Study Overview

This study analyzed the clinical outcomes of 13 patients treated with the Inspan device over a follow-up period ranging from 14 to 24 months (median 19 months). Patients suffered from chronic LBP with radicular leg pain, and in some cases, neurogenic claudication. All had previously undergone extensive non-surgical management, including physical therapy and epidural steroid injections. Surgical intervention using the Inspan device was performed in an outpatient setting.

Device Characteristics and Surgical Technique

The Inspan device is a titanium-based interspinous distraction fixation system designed to achieve spinal canal decompression and rigid stabilization without the use of pedicle screws. It features dual locking plates with aggressive fixation spikes, a dual interlocking hub, and distraction-compression capabilities. These design features allow for precise segmental alignment, effective decompression, and segmental fixation.

Surgical implantation involved a minimally invasive approach with a 3.5–4 cm posterior incision. Following distraction and preparation of the interspinous space, the device was implanted to restore posterior disc height and relieve neural compression.

Clinical Results

Quantitative pain assessments using the Numeric Pain Rating Scale (NPRS) revealed statistically significant reductions in both back and radicular leg pain:

• Back Pain Improvement: p = 0.000552

• Radicular Leg Pain Improvement: p = 0.000291

No intraoperative or postoperative complications were reported. Notably, none of the patients required reoperation during the follow-up period, and all retained the implanted device without mechanical failure.

Comparative Context and Biomechanical Evidence

The Inspan device is part of a growing class of interspinous distraction with rigid fixation (ISDRF) systems. These devices, distinct from early-generation dynamic spacers, aim to offer immediate segmental stability while facilitating posterior decompression and bony fusion.

Biomechanical studies cited in the paper indicate that ISDRF systems perform comparably to pedicle screw constructs in single-level fusion scenarios. They also demonstrate favorable load distribution, maintenance of motion at adjacent segments, and minimal impact on adjacent facet joints—an important consideration in preserving long-term spine function.

Implications for Clinical Practice

This early data supports the utility of the Inspan system in a select patient population: older adults with symptomatic lumbar stenosis or radiculopathy who may not be ideal candidates for open spinal fusion. The system offers:

• Minimally invasive implantation

• Decompression through posterior distraction

• Avoidance of pedicle screws or interbody cages

• Preservation of future surgical options

Given the absence of complications, low reoperation rates, and statistically significant pain relief, interspinous distraction and fixation systems like Inspan represent a viable surgical alternative in outpatient settings.

Conclusion

The findings from this retrospective study demonstrate the Inspan device’s effectiveness as a safe and practical solution for managing lumbar radiculopathy and back pain. While limited by a small cohort size, the results contribute to a growing body of evidence supporting interspinous fixation as a meaningful advancement in minimally invasive spine care.

Acknowledgment

Special thanks to Soubrata V Raikar, Arun A Patil, Deepak K Pandey, Sidharta R Kumar for their clinical research and contributions to the advancement of minimally invasive spinal technologies. Their work continues to inform and guide the evolving field of outpatient spine surgery.

Read original study: https://pmc.ncbi.nlm.nih.gov/articles/PMC8713432/