J Orthopaed Traumatol (2008) 9:57–62 Fig. 2 a AP pre-revision radiograph. b Post operative radiograph of revision right THA using Zweymuller stem. c 8-year follow-up radiographs. d 15-year follow-up radiograph, with some evidence of stress shielding of the greater trochanter Table 3 Clinical data Follow-up group Harris hip score (pre) Harris hip score (post) Anterior thigh pain Patients needing pre-op pain medication Patients needing pain medication at last F/U Medium term (n = 16) 39 (32–45) 87 (81–92) 3 11 4 Long term (n = 8) 48 (39–57) 96 (88–103) 0 4 0 P Value 0.091 0.056 0.19 0.37 0.12 Harris hip scores reported as mean (95% CI) combinations of proximal and/or distal ﬁt. Most techniques require rigid ﬁt in the femoral diaphysis. Paprosky et al. [4] reported their experience in 170 extensively porous-coated stems. These THAs were followed for a mean of 13 years. Overall stem survival at 15 years was 95%. Radiographic evaluation demonstrated bony-stable stem ﬁxation in 82%, and ﬁbrous-stable ﬁxation in 14% of the hips. Six femoral stems were re-revised due to loosening. Similar clinical 61 P value 0.47 0.77 0.31 Table 4 Radiographic data Follow-up group Bony ingrowth Subsidence Distal cortical hypertrophy Proximal stress shielding Medium term (n = 16) 100% (16/16) 6% (1/16) 44% (7/16) 19% (3/16) Long term (n = 8) 100% (8/8) 0% (0/8) 38% (3/8) 38% (3/8) efﬁcacy and ﬁxation durability have also been reported with modular stem designs. Christie et al. [5] reported on 129 revisions using the S-ROM stem (DePuy a Johnson & Johnson Company. Warsaw, IN). The mean follow-up was 6.2 years. Overall stem survival at 10 years was 98%. Radiographic evaluation demonstrated bony-stable ﬁxation of the stems in 92%. Clinical efﬁcacy was reﬂected in an increase of the Harris hip score from 47 (preoperative) to 87 (ﬁnal follow-up). One femoral component underwent re-revision for mechanical loosening. Kwong et al. [6] reported on the short-term results of using the Link mod- ular tapered stem (Waldemar Link GmbH & Co, Hamburg, Germany) in 143 revision THAs. The overall stem survival rate was 97% at 5 years. Moreover, the mean Harris hip score at ﬁnal follow-up was 92. A total of 4 femoral stems underwent re-revision, one for infection, one due to sur- gical error, and 2 due to mechanical component failure. The Zweymuller femoral stem is designed with a unique geometry, which provides several advantages when used in revision THAs. The rectangular cross-section and wedge- shaped tapered geometry allows for four-point ﬁxation along the four corners within the femoral canal. The ﬁxa- tion is not dependent upon ﬁlling of the diaphysis such as in the case of either cylindrical extensively-coated, or modular straight/tapered stem designs. It does require an intact metaphysic-diaphysis junction. Extensive femoral bone deﬁciencies such as Paprosky IIIa or IIIb [4] may be challenging, especially without longer length of this par- ticular stem design to gain ﬁxation in the upper diaphysis. There is the additional advantage of no required diaphyseal reaming in femoral canal preparation. This may avoid inadvertent distal perforations or fractures. Avoid- ance of reaming also in theory preserves greater femoral canal blood ﬂow to maximize bone healing potential around the stem. We found bony-stable ﬁxation in 100% of our stems. Fixation did not deteriorate between the med- ium-term (5+ years), and the longer-term (12 years) follow-up groups. Finally, we did not observe any signiﬁ- cant qualitative adverse bone remodeling as we compared sequential radiographs for each patient. Stress shielding has been widely reported with the use of extensively-coated stems with stable distal ﬁxation [14, 15, 16]. Care must be taken with preparation and insertion of this stem. Its wedge-shape geometry has the potential to result 123