[Occipitocervical fixation: long-term follow-up in fifty-seven patients]

Abstract

Purpose of the study: Occipitocervical fixation and spondylodesis is indicated in various cases of occipitocervical instability. The aim of this retrospective study was to evaluate the results of occipitocervical fixation at our institutions.

Material: Between 1997 and 2007, a total of 57 patients underwent occipitocervical fixation (OC) there were 25 men and 32 women, from four to 77 years of age, with an average of 58.7 years. The patients were allocated to two groups according to the method of OC fixation used: tying wires or cables (group 1) screw-rod or screw-plate systems (group 2). Indications for OC fixation included trauma in 15, rheumatoid arthritis (RA) in 28, destruction due to psoriasis in one, tumour in eight, and congenital anomalies of the cervico-cranial junction in five patients. In five patients with tumour, OC fixation was completed with a transoral or transmandibular procedure. The C0-T 1 or C0-T 2 segments were fixed in 22 patients, C0-C2 segments in 14, C0-C3 segments in six, C0-C4 segments in two, C0-C5 segments in eight and C0-C6 segments in five patients.

Methods: In atlanto-occipital dislocation, comminuted fractures of the ;atlas or similar injuries, C0-C1-C2 segments were fused in congenital anomaly, the C0-to-lower cervical spine was fixed, with C1 being avoided. The RA patients were treated by fixation of the C0 to T1 or T2 segments. The atlas was fixed by the screw method of Goel, the C2 joint by that of Judet, or stable fusion of the two vertebrae was carried out by the Magerl transarticular technique. For the middle and lower cervical spine, lateral mass screw fixation by the Magerl method was used, and from C7 caudally the vertebrae were fixed transpedicularly. Occasionally, in small children in particular, a Ransford frame fixed with wires or cables was used. In principle, an extent of fixation as small as possible was employed. The patients were evaluated at a final follow-up ranging between 12 and 132 months after the primary surgery (average, 42.7 months). Indications for surgery and the method and extent of instrumentation were recorded. The evaluation included pain and neurological deficit assessment, radiographic evidence of the stability of fixation and bone union and intra-operative and early and late post-operative complications.

Results: Of the 57 patients, bone fusion was the objective of surgery in 52. Further five patients died of associated injuries or serious medical complications shortly after the operation. Of the remaining 47, bone union was achieved in 44 patients (93.6%). Pseudoarthrosis developed in three patients who, however, because of a higher age and minimal complaints did not require revision surgery. In terms of bone union, there was no difference between a short (C0-C2) and a long (C0-CX or C-T) fixation. No differences among fixation materials were found. The differences in percent bone union after spondylodesis between the tying-wire and screw-rod fixation systems were not statistically significant (p > 0.05). In the patients treated for RA, psoriasis or congenital anomaly, the Nurick scale score significantly improved at 2 years after surgery (p < 0.05). In comparison with the others, the RA patients had a significantly higher number of complications (p < 0.05). The patients treated for tumour showed a significant difference between the pre- and post-operative VAS values (p < 0.05).

Discussion: Of the patients with RA, psoriasis or congenital anomaly, 57.6% showed post-operative improvement in the Nurick scale score by 1-2 but never more than by 2. A decrease in pain intensity and neurological findings was recorded in 88.2% of the patients. This is in agreement with the results published in the international literature. In the patients treated for trauma, a high proportion (53.3%) had neurological deficit, which is unusually high for craniocervical injuries. This can be explained by the fact that OC fixation is used only in the most serious injuries. Of five patients with neurological deficit of Frankel grade A or B, three died and two required mechanical ventilation. Less serious neurological findings of Frankel grade C or D in three patients improved to a normal condition.

Conclusions: Rigid OC fixation is a very effective method for the treatment of craniocervical junction instability. The currently used implants allow us to achieve high stability and efficiency of bone union. Regardless of the instrumentation used, fusion is achieved in more than 90%, and clinical improvement in more than 80% of the patients.