The learning curve and clinical outcome of posterior percutaneous endoscopic cervical discectomy for cervical radiculopathy

English Keywords:Posterior percutaneous endoscopic cervical discectomy  Cervical radiculopathy  Minimally invasive  Learning curve

English Abstract:

  【Abstract】 Objectives: To investigate the learning curve and clinical outcome of posterior percutaneous endoscopic cervical discectomy for cervical radiculopathy. Methods: A retrospective analysis was performed on 54 patients who underwent single-level posterior percutaneous endoscopic cervical discectomy for cervical radiculopathy from May 2015 to May 2016. They were divided chronologically into 2 groups with 27 cases in each group(A and B). The duration of surgery, perioperative complication, hospitalization expense, postoperative hospitalization stay, reoperation rate and clinical outcome were evaluated and compared between the 2 groups. Clinical outcomes were assessed by the visual analogue scale(VAS), neck disability index(NDI) score and modified Macnab criteria in preoperative period as well as 1 month, 6 months and 1 year after surgery. The learning curve was characterized by using two variables regression analysis to establish a cube model(Y=b0+b1X+b2X2+b3X3). Results: The mean duration of follow-up was 15.1±7.8 months, and 42(group A 27 cases, group B 15 cases) patients achieved a minimum follow-up duration of 12 months. The VAS of radicular arm pain and neck pain improved significantly in all the patients at one-year follow-up, so did the NDI. According to Macnab assessment criteria, the surgical outcome was excellent and good in 90.6% patients. The preoperative VAS of neck pain and radicular arm pain of each group was as follows: A, (7.1±0.9)/(7.0±0.8), B, (6.7±0.7)/(7.2±1.0); which at 1 month after surgery was as follows: A, (2.1±1.5)/(1.7±1.6), B, (2.0±0.8)/(1.3±0.5); which at 6 months after surgery was as follows: A, (1.5±1.3)/(1.2±1.2), B, (1.1±1.0)/(0.7±0.7); which at 1 year after surgery was as follows: A, (0.4±0.9)/(0.2±0.6), B, (0.2±0.6)/(0.1±0.3). The preoperative NDI of each group was as follows: A, (55.3±13.7)%, B, (56.9±8.4)%; which at 1 month after surgery was as follows: A, (25.5±14.9)%, B, (17.0±7.1)%; which at 6 months after surgery was as follows: A, (11.3±7.1)%, B, (6.1±3.5)%; which at 1 year after surgery was as follows: A, (4.9±8.0)%, B, (1.8±3.9)%. There was no significantly difference of VAS between group A and group B postoperatively except for one-month after surgery. The improvement of VAS in group A was significantly less than that of group B. No intraoperative complication was observed in two groups. However, postoperative transient radiculitis occurred in 4 patients and was relieved within two weeks, and no significant difference was found between group A(3 cases) and group B(1 case, P=0.610). The duration of surgery of group A was significantly less than that of group B(P=0.001). The learning curve was characterized by using two variables regression analysis to establish a cube model(Y=141.85-5.592X+0.135X2-0.001X3，R2=0.939), which demonstrated that the duration of suegery decreased with the cases accumulation and reached plateau after 22 cases. Conclusions: Posterior percutaneous endoscopic cervical discectomy is a safe and effective option for cervical radiculopathy with its minimally invasive nature. A significant learning curve exists in the surgeon who performs PECD. Proficiency in surgical skill and better in early clinical recovery can be expected after finishing 22 cases, but longer duration of surgery has no impact on the medium-term surgical outcome before that.