Suitability of a calcium phosphate cement in osteoporotic vertebral body fracture augmentation: a controlled, randomized, clinical trial of balloon kyphoplasty comparing calcium phosphate versus polymethylmethacrylate.

STUDY

DESIGN

A prospective randomized controlled clinical study.

OBJECTIVE

To investigate the feasibility of a calcium phosphate cement (CaP) in balloon kyphoplasty if compared to polymethylmethacrylate (PMMA).

SUMMARY OF BACKGROUND DATA: In kyphoplasty and vertebroplasty, PMMA currently represents the standard in augmentation materials. It is characterized, however, by a lack of osseointegration and limited biocompatibility. Consequently, CaP is currently being investigated as an alternative material for vertebral augmentation.

METHODS

Inclusion criteria were 1 or 2 adjacent osteoporotic fractures of vertebral bodies in the thoracolumbar spine, patient age > or =65 years, and fracture age < or =4 months. Exclusion criteria were tumor lesions and additional posterior instrumentation.

RESULTS

A total of 60 osteoporotic vertebral body fractures in 56 patients were included. CaP and PMMA were randomly applied in 30 vertebrae each with 2-fracture-patients receiving only 1 type of cement for both vertebrae. All 60 fractures were classified compression fractures (type A). Of these, 27 were classified burst fractures (type A3). 52/56 patients experienced statistically significant pain relief (7.9 +/- 1.9 to 1.8 +/- 2.1 on a Visual Analog Scale from 0 "best" to 10 "worst"). Bisegmental endplate angles were restored by 6.2 degrees +/- 5.9 degrees on average. Complications that turned out to be cement-specific were: vascular embolism (n = 2) for PMMA; subtotal cement washout (n = 1); and radiographic loss of correction (n = 9) due to cement failure in burst fractures for CaP. There was no case of cement failure, when PMMA had been used.

CONCLUSION

The routine use of the CaP tested is not currently recommended for kyphoplasty. Because of its low resistance against flexural, tractive, and shear forces compared to PMMA, in certain constellations (burst fractures), there is a higher risk of cement failure and subsequent loss of correction.