Abstract
OBJECTIVE: To validate whether a residual mass demonstrated on early postoperative MR after percutaneous endoscopic lumbar discectomy (PELD) is indeed an intraoperatively retained annulus fibrosus, and explore the correlation between imaging changes in the residual mass and clinical prognosis of patients. METHODS: A prospective study of 118 patients were included. During surgery, a contrast medium, Gadopentetate Dimeglumine, was injected around the ruptured annulus fibrosus. The intensity of the T2 signal, the size of the remaining mass (SR), and the cross-sectional area of the spinal canal (SCSA), VAS, and ODI were assessed at preoperative, 1-h (7-day), 6-month, and 12-month postoperative intervals. Based on VAS at 7 days post-surgery, patients were classified into either a non-remission group (Group A, VAS > 3) or a remission group (Group B, VAS ≤ 3). RESULTS: Six patients who developed recurrent LDH were excluded. A residual mass was detected on MRI 1 h after surgery in 94.6% (106/112). During one year of follow-up, 90.1% (101/112) of the patients displayed fibrous annulus remodeling, although 68.7% (77/112) still exhibited herniation. Significant differences were found in the ODI between Groups A and B one week after surgery (p < 0.001). However, no significant differences were observed in T2 signal intensity, SR, and SCSA at 1-h, 6-month and 12-month post-surgery (p > 0.05) between the two groups. In a multiple linear regression analysis, early postoperative ODI changes were associated with T2 signal (B = -10.22, sig < 0.05), long-term changes were associated with alterations in SR (B = 5.63, sig < 0.05) and SCSA (B = -0.13, sig < 0.05). CONCLUSION: The residual mass observed in early postoperative MR images after PELD was the retained annulus fibrosus intraoperatively. Short-term changes in clinical symptoms after PELD were linked to T2 signal intensity, while long-term changes were associated with changes in SR and SCSA.