Long-term outcomes of the repeated lumbar microdiscectomies using polyacrylamide hydrogel: clinico-radiological relevance

Abstract

Background. Epidural fibrosis (EF) is one of the reasons of the failed back surgery syndrome manifesting in back pain and pain in extremities as well as other signs of the compression or irritation of the nerve structures. The numerous approaches to prevent EF have been elaborated. Nowadays, many years of experience in the usage of different barrier materials in microdiscectomy such as polyacrylamide hydrogel (PAH) have been accumulated. Nevertheless, the results of such treatment are rather controversial. The aim of the study was to assess the radiological data on the state of the backbone according to MRI findings and the clinical symptoms of the patients following the surgery as well as to determine the long-term strength of the interaction between the factors under study after the repeated lumbar microdiscectomies performed with intraoperative epidural PAH administration. Materials and methods. The results of the clinical and radiological assessment of 96 patients (mean age 45.7 years; 95 % CI [43.5; 47.9]; 59 males and 37 females) enrolled into the single-center prospective cohort study performed at the State Institution «Romodanov Neurosurgery Institute National Academy of Medical Sciences of Ukraine» have been presented. The patients were divided into two groups. The main group (MG) consisted of 35 (36.5 %) patients with recurrent intervertebtral disc (IVD) herniation to whom PAH was administered epidurally at the final step of the surgery comprising disc removal and decompression of the nervous structures with the aim of preventing cicatrical adhesive EF. In control group (61 patients, 63.5 %), barrier materials were not used. The primary end-points of the study were the long-term outcomes of the repeated lumbar microdiscectomies: EF rate at the postoperative site; the rate of the displacement of spinal root at the postoperative site; the rate of the repeated recurrent IVD herniation and de novo IVD herniation; the rate of the cases with the residual radicular pain localized in the area of the surgical intervention and the extent of the worsening of life quality in the treated patients. The secondary end-points of the study were the following: the analysis of the associations with delineation of the strength of such factorsaffecting the residual radicular pain as EF, the displacement of spinal root at the postoperative site, the repeated recurrent IVD herniation the repeated recurrent IVD herniation and de novo IVD herniation. Results. In 12 months following the surgical treatment, EF frequency was significantly lower in MG as compared with CG where PAH was not used (p = 0.02936). Nevertheless, the difference between groups was not significant when MRI findings of the displacement of spinal root at the postoperative site (р = 0.46759), the frequency of the repeated recurrent IVD herniation (p = 0.90904) and de novo IVD herniation (p = 0.60385) were compared. In study group, there were no association between MRI signs of postoperative EF, the displacement of spinal root or new recurrent IVD herniation on the one hand and the frequency of the radicular pain localized at the area of the surgical intervention on the other hand (p = 0.66482; p = 0.09515; p = 0.22857, respectively). In CG, the significant association between the displacement of spinal root at the postoperative site and the clinical symptoms above was revealed (p = 0.00222) with association coefficient φ = 0.41 indicating the moderate strength of this association. Conclusions. The data obtained generally suggest the reasonability of applying PAH manufactured in Ukraine as a barrier material at least for the treatment of the patients with recurrent IVD herniation representing the challenging category of spinal patients.