Indications Access provides exposure to posterior aspect of the radial shaft Indications ORIF of radial shaft fractures using extensor side of bone access to the PIN as it passes through the arcade of Frohse for nerve paralysis resistant tennis elbow radial osteotomy osteomyelitis and bone tumor resection/biopsy Internervous Plane Proximally between ECRB (radial nerve) EDC (pin nerve) Distally between ECRB (radial nerve) EPL (pin nerve) Preparation Position place patient supine if arm is abducted to the side on an arm board, the forearm should be pronated if arm is adducted across the chest, the forearm should be supinated Approach Landmarks Proximal lateral epicondyle of the humerus Distal dorsoradial tubercle (Lister's tubercle) Incision starting point is anterior and distal to the lateral epicondyle of the humerus straight or gently curved incision along the dorsolateral aspect of the forearm be aware of superficial radial nerve and cephalic vein distally end incision just distal and ulnar to Lister's tubercle Superficial dissection proximal third incise fascia in line with skin incision using interval between ECRB and the EDC to reveal supinator middle third identify the abductor pollicis longus (APL) and extensor pollicis brevis (EPB) emerging between ECRB and EDC distal third undermine the APL and EPB tendons medially to identify plane between EPL and ECRB Deep dissection proximal third identify the insertion of supinator by turning arm into full supination supination moves the PIN away from area of deep dissection incise insertion of supinator along radius and subperiosteally strip supinator off bone to expose proximal third of radius for more proximal exposures, two deep approaches exist to protect PIN: dissecting proximal to distal: detach origin of ECRB and ECRL from lateral epicondyle and identify and dissect PIN as it enters supinator muscle dissecting distal to proximal: identify nerve as it exits supinator and dissect it proximally out of supinator substance middle third make incision along superior and inferior borders of APL and EPB retract them off bone to expose middle third of radius distal third separating the ECRB and EPL will directly lead to the lateral border of the radius part of the interosseous membrane may have to be removed to approach the radius Dangers Posterior interosseous nerve (branch of radial nerve) injury usually from retraction in 25% of patients the nerve actually touches the dorsal aspect of the radius plates placed high on the dorsal surface may trap the nerve PIN must be identified within the supinator muscle Posterior interosseous artery accompanies the PIN along the interosseous membrane in the proximal 1/3 of radius