Length Changes in the Interosseous Membrane During Forearm Rotation: A 3-Dimensional Study In Vivo

Area of Science:

• Anatomy
• Biomechanics
• Orthopedics

Background:

• The interosseous membrane (IOM) is crucial for forearm stability.
• Its length changes during rotation are not fully understood.
• Specific bands within the IOM may have distinct roles.

Purpose of the Study:

• To investigate length changes in the distal oblique band (DOB), distal accessory band (DAB), and central band (proximal, middle, distal parts: CBP, CBM, CBD) of the IOM.
• To analyze these changes in vivo across various forearm rotation positions.

Main Methods:

• Computed tomography (CT) scans of 6 healthy volunteers' forearms.
• 3D models of radius, ulna, and IOM components were created.
• Ligament lengths were calculated from 3D models at five rotational positions.

Main Results:

• DAB and CBD lengthened significantly from maximum pronation to 45° pronation.
• DOB lengthened from 45° pronation to neutral and shortened from 45° supination to maximum supination.
• CBP length remained nearly constant throughout rotation.

Conclusions:

• The DOB is taut at neutral position, suggesting primary distal radioulnar joint stabilization.
• The central band, particularly CBP, is nearly isometric, acting as a key stabilizer during rotation.
• Findings guide clinical attention to DOB in injuries and CBP for IOM reconstruction.