Abstract

Background: Posterior interosseous nerve (PIN) palsy following elbow surgery is uncommon and most frequently attributed to iatrogenic injury during radial head procedures requiring lateral exposure. Delayed PIN palsy arising after isolated olecranon fixation via a strictly posterior approach—without lateral dissection—is exceedingly rare. This presentation may reflect postsurgical inflammatory neuropathy (neuralgic amyotrophy, NA) rather than a direct surgical insult. Case presentation: A 26-year-old male truck mechanic sustained a work-related intraarticular comminuted displaced olecranon fracture (AO/OTA 21-B1.3) with an intact coronoid process. Preoperative neurovascular examination was normal. Open reduction and internal fixation was performed on 11 July via a posterior approach using a precontoured olecranon locking plate (Acumed). Neurological examination was normal on postoperative day 1 and at week 2. At postoperative week 3, the patient developed sudden complete inability to extend his fingers (MRC 0/5) with preserved wrist extension and finger flexion (5/5), without compartment syndrome. The patient had undergone prolonged immersion of the left forearm in very hot water the day before symptom onset. Results: Electromyography at postoperative week 6 confirmed very severe axonotmesis of the left PIN. Conservative management was instituted: dorsal extension orthosis and oral prednisolone 60 mg/day for two weeks with progressive tapering. Initial clinical motor recovery was recorded at week 18. Serial electromyography demonstrated proximal reinnervation polyphasia at week 23 and active global reinnervation at week 32. Complete motor recovery was achieved by week 48. Elective plate removal was subsequently performed without recurrence. Conclusion: Delayed PIN palsy after olecranon fixation with a normal early postoperative course is inconsistent with iatrogenic nerve injury and should prompt consideration of postsurgical inflammatory neuropathy. Recognition of this entity supports conservative management, avoids unnecessary surgical re-exploration, and enables timely initiation of corticosteroid therapy

Keywords

posterior interosseous nerve, olecranon fractures, neuralgic amyotrophy, parsonage–turner síndrome, axonotmesis, electromyography, peripheral nerve injuries, corticosteroids