Objective: To establish a high-resolution US technique that enables a systematic morphometric examination of the three components that form the distal biceps brachii tendinous complex; the internal bicipital aponeurosis, the distal biceps brachii tendon and the external bicipital aponeurosis (also known as lacertus fibrosus).
Materials and methods: Fifty cryopreserved cadaver body donor elbows were dissected to obtain morphometric reference values and to establish reliable landmarks for the US examination. Then, a systematic US technique was designed and validated by a one-to-one US/dissection analysis of 11 cryopreserved cadaver body donor elbows. Finally, the systematic US technique was carried out in 44 healthy volunteers and morphometric parameters were compared to those obtained in the first part of the study.
Results: Mean dissection reference values: internal bicipital aponeurosis width 39.61 mm (10.02 SD) and thickness 0.75 mm (0.24 SD), distal biceps brachii tendon width 8.38 mm (1.87 SD) and thickness 2.73 mm (0.69 SD), external bicipital aponeurosis width 11.17 mm (5.84 SD) and thickness 0.85 mm (0.28 SD). One-to-one US/dissection correlation was overall good (intraclass correlation coefficient 0.876, p < 0.0001). When comparing volunteer US/dissection measurements, significant differences were encountered in all measures except for internal bicipital aponeurosis width. However, the overall magnitude of such significant differences was < 0.7 mm.
Conclusions: Using the systematics hereby proposed, high-resolution US is reliable for the morphometric assessment of the distal biceps brachii tendinous complex. The external bicipital aponeurosis is morphometrically the most variable structure.
Keywords: Distal biceps brachii tendon; External bicipital aponeurosis; Internal bicipital aponeurosis; Lacertus fibrosus; Ultrasound imaging.