Fig. 2

Dorsal oblique computed tomography (CT) slices of the distal third metacarpal bone (MC3) and corresponding three-dimensional (3D) finite element (FE)–predicted articular cartilage (AC) pressure distributions. (A–C) Dorsal oblique CT slices of distal MC3 illustrating three subchondral bone (SCB) conditions: bilateral sclerosis (BS), a lateral parasagittal groove lesion with surrounding sclerosis (LGL, black arrow), and bilateral condylar lesions (BCL, black arrows). Dashed rectangles denote the ROI used for stress and strain analyses: a 50 mm mediolateral width centred at the apex of the PSG, i.e. SR, a 20 mm depth of superficial SCB from the joint surface proximally, and a 1 mm depth in the dorsopalmar direction (normal to the view). (D–F) 3D FE-predicted AC pressure (MPa) distributions generated by the proximal sesamoid bones (PSBs) over the MC3–PSB interface. The solid black lines in D–F indicate the precise dorsal oblique slice locations from which the CT images in A–C were obtained, showing how the internal SCB morphology corresponds to the predicted surface pressure distribution. Numbers 1–5 in A and D denote anatomical landmarks described in the text and also shown in (Fig. 1H): (1) lateral condyle (LC), (2) lateral PSB groove (LPSG), (3) sagittal ridge (SR), (4) medial PSB groove (MPSG), and (5) medial condyle (MC). (G) Sagittal view illustrating the distopalmar viewing direction (black arrow) in D–F and the dorsal oblique slice location. The colour bar indicates pressure magnitude (MPa).