腿長調整對腿長不等所造成之下背痛及內旋足之效果

Abstract

許多肌肉骨骼症狀與腿長不等存在極高的相關性，這可能是因腿長不等造成承重關節受力不均及肌肉骨骼變形所致。過去文獻發現以增高墊來調整腿長可以有效地減輕因腿長不等而產生的症狀，但卻未曾進行力學分析。因此本研究旨在探討以雷射測距計量測腿長的可能性，並探討以增高墊調整腿長後對於臨床症狀與地面反作用力的變化。其具體目標有四：（一）檢測以雷射測距計測量腿長的信、效度、（二）檢測調整腿長後對於下背疼痛之效果、（三）檢測調整腿長後對於長腳過度內旋之變化、（四）檢測調整腿長後對於地面反作用力之影響。

本研究屬於便利抽樣、前瞻性研究、擬試驗分析、前後測研究的設計，共分為兩部分，第一部分為針對健康人以雷射測距計測量腿長的信、效度研究，第二部分為針對腿長不等者以增高墊介入後之下背痛症狀改變、足型改變、地面反作用力的力學分析等。雷射測距計效度測試方面，使 10 名健康成年之男性接受站立骨盆 X 光照射，並以雷射測距計量測腿長 3 次，以皮爾森相關係數來檢測兩種測 量結果的相關性。在信度測試方面，以同一名測試者在同日進行 15 名健康成年人之雷射測距計量測腿長 2 回，每回 3 次，取平均值分析，使用組內相關係數 ICC(3,3)及測量標準誤，用以計算測試者內信度。在增高墊介入研究部分，徵召結構性腿長不等且以長腳內旋代償並有慢性下背痛之受試者 30 名。每名受試者皆接受下背 疼痛情形、足部形態、站立或行走時地面反作用力的力學分析等量測。下背疼痛的評估採用疼痛量表及修訂過之歐式下背痛失能量表檢測受試者的疼痛及日常功能，足部形態量測則包含舟狀骨滑落測試及足部姿態指數等量測，而地面反作用力的力學分析則為靜止站立 60 s 及以自然速度行走 6 m。下背疼痛評估於治療前及治療 1 個月後各測量一次，並以配對 t 檢定檢測治療 1 個月後的改善情形。而其他評估參數都在腿長調整前、調整後立即、及調整後 1 個月等 3 個時間點進行量測，符合常態分佈的連續數資料以重複量測變異數分析，而非常態分佈之連續數資料或序列性資料則以傅來德曼檢定分析，足部姿態測試則以列聯表分析及費雪精確檢定檢測在 3 個時間點之間足型分布的差異。所有統計顯著水準皆訂在α= 0.05， 而檢定力則訂在 0.8。

本研究主要結果為：（一）以雷射測距計測量腿長具有良好的效度及信度；效度方面，皮爾森相關係數於兩腿皆大於 0.96；而信度方面，ICC(3,3)值皆大於 0.99測量標準誤皆小於 0.2 cm；（二）慢性下背痛在腿長調整介入 1 個月之後有顯著改善；（三）於調整結構性腿長不等後，長腳內旋在統計上有顯著的改善，但效應值在低度與中度之間；（四）靜止站立時，治療前長腳受力較多的受試者在治療後兩腳垂直受力量趨於對稱，而治療前短腳受力較多之受試者其在治療後受力情形則無明顯改變。

此結果顯示腿長調整能夠減輕下背疼痛、改善功能，但無法改變足型。在力學參數方面，雖未能完全解釋臨床觀察，但靜止站立時兩腳承重方式可提供評估腿長調整後雙足對稱承重的依據。此外，利用雷射量測計進行腿長測量為具效度及信度之新方法，未來可在臨床上推廣。未來研究方向可進一步探討腿長調整的改變機轉。

Many musculoskeletal symptoms are highly correlated with leg length discrepancy (LLD), which may be related to asymmetric loading on weight-bearing joints and malalignments of the lower extremities. Leg length adjustment has been reported effective on relieving clinical symptoms; however, its mechanism is still unclear. The purpose of this research was to explore the feasibility of measurement of leg length using a laser distance meter, to determine the effect of leg length adjustment on pain relief at low back, pronation control of the long leg, kinematic changes in the feet for people with anatomical LLD. Four study objectives were developed: 1) to examine the validity and reliability of measurement of leg length using a laser distance meter, 2) to examine the effect of leg length adjustment on pain status and daily functions, 3) to examine the effect of leg length adjustment on controlling excessive pronation of the long leg, and 4) to examine the effect of leg length adjustment on the kinetic variables of ground reaction force.

The present research was designed as a convenient sampling, prospective, quasi-experimental, and pretest/posttest design. There were 2 parts in this research: 1) validity and reliability tests of measurement of standing leg length using a laser distance meter and 2) the effect of leg length adjustment on pain relieving, foot pronation controlling, and related kinetic changes in people with anatomical LLD. For the validity test, standing leg length was obtained through both pelvic radiography and the laser distance meter in 10 healthy male adults. The results were analyzed using Pearson’s correlation coefficient. For the reliability test, 15 healthy adults received measurements of standing leg length twice using a laser distance meter by the same rater on the same day. Intraclass correlation coefficient (ICC(3,3)) and standard error of measurement (SEM) was calculated to present intrarater reliability. Another 30 adults with anatomical LLD were recruited for the second part of the research. The visual analog scale and modified Oswestry Disability Index before and 1-month after intervention were compared using the paired t test, respectively. All participants received the navicular drop test, Foot Posture Index (FPI), quiet stance for 60s, and level walking for 6 m at pre-, immediate after, and 1-month after leg length adjustment. ANOVA with repeated measures or Friedman test was calculated to compare the differences among 3 time points. Crosstable analysis with Fisher’s exact test was calculated for FPI. The significant level was set at α = 0.05 while the power was at 0.8.

The main results of the present research were: 1) using the laser distance meter to measure LLD is valid (r>0.96) and reliable (ICC(3,3) >0.99 and SEM <0.2 cm), 2) the pain status and daily function significantly improved after 1-month intervention, 3) there was a significant decrease in the subtalar pronation of the long leg after 1-month intervention but the effect size was between small and median level only, and 4) more symmetric force distribution was noted at quiet stance after intervention in the participants with more weight on the long leg but not for those with more weight on the short leg.

These results concluded that leg length adjustment relieved back pain and improve daily function successfully but failed to alter the foot type. Although the kinetic variables did not completely explain the effect of intervention, the initial weight bearing pattern at stance affected the results of symmetric wearing bearing pattern after intervention. The laser distance meter was an alternative tool to measure leg length, which presented an excellent validity and reliability, which is a useful clinical tool. All of the above findings give an insight that leg length adjustment can control clinical symptoms which result from anatomical LLD, but the actual mechanism is still further studied.