The interosseous tuberosity of radius: a descriptive radiological and cadaveric anatomical study.

Purpose: The radius is described with a single tuberosity: the radial tuberosity. However, we hypothesize that there is a second tuberosity on the interosseous border of the radius: which we propose to call the interosseous tuberosity - Tuberositas interossea radii - (IT).

Methods: First, we analyzed all anteroposterior radiographs of the forearm (48 females, 54 males; 62 lefts and 40 rights) as well as CT scans (6 females, 7 males; 5 lefts and 8 rights) carried out during one year in our hospital. We evaluated the presence of IT, its length, thickness of the interosseous cortex at IT level, above and below compared with anterior, posterior and lateral bone cortices. In the second part of the study, we dissected cadaveric forearms to determine which ligaments and muscles were attaches on the IT.

Results: A total of 102 standard forearm radiographs and 13 CT-scans were analyzed. In all cases, an IT was present. The mean tuberosity length was 93.9 mm (+ / - 15.8), which corresponds to 37% (+ / - 5) of total radial length. IT corresponds to a significant thickening (7.6 mm than 4.2 mm and 4.3 mm below; p < 0.0001) of radial interosseous cortex. A total of 10 forearms were dissected. In all cases, we observed that IT served as an attachment for central band of interosseous membrane and for all extrinsic muscles of the thumb with the exception of the extensor pollicis longus.

Conclusion: Tuberositas interossea radii exists, corresponds to a cortex thickening and may play a role in the stability of the forearm and the function of the thumb.