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Prospective Randomized Trial of Cortoss Versus PMMA in the Treatment of Vertebral Compression Fractures; Preliminary Results at a Single Center 2006

Interventional Spine

H. Paul Hatten, Jr., MD, Non ASSR Member

Scientific Paper

Purpose

The purpose of this study is to assess the safety and efficacy of Cortoss compared to a commercially available PMMA. This study is being conducted under an FDA Investigational Device Exemption (IDE).

Methods & Materials

This is a prospective randomized study of 300 patients at 19 sites. Patients are randomized into one of 2 groups; treatment with Cortoss or control with PMMA. Patients are blinded to the randomization group in order to remove any possibility of bias in responding to questionaires. Among the inclusion criteria are the requirement for a minimum pain on the Visual Analog Scale (VAS), Oswestry Disability Index (ODI), amount of compression at one or two levels and presence of edema on MRI or bone scan. Among the exclusion criteria are greater than 70% collapse, canal compromise and neurologic deficit at the level (s) to be treated. Patients must complete the VAS, ODI and SF-12 assessments as well as the informed consent. CT, MRI or bone scan and radiographs are obtained pre-operatively. Among the data collected during the procedure are the volume injected and patient vital signs.

Post-operative CT and radiographs are used to assess and quantify leakage. Patient evaluations (VAS, ODI, SF-12, Neurologic exam and Patient Satisfaction) are being conducted at the following time points; post-operatively (VAS and neurologic only), 72 hours (VAS only), 1 week (VAS, ODI and nuerologic only), 1 month, 3 months, 6 months, 12 months and 24 months. Radiographic evaluations are also being obtained at the same time points except at 72 hours.

Cortoss is injected using the Aliquot delivery system which allows for precision placement and control of material delivery. Cortoss has the advantage of infinite working time due to the 'mix-on-demand' delivery system. This allows the clinician to employ a 'start-stop' technique; that is, if a leak or posterior material migration is observed, then the injection process is stopped, the material allowed to harden and the mixing-injection process is repeated. In this way, the clinician can create dams to block material flow to undesirable locations.

Control patients were treated with commercially available PMMA which was mixed and injected using standard techniques and instrumentation.

Results

To date, 19 patients have been enrolled at this site; 9 treatment and 10 control. There were a total of 5 males and 14 females. A total of 23 levels have been treated; 12 in the treatment group and 11 in the control group. The average age is 80 in the treatment group (range 69 to 85) and 76 in the control group (range 58 to 88).

Treatment patients VAS improved from 78 (range 57 to 93) pre-op to 52 (range 10-100) at 72 hours, 48 (range 5 to 99) at 1 week and 33 (range 0-64) at 1 month.

Control patients' VAS improved from 81 (range 54 to 100) pre-op to 42 (range 8-100) at 72 hours, 34 (range 2 to 76) at 1 week and 29 (20-49) at 1 month.

Treatment patients' ODI improved from 54 (range 42 to 68) pre-op to 37 (range 6 to55) at 1 week and 33 (range 0 to 70) at 1 month.

Control patients ODI improved from 64 (range 56 to 73) pre-op to 39 (range 27 to 60) at 1 week and 37 (range 22 to 64) at 1 month.

The average volume of material injected in the treatment group was 1.9cc (range 1.0-2.7) and 3.4cc (range 1.0-7.5) in the control group.

Leakages were observed on post-op CT scans and found to be similar in both groups. All extravasations were asymptomatic with no cardiac irregularities or pulmonary emboli.

Conclusion

These preliminary results suggest that Cortoss provides similar pain relief compared to PMMA. These results are consistant with those obtained in the prospective vertebroplasty study using Cortoss conducted in Europe(1). The results also suggest that pain relief can be achieved using a smaller volume of Cortoss compared to the volume used for PMMA. This is due to the distinct interdigitated fill pattern obtained with Cortoss. These results in combination with favorable biomechanical properties, lack of fibrous tissue response as seen with PMMA(2), the precision delivery system and the 'start-stop technique' make Cortoss an attractive alternative to PMMA for use in vertebroplasty. As more data become available, we will continue to report the results on this exciting new biomaterial.

References

1. Palussiere J, Berge J, Gangi A, Cotton A, Pasco A, Bertagnoli R, Jackshe H, Carpeggiani P, Deramond H, Clinical Results of an Open Prospective Study of a bis-GMA Composite in Percutaneous Vertebral Augmentation, European Spine Journal, 2005.
2. Erbe, E., Clineff, T., Gualtieri, G., 'Comparison of a new bisphenol-a-glycidyl dimethacrylate-based cortical bone void filler with polymethyl methacrylate' Eur Spine J (2001) 10:S147-S152.

Disclosure - consultant for Orthovita

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