Personalized alignment techniques better restore the native trochlear groove compared to systematic alignment techniques in total knee arthroplasty

PurposeThe purpose of this study was to assess whether kinematic alignment (KA) outperforms mechanical alignment (MA) in restoring patellar tracking to native patterns by using a clustering algorithm.MethodsTwenty cadavers (40 knees) were evaluated. For each cadaver, one knee was randomly assigned to KA and the other to MA. KA total knee arthroplasty (TKA) procedures were performed using a caliper‐verified technique, while MA TKA procedures utilized a measured resection technique. Subsequently, all specimens were mounted on a customized knee‐testing system, and patellar tracking was measured using a motion analysis system. All patellar tracking data were clustered using the density‐based spatial clustering of applications with noise algorithm. Differences in patellar tracking patterns and the restoration of native patellar tracking were compared between the two alignment strategies.ResultsPatellar tracking patterns following KA were considerably different from MA. Pre‐ and post‐TKA patellar tracking patterns following MA were grouped into separate clusters, whereas a substantial proportion of patellar tracking patterns following KA were grouped into the pre‐TKA dominant cluster. Compared to MA, a greater proportion of patellar tracking patterns following KA showed similar patterns to native knees (p < 0.05) and more patellar tracking patterns following KA paired with preoperative patterns (p < 0.01).ConclusionKA restored native patellar tracking patterns more closely compared to MA.Level of EvidenceLevel I, therapeutic study.

Kinematical alignment better restores native patellar tracking pattern than mechanical alignment

Kim,

Lim,

Kwak

et al. 2024

Restoration of the anterior compartment after robotic total knee arthroplasty significantly improves functional outcome and range of motion at 1 year

Kafelov,

Batailler,

Servien

et al. 2024

PurposeThis study aims to assess the functional outcomes based on restoring the anterior compartment after total knee arthroplasty (TKA).MethodsThis retrospective study included 96 primary TKAs performed between 2021 and 2022. Functional positioning principles were applied using an image‐based robotic‐assisted system. The mean age was 69.2 ± 7.9 years. Knee Society Score (KSS), Kujala score, Forgotten Joint Score (FJS) and knee flexion were collected preoperatively and at 1 year. The depth difference between native and prosthetic trochlea was measured to assess anterior compartment restoration at full extension, 30°, 70° and 90° flexion. The global anterior compartment restoration combined the anterior compartment restoration and the patellar thickness restoration.ResultsThe trochlear offset was mostly understuffed after TKA compared to the native anatomy, mainly for medial and lateral condyles at 30° and 70° of flexion. The global anterior compartment restoration was understuffed in full extension (−0.7 mm ± 2), at 30° (−4.4 mm ± 2) and 70° of flexion (−3.6 mm ± 2.5). At 90°, the global anterior compartment restoration was overstuffed (2.2 mm ± 1.8). Functional scores were not significantly influenced by the anterior compartment stuffing at 0° and 30° (n.s.). The anterior compartment overstuffing at 70° and 90° was associated with decreased KSS function score (p = 0.009) and flexion (p = 0.04).ConclusionModerate anterior understuffing was frequently observed after TKA performed with functional positioning and an image‐based robotic‐assisted system. This understuffing did not influence the functional outcomes. The overstuffing of the anterior compartment led to a reduction in KSS function score and flexion measurements at 1 year.Level of EvidenceLevel III, retrospective cohort study.

Kinematic alignment adequately restores trochlear anatomy, patellar kinematics and kinetics in total knee arthroplasty: A systematic review

Ollivier,

Luyckx,

Stragier

et al. 2024

PurposePatellofemoral pain, maltracking and instability remain common and challenging complications after total knee arthroplasty. Controversy exists regarding the effect of kinematic alignment on the patellofemoral joint, as it generally leads to more femoral component valgus and internal rotation compared to mechanical alignment. The aim of this systematic review is to thoroughly examine the influence of kinematic alignment on the third space.MethodsA systematic search of the Pubmed, Cochrane and Web of Science databases was performed to screen for relevant articles published before 7 April 2024. This led to the final inclusion of 42 articles: 2 cadaveric, 9 radiographic, 12 computer simulation and 19 clinical studies. The risk of bias was evaluated with the risk of bias in non‐randomised studies ‐ of interventions tool as the lowest level of evidence of the included clinical studies was IV. The effects of kinematic alignment on patellar kinematics and kinetics, trochlear anatomy reconstruction and patellofemoral complication rate were investigated.ResultsKinematic alignment closely restores native patellar kinematics and kinetics, better reproduces native trochlear anatomy than mechanical alignment and leads to a 0%–11.4% incidence of patellofemoral complications. A more valgus joint line of the distal femur can cause lateral trochlear undercoverage and a trochlear angle orientation medial to the quadriceps vector when applying kinematic alignment, both of which can be solved by using an adjusted design with a 20.5° valgus trochlea.ConclusionKinematic alignment appears to be a safe strategy for the patellofemoral joint in most knees, provided that certain precautions are taken to minimize the risk of complications.Level of EvidenceLevel IV clinical studies, in vitro research.