接受骨盆切骨術後髖外翻之單側發展性髖關節發育不良患者之步態分析

Abstract

利用骨盆切骨術治療發展性髖關節發育異常(DDH)被認為可以預防股骨頭缺血性壞死、髖臼發育不良以及退化性關節炎等嚴重併發症。骨盆切骨術因具有可調整髖臼方向、髖臼容積與髖臼覆蓋方向之優點，使得髖關節獲得較佳的幾何形狀與位置而被用於DDH的早期治療。然而另有文獻指出患者髖關節在經骨盆切骨術復位後仍有較高的機會形成關節的早發性退化以及罹患股骨頭缺血性壞死。已有學者研究證實此併發症的產生與走路時髖關節的異常受力有關，因此，在恢復髖關節的正常幾何形狀以及功能的同時，減少髖甚至於膝關節的作用力對於防止退化性疾病是非常重要的。更有甚者，發展性髖關節發育不良的病人，其股骨頸幹的角度常會隨著身體發展而逐漸增加，然而，即便經過骨盆切骨術，仍究有8%的患者會有殘餘髖外翻(Coxa valga)的情形。過大的股骨頸幹角，會造成走路時雙側步態上的不對稱，下肢肌肉用力方式的改變，並且也許會有更多能量的消耗。另外，髖外翻的嚴重程度與髖關節作用力大小以及方向具高度相關性，早已被學者提出。 因此，本研究的出發點為了解發展性髖關節發育異常患者在進行骨盆切骨術後，髖外翻與正常股頸幹角(Femoral neck-shaft angle)患者以及正常受試者在走路時下肢的歩態差異。研究中徵召24位接受骨盆切骨術治療單側DDH的女性，依其股頸幹角的角度分為正常股頸幹角組(平均年齡:12.63歲，平均身高:149.71公分，平均體重:41.96公斤、BMI:18.60)以及髖外翻組(平均年齡:11.51歲，平均身高:144.91公分，平均體重: 38.95公斤、BMI:18.34)另有12位做為控制組的健康女孩(平均年齡: 12.5歲，平均身高: 148.7公分，平均體重: 41公斤，身體質量指數(Body mass index, BMI)):24.29)，藉由三維動作分析，分析運動學參數如關節角度(Joint angles)以及力動學參數如關節軸向作用力(Joint axial force)、地面反作用力(Ground reaction force)、關節軸向作用力以及地面反作用力之負載速率(Loading rate)和卸載速率(Unloading rate)以及關節力矩(Joint moment)等，還有空間-時間(Spatial-temporal)參數變化，以了解不同族群的病患於走路時的動作特徵、動作策略，以及代償性動作表現。結果發現於正常股頸幹角組可以發現較為無力的髖屈肌、膝伸肌以及髖外展肌之歩態，導致走路時較多的骨盆前傾、上提以及雙側膝關節彎曲。而於髖外翻組則可以發現下肢髖、膝關節軸向力峰值增加以及其負載速率上升等受力異常的情形以及骨盆前傾、上提和轉向至對側的情況。骨盆切骨術後患側較容易痠痛且無力的情況常常是病患的主訴，而早發性退化性關節炎以及股骨頭缺血性壞死亦是常見骨盆切骨術後的後遺症，因此針對術後頸幹角不同的病人，應該給予不同的復健、矯具等諮詢建議以及後續可能的手術治療對策，以保護髖關節不會一直承受過高的負載而引發後續的股骨頭缺血性壞死或早發性退化的問題。

Therapeutic use of pelvic osteotomy in developmental hip dysplasia abnormalities (DDH) is thought to prevent avascular necrosis, acetabular dysplasia, degenerative arthritis and other serious complications. While pelvic osteotomy can re-orient the acetabulum or change the acetabular capacity with alternated coverage direction to get a better hip geometry and location. It’s widely used in the early treatment of DDH. However, previous studies show there is a higher chance of developing hip avascular necrosis and premature osteoarthritis after pelvic osteotomy. Scholars have confirmed such complications were closely related to abnormal loadings at hip joint while walking. Therefore, it is very important to reduce joint reaction forces while restoring the normal geometric shape and functions of the hip joint in order to prevent degenerative diseases. Moreover, the femoral neck shaft angle often gradually increase with age in developmental hip dysplasia patients. Even after pelvic osteotomy, 8% of patients still suffer from coxa valga. Worsening hip valgus angle may result in asymmetric gait pattern, different muscle contraction pattern and maybe more energy consumption. Otherwise, it was proposed by other scholars that different hip valgus angles are highly correlated to different magnitudes and directions of joint force. Therefore, the starting point of this study is to understand the differences of gait patterns in patients with coxa valga, normal femoral neck-shaft angle and normal control after pelvic osteotomy. Twenty-four females who had received pelvic osteotomy for unilateral DDH were recruited, twelve of them was classified as normal neck-shaft angle group(Average age:12.63y/o，average height:149.71cm，average body weight:41.9kg、(Body mass index, BMI):18.60), others are classified as coxa valga group(Average age:11.51y/o，average body height:144.91cm，average weight: 38.95kg、BMI:18.34) ,and Twelve age-matched healthy controls(Average age: 12.5y/o，average height: 148.7cm，average weight 41kg， BMI:24.29) were recruited. Three-dimensional motion analysis is used to analyze kinematic parameters such as joint angles and kinetic parameters like joint axial forces, ground reaction forces, loading rate and unloading rate of axial joint forces and ground reaction force, joint moments, etc. Spatial-temporal parameters are also included. These parameters may help us to understand the movement characteristics, action strategies, and compensatory action performance in different groups of patients during level walking. Results show that normal neck-shaft angle group has more pelvis anterior tilt, affected side hiking and bilateral knee flexion. Coxa valga group has more pelvis anterior tilt, affected side hiking and pelvis rotation to contralateral side. Peak joint axial force has significant increase in both hip and knee joints of affected side were also found in coxa valga group. Affected side soreness and muscle weakness are always complained by patients, therefore, different treatment strategies should be considered for different group to prevent common sequelae such as avascular necrosis and premature osteoarthritis of patients after pelvic osteotomy.