Selective 360° percutaneous extensor carpi radialis brevis tendon release for tennis elbow: an experimental study

The purpose of this study was to define in volunteers and cadavers the positions of structures at risk and the extensor carpi radialis brevis (ECRB) origin limits for sonographically guided percutaneous tendon release in tennis elbow. First, in volunteers, we used Doppler sonography to determine the position (danger zone) of the structures at risk (neurovascular bundle and radial collateral ligament) from the most lateral point of the epicondyle (point of entry). Second, in cadavers, we studied the footprint of the ECRB's origin for finally performing sonographically guided tendon release (1- to 2-mm incision) away from the danger zone. Efficacy was measured in terms of detachment ratios for the ECRB and safety as the absence of neurovascular bundle or radial collateral ligament injuries. In 10 volunteers (20 elbows), the neurovascular bundle was located 18.1 mm or greater anteromedially from the point of entry. The neurovascular bundle was not in direct contact with the bone. In 13 formaldehyde-embalmed cadaver elbows, the distance between the origin of the ECRB and the radial collateral ligament was 0 mm or greater. The anterior origin of the ECRB did not contact the neurovascular bundle. The maximum attachment limits of the ECRB were at 15, 5, 15, and 16 mm from the point of entry (anterior, posterior, proximal, and distal margins, respectively). Average detachment ratios were excellent for anterior and distal margins and good for posterior and proximal margins, without neurovascular bundle or radial collateral ligament injuries. This study determined a danger zone to avoid and an area of probability in which to enclose most of the ECRB's origin for sonographically guided percutaneous tendon release. A 360° ECRB detachment can be performed safely and effectively. Clinically, sonographically guided percutaneous tendon release should selectively target pathologic regions.