Tardy radial nerve palsy caused by pseudoarthrosis of humeral shaft

Abstract

1. IntroductionBecause of its close proximity, the radial nerve can be injuredwhen a displaced fracture of the humeral shaft occurs. Delayedradial nerve palsy is very rare. However, we report a case in whichthepalsypresentedmorethan3yearsafterthefirstoperation,andwas due to chronic entrapment of the radial nerve by thedevelopment of fibrous tissue.2. Case reportA 24-year-old man was involved in a high-speed motor vehicleaccident, and sustained a closed mid-shaft fracture of the righthumerus (AO/ASIF classification type B2: Fig. 1). Fixation wasperformed 3 days after injury, using an antegrade intramedullarynail and Russell–Taylor device (R–T: Smith & Nephew, Memphis,MO, USA). Postoperative hypoaesthesia of the radial nerve regionnoted, but this resolved within 1 month. At 10 months post-operativelythefracturestillshowednon-union,butthemancouldnot attend our hospital because of the demands of his job.However,3yearsand 4monthsafter theoperation heexperiencedacute-onset paresis and hypoaesthesia (5/10) in the area suppliedby the radial nerve, with decreased wrist strength and fingerextension (MMT level 2) while he was playing the drums as ahobby. The nerve percussion test was positive in the left posteriorregion of the humerus. On radiography, the fracture site showedpseudoarthrosis with incomplete callus (Fig. 2). A nerve conduc-tion study revealed conduction block of the radial nerve at theposterolateral part of the callus (Fig. 3). Scintigraphy showed a hotregion on the right humeral stem (Fig. 4). A diagnosis was made oftardy radial nerve palsy caused by pseudoarthrosis of the righthumeral shaft fracture.Thesymptomshadnotimprovedby6weeksafteronsetdespiteconservative treatment, and a second operation was carried out.The radial nerve trunk was found to be compressed by fibroustissue at the callus site. The R–T was removed and bone graftingwith decompression of the radial nerve was performed, followedby replantation using an unreamed humeral nail (Synthes,Bettlach, Switzerland). At 4 weeks after this procedure, thesymptoms had improved. Nerve conduction had recoveredcompletely at 6 months (Fig. 3) and, at 18 months, the fractureshowedunion.Thedevicewasremovedat24monthsfollowingthesecond operation (Fig. 4). At the last follow-up examination at 42months, the man had no complaints, showed full range of motionof the shoulder and elbow with no neurological defects and couldwork unhindered.3. DiscussionConservative treatment is the first choice for humeral shaftfracture. However, pseudoarthrosis sometimes develops in trans-verse or short spiral fractures,so that recentlymore stable fixationusinganintramedullary nailhas been favoured.Radial nerve palsycan occur in 2–18% of humeral shaft fractures, but neurotmesis, orentrapment of the nerve trunk, occurs in only 5% of cases withoutopen fracture. Hence conservative treatment is favoured.