Purpose This paper aims to fill a research gap by presenting design and 3D printing guidelines and considerations which apply to the development process of patient-specific osteotomy guides for orthopaedic surgery. Design/methodology/approach Analysis of specific constraints related to patient-specific surgical guides design and 3D printing, lessons learned during the development process of osteotomy guides for orthopaedic surgery, literature review of recent studies in the field and data gathered from questioning a group of surgeons for capturing their preferences in terms of surgical guides design corresponding to precise functionality (materializing cutting trajectories, ensuring unique positioning and stable fixation during surgery), were all used to extract design recommendations. Findings General design rules for patient-specific osteotomy guides were inferred from examining each step of the design process applied in several case studies in relation to how these guides should be designed to fulfill medical and manufacturing (fused deposition modelling process) constraints. Literature was also investigated for finding other information than the simple reference that the surgical guide is modelled as negative of the bone. It was noticed that literature is focussed more on presenting and discussing medical issues and on assessing surgical outcomes, but hardly at all on guides’ design and design for additive manufacturing aspects. Moreover, surgeons’ opinion was investigated to collect data on different design aspects, as well as interest and willingness to use such 3D-printed surgical guides in training and surgery. Practical implications The study contains useful rules and recommendations for engineers involved in designing and 3D printing patient-specific osteotomy guides. Originality/value A synergetic approach to identify general rules and recommendations for the patient-specific surgical guides design is presented. Specific constraints are identified and analysed using three case studies of wrist, femur and foot osteotomies. Recent literature is reviewed and surgeons’ opinion is investigated.

Metallosis is an adverse event developed in relation with an orthopedic implant. It was brought into attention by metal on metal total hip arthroplasty. Lately, cases were diagnosed in total knee, total elbow, and spinal surgery. Metallic debris - released because of wear or corrosion - start an inflammatory response in a chronic condition. Beside local effects, systemic effects are also described; among them toxic effects, neurological and psychiatric, alteration in thyroid and heart function, skin rushes and discoloration. Diagnosis is helped by x-ray examination but is based on fluid aspiration with ions level determination and histological examination. Osteolysis phenomena induced by metallosis may compromise bone ingrowth and promote implant loosening; as result bone stock may be compromised. The cases we present have a particular development pattern; each of them was initiated as a result of atypical behavior of the implants. Two of them necessitated bone grafting in order to replace the reduced bone stock and all three required revision surgery. The cases emphasize the diagnosis methodology and the possible complications encountered during orthopedic implant surgery.

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The paper reports the use of advanced engineering tools, techniques and manufacturing process for the preoperative planning, visualization and simulation of complex osteotomy of a diabetic foot (Charcot osteoarthropathy). Two case studies focused on the same clinical data are illustrating the use of medical modeling techniques, reverse engineering and Additive Manufacturing technology in the development of 3D printed anatomical model and customized surgical cutting guides, as well as the use of Augmented Reality (AR) tools for enhancing the communication and information exchange between surgeons, and between surgeons and engineers. A good and accurate communication surgeon-engineer in identifying and selecting anatomical landmarks and supporting surfaces, in establishing the resections trajectories and K-wires positions proved mandatory for the guides’ design process. The importance of using both 3D virtual models, AR models and physical models as collaboration tools is also discussed.

The study presented in the current paper was designed to investigate periprosthetic bone remodeling associated with two cementless HA coated stem models, ABG-II (Stryker) and Corail (DePuy), randomly implanted in 40 active patients at Colentina Clinical Hospital,Romania. Anteroposterior with neutral rotation and Lequesne profile radiographs of both hips were taken and several data were recorded: acetabular angle, rotation center of the hip, rotation center height with respect to the greater trochanter tip, femoral cortical thickness, cortico-medullary index at three areas (lesser trochanter (LT), 8 and 12 mm distal to LT), and osteoporosis severity according to the Singh index. The presence of osteolytic lesions in the proximal femur was assessed according to the scale proposed by Goetz in the radiographs obtained at the end of the follow-up (1 to 5 years). The radiological results showed that all stems were stable, and no evolutive radiolucent lines have been observed. We also have noticed minimal remodelling changes in 7 hips (36.61%), with minor cancellous bone densification mainly in zones 2 and 6, without cortical hypertrophy or osteoporosis. A decreased bone density in zones 1 and 7, secondary to stress-shielding, has been evident in 5 hips. Stem subsidence has been similar to that reported in literature with other hydroxyapatite coated designs.