Computer-Assisted Planning and Patient-Specific Instruments for Bone Tumor Resection within the Pelvis: A Series of 11 Patients

Abstract

Pelvic bone tumor resection is challenging due to complex geometry, limited visibility, and restricted workspace. Accurate resection including a safe margin is required to decrease the risk of local recurrence. This clinical study reports 11 cases of pelvic bone tumor resected by using patient-specific instruments. Magnetic resonance imaging was used to delineate the tumor and computerized tomography to localize it in 3D. Resection planning consisted in desired cutting planes around the tumor including a safe margin. The instruments were designed to fit into unique position on the bony structure and to indicate the desired resection planes. Intraoperatively, instruments were positioned freehand by the surgeon and bone cutting was performed with an oscillating saw. Histopathological analysis of resected specimens showed tumor-free bone resection margins for all cases. Available postoperative computed tomography was registered to preoperative computed tomography to measure location accuracy (minimal distance between an achieved and desired cut planes) and errors on safe margin (minimal distance between the achieved cut planes and the tumor boundary). The location accuracy averaged 2.5 mm. Errors in safe margin averaged −0.8 mm. Instruments described in this study may improve bone tumor surgery within the pelvis by providing good cutting accuracy and clinically acceptable margins.

CORR Insights®: Reconstruction After Hemipelvectomy With the Ice-Cream Cone Prosthesis: What Are the Short-term Clinical Results?

“…Preoperative three-dimensional (3-D) planning of the osteotomy may have implications not only for the adequacy of the resection margins, but also for the biomechanical stability and design of the prosthesis [3][4][5][6]. The difficulty remains in how we transfer insights of the preoperative 3-D planning process to the operating field.…”

“…The difficulty remains in how we transfer insights of the preoperative 3-D planning process to the operating field. We have two options if we wish to reproduce this planning in the operative room and increase accuracy: (1) Computer-assisted navigation technologies [3,6] or (2) Patient-specific templates that make a guided osteotomy feasible [4,5].…”

“…These instruments are designed using computer-aided systems and can assist in fitting bonespecific contact surfaces into unique positions on the bony structure of the patient [4,5]. There are two main issues with this technique: (1) The design, manufacturing, and delivery of patient-specific guides and implants can take approximately 3 weeks [5], and (2) mispositioning of the guide can cause inaccuracy during bone cutting [4].…”

“…They also have the worst functional outcomes. When resection methods (with and without reconstruction) are compared to one another, previously published studies [1,[4][5][6] do not agree about which approach is most likely to result in best functional outcomes. One review article likewise suggested that there is no clearly superior reconstructive approach for those patients who undergo internal hemipelvectomies for tumor [7].…”

Additive manufacturing in orthopaedics: Clinical implications

“…The 3D capabilities of computed tomography (CT) and magnetic resonance imaging (MRI) can expand these capabilities significantly. 4,5 However, proprietary hardware, software and services are known to be extremely costly when customised reconstructions are required. 3 This case report demonstrates that the use of 3D printing and rapid prototyping can provide affordable and personalised templates and implants, which are useful in planning and performing these technically difficult surgeries .…”