[Metaphyseal fitting short-stem prosthesis - preliminary results of a prospective single-surgeon series]

Conventional uncemented femoral stems provide good long-term fixation in patients with a wide range of clinical function. However, preservation of bone stock, and minimally invasive approaches have led to exploration into various other implant designs. Short-stem prosthesis focusing on a stable metaphyseal fit have emerged to address these challenges in total hip arthroplasty. The purpose of this study was to evaluate the clinical and radiological results of a newly developed short-stem hip prosthesis AIDA® in context of a single surgeon study.

From February 2009 to December 2013, 72 cementless "AIDA® short stems" (Fa. Implantcast) were implanted by a single surgeon in one study centre via the Watson Jones interval. All patients signed informed consent prior to screening and the study design was approved by the local ethics committee. 51 patients with 52 implants (35 female, 36 male) with a follow-up > 24 months were included in this prospective, controlled clinical trial. The patients were pre- and postoperatively examined clinically and radiological by a specified protocol.

The average patient age at the time of THA was 61 ± 3.2 years (min.-max. 46-68 years). At the last follow-up, the average Harris Hip score increased from 41.4 ± 4.5 preoperatively to 96.8 ± 3.2 points postoperatively. The hospital stay was 9.1 days on average. The X-rays showed in all cases a stable fixation of the stems with full bony integration and no signs of loosening or migration. There were no specific complications relating to the less invasive approach. Postoperatively one periprosthetic fracture was evident. The revision operation into a cementless stem was done without any complications (revisions rate 1.9 %).

The newly developed "AIDA short stem" is a promising hip implant for the young and active patient with osteoarthritis of the hip. The short-term results are encouraging, but nevertheless mid- and long-term results must be further observed on a prospective basis as part of this collective study.