Background: Currently, total hip replacement (THR) is most commonly performed via a posterior or a direct lateral approach. We compared the one year postoperative outcome of cementless THR using the both approaches in a prospective, randomized trial.
Methods: A prospective 1:1 randomization scheme was implemented to allocate 60 patients with unilateral osteoarthritis. Patients in the lateral approach group were in median 59 years old, in 50% female and had a median BMI of 27 kg/m2 versus in median 55 years, 47% females and a median BMI of 29 kg/m2 in the posterior approach group. Outcome assessment was performed one day before surgery and 3 months, 6 months and one year after surgery, respectively, using the intra-individual Harris Hip score (HHS) improvement at one year as primary objective. Sample size calculation was based on the assumption of a minimum clinically relevant difference of 5 points and a standard deviation of 6 points in the HHS total score. WOMAC and SF-36 served as secondary objectives.
Results: Patients started with a median HHS of 50 points after lateral approach versus 46 points after posterior approach and showed a median HHS of 95 points versus 94 points one year after surgery. We found a slight tendency towards the posterior approach, but no significant difference in the intraindividual HHS improvement at all the pre- and post-operative assessment points between both treatment groups (Wilcoxon p=0.115 at 3 months, p=0.191 at 6 months and p=0.207 at one year). A comparable tendency was found in the intraindividual WOMAC improvement without statistical significance (Wilcoxon p=0.749). In contrast the SF-36 physical scales were slightly but again not significantly better after lateral approach at the one year assessment (86% versus 80%,Wilcoxon p=0.674).
Conclusions: Not any (algo-) functional and psychometric endpoint investigated showed a statistical significant difference between patients after lateral versus posterior approach for THR.
We conclude that motivation and other patient related factors, the implant and the surgeon itself influence the result much more than the approach used for total hip replacement.
