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

Introduction. The management of periprosthetic pelvic bone loss is a challenging problem in hip revision surgery. This study evaluates the minimum 10-year clinical and radiographic outcome of major column structural allografts combined with the Burch-Schneider antiprotrusio cage for acetabular reconstruction. Methods. From January 1992 to August 2005, 106 hips with periprosthetic osteolysis underwent acetabular revision using massive allografts and the Burch-Schneider antiprotrusio cage. Forty-five patients (49 hips) died for unrelated causes without further surgery. Fifty-nine hips in 59 patients underwent clinical and radiographic evaluation at an average follow-up of 15.1 years. There were 17 male and 42 female patients, with age ranging from 29 to 83 years (mean 59). Results. Ten hips required rerevision because of infection (3), aseptic loosening (6), and flange breakage (1). Moreover, 4 cages showed x-ray signs of instability with severe bone resorption. The survivorship of the Burch-Schneider cage at 21.9 years with removal for any reason or radiographic migration and aseptic or radiographic failure as the end points were 76.3 and 81.4, respectively. The average Harris hip score improved from 33.2 points preoperatively to 75.7 points at the latest follow-up (p < 0.001). Discussion. In hip revision surgery, severe deficiency of pelvic bone stock is a critical concern because of the difficulty in providing a stable and durable fixation of the prosthesis. Although antiprotrusio cages have a limited role in acetabular revision, the use in association with massive allografts in extended bone loss demonstrated highly successful long-term results, enabling bone stock restoration and cup stability

Introduction. The objective of this study was to compare the performance of the Explant Acetabular Cup Removal System (Zimmer), which has been the favored system for many surgeons during hip revision surgery, and the new EZout Powered Acetabular Revision System (Stryker). Methods. 54mm Stryker Trident® acetabular shells were inserted into the foam acetabula of 24 composite hemi-pelvises (Sawbones). The hemi-pelvises were mounted on a supporting apparatus enclosing three load cells. Strain gauges were placed on the hemipelvis, on the posterior and the anterior wall, and on the internal ischium in proximity to the acetabular fossa. A thermocouple was fixed onto the polar region of the acetabular component. One experienced orthopaedic surgeon and one resident performed mock revision surgery 6 times each per system. Results. Statistical analysis was conducted using Tukey's range test (HSD). The maximum force transferred to the implant was more than 4X lower with the EZout System regardless the surgeon experience (p=1.0E-08). Overall, recorded strains were lower for the EZout System with the higher decrease in strain (5X) observed at the posterior wall region(p=2E-08). The temperature at the interface was higher for the EZout System but never more than 37°C. Total removal time was on average reduced by a third with the EZout System (p=0.01). The calculated torque was lower for the EZout System. The amount of foam left on the cup after removal, which mimics the compromised bone, was 2.5X higher on average for the Explant System with most of the foam concentrated in the polar region. Lastly, it was observed that the polar region of each implant was reached by rotating the EZout System handpiece within a very narrow cylinder of space centered along the axis of the acetabular component compared to the Explant System, which required movement of the pivoting osteotomes within a large cone-shaped operating envelope. Discussion. Quantitatively, the EZout System required lower force, producing lower strains in the surrounding composite bone. Higher impact forces and associated increased strains may increase fracture risk. Qualitatively, the Explant System required a greater cone of movement than the EZout System requiring more space for the surgeon to leverage the handle of the tool. In addition, both surgeon and resident felt substantially greater exhaustion after using the Explant System vs. the EZout System. The resident compensated for the increased workload of the Explant with time, the experienced surgeon with force. The learning curve for both experienced surgeon and resident was also much shorter with the EZout System as shown by the close force values between the experienced surgeon and resident. Conclusion. Based on the results of this in vitro model, the EZout Powered Acetabular Removal System may be a reasonable alternative to manual removal techniques

Background. Periprosthetic osteolysis is the most common long-term complication of a total joint arthroplasty, often resulting in aseptic loosening of the implant. As we aim at developing a safe and minimally invasive implant refixation procedure, thorough characterisation of the properties of the periprosthetic tissue is needed. Methods. In this pilot study, the periprosthetic tissue of eleven patients undergoing hip revision surgery due to aseptic loosening was obtained. Histology, confocal microscopy, atomic force microscopy (AFM) and nanoindentation were performed to structurally and mechanically characterise the tissue. The study was approved by the Medical Ethical Committee of the Leiden University Medical Center. Results. Using a Sirius Red staining and Movat staining, samples were shown to contain collagen fibers and a ground substance consisting of glycosoaminoglycans and mucopolysaccharides. However, the relative proportions of these tissue components differed between as well as within samples. Confocal microscopy revealed differences in collagen fiber orientation and thickness between tissues. Certain samples showed increased collagen staining intensity as well as increased fiber directionality, indicating higher degrees of tissue maturation. Using AFM and nanoindentation, the Young's modulus of the tissue was determined, which is a measure of tissue stiffness. The ranges of Young's moduli observed (generally 0–250 kPa) were relatively low when compared to other collagen-rich soft tissues (e.g. 500 kPa in skin and even 25 MPa in pericardium). Since the periprosthetic tissue develops at a site of friction, cells at the bone-implant interface seem not able to produce a matrix with optimal strength and properties. Conclusions. This study provides new insights on the structural organization and mechanical properties of the periprosthetic tissue. Large inter-patient as well as intra-patient variations in tissue characteristics at all levels studied were observed, which strengthens the need for further research and underscores the need for tailored solutions in the field of treating aseptic loosening

Introduction. We present our experience of the coned hemi-pelvis (‘ice-cream’ cone) implant, using an extended posterior approach to the hip joint, in the management of pelvic bone loss and pelvic discontinuity. Methods. Retrospective study conducted utilising a prospectively collected database. Patients who underwent an ice-cream cone reconstruction between August 2004 – September 2011 were identified. All had a posterior approach to the hip. Femur prepared in the standard fashion. A variety of femoral components used. Demographic data was recorded along with the indication for surgery and outcomes. Results. 16 patients identified. Mean age was 62.2 years. 5 (31.25%) male. 11 (69.75%) female. Indications included; multiple hip revision surgery 4(25%); post Gridlestones for severe hip dysplasia 1 (6.25%); peri-acetabular metastatic deposits 11 (68.75%) from breast, renal, endometrial, prostatic, myeloma primary malignancies. Mean follow-up was 32.06 months. Complications; 1 intra-operative death from tumour embolus; 1 dislocation; 1 superficial surgical site infection. 3 deaths from their primary malignancy. Mean time from prosthesis implantation to death was 14.5 months. All patients at last follow-up were mobilizing. No implant has needed to be revised. Discussion. Pelvic bone loss provides reconstructive challenges. The coned hemi-pelvis is simple to make, easy and versatile to use even when there is little pelvis remaining. It provides a method of negotiating hip reconstruction in patients with severe pelvic bone loss. Orthopaedic surgeons are familiar with the posterior approach to the hip. The ice-cream cone implant can therefore be placed with ease using this well-known approach to the hip

Metal-on-metal (MOM) hip arthroplasty, including resurfacing, has become the subject of recent research and debate. There is the perceived benefit of improved wear rates of bearing surfaces leading to superior durability and performance of these types of implant. An associated feature of MOM bearing surfaces is the generation of metal ions. These can have local and systemic cytotoxic effects. An immunoloigical response has been suggested, however, metal wear debris may cause direct damage to cellular DNA. Studies have shown that release of these ions is related to bearing diameter and component alignment. However, little is known about the relationship between metal ion levels and implant survivorship. The MHRA has published guidelines on the follow-up of patients with MOM implants including measurement of serum ion levels and cross sectional imaging. Between February 2001 and November 2009, 135 patients (164 hips) had MOM resurfacing arthroplasty at our institution. We report a retrospective analysis of the data generated by review of these patients. Of the 135 patients, 91 were identified for clinical review. Each patient had serum metal ion levels measured, plain AP radiographs of the pelvis examined and, in the presence of raised metal ions, a Metal Artefact Reduction Sequence (MARS) MRI performed. 27 patients (35 hips) had raised metal ion levels (Cobalt and Chromium). Patients with raised metal ion levels had a mean acetabular cup inclination of 52.7 degrees compared with a mean inclination of 48.6 degrees in patients with normal ion levels (p<0.05). MARS MRI in the raised ion group revealed 9 patients with appearances suggestive of ALVAL. A number of these patients had hip revision surgery with the remainder awaiting potential revision. These findings reflect current evidence suggesting a relationship between sub-optimal component position and raised metal ion levels and an increased rate of ALVAL