Abstract
BackgroundThe kinematic alignment (KA) technique in total knee arthroplasty (TKA) aims to restore the native alignment of pre-disease knee joint anatomy. Determining the individualized alignment targets is crucial for pre-operative planning, which can be set according to different original knee phenotypes. Five most common knee phenotypes have been categorized for KA-TKA alignment target setting in our previous study. The purpose of this study was to investigate the distribution of the five phenotypes in advanced OA knee patients and evaluate the clinical outcomes of this phenotype-oriented KA-TKA using the generic instrument, with particular emphasis on alignment strategy, surgical technique, survivorship, radiographic and functional outcomes.MethodsThe clinical data of 123 patients (88 women, 35 men) who had undergone 140 TKAs in our hospital were reviewed. All the TKAs were performed with alignment targets set according to the original phenotypes of the knee, with the KA method, using the generic total knee instrument. The patients’ demographics, preoperative and postoperative knee alignment angles, one-year postoperative range of motion (ROM), Oxford knee scores (OKS), Combined knee society score (CKSS) were collected and analyzed.ResultsThe 3 years survivorship was 99.3% for all cause of revision, and 100% with revision other than infection as the endpoint. The preoperative phenotypes of the knee were as follows: neutral alignment 20.1% (type 1: 3.6%, type 2: 16.5%), varus alignment 71.2% (type 3: 46.0%, type 4: 25.2%), and valgus alignment (type 5: 8.6%). Using our protocol, patients with different knee phenotypes could get similar great functional improvement though the postoperative alignment parameters were significantly different between the knee phenotypes (P < 0.05).ConclusionThe early outcomes of this phenotype-oriented KA-TKA using generic total knee instruments are promising. Setting individualized alignment target according to original knee phenotype is rational and practical. The residual varus alignment did not cause any aseptic loosening in the 3 years follow-up. Long-term survivorship and functional outcomes need to be evaluated in future studies.
Highlights
The kinematic alignment (KA) technique in total knee arthroplasty (TKA) aims to restore the native alignment of pre-disease knee joint anatomy
Though total knee arthroplasty is the definitive surgical treatment for advanced osteoarthritis of knee (OA knee), high dissatisfaction rates of up to 20% are still reported in uncomplicated TKA [1,2,3]
Significant improvement was observed in hip-knee-ankle angle (HKAA), knee alignment angle (KAA), tibial joint line obliquity angle (TJLA), medial proximal tibial angle (MPTA), Oxford knee scores (OKS), Combined knee society score (CKSS), and range of motion (ROM) after the operation
Summary
The kinematic alignment (KA) technique in total knee arthroplasty (TKA) aims to restore the native alignment of pre-disease knee joint anatomy. Though total knee arthroplasty is the definitive surgical treatment for advanced osteoarthritis of knee (OA knee), high dissatisfaction rates of up to 20% are still reported in uncomplicated TKA [1,2,3] This high dissatisfaction rate has raised the question as to whether the aim of bone resection should be to achieve ideal mechanical alignment that is appropriate for each patient. In contrast to the mechanical alignment (MA) method which aims to create a neutral alignment by cutting the tibia and femur perpendicular to the mechanical axis [4, 5], the kinematic alignment (KA) method aims to restore the pre-disease knee joint by resecting bone parallel to the pre-disease joint line of the femur and tibia [6]. Placing prosthesis in mal-aligned axis may compromise the long-term survival
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