婦女產後背痛之危險因子

Abstract

背景：婦女懷孕時發生背痛(pregnancy-related back pain)的機率大約為65%~70%。根據過去文獻，造成懷孕時背痛產生的主要原因 (etiology)有三點：一、生物力學/骨骼肌肉 (Biomechanical/ musculoskeletal) 因素：包括體重增加、身形變化、姿勢重心位置改變、肌肉能力、身體活動(physical activity)等；二、賀爾蒙 (hormonal) 因素：鬆弛素(relaxin)的作用；三、血管性 (vascular) 因素：水分滯留。在產後，上述原因的影響雖部分消失，但根據脊柱穩定系統理論，因其所致而留存的肌肉骨骼問題仍有可能影響產後背痛(postpartum back pain)的發生。然而目前僅有少數研究探討產後仍存的背痛問題。 研究目的：了解(1)產後背痛的盛行率；(2)探討懷孕時發生背痛、且產後仍有背痛的婦女與產後無背痛者，其生物力學/骨骼肌肉因子的差異；(3)生物力學/骨骼肌肉因子與產後持續背痛的相關性。 研究方法：以橫斷性(cross-sectional)設計了解產後背痛的盛行率以及產後疼痛組與無痛組在產後第四至六週其生物力學/骨骼肌肉因子的差異；並以縱貫性(longitudinal)研究探討婦女產後第四至六週之生物力學/骨骼肌肉因子對產後第三個月持續背痛的影響。合乎收案條件的受試者在產後第一次回診(產後四至六週)時即接受評估，除了記錄基本資料之外，還包括:背痛分數、站立脊椎角度、背部和腹部肌力與肌耐力、關節鬆弛度、歐氏失能指數、身體活動、心理問卷等產後背痛相關因子之量測，於產後第三個月時追蹤背痛持續情形。使用SPSS 17.0作為統計分析工具，以獨立樣本T檢驗(independent T-test)或曼惠特尼檢定(Mann-Whitney U test)分析產後第四至六週其疼痛組與無痛組在生物力學/骨骼肌肉因子之間的差異；以皮爾森相關(Pearson correlation)、斯皮爾曼等級相關(Spearman correlation)及邏輯迴歸(logistic regression)分析產後第三個月仍持續背痛與產後第四至六週其生物力學/肌肉骨骼因子之相關性。 結果：產後四至六週背痛的盛行率為37%，從懷孕時發生背痛到產後第三個月仍持續背痛的盛行率為11% (17/144)。不論在產後四至六週或產後第三個月，背痛分數與歐氏失能指數皆達中度相關(r=0.58，p<0.0005；r=0.53，p=0.004)。產後四至六週，無痛組(58人)與疼痛組(35人)在生物力學/骨骼肌肉因子間無顯著差異；其他因素方面，兩組在身體活動量、懷孕時的工作是否有持續坐或站大於四小時和無痛分娩的比例有顯著差異(p=0.02；p=0.023；p=0.02)。在產後第三個月，無持續疼痛組(11人)與仍持續疼痛組(17人)在產後第四至六週腹肌等級分佈上有顯著差異(p＜0.05；p=0.03)。以邏輯迴歸分析未發現影響產後第三個月仍持續背痛的危險因子。 討論與結論：發生產後背痛的婦女與肌肉骨骼次系統失衡、產後繁瑣家務活動增加有關。建議日後探討產後婦女其生物力學/骨骼肌肉因子與背痛的關係，除增加受試者人數外，另需評估腹部深層肌群肌肉能力，與可能發生的代償現象。

Background: The incidence of pregnancy-related back pain in pregnant women is about 65%~70%. According to previous studies, the etiologies of pregnancy-related back pain during pregnancy are: (1) Biomechanical/ musculoskeletal effect: weight gain, body shape change, alteration of the center of gravity, muscle strength and endurance, change of physical activity level; (2) Hormonal effect:the relaxin; (3) Vascular effect: water retention. However, the influenus of those effects to postpartum back pain are still unclear. Furthermore, according to spine stability system, changes of passive and active subsystems from pregnancy maybe unprevented after delivery, the postpartum back pain is likely to persist. At present, only few studies focus on the postpartum back pain. Purposes: The study will investigate: (1) the prevelance of the postpartum low back pain; (2) the differences of the biomechanical/ musculoskeletal factors between women with postpartum back pain and those without postpartum back pain; (3) the correlation between the biomechanical/ musculoskeletal factors and back pain at postpartum fourth-sixth weeks and the third month. Methods: This study is a cross-sectional design to investigate the differences between women with postpartum back pain and without back pain, and also to determine the biomechanical/ musculoskeletal effects on the persisted postpartum back pain by longitudinal design. Women with pregnancy-related back pain will be recruited from Taiwan Adventist Hospital at postpartum fourth-sixth weeks. These subjects will receive physical examinations by a physical therapist. It will include the back pain scale (VAS), spinal angle on quite standing, the muscle performance of back and abdomen muscle groups, joint laxity, the Oswestry Disability Index (ODI), International Physical Activity Questionnaire-Short Form (IPAQ) and Center of Epidemiological Study Depression (CES-D), and those were partial in fourth-sixth weeks were followed until postpartum 3rd month. All analyses will be performed with SPSS 17.0. Independent T-test or Mann-Whitney U test will be used to compare the differences of biomechanical/ musculoskeletal factors between postpartum vii women with back pain and without back pain. Pearson correlation or Spearman correlation and logistic regression will be used to analyze the correlation between persisting back pain of postpartum 3rd month and biomechanical/ musculoskeletal factors at postpartum fourth-sixth weeks. Results: The prevelance of postpartum low back pain at fourth-sixth weeks was 37%, the persisted low back pain from pregnancy to postpartum 3rd month was 11% (17/144). The correlation between VAS and ODI showed moderately correlated whether at postpartum fourth-sixth weeks or postpartum 3rd month. (r=0.58，p<0.0005；r=0.53，p=0.004) For all the biomechanical/ musculoskeletal factors, there was no significant difference between pain-free group (n=58) and painful group (n=35). In the others factors, the physical activity, the work status during pregnancy and the ratio of epidural anesthesia were showed significant difference between pain-free group and painful group (p=0.02; p=0.023; p=0.02).The ratio of abdominal muscles grading at fourth-sixth weeks showed significantly different between pain-free group (n=11) and painful group (n=17) (p＜0.05；p=0.03) at postpartum 3rd month. Throughout the study, there was no finding in the risk factor of persistent postpartum low back pain. Conclusions: The musculoskeletal subsystem imbalance and tedious housework were associated with postpartum low back pain. In the future, we suggest to increase the subject number and to assess the deep muscles for the compensatory phenomenon that may occur between the relationship of women with postpartum back pain and the biomechanical / musculoskeletal factors.