Stemless hip arthroplasty versus traditional implants: a comparative observational study at 30 months follow-up.

Introduction:: The aim of this retrospective case-control study is to evaluate clinical and radiographic results of short stems compared with traditional hip prostheses.

Methods:: 46 short stems (SS) and 50 traditional stems (TS) were selected. All the stems were implanted by the same surgeon using posterior approach because of primary osteoarthritis, post-traumatic osteoarthritis and avascular necrosis. All the patients were compared clinically by Harris Hip Score (HHS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), visual analogue scale (VAS), 12-item Short Form Health Survey (SF-12F/M) and radiographically (offset, CD angle, limb length discrepancy, cup inclination, subsidence, osseointegration, heterotopic ossification). Radiographic evaluations were carried out by 3 different blinded surgeons. A statistical analysis was performed (chi-square, t-test, Mann-Whitney).

Results:: At a mean follow-up of 30 months all the implanted stems were well-positioned and osseointegrated. In both groups there was a marked improvement in pain ( p < 0.001) with a statistically significant advantage in the SS group for WOMAC (90.8 vs. 87.5; p = 0.02) and in part for HHS (93 vs. 91.7; p = 0.18). The radiographic evaluations, with high concordance correlation between the 3 blinded surgeons (ICC consistently >0.80), showed no significant differences in the restoration of the articular geometry, with a reduction of cortical hypertrophy (2% SS vs. 7% TS) and periprosthetic stress-shielding ( p < 0.05) in the SS group. On the other hand, SS were more related to limb length discrepancy (61% vs. 33%; p < 0.05). No major complications were recorded in the 2 groups.

Conclusion:: Short stems were shown to be comparable or better than traditional implants at short-term follow-up.