[Bone tissue response to the echelon-type uncemented femoral component in revision total hip arthroplasty (THA)]

We present the preliminary, short-term results of a cohort study of revision THA focused on aseptic loosening and aimed at assessing the metadiaphyseal bone ingrowth biological response of an uncemented femoral implant with an extensive porous coating.

The clinical, X-ray and personal satisfaction outcomes (SF-36) of four patients were assesessed. We had performed four exchange THAs due to a diagnosis of clinical and radiographic aseptic prosthetic loosening, with symptoms of anterior thigh pain. Three THAs were primary and one was a hemiarthroplasty. Mean follow-up after the prosthetic exchange was 41.5 weeks.

As of postoperative week six, a radiographic improvement of the bone appearance was seen due to mineralization and decrease in the radiolucent areas in the interfaces. As of week 20, variable degrees of bone ingrowth were seen. No femoral subsidence has occurred and anterior thigh pain was relieved in all cases.

Stem size, stiffness,stiffness, the geometry and the extension of the porous coating seem to affect bone remodeling. Implants with an extensive porous-coated surface seem to assure a reliable, long-term fixation and provide a circumferential seal against debris.