The Results of Anterior Screw Fixation in Odontoid Fractures: Comparison of the Results on the Number of Screws / 대한척추외과학회지

ABSTRACT

STUDY DESIGN: A retrospective study was performed in 22 cases undergoing anterior screw fixation for type II odontoid process fracture. OBJECTIVES: To determine the utility of anterior screw fixation for type II odontoid process fracture and assess the influence of several factors including the number of screw on results. SUMMARY OF BACKGROUND DATA There are few data on the surgical results of type II odontoid process fracture in Korea. MATERIALS AND METHODS: Between Jan. 1987 and Jan. 1997, 24 patients were operated by anterior screw fixation for the type II odontoid process fracture, but 2 patients were lost to follow-up and we analyzed 22 patients with average 68 month followup(range 24~142 months). Nine patients were operated by anterior fusion using one screw(group I) and 13 patients using two screws(group II). There were 19 fresh odontoid fractures, 3 delayed union preoperatively. The amount of correction of initial displacement and angulation, bone union and perioperative complications were selected as assessment criteria. Eric and James' functional outcome scale was used for the functional results. The statistical analysis using the two-way ANOVA and chisquare test was performed. RESULTS: In clinical results, excellent functional outcome were obtained in 6 cases of group I and 10 cases of group II, while good functional outcome in 3 cases of group I and 3 cases of group II according to Erric and James' criteria(p=0.477). There was no case with fair or poor results in both groups including nonunited case. In radiological results, union rate was 86.4%(19 patients) totally, 67%(6 patients) in group I and 100%(13 patients) in group II retrospectively(p=0.045). The mean time to fusion was 11.3 weeks in all cases and there was no difference between both groups(p=0.521). In all cases, reduction rate was 4.0mm(displacement in lateral view), 1 . 5degree(angulation in lateral view), 1.5degree(angulation in open mouth view) postoperatively, being 5.7mm, 2.5degree, 2.8degreein group I and 3.6mm, 3 . 8degree, 0.6degreein group II. There was no significant differences between both groups(p=0.164, p=0.794, p=0.235). SUMMARY: Anterior screw fixation was clinically and radiologically reliable surgical treatment option for type II odontoid process fracture. Speaking of the number of screw used in anterior screw fixation, two screw group showed better results in union rate.