mm	70	26.1
16 mm	160	59.7
18 mm	24	9.0

Table 6 Complications in the 2 groups.

Complications	Group I (n = 32)		Group II (n = 30)		FEp
	No.	%	No.	%
Screw pullout	4	12.5	0	0.0	0.114
Intraoperative spinal cord or nerve root injury	0	0.0	0	0.0	–
Dural tear	2	6.3	1	3.3	1.000
Posterior circulation ischemic manifestation as vertigo	2	6.3	0	0.0	0.492
Postoperative new neurological deficit as myelopathy or radiculopathy	2	6.3	3	10.0	0.667
Vertebral artery injury	0	0.0	0	0.0	–
Superficial wound infection	3	9.4	2	6.7	1.000

FEp: p value for Fisher Exact test.

Figure 1 (A) Preoperative plain X-ray cervical spine lateral view of a male patient 57 years old presented with quadromyelopathy, operated with cervical laminectomy with lateral mass fixation, (B) Preoperative multislice CT cervical spine, (C, D) Sagittal MRI T2 weighted image of the cervical spine of the same patient before surgery, (E, F) fluoroscopic photo of the cervical spine after the insertion of the screws in lateral view of the same patient, (G) operative photo of the same patient after fixation.

Table 7 Outcome as regards the clinical presentation of the patients.

Outcome and Clinical data	Group I (n = 32)		Group II (n = 30)		Test of sig.
	No.	%	No.	%
Neck pain	32	100.0	30	100.0	–
Improved	22	68.8	14	46.7	p = 0.044^*
Stationary	8	25.0	7	23.3
Deteriorated	2	6.2	9	30.0
Brachialgia	18	56.3	26	86.7	FEp = 0.012^*
Improved	15	83.3	16	61.5	MCp = 0.373
Stationary	2	11.1	7	29.9
Deteriorated	1	5.6	3	11.5
Myelopathy	26	81.3	28	93.3
Grade 1	16	61.5	10	35.7	MCp = 0.155
Improved	12	75.0	7	70.0
Stationary	4	25.0	2	20.0	MCp = 0.597
Deteriorated	0	0.0	1	10.0
Grade 2	7	26.9	14	50.0
Improved	4	57.1	8	57.1	MCp = 1.000
Stationary	2	28.6	3	21.4
Deteriorated	1	14.3	3	24.4
Grade 3	3	11.5	4	14.3
Improved	1	33.3	2	50.0	MCp = 1.000
Stationary	2	67.7	1	25.0
Deteriorated	0	0.0	1	25.0
Sphincteric disturbance	11	34.4	10	33.3	p = 0.931
Improved	6	54.5	4	40.0
Stationary	4	36.4	5	50.0	MCp = 0.819
Deteriorated	1	9.1	1	10.0

p, p value for Chi Square test; MCp, p value for Monte Carlo test; FEp, p value for Fisher Exact test.

* Statistically significant difference when p < 0.05.