The aims of this study were to determine if an increasing serum cobalt (Co) and/or chromium (Cr) concentration is correlated with a decreasing Harris Hip Score (HHS) and Hip disability and Osteoarthritis Outcome Score (HOOS) in patients who received the Articular Surface Replacement (ASR) hip resurfacing arthroplasty (HRA), and to evaluate the ten-year revision rate and show if sex, inclination angle, and Co level influenced the revision rate. A total of 62 patients with an ASR-HRA were included and monitored yearly postoperatively. At follow-up, serum Co and Cr levels were measured and the HHS and the HOOS were scored. In addition, preoperative patient and implant variables and the need for revision surgery were recorded. We used a linear mixed model to relate the serum Co and Cr levels to different patient-reported outcome measures (PROMs). For the survival analyses we used the Kaplan-Meier and Cox regression model.Aims
Methods
The purpose of this prospective study was to
evaluate the long-term clinical and radiological outcomes of revision of
the femoral component of a total hip replacement using impaction
bone grafting. Femoral revision with an impacted allograft was performed
on 29 patients (31 hips). In all, 21 hips (68%) had grade III or
IV femoral defects according to the Endo-Klinik classification.
A total of 11 patients (12 hips) died before the ten-year follow-up
period. Of the remaining patients, 18 patients (19 hips) were followed
for 10 to 15 years; three further patients died during this time.
None of the 31 stems underwent further revision of their stem. However,
four stems showed extensive subsidence (>
15 mm). One of these patients
had a femoral fracture that required fixation. Three other patients
had a femoral fracture, two of which required fixation and the other
was treated conservatively. Patients with a femoral fracture and/or
severe subsidence had significantly more grade IV defects (six of
seven hips; p = 0.004). One patient needed a closed reduction for
dislocation. Impaction allografting in revision hip surgery gives good long-term
results for femora with grades I, II and III Endo-Klinik-classified
defects. Extensive subsidence and femoral fractures were seen mainly
in patients with grade IV damaged femora.
We report the initial results of an ongoing randomised, prospective study on migration of the Exeter and Elite Plus femoral stems after impaction allografting, as measured by radiostereometry. Clinically, the impaction technique gave good results for both stems. The mean subsidence in the first year was 1.30 mm and 0.20 mm for the Exeter and the Elite Plus stems, respectively. In the second year, the Exeter stem continued to subside further by a mean of 0.42 mm, while the Elite Plus stem did not do so. Subsidence of the Exeter stem correlated with deficiency of bone stock as graded on the Gustilo and Pasternak scale. This correlation was not found for the Elite Plus stem. None of the other parameters which were studied predisposed to subsidence. There was no significant association between the amount of subsidence and the radiological appearance of the graft for either stem. Our findings do not support the theory that radial compression, due to subsidence of the Exeter stem, is the essential stimulus for remodelling in impaction allografting.
