Enhancing precision in limb-salvage surgery : proof-of-concept study of an innovative multifunctional...

Achieving tumour-free margins and precise prosthetic alignment remains an important challenge in limb-salvage surgery (LSS). Malalignment can compromise limb function and implant longevity, whereas inadequate margins increase the risk of local recurrence. Therefore, this study aims to develop a novel patient-specific guide (PSG) concept that integrates both osteotomy and prosthetic alignment into a single, user-friendly platform.

A multifunctional PSG was developed, composed of two primary components: a patient-specific insert that is precisely contoured to the patient's bone anatomy, and a reusable universal frame that envelops the patient-specific element. The universal frame serves as a central platform to attach auxiliary instrumentation guides that facilitate osteotomy, reaming, and prosthetic alignment. A proof-of-concept study was conducted on ten cadaveric femora. Following CT imaging, virtual preoperative planning was performed in a 3D environment. The patient-specific parts of the guide were 3D-printed based on the virtual osteotomy and prosthetic alignment planes. The guide system was sequentially applied to perform the osteotomy and prosthesis placement on each specimen. Accuracy was assessed by comparing postoperative CT scans to the preoperative virtual plans, quantifying alignment and resection errors across all planes.

The PSG achieved sub-degree accuracy in coronal and sagittal alignment, with median deviations of 0.4° in both planes and a median rotational deviation of 1.2° (IQR 0.2° to 2.2°). Resection height deviation was 2.4 mm (IQR 1.9 to 3.6), with 90% of cases within a 6 mm margin. No significant correlation was observed between angular and translational errors, indicating no cross-dimensional propagation of error.

This cadaveric proof-of-concept study demonstrates that this innovative multifunctional PSG enables precise intraoperative execution of virtual preoperative plans. By integrating both resection and prosthetic alignment into a single, user-friendly, and cost-effective platform, it addresses an unmet need in limb salvage surgery and could support precision-driven standardization in oncological limb reconstruction.