Surgical treatment and outcomes in 45 cases of posterior interosseous nerve entrapments and injuries

Abstract

The authors report data in 45 surgically treated posterior interosseous nerve (PIN) entrapments or injuries. Forty-five PIN entrapments or injuries were managed surgically between 1967 and 2004 at Louisiana State University Health Sciences Center (LSUHSC) or Stanford University Medical Center. Patient charts were reviewed retrospectively. The LSUHSC grading system was used to assess PIN-innervated muscle function. Injuries were caused by nontraumatic (21 PIN entrapments and four tumors) and traumatic (nine lacerations, eight fractures, and three contusions) mechanisms. Presentations included weakness in the extensor carpi ulnaris muscle, causing compromised wrist extension and radial drift; extensor digitorum, indicis, and digiti minimi muscles with paretic finger extension; extensor pollicis brevis and longus muscles with weak thumb extension; and abductor pollicis longus muscle with rare decreased thumb abduction due to substitutions of the median nerve-innervated abductor pollicis brevis muscle and, at 90 degrees, the extensor pollicis brevis and longus muscles. Preoperative evaluations consisted of electromyography and nerve conduction studies, elbow and forearm plain x-ray films, and magnetic resonance imaging for tumor detection. At surgery, in continuity lesions were found in 21 entrapments and three fracture-related and three contusion injuries; all transmitted nerve action potentials (NAPs) and were treated with neurolysis. Five fracture-related PIN injuries, one of which was a lacerating injury, were in continuity and transmitted no NAPs; graft repairs were performed in all of these cases. Among nine lacerations, three PINs appeared in continuity, although intraoperative NAPs were absent. Two of these nerves were treated with secondary end-to-end suture anastomosis repair and one with secondary graft repair. There were six transected lacerations: three were treated with primary suture anastomosis repair, two with secondary suture anastomosis, and one with graft repair. Four tumors involving the PIN were resected. Most muscles innervated by 45 PINs had LSUHSC Grade 3 or better functional outcomes. Forty-five PIN entrapments or injuries responded well to PIN release and/or repair.