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.

Purpose Recent studies have emphasized the importance of anatomical ACL reconstruction to restore normal knee kinematics and stability. Aim of this study is to evaluate and compare the ability of the anteromedial (AM) and transtibial (TT) techniques for ACL reconstruction to achieve anatomical placement of the femoral and tibial tunnel within the native ACL footprint and to determine forces within the graft during functional motion. As the AM technique is nowadays the technique of choice, the hypothesis is that there are significant differences in tunnel features, reaction forces and/or moments within the graft when compared to the TT technique. Methods Twenty ACL‐deficient patients were allocated to reconstruction surgery with one of both techniques. Postoperatively, all patients underwent a computed tomography scan (CT) allowing 3D reconstruction to analyze tunnel geometry and tunnel placement within the native ACL footprint. A patient‐specific finite element analysis (FEA) was conducted to determine reaction forces and moments within the graft during antero‐posterior translation and pivot‐shift motion. Results With significantly shorter femoral tunnels (p < 0.001) and a smaller inter‐tunnel angle (p < 0.001), the AM technique places tunnels with less variance, close to the anatomical centre of the ACL footprints when compared to the TT technique. Using the latter, tibial tunnels were more medialised (p = 0.007) with a higher position of the femoral tunnels (p = 0.02). FEA showed the occurrence of higher, but non‐significant, reaction forces in the graft, especially on the femoral side and lower, however, statistically not significant, reaction moments using the AM technique. Conclusion This study indicates important, technique‐dependent differences in tunnel features with changes in reaction forces and moments within the graft. Level of evidence II.

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