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in good agreement with the literature data. Next, we introduced the data during the activitieswith deep knee flexion; double leg ascent [Fig.1 (a)] and single leg ascent [Fig.1 (b)] fromkneeling without using the upper limbs.The statistics of the maximum values on the single knee joint for all the subjects were; duringdouble leg ascent, F max = 4.6±0.6 (4.3--5.2) [BW: (force on the knee joint)/(body weight)] atknee flexion angle of b =140±8 (134--147)°, during double leg ascent, F max = 4.9±0.5 (4.0--5.6) [BW] at b = 62±33 (28--110)° for the dominant leg, and F max = 3.0±0.5 (22.2--3.8) [BW]at b = 138±6 (130--150)° for the supporting leg respectively. We found that the moment armlength, i.e., the location of muscle insertion significantly affected the results, while ascendingspeeds did not affect the results much. We may conclude that the single leg ascent should berecommended since F max did not become large while deep knee flexion. The values could beused for assessing the strength of our knee prosthesis from the risk analysis view point.FiguresSaturday, October 9, 2010, 7:45-8:50Session B16: Performance and Survivorship in Arthroplasty10-17 Years Survivorship of CAD-CAM Primary and Revision Hip Stems*Jia Hua - University College London - Stanmore, UKSarah Muirhead-Allwood - Royal National Orthopaedic Hospital Trust - Stanmore, UKAmir Sandiford - London Hip Unit - London, UKJohn Skinner - Royal National Orthopaedic Hospital Trust - Stanmore, UKPeter Walker - - New York, USA*Email: j.hua@ucl.ac.ukTotal hip replacements have shown great benefits to patients through relief of pain andrestoration of function. However, because of the extensive variation in the size and shape of thefemoral canal, especially for the situation encountered in the revision hip arthroplasty, standarduncemented hip systems with a limited number of sizes are unable to provide an accurate fit inevery case. This study showed clinical results of 112 primary total hip replacements and 158revision total hip replacements, using custom made CAD-CAM (Computer Aided Design-Computer Aided Manufactured) hip prostheses inserted between 1992 and 1998.For primary hip replacements, the implants were designed to produce proximal line-to-line fitwith the femoral bone and to provide optimal biomechanical environment of the hip. The stemwas HA coated, 53 males and 58 females were included. Mean age was 46.2 years (range24.6yrs - 62.2 yrs). The average duration of the follow up was 24 years (10 – 17 years). Themean Harris Hip Score (HHS) was improved from 42.4 to 90.3, mean Oxford Hip Score (OHS)was improved from 43.1 to 18.2 and the mean WOMAC hip score was improved from 57.0 to11.9. There was 1 revision due to failure of the acetabular components but there were nofailures of the femoral components. In the whole follow-up period, the survival of the femoralstem alone was 100%.file:///E|/ISTA2010-Abstracts.htm[12/7/2011 3:15:47 PM]