R. Zamora, University of Louisville, Louisville, KY, USA S. E. Punt, Department of Psychology, University of Kansas, Lawrence, KS, USA C. Christman-Skieller, J. C. Shapton, Department of Orthopaedics and Sports Medicine, University of Washington, Seattle, WA, USA C. Yildirim, Department of Orthopaedics, University of Health Sciences, Sultan Abdulhamid Han Training and Research Hospital, Uskudar, Istanbul, Turkey E. U. Conrad, Memorial Hermann Orthopedic and Spine Hospital, Bellaire, TX, USA.
Clin Orthop Relat Res. 2019 Dec;477(12):2692-2701. doi: 10.1097/CORR.0000000000000924.
To improve and achieve adequate bony surgical margins, surgeons may consider computer-aided navigation a promising intraoperative tool, currently applied to a relatively few number of patients in whom freehand resections might be challenging. Placing fiducials (markers) in the bone, identifying specific anatomical landmarks, and registering patients for navigated resections are time consuming. To reduce the time both preoperatively and intraoperatively, skin fiducials may offer an efficient and alternative method of navigation registration.
QUESTIONS/PURPOSES: (1) Does preoperative navigation using skin fiducials for registration allow the surgeon to achieve margins similar to those from bone fiducial registration in a simulated lower extremity tumor resection model in cadavers? (2) Does the use of preoperative navigation using skin fiducials for registration allow the surgeon to achieve similar bony margins in pelvic resections of simulated tumors as those achieved in long-bone resections using only skin fiducials for navigation in a cadaver model?
Simulated bone tumor resections were performed in three fresh-frozen cadavers with intact pelvic and lower-extremity anatomy using navigation guidance. We placed 5-cm intraosseous cement simulated bone tumors in the proximal/distal femur (n = 12), and proximal/distal tibia (n = 12) and pelvis (supraacetabular; n = 6). After bone tumor implantation, CT images of the pelvis and lower extremities were obtained. Each planned osseous resection margin was set at 10 mm. Navigation registration was performed for each simulated tumor using bone and skin markers that act as a point of reference (fiducials). The simulated bone tumor was resected based on a resection line that was established with navigation, and the corresponding osseous margins were calculated after resection. These margins were determined by an orthopaedic surgeon who was blinded to resection planning by the removal of cancellous bone around the cement simulated tumor. The shortest distance was measured from the cement to the resection line. Smaller mean differences between planned and postoperative margins were considered accurate. Independent t-tests were conducted to assess measurement differences between planned and postoperative margins at the 95% CI. Bland-Altman analyses were conducted to compare the deviation in margin difference between planned and postoperative margins in skin and bone fiducial registration, respectively.
In all, 84 total resection margins were measured with 48 long bone and 20 pelvic obtained with skin fiducials and 16 long bone obtained with bone fiducials. The planned mean margin was 10 mm for all long bone and pelvic resections. We found that skin fiducial and bone fiducial postoperative margins had comparable accuracy when resecting long bones (10 ± 2 mm versus 9 ± 2 mm, mean difference 1 [95% CI 0 to 2]; p = 0.16). Additionally, skin fiducial long bone postoperative margins were comparable in accuracy to pelvic supraacetabular postoperative margins obtained with skin fiducials (10 ± 2 mm versus 11 ± 3 mm, mean difference -1 mm [95% CI -3 to 1]; p = 0.22). When comparing the deviation in margin difference between planned and postoperative margins in skin and bone fiducial registration, 90% (61 of 68) of skin fiducial and 100% (16 of 16) bone fiducial postoperative margins fell within 2 SDs.
In this pilot study, skin fiducial markers were easy to identify on the skin surface of the cadaver model and on CT images used to plan margins. This technique appears to be an accurate way to plan margins in this model, but it needs to be tested thoroughly in patients to determine if it may be a better clinical approach than with bone fiducials.
The margins obtained using skin fiducials and bone fiducials for registration were similar and comparable in this pilot study with a very small effect size. Boundaries of the simulated tumors were not violated in any resections. Skin fiducials are easier to identify than bone fiducials (anatomic landmarks). If future clinical studies demonstrate that margins obtained using skin fiducials for registration are similar to margins obtained with anatomical landmarks, the use of navigation with skin fiducials instead of bone fiducials may be advantageous. This technique may decrease the surgeon's time used to plan for and localize registration points and offer an alternative registration technique, providing the surgeon with other registration approaches.
为了提高并确保获得充分的骨外科边缘，外科医生可能会考虑计算机辅助导航作为一种有前途的术中工具，目前仅将其应用于少数可能难以进行徒手切除的患者。在骨头上放置基准标记（标志物）、识别特定的解剖标志并为导航切除患者进行注册是很耗时的。为了减少术前和术中的时间，皮肤基准标记可能是一种有效的替代导航注册方法。
问题/目的：（1）在尸体模拟下肢肿瘤切除模型中，使用皮肤基准标记进行术前导航注册是否可以使外科医生获得与骨基准标记注册相似的边缘？（2）在尸体模型中，仅使用皮肤基准标记进行导航时，在骨盆切除模拟肿瘤中，使用术前导航注册使用皮肤基准标记是否可以使外科医生获得与使用长骨基准标记导航获得的相似的骨边缘？
使用导航引导在三个完整骨盆和下肢解剖的新鲜冷冻尸体上进行模拟骨肿瘤切除。我们在股骨近端/远端（n = 12）、胫骨近端/远端（n = 12）和骨盆（髋臼上）放置了 5 厘米的骨内水泥模拟肿瘤。骨肿瘤植入后，获取骨盆和下肢的 CT 图像。每个计划的骨切除边缘设置为 10 毫米。使用充当参考点的骨和皮肤标记（基准标记）对每个模拟肿瘤进行导航注册。根据导航建立的切除线切除模拟骨肿瘤，并计算切除后的相应骨边缘。由一位不了解切除计划的骨科医生切除水泥模拟肿瘤周围的松质骨来确定最短距离。认为较小的平均边缘差异是准确的。在 95%CI 下进行独立 t 检验，以评估计划边缘和术后边缘之间的测量差异。进行 Bland-Altman 分析，分别比较皮肤和骨基准标记注册之间计划和术后边缘差异的偏差。
总共测量了 84 个总切除边缘，其中 48 个长骨和 20 个骨盆获得了皮肤基准标记，16 个长骨获得了骨基准标记。所有长骨和骨盆切除的计划平均边缘为 10 毫米。我们发现，在切除长骨时，皮肤基准标记和骨基准标记的术后边缘具有相当的准确性（10 ± 2 毫米与 9 ± 2 毫米，平均差异 1 [95%CI 0 至 2]；p = 0.16）。此外，皮肤基准标记的长骨术后边缘与骨盆髋臼上的皮肤基准标记获得的术后边缘的准确性相当（10 ± 2 毫米与 11 ± 3 毫米，平均差异-1 毫米[95%CI-3 至 1]；p = 0.22）。当比较皮肤和骨基准标记注册之间计划和术后边缘差异的偏差时，90%（61/68）的皮肤基准标记和 100%（16/16）的骨基准标记术后边缘落在 2 个标准差内。
在这项初步研究中，皮肤基准标记在尸体模型的皮肤表面和用于计划边缘的 CT 图像上很容易识别。这种技术似乎是在该模型中计划边缘的准确方法，但需要在患者中进行彻底测试，以确定它是否可能比使用骨基准标记更好的临床方法。
在这项初步研究中，使用皮肤基准标记和骨基准标记进行注册获得的边缘相似，且效应量非常小。在任何切除中，模拟肿瘤的边界均未受到侵犯。皮肤基准标记比骨基准标记（解剖标志）更容易识别。如果未来的临床研究表明，使用皮肤基准标记进行注册获得的边缘与使用解剖标志获得的边缘相似，则使用导航和皮肤基准标记而不是骨基准标记可能是有利的。该技术可以减少外科医生用于计划和定位注册点的时间，并提供替代的注册技术，为外科医生提供其他注册方法。
