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Thursday, October 7, 2010, 14:00-14:40Session A5: Hip MechanicsRestoration of Vertical and Horizontal Offset Using Dual Offset Stem inKorean*Yoon Je Cho - Kyung Hee University - Seoul, KoreaSang Joon Kwak - Kyung Hee University - Seoul, Republic of KoreaYoung Soo Chun - - ,Kee Hyung Rhyu - Center for Joint Disease, Kyung Hee University East-West Neo MedicalCenter - Seoul, KoreaDong Chul Nam - Kyung Hee University - Seoul, KoreaMyung Chul Yoo - Kyung Hee University - Seoul, Korea*Email: yjcho@khmc.or.krPurpose: The ultimate goal in total hip arthroplasty is not only to relieve the pain but also torestore original hip joint biomechanics. The average femoral neck-shaft angle(FNSA) in Koreantend to have more varus pattern. Since most of conventional femoral stems have relatively high,single, fixed neck shaft angle, it’s not easy to restore vertical and horizontal offset exactlyespecially in Korean people. This study demonstrates the advantages of dual offset(especiallyhigh-offset) stem for restoring original biomechanics of hip joint during the total hiparthroplasty in Korean.Materials and Methods: 180 hips of 155 patients who underwent total hip arthroplasty usingone of the standard(132°) or extended(127°) offset Accolade cementless stems were evaluatedretrospectively. Offset of stem was chosen according to the patient’s own FNSA in preoperativetemplating. In a morphometric study, neck-shaft angle of proximal femur, vertical offset andhorizontal offset, abductor moment arm were measured on preoperative and postoperative bothhip AP radiographs and the differences and correlation of each parameters, between operatedhip and original non-operated hip which had no deformity (preoperative ipsilateral orpostoperative contralateral hip), were analyzed.Results: The standard stems were used in 34 hips and extended offset stems were used in 146hips. The FNSA of non-operated hip was an average of 129.8°(127.2° 135.8°) in standardgroup and mean 125.4°(122.7° 129.9°) in extended offset group. The FNSA of operated hipwas an average of 131.6° and 127.1° in each group. In the statistical analysis, there was nosignificant difference of mean horizontal and abductor moment arm between operated hip andnon-operated hip in both groups and the restoration of horizontal offset and abductor momentarm showed(p=0.217, p=0.093) significant positive correlation(R=0.870, R=0.851) to theoriginal value. However, vertical offset was increased an average of 1.4mm in operated hip andthere was statistical significance. Restoration of vertical offset showed positive correlation tooriginal value (R=0.845).Conclusion: Dual- or multi-offset stem, especially extended offset stem can provide easyrestoration of hip biomechanics and soft tissue tension without significant alteration of leglength especially in Korean with more varus femoral neck compared to Caucacian. Preciseradiographic measurements of original hip and application of proper-offset stem should betaken in order to restore ideal hip biomechanics successfully and easily. A use of a proper offsetstem can afford to enhance joint stability and implant longevity by improving soft-tissuetension and reducing resultant force, and it will guarantee a successful results after total hiparthroplasty in the aspect of function and longevity.Keywords : Total hip arthroplasty, Hip biomechanics, Dual offset, Accolade, Koreanfile:///E|/ISTA2010-Abstracts.htm[12/7/2011 3:15:47 PM]