Third generation Dual Mobility Cups: could be the future in total hip arthroplasty? A five-year experience with dualis.

BACKGROUND: The concept of dual mobility (DM) is currently approved as a valid option for reducing the risk of dislocation, with an incidence ranging from 0% to 4.6%. The principle is to achieve a high joint stability through a large diameter polyethylene (PE) liner, and to reduce cutting forces due to a "low-friction" head-liner coupling mechanism. METHODS: From March 2015 to March 2020, 138 patients were treated with Dualis Cup (Gruppo Bioimpianti-Peschiera Borromeo, MI, Italy) for a total of 141 implants (three cases were bilateral). The average age at the time of the surgery was 77. Patients' clinical and X-ray follow-up was at 1, 3, 6, 12 months and then once a year. RESULTS: Seven patients (4.9%) had complications which required a second surgery, but only one case (0.7%) of intraprosthetic dislocation (which required cup revision), was directly ascribable to the DM cup. CONCLUSIONS: Improvements in design and materials of the third generation DM cups allowed both to reduce the rate of dislocations in high-risk patients (i.e., patients with neuro-muscular diseases and cognitive disorders, patients needing revisions, osteosynthesis failures, femoral neck fractures) and to achieve a survival rate similar to standard cups, ensuring a range of motion (ROM) very close to the physiological one. In our brief experience, Dualis Cups showed results comparable to those reported in the literature for Dual Mobility. If this data is confirmed by long-term studies, the use of DM cups could be extended even for young patients with high functional demands. (www.actabiomedica.it).

Intercalary allograft reconstruction in a patient with large tibial defect: Case report.

A fit 26 year-old-man presented to our Department with an open fracture of the left tibial shaft (AO 42-C3). The fracture was initially treated with an External Fixator, which was replaced by an intramedullary Grosse Kempf nail after 4 months. In the following year he developed an atrophic non-union and we witnessed the increasing bone resorption at the fracture site which led to the nail breakage. An accurate CT pre-operative planning was made and a revision surgery was successfully performed: the broken nail was removed and intercalary allograft reconstruction was made, using a compressible intramedullary nail. Whereas in literature it is well described how intercalary allografts can be used to fill the massive diaphyseal defects after tumor resections, we assumed it could also be an adequate technique to treat a large bone defect at a non-union site.

Patient specific instrumentation in total knee arthroplasty.

BACKGROUND AND AIM OF THE WORK: The international literature and analysis of the prosthetic registers highlight a significant relationship between the alignment of the components and the survival of prosthetic implants of the knee. The patient specific instrumentation (PSI) technology exploits the data obtained with the MRN for the production of cutting blocks (CB) useful to a TKA. Revisiting the recent international literature, comparing the results of the conventional method and PSI, numerous studies confirm a statistically significant difference of inliers (± 3 degrees) for HKA. The purpose of this retrospective study was to investigate whether these statistically significant difference is also present in our group. METHODS: Postoperative radiographic measures of alignment based on a mechanical limb axis (hip-knee-ankle angle, HKA) of 180° were sought. A range of 180° ± 3° varus/valgus was defined as optimal for mechanical axis. RESULTS: The percentage of knees that had a HKA within ±3° of the desired value was 92.2. CONCLUSION: the CB did accurately produce the desired HKA. The PS system is an effective and reproducible, whose organizational effort is fully justified.