PSI kinematic versus non-PSI mechanical alignment in total knee arthroplasty: a prospective, randomized study.
OBJECTIVE
Kinematic alignment in TKA is supposed to restore function by aligning the components to the premorbid flexion-extension axis instead of altering the joint line and natural kinematic axes of the knee. The purpose of this study was to compare mechanically aligned TKA to kinematic alignment.


METHODS
In this study, 200 patients underwent TKA and were randomly assigned to 2 groups: 100 TKAs were performed using kinematic alignment with custom-made cutting guides in order to complete cruciate-retaining TKA; the other 100 patients underwent TKA that was manually performed using mechanical alignment. The WOMAC and combined Knee Society Score (KSS), as well as radiological alignment, were determined as outcome parameters at the 12-month endpoint.


RESULTS
WOMAC and KSS significantly improved in both groups. There was a significant difference in both scores between groups in favour of kinematic alignment. Although the kinematic alignment group demonstrated significantly better overall results, more outliers with poor outcomes were also seen in this group. A correlation between post-operative alignment deviation from the initial plan and poor outcomes was also noted. The most important finding of this study is that applying kinematic alignment in TKA achieves comparable results to mechanical alignment in TKA. This study also shows that restoring the premorbid flexion-extension axis of the knee joint leads to better overall functional results.


CONCLUSIONS
Kinematic alignment is a favourable technique for TKA.


CONCLUSIONS
The kinematic alignment idea might be a considerable alternative to mechanical alignment in the future.


METHODS
II.
Department of Orthopedic Surgery, Hannover Medical School, Anna-v.Borries-Str.1-7, 30625, Hannover, Germany.
Tilman
T
Calliess
Department of Orthopedic Surgery, Hannover Medical School, Anna-v.Borries-Str.1-7, 30625, Hannover, Germany.
Kamil
K
Bauer
Department of Orthopedic Surgery, Hannover Medical School, Anna-v.Borries-Str.1-7, 30625, Hannover, Germany.
Christina
C
Stukenborg-Colsman
Department of Orthopedic Surgery, Hannover Medical School, Anna-v.Borries-Str.1-7, 30625, Hannover, Germany.
Henning
H
Windhagen
Department of Orthopedic Surgery, Hannover Medical School, Anna-v.Borries-Str.1-7, 30625, Hannover, Germany.
Stefan
S
Budde
Department of Orthopedic Surgery, Hannover Medical School, Anna-v.Borries-Str.1-7, 30625, Hannover, Germany. Max@ettinger.info.
Max
M
Ettinger
D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D001696:Biomechanical Phenomena; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000502:physiology / Q000601:surgery; D008297:Male; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery; D011446:Prospective Studies; D011859:Radiography
Kinematic alignment; PSI; Shape match; TKA; TKR; Total knee arthroplasty; Total knee replacement