Ground Reaction Force Calcaneal Offset: A new measurement of hindfoot alignment

• Published in: Foot and ankle surgery Vol. 18; no. 1; pp. 9 - 14
• Main Authors: Lintz, Francois, Barton, Tristan, Millet, Mark, Harries, William J., Hepple, Stephen, Winson, Ian G.
• Format: Journal Article
• Language: English
• Published: France Elsevier Ltd 01.03.2012
• Subjects: Ankle biomechanics; Biomechanical Phenomena; Calcaneal offset; Calcaneus - diagnostic imaging; Calcaneus - physiopathology; Calcaneus - surgery; Computer assisted surgery; Female; Forefoot, Human - diagnostic imaging; Forefoot, Human - physiopathology; Forefoot, Human - surgery; Ground reaction force; Hindfoot alignment; Humans; Imaging, Three-Dimensional; Male; Middle Aged; Orthopedic Procedures - methods; Orthopedics; Radiographic Image Enhancement - methods; Range of Motion, Articular; Surgery, Computer-Assisted - methods; Surgical planning; Treatment Outcome; Weight-Bearing - physiology; Hindfoot alignment; Calcaneal offset; Computer assisted surgery; Surgical planning; Ankle biomechanics; Ground reaction force
• ISSN: 1268-7731; 1460-9584; 1460-9584
• DOI: 10.1016/j.fas.2011.01.003

The tibio-calcaneal angle (TCA) does not measure individual forefoot contributions to the overall foot balance. Using standard radiographs we calculated the ideal hindfoot alignment based on ground reaction force (GRF), independently from the tibial axis. Thirty-six patients (40ft.) were included. Mean age was 56. Weight bearing radiographs were taken. Calcaneal offsets were measured using tibio-calcaneal angles and GRF algorithms. Measurements were compared using the Bland–Altman method. Both methods agreed (p>0.05) but individual discrepancies were found. Mean measured offsets were −11.5mm (SD: 10.2) using TCA and −8mm (SD: 9.3) using GRF. Mean bias between the methods was −0.88mm. The GRF algorithm successfully measured hindfoot alignment. The absence of a previous gold standard and radiographic variability are a limit. The TCA underestimated calcaneal offset. Discrepancies showed that forefoot position data provided increased accuracy. This could be of particular relevance for surgical planning.