Submit Manuscript | http://medcraveonline.com usually due to direct trauma [8]. The most common movement in polo riders is alternative pronosupination with the right arm, and forced pronation or supination with the riding arm. Such muscular overuse may lead to injury to PIoN. Case Reports Case report n°1NR, a 38-year-old healthy male, presented with progressive finger extension weakness. He had been training during the amateur polo session, when he noticed pain at the lateral side of his left elbow. The next few days he could not extend completely his third finger. Three months after onset, he reported pain at the left elbow and weakness of wrist and finger extensors. On physical examination, he showed subtle muscle atrophy in the left posterior forearm. Strength examination was 2/5 in extension of the metacarpophalangeal joints. Wrist extension was 3/5, with radial deviation (Figure 1). Sensation and reflexes were intact. Electrodiagnostic studies revealed an axonal-demyelinating lesion of the left PIoN at the elbow, with sparing of proximal radial innervated muscles and preservation of sensory radial nerve. Magnetic resonance imaging (MRI) of the left elbow showed abnormal signal intensity in extensorum digitorum communis and indicis proprius, suggestive of denervation. The patient underwent descompressive surgery, and intraoperative findings confirmed the entrapment (Figure 2). At 6 months follow-up, he was almost completely recovered. Case report n°2HE, a 54 years-old healthy male, noticed a progressive loss of strength in fingers extension and thumb abduction during the last year, beginning in the last three fingers and later involving the others. He was an amateur polo player, and he also used to play tennis. On presentation, he had tenderness over the lateral epycondile, 2/5 weakness of wrist extensors and the metacarpophalangeal joints 2nd to 5th, and radial deviation of the hand (Figure 1). Electrodiagnostic tests and MRI showed similar results to those of patient n°1. The patient was then referred for surgical decompression, with full recovery at 1 year follow-up. AbstractPosterior interosseous neuropathy is an entrapment of the deep branch of the radial nerve in the forearm. The deep branch of the radial nerve is primarily a motor nerve, and compression of this nerve may lead to weakness in finger and thumb extension without sensory abnormalities. We present two cases of polo riders suffering of posterior interosseous neuropathy, confirmed both by electrodiagnostic testing and by surgical exploration in one case. We review the anatomic course and distribution of the posterior interosseous nerve, the clinical picture of its injury, and discuss the probable mechanism of entrapment in polo players.