J Korean Orthop Assoc.  2023 Apr;58(2):141-148. 10.4055/jkoa.2023.58.2.141 .

Influence of the Femoral Implant Alignment on the Clinical Outcomes One Year after Total Knee Arthroplasty

• Nam JH
• Choi JH
• Che SH
• Choi Wk

• KMID: 2541469
• DOI: http://doi.org/10.4055/jkoa.2023.58.2.141

Abstract

Purpose
The relationship between the improvement of knee society score (KSS) at postoperative one year after total knee arthroplasty (TKA) and the appropriate alignment of implants was investigated.
Materials and Methods
A retrospective study was conducted on 152 primary TKA cases from August 2015 to March 2020. The mechanical hip-knee-ankle (mHKA) angle, mechanical lateral-distal-femoral angle (mLDFA), femoral flexion angle (FFA), and mechanical medial-proximal-tibial angle (mMPTA) were measured to evaluate the alignment of the implants. 0°±3° was considered an appropriate mHKA angle and FFA, and 90°±3° was considered an appropriate mMPTA and mLDFA. The KSS, which consists of the knee score and function score, was measured on the day before surgery and one year after surgery to evaluate the improvement of knee function after TKA. Regression analysis was conducted to study the relationships between the proper alignment (mHKA, mMPTA, mLDFA, FFA) of the implant after TKA with patient factors (sex, age, body mass index, and preoperative varus deformity) and the improvement of knee function at oneyear post-TKA.
Results
In multiple regression analysis, obtaining an appropriate FFA showed a significantly higher Knee score improvement at one-year post-TKA. In addition, a significantly higher Knee score was obtained at one-year post-TKA when the age was younger and the degree of varus deformity was more severe. For recovery of the function score, obtaining an appropriate FFA showed a significantly better function score improvement. In addition, the function score was improved as the degree of preoperative varus deformity increased. Male showed a significantly better improvement in the function score than female at one-year post-TKA.
Conclusion
Ideal alignment of FFA had a significant relationship with the degree of KSS recovery one year after TKA. Better improvement in the KSS score was found when proper alignment of the FFA was achieved.

Keyword

alignment; knee society score; total knee arthroplasty