Surgical Treatment for Atlantoaxial Osteoarthritis (AAOA): A Prospective Study of Twenty-Seven Patients
Abstract
PURPOSE OF THE STUDY Atlantoaxial osteoarthritis (AAOA) is a clinical syndrome with signs distinctly different from those of degenerative sub - axial spine disease. Its diagnosis may long be delayed, partly because of insufficient knowledge and partly due to difficulties in interpreting both anteroposterior and lateral radiographs.
The aim of this prospective study was to evaluate the first 27 AAOA patients treated at our department. MATERIAL From 2001 we performed atlantoaxial fixation with fusion in a total of 29 patients with painful arthritis of the atlanto axial complex.
The 27 patients treated before the end of 2010 were enrolled in the study and analysed in detail. This group included 13 women and 14 men aged between 35 and 72 years, with an average age of 53.5 years.
In all patients atlanto - axial fixation was performed using the polyaxial screw-rod system according to Harms. METHODS The patients were followed up at 6 and 12 weeks, 6 and 12 months and then once a year after surgery.
X-ray examinations were done at the same intervals as clinical examinations; functional radiographs were made at 12 to 14 weeks after surgery. The definitive analysis of the group was made in the range of 4 to 59 months (average, 25.7 months) after the primary operation.
Patients' subjective evaluation was based on NPDI and VAS scores and a question of whether the patient would undergo the surgery again. Objective evaluation included clinical outcomes - pain and neurological findings; radiographic results - stability and healing of C1-C2 fusion; and complications during surgery and in early and late postoperative periods.
As intra-operative complications were regarded those associated with the surgical approach, nerve injury and vertebral artery injury. Early post-operative complications included poor wound healing and changes in the patient's neurological status, late complications included instrumentation failure and infection.
Patients' clinical status (NPDI, VAS) was statistically evaluated using the one-way ANOVA. RESULTS The mean VAS score was pre-operatively 7.0 and post-operatively 5.6 at 3 months, 5.0 at 6 months, 5.1 at 1 year; 3.9 at 2 years and 4.0 at 3 years.
The mean NPDI value was pre-operatively 39.6 and post-operatively 38.7 at 3 months, 36.0 at 6 months, 34.5 at 1 year, 34.3 at 2 years and 33.1 at 3 years. The question of willingness to undergo the same operation again was answered in the affirmative by 21 patients (77.8%), in the negative by five (18.5%) and one patient did not know (3.7%).
Complete bone fusion, as assessed by radiography or CT scanning, was achieved in 26 out of 27 patients (96.3%). In one patient the result was ambiguous but, at 3 months as well as the next follow-ups, C1-C2 complex stability was found.
DISCUSSION All patients in our group underwent a unified system of clinical, radiological, CT and MRI examination. In the decisionmaking process, emphasis was placed on a correlation of clinical findings with CT scanning results.
All patients were operated on from the posterior approach using the Harms method, and radiological outcomes were similar to those of Grob et al. who used the Magerl s technique of C1-C2 fixation. The VAS and NPDI scores demonstrated significant improvement as early as 3 post-operative months, with still further improvement in the following period.
The stable clinical status of the patients was achieved at 2 years after surgery. From the practical standpoint we were interested in an answer to the question of whether the patients would be willing to undergo the procedure again.
Almost 80% of affirmative answers testified to the correct choice of treatment. The values found corresponded to those reported by Grob at al.
CONCLUSIONS Patients with painful osteoarthritis refractory to conservative treatment will benefit from atlantoaxial fixation and fusion. For the patient, restricted cervical rotation is acceptable in return for pain relief.
From the surgical point of view, the risk of complications associated with the operative technique did not exceed a tolerable rate.