[Relationship between midcarpal inclination angle and scaphoid kinematic].
OBJECTIVE
To investigate if there is a correlation between the so-called midcarpal inclination angle and the kinematic behavior of the scaphoid.


METHODS
The population studied was 60 patients with postero-anterior radiographs of the wrist in full radial and ulnar deviation. Each patient was assessed for the type of lunate by two independent observers. For each pair of radiographs the Midcarpal Inclination Angle and the Scaphoid Flexion Index (SFI) was determined.


RESULTS
Twenty-three cases were classified as lunate type I, 19 cases as type II. The average midcarpal inclination angle was 55.2° (SD±6.1) for wrists with a lunate type I and 63.8° (DE±6.3) for type II (p<0.0001). There was a significant linear relationship between the midcarpal inclination angle and the Scaphoid Flexion Index (p=0.02).


CONCLUSIONS
The wrists with a midcarpal inclination angle greater than 60° (type II lunate) had a scaphoid rotating according to a "columnar pattern", during radioulnar inclinations (predominant rotation along the sagittal plane), while the wrists with a lunate type I behave according to a "row pattern".
Institut Kaplan, Passeig de la Bonanova, n(o) 9, 2-2, 08022 Barcelone, Espagne. ludovicardouin@me.com
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Racca
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D000328:Adult; D001696:Biomechanical Phenomena; D002348:Carpal Bones / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D005260:Female; D006801:Humans; D008297:Male; D011859:Radiography; D021361:Scaphoid Bone / Q000000981:diagnostic imaging / Q000502:physiology*