Related Experiment Video
Updated: Jun 29, 2026
In Vivo Quantification of Hip Arthrokinematics during Dynamic Weight-bearing Activities using Dual Fluoroscopy
Published on: July 2, 2021
Comparison between arithmetic, osteoarthritic and prosthetic HKA: a cohort of computer assisted unrestricted
Alvise Saracco1, Loic Ville2, Charles Rivière2
1Hip and Knee Replacement Unit, IRCCS San Raffaele Hospital, Via Olgettina 60, 20128 Milano, Italy; B.A.R.I. (Bordeaux Arthroplasty Research Institute), 6 Rue Georges Nègrevergne, 33700 Mérignac, France.
Introduction:
Kinematic alignment (KA) in total knee arthroplasty (TKA) aims to restore native knee anatomy and limb alignment. Accurate estimation of constitutional alignment is therefore essential. This study evaluated whether different Computer-Assisted Surgery (CAS)-derived hip-knee-ankle (HKA) measurements predict prosthetic alignment (pHKA).
Methods:
A total of 206 consecutive patients undergoing unrestricted KA-TKA were included. Osteoarthritic HKA (oaHKA), stressed osteoarthritic HKA (s-oaHKA), and prosthetic HKA (pHKA) were measured intra-operatively using CAS. Arithmetic HKA (aHKA) was calculated as MPTA-LDFA.
Results:
Mean pHKA was 0.52° varus (SD 2.56°). Strong correlations were found between pHKA and both s-oaHKA (r = 0.70) and aHKA (r = 0.76), whereas correlation with oaHKA was negligible (r = 0.06). The mean difference between pHKA and aHKA was 1.13°, compared to 1.7° for s-oaHKA. Only 2% of knees showed a difference ≥5° between aHKA and pHKA, compared to 8.2% for s-oaHKA.
Conclusion:
CAS-derived aHKA is a reliable predictor of prosthetic alignment and outperforms stress testing. Unrestricted KA-TKA resulted in extreme alignment (>5°) in only a small proportion of cases (4%).
Level Of Evidence:
IV; retrospective observational study.
