Functional consequence of distal brachioradialis tendon release: a biomechanical study

Abstract

Purpose: Open reduction and internal fixation of distal radius fractures often necessitates release of the brachioradialis from the radial styloid. However, this common procedure has the potential to decrease elbow flexion strength. To determine the potential morbidity associated with brachioradialis release, we measured the change in elbow torque as a function of incremental release of the brachioradialis insertion footprint.

Methods: In 5 upper extremity cadaveric specimens, we systematically released the brachioradialis tendon from the radius and measured the resultant effect on brachioradialis elbow flexion torque. We defined release distance as the distance between the release point and the tip of the radial styloid.

Results: Brachioradialis elbow flexion torque dropped to 95%, 90%, and 86% of its original value at release distances of 27, 46, and 52 mm, respectively. Importantly, brachioradialis torque remained above 80% of its original value at release distances up to 7 cm.

Conclusions: Our data demonstrate that release of the brachioradialis tendon from its insertion has minor effects on its ability to transmit force to the distal radius.

Clinical relevance: These data imply that release of the distal brachioradialis tendon during distal radius open reduction internal fixation can be performed without meaningful functional consequences to elbow flexion torque. Even at large release distances, overall elbow flexion torque loss after brachioradialis release would be expected to be less than 5% because of the much larger contributions of the biceps and brachialis. Use of the brachioradialis as a tendon transfer donor should not be limited by concerns of elbow flexion loss, and the tendon could be considered as an autograft donor.

Figure 1

Limb dissection with all muscles except BR removed. Note the fibrous connections between the BR and the radius that can transmit force to the radius at release distances proximal to the tendinous insertion. Inset: Close-up view of the Krackow stitch used to secure the BR tendon.

Figure 2

Experimental setup for biomechanical testing of BR torque production. The elbow was placed at 90 degrees of flexion and the forearm was placed in neutral rotation. This orientation was fixed with Schanz screws and a Kirschner wire to prevent elbow rotation and forearm pronation/supination.

Figure 3

Close-up view of BR insertion. Successive BR releases progressing proximally from the radial styloid can be seen as individual incisions. Releases were performed as shown by transecting the tendon and soft tissue through the periosteum.

Figure 4

Graphical representation of mean torque as a function of release distance (n=5 specimens). Torque is expressed relative to the maximum torque generated by placing a 20 N load on the BR tendon. It can be seen that release distances up to 15mm result in virtually no loss of torque production. Note that, even at large release distances, BR force production would be expected to decrease by less than 20%. The shaded region corresponds to the BR tendon insertion footprint, as previously described (2). Note that the vertical axis origin extends to 75% maximum.

Figure 5

Mean BR tendon stiffness as a function of release distance (n=5 specimens). This graph summarizes the overall stiffness change of the BR tendon with at different release distances. Stiffness increased at small release distances, reflecting a decrease in tendon length without loss in force production capacity.