Clinical and radiographic evaluations of titanium trabecular metal components manufactured by 3D printing for primary total hip arthroplasty: a 5-year follow-up

Objective To explore the mid-term efficacy of porous titanium trabecular metal (TTM) components manufactured by 3D printing for primary total hip arthroplasty (THA). Methods Enrolled for this prospective clinical trial were 19 patients (20 hips) who were to receive primary THA from May 2012 to June 2013 at Department of Orthopaedics and Traumatology, Puai Hospital. Of them, 9 patients (10 hips) used 3D printing porous TTM for acetabular prosthesis in primary THA while the other 10 patients (10 hips) used Pinnacle acetabular prosthesis. At 5 years after operation, clinical and radiographic evaluations were conducted to assess acetabular component stability, osseointegration in the acetabulum-bone interface, and osteolysis incidence. Harris scores were used to assess the hip functions. Results The follow-up duration for all the patients averaged 5 years. By the Harris scores, 8 cases were excellent and 2 good in the TTM group while 9 excellent and one good in the Pinnacle group. The Harris scores were significantly improved from preoperative 48.2+5.5 to 92.8+3.1 at 5 years after operation in the TTM group and significantly from 46.5±8.7 to 94.6±2.9 in the Pinnacle group (P 0.05). Radiographic evaluation showed stable acetabular components, fine osseointegration, and no implant loosening or osteolysis. Two hips in the TTM group had a postoperative radiolucent line which disappeared 6 months later. The 5-year survival rate of the acetabular components was 100% for both groups, taking prosthetic loosening or revision as the end point. Conclusion The 3D printing TTM has shown excellent mid-term efficacy but its long-term efficacy needs further follow-up study. Key words: Arthroplasty, replacement, hip; Titanium; Follow-up studies; Three-dimensional printing; Electron beam melting