Abstract
目的
探讨发育性髋关节发育不良（developmental dysplasia of the hip，DDH）和正常髋关节的髋臼旋转角（acetabular tilt angle，ATA）是否存在差异，以及 DDH 中 ATA 对髋臼角度的影响。
方法
以 2009 年 2 月—2015 年 10 月收治并符合选择标准的 31 例（39 髋）女性 DDH 患者作为 DDH 组，患者年龄 18～59 岁，平均 39 岁；另选择 31 例（31 髋）无髋关节疾患的膝关节骨性关节炎拟行人工膝关节置换术的女性患者作为对照组，患者年龄 52～79 岁，平均 69 岁。两组均行骨盆 CT 扫描及三维重建，测量 ATA、髋臼前倾角（acetabular anteversion angle，AAA）、髋臼外展角（acetabular inclination angle，AIA）、髋臼近端前倾角（acetabular cranial anteversion angle，ACAA）及髋臼扇形角（acetabular sector angle，ASA）；其中以 ASA 评估髋臼对股骨头的覆盖。采用 Pearson 相关分析 ATA 与 AAA、AIA、ACAA 的相关性，以及 ATA、AAA 及 AIA 与各方向 ASA 的相关性。
结果
DDH 组 ATA、AAA、AIA 均大于对照组，前侧、上侧、后侧 ASA 均小于对照组，比较差异有统计学意义（P<0.05）；两组 ACAA 差异无统计学意义（t=1.918，P=0.523）。DDH 组 ATA 与 AAA 和 ACAA 成正相关（r=0.439，P=0.001；r=0.436，P=0.002），与 AIA 无相关性（r=0.123，P=0.308）；对照组 ATA 与 AAA、ACAA、AIA 均无相关性（r=–0.004，P=0.724；r=–0.079，P=0.626；r=–0.058，P=0.724）。髋臼覆盖方面，DDH 组中，ATA、AAA 与前侧 ASA 成负相关（P<0.05），与后侧 ASA 成正相关（P<0.05），与上侧 ASA 无相关性（P>0.05）；AIA 与前侧、上侧 ASA 成负相关（P<0.05），与后侧 ASA 无相关性（r=–0.092，P=0.440）。对照组中，ATA 与各方向 ASA 均无相关性（P>0.05）。DDH 前壁缺损 18 髋（46.2%）、侧方缺损 15 髋（38.5%）、后壁缺损 6 髋（15.3%）。前壁、侧方、后壁缺损的 ATA 分别为（22.91±5.06）、（21.59±3.81）、（15.70±10.00）°，后壁缺损的 ATA 明显小于前壁及侧方缺损（P<0.05），前壁及侧方缺损的 ATA，比较差异无统计学意义（P>0.05）。
结论
DDH 的 ATA 影响髋臼角度，因此对于髋臼前外侧缺损的 DDH 行髋臼旋前截骨术合理，对于髋臼后壁缺损的 DDH 则应避免行髋臼旋前截骨术。
Keywords: 髋关节发育不良, 髋臼旋转角, 髋臼角度, 髋臼周围截骨
Abstract
Objective
To investigate the difference in acetabular tilt angle (ATA) between adults with deve-lopmental dysplasia of the hip (DDH) and normal adults and the effect of ATA on acetabular version.
Methods
Between February 2009 and October 2015, 31 adult female patients with DDH (39 hips) (DDH group) and 31 female patients with osteoarthritis of the knee (31 hips) who had no history of hip disease (control group) were included in this study. The average age was 39 years (range, 18-59 years) in the DDH group, and was 69 years (range, 52-79 years) in control group. The morphometric parameters of the acetabulum including ATA, acetabular anteversion angle (AAA), acetabular inclination angle (AIA), acetabular cranial anteversion angle (ACAA), and acetabular sector angle (ASA) were mea- sured by CT reconstruction; The ASA was used as an index for acetabular coverage of the femoral head. The correlation between ATA and other parameters was analyzed using Pearson correlation analysis.
Results
The values of ATA, AAA, and AIA of the DDH group were significantly larger than those of the control group (P<0.05). The ASA in all directions was significantly decreased in the DDH group when compared with the values in the control group (P<0.05). There was no significant difference in ACAA between two groups (t=1.918, P=0.523). The ATA was positively correlated with AAA and ACAA in the DDH group (r=0.439, P=0.001; r=0.436, P=0.002), but there was no correlation between ATA and AIA (r=0.123, P=0.308). In the control group, the ATA was not correlated with AAA, ACAA, and AIA (r=–0.004, P=0.724; r=–0.079, P=0.626; r=–0.058, P=0.724). Regarding acetabular coverage of the femoral head, the ATA and AAA were correlated negatively with anterior ASA (P<0.05) and positively with posterior ASA (P<0.05), but had no correlation with superior ASA (P>0.05) in the DDH group; AIA was correlated negatively with anterior ASA and superior ASA (P<0.05) and had no correlation with posterior ASA (r=–0.092, P=0.440). In the control group, there was no correlation between ATA and ASA in any direction (P>0.05). In the DDH group, defects of the acetabular anterior wall, lateral wall, and posterior wall were observed in 18 hips (46.2%), 15 hips (38.5%), and 6 hips (15.3%), respectively. ATA value of the posterior wall defect [(15.70±10.00)°] was significantly smaller than those of the acetabular anterior wall and lateral wall defects [(22.91±5.06)° and (21.59±3.81) °] (P<0.05), but no signficant difference was found between anterior wall and lateral wall defects (P>0.05).
Conclusion
ATA will influence acetabular version in DDH. The anterior rotation of the acetabular fragment during periacetabular osteotomies is an anatomically reasonable maneuver for hips with anterolateral acetabular defect, while the maneuver should be avoided in hips with posterior acetabular defect.
Keywords: Developmental dysplasia of the hip, acetabular tilt angle, acetabular version, periacetabular osteotomies
发育性髋关节发育不良（developmental dyspla-sia of the hip，DDH）是继发性髋关节骨性关节炎的常见病因[1]。DDH 髋关节形态结构异常，包括髋臼对股骨头覆盖不足、髋臼较浅、股骨过度前倾、股骨颈短缩、髋外翻等[2-5]。这些异常形态会导致关节承重面减少，关节软骨压力异常分布，关节接触面压力升高[6-7]。因此，与正常髋关节人群相比，DDH 患者常较早出现盂唇撕裂、关节软骨退变，最终导致过早出现骨性关节炎[8-11]。尽管大部分 DDH 患者表现为髋臼前外侧壁缺损，但 DDH 髋臼角度、髋臼质量、缺损部位个体差异较大[12-17]。因此，髋臼周围截骨术前准确评估患者髋臼形态，根据形态特征制定矫形方案具有重要临床意义[18-21]。有研究表明，如异常髋臼角度和覆盖矫形不理想，会严重影响治疗效果[22-24]。
目前对 DDH 髋臼相对骨盆的旋转角度和病理特征研究较少，Köhnlein 等[25]研究发现，正常髋关节的髋臼旋转角（acetabular tilt angle，ATA）变化较大。由于髋臼缘不对称，呈波浪状，有 3 个突起和 3 个凹陷[25-28]，所以 ATA 的变化可能对髋臼角度以及髋臼对股骨头的覆盖产生影响。明确 ATA 与髋臼角度及髋臼对股骨头的覆盖的相关性，对髋臼周围截骨等髋臼矫形手术具有指导意义。鉴于此，本研究通过测量 DDH 患者和髋关节结构正常者 ATA 和髋臼角度，比较研究两者 ATA 差异、ATA 与髋臼角度的相关性，进一步明确 ATA 用于指导髋臼周围截骨术的意义。报告如下。
1. 资料与方法
1.1. 研究对象
DDH 患者纳入标准：① 年龄>18 岁的女性 DDH 患者，因 DDH 患者多为女性，为消除性别引起的髋臼形态差异，故只纳入女性患者；② 髋关节仅有轻微或无骨性关节炎表现；③ 骨盆前后位 X 线片显示外侧中心-边缘角<20°。排除标准：① 合并退变性髋关节炎及股骨头缺血性坏死型髋关节炎；② 曾行髋关节截骨矫形术者；③ 参照 Tönnis 骨性关节炎分型标准[29]达 2 度及以上者。2009 年 2 月—2015 年 10 月，共 31 例（39 髋）患者符合选择标准纳入 DDH 组。患者年龄 18～59 岁，平均 39 岁。
另选择 31 例因膝关节骨性关节炎拟行人工膝关节置换术的女性患者作为对照组，经髋关节 X 线片和 CT 明确患者髋关节无退变、无形态学异常（共 31 髋）。患者年龄 52～79 岁，平均 69 岁；外侧中心-边缘角 25～42°，平均 37°。经患者知情同意后行骨盆 CT 扫描及三维重建。
1.2. 测量方法
两组患者平卧于 CT 检查床，取双下肢旋转中立位，扫描范围：自骨盆上缘至骨盆下缘。采用 256 层 Philips Brilliance iCT 仪（Philips 公司，德国），扫描条件：电压 120 kV、电流 100 mA、层厚 3 mm、间距 0.9 mm。以 Dicom 格式下载扫描影像学资料，于 Mimics16.0 软件中行三维重建，并测量以下指标：① ATA[30]：ATA 定义为矢状位上整个髋臼相对骨盆前平面的旋转角度；测量方法为髋臼中心和髋臼足印区下缘中点的连线与骨盆前平面的夹角，ATA 增加提示髋臼后旋增加。② 髋臼前倾角（acetabular anteversion angle，AAA）：测量方法为通过股骨头中心的横断面上的髋臼前后缘连线与矢状线的夹角。③ 髋臼外展角（acetabular inclination angle，AIA）：测量方法为通过股骨头中心的冠状面上髋臼上、下缘连线与水平线的夹角。④ 髋臼近端前倾角（acetabular cranial anteversion angle，ACAA）[31]：测量方法为距离臼顶远端 5 mm 的髋臼前后缘连线和矢状线的夹角，ACAA 为负数提示髋臼后倾。⑤ 髋臼扇形角（acetabular sector angle，ASA）[32]：以 ASA 评估髋臼对股骨头的覆盖，测量方法为股骨头中心和髋臼边缘连线与水平线的夹角，ASA 值越小，表明髋臼对股骨头的覆盖越少；测量髋臼前侧 ASA（anterior ASA，AASA）、上侧 ASA（superior ASA，SASA）和后侧 ASA（posterior ASA，PASA）。按 AASA 和 PASA 将 DDH 组患者分为 3 个亚组[15, 33]：分别为前壁缺损（AASA<50°、PASA≥90°）、后壁缺损（AASA≥50°、PASA<90°）、侧方缺损（AASA<50°、PASA<90°或 AASA≥50°、PASA≥90°）。见图 1。
图 1.
Schematic diagram of acetabulum parameters measurement
影像学指标测量示意图
a. ATA; b. AIA; c. AAA; d. ACAA; e. ASA
a. ATA; b. AIA; c. AAA; d. ACAA; e. ASA
1.3. 统计学方法
采用 SPSS19.0 统计软件进行分析。数据以均数±标准差表示，组间比较采用 t 检验；采用 Pearson 相关分析进行两组内 ATA 与 AAA、ACAA 及 AIA 相关性，以及各方向 ASA 与 ATA、AAA 及 AIA 的相关性检验；DDH 组中前壁缺损、侧方缺损、后壁缺损 3 个亚组间 ATA 比较采用方差分析，两两比较采用 SNK 检验；检验水准取双侧 α=0.05。
2. 结果
DDH 组 ATA、AAA、AIA 均显著大于对照组，AASA、SASA 和 PASA 均显著小于对照组，比较差异均有统计学意义（P<0.05）；两组 ACAA 比较差异无统计学意义（t=1.918，P=0.523）。见表 1。
表 1.
Comparison of acetabulum parameters between the DDH and control groups (°,
)
两组各髋臼角度比较（°，
）
| 组别
Group |
例数
n |
ATA | AAA | AIA | ACAA | AASA | SASA | PASA |
| DDH 组
DDH group |
39 | 23.39±11.02 | 22.42±7.19 | 49.33±5.89 | 3.93±12.85 | 47.00±14.08 | 94.33±13.86 | 85.60±12.16 |
| 对照组
Control group |
31 | 20.12± 8.10 | 18.82±7.08 | 42.27±5.27 | 4.52± 8.72 | 56.90± 6.86 | 122.16± 8.77 | 90.88± 8.37 |
| 统计值
Statistic |
t=3.346
P=0.017 |
t=2.567
P=0.000 |
t=4.815
P=0.000 |
t=1.918
P=0.523 |
t=2.444
P=0.014 |
t=–5.582
P= 0.041 |
t=2.532
P=0.028 |
DDH 组 ATA 与 AAA 和 ACAA 成正相关（r=0.439，P=0.001；r=0.436，P=0.002），与 AIA 无相关性（r=0.123，P=0.308）；对照组 ATA 与 AAA、ACAA、AIA 均无相关性（r=–0.004，P=0.724；r=–0.079，P=0.626；r=–0.058，P=0.724）。
髋臼覆盖方面，DDH 组中，ATA、AAA 与 AASA 成负相关（P<0.05），与 PASA 成正相关（P<0.05），与 SASA 无相关性（P>0.05）；AIA 与 AASA、SASA 成负相关（P<0.05），与 PASA 无相关性（r=–0.092，P=0.440）。对照组中，ATA 与各方向 ASA 均无相关性（P>0.05）；AAA 与 AASA 成负相关、与 PASA 成正相关（P<0.05），而与 SASA 无相关性（r=–0.152，P=0.348）；AIA 与 AASA、PASA 均无相关性（P>0.05），而与 SASA 成负相关（r=–0.703，P=0.000）。见表 2、3。
表 2.
Correlation of ASA with ATA, AAA, and AIA in the DDH group
DDH 组中各方向 ASA 与 ATA、AAA、AIA 的相关性分析
| 参数
Parameter |
ATA | AAA | AIA |
| AASA | r=–0.439，P=0.000 | r=–0.752，P=0.001 | r=–0.368，P=0.002 |
| SASA | r=–0.172，P=0.151 | r=–0.204，P=0.085 | r=–0.758，P=0.000 |
| PASA | r= 0.373，P=0.001 | r= 0.679，P=0.000 | r=–0.092，P=0.440 |
表 3.
Correlation of ASA with ATA, AAA, and AIA in the control group
对照组中各方向 ASA 与 ATA、AAA、AIA 的相关性分析
| 参数
Parameter |
ATA | AAA | AIA |
| AASA | r=–0.004，P=0.791 | r=–0.606，P=0.000 | r= 0.303，P=0.058 |
| SASA | r= 0.006，P=0.971 | r=–0.152，P=0.348 | r=–0.703，P=0.000 |
| PASA | r= 0.021，P=0.896 | r= 0.637，P=0.000 | r=–0.083，P=0.611 |
DDH 前壁缺损 18 髋（46.2%）、侧方缺损 15 髋（38.5%）、后壁缺损 6 髋（15.3%）。前壁、侧方、后壁缺损的 ATA 分别为（22.91±5.06）、（21.59±3.81）、（15.70±10.00）°，后壁缺损的 ATA 明显小于前壁及侧方缺损，差异有统计学意义（P<0.05）；前壁及侧方缺损之间的 ATA 比较，差异无统计学意义（P>0.05）。
3. 讨论
DDH 髋臼形态异常，且个体间差异较大，但目前对于 DDH 的 ATA 研究较少。本研究中，对照组 ATA 为（20.12±8.10）°，明显大于 Köhnlein 等[25]研究测量的（18.9°），我们认为该差异可能是测量方法不同引起的。Köhnlein 等研究是利用骨性骨盆标本测量，测量方法为以髋臼 12 点和 6 点方向的连线与骨盆前平面的夹角；而本研究测量是基于 CT 扫描图像，测量参考点也不同。此外，本研究发现 DDH 髋关节的 ATA 大于正常髋关节，提示髋臼后旋是 DDH 髋关节的特异形态之一。
目前，国内罕见关于 ATA 和髋臼角度及覆盖关系的研究报道。本研究通过测量分析 ATA 和髋臼角度、髋臼后倾、髋臼覆盖之间的关系，发现对照组正常髋关节 ATA 与髋臼角度、髋臼后倾、髋臼覆盖间无相关性，表明正常 ATA 对髋臼角度和髋臼对股骨头覆盖无影响；而 DDH 组 ATA 和 AAA 成正相关，与 AASA、PASA 相关，表明髋臼后旋会导致 AAA 增大，影响髋臼对股骨头的覆盖。DDH 组中前壁、侧方、后壁缺损的 ATA 分别为（22.91±5.06）、（21.59±3.81）、（15.70±10.00）°，后壁缺损的 ATA 显著小于前壁及侧方缺损，且差异有统计学意义。
髋臼周围截骨术时，根据 DDH 髋臼形态设计个体化矫形方案是关键。目前常规旋转截骨是前旋或前旋外展髋臼，纠正髋臼前外侧缺损，但有文献报道前旋髋臼会加剧髋臼后侧缺损[34-35]。本研究结果支持上述结论，理由如下：尽管 DDH 组 ATA 较大，但 3 个亚组中仅有前壁缺损及侧方缺损的 ATA 大于对照组正常髋关节 ATA，且 ATA 与 AASA 成负相关，通过髋臼旋前截骨，可减小 ATA 使之接近正常值，增加 AASA，纠正前壁、侧方缺损；而后壁缺损的 ATA 小于对照组正常髋关节 ATA，且 ATA 与 PASA 成正相关，如行髋臼旋前截骨，ATA 会进一步减小，更偏离正常值，后壁缺损加剧。因此对于后壁缺损的 DDH，应避免行髋臼旋前截骨。本研究 DDH 组中，前壁缺损 18 髋（46.2%）、侧方缺损 15 髋（38.5%）、后壁缺损 6 髋（15.3%），前壁、侧方缺损共占 84.7%，故对于大部分 DDH 可行旋前截骨，而对于后壁缺损患者不能进行旋前截骨。由于 ATA 测量方法较髋臼各部分缺损的测量方法更简单，临床中可通过测量 ATA 来判断缺损类型，指导矫形方案的设计。但本研究中后壁缺损仅 6 髋，其 ATA 测量值不能代表大样本后壁缺损数据，有待增加后壁缺损病例，统计并确定 ATA 范围，以此范围内避免行髋臼旋前截骨，使其具有更大的指导意义。
本研究还存在以下不足：① 样本量较少；② 对照组患者年龄大于 DDH 组，这与获取年轻志愿者骨盆 CT 难度较大有关，虽仅纳入影像学检查明确髋关节无疾患的患者，但结果分析仍存在一定偏倚。
Funding Statement
南通市卫生与计划生育委员会青年科研基金项目（WQZ2014002）
Natural Science Foundation for Youth of the Health and Family Planning Commission of Nantong City (WQZ2014002)
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