Title Risk factors of recurrent lumbar disk herniation : A single center study

Background. The recurrence of lumbar disc herniation (LDH) is a major problem in the treatment of LDH. The purpose of this study was to investigate the risk factors for recurrent LDH. Methods. Between April, 2005 and March, 2008, 298 patients with LDH, who underwent surgical treatment, were enrolled in this study. The patients were divided into a non-recurrent group (N group) and a recurrent group (R group). We compared their clinical parameters including age, gender, body-mass index (BMI), smoking, alcohol, sports activity, occupational lifting, and occupational driving. The relationships between the variables and recurrent LDH were evaluated by univariate analysis and multiple logistic regression analysis. Results. The N group had 266 patients (89.3%) and the R group had 32 patients (10.7%). Univariate analysis showed that current smoking (P < 0.001) and occupational lifting (P = 0.02) significantly correlated with recurrent LDH. Multivariate analysis showed that current smoking significantly related with recurrent LDH (OR=3.47, 95% CI: 1.55-7.80, P=0.003). Conclusions. Our study suggests that smoking cessation and restraining from lifting may significantly decrease the incidence of recurrent LDH. INTRODUCTION Lumbar disc herniation (LDH) is one of the most frequent diseases of the lumbar diseases. Treatments of LDH are comprised of conservative and surgical treatments. In our institute, we choose surgical treatment in cases that show no response to conservative treatment for three months, and in patients who suffer from motor palsy, sensory palsy, or bowel bladder disturbance. A large proportion of patients with LDH obtain satisfactory results, but there remain some cases with unsatisfactory results. The overall rate of unsatisfactory results following discectomy is between 5% and 20%. The causes of failure of discectomy are surgery performed at the wrong segment, insufficient removal of herniated and degenerative changed disc tissue, unrecognized second disc herniation, trauma of a nerve root, unrecognized displaced sequestration, insufficient decompression of spinal stenosis, tumors, spondylolisthesis, extravertebral nerve compression, and polyneuropathia. Recurrent LDH has been reported in 5–15% of patients after disc excision. Therefore, the recurrence of LDH is a major problem in the surgical treatment of LDH. It is important to analyze the risk factors of recurrent LDH in order to prevent recurrence. In this study, we investigated the frequency of recurrent LDH and analyzed the risk factors for recurrent LDH by comparing clinical parameters including age, gender, BMI, smoking, alcohol, sports activity, occupational lifting, and occupational driving. MATERIALS AND METHODS Patients A total of 298 patients, who underwent microdiscectomy for LDH from April, 2005 to March, 2008 in Saiseikai Kanazawa Hospital, were included in this study. The levels of disc herniation were L1–L2 in 2 cases (0.7%), L2–L3 in 10 cases (3.4%), L3–L4 in 38 cases (12.8%), L4–L5 in 145 cases (48.7%), and L5–S1 in 103 cases (34.6%). All of the patients were diagnosed radiologically by magnetic resonance imaging (MRI). All the patients or relatives gave informed consent to participate in this study. The patients were divided into a recurrent group (R group) and a non-recurrent group (N group), and their clinical parameters were compared including age, sex, body-mass index (BMI), smoking, alcohol, sports activity, occupational lifting, occupational driving, and the type of herniation. Recurrent LDH was defined as a disc herniation at the same level, regardless of ipsilateral or contralateral herniation, in a patient who experienced a pain-free interval of at least 6 months after prior surgery. All patients with recurrent LDH underwent repeat surgery and the herniated discs were detected at the same level as the primary discectomy. Operative technique Surgery was performed by two surgeons using microdiscectomy techniques. The lamina was partially resected and partial discectomy was done after retracting the nerve root medially. We made a small square window through the annulus, each side measuring about 3 mm, and removed the herniated disc and about 1/3 of the disc material. We left the annular window open without any covering after surgery. The type of herniation was classified as protrusion, subligamentous extrusion, transligamentous extrusion, and sequestration after review of the surgical records. Physical findings Each subject’s height and weight were recorded and body mass index (BMI) was calculated. The cutoff point between low and high values was set at 25 kg/m according to the criteria of the Japan Society for the Study of Obesity. Questionnaire A questionnaire of physical and lifestyle factors was given to all patients to complete at the time of admission. The following questions concerning current smoking habits, current drinking habits, occupational lifting, occupational driving, and sports history were used for the analysis: Do you smoke cigarettes? Do you drink alcoholic beverages? Have you ever engaged in an occupation that involved lifting weight? Have you worked as an occupational driver? Have you ever participated in a