BACKGROUND AND PURPOSE: We undertook a prospective clinical trial assessing the Nanos® short stem cementless femoral prosthesis. The primary objective was to assess the implant for subsidence and rotational stability via Radiostereometric Analysis (RSA).  The secondary objective was to assess functional outcome.

PATIENTS AND METHODS: 28 patients undergoing unilateral Total Hip Arthroplasty (THA) using ashort stem prosthesis were compared to a control group using a standardCorail® stem.Both stems were uncemented and the procedures performed by the same surgeons. Data collection points were preoperative, 3 months and 2 years post operatively. RSA radiographs were performed to assess subsidence and rotational stability.  Functional analysis was undertaken using the Oxford Hip Score (OHS).

RESULTS: Theshortstem showed a median subsidence of 0.12mm at 3 months witha further 0.09mm in the 3–24 month interval.Medianposterior translation of prosthesis head (retroversion) was 0.21mm at 3 months, with a further 0.07mm in the 3–24 month interval. Varus/valgus displacements measured were minimal. The mean OHS improved from 23 preoperatively to 44 at 3 months and 43 at 24 months review. There were 2 early revisions: one for leg length discrepancy and one for early loosening secondary to under–sizing of the implant. There were no significant differences to the control group.

INTERPRETATION: THA patients with this stem demonstrated good stability and excellent short–term functional results, however the high revision rate in our series remains a concern.