Application of a novel computer-assisted surgery system in percutaneous nephrolithotomy: A controlled study

Table 1 Baseline characteristics of patients and stones in the two groups

Characteristics	CAS group (n = 30)	Control group (n = 30)	P value
Age, yr, mean ± SD	52.30 ± 14.37	49.57 ± 13.58	0.452
Gender, n (%)			0.301
Male	14 (47)	18 (60)
Female	16 (53)	12 (40)
BMI, kg/m2, mean ± SD	25.24 ± 3.58	25.29 ± 5.12	0.968
Dilation of the collecting system1, n (%)			0.635
No or mild	18 (60)	20 (66)
Moderate	8 (27)	5 (17)
Severe	4 (13)	5 (17)
Stone side, n (%)			0.426
Left	17 (57)	20 (67)
Right	13 (43)	10 (33)
Stone type, n (%)			0.434
Partial staghorn stone	4 (13)	8 (27)
Complete staghorn stone	6 (20)	5 (17)
Multiple stone	20 (67)	17 (56)
Stone density, Hounsfield units, mean ± SD	915.15 ± 334.85	824.69 ± 245.73	0.238
Stone sectional area, mm2, mean ± SD	562.95 ± 405.58	497.59 ± 566.88	0.174

¹It was mild when the dilation distance of the collecting system was less than 2 cm. It was moderate when the dilation distance was between 2 cm and 4 cm. It was severe when the dilation distance was more than 4 cm. The dilation distance of the collecting system was measured when it was longest.

CAS: Computer-assisted surgery; SD: Standard deviation.

Table 2 Planning characteristics of tracts in two groups

Characteristics	CAS group (n = 30)	Control group (n = 30)	P value
Entry calyx1, n (%)			0.413
Upper calyx	6 (20)	3 (10)
Middle calyx	17 (57)	22 (73)
Lower calyx	7 (23)	5 (17)
Tract length1, mm, mean ± SD	76.03 ± 13.26	82.53 ± 17.58	0.111
Tract number, n (%)			1.000
1	26 (87)	27 (90)
2	4 (13)	3 (10)

¹Entry calyx and tract length were collected from the first tract if there were two tracts.

CAS: Computer-assisted surgery; SD: Standard deviation.

Table 3 Perioperative characteristics of percutaneous nephrolithotomy in two groups

Characteristics	CAS group (n = 30)	Control group(n = 30)	P value
Success rate of one puncturing attempt, n (%)	27 (90)	20 (67)	0.028
Operation time, min, mean ± SD	89.20 ± 29.60	92.33 ± 33.08	0.859
Decrease in hemoglobin, g/L, mean ± SD	11.07 ± 8.32	9.03 ± 11.72	0.300
Bleeding1, n (%)	1 (3)	1 (3)	1.000
Urinary tract infection1, n (%)	2 (7)	2 (7)	1.000
Injury1, n (%)	0 (0)	0 (0)	-
Initial stone-free rate, n (%)	26 (87)	19 (63)	0.037

¹Complications were counted and analyzed when Clavien–Dindo grade ≥ 2.

CAS: Computer-assisted surgery; SD: Standard deviation.