Total hip revision surgery in cases with previous multiple reconstructive procedures is a challenging treatment due to difficulties in treatment huge bone defects with standard revision prosthetic combinations. A new specially made production system in Electron-Beam Melting (EBM) technology based on a precise analysis of patients' preoperative CT scans has been developed. Objectives of design customization in difficult cases are to correctly evaluate patient's anatomy, to plan a surgical procedure and to obtain an optimal fixation to a poor bone stock. The 3D Printing (EBM) technology permits to create an extremely flexible patient matching implant and instrument, with material performances not viable with standard manufacturing process. Dedicated visual 3D tools and instrumentations improve implants congruency according to preoperative plan. Primary stability is enhanced and tailored on patient's anatomy by means of press-fit, iliac stems and the high friction performances of Trabecular Titanium matrix. The use of bone screws and their position is designed to enhance primary stability, even in critical bone conditions, avoiding implant stress shielding and allowing bone integration. 4 cases (2 men and 2 women) of acetabular customized implants were performed. Mean age at surgery was 51.5 years (range 25–72). Patients were reviewed clinically and radiographically at follow-up.BACKGROUND
METHODS
Between October 2001 and December 2010, 143 patients with developmental dysplasia underwent hip replacement surgery using a conical stem with modular necks (MODULUS) and titanium (Delta PF) and trabecular titanium cups system (Delta TT primary cups) (Lima Corporate, Villanova di San Daniele del Friuli, Italy), with ZTA/ZTA bearing (Ceramtec, Germany). 30 (21.0%) patients had both hips replaced, for a total of 173 implants. Mean age at the time of surgery was 55 years (range 22–81 years). Dysplasia evaluation was based on the Crowe score (6): 66 (38.1%) hips were classified as 1, 50 (28.9%) as 2, 33 (19.1%) as 3 and 24 (13.9%) as 4. Mean follow-up was 87 months (range 36–146 months); average Harris Hip Score increased from 42 (range 23–65) preoperatively to 92 (range 76–100) at the last follow-up. Stem revision was required in two cases. Cup revision was necessary in one case, for failed osteointegration. A postero-lateral approach was used in all cases, with patients lying in a lateral decubitus position. Shortening femoral osteotomy was performed in 5 (2.9%) cases for implant reduction due to excessive tension: oblique osteotomy was employed in 3 cases, using the stem as a fixation device, while subtraction Z-osteotomy with two Dall-Miles cables was used in the other 2 cases. Supra-acetabular bone grafting was performed in 3 cases. In all cases, the cup was implanted at the level of the paleo-acetabulum or in the area between the paleo- and neo-acetabulum. Head diameters were 28 mm in 54 (31.2%) cases, 32mm in 84 (48.6%) cases and 36mm in 35 (20.2%) cases. The association of Modulus stem and Delta TT cups showed good long-term clinical and radiographic results, with a Kaplan-Meier survivorship of 98.8% at 12 years (95% CI, 97.1%-100%).
The project of a modular, double-conicity stem is born from the need to obtain primary stability and correct osseointegration in patients with developmental hip dysplasia, or proximal femoral dysmorphisms requiring a femoral shortening osteotomy or presenting characteristics of non-adaptability to single-conicity or straight stems. Such an implant could also be employed in femoral nail failures, or lateral femoral neck fractures requiring prosthetic substitution. To assess implantability of the new double-conicity stem in cadaver femurs, determining “fit and fill” and the behaviour of femoral cortical bone by means of Rx, CT and pre- and post-implantation mechanical testing.Introduction
Aim of the study
Managing severe periacetabular bone loss during revision total hip arthroplasty (THA) is a challenging task. Multiple treatment options have been described. Delta Revision Trabecular Titanium™ (TT) cup is manufactured by Electron Beam Melting (EBM) technology that allows modulating cellular solid structures with an highly porous structure were conceived to rich the goals of high bone ingrowth and physiological load transfer. The caudal hook and fins ensure additional stability and the modular system allows the surgeon to treat bone defects in the most complex revisions. Entirely modular, the system can meet all intra-operative needs thanks to a customized implant construction. The aim of this prospective study is to evaluate the short to mid-term clinical and radiographic outcomes of this acetabular revision cups. We prospectively assessed clinical and radiographic results of 31 cases of acetabular revisions that were performed from June 2007 and March 2012 by Delta TT Lima Revision system. The mean age of patients was 69.5 years (range 29–90). The causes of revision were aseptic loosening in 22 cases (71.0%), periprosthetic acetabular fractures in 4 cases (13.0%), multiple dislocation of the primary implant in 3 cases (9.6%) and outcome of infection in 2 cases (6.4%). Stem revision was performed in 11 cases (35,4%). In 24 cases bone impaction grafting was used to fill cavitary defects (Paprosky 2B-3A); in 7 cases TT augments were used with the same aim. The average follow-up was 32 months (range 12–69).INTRODUCTION
MATERIALS AND METHODS
