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For revision hip replacements, the implants were designed using our design strategies ofgraduate approach to different revision situation based on Paprosky’s classification of femoralbone defect. The implants were HA coated; some of them had distal cutting flutes. A total of158 patients (97 males and 61 females) who had operation between 1991 and 1998 werefollowed up, among them 138 cases were due to aseptic loosening, 6 cases were periprostheticfractures and 14 cases were infection. The average age was 63.1 years (range 34.6 – 85.9 years).The minimum follow up was 10 years (range 10 – 12 years). The mean Harris Hip Score wasimproved from 44.2 to 89.3, mean Oxford Hip Score was improved from 41.1 to 18.2 and themean WOMAC hip score was improved from 52.4 to 12.3 respectively. 6 cases required furtherrevision surgery, among them 3 were due to aseptic implant loosening, the overall survivorshipat ten years was 97%.The CAD-CAM hip stems are able to provide optimal implant fixation and restore hip functionfor every patient regardless their original femoral shape, bone condition and biomechanics ofthe hip. The excellent medium to long term clinical results justifies the use of CAD-CAMcustom hip stems.Friday, October 8, 2010, 15:20-16:00Session B14: Hip ResurfacingWear Simulator Studies of a Deflection Compensating Hip Joint*Azad Hussain - Smith & Nephew Orthopaedics Ltd - Leamington Spa, UK*Email: azad.hussain@smith-nephew.comWear simulator studies of a Deflection Compensating hip joint*Amir Kamali; *Joseph Pamu; **Jasper T Daniel; *Azad Hussain; *Chenxi Li*Implant Development Centre, Smith & Nephew Orthopaedics Ltd, Warwick, UK**University of Cambridge, Cambridge, UKImplant Development Centre (IDC), Smith & Nephew Orthopaedics, Aurora House, Spa Park,Harrison Way, Leamington Spa, CV31 3HL, U.K.IntroductionIn vitro studies have shown that low clearance metal-on-metal hip joints have the potential ofreducing wear during the running-in phase [1]. However, cementless acetabular cup relies onpress fitting into the acetabulum, which can generate non-uniform compressive stresses andnon-uniform in vivo cup deformation [2, 3]. This could then lead to equatorial contact, resultingin higher wear and friction for a MoM bearing with low clearance. To benefit from low weargenerated by low clearance and at the same time to avoid the potential of head seizure and highfrictional torque caused by cup deformation, a deflection compensation acetabular cup(DefCom) has been developed based on the Birmingham Hip Resurfacing (BHR) device. Thearticulating sphere of the DefCom cup provides a low clearance bearing area, whilst the non-file:///E|/ISTA2010-Abstracts.htm[12/7/2011 3:15:47 PM]