cells Review Computer Navigation and 3D Printing in the Surgical Management of Bone Sarcoma Robert Allan McCulloch 1, *, Tommaso Frisoni 2,3 , Vineet Kurunskal 4 , Davide Maria Donati 2,3 and Lee Jeys 4   Citation: McCulloch, R.A.; Frisoni, T.; Kurunskal, V.; Maria Donati, D.; Jeys, L. Computer Navigation and 3D Printing in the Surgical Management of Bone Sarcoma. Cells 2021, 10, 195. https://doi.org/10.3390/cells10020195 Academic Editor: Annalisa Santucci Received: 19 December 2020 Accepted: 18 January 2021 Published: 20 January 2021 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). 1 Oncology Arthroplasty Fellow, Royal Orthopaedic Hospital, Birmingham B15 2TT, UK 2 3rd Orthopaedic and Traumatologic Clinic prevalently, Oncologic—IRCCS Rizzoli Orthopaedic Institute, 40126 Bologna,Italy; tommaso.frisoni@ior.it (T.F.); Davide.mariadonati@ior.it (D.M.D.) 3 Biomedical and Neuromotor Sciences Department, University of Bologna, 40126 Bologna, Italy 4 Orthopaedic Oncology Surgeon, Royal Orthopaedic Hospital, Birmingham B15 2TT, UK; vineet.kurunskal@nhs.net (V.K.); lee.jeys@nhs.net (L.J.) * Correspondence: Robert.mcculloch@nhs.net; Tel.: +44-078-2899-4206 Abstract: The long-term outcomes of osteosarcoma have improved; however, patients with metas- tases, recurrence or axial disease continue to have a poor prognosis. Computer navigation in surgery is becoming ever more commonplace, and the proposed advantages, including precision during surgery, is particularly applicable to the field of orthopaedic oncology and challenging areas such as the axial skeleton. Within this article, we provide an overview of the field of computer navigation and computer-assisted tumour surgery (CATS), in particular its relevance to the surgical management of osteosarcoma. Keywords: osteosarcoma; computer-assisted surgery; patient-specific instrumentation; computer navigation 1. Introduction Osteosarcoma (OS) is defined by neoplasms that have the histological characteristics of producing an osteoid and being associated with malignant mesenchymal cells [1]. There are varying histological subtypes, but the vast majority (80–90%) are high-grade OS [2]. In the majority of cases the aetiology is unknown; however, two genetic mutations are associated with OS: a mutation of the retinoblastoma gene, and an autosomic recessive mutation of p53 in Li–Fraumeni syndrome [3]. The overall incidence of OS is 0.2–3/100,000 per year in Europe and its most common anatomical sites are the distal femur, proximal tibia and proximal humerus [4–6]. Ten percent of cases present in the axial skeleton, with the majority originating in the pelvis. This patient subgroup has a higher proportion of patients ages 60 and above [7,8]. Survivorship of OS in extremity localised, non-metastatic disease is 60–70%. However, in metastatic disease, the 5-year overall survival drops to 28–33% [9]. Complete surgical resection remains essential for cure [10], yet there remains some controversy as to the definition of an adequate margin of resection, with evidence that close margins (<5 mm) versus wide margins (>10 mm) did not have an effect on rates of local recurrence [11,12]. Due to the challenges of the surrounding anatomy and the complex three-dimensional structure of the pelvis, a complete resection in the pelvis can be more challenging than in the appendicular skeleton. It has been reported that the probability of an experienced surgeon achieving a 1 cm surgical margin in all three planes on a simulated tumour model of the pelvis was only 52% [13]. The sequelae of inadequate resection are significant, with recurrence rates of 70% and 92% for marginal and intralesional resections, respectively, for OS [14,15]. The uptake in the use of computer navigation in the surgical management of OS is in response to these factors, in a bid to minimise the incidence of inadequate resection margins. Cells 2021, 10, 195. https://doi.org/10.3390/cells10020195 https://www.mdpi.com/journal/cells