Table 1.

Demographic Data of Patients Who Had Undergone Midline Splitting Laminoplasty (Msl) as a Primary Surgery for Cervical Myelopathy in Miyagi Prefecture between 1988 and 2013.

A. Number and average age of patients
Gender	Number of patients	Average age at surgery (years)
Male	2,868	61 (range: 17-94)
Female	1,340	65 (range: 21-92)
Total	4,208	62 (range: 17-94)
B. Age distribution
Age	Number of patients
≤19	2
20-29	11
30-39	105
40-49	456
50-59	974
60-69	1,390
70-79	1,052
≥80	214
Unknown	4