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Comparing Postoperative Mechanical Axis In Total Knee Arthroplasty: Computer Navigation Vs Conventional System


Presenting Author - JIGAR CHHAPAN
Restoration of the mechanical axis (within 3 degree from ideal position) post total knee arthroplasty TKA is of paramount importance so as to allow optimum load sharing and prevent eccentric loading through the prosthesis which may lead to loosening, instability and early implant failure. Computer navigation is recognized as a valuable tool in restoring the mechanical axis post TKA and thereby increasing long-term survival and function of the prosthesis. An observational study was conducted retrospectively to compare post TKA mechanical axis between two groups. Out of 144 primary osteoarthritic knees, 70 knees were in group A operated by computer assisted navigation system (CAS) and 74 knees were in group B operated by conventional intramedulary femoral jig and extramedullary tibial jig. Postoperative long standing radiograph of the patients were used to assess the mechanical axis. 91.4% knees of CAS TKA, and 62.2% knees of conventional TKA achieved ideal mechanical axis. There is significant difference in both groups with chi square test. (p0.05) Overall result of CAS TKA is superior to conventional TKA. The latter requires measures to calculate valgus correction angle and modifying intramedullary guides, to achieve neutral mechanical axis especially in Indian population with abnormal lateral bowing of femur.