Higher satisfaction after total knee arthroplasty using restricted inverse kinematic alignment compared to adjusted mechanical alignment

Abstract

Purpose Various alignment philosophies for total knee arthroplasty (TKA) have been described, all striving to achieve excellent long-term implant survival and good functional outcomes. In recent years, in search of higher functionality and patient satisfaction, a shift towards more tailored and patient-specific alignment is seen. The purpose of this study was to describe a restricted 'inverse kinematic alignment' (iKA) technique, and to compare clinical outcomes of patients that underwent robotic-assisted TKA performed by restricted iKA vs. adjusted mechanical alignment (aMA). Methods The authors reviewed the records of a consecutive series of patients that received robotic-assisted TKA with restricted iKA (n = 40) and with aMA (n = 40). Oxford Knee Score (OKS) and satisfaction on a visual analogue scale (VAS) were collected at a follow-up of 12 months. Clinical outcomes were assessed according to patient acceptable symptom state (PASS) thresholds, and uni-and multivariable linear regression analyses were performed to determine associations of OKS and satisfaction with six variables (age, sex, body mass index (BMI), preoperative hip-knee-ankle (HKA) angle, preoperative OKS, alignment technique). Results The restricted iKA and aMA techniques yielded comparable outcome scores (p = 0.069), with OKS, respectively, 44.6 ± 3.5 and 42.2 ± 6.3. VAS Satisfaction was better (p = 0.012) with restricted iKA (9.2 ± 0.8) compared to aMA (8.5 ± 1.3). The number of patients that achieved OKS and satisfaction PASS thresholds was significantly higher (p = 0.049 and p = 0.003, respectively) using restricted iKA (98% and 80%) compared to aMA (85% and 48%). Knees with preoperative varus deformity, achieved significantly (p = 0.025) better OKS using restricted iKA (45.4 ± 2.0) compared to aMA (41.4 ± 6.8). Multivariable analyses confirmed better OKS (β = 3.1; p = 0.007) and satisfaction (β = 0.73; p = 0.005) with restricted iKA. Conclusions The results of this study suggest that restricted iKA and aMA grant comparable clinical outcomes at 12-month follow-up, though a greater proportion of knees operated by restricted iKA achieved the PASS thresholds for OKS and satisfaction. Notably. in knees with preoperative varus deformity, restricted iKA yielded significantly better OKS and satisfaction than aMA. Level of evidence Level III, comparative study.

Short- to mid-term outcomes of computer navigation assisted total knee arthroplasty using adjusted mechanical alignment compared to mechanical alignment

“…In our study, we found similar tibial resection angle in the aMA and MA groups. However, the overall coronal limb alignment averaged 1.11° more varus/valgus and femoral component was placed in 2.29° more varus/valgus in the aMA group, which is consistent with the ndings of Winnock et al, who adjusted femoral component to preserve mild constitutional deformity with the aMA technique [28]. These ndings also match the stated concept of kinematic alignment technique to reverse the alignment of the pre-arthritis native knee [33].…”

“…In contrast, aMA technique is considered as an extension of the conventional MA technique in TKA, aiming to correct the coronal lower limb deformity within a maximum of 3° varus or valgus by tuned the position of femoral component, without performed soft tissue releases as much as possible. aMA-TKA was reported to provide good clinical outcomes for varus and valgus knees [28]. However, as far as we are aware, no comparable clinical study between aMA and MA technique in TKA has been previously performed, which is possibly due to the limited choices of alignment technique under conventional instruments.…”

New Technologies in Knee Arthroplasty: Current Concepts

“…Indeed, these systems allow for accuracy in implant positioning and limb alignment and can facilitate the alignment reflection. Some authors have even described an adaptation of the kinematic alignment with the robotic-assisted system [100,101].…”

Personalized alignment in total knee arthroplasty: current concepts

“…Winnock de Grave et al described this new concept and technique with a robotic-assisted system [ 34 ]. The tibial implant is positioned first with resection of equal amounts of bone lateral and medial on the tibia, after correcting for bone wear.…”

“…Only Winnock de Grave et al have reported the outcomes of the inverse KA. They found no significant difference in clinical results at 12 months between inverse KA and adjusted MA [ 34 ]. They reported a higher rate of satisfaction and significant improvement in postoperative OKS for restricted inverse KA, compared to adjusted MA.…”