NEUROLOGICAL DEFICIT FOLLOWING ACETABULAR FRACTURES: THE DOUBLE CRUSH SYNDROME

Abstract

Purpose: To document the incidence of neurological lesions and functional outcome following displaced acetabular fractures.

Patients and Methods: Prospective review of patients who underwent stabilisation of acetabular fractures in a University Hospital trauma centre. From December 1994 to November 2000 136 patients were identified with acetabular fractures. The open reduction and internal fixation of the acetabular fixation was performed by standard operative techniques. The time from the initial injury to the operation ranged from 24 hours to I4days. Patients with sciatic nerve injuries were prospectively followed up and long-term outcome recorded. Weakness or absence of dorsiflexion or plantar flexion was graded according to the standard Medical Research Council. Abnormalities of sensation, including absent or diminished sensation to light touch and pinprick as well as dysesthesia or hyperesthesia of the dorsal and plantar aspects of the foot were recorded. None of the patients had an injury of the spinal cord. Intra-operative monitoring was performed in most cases, and routine electromyography and nerve -conduction studies were done post-operatively and at least on one more occasion to record the level and severity of the lesion and to monitor progress of recovery. All the patients were followed up clinically in the trauma clinics and functional improvement was routinely assessed. The mean follow up of the patients was 3.4 years (range 1.5–6 years).

Results: Out of 136 patients who underwent stabilisation of acetabular fractures there were 27 (19.8 %) cases of neurological lesions. In 12 cases the femoral head was dislocated posteriorly. Twenty were men and eight were woman. The mean age was 33.8 (range 16–66). 15 patients had associated injuries. The mean ISS was 12.6 (range 9–34). At initial presentation there were 13 patients with a complete dropped foot lesion, 10 patients with foot weakness and 4 patients with burning pain and altered sensation over the dorsum of the foot. Intra-operative monitoring was performed in 16 cases. All the patients had EMG studies for neurophysiological assessment of the lesion. EMG studies revealed sciatic nerve lesions in all the cases but in nine patients with a dropped foot there was evidence of a proximal (sciatic) and distal (neck of fibula) lesion, “double crush syndrome”. Only in 3 of these cases there was documentation of an ipsilateral knee injury. In two patients there was deterioration of foot function after surgery due to iatrogenic damage. At final follow-up, clinical examination and associated EMG studies revealed full recovery in 5 cases with initial muscle weakness (mean time 4.2 years (2–5)) and complete resolution of sensory symptoms (burning pain and hyposthesia) in 4 cases (mean time 3 years (2–4)). There was improvement of functional capacity (motor and sensory) in two cases with initially complete drop foot and in 4 cases with muscle foot weakness (mean time 3.6 years (range 2–6). In 11 of the cases with dropped foot (all nine with “double crush”) at presentation, there was no improvement in function, (mean time 3.9 years (range 2–6).

Conclusion: Acetabulum fractures associated with sciatic nerve injuries continue to be a significant cause of long-term morbidity in trauma patients. In cases where there is evidence of “double crush lesions” the prospect of functional recovery is low as seen in this group of patients. Single lesions appear to be associated with a more favourable prognosis.