Acetabular morphological variation in Asian patients with femoral neck fracture: A three-dimensional CT-based study

AimsThe acetabular morphology varies greatly among individuals, and hypoplasia is more common in Asia than in Europe. Dislocation after bipolar hip arthroplasty (BHA) for femoral neck fracture occurs at a constant rate, and is affected by the acetabular morphology. This study aimed to clarify individual differences in the acetabula of Asian patients with displaced femoral neck fractures.Patients and methodsFifty patients with displaced femoral neck fractures were assessed (50 fractured hips, 50 non-fractured hips). On CT corrected by the anterior pelvic plane, the 100 hips were assessed regarding acetabular coverage (six parameters), acetabular depth (two parameters), and acetabular opening angle (four parameters). Additional parameters related to the fracture and sex were examined. The percentile of each parameter was shown for all hips.ResultsThere was no patient with hip dysplasia defined as superior acetabular sector angle (SASA) less than 110° Compared with men, women had a significantly smaller anterior acetabular sector angle (AASA) (p = 0.016), and significantly larger acetabular inclination angle (p = 0.006) and acetabular index angle (p = 0.034). In the group with a normal SASA, seven hips (7.3%) had an anterior wall defect (AASA<50°) and five hips (5.2%) had a posterior wall defect (posterior acetabular sector angle<90°).ConclusionOlder adults with femoral neck fractures can have anterior wall and posterior wall defects, even if their SASA is normal. Hidden acetabular dysplasia may be related to post-BHA dislocation. So, our results suggest that is important to accurately evaluate the acetabulum of patients with femoral neck fracture before surgery.     

Application of three-dimensional computerised tomography reconstruction and image processing technology in individual operation design of developmental dysplasia of the hip patients

Purpose

Acetabular coverage deficiency displays individual difference among patients with developmental dysplasia of the hip (DDH). Therefore, the correct direction and degree of the acetabular fragment is patient-specific during Bernese periacetabular osteotomy (PAO). This paper introduces a feasible method using 3D computed tomography (CT) and computer image processing technology for customised surgical planning.

Methods

CT data of 96 hips in 60 DDH patients (male 15, female 45; average age/range 30?±?8/14–49 years) and 53 normal hips (male 13, female 37; average age/range 52?±?13/16–69 years) were reconstructed using commercially available software Mimics and Imageware. Geometric parameters of each hip were measured in relation to the anterior pelvic plane after correcting for pelvic tilt and rotation. Deficiency types and degrees of acetabular dysplasia in patients with DDH were determined by comparison with normal hips, and improvement in femoral-head coverage was analysed again after virtual PAO. A customised surgery programme for each DDH patient was designed and provided the reference for the actual operation.

Results

We produced a 3D pelvic model using image processing software, doing precise measurement and with close approximation to the actual PAO. Lateral centre-edge angle (LCEA), anterior centre-edge angle (ACEA), acetabular anteversion angle (AAVA), anterior acetabular sector angle (AASA) and posterior acetabular sector angle (PASA) of normal hips in the control group were 35.128?±?6.337, 57.052?±?6.853, 19.215?±?5.504, 61.537?±?7.291 and 99.434?±?8.372°, respectively. Angles of hips with DDH before surgery were 11.46?±?11.19, 35.79?±?13.75, 22.77?±?6.13, 43.58?±?9.15 and 88.46?±?8.24, which were corrected to 33.81?±?2.36, 55.38?±?2.09, 20.16?±?2.18, 58.29?±?7.60, and 4.71?±?7.75°, respectively, after surgery. After virtual Bernese PAO, LCEA, ACEA, AAVA, AASA and PASA were corrected significantly (p?<?0.01). There was no statistically significant differences between LCEA, ACEA and AAVA after virtual Bernese PAO and normal hips (p?=?0.06, p?=?0.23, p?=?0.06°, respectively). AASA improved significantly (p?=?0.002) post-operatively at the cost of reducing posterior coverage represented by PASA, which is significantly smaller than in normal and pre-operative hips of DDH patients (p?<?0.01).

Conclusions

The geometric feature of the pelvis for patients with DDH can be assessed comprehensively by using 3D-CT reconstruction and image processing technology. Based on this method, surgeons can design individualised treatment scheme and improve the effect of PAO.

     

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。     

The Influence of Pelvic Tilt on the Anteversion Angle of the Acetabular Prosthesis

The concept of the “safe area” of the acetabular prosthesis has a long history and has been recognized by many scholars. It is generally believed that postoperative hip dislocation rate is low, when the acetabular anteversion angle is placed in the range of 15° ± 10°. Despite this, hip dislocation is a common complication after total hip arthroplasty. In recent years, more and more scholars have paid attention to the influence of pelvic tilt on the acetabular anteversion angle. The concept of acetabular anteversion changes as the pelvic tilt changes, and is challenging the traditional acetabular prosthesis “safe area.” This study summarized the potential influencing factors of pelvic tilt and discussed the influence of the phenomenon on the anteversion angle of total hip arthroplasty (THA) acetabular prosthesis based on the literature review. We conclude that from the supine position to standing, followed by sitting, the pelvis tends to move backward. Pelvic sagittal activity, lumbar disease (ankylosing spondylitis), lumbar fusion (lumbar fusion, spine‐pelvic fusion), and other factors related to the tilt are THA risk factors for postoperative dislocation and revision. With the change of body position, the degree of acetabular anteversion is directly related to the degree of pelvic tilt. The acetabular anteversion varies greatly, which leads to increased hip prosthesis wear and even hip dislocation. The lateral X‐ray of the spine and pelvis is recommended in supine, standing, and sitting positions before THA. In addition, the pelvic tilt should be regarded as a reference of the acetabular prosthesis in the preoperative planning of THA.     

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<0.001）。。结论：伴有腰椎退变性后凸畸形的人工髋关节置换,根据术前对患者的评估分类,可以借助骨盆前平面参考支架,获得更佳的髋臼假体功能性前倾角。     

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。     

骨盆旋转对全髋关节置换术中髋臼假体安放角度的影响

目的：研究骨盆沿人体三维方向旋转对全髋关节置换术中髋臼假体实际安放角度的影响规律。方法：采集正常成人的骨盆CT影像学资料,采用电脑软件三维重建骨盆髋臼并模拟骨盆分别围绕与人体矢状面、横断面和冠状面垂直的X轴、Y轴和Z轴旋转时,以标准角度植入髋臼假体时测量臼杯的放射外展角（radiographic inclination,RI）和放射前倾角（radiographic anteversion,RA）。采用相关性分析量化各个轴向旋转角度与髋臼实际角度的关系。结果：骨盆沿X轴及Y轴旋转时对髋臼的RA影响较小,但对RI影响较大并呈线性相关,回归方程分别为RA=0.682 4X+10.256（r²=0.308 4）和RA=-0.714 1Y+10.424（r²=0.999 8）;骨盆沿Z轴旋转时对RA几乎无影响,但与RI呈线性相关,回归方程为RI=1.0Z+46（r²=1.0）。结论：骨盆的前后旋转或沿躯体的纵轴旋转均明显影响髋臼的前倾角,但对外展角影响较小;相反,骨盆在冠状面上的左右歪斜可明显影响髋臼的外展角,但不影响其前倾角。     

Error in acetabular socket alignment due to the thick anterior pelvic soft tissues

The aim of this study was to assess how much the digitizing error attributable to the thick soft tissues in the anterior pelvic area can affect the targeted acetabular socket alignment. The acetabular socket orientation angle was measured by using a synthetic pelvic model and an OrthoPilot total hip arthroplasty (Aesculap AG & Co KG, Tuttlingen, Germany) navigation system. The anterior pelvic plane was defined using 3 bony landmarks: the ipsilateral and contralateral anterior superior iliac spines (ASIS) and the center of the 2 pubic tubercles. The digitization error of 1 cm at the ipsilateral ASIS, contralateral ASIS, and the center of the two pubic tubercles resulted in 1.8°, 4.4°, and −6.8° in anteversion, and 1.4°, 0.2°, and −0.2° in abduction, respectively. The current navigation system based on the anterior pelvic plane may produce considerable error in guiding the acetabular socket anteversion for patients with thick soft tissue in the anterior pelvic area.     

髂臼成形骨盆截骨术治疗幼儿发育性髋脱位的疗效

目的探讨髂臼成形(Pemberton)骨盆截骨术治疗幼儿发育性髋脱位(DDH)的疗效。方法对54例DDH患儿采用Pemberton骨盆截骨术治疗。记录临床随访结果和髋关节解剖结构参数。末次随访时,采用Mckay评估标准评价髋关节功能,采用Severin标准评价髋关节形态和复位情况。结果单侧DDH患儿均获得9个月随访;双侧DDH患儿先手术侧获15~18个月随访,后手术侧获9个月随访。术后3个月,患儿股骨、髋臼截骨处均愈合,无重要血管神经损伤、截骨处明显感染等并发症发生。术后6个月、末次随访时髋关节各解剖结构参数均较术前改善明显(P<0.05);与术后6个月相比,末次随访时,骨性髋臼指数(AI)和髋臼深度逐渐增大(P<0.05),中心边缘角(CE角)、髋臼顶宽度和Reimers不稳定指数逐渐减小(P<0.05),髋关节各解剖结构参数已逐步接近同龄正常儿童。末次随访时,单侧DDH患儿患侧的髋臼顶宽度、臼头指数均明显高于健侧(P<0.05),AI、CE角、髋臼深度患侧与健侧比较差异均无统计学意义(P>0.05)。末次随访时,4例髋臼Y形软骨已闭合,其中1例Y形软骨早闭;采用Mckay评估标准评价髋关节功能的优良率为86.67%;采用Severin标准评价髋关节形态和复位情况的优良率为83.33%。结论Pemberton骨盆截骨术可以有效纠正DDH,修复髋关节功能,促进骨骺生长及患儿康复,效果显著。     

Axial plane coverage and torsion measurements in primary osteoarthritis of the hip with good frontal plane coverage and spherical femoral head

Introduction

Mechanical factors play a role in pathogenesis of primary osteoarthritis of the hip. Torsion measures were made to detect whether there is a causal relationship between increase or decrease of femoral anteversion, acetabular anteversion, and osteoarthritis. There are no studies in the literature indicating a relationship between axial plane coverage and osteoarthritis of the hip. Deficient axial plane coverage of femoral head may also play a role in pathogenesis of osteoarthritis.

Materials and methods

Thirty patients with primary osteoarthritis of the hip and 29 control cases were included in the study. We used the method of Anda et al. (Acta Radiol Diagn 27:443–447, 1986; Comput Assist Tomogr 15:115–120, 1991) to measure axial plane anterior, posterior coverages in patients with primary osteoarthritis of the hip. The computerized tomography sections and pelvic radiographs indicated good frontal plane coverage and spherical femoral head. In addition to anterior acetabular sector angle, posterior acetabular sector angle, horizontal acetabular sector angles for axial plane coverage detection, femoral anteversion, acetabular anteversion, and McKibbin instability index were also measured.

Results

Posterior coverage was lower at osteoarthritic hips than the control group’s hips (96.0 ± 16.7, 104.2 ± 10.6) (p < 0.05).

Conclusion

The results may indicate that in addition to other mechanical factors, axial plane coverage, especially the posterior coverage deficiency, may play a role in the pathogenesis of hip osteoarthritis.     

Sex differences in reference values of hip acetabular measurements using computed tomography in Japanese adults and the effect of aging on the measurement parameters

BackgroundIt is very important to understand the acetabular morphology of the normal hip joint to assist in diagnosis and surgical planning of hip disorders. The purpose of the present study was to obtain gender-based reference values for the acetabular measurements of a normal hip using computed tomography data and investigate the effect of aging on the measurement values.MethodsWe measured acetabular parameters (center-edge angle, Sharp angle, vertical center anterior angle, acetabular anteversion) on computed tomography corrected for changing the obliquity, rotation, and tilt of the pelvis. We performed measurements in 245 patients (490 joints; 120 men [240 joints] and 125 women [250 joints]). The mean age was 64.7 ± 14.3 (31–88) years for men and 63.2 ± 15.2 (30–88) years for women.ResultsIn men and women, the mean center-edge angle was 31.8° ± 6.4° and 30.6° ± 6.5°, the mean Sharp angle was 38.6° ± 3.2° and 40.6° ± 3.8°, the mean vertical center anterior angle was 44.3° ± 7.9° and 40.0° ± 8.5°, and the mean acetabular anteversion angle was 14.3° ± 5.2° and 18.8° ± 5.4°, respectively. All differences were statistically significant. The center-edge angle increased with age in women; however, such an effect was not observed in men. The other measurements showed a similar trend, such as larger vertical center anterior angle and smaller Sharp and acetabular anteversion angles, with aging in both men and women.ConclusionsWe used computed tomography data to quantitatively assess the coverage and shape of the acetabulum in adult Japanese subjects and obtain the estimated reference ranges by gender. The results also proved that the measurements changed with aging in both sexes. These facts must be taken into account during the diagnosis of hip disease and planning of surgery.     

成人髋关节发育不良不同Crowe分型的三维CT影像学特征

 目的 通过三维CT重建分析成人髋关节发育不良不同Crowe分型之间髋臼形态的演变规律。方法 2010年6月至2013年1月收治成人髋关节发育不良患者62例68髋,男6例8髋,女56例60髋;年龄47~59岁,平均（53.7±5.8）岁。CroweⅠ型14例17髋,Ⅱ型17例17髋,Ⅲ型15例17髋,Ⅳ型16例17髋。行标准髋关节CT扫描及三维重建。在侧位三维图像上标记Harris窝,确定髋臼旋转中心,利用十字坐标轴确定髋臼旋转中心的冠状面和横断面位置;在正位三维图像上利用Ranwant三角确定髋臼旋转中心的矢状面位置;在髋臼水平重建图像上确定髋臼旋转中心。观察髋臼前后缘增生及髋臼前后柱发育不良程度,测量并比较不同Crowe分型患者的髋臼前倾角、前覆盖角、后覆盖角和内壁宽度。结果 随Crowe分型增加,髋臼前倾角逐渐加大,两者呈正相关,除CroweⅠ型和Ⅱ型组间外,其余组间差异有统计学意义;髋臼前覆盖角逐渐减小,两者呈负相关,各组间差异均有统计学意义,CroweⅢ、Ⅳ型组平均值小于50°;髋臼后覆盖角逐渐减小,两者呈负相关,各组间差异均有统计学意义, CroweⅢ、Ⅳ型组平均值小于90° ;髋臼内壁宽度逐渐增加,两者呈正相关,各组间差异均有统计学意义。结论 不同Crowe分型成人髋关节发育不良的髋臼形态变化存在一定的演变规律。对CroweⅠ型和Ⅱ型髋臼的重建可充分利用髋臼前后柱骨量,对CroweⅢ、Ⅳ型髋臼的重建可适度上移和（或）内移髋臼中心。     

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。     

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.     

How Do Acetabular Version and Femoral Head Coverage Change With Skeletal Maturity?

BackgroundNormal changes in acetabular version over the course of skeletal development have not been well characterized. Knowledge of normal version development is important because acetabular retroversion has been implicated in several pathologic hip processes.Questions/purposesThe purpose of this study was to characterize the orientation of the acetabulum by measuring (1) acetabular version and (2) acetabular sector angles in pediatric patients during development. We also sought to determine whether these parameters vary by sex in the developing child.MethodsWe evaluated CT images of 200 hips in 100 asymptomatic pediatric patients (45 boys, 55 girls; mean age, 13.5 years; range, 9–18 years) stratified by the status of the triradiate physis and sex. We determined the acetabular anteversion angle at various levels in the axial plane as well as acetabular sector angles at five radial planes around the acetabulum.ResultsFor both genders, anteversion angle was greater for the closed physis group throughout all levels (p < 0.001) and both open and closed physis groups were more anteverted as the cut moved caudally away from the acetabular roof (p < 0.001). At the center of the femoral head, the mean anteversion angle (± SD) in girls was 15° ± 3° in the open group and 19° ± 5° in the closed group (p < 0.001). In boys, the mean anteversion angle increased from 14° ± 4° in the open group to 19° ± 4° in the closed group (p = 0.003). In the superior, posterosuperior, and posterior planes, the acetabular sector angles were greater in the closed compared with the open physis group for both boys and girls with the largest increase occurring in the male posterosuperior plane (approximately 20°) (all p < 0.05).ConclusionsThis study demonstrates that acetabular anteversion and acetabular sector angles in both male and female subjects increase with skeletal maturity as a result of growth of the posterior wall. This suggests that radiographic appearance of acetabular retroversion may not be attributable to overgrowth of the anterior wall but rather insufficient growth of the posterior wall, which has clinical treatment implications for pincer-type impingement.

Level of Evidence

Level IV diagnostic study.     

应用双髋关节正位X线片评估全髋关节置换术后髋臼前倾角

目的: 探讨是否可以在普通双髋关节正位X线片上评估髋臼假体前倾角。方法: 2019年3月至7月收治全髋关节置换术后患者32例(共41髋),男18例,女14例,年龄(66.2±4.1)岁,所有患者于术后完成双髋关节正位X线片及骨盆CT平扫。通过骨盆CT平扫测量髋臼前倾角,在X线片上采用Saka等测量公式进行测量。结果: 41髋X线片测量髋臼前倾角为(16.2±5.0)°,与CT测量的髋臼前倾角(31.8±9.7)°间差异有统计学意义(P=0.00)。此外,X线片测量与CT测量的髋臼前倾角具有明显相关性(Pearson相关系数r=0.84,P=0.00)。结论: CT可以较准确地测得髋臼前倾角,但是其存在辐射量大、成本较高、假体CT伪影重等明显弊端。在普通双髋关节正位X线片上采用Saka测量公式虽然无法像CT测量一样直接获得准确的髋臼前倾角,但却和CT测得的髋臼前倾角间存在高度的相关性,所以提出的方法也可以初步评估髋臼前倾角。     

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.     

Is Combined Anteversion Equally Affected by Acetabular Cup and Femoral Stem Anteversion?

BackgroundTo create a safe zone, an understanding of the combined femoral and acetabular mating during hip motion is required. We investigated the position of the femoral head inside the acetabular liner during simulated hip motion. We hypothesized that cup and stem anteversions do not equally affect hip motion and combined hip anteversion.MethodsHip implant motion was simulated in standing, sitting, sit-to-stand, bending forward, squatting, and pivoting positions using the MATLAB software. A line passing through the center of the stem neck and the center of the prosthetic head exits at the polar axis (PA) of the prosthetic head. When the prosthetic head and liner are parallel, the PA faces the center of the liner (PA position = 0, 0). By simulating hip motion in 1-degree increments, the maximum distance of the PA from the liner center and the direction of its movement were measured (polar coordination system).ResultsThe effect of modifying cup and stem anteversion on the direction and distance of the PA’s change inside the acetabular liner was different. Stem anteversion influenced the PA position inside the liner more than cup anteversion during sitting, sit-to-stand, squatting, and bending forward (P = .0001). This effect was evident even when comparing stems with different neck angles (P = .0001).ConclusionCup anteversion, stem anteversion, and stem neck-shaft angle affected the PA position inside the liner and combined anteversion in different ways. Thus, focusing on cup orientation alone when assessing hip motion during different daily activities is inadequate.     

Cranial acetabular retroversion is common in developmental dysplasia of the hip as assessed by the weight bearing position

Background and purpose The appearance of acetabular version differs between the supine and weight bearing positions in developmental dysplasia of the hip. Weight bearing radiographic evaluation has been recommended to ensure the best coherence between symptoms, functional appearance, and hip deformities. Previous prevalence estimates of acetabular retroversion in dysplastic hips have been established in radiographs recorded with the patient supine and with inclusion only if pelvic tilt met standardized criteria. We assessed the prevalence and the extent of acetabular retroversion in dysplastic hip joints in weight bearing pelvic radiographs.

Patients and methods We assessed 95 dysplastic hip joints (54 patients) in weight bearing anteroposterior pelvic radiographs, measuring the acetabular height and the distance from the acetabular roof to the point of crossing of the acetabular rims, if present.

Results Acetabular retroversion was found in 31 of 95 dysplastic hip joints. In 28 of 31 hip joints with retroversion, crossover of the acetabular rims was positioned within the cranial 30% sector. The degree of pelvic tilt differed between retroverted and non-retroverted dysplastic hip joints, though only reaching a statistically significant level in male dysplastic hip joints.

Interpretation We identified cranial acetabular retroversion in one-third of dysplastic hip joints when assessed on weight bearing pelvic radiographs. If assessed on pelvic radiographs obtained with the patient supine, and with inclusion only if the degree of pelvic tilt meets standardized criteria, the prevalence of acetabular retroversion may be underestimated.