Neck modularity has been proposed to improve THA accuracy, thanks to the close restoration of anatomy, however it has been associated with issues like early breakages or corrosion. Our Hospital has been using neck modularity since the 90s, so we analyzed retrospectively implants performed between January 2000 and December 2014. The minimum follow up was 1Y. The cohort was composed of 1,033 THAs or 951 patients (82 bilateral), of which 643 females and 390 males. Average patient age was 67.7Y. THA indications were primary Osteoarthritis (80.9%), Fracture (9.0%), Congenital Dysplasia or Congenital Luxation (4.2%), Osteonecrosis (3.2%), other causes (2,7%). The stems used were all cementless, 381 anatomically shaped (36.9%), 635 straight (61.5%), 17 short MIS (1.6%). All necks used were made of Titanium alloy. 419 implants (40.5%) were manufactured by Wright Medical, while 614 (59.5%) were produced by Adler Ortho. A total of 37 revisions has been reported, mainly due to periprosthetic fractures (32.4%), luxation (24.3%), implant mobilization (18.9%) and implant breakage (16.2%). We have recorded 3 modular neck breakages. 4 patients required re-revisions, because of luxations (3) and neck breakage (1). The overall survival rate was 96.4%. We did not observe any component corrosion, probably thanks to the exclusive use of Titanium necks. We had a neck breakages rate of 0.29% and a luxation rate of 0.87%, lower than normally reported in the literature. In conclusion, our experience suggests as neck modularity could be a safe and effective way to reconstruct the proximal femur in THA patients.
In a retrospective study, FE-based bone strength from CT data showed a greater ability than aBMD to discriminate proximal femur fractures versus controls. Personalised Finite Element (FE) models from Computed Tomography (CT) data are superior to bone mineral density (BMD) in predicting proximal femoral strength Summary Statement
Introduction
Undisplaced or minimal displaced medial neck femoral fractures are treated with canulated screws either in young or in elderly patients with good functional capacity, without severe comorbidity and cognitive impairment. We also perform this procedure in patients with very low daily activities and affected by severe comorbidity, with the aim to reduce pain. We reserve total hip replacement in middle-advanced age, with good level of functional activity and adequate bone-stock. We use bipolar hemiarthroplasty in patients that need early mobilization for the presence of comorbidities that could worsen. We prefer cemented bipolar hemiarthroplasty, as it gives an optimal primary stability, without press-fit. We prefer to utilize bipolar hemiarthroplasty with memory shape stem F.G.L. (Fig.1) in high risk patients (ASA classification). In fact the use of cement prolongs duration of surgery and is associated with higher perioperative mortality from cardiopulmonary complications. This stem in its metaphyseal region has 10 tabs, made of a Nitinol alloy (Ni-Ti). The feature of this alloy is to enlarge when brought to a certain temperature. When F.G.L. stem is mantained at 4° - 7° C the Nitinol (r) tabs are in the “restrained” configuration. Just at the time of surgery procedure, the stem is taken out of the refrigerator and inserted into the femoral diaphysis. At corporeal temperature, the Nitinol tabs enlarge, compressing the metaphyseal cancellous femoral region and give an immediate primary stability. We report clinical and radiological results of 15 patients (mean follow-up: 8 months) that underwent surgical procedure of bipolar hemiarthroplasty with F.G.L. stem in our department from March 2008 to December 2009. We had no perioperative complications and the results overlapped those of patients that underwent standard cemented bipolar hemiarthroplasty. The advantage of the use of F.G.L. stem is that it allows an immediate primary stability without searching an extreme press-fit. The disadvantage is the higher cost respect a standard cemented bipolar hemiarthroplasty. Therefore its use should be limited to those patients in which the surgery time must be contained for severe comorbidity, or in patients in which specific cardio-pulmonary complaints make dangerous the use of cement.