Table 5.

Types of complications in 31 (5%) of 633 patients ^a

Complications	All n = 633	I. Respondents n = 491	II. Non-respondents n = 142
Dural tear	9	9
Deep wound infection	5	5
Superficial wound infection	10	9	1
Urinary bladder infection	2	2
Reoperation within the same hospital stay	2	2
Intraoperative nerve root injury	1	1
Postoperative muscle hernia	1		1
Gall bladder infection	1	1
Deep leg vein thrombosis	1	1
Gastric ulcer hemorrhage	1	1
Minor myocardial infarction	1	1
Sum, n (%)	34 (6)	32 (7)	2 (1)

^a 3 of the patients had 2 complications. No complications occurred in consistent non-respondents (group III).