联合前倾角技术在成人发育性髋关节发育不良全髋关节置换术中的应用

目的探讨联合前倾角技术在成人发育性髋关节发育不良全髋关节置换术中应用的可行性及临床价值。方法回顾性分析自2016-09—2018-06采用联合前倾角技术行全髋关节置换术治疗的31例(36髋)成人发育性髋关节发育不良,比较手术前后髋臼前倾角、股骨前倾角、联合前倾角及髋关节功能Harris评分。结果31例均获得12个月以上随访。术后骨盆正位及髋关节侧位X线片显示假体位置及对应关系良好,无假体松动、下沉,无脱位表现。末次随访时所有患者步态均明显改善,髋部疼痛均消失,仅2例轻度跛行。术后髋臼前倾角、股骨前倾角、联合前倾角较术前明显减小,末次随访时髋关节功能Harris评分较术前明显增加,差异有统计学意义(P<0.05)。结论联合前倾角技术应用于成人发育性髋关节发育不良全髋关节置换术对于指导合适假体的选择、设计以及确定合适的髋臼前倾角、股骨柄前倾角具有重要意义,良好的联合前倾角能够有效预防术后假体脱位的发生。     

成人常见髋关节疾病双侧髋关节解剖参数的研究

目的探讨行全髋关节置换术中利用对侧相对正常髋关节的解剖参数作为模板重建患侧髋关节的准确性。 方法选取2019年9月至2020年12月于大连医科大学附属第一医院关节外科行首次单侧全髋关节置换术的患者作为研究对象。纳入标准：患侧诊断为髋关节骨关节炎、股骨头坏死或髋关节发育不良Crowe Ⅰ型；对侧髋关节形态不影响测量。排除标准：患侧髋关节既往手术史；畸形严重影响测量；髋关节发育不良Crowe Ⅱ型及以上。最后共纳入82例患者，其中33例男性，49例女性，年龄范围29~74岁。根据患者X线及CT影像数据，分别测量患者患侧及对侧髋臼前倾角、髋臼外展角、股骨前倾角、颈干角以及股骨偏心距，并计算其各自的联合前倾角。运用t检验、Pearson相关性分析等统计学方法分析双侧髋关节解剖参数的对称性。 结果对股骨头坏死及髋关节骨关节炎患者来说，除双侧股骨偏心距患侧小于对侧外(t＝0.523，P <0.05)，余双侧髋关节解剖参数包括髋臼前倾角、髋臼外展角、股骨前倾角、联合前倾角及颈干角的差异均无统计学意义(均为P>0.05)。Pearson相关性分析显示股骨头坏死及骨关节炎患者股骨偏心距的不对称性与颈干角有相关性(r＝-0.519，P<0.001)，颈干角的不对称性与股骨前倾角(r＝0.303，P＝0.041)以及股骨偏心距有相关性，联合前倾角的不对称性与髋臼外展角(r＝0.311，P＝0.035)、颈干角(r＝0.049，P＝0.032)有相关性。Crowe Ⅰ型髋关节发育不良患者的髋臼前倾角(t＝2.081，P＝0.045)、股骨偏心距(t＝3.934，P<0.001)患侧小于对侧，颈干角患侧大于对侧(t＝3.792，P＝0.001)；而双侧髋臼外展角、股骨前倾角、联合前倾角差异均无统计学意义(均为P>0.05)。Pearson相关性分析发现股骨偏心距的不对称性与颈干角(r＝-0.709，P<0.001)、股骨前倾角(r＝-0.349，P＝0.037)有相关性。Crowe Ⅰ型髋关节发育不良患者的股骨偏心距小于股骨头坏死患者或髋关节骨关节炎患者，而髋臼前倾角、髋臼外展角、颈干角大于后者。 结论对于股骨头坏死患者及髋关节骨关节炎患者来说利用对侧肢体作为模板重建患侧髋关节是可行的。而Crowe Ⅰ型髋关节发育不良患者双侧髋关节解剖形态差异较大，对这类患者的全髋关节置换术需个体化。     

Prediction of Postoperative Stem Anteversion in Crowe Type II/III Developmental Dysplasia of the Hip on Preoperative Two-Dimensional Computed Tomography

BackgroundPreoperative planning is fundamental for total hip arthroplasty. This study investigated the optimal femoral neck level for measuring femoral anteversion to predict postoperative stem anteversion in developmental dysplasia of the hip and determined the predictive role of average anteversion based on the sagittal 3-point fixation.MethodsSixty-two Crowe type II/III dysplastic hips that underwent total hip arthroplasty were retrospectively analyzed. Preoperative and postoperative anteversion was measured via 2-dimensional computed tomography. Anterior and posterior cortex anteversions were measured at 6 levels of the proximal femur. Femoral anteversion at each level was calculated. Average anterior (lesser trochanter) and posterior cortex anteversions (femoral neck) were calculated based on the sagittal 3-point fixation.ResultsFrom the lesser trochanter to head-neck junction, femoral anteversion decreased gradually from more to less than stem anteversion. For hips with femoral neck height ≥10 mm, femoral anteversion at the 10-mm level above the lesser trochanter proximal base showed no significant difference with stem anteversion, with a good correlation for the single-wedge and an excellent correlation for the double-wedge stem. Average anterior (lesser trochanter proximal base) and posterior cortex anteversions (femoral neck at 10 mm above the lesser trochanter proximal base) showed no significant difference from stem anteversion, with excellent correlations.ConclusionFor Crowe type II/III hips with femoral neck height ≥10 mm, the 10-mm level above the lesser trochanter proximal base is an optimal choice for measuring femoral anteversion to predict postoperative stem anteversion. The average of anterior cortex anteversion at the lesser trochanter and posterior cortex anteversion at the femoral neck has a predictive role.     

Combined anteversion technique reduced the dislocation in cementless total hip arthroplasty

Purpose

The combined anteversion (CA) technique is a method in which the cup is placed according to the stem anteversion in total hip arthroplasty (THA). We examined whether the CA technique reduced the dislocation rate, and the distribution of CA with the manual placement of the cup.

Methods

We retrospectively reviewed 634 hips in 579 patients with primary cementless THA. In 230 hips using the CA technique [CA(+)], a CA of 50 ± 10° was the aim. In the remaining 404 hips [CA(−)], the cup was first placed targeting 20° of anteversion. The post-operative CA was measured using the computed tomography (CT) images in 111 hips.

Results

One hip (0.4 %) had a dislocation in the CA(+) group, whereas ten hips (2.5 %) had a dislocation in the CA(−) group. A multivariate analysis showed that primary diagnosis, head size and CA technique significantly influenced the dislocation rate. Patients in the CA(−) group were 5.8 times more likely to have a dislocation compared to the CA(+) group. In the 111 hips with CT images, 81 hips (73.0 %) achieved the intended CA.

Conclusions

Although the manual placement of the cup resulted in 27 % of outliers from the intended CA, the CA technique significantly reduced the dislocation after primary THA.     

Can we trust combined anteversion and Lewinnek safe zone to avoid hip prosthesis dislocation?

IntroductionDislocation is one of the most common complications after primary total hip arthroplasty (THA). Combined anteversion (CA) is currently considered one of the most important measures of stability for THA. Thus, the aim of this study is to determine the association between a correct CA after THA and hip prosthesis dislocation, and to analyze the reliability of the Lewinnek safe zone parameters.Material and methodsThis is a non-interventional retrospective study, carried out at a tertiary hospital in Spain. 2489 primary THA in 2147 patients between January 2008 and December 2014 were identified. Clinical, biological and radiographic data, including cup inclination and cup and femoral anteversion, were analyzed of all patients who developed a hip prosthesis dislocation.ResultsThirty-four patients met the eligibility criteria to be analyzed. In 73.5% (25/34) of cases, acetabular anteversion (AV) was correct, with a mean AV of 15.1° ± 9.4°. Femoral anteversion (FA) was considered correct only in 38.2% (13/34) of the dislocated THA, with a mean FA of 8.4° ± 17.2°. Sixteen of these 34 patients (47.0%) presented a correct CA, with a mean CA of 24.2° ± 21.0°. Nineteen hips (55.8%) were within the Lewinnek safe zone. Moreover, eleven patients (32.3%) developed a dislocation even though components were within the Lewinnek safe zone and presented a correct CA.ConclusionOur findings suggest that even when the THA components are positioned within a correct CA and in the Lewinnek safe zone, hip prosthesis dislocations can occur in a not inconsiderable percentage of the cases. Thus, further radiological and clinical analysis should be done to identify potential reasons for hip prosthesis dislocation.     

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。     

Anteversion of the acetabular component aligned with the transverse acetabular ligament in total hip arthroplasty

In total hip arthroplasty (THA), accurately positioning the cup is crucial for achieving an adequate postoperative range of motion and stability. For 47 THA cases in which the inferomedial rim of the cup had been positioned parallel to the transverse acetabular ligament, we retrospectively performed the measurements of the radiographic cup anteversion angle relative to the anterior pelvic plane using 3-dimensional reconstruction computed tomography. The mean anteversion angle was 21.2°, with no significant difference detected in mean cup anteversion between the dysplastic hip group (15 hips) and the control group (15 hips). We suggest that the transverse acetabular ligament is a practical anatomical landmark for determining cup anteversion in THA for both dysplastic and nondysplastic hip cases.     

液晶数字显示角度仪在全髋关节置换术中的应用价值

目的:探讨在全髋关节置换术中使用液晶数字显示角度仪控制前倾角的应用价值。方法:回顾分析自2018年1月至2019年12月83例行初次全髋关节置换术的患者,其中男28例,女55例;年龄42~81(70.4±7.9)岁。股骨颈骨折63例,股骨头缺血性坏死20例。所有患者术中使用液晶数显角度仪控制髋臼杯假体的前倾角,术后采用CT扫描,测量髋臼杯的前倾角,两者进行比较,了解使用液晶数显角度仪的准确性。结果:术后CT测量提示患者的髋臼前倾角均位于Lewinnek提倡的安全区内,术中使用液晶数显角度仪测量髋臼杯的前倾角度中位数为14.20°(12.80~15.40)°,术后CT扫描测量的髋臼杯的前倾角中位数为14.20°(13.40~15.50)°,两者比较差异无统计学意义(Z=-1.725,P=0.085)。结论:应用液晶数显角仪器对术中控制髋臼杯的前倾角是一种准确可靠的方法,具有良好的辅助参考价值。     

先天性髋脱位髋臼前倾角的CT测量

目的 探讨先天性髋脱位髋臼前倾角的变化。方法 对18例先天性单侧髋脱位患儿作CT检查，比较其侧与健侧的髋臼前倾角；18例患儿均做手术切开复位，对其中6例患儿术后半年作CT随访，比较其手术前后髋臼前倾角的变化。结果 患侧的髋臼倾角与健侧比较，差异无显著性。手术可改变髋臼前倾角，部分会至异常范围。结论 先天性髋脱位的髋臼前倾角与正常相似，在手术复位过程中髋臼前倾角会有改变。     

Midterm Results of Hybrid Total Hip Arthroplasty for Treatment of Osteoarthritis Secondary to Developmental Dysplasia of the Hip-Chinese Experience

This study was designed to evaluate the midterm results of hybrid total hip arthroplasty in a consecutive series of 45 Chinese patients with osteoarthritis secondary to dysplastic hip. The average follow-up was 6.6 years. A total of 24 hips were classified as dysplasia, 20 hips as low dislocation, and 13 hips as high dislocation. The preoperative Harris score was 46.19 ± 18.01, which improved to 91.78 ± 3.52 at the final follow-up. The rate of polyethylene liner wear was 0.27 mm/y. Osteolysis was identified around 5 acetabular components and 13 femoral components. With the use of loosening or revision as the end point for failure, the survival rate was 1.0. We suggest that hybrid total hip arthroplasty in Chinese developmental dysplasia of hip patients has favorable results at midterm follow-up, even though their lifestyle includes more deep flexion of the hip. There is no significant difference of postoperative Harris score with increasing severity of dysplasia.     

全髋翻修术后假体脱位的预防

目的：探讨采用后方关节囊重建方法对行后外侧入路全髋翻修术后假体脱位的防治作用。方法：本组45例（47髋）经后外侧入路行全髋翻修术的患者，男20例，女25例；平均年龄65岁（55-78岁）。术中将后方关节囊与外旋肌群分别重建固定于前上方原先切开的关节囊断端和大转子顶端的软组织处，回顾性分析术后假体脱位率及脱位的风险因素。股骨假体和髋臼假体均翻修29例（31髋），更换内衬5例（5髋），髋臼、股骨翻修的分别是10例（10髋）和1例（1髋）。第1次翻修的有29例（30髋），第2次翻修的有15例（16髋），第3次翻修的有1例（1髋）。X线评估包括翻修前后下肢长度，髋臼位相，股骨偏心距、前倾角和假体松动。临床功能评价采用Harris评分。结果：45例均获随访，平均随访时间2．7年，除1例感觉前方不稳外，无髋关节感染及脱位发生，该例X线片示髋臼假体过度前倾但无脱位发生。术后所有患者双下肢基本等长，髋臼外展角及前倾角、股骨偏心距和前倾角基本恢复至初次手术前水平。髋臼、股骨假体发生松动各1例。髋关节功能Harris评分由术前平均（49.13±15．53）分升至末次随访的平均（83．59±6.93）分（P〈0．05）。按Harris功能评分标准：优36髋，良5髋，可5髋，差1髋。结论：在假体安放正确、软组织张力恢复满意基础上，后方关节囊及外旋肌群重建有助于降低后外侧入路全髋翻修术后假体脱位的发生率。     

伴腰椎退变性后凸畸形的人工全髋关节置换安放髋臼假体前倾角的策略

目的:探讨伴腰椎退变性后凸畸形患者行人工全髋关节置换时如何更合理地安放髋臼假体的前倾角。方法:纳入2017年12月至2019年10月行人工全髋关节置换术的患者122例,均伴腰椎退变性后凸畸形,分为试验组和对照组,各61例。试验组男25例,女36例;年龄中位数67.0岁;病程中位数46.0个月;术中根据骨盆前平面支架,按不同类型,设置安装髋臼前倾角的功能性骨盆平面。对照组男27例,女34例;年龄中位数67.0岁;病程中位数42.0个月;对照组以传统的方法设定前倾角。术后随访3个月,记录两组患者手术时间、术中出血量,统计3个月内感染脱位发生,记录手术前和术后3个月Harris评分,测量术后3个月患者站立位功能性前倾角。结果:试验组和对照组手术时间、术中出血量比较差异无统计学意义(P=0.918,0.381);术后3个月内两组均无感染;对照组1例髋关节脱位,试验组无脱位。手术前后Harris评分比较差异无统计学意义(P>0.05)。3个月后复查骨盆站立位X线片示:髋臼假体功能性前倾角在安全区外的患者数量试验组比对照组少(P=0.048);并且试验组在15°～20°范围内更集中(P<...     

Evaluation of the hip center in total hip arthroplasty for old developmental dysplasia

We describe the problems with positioning the hip center according to the severity of dislocation in 97 cementless total hip arthroplasty for developmental dysplasia of the hip. The mean location of the hip center from the interteardrop was 30.4 +/- 8.7 mm horizontally and 23.4 +/- 5.4 mm vertically. The presence of a limp correlated with a superior placement of the cup. Four cups were revised, 2 of which with a significant high hip center. The survival rate of the acetabular component was 95% at 12 years. Craniopodal repositioning was easy in class 1. In class 2, the cup was the largest. In class 3, the greatest variations of the hip center were found. In class 4, the smallest implants were necessary for positioning in the true acetabulum.     

成人DDH患者保髋手术失败后的THA疗效分析

目的回顾性分析保髋手术治疗失败后的成人发育性髋关节发育不良患者再次行全髋人工关节置换术的中期疗效。方法选择2014年1月至2019年1月收治的22例(30髋)保髋手术失败后行全髋人工关节置换术(total hip arthroplasty,THA)的发育性髋关节发育不良患者作为研究对象,其中男7例,女15例;行保髋手术时年龄1~18岁,平均(7.9±3.4)岁;行THA时年龄22~63岁,平均(34.2±11.2)岁;单髋14例,双髋8例,左髋16侧,右髋14侧。手术前后采用Harris髋关节评分系统及疼痛视觉模拟评分法(visual analogue score,VAS)进行评价,并对手术前后的X线片进行分析。结果本研究病例全髋人工关节置换术后平均随访时间为(30.5±18.5)个月。全髋人工关节置换术后,Harris总评分从术前的平均(38.7±10.6)分提高至末次随访时的(89.4±9.7)分,差异有统计学意义(t=19.67,P<0.001),且患者的疼痛、行走、功能、活动度等各项指标的术后评分均高于术前且差异有统计学意义;疼痛VAS评分由术前的平均(7.9±0.9)分降低到末次随访时的(1.4±1.0)分,差异有统计学意义(t=30.67,P<0.01);患者双下肢长度差异由术前的平均(3.32±0.51)cm降低到术后(0.71±0.33)cm,差异有统计学意义(t=14.01,P<0.001)。所有患者均无发生手术切口及假体周围感染、假体松动、髋关节脱位、血管神经损伤、深静脉血栓及异位骨化等术后并发症,仅2例患者术中出现股骨近端纵行劈裂。结论保髋手术失败后的成人发育性髋关节发育不良患者行全髋人工关节置换术可获得满意的中期疗效。     

Crowe Ⅱ/Ⅲ型发育性髋关节发育不良股骨近端形态学变化及其对全髋关节置换术的意义

目的分析CroweⅡ/Ⅲ型发育性髋关节发育不良股骨近端的形态变化及其对全髋关节置换术的影响。方法将14例（15髋,CroweⅡ型9髋,CroweⅢ型6髋）成人CroweⅡ/Ⅲ型发育性髋关节发育不良继发骨性关节炎患侧股骨设为治疗组,男2例,女12例;年龄35～61岁。所有患者均未行矫形治疗。15例（15髋）单侧发育性髋关节发育不良患者的健侧股骨为对照组,男3例,女12例;年龄35～57岁。其中12例为治疗组单侧脱位,3例为单侧CroweⅠ型髋关节发育不良。对股骨进行CT扫描,测量股骨头高度（height of centre of femoral head,HCFH）、峡部位置（isthmus position,IP）、颈干角（neck-shaft angle,NS）、股骨前倾角和髓腔闪烁指数及髓腔宽度等参数,并进行统计学分析。结果治疗组和对照组的HCFH分别为50.1±6.7mm和50.1±7.4mm,IP分别为107.4±21.5mm和108.7±18.1mm,比较差异均无统计学意义（P〉0.05）。NS分别为138.3±10.0°和126.7±5.7°,前倾角分别为36.5±15.9°和18.8±5.4°,髓腔闪烁指数分别为4.47±0.40和5.01±0.43,两组比较差异有统计学意义（P〈0.05）。髓腔宽度方面,治疗组在小转子中点上2cm和小转子中点下4cm的内外侧和前后侧宽度均较对照组变小,比较差异有统计学意义（P〈0.05）;两组在峡部水平的髓腔宽度比较差异无统计学意义（P〉0.05）。结论行CroweⅡ/Ⅲ型发育性髋关节发育不良全髋关节置换术时,术前应评估股骨近端的形态学变化,选择直型较小号的股骨假体,术中放置股骨假体于合适的前倾位置。     

螺旋臼全髋关节置换术治疗发育性髋关节发育不良

目的探讨使用螺旋臼假体治疗发育性髋关节发育不良（DDH）继发骨性关节炎患者的临床疗效。方法自2003年5月至2007年12月，使用Zweymaller螺旋臼假体治疗40例（43髋）DDH继发骨性关节炎患者，其中男6例（6髋），女34例（37髋），平均年龄47．6岁（22～70岁）；单侧37例，双侧3例；Crowe分型：Ⅰ级6例，Ⅱ级24例，Ⅲ级10例，Ⅳ级3例。平均随访24．6个月，术前Harris评分最高61分，最低22分，平均43．5分。结果所有患者术后疼痛基本消失，双下肢长度差异平均1．2cm，2例术后出现股神经损伤症状，术后6个月症状基本消失，Harris评分最高97分，最低62分，平均85．3分。结论使用Zweymtiller螺旋臼假体治疗DDH继发骨性关节炎的患者，可以达到良好的恢复关节功能的临床疗效，手术不需大块植骨和骨水泥，初期临床效果满意。     

全髋关节置换结构性植骨治疗髋臼发良不良伴股骨头坏死

目的：评价全髋关节置换、结构性植骨治疗髋臼发育不良伴股骨头坏死的近期手术效果。方法：对9例髋臼发育不良伴股骨头坏死患者行全髋关节置换、结构性植骨术的治疗，髋臼杯置于真臼，之后行髋臼结构性植骨。结果：平均随访3．5年，除1例患者夜间睡眠时发生髋关节后脱位，其余病例均未出现脱位。术后3个月X线片提示结构性植骨块愈合良好，假体无移位，患髋活动灵活。结论：全髋关节置换、结构性植骨治疗髋臼发育不良伴股骨头坏死近期手术效果良好。     

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.     

Hip Abduction Can Be Considered the Sole Posterior Precaution Strategy to Lower the Rate of Impingement After Posterior Approach Total Hip Arthroplasty With Large Femoral Head: A Computer Simulation Study

BackgroundStudies suggest that posterior hip precautions are unnecessary after total hip arthroplasty; however, many surgeons and patients choose to follow these precautions to some extent. In this study, we hypothesized that 20° of hip abduction would be sufficient to prevent impingement and dislocation in motions requiring hip flexion when using larger prosthetic heads (≥36 mm) when the acetabular implant is placed within a reasonable orientation (anteversion:15-25° and inclination: 40-60°).MethodsUsing a robotic hip platform, we investigated the effect of hip abduction on prosthetic and bony impingement in 43 patients. For the flexed seated position, anterior pelvic tilt angles of 10 and 20° were chosen, while anterior pelvic tilt angles of 70 and 90° were chosen for the bending forward position. An additional 10° of hip external rotation and 10 or 20° of hip internal rotation were also added to the simulation. One hip received a 32-mm head; otherwise, 36-, 40-mm, or dual-mobility heads were used. The study power was 0.99, and the effect size was 0.644.ResultsIn 65% of the cases, bone-bone impingement between the calcar and anterior-inferior iliac spine was the main type of impingement. The absolute risk of impingement decreased between 0 and 16.3% in both tested positions with the addition of 20° hip abduction.ConclusionWith modern primary total hip arthroplasty stems (low neck diameter) and an overall acceptable cup anteversion angle, small degrees of hip abduction may be the only posterior hip precaution strategy required to lower the risk of dislocation among patients. Future studies can potentially investigate the concept of personalized hip precautions based on preoperative computer simulations, utilized implants, hip-spine relations, and final implant orientation.     

Influence of component positions on dislocation: computed tomographic evaluations in a consecutive series of total hip arthroplasty

Component positions in a consecutive series of total hip arthroplasty through a posterolateral approach without capsular and external rotator repair, using the same prosthesis type, head size, and liner, were evaluated using computed tomography, and correlation with occurrence of postoperative dislocation was assessed. The 9 hips with posterior dislocation had significantly lower cup anteversion than the 181 hips without dislocation. Seven (78%) of the 9 hips with posterior dislocation had cup anteversion <20 degrees, irrespective of stem anteversion. These findings suggest that among variables of component positions, cup anteversion is one of the important factors for risk of dislocation, and that intentionally placing the cup at low anteversion to compensate for high femoral neck anteversion may predisposes the hip to postoperative dislocation.