A Cadaveric Analysis of Tunnel Position Created Using Flexible Versus Rigid Instrumentation in a Single-Incision Distal Biceps Tendon Repair

Abstract

This study was designed to determine whether the use of a flexible guide pin and reamer through an anterior single-incision approach would allow for a more anatomic insertion point on the radial tuberosity when compared with the traditional rigid instrumentation used for cortical button fixation. Seven matched pairs of fresh-frozen cadaveric upper extremity specimens were used in this study. One specimen from each matched pair was randomly assigned to undergo a simulated repair using the standard instrumentation required for a cortical button fixation device, and the other specimens were assigned to undergo the same repair using a 42° anterior cruciate ligament femoral guide with a flexible guide pin and reamer. Each specimen from both groups was positioned with the elbow in 90° of flexion and the forearm maximally supinated during guide pin insertion. The proximal portion of the radius was then harvested from the specimen and scanned using micro-computed tomography (micro-CT). Tunnel position between the 2 techniques was compared with the center of the native tendon footprint. The mean percentage of the reamed entry hole within the tendon footprint was significantly less using rigid instrumentation (36.35%) compared with flexible instrumentation (67.29%) (P = .043). Furthermore, when flexible reamers were used (mean offset ratio, 0.17), the resultant tunnel was positioned in a significantly more central position within the radial shaft (i.e., the offset ratio was lower) compared with rigid reamers (mean offset ratio, 0.35) (P = .043). The entry hole was found to be significantly more posterior relative to the center of the anatomic footprint for the flexible reamer group (mean, 0.21 mm anterior) compared with the rigid reamer group (mean, 3.22 mm anterior) (P = .028). There was no difference in tunnel length between the 2 groups. The use of a flexible guide pin and reamer allows for a more anatomically positioned repair than does rigid instrumentation through a single-incision approach. This surgical technique allows for a more anatomic re-creation of the distal biceps tendon insertion while maintaining the benefits of a single limited anterior exposure.