Introduction:

The presence of symptomatic lumbar facet cysts has been associated with segmental instability. Given this association, decompression vs decompression with fusion is a frequently debated topic. Multiple grading scales have been devised to identify patients at high risk for development of cyst recurrence, however there exists no external evaluation of these scales.

Methods:

A retrospective review of 54 patients undergoing initial treatment for lumbar synovial cysts at a single institution over the past twelve years was conducted. Surgical treatment consisted of decompression with cystectomy without fusion. Patients were assessed and classified according to the NeuroSpine (NSURG) and Rosenstock Classification systems. Five neurosurgeons reviewed the preoperative MRI’s and results were classified. Inter-rater reliability was assessed using both Gwets AC1 coefficient and Krippendorff’s-a. A one way ANOVA was utilized to evaluate predictive ability of both classification systems.

Results:

In total, of the 54 patients who underwent decompression 7 had cyst recurrence. Overall cyst recurrence was most common in NSURG grade 2 cysts (3/12, 25%) followed by grade 1 cysts (4/27, 14.8%). Of the NSURG grade 3 and 4 patients none had cyst recurrence. In the Rosenstock grades the most common recurrence was in grade 3 cysts (1/4, 25%) followed by grade 1 cysts (5/26, 19.2%). Interrater reliability demonstrated good reproducibility on Gwet’s AC1 and Krippendorff’s alpha on both grading scales. Neither score were predictive of cyst recurrence (P>0.05).

Conclusion:

The Rosenstock and NeuroSpine scores demonstrate good overall inter-rater reliability, however are inconsistent in their ability to predict recurrence of lumbar facet cysts.