Description
Objectives: Total knee arthroplasty (TKA) is a cost-effective procedure widely used for severe knee osteoarthritis. Lower limb alignment & bony morphology of knee is not only related with knee OA incidence and progression but also surgical consideration for successful total knee arthroplasty. Several authors reported considerable variations in alignment and bony morphology between ethnicities. These variations seemed to change over time, even within patients of the same race. Asians (Korean) is more frequently femoral lateral bowing, varus condylar orientation and proximal tibial vara. These variations suggest that the goals of limb alignment and design of knee prostheses should also differ between races. Additionally, we believe that lower limb alignment & bony morphology of the knee seems to change over time in Korean patients.
The purpose of this study is to evaluate differences in the lower extremity alignment and bony morphology of total knee arthroplasty patients in Korea between 2004 – 2006 and 2020 – 2021 and to compare the correlation between radiographic variables in these patients.
Methods: We retrospectively reviewed 729 knees of 578 patients and 1122 knees of 906 patients who underwent TKA for osteoarthritis between 2004 and 2006 and between 2020 and 2021, respectively. A single observer reviewed the preoperative full-limb patient radiographs and measured radiographic variables such as the tibiofemoral angle (TFA), the lateral distal femoral angle (LDFA), the medial proximal tibial angle (MPTA), and the femoral bowing angle (FBA). We compared these patient variables between two time periods : 2004 and 2006 (first-half group) and 2020 and 2021 (second-half group).
Results: We found significant differences in lower limb alignment and bony morphology between the two groups.
Recent TKA patients showed less varus limb alignment, less varus condylar orientation, less tibia vara, and less femoral lateral bowing. (Mean mTFA (-11.55 vs. -8.70, p= .00), LDFA (89.69 vs. 88.76, p=.00), MPTA (82,80 vs 84.73, p=.00) and FBA (4.97 vs. 1.78, p=.00)). In both groups, mTFA was positively correlated with MPTA, while TFA was negatively correlated with LDFA and FBA. However, these correlations were weaker in recent TKA patients.
Conclusions: The study demonstrates that lower extremity alignment was more neutral, and bony deformity around the knee was less severe in the patients underwent TKA between 2020-2021 than those between 2004-2005. The causes associated with these changes are not clear; rapidly westernized lifestyle and improved management of osteoporosis may have reduced acquired bony deformity that could lead to varus deformity, and consequently produced this change.
Potential changes in lower limb alignment & bony morphology of the knee over time should be considered when establishing a strategy for alignment or designing TKA system.
