腰椎椎間板ヘルニアに対する内視鏡下椎間板ヘルニア切除術に関する検討―腰痛からみた解析

Microendoscopic Discectomy for Lumbar Disc Herniation. Does the Instability Affect the Low-back Pain?

　腰椎椎間板ヘルニアに対して内視鏡下ヘルニア切除術を施行した42例に対し，術前後の腰痛の程度をvisual analogue scale（以下VAS）を用いて評価した．術前後のVAS値の差を改善値とし，腰痛改善値が20以上の良好群と20未満の不良群に分類した．術前後に腰椎前・後屈X線像を撮影し，手術椎間の前後屈での椎間角と椎間可動域，すべり距離などを計測した．術前と術後の前・後屈時すべり距離は良好群よりも不良群のほうが有意に後方にすべっていた．前・後屈時にみられる腰椎後方すべりは椎間板ヘルニアの腰痛の一因となりうる．

　Microendoscopic discectomy was used to treat lumbar disc herniation in 42 patients, and the intensity of their leg pain, numbness, and low back pain (LBP) measured on a visual analogue scale was recorded before and after surgery. Degree of improvement (DOI) was calculated by the following formula：preoperative score-postoperative score, and the patients were classified into two groups based on the DOI of LBP：a group whose DOI was more than twenty (M group) and a group whose DOI was less than twenty (L group). Lateral radiographs in maximal flexion and extension were obtained before and after microendoscopic discectomy to measure the angle and horizontal displacement (translation) in flexion and extension. There were no statistically significant differences between the two groups in DOI in leg pain or numbness. Preoperative and postoperative translation in flexion and extension in the L group had slipped significantly posteriorly comparison with the M group. These findings suggest that posterior translation in flexion and extension may be a cause of LBP in lumbar disc herniation.