Department of Orthopedic Surgery, Regensburg University Medical Center, Asklepios Klinikum Bad Abbach, Kaiser-Karl V.-Allee 3, 93077, Bad Abbach, Germany,
Clin Orthop Relat Res. 2014 Oct;472(10):3150-8. doi: 10.1007/s11999-014-3740-5. Epub 2014 Jun 26.
Restoration of biomechanics is a major goal in THA. Imageless navigation enables intraoperative control of leg length equalization and offset reconstruction. However, the effect of navigation compared with intraoperative fluoroscopy is unclear.
QUESTIONS/PURPOSES: We asked whether intraoperative use of imageless navigation (1) improves the relative accuracy of leg length and global and femoral offset restoration; (2) increases the absolute precision of leg length and global and femoral offset equalization; and (3) reduces outliers in a reconstruction zone of ± 5 mm for leg length and global and femoral offset restoration compared with intraoperative fluoroscopy during minimally invasive (MIS) THA with the patient in a lateral decubitus position.
In this prospective study a consecutive series of 125 patients were randomized to either navigation-guided or fluoroscopy-controlled THA using sealed, opaque envelopes. All patients received the same cementless prosthetic components through an anterolateral MIS approach while they were in a lateral decubitus position. Leg length, global or total offset (representing the combination of femoral and acetabular offset), and femoral offset differences were restored using either navigation or fluoroscopy. Postoperatively, residual leg length and global and femoral offset discrepancies were analyzed on magnification-corrected radiographs of the pelvis by an independent and blinded examiner using digital planning software. Accuracy was defined as the relative postoperative difference between the surgically treated and the unaffected contralateral side for leg length and offset, respectively; precision was defined as the absolute postoperative deviation of leg length and global and femoral offset regardless of lengthening or shortening of leg length and offset throughout the THA. All analyses were performed per intention-to-treat.
Analyzing the relative accuracy of leg length restoration we found a mean difference of 0.2 mm (95% CI, -1.0 to +1.4 mm; p = 0.729) between fluoroscopy and navigation, 0.2 mm (95 % CI, -0.9 to +1.3 mm; p = 0.740) for global offset and 1.7 mm (95 % CI, +0.4 to +2.9 mm; p = 0.008) for femoral offset. For the absolute precision of leg length and global and femoral offset equalization, there was a mean difference of 1.7 ± 0.3 mm (p < 0.001) between fluoroscopy and navigation. The biomechanical reconstruction with a residual leg length and global and femoral offset discrepancy less than 5 mm and less than 8 mm, respectively, succeeded in 93% and 98%, respectively, in the navigation group and in 54% and 95%, respectively, in the fluoroscopy group.
Intraoperative fluoroscopy and imageless navigation seem equivalent in accuracy and precision to reconstruct leg length and global and femoral offset during MIS THA with the patient in the lateral decubitus position.
恢复生物力学是全髋关节置换术（THA）的主要目标。无图像导航可实现术中下肢长度均衡和偏心距重建的控制。然而，导航与术中透视的效果尚不清楚。
问题/目的：我们想知道术中使用无图像导航（1）是否能提高下肢长度和整体及股骨偏心距恢复的相对准确性；（2）是否能提高下肢长度和整体及股骨偏心距均衡的绝对精度；（3）与术中透视相比，在微创（MIS）THA 中患者处于侧卧位时，是否能减少重建区（± 5mm）下肢长度和整体及股骨偏心距恢复的离群值。
在这项前瞻性研究中，连续 125 例患者被随机分为导航引导或透视控制 THA，使用密封的不透明信封。所有患者均通过前外侧 MIS 入路接受相同的非骨水泥假体组件，同时患者处于侧卧位。使用导航或透视来恢复下肢长度、整体或总偏心距（代表股骨和髋臼偏心距的组合）和股骨偏心距差异。术后，由独立的、盲法的检查者使用数字规划软件，在骨盆的放大校正 X 光片上分析术后残留的下肢长度和整体及股骨偏心距差异。准确性定义为手术治疗侧与未受影响的对侧之间的术后相对差异，分别为下肢长度和偏心距；精度定义为下肢长度和整体及股骨偏心距的术后绝对偏差，无论整个 THA 过程中下肢长度和偏心距的延长或缩短。所有分析均采用意向治疗。
分析下肢长度恢复的相对准确性，我们发现透视与导航之间的平均差异为 0.2mm（95%CI，-1.0 至 +1.4mm；p=0.729），整体偏心距的平均差异为 0.2mm（95%CI，-0.9 至 +1.3mm；p=0.740），股骨偏心距的平均差异为 1.7mm（95%CI，+0.4 至 +2.9mm；p=0.008）。对于下肢长度和整体及股骨偏心距均衡的绝对精度，透视与导航之间的平均差异为 1.7±0.3mm（p<0.001）。在导航组中，有 93%的患者下肢长度和整体及股骨偏心距差值分别小于 5mm 和 8mm，有 98%的患者股骨偏心距差值小于 5mm，在透视组中，有 54%的患者下肢长度和整体及股骨偏心距差值分别小于 5mm 和 8mm，有 95%的患者股骨偏心距差值小于 5mm。
在患者处于侧卧位的微创 THA 中，术中透视和无图像导航在下肢长度和整体及股骨偏心距的准确性和精度方面似乎相似。
