Abstract
Aims
To assess the early subsidence rate of the femoral stem for patients who had collarless Corail total hip replacement.
Methods
Consecutive data was collected retrospectively between August 2007 and December 2009 for patients who had collarless Corail total hip replacement. Radiographic assessment of the degree of subsidence, calcar resorption, stem angulation, canal fill ratio and loosening of the stem were measured. Post operative pain, dislocation and stem revision surgery were also evaluated.
Results
48 patients were identified, providing 51 hips for the study. There were 22 male and 26 female. The mean age 64.2 years (range 38-77). Post-operative radiographs were taken at day 1, 6 weeks and one year post-operatively (range 10-18 months, mean 12.7).
Significant subsidence was defined as 3 or more millimetres, we identified two patients with subsidence between 3-5mm, one patient with 6mm and two patients with 10mm subsidence at one year post-operatively.
In the 5 patients with subsidence post-operatively, all significant subsidence occurred within the first 6 weeks.
Canal fill ratio was measured in all patients; in the non-subsided group the ratio was an average of 72% in the lower third of the stem and 84% in the middle third. In the subsided group 75% in the lower third of the stem and 81% in the middle third, which we felt was clinically insignificant.
There was no dislocation or revision for septic loosening. One patient with 10mm subsidence had liner revision for dissociation but the stem was well fixed and not revised.
All patients who had significant subsidence still had functioning implants with no pain, revisions for subsidence or features of loosening.
Discussion
There were no radiological features predictive of subsidence in our patients.
Subsidence may be due to lack of compliance in some patients with partial weight bearing and increased Body Mass Index.
