Cadaveric Study of Insertional Anatomy of Distal Biceps Tendon and its Relationship to the Dynamic Proximal Radioulnar Space.

ABSTRACT

PURPOSE: To quantify and assess the relationship between the insertional dimensions of the distal biceps tendon (DBT) and radioulnar space (RUS) in 3 rotational positions. We hypothesized that in all positions RUS would be adequate for the DBT and would remain adequate even after an incremental increase (1 to 3 mm) in tendon thickness. METHODS: Eleven fresh-frozen cadaveric elbows were dissected; DBT dimensions and bicipital tuberosity measurements were performed and insertional footprints were quantified using a distal biceps footprint index. The RUS was measured at 3 levels of the bicipital tuberosity and in 3 positions of forearm rotation. We performed statistical analysis to analyze differences in RUS (positional and inter-level). In addition, significant differences between DBT thickness (native and incremental) and RUS were analyzed to identify potential sites of radioulnar impingement. RESULTS: The DBT had a mean length of 92 mm; thickness ranged from 2.9 to 6.1 mm. Three variations in DBT insertional footprint were observed and quantified. The RUS linear distance reduced significantly from a supinated to a pronated position at each of 3 bicipital tuberosity levels; the reduction was statistically significant at the lower tuberosity level (45%). Pronation RUS distance was adequate for native DBT thickness and was significantly less when DBT thickness increased by 2 and 3 mm. CONCLUSIONS: Radioulnar space reduces significantly from the supinated to the pronated position and is most evident in the lower aspect of the tuberosity. In addition, the RUS in pronation is inadequate for incremental increases in DBT thickness. CLINICAL RELEVANCE Postoperative DBT impingement in the RUS may be prevented by avoiding techniques that increase the thickness of the tendon and by using a reattachment site at the proximal aspect of the tuberosity.