Correlation between component alignment and short-term clinical outcomes after total knee arthroplasty

Abstract

ObjectiveThis study aimed to investigate the correlation between component alignment and short-term clinical outcomes after total knee arthroplasty (TKA).Methods50 TKA patients from a regional hospital were enrolled in the study. The following component alignments were measured from radiological data acquired within 1 week after surgery: hip-knee-ankle angle (HKA), medial distal femoral angle (MDFA), medial proximal tibial angle (MPTA), femoral flexion-extension angle (FEA), tibial slope angle (TSA), femoral rotational angle (FRA) and tibial rotational angle (TRA). The Hospital for Special Surgery (HSS) knee scoring system was used to assess clinical outcomes after 1 year, with patients being divided into three groups (excellent, good and not good) according to the HSS scores. Difference analysis and linear correlation analysis were used for the statistical analysis.ResultsThe results showed significant differences in MDFA (p = 0.050) and FEA (p = 0.001) among the three patient groups. It was also found that the total HSS had only a moderate correlation with FEA (r = 0.572, p < 0.001), but FEA had a positive linear correlation with pain scores (r = 0.347, p = 0.013), function scores (r = 0.535, p = 0.000), ROM scores (r = 0.368, p = 0.009), muscle scores (r = 0.354, p = 0.012) and stability scores (r = 0.312, p = 0.028). A larger MDFA was associated with lower FE deformity scores (r = −0.289, p = 0.042) and the TSA had a positive influence on the ROM (r = 0.436, p = 0.002). Also, changes in FRA produced a consequent change in the FE deformity score (r = 0.312, p = 0.027), and the muscle strength scores increased as TRA increased (r = 0.402, p = 0.004).ConclusionThe results show that the FEA plays a significant role in clinical outcomes after TKA. Surgical techniques and tools may need to be improved to accurately adjust the FEA to improve joint functionality and patient satisfaction.

Mechanical alignment tolerance of a cruciate-retaining knee prosthesis under gait loading—A finite element analysis

“…On the sagittal plane, extension malalignment of the femoral component has more of a negative impact on the clinical outcome than flexion malalignment. It has been demonstrated as one of the risk factors leading to failure after TKA ( Luan et al, 2022 ). In this study, internal malrotation and excessive external malrotation on the transverse plane caused higher stress and contact pressure on the tibial liner than the prosthesis with a neutral alignment.…”

“…The smaller contact area resulted in higher contact pressure and stress. Tibial internal rotation and excessive external rotation have been implicated in increasing the risk of failure of knee prostheses, and it is suggested to avoid such alignments during TKA procedures ( Kim et al, 2014 ; Luan et al, 2022 ).…”

“…However, nearly 20% of patients report dissatisfaction with the postoperative outcome because of pain and restricted function ( Bourne et al, 2010 ). Malalignment of the components is presented as one of the primary factors affecting postoperative outcomes and can lead to revision ( Thiele et al, 2015 ; Luan et al, 2022 ). Good alignment after TKA leads to faster rehabilitation and better joint functionality ( Longstaff et al, 2009 ; Abdel et al, 2018 ).…”

“…Surgeons consider it acceptable when the alignment error is within ±3°; otherwise, it is regarded as an outlier ( Abdel et al, 2014 ). Over 16% of component alignments have been reported as outliers in TKA procedures performed using conventional instrumentation ( Luan et al, 2022 ). Computer navigation systems, personal-specific instrumentation (PSI), and robotic surgeries have recently been introduced to improve alignment accuracy and reduce outliers.…”

Comparison of navigation systems for total knee arthroplasty: A systematic review and meta-analysis

“…Conventional instrumentation (CONI) is the most widely used apparatus for implanting knee prostheses and uses an intramedullary guide for femoral bone resection and extramedullary tibial bone resection. However, it is difficult to maintain accurate component alignment using this method, with studies showing that about 40% of the coronal and sagittal alignments errors were more than 3 degree which was regarded as the outliers of TKA procedures, and there are more outliers for the femoral component than the tibial component ( 13 ). Computer navigation (CN) systems using optical positioning have been developed to improve the accuracy of component alignment during TKA, with results showing fewer outliers and better long-term clinical scores than the CONI system ( 14 , 15 ).…”