Comparative Mechanical Axis Deviation after TKA between Conventional and CAS Procedure
Chumroonkiet Leelasestaporn MD*
Affiliation : * Department of Orthopaedic Surgery, Bhumibol Adulyadej Hospital, Bangkok, Thailand
Objective : The purpose of the present study was to report the results of radiographic comparisons made
between CAS-TKA and conventional TKA.
Material and Method: The authors retrospectively compared 102 knee radiographs from conventional TKA
to 84 knees from CAS-TKA.
Results : The mean mechanical axis deviation was 2.77° for conventional TKA and 1.80° for CAS-TKA (p =
0.0002). For conventional TKA 42.2% of the results were considered to be outliers versus only 14.3% outlier
frequency among the CAS-TKA procedures (p < 0.0001). Only 54.4% of scanograms were proper for the
presented analysis due to improper anterior-posterior positioning. Implementation of a corrective standing
block eliminated this issue.
Conclusion : CAS-TKA significantly reduces both margins of error in knee alignment and frequency of outlier
compared with conventional TKA. Further investigation to compare long-term results of CAS-TKA with
conventional TKA is recommended.
Keywords : Computer assisted surgery, Total knee arthroplasty, Total knee replacement
