Authors: Takeshi Shoji Takuma Yamasaki Soutarou Izumi Susumu Hachisuka Mitsuo Ochi
Publish Date: 2015/07/30
Volume: 40, Issue: 2, Pages: 245-253
Abstract
Using the computed tomography data of 101 patients who underwent THA threedimensional dynamic motion analysis was performed using a modular implant Kinectiv® stem that enabled adjustment of offset and leg length independently We defined offset as horizontal offset HO and leg length as vertical offset VO and measured the ROMCI and ROMBI in flexion Flex internal rotation IntR and external rotation ExtR with the configuration of each horizontal/vertical offsetWe found that HO lengthening increased the ROMCI and ROMBI in Flex and IntR by delaying bony impingement although excessive lengthening had minimal effect On the contrary VO lengthening decreased the ROMCI and ROMBI in Flex and ROMCI in IntR As for ExtR VO lengthening had positive effects on the ROMCI and ROMBI whereas lengthening of HO had negative effects on the ROMCI and ROMBIWe demonstrated that the appropriate long offset with a low shaft angle increased the ROM in Flex and IntR and a high neck shaft angle increased the ROM in ExtR We should use implants properly in accordance with the types of impingement for avoiding dislocations in THA
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