The effect of age on result of straight leg raising test in patients suffering lumbar disc herniation

Ninety percent of all people sometimes during their lives experience low back pain, and 30-40% develops radicular leg pain with the sciatica characteristics. Although for clinical diagnosis of lumbar disc herniation (LDH) straight leg raising (SLR) test in 85-90% of cases indicates LDH, but in our practice with LDH patients this test is frequently negative despite radicular leg pain due to LDH. Hence, we decided to evaluate this test in LDH in different age groups. All patients with leg pain referring to neurosurgery clinic were enrolled. Those with a history of pain other than sciatica excluded and SLR test and magnetic resonance imaging (MRI) of the lumbosacral spine performed. The patients with negative MRI findings excluded and finally 269 patients with true sciatica and positive MRI were included. SLR tests were performed for different age groups. Of 269 patients, 167 were male. The age range was 16-80 years. The most involved levels were L5-S1 47%) and L4-L5 (42%), respectively. The rate of positive SLR result, which was 100%, 87% and 82% for 10-19, 20-29 and 30-39 years age group respectively. With an increment of age, the rate of positive test regularly declined. The chance of positive SLR in men is 1.3 times the women (odds ratio [OR] 2.4; 95% confidence interval [CI] = 1.265-4.557; P = 0.007). Increasing the age has suppression effect in positivity of SLR so that for each 1-year the chance of SLR become 0.27 times less to become positive and this is also statically meaningful (OR = 0.271;95% CI = 0.188-0.391; P,0.001). The chance of positive SLR for patients under 60 is 5.4 folds more than patients above 60 years old (OR = 5.4; 95% CI = 4-8.3; P, 0.001). Age, sex (male), and disk level had statistically the effect on SLR positive test.