Regression of an atlantoaxial rheumatoid pannus following posterior instrumented fusion

•Atlantoaxial rheumatoid pannus significantly regressed by 44.44% over 8.02 months.•Nurick score, but not the Ranawat score, significantly improved postoperatively.•Posterior fusion may be an appropriate surgical treatment for rheumatoid pannus.

ObjectiveRheumatoid patients may develop a retrodental lesion (atlantoaxial rheumatoid pannus) that may cause cervical instability and/or neurological compromise. The objective is to characterize clinical and radiographic outcomes after posterior instrumented fusion for atlantoaxial rheumatoid pannus.MethodsWe retrospectively reviewed all patients who underwent posterior fusions for an atlantoaxial rheumatoid pannus at a single institution. Both preoperative and postoperative imaging was available for all patients. Anterior or circumferential operations, non-atlantoaxial panni, or prior C1–C2 operations were excluded. Primary outcome measures included Nurick score, Ranawat score (neurologic status in patients with rheumatoid arthritis), pannus regression, and reoperation. Pannus volume was determined with axial and sagittal views on both preoperative and postoperative radiological images.ResultsThirty patients surgically managed for an atlantoaxial rheumatoid pannus were followed for a mean of 24.43 months. Nine patients underwent posterior instrumented fusion alone, while 21 patients underwent posterior decompression and instrumented fusion. Following a posterior instrumented fusion in all 30 patients, the pannus statistically significantly regressed by 44.44%, from a mean volume of 1.26 cm3 to 0.70 cm3 (p < 0.001), over 8.02 months. The Nurick score significantly improved from 2.40 to 0.60 (p < 0.001), but the marginal improvement of 0.20 in the Ranawat score did not reach significance (p = 0.312). Six patients (20%) required reoperations over a mean of 13.18 months. Reoperations were indicated for C1 instrumentation failure in four patients and pseudoarthrosis in two patients.ConclusionFollowing posterior instrumented fusion, the pannus radiographically regressed by 44.44% over a mean of 8.02 months, and patients clinically improved per the Nurick score. The Ranawat score did not improve, and 20% of patients required reoperation over a mean of 13.18 months. The annualized reoperation rate was approximately 13.62%.