ANATOMIC FACTORS ASSOCIATED WITH PARTIAL DISTAL BICEPS TENDON TEARS: A COMPARATIVE CONTROL STUDY

Abstract

A larger radial tuberosity, and therefore a smaller radioulnar space, may cause mechanical impingement of the DBT predisposing to tear. We sought to investigate anatomic factors associated with partial DBT tears by retrospectively reviewing 3-T MRI scans of elbows with partial DBT tears and a normal elbow comparison group3-T MRI scans of elbows with partial DBT tears and elbows with no known pathology were reviewed retrospectively by two independent observers. Basic demographic data were collected and measurements of radial tuberosity length, radial tuberosity thickness, radio-ulnar space, and radial tuberosity-ulnar space were made using simultaneous tracker lines and a standardised technique. The presence or absence of enthesophytes and the presence of a single or double DBT were noted.26 3-T MRI scans of 26 elbows with partial DBT tears and 30 3-T MRI scans of 30 elbows without pathology were included. Basic demographic data was comparable between the two groups. The tear group showed statistically significant larger mean measurements for radial tuberosity length (24.3mm vs 21.3mm, p=0.002), and radial tuberosity thickness (5.5mm vs 3.7mm, p=<0.0001. The tear group also showed statistically significant smaller measurements for radio-ulnar space (8.2mm vs 10.0mm, p=0.010), and radial tuberosity-ulnar space (7.2mm vs 9.1mm, p=0.013). There was a statistically significant positive correlation between partial DBT tears and presence of enthesophytes (p=0.007) as well as between partial DBT tears and having two discrete DBTs rather than a single or interdigitating tendon (p=<0.0001).Larger radial tuberosities, and smaller radio-ulnar and radial tuberosity-ulnar spaces are associated with partial DBT tears. This may be due to chronic impingement, tendon delamination and consequent weakness which ultimately leads to tears. Enthesophytes may be associated with tears for the same reason. Having two discrete DBTs that do not interdigitate prior to insertion is also associated with partial tears.