髋关节假体安装参数的计算机模拟研究

目的 研究不同颈干角股骨假体在前倾角变化时获得理想髋关节活动度所需要的髋臼安装参数.方法 建立人工全髋关节三维计算机模型,髋臼杯假体采用半球形,臼杯直径480mm,颈干角分别为127°、131°和135°.股骨假体前倾角变化范围为0°~30°,臼杯假体俯倾角变化范围为30°~60°、前倾角变化范围为0°~40°.每变化5°重复一次髋关节在6个方向(屈曲、后伸、内收、外展、内旋、外旋)的活动,选出符合最佳髋关节活动度的假体安装参数.采用SAS 6.12统计学软件对数据进行分析.结果 颈干角分别为127°、131°和135°的假体,其最佳的臼杯俯倾角安装位置分别为45°、40°和35°;在活动满足后伸>40°、内收>50°、外展>50°、内旋>80°、外旋>40°的条件下,髋关节最大屈曲度分别为135.64°±3.45°、126.00°±3.57°和118.29°±3.29°;臼杯假体前倾角(Y)和股骨假体前倾角(X)的关系分别为Y+0.69×X=36.93°,Y+0.71×X=37.10°和Y+0.64×X=36.79°.结论 臼杯俯倾角最佳安装位置随着假体颈干角的变大而逐渐变小,髋关节在安全范围可以达到的最大屈髋度数随假体颈干角变大而逐渐减小,股骨假体前倾角度和臼杯前倾角度呈负相关.     

全髋关节置换术中髋臼假体位相的安全范围及杯颈前倾角的优化组合

目的 探讨全髋关节置换术(THA)中髋臼杯的安全范围及杯颈前倾角的优化组合方法. 方法 建立THA三维可视化模型,定义两种髋关节活动度标准:一般标准(髋关节屈曲≥110°、屈曲90°时内旋≥30°、后伸≥30°和中立位外旋≥40°而没有假体撞击)和严格标准(髋关节屈曲≥120°、屈曲90°时内旋≥45°、后伸≥30°和中立位外旋≥40°而没有假体撞击).头颈比变化范围为2.00 ～2.92,股骨假体前倾角变化范围为0～30°,髋臼假体外展角变化范围为10°～60°,髋臼前倾角变化范围为0 ～ 70°,计算满足髋关节两组活动标准、臼杯外展角每变化5°相应的髋臼假体前倾角的安装参数.结果 严格标准下的安全范围较一般标准小,两种标准下的髋臼杯安全范围面积随着头颈比增大而增大.当颈干角为130°时,一般标准和严格标准下髋臼杯前倾角(Y)与股骨假体前倾角(X)的关系分别为Y1=-0.840X1+38.41,Y2=- 1.007 X2 +47.46;允许的最小髋臼外展角(OImin)和头颈比(GR)的关系分别为OImin'1=168.13 GR1-2.504,OImin'2=213.79 GR2-2.272.当颈干角从135°移向130°时,杯安全范围移向杯前倾角较小的区域,面积也有所减小.结论 THA中可以通过增大头颈比来扩大臼杯安放的安全范围.允许的最小髋臼外展角随着头颈比增大而变小,杯前倾角与股骨颈前倾角呈负相关.股骨颈前倾角的增大和颈干角的变小均使得杯安全范围移向杯前倾角较小的区域.     

全髋关节置换后外侧结构重建前后的生物力学变化

目的分析后外侧入路行全髋关节置换（THA）后外侧结构重建前后的髋关节生物力学变化。方法 2012年11月至2013年3月期间,行人工THA手术患者9例10髋,其中股骨头坏死患者3例4髋,发育性髋关节发育不良并骨关节炎患者侧3例3髋（CroweⅠ型2例,CroweⅡ型1例）,股骨颈骨折3例3髋;男4例,女5例;年龄41-75岁,平均59.67岁。常规采用后外侧入路、生物型假体。所有患者均行关节囊及外旋肌群修复,于关节囊及外旋肌群修复前后分别测定髋关节内收、外展0°,屈曲45°和屈曲90°内旋时,关节即将脱位时扭矩的大小,观察股骨大转子后方有无骨折、关节囊及外旋肌群有无撕裂、缝线有无开结及断线、坐骨神经损伤。结果关节囊及外旋肌群缝合前后扭矩有显著增加,屈髋45°时,缝合前扭矩测量为（7.88±5.87）N·m,缝合后扭矩为（14.03±6.81）N·m,差异有统计学意义（P〈0.01）;屈髋90°时,缝合前扭矩测量为（12.22±3.58）N·m,缝合后扭矩为（17.15±5.81）N·m,差异有统计学意义（P〈0.01）。术中出现1例大粗隆后缘骨折,1例后外侧结构缝合打结后,线结松动,1例缝线断裂情况,术后随访3个月,无关节脱位发生,无坐骨神经损伤。结论 THA术中后方关节囊及外旋肌群的修复可显著改善THA术后关节即刻稳定性。     

严重髋关节融合强直畸形的全髋关节置换术

目的探讨采用全髋关节置换术(THA)治疗严重髋关节融合强直畸形的手术方法及临床疗效。方法对48例(57髋)严重髋关节融合强直畸形分次行单侧THA,均采用外侧切口,通过对股骨颈2次截骨后,根据骨盆倾向头侧还是尾侧进行髋臼成形,正确定位臼杯的外展角,根据患侧屈曲畸形情况进行股骨柄和髋臼前倾角的调整。结果术后48例均获随访平均28.5(12~36)个月,1例一侧假体下沉4 mm,1例出现假体周围骨折,1例出现股骨近端劈裂,1例出现坐骨神经的牵拉伤。末次随访时,Harris评分从术前平均16.3分提高到85.6分;髋关节活动度由术前0°提高至术后平均152.5°,其中平均屈髋91.4°;髋关节屈曲畸形程度由术前平均25.6°改善至术后平均5.1°。术后患者髋痛基本消失,术侧步态基本恢复正常,无严重并发症发生。结论严重髋关节融合强直屈髋畸形的THA不能按常规的方式处理,显露出真臼底和根据术前患肢的内旋或外旋程度把握好准确的前倾角、外展角是手术成功的关键。     

全髋置换后修补闭孔外肌对髋关节稳定性的影响

目的 研究闭孔外肌及其覆盖区髋关节囊的解剖特点,探讨髋关节屈曲内旋下闭孔外肌对髋关节的稳定作用.方法 取10具20侧甲醛液固定的成人尸体髋标本,左侧10髋解剖出闭孔外肌,屈曲内旋时触摸体会股骨头对闭孔外肌的膨顶;裸露闭孔外肌区的髋关节,分别测量髋关节屈曲30°、60°、90°和各屈曲角度加内旋15°时股骨头软骨面超出髋臼唇的距离;右侧10髋解剖出髋关节囊,测量后方关节囊各部厚度,观察坐股韧带走行.结果 闭孔外肌是紧贴髋关节囊后下部的唯一肌肉,在髋屈曲内旋时股骨头膨顶闭孔外肌;随着屈曲角度的增大,膨顶程度(后脱位倾向)也加大,同一屈曲角度下内旋比不内旋膨顶程度大.髋后方关节囊的厚度具有不均一性,较薄弱的两部处在闭孔外肌区,坐股韧带主干未经过闭孔外肌区,闭孔外肌区是髋后方关节囊的相对薄弱区.结论 闭孔外肌是髋关节囊后下部唯一的动力抵挡,易诱发后脱位的髋屈曲内旋体位下,抵挡股骨头脱位的主要有闭孔外肌和此肌覆盖区的关节囊,但此区关节囊相对薄弱,因此在全髋置换后应对闭孔外肌进行修补.     

髋臼方位与全髋置换术后脱位的关系

目的研究人工全髋置换术后髋臼方位对髋关节脱位的影响,并为临床提供评价标准。方法测量318例(326髋)X线片的髋臼外展角、前倾角及股骨头旋转中心垂直位置,通过平均2.7年随访来确定上述3因素与术后髋脱位的关系,并进行统计学处理。结果在最近随访时,326髋有10髋发生脱位。外展角≥55°,较<55°脱位发生率有显著性差异;股骨头旋转中心垂直位置≥30mm,较<30mm脱位发生率也有显著性差异;前倾角≥15°和<15°相比,脱位发生率没有显著性差异;前倾角与外展角没有交互作用。结论髋臼方位不当与全髋置换术后的脱位明显相关;外展角<55°,股骨头旋转中心垂直位置<30mm及合适的前倾角可以提供较稳定的髋关节,明显降低术后髋脱位的发生率。     

修复关节囊及外旋肌群对预防全髋关节置换术后关节脱位的作用

目的 探讨采用髋关节后外侧切口进行初次全髋关节置换术(THA)时修复关节囊及外旋肌的作用.方法 2002年1月至2006年6月,初次采用后外侧切口行THA 116例122髋,术中保留后方关节囊及外旋肌群,并且分别将其用疝缝线"8"字直接缝合至股骨大转子(修复组).将修复组THA术后脱位率与同期常规行THA(未修复关节囊及外旋肌,对照组)的255例266髋THA做比较分析. 结果术后6个月内,修复组仅1髋(1/122,0.8%)发生术后早期脱位;对照组则有15髋发生早期脱位(15/266,5.6%),早期脱位率差异有统计学意义(X2=4.914,P=0.027);两组术后6个月均无冉脱位. 结论采用后外侧切口进行THA时修复关节囊及外旋肌群技术能够有效预防术后早期脱位.     

髋臼假体角度与全髋关节置换术后脱位的关系

目的研究人工全髋关节置换术（THA）髋臼假体安装固定角度与术后髋关节脱位的关系。方法在X线片测量236例（248髋）THA术后的髋臼外展角和前倾角,将外展角设定为〈30°、30-50°、〉50°3组,前倾角设定为〈0°、0-25°、〉25°3组。分析以上2个因素与术后髋关节脱位的关系。结果脱位组外展角平均（39±11．88）°,非脱位组为（38．98±8．65）°,两组之间外展角差异无统计学意义（P=0．449）;脱位组前倾角平均（12．33±14．89）°,非脱位组为（13．21±11．52）°,两组之间前倾角差异无统计学意义（P=0．131）°外展角在〈30°、30-50°、〉50°不同范围的脱位率差异无统计学意义（P〉0．05）,前倾角在〈0°、0～25°、〉25°不同范围内的脱位率差异无统计学意义（P〉0．05）。结论髋臼假体外展角在14～58°范围内、前倾角在-15～350范围内与THA术后脱位之间不存在相关性。     

后方关节囊修补预防全髋关节置换术后早期脱位

[目的]探讨加强修补后方软组织预防行后外侧切口首次人工全髋关节置换术后早期脱位的临床疗效和机理。[方法]回顾分析212例首次THA术中缝合后方关节囊与外旋短肌至臀中肌腱性部分的病例术中假体旋转活动度及术后早期脱位率，并与前期行关节囊完全切除的486例作对照分析。[结果]随访6个月～5a（平均3．7a），修补关节囊组仅2髋（0．9％）发生术后早期脱位；对照组发生脱位27髋（5．6％）。两组差异有显著意义（x^2=8．51，P〈0．005）。术中观察显示修补关节囊能够限制髋关节过度内旋20％～50％，阻止股骨头假体在髋臼内衬内的初始滑动。[结论]在假体安放正确基础上，加强修补后方关节囊能够有效预防行后外侧切口首次THA术后早期脱位，机理为关节囊修补后能限制髋关节过度内旋、阻止股骨头假体在髋臼内衬内的初始滑动，并提供了形成致密的假关节囊的生物学基础。     

金对金解剖直径头微创全髋关节置换术治疗高龄股骨颈骨折的近期疗效对照研究

目的探讨金对金解剖直径头和常规小直径头(28mm)全髋关节置换(total hip arthroplasty,THA)微创技术治疗高龄股骨颈骨折患者的临床疗效。方法 2006年1月至2007年12月间因股骨颈骨折在我中心行微创全髋关节置换手术并获得完整资料的高龄(70岁)患者61例61髋,其中采用常规直径头股骨头全髋关节假体(对照组)30例30髋,采用金对金大直径股骨头全髋关节假体(观察组)31例31髋。分析两组术后2周、6周髋关节活动范围,术后2年假体脱位率以及Harris评分结果的差异。结果术后对照组脱位2例6次,观察组0例。观察组的Harris评分优秀率高于对照组;术后2周(除后伸动作外)和6周的髋关节活动度均大于对照组,两组比较,差异有统计学意义(P0.05)。结论采用金对金解剖直径头THA微创技术治疗高龄股骨颈骨折患者,具有术后早期髋关节稳定性提高、主动活动范围增加、术后脱位率降低等优点,近期疗效满意。     

The effect of acetabular cup orientations on limiting hip rotation.

The orientation of the acetabular cup and position of lip augmentation (if present) may improve postoperative total hip replacement stability by decreasing dislocation caused by hip prosthesis impingement during rotation. To determine how these cup parameters affect dislocation, the range and amount of rotation for two standard femoral components was determined in a Sawbones hemipelvis model. The parameters that allowed for maximal range of rotation were a cup angle of inclination between 35 degrees and 45 degrees and cup anteversion between 0 degrees and 10 degrees. Cup anteversion angles greater than 20 degrees and cup angles of inclination greater than 45 degrees significantly limited internal and external rotation, particularly for hip flexion greater than 60 degrees. The position of the cup lip augmentation did not affect the amount of rotation except when the hip was flexed and the lip superiorly oriented. Although there are currently devices to facilitate a particular cup position, hip stem type and orientation are other important factors affecting range of rotation that must be considered.     

A cadaveric study of posterior dislocation after total hip replacement��effects of head diameter and acetabular anteversion

The size of the femoral head and acetabular anteversion are crucial for stability in total hip replacements. This study examined the effects of head diameter and acetabular anteversion on the posterior instability after total hip replacement in an in vivo setting. The acetabular shell was inserted at 0–20° of anteversion at five degree intervals. By using different head sizes (28 mm, 32 mm, 36 mm), the degrees of dislocation were recorded by computer navigation. The 36-mm group consistently showed better stability compared with the 32- and 28-mm groups, regardless of the degree of cup anteversion. Within each group of head size, the hip was significantly more stable when the cup anteversion increased from 0° to 10°. The difference became insignificant when it increased from 15° to 20°.     

The effect of the orientation of the acetabular and femoral components on the range of motion of the hip at different head-neck ratios

BACKGROUND: Prosthetic impingement due to poor positioning can limit the range of motion of the hip after total hip arthroplasty. In this study, a computer model was used to determine the effects of the positions of the acetabular and femoral components and of varying head-neck ratios on impingement and range of motion. METHODS: A three-dimensional generic hip prosthesis with a hemispherical cup, a neck diameter of 12.25 millimeters, and a head size ranging from twenty-two to thirty-two millimeters was simulated on a computer. The maximum range of motion of the hip was measured, before the neck impinged on the liner of the cup, for acetabular abduction angles ranging from 35 to 55 degrees and acetabular and femoral anteversion ranging from 0 to 30 degrees. Stability of the hip was estimated as the maximum possible flexion coupled with 10 degrees of adduction and 10 degrees of internal rotation and also as the maximum possible extension coupled with 10 degrees of external rotation. The effects of prosthetic orientation on activities of daily living were analyzed as well. RESULTS: Acetabular abduction angles of less than 45 degrees decreased flexion and abduction of the hip, whereas higher angles decreased adduction and rotation. Femoral and acetabular anteversion increased flexion but decreased extension. Acetabular abduction angles of between 45 and 55 degrees permitted a better overall range of motion and stability when combined with appropriate acetabular and femoral anteversion. Lower head-neck ratios decreased the range of motion that was possible without prosthetic impingement. The addition of a modular sleeve that increased the diameter of the femoral neck by two millimeters decreased the range of motion by 1.5 to 8.5 degrees, depending on the direction of motion that was studied. CONCLUSIONS: There is a complex interplay between the angles of orientation of the femoral and acetabular components. Acetabular abduction angles between 45 and 55 degrees, when combined with appropriate acetabular and femoral anteversion, resulted in a maximum overall range of motion and stability with respect to prosthetic impingement. CLINICAL RELEVANCE: During total hip arthroplasty, acetabular abduction is often constrained by available bone coverage, while femoral anteversion may be dictated by the geometry of the femoral shaft. For each combination of acetabular abduction and femoral anteversion, there is an optimum range of acetabular anteversion that allows the potential for a maximum range of motion without prosthetic impingement after total hip arthroplasty. These data can be used intraoperatively to determine optimum position.     

Reducing the risk of dislocation after total hip arthroplasty: the effect of orientation of the acetabular component

Malposition of the acetabular component is a risk factor for post-operative dislocation after total hip replacement (THR). We have investigated the influence of the orientation of the acetabular component on the probability of dislocation. Radiological anteversion and abduction of the component of 127 hips which dislocated post-operatively were measured by Einzel-Bild-R?entgen-Analysis and compared with those in a control group of 342 patients. In the control group, the mean value of anteversion was 15 degrees and of abduction 44 degrees. Patients with anterior dislocation after primary THR showed significant differences in the mean angle of anteversion (17 degrees), and abduction (48 degrees) as did patients with posterior dislocation (anteversion 11 degrees, abduction 42 degrees). After revision patients with posterior dislocation showed significant differences in anteversion (12 degrees) and abduction (40 degrees). Our results demonstrate the importance of accurate positioning of the acetabular component in order to reduce the frequency of subsequent dislocations. Radiological anteversion of 15 degrees and abduction of 45 degrees are the lowest at-risk values for dislocation.     

A computer model of the position of the combined component in the prevention of impingement in total hip replacement

Dislocation remains a major concern after total hip replacement, and is often attributed to malposition of the components. The optimum position for placement of the components remains uncertain. We have attempted to identify a relatively safe zone in which movement of the hip will occur without impingement, even if one component is positioned incorrectly. A three-dimensional computer model was designed to simulate impingement and used to examine 125 combinations of positioning of the components in order to allow maximum movement without impingement. Increase in acetabular and/or femoral anteversion allowed greater internal rotation before impingement occurred, but decreases the amount of external rotation. A decrease in abduction of the acetabular components increased internal rotation while decreasing external rotation. Although some correction for malposition was allowable on the opposite side of the joint, extreme degrees could not be corrected because of bony impingement. We introduce the concept of combined component position, in which anteversion and abduction of the acetabular component, along with femoral anteversion, are all defined as critical elements for stability.     

Metal-on-metal hip resurfacing: the effect of cup position and component size on range of motion to impingement

The aim of this dry bone study was to determine the range of hip motion to impingement for different hip resurfacing cup positions and component sizes. The maximum angles of hip flexion, extension, abduction, and adduction were calculated from 3-dimensional coordinates for: 1. Cup inclination of 30 degrees , 40 degrees , 50 degrees , 60 degrees , and 70 degrees with fixed anteversion; 2. Cup anteversion of 0 degrees , 10 degrees , 25 degrees , 35 degrees , and 45 degrees with fixed inclination; and 3. 3 different component sizes on the same size dry bones. An acetabular component inclination of 50 degrees and an anteversion of 25 degrees allowed the most physiologic range of hip motion. A larger-diameter femoral component relative to the native femoral neck diameter resulted in a greater range of hip motion to impingement.     

Analysis of optimal range of socket orientations in total hip arthroplasty with use of computer-aided design simulation

A three-dimensional computer-aided design model of a total hip replacement was used to study the effects of anteversion and abduction of the acetabular component and anteversion and varus-valgus an-gulation of the femoral component on the range of hip flexion and extension that could be obtained without component impingement. Impingement of the component was defined as impingement between the neck of the femoral component and the edge of the acetabular component. To achieve an angle of hip flexion greater than 90° and an extension angle greater than 30° without component impingement, the optimal angulations were found to be between 1 and 30° of anteversion and 30 and 50° of abduction of the acetabular component, as well as 10° of anteversion of the femoral component. When the valgus angulation of the femoral component was reduced from 7 to 0°, the allowable range of flexion without impingement increased under the. same conditions of acetabular-component orientation and femoral-component anteversion. Significant inverse correlations were found between the anteversion angle of the acetabular component and both the lumbar lordosis angle and the sacrohorizontal angle.     

髋臼横韧带定位髋臼假体前倾校正骨盆旋转

目的通过观察后外侧入路全髋关节置换术中骨盆的旋转变化，探讨术中骨盆旋转对髋臼假体前倾角植入的影响，评估使用髋臼横韧带作髋臼假体前倾定位的准确性以及对骨盆旋转角度变化的校正作用。 方法2015年1月至2016年1月河池市第三人民医院关节外科收治的行初次THA的40例44髋的髋关节疾病患者纳入本研究。纳入标准为：初次THA术的患者，术前、术后CT扫描质量符合标准、能确定髋臼解剖前倾角、髋臼假体前倾角的患者。排除标准：髋臼发育不良、强直性脊柱炎、既往有髋关节严重创伤手术史以及翻修术等，术前、术后双髋关节CT扫描，CT横断面上骨盆明显倾斜、两侧髋关节的中心显示明显不在同一层面、难以确定水平线测量前倾角的患者，予以排除。手术均采用侧卧位后外侧入路，切皮前将1枚施氏针以垂直于地面方向打入髂骨嵴，术中髋臼假体的前倾角，以髋臼横韧带为参照标志，通过直接参照或间接参照髋臼横韧带进行髋臼挫磨及安装臼杯，使髋臼假体开口平行韧带进行安放，在此过程中用摄像机记录施氏针相对于地面的角度变化，确定手术过程中骨盆旋转度数，同时测量并记录挫磨髋臼及安放假体时，相对于身体长轴髋臼手术前倾角的数值。术后通过CT测量髋臼假体前倾角，对术中手术前倾角和术后髋臼假体的前倾角、术前髋臼解剖前倾角数据进行t检验分析。 结果术中骨盆旋转发生在本研究中的平均度数为(18±4)°。44个髋关节中，所有的病例都能对髋臼横韧带进行辨认，术中手术前倾角平均为(33±5)°，有93%(41髋)的病例大于Lewinnek提出的"安全区"的前倾角上限25°，余下的7%(3个髋)也全部大于24°。术后CT测量髋臼假体的解剖前倾角为(21±10)°，与术前髋臼解剖前倾角度(19±7)°比较，差异无统计学意义(t＝1.264，P >0.05)。 结论在后外侧入路THA术中，体位改变骨盆前旋转会影响髋臼假体植入的准确性，使用髋臼横韧带作为解剖标志指导髋臼假体前倾角度的植入，可以排除患者体位改变骨盆旋转对前倾角的影响，提高髋臼假体放置的准确性。     

Compliant positioning of total hip components for optimal range of motion.

Impingement between femoral neck and endoprosthetic cup is one of the causes for dislocation in total hip arthroplasty (THA). Choosing a correct combined orientation of both components, the acetabular cup and femoral stem, in manual or computer-assisted implantation will yield a maximized, stable range of motion (ROM) and will reduce the risk for dislocation. A mathematical model of a THA was developed to determine the optimal combination of cup inclination, cup anteversion, and stem antetorsion for maximizing ROM and minimizing the risk for cup-neck impingement. Single and combined hip joint motions were tested. A radiographic definition was used for component orientation. Additional parameters, such as stem-neck (CCD) angle, head-neck ratio, and the design of the acetabular opening, were also considered. The model showed that a maximized and safe ROM requires compliant, well-defined combinations of cup inclination, cup anteversion, and stem antetorsion depending on the intended ROM. Radiographic cup anteversion and stem antetorsion were linearly correlated. Additional internal rotation reduced flexion, and additional external rotation reduced extension, abduction and adduction. The articulating hemispheric surface of acetabular cups should be oriented between 40 degrees and 45 degrees of radiographic inclination, between 20 degrees and 28 degrees of radiographic cup anteversion, and should be combined with stem antetorsion so that the sum of cup anteversion plus 0.7 times the stem antetorsion equals 37 degrees. Final component orientation must also consider cup containment, implant impingement with bone and soft tissue, and preoperative skeletal contractures or deformities to achieve the optimal compromise for each patient.     

Anteversion of the acetabulum and femoral neck in early walking age patients with developmental dysplasia of the hip

Computed tomography measurements were made to quantify the relationship between the anteversion of the acetabulum and femoral neck in 27 early walking age patients (age range; 18-48 months) with developmental dysplasia of the hip. The centre-edge angle and acetabular index were measured in standard pelvis radiographs, and anteversion of acetabulum and femoral neck were measured by use of two-dimensional computed tomography in 25 complete dislocated, 19 subluxated and 10 unaffected hips (a total of 54 hips). The diagnosis of dysplasia, subluxation and complete dislocation of developmental hip dysplasia were determined radiographically using Ishida's criteria. There were statistically significant differences between the three groups for the centre-edge angle, the acetabular index, and acetabulum anteversion. There was no statistically significant difference between the three groups for femoral neck anteversion. The acetabular anteversion was found to be 13.4+/-2.8 degrees (mean+/-SD) in unaffected hips, 16.7+/-1.9 degrees in subluxated hips and 19.8+/-2.5 degrees in complete dislocated hips. There was statistically significant difference between the three groups, with a wide range of acetabular anteversion values noted in all groups (9-26 degrees ). The acetabular anteversion was increased on the dislocated side in each patient and we found no retroverted acetabulum. On the other hand there was no significant difference between the groups with regards to femoral neck anteversion. We conclude that confirming anteversion of the acetabulum and the femoral neck by two-dimensional computed tomography is needed in treatment planning of early walking age patients with developmental hip dysplasia.