Abstract
Introduction: We report our experience with the ZMR Hip System (Zimmer Inc.). The system accommodates a number of femoral fixation philosophies including spline, porous and taper stem options. The tapered stem is designed to achieve a distal wedge fit and also allow bone on-growth via the corundumized titanium alloy surface. The modular mid-stem junction allows a selection of body designs to be selected providing significant intra-operative flexibility and version adjustment.
Method: This study considers 64 cases performed in 63 patients with a mean age at the time of surgery of 70 years (range 55–89) utilising the taper stem design. The indication for revision surgery was aseptic loosening in 33 patients (Paprosky types II – 12, IIIA-10, IIIB-11) 22 peri-prosthetic fractures (Vancouver types B2-15, B3-7), 8 for infection and 4 patients with instability.
Results: The cohort had a minimum three-year follow-up with a mean of 50 months (range 36–72) and clinical assessment included Oxford score and thigh pain assessment. Engh’s criteria was utilised in the radiological evaluation when considering femoral component fixation. Femoral stem subsidence and femoral bone stock were also appraised on serial follow-up radiographs.
Discussion: The survival rate at follow-up with stem revision being the end point was 100%. When re-operation for any reason and radiological loosing are considered as the end point the survival rate was 95%.
Conclusion: We conclude excellent medium term results with the use of a cementless modular taper stem in challenging femoral revision surgery.
Correspondence should be addressed to The Secretary, BHS, c/o BOA, The Royal College of Surgeons, 35–43 Lincoln’s Inn Fields, London WC2A 3PE.
