Treatment of O dontoid Fractures with Single Anterior Screw Fixation / 대한정형외과학회잡지

PURPOSE: To evaluate the availability and safety of single anterior screw fixation in the treatment of type II and III odontoid process fractures through an analysis of the treatment outcomes. MATERIALS AND METHODS: This study analyzed 16 patients who underwent surgery between May 1996 and Oct. 2003 by single anterior screw fixation for type II and III odontoid process fractures with at least a 1 year follow up. The radiographic findings such as the fusion rate, union time, changes in the fracture shape, and metal migration were evaluated. In addition, the Robinson modification criteria were used for the clinical assessment. RESULTS: There were 12 and 4 patients with Anderson and D'Alonzo type II and type III fractures, respectively. Of the 16 patients, 15 (93%) achieved bony union after an average of 13.8 weeks. There were 2 cases of malunion with a normal range of cervical motion, and 1 case requiring posterior fusion as a result of nonunion. A full range of cervical motion was maintained in 11 cases. Three cases had a limitation of less than 25% and 2 cases had a limitation greater than 25%. CONCLUSION: Single anterior screw fixation is an effective treatment modality with a high fusion rate and low complication rates. However, precise preoperative planning and technical experience is essential for preventing unwanted complications.

Anterior Screw Fixation using Herbert Screw for Type II Odontoid Process Fractures

OBJECTIVE: Anterior screw fixation provides the best anatomical and functional results for type II odontoid process fracture (type II-A, II-N, and II-P) with intact transverse ligament. The purpose of this study is to evaluate the usefulness of the 4.5mm diameter, cannulated Herbert screw in anterior screw fixation. METHODS: From Jan. 2003 to Feb. 2004, consecutive 10cases of type II odontoid process fractures were treated with anterior screw fixation using a Herbert screw. The Herbert screw has double threads, with different pitches on the distal and proximal ends. It has no head, so it can be inserted through articular cartilage and buried below bone surface. It was originally developed for treating scaphoid fractures. RESULTS: There were 8male and 2female patients whose ages ranged from 15 to 67years (mean 42.1years). The fracture type was type II-A in 4patients, II-N in 3patients, and II-P in 3patients. The fracture line was oblique downward and backward in 6cases, oblique downward and forward in 1case, and horizontal in 3cases. The range of follow-up was 5 to 18months (mean 12months). Bone fusions were achieved in all cases without any instrumental failures or postoperative complications. CONCLUSION: The Herbert screw is very useful in anterior fixation for type II odontoid process fracture. This series showed successful results also in type II-A odontoid fracture when treated with the Herbert screw, but further more studies are required.

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

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.

Strategies for Anterior Screw Fixation for Type II Odontoid Process Fracture, and Long-Term Follow-up Results

Type II fracture of the odontoid process is the most common form of axis fracture, and because of the difficulty in healing, its results may be fatal. The authors subclassified these fractures as anteriorly displaced(type II-A), posteriorly displaced(type II-P), and non displaced(type II-N). Twelve patients with type II fractures underwent anterior screw fixation : three were type II-A : one, type II-P : and eight, type II-N. The mean duration of follow-up was 29.3 months, and all patients except two showed good alignment and stable fixation : these exceptions were type II-A, with 9mm displacement, and showed delayed failure of screw fixation. All type II-N, II-P, and II-A, with 3mm displacement, were successfully treated. We conclude that selection of the treatment modality should be based on the direction of displacement of odontoid process. For type II-N, II-P and II-A fractures, where displacement is mild, anterior screw fixation is a reliable method, but for type II-A fracture, with severe displacement, posterior fixation should be considered.

Clinical Evaluation of Direct Anterior Screw Fixation of Odontoid Fractures

dontoid fractures have been treated either conservatively or by surgical fixation, and whether one method is better than the other is still controversial. Because it more effectively overcomes the problems of fracture instability and nonuinon, operative stabilization is now favored over external immobilization for the treatment of Type IIodontoid fractures. Most surgical stabilizations of such fractures use posterior cervical wiring techniques with C1-C2 arthrodesis; these, however, obliterate the rotation and flexion/extension of the atlantoaxial complex,and in Type II-P fractures, provide little resistance to further posterior subluxation. As no arthrodesis is performed, direct anterior screw fixation of odontoid fractures theoretically stabilizes the atlantoaxial complex and preserves its motion. Between January 1993 and December 1996, we performed eleven anterior screw fixations in patients who had suffered odontoid fractures(Type II, III); these were postoperatively followed up for an average of 27 months. Excepet for two cases of permissible malunion, thought to be due to fixation on a partially reduced state, all eleven cases showed firm union at the fracture site, with no significant disabilities and complications. The results indicate that in odontoid fracture reduction and eventual fracture union, the outcome of anterior screw fixation is excellent; there is, in addition, no decrease in cervical motion, a disadvantage inherent in currently accepted methods of treatment.