Minimally invasive surgical treatment of lumbar synovial cysts

Synovial cysts are a rare cause of lumbar radiculopathy and back pain. Surgical treatment is directed at complete excision of the cyst. We used minimally invasive surgical techniques for a series of patients, to assess the effectiveness of this approach for resection of synovial cysts.

Seventeen patients (10 female and 7 male patients) with presumed synovial cysts, as indicated on magnetic resonance imaging scans, underwent surgical resection with the 18-mm METRx tubular retractor system (Medtronic Sofamor Danek, Memphis, TN). A unilateral approach was used, with either an operating microscope (13 cases) or a magnifying endoscope (4 cases), depending on the preference of the surgeon. Outcomes were reported by using modified MacNab criteria.

The average patient age was 64 years (range, 46-82 yr). The L4-L5 level was most commonly affected (82% of cases). Grade 1 spondylolisthesis at the level harboring the synovial cyst was observed for 47% of the patients; all cases of spondylolisthesis involved the L4-L5 level. The mean operative time was 97 minutes, and the average blood loss was 35 ml. Excellent or good results were achieved for 94% of the patients. A dural tear that did not violate the arachnoid membrane occurred during surgery for one patient but did not require further treatment.

Synovial cysts can be effectively treated with a tubular retractor system in conjunction with an endoscope or microscope. Use of the tubular retractor minimizes soft-tissue trauma, incision length, blood loss, and disruption of ligamentous and bony structures. This may be particularly significant when synovial cysts are associated with spondylolisthesis, minimizing the risk of progressive instability and the need for fusion.