Case Series: MILD® Procedure as a Minimally Invasive Option for Lumbar Synovial Cyst Decompression

Lumbar synovial cysts are benign, fluid-filled lesions arising from the facet joints, often associated with degenerative changes and segmental instability. These cysts can cause neurogenic claudication and radiculopathy, significantly limiting mobility and quality of life. While traditional treatments include conservative management, injections, aspiration, and open surgery, each has notable limitations. The Minimally Invasive Lumbar Decompression (MILD®) procedure, originally designed for lumbar stenosis, may offer a less invasive alternative for synovial cyst resection, especially in patients who are poor candidates for extensive surgery.

Three patients with symptomatic lumbar synovial cysts refractory to conservative therapy underwent the MILD® procedure. The first, a 68-year-old man with an L4-5 cyst, experienced minimal relief from injections but showed marked improvement in walking and standing tolerance after MILD®, with magnetic resonance imaging (MRI) at one year demonstrating significant cyst reduction and canal restoration. The second, a 73-year-old man with bilateral radiculopathy and an L4-5 cyst, reported substantial functional gains, walking up to one hour at 12 weeks post-procedure. The third, an 80-year-old woman with multifactorial stenosis and a right L4-5 cyst, underwent 2-level MILD® decompression, resulting in improved ambulation and standing capacity at follow-up.

The MILD® procedure is a minimally invasive procedure that was associated with clinical improvement in 3 reported cases of patients with lumbar synovial cysts causing neurogenic claudication or radiculopathy after conservative measures failed. This technique may offer the potential for rapid functional recovery and reduced morbidity, which could be particularly advantageous for older adults or those with comorbidities. While larger studies are needed to better establish its safety and efficacy for this indication, these cases suggest that MILD® may be a potential treatment option for symptomatic lumbar synovial cysts.