From: Determining the learning curve for percutaneous endoscopic lumbar interbody fusion for lumbar degenerative diseases
Bridwell grades
Group A, n (%)
Group B, n (%)
Group C, n (%)
p-value
I
12
26 (83.9%)
17
25 (80.6%)
1
27 (87.1%)
0.788
II
14
8
10
III
5
5 (16.1%)
6
6 (19.4%)
4
4 (12.9%)
IV
0