COMPARISON OF CLINICAL OUTCOME, INTERDIGITATION AND CEMENT LEAKAGE BETWEEN USAGE OF LOW AND MEDIUM VISCOSITY PMMA BONE CEMENT IN PERCUTANEOUS VERTEBROPLASTY

Abstract

Study Design: Comparative, prospective follow-up study.

Objective: Comparison of outcome between patients treated with Percutaneous VertebroPlasty (PVP) using low viscosity PolyMethylMetAcrylate (PMMA) bone cement and patients treated with PVP using medium viscosity PMMA bone cement. Summary of background data. Viscosity is the characterizing parameter of PMMA bone cement, currently the standard augmentation material in PVP, and influences interdigitation and cement distribution inside the vertebral body, injected volume and extravasation, thereby affecting the clinical outcome of PVP. In PVP, low, medium and high viscosity PMMA bone cements are used interchangeably. However, effect of viscosity of cement on clinical outcome in patients with Osteoporotic Vertebral Compression Fractures (OVCFs) has not yet been explicit subject of investigation.

Methods: Follow-up was conducted using a 0–10 Pain Intensity Numerical Rating Scale (PI-NRS) and the Short Form 36 (SF-36) Quality of Life (QoL) questionnaire before PVP and at 7 days (PI-NRS only), 1 month, 3 months and 12 months after PVP. Cement leakage was analyzed on direct post-operative CT-scanning. Injected cement volume was measured using a calibrated DICOM-viewer and the degree of interdigitation was assessed. At six and 52 weeks and at suspicion, patients were analyzed for the incidence of new fractures.

Results: Thirty consecutive patients received PVP using low viscosity PMMA bone cement (OsteoPal-V^®) for 62 OVCFs, followed by 34 patients who received PVP using medium viscosity PMMA bone cement (Disc-O-Tech^®) for 67 OVCFs. Baseline characteristics were comparable between groups. Viscosity qualification was stated by the manufacturer. results regarding PI-NRS and SF-36 were comparable between both groups. Postoperative comparison of injected cement volume, degree of interdigitation, proportion of bipedicular procedures, incidence of new vertebral fractures and complications revealed no substantial differences between both groups. In the low viscosity group a significantly greater proportion of vertebrae showed cement extravastion (81,0% versus 71,6%, p = 0,029).

Multiple logistic analysis revealed no definitive predictive factors for the occurrence of cement leakage (yes/ no) (Odds Ratio [95% CI], P):

• Severity (acc to Genant et al): 1.82 [0,69 – 4.89], 0.229

• Fracture Type (Genant et al): 1.22 [0.64 – 2.32], 0.550

• Injected Volume: 0.98 [0.76 – 1.27], 0.875

• Spinal Region: 0.87 [0.48 – 1.55], 0.628

• Cement Viscosity: 0.42 [0.16 – 1.10], 0.076

Conclusion: No major differences in clinical outcome after PVP in OVCFs using low and medium viscosity PMMA bone cement were found. Viscosity of PMMA bone cement is likely to influence cement extravastion, although this could not be confirmed.