Comparison of Accuracy between Side-Cutting
Instruments and Front-Cutting Instruments in
Minimally Invasive Total Knee Arthroplasty
Piya Pinsornsak MD*,
Thos Harnroongroj MD**
Affiliation :
* Department of Orthopedic Surgery, Faculty of Medicine, Thammasat University, Pathum Thani, Thailand
** Department of Orthopaedic Surgery, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand
Background : The specialized instrument system used in minimally invasive surgery (MIS) has been developed for reducing
soft tissue trauma in total knee arthroplasty (TKA). Compared with front-cutting MIS instruments, side-cutting quadriceps
sparing MIS instruments have the advantage of creating a smaller incision and causing fewer traumas to the quadriceps
tendon. However, the accuracy of side-cutting instruments concerns surgeons in prosthesis malalignment.
Objective : To compare the accuracy of side-cutting quadriceps sparing instruments versus front-cutting instruments in
MIS-TKA.
Material and Method: In this prospective randomized controlled study, we compared the accuracy of side-cutting quadriceps
sparing instruments versus the front-cutting instruments used in MIS-TKA. Sixty knees were included in the study, with 30
knees in each group. All the operations were performed by single surgeon. Coronal alignment (tibiofemoral angle, lateral
distal femoral angle, and medial proximal tibial angle), and sagittal alignment (femoral component flexion and tibial
posterior slope) were measured and compared.
Results : Tibiofemoral angle, lateral distal femoral angle, and medial proximal tibial angle, all of which are considered in
the assessment of acceptable coronal radiographic alignment, were not different between groups (p = 0.353, 0.500, and
0.177, respectively). However, side-cutting quadriceps sparing instruments produced less acceptable sagittal radiographic
alignment, femoral component flexion (63% vs. 93%, p = 0.005), and tibial posterior slope (73% vs. 93%, p = 0.04).
Conclusion : Side-cutting quadriceps sparing MIS-TKA instruments had similar accuracy to front-cutting MIS-TKA
instruments for coronal alignment but is less accurate for sagittal alignment.
Keywords : Total knee arthroplasty, Minimally invasive surgery, Instruments, Accuracy, Osteoarthritis
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