Background: Polymethyl methacrylate (PMMA) bone cement is widely used for osteoplasty.
However, previous studies have demonstrated the adverse effects of PMMA due to its excessive
stiffness and heat production. Recently, calcium phosphate cement (CPC) that overcomes those
negative effects has been successfully applied in osteoplasty. The potential problem of CPC is
markedly less initial stiffness. It leads to progressive, repeated collapse in the treated vertebra
before CPC has been replaced by new bone that would provide substantial improvement in
compressive strength and stiffness. The activated platelets in platelet-rich plasma (PRP) release a
high concentration of growth factors which play an important role in bone healing.
Objective: To investigate whether PRP could accelerate the osteoconduction of CPC and enhance
the bone strength of the treated vertebra in an animal model.
Study Design: Controlled animal study.
Setting: Laboratory animal study,
Methods: Thirty-two female Sprague-Dawley rats were ovariectomized at 8 weeks of age. After 3
months, they were randomly divided into 4 groups and received cement augmentation in the fifth
caudal spine with different filler materials; sham-operated rats (S), PMMA (P), CPC (C), and CPC +
PRP (CP). Bone mineral density (BMD) and trabecular type-associated morphological parameters,
including trabecular bone volume fraction and trabecular thickness in the augmented caudal spine,
were evaluated by micro-computed tomography (mirco-CT) 2 weeks after the cementoplasty.
Histological analysis was also performed to compare the bone regeneration.
Results: The trabecular bone volume fraction in the CP group was significantly greater than those
of all the other groups. Trabecular thickness was higher in the CP group than the S and P groups.
This augmented trabecular structure in the CP group accordingly showed higher BMD. Histological
evaluations showed significantly more bone regeneration in the CP group.
Limitations: There has been a concern that the effect of PRP would be dependent on the
species, and might show different results in humans. Baseline values of micro-CT analysis were
not measured, which could have provided exact evidence of the changes in trabecular microarchitecture parameters and cement resorption profiles. Finally, caudal vertebrae with filler
materials used in biological study should have been compared by their mechanical properties using
biomechanical evaluations for a more coherent study, which was not possible due to technical
problems.
Conclusions: Incorporating PRP into CPC could accelerate osteoconduction in the augmented
vertebra leading to improvement of trabecular bone microarchitecture and BMD in rats.
Key words: Bone mineral density, calcium phosphates, cementoplasty, histology, osteoconduction,
osteoporosis, platelet-rich plasma, polymethyl methacrylate, vertebra
Trabecular Bone Assessment Using Magnetic-Resonance Imaging: A Pilot Study
