Among the advanced technology developed and tested for orthopaedic surgery, the Rizzoli (IOR) has a long experience on custom-made design and implant of devices for joint and bone replacements. This follows the recent advancements in additive manufacturing, which now allows to obtain products also in metal alloy by deposition of material layer-by-layer according to a digital model. The process starts from medical image, goes through anatomical modelling, prosthesis design, prototyping, and final production in 3D printers and in case post-production. These devices have demonstrated already to be accurate enough to address properly the specific needs and conditions of the patient and of his/her physician. These guarantee also minimum removal of the tissues, partial replacements, no size related issues, minimal invasiveness, limited instrumentation. The thorough preparation of the treatment results also in a considerable shortening of the surgical and of recovery time. The necessary additional efforts and costs of custom-made implants seem to be well balanced by these advantages and savings, which shall include the lower failures and revision surgery rates. This also allows thoughtful optimization of the component-to-bone interfaces, by advanced lattice structures, with topologies mimicking the trabecular bone, possibly to promote osteointegration and to prevent infection. IOR's experience comprises all sub-disciplines and anatomical areas, here mentioned in historical order. Originally, several systems of Patient-Specific instrumentation have been exploited in total knee and total ankle replacements. A few massive osteoarticular reconstructions in the shank and foot for severe bone fractures were performed, starting from mirroring the contralateral area. Something very similar was performed also for pelvic surgery in the Oncology department, where massive skeletal reconstructions for bone tumours are necessary. To this aim, in addition to the standard anatomical modelling, prosthesis design, technical/technological refinements, and manufacturing, surgical guides for the correct execution of the osteotomies are also designed and 3D printed. Another original experience is about en-block replacement of vertebral bodies for severe bone loss, in particular for tumours. In this project, technological and biological aspects have also been addressed, to enhance osteointegration and to diminish the risk of infection. In our series there is also a case of successful custom reconstruction of the anterior chest wall. Initial experiences are in progress also for shoulder and elbow surgery, in particular for pre-op planning and surgical guide design in complex re-alignment osteotomies for severe bone deformities. Also in complex flat-foot deformities, in preparation of surgical corrections, 3D digital reconstruction and 3D printing in cheap ABS filaments have been valuable, for indication, planning of surgery and patient communication; with special materials mimicking bone strength, these 3D physical models are precious also for training and preparation of the surgery. In Paediatric surgery severe multi planar & multifocal deformities in children are addressed with personalized pre-op planning and custom cutting-guides for the necessary osteotomies, most of which require custom allografts. A number of complex hip revision surgeries have been performed, where 3D reconstruction for possible final solutions with exact implants on the remaining bone were developed. Elective surgery has been addressed as well, in particular the customization of an original total ankle replacement designed at IOR. Also a novel system with a high-tibial-osteotomy, including a custom cutting jig and the fixation plate was tested. An initial experience for the design and test of custom ankle & foot orthotics is also in progress, starting with 3D surface scanning of the shank and foot including the plantar aspect. Clearly, for achieving these results, multi-disciplinary teams have been formed, including physicians, radiologists, bioengineers and technologists, working together for the same goal

In patients with developmental dysplasia of the hip (DDH) chronic joint dislocation induces remodeling of the soft tissue with contractures, muscle atrophy, especially of the hip abductors muscles, leading to severe motor dysfunction, pain and disability (1). The aim pf the present work is to explore if a correct positioning of the prosthetic implants through 3D skeletal modeling surgical planning technologies and an adequate customized rehabilitation can be beneficial for patients with DDH in improving functional performance. The project included two branches: a methodology branch of software development for the muscular efficiency calculation, which was inserted in the Hip-Op surgical planning system (2), developed at IOR to allow surgical planning for patients with complex hip joint impairment; and a clinical branch which involved the use of the developed software as part of a clinical multicentric randomized trial. 50 patients with DDH were randomized in two groups: a simple surgical planning group and an advanced surgical planning with muscular study group. The latter followed a customized rehabilitation program for the strenghtening of hip abductor muscles. All patients were assessed before surgery (T0) and at 3 (T1) and 6 months (T2) postoperatively using clinical outcome (WOMAC, HHS, ROM, MMT, SF12, 10mt WT) and instrumental measures (Dynamometric MT). Pre- and post-operative musculoskeletal parameters obtained by the software (i.e., leg length discrepancy, hip abductor muscle lengths and lever arms) using Hip-Op during the surgical planning were considered. One Way ANOVA for ROM measurement showed a significant improvement at T2 in patients included in experimental group, as well as WOMAC, HHS and SF12 score. The Dynamometric MT score showed significant differences between at T2 (p<0.009). Spearman's rank correlation coefficients showed a significant correlation between both pre- and post-operative abductors lever arm (mm) and hip abductor muscle strength at T2 (ρ = −0.55 pre-op and ρ = −0.51 post-op, p p<0.012 and p<0.02 respectively) and between the operated pre-postoperative leg length variation (mm) and the hip abductor muscle strength (ρ = −0.55, p p<0.013). Results so far obtained showed an improvement of functional outcomes in patients undergoing hip replacement surgery who followed therapeutic diagnostic pathway sincluding a preoperative planning including the assessment of the abductiors lever arm and a dedicated rehabilitation program for the strenghtening of abductios. Particularly interesting is the inverse relationship between the strength of the hip abductor muscles and the variation of the postoperative abductor lever arm