The posterior approach to the hip in total hip arthroplasty (THA) was first described in 1874. Since then it has undergone several modifications. Most recent changes include the posterior capsulotendinous repair to improve stability, and minimally invasive techniques to improve function. One such short incision technique is the Piriformis-sparing minimally invasive (PSMI) approach. The aim of this thesis was to describe and analyse the approach to establish that it was safe, and to compare it to the standard posterior approach. Initially, a retrospective pilot study was performed comparing the PSMI approach to a control group by the standard posterior approach, with minimum 2 years' follow-up. Then, in a prospective study, radiostereometric analysis (RSA) was used on a small cohort of patients to assess the integrity of repair of the posterior capsulotendinous structures. Stress radiographs taken at 3 months were compared with immediate post-operative controls. A blinded randomised controlled trial (RCT) was commenced to compare the PSMI approach with the standard approach with minimum 2 years' follow-up. A subgroup of this study was analysed to assess the impact of dividing and repairing versus preserving Piriformis, using MRI. The pilot study demonstrated the PSMI approach to the hip was safe. Findings suggested it resulted in less blood loss, shorter inpatient stay and better early function. The RSA study demonstrated that the majority of capsulotendinous repairs remain intact in the PSMI approach, conflicting with other studies. The findings of the RCT failed to support those of the pilot study – the PSMI approach resulted in early improved function, but no difference in any outcomes after 6 weeks when compared to the standard posterior approach.
|Doctor of Philosophy
|Unpublished - 2012