Abstract
Moderate to severe acetabular bone loss in revision hip arthroplasty is challenging. Various treatment options are available but the medium to long term results have not been encouraging. The porus tantalum uncemented cup may be used successfully to address moderate to severe bone loss in acetabulum revision surgery.
We report a single surgeon series. Between December 2003 and June 2007, 39 patients (43 hips) underwent hip revision surgery. There were 17 men and 23 women with a mean age at surgery of 71.9 years (range 36–96). The mean follow up was 40 months (range 24–66). A porus tantulum modular multi hole uncemented cup was used in all cases. At time of assessment 6 patients had died, 2 patients developed dementia and another 2 patients were not contactable. All 10 patients had no significant clinical or radiological concerns at their last orthopaedic review. The remaining 29 alive patients (33 hips) were available for clinical evaluation. Harris hip score of these 33 hips showed, 24 excellent or good, 7 fair and 2 poor. Radiological results: All 39 patient’s (43 hips) radiographs were reviewed. The acetabular defect was quantified according to Paprosky.
Classification taking into account the intra operative findings and pre operative imaging. The horizontal (x-axis), vertical (y-axis) distance from the ipsilateral tear drop and abduction angle were measured in both the pre-operative and post-operative radiographs. According to Paprosky’s classification there were two 2A, ten 2B, six 2C, fourteen 3A and eleven 3B defects. All 43 hips showed good osseous integration. No loosening was noticed in our series. No significant improvement was noticed in the abduction angle and x-axis but significant improvement was noticed in the y-axis indicating more anatomical positioning of the cup within the acetabulum.
One deep infection. 2 of the 5 dislocations were recurrent and successfully managed with a constrained liner. We recommend the Porus tantulum uncemented cup as a very useful implant in often very difficult situation. The mechanical properties of the trabecular metal certainly helps to positively encourages osseous integration providing a sound biological fixation and the high co-efficient of friction helps to implant these cup with as little as 30% host bone contact.
Correspondence should be addressed to: Associate Professor N. Susan Stott, Orthopaedic Department, Starship Children’s Hospital, Private Bag 92024, Auckland, New Zealand.
