Introduction: Traumatic vertebral compression fractures (VCF) should be distinguished from fragility fractures, occurring as a result of decreased bone strength due to osteoporosis or cancer.
Polymethylmethacrylate cement (PMMA), as standard in fragility fractures, does not have the capacity to undergo remodeling. Therefore in young patients, a bio-compatible/–resorbable alternative would be preferable. KyphOs FS(R), a calcium magnesium hydroxyapatite cement has been developed for use during Balloon Kyphoplasty (BKP), a minimal invasive therapy.
This single-arm multicenter study evaluates the safety and effectiveness of this cement during BKP in young patients with stable VCFs.
We describe the clinical results up to 3mo of the ongoing 1-year follow-up study.
Methods: Male and female patients, aged 50 years or less, with up to 3 VCFs of type A1.1, A1.2 or A3.1, according to the Magerl/AO classification were included. The primary endpoint was the change from baseline in the 24 point Roland Morris Disability Questionnaire (RMDQ) score at seven days. Secondary endpoints included the quality of life as measured by EuroQol-5 Domain questionnaire (EQ-5D), the 10 point self-rated back pain (VAS) and device and/or procedure related adverse events.
Based on the standard deviation in the Wood study, up to 100 patients had to be enrolled to detect the minimal clinical important difference (MCID) of 2–3 pts on the primary endpoint.
Results: 50 patients out of 51 enrolled were eligible. The mean age was 36.4 years, 64% were male. 80% of the patients were treated for 1 VCF, 14% for 2 VCFs and 6% for 3 VCFs. At 3 mo, data of 45 patients were available. Mean RMDQ score at baseline was 20.29pts. The change from baseline in RMDQ at 7d was 9.42pts(95%CI 7.50–11.34, p<
0.0001) and 16.76pts(95%CI 15.21–18.30,p<
0.0001) at 3mo. Mean EQ-5D score at baseline was 0.16pts. The change from baseline in total EQ-5D at 7d was 0.52pts(95%CI 0.42–0.62,p<
0.0001) and 0.71pts(95%CI: 0.60–0.82,p<
0.0001) at 3mo. The change from baseline in VAS at 7d was 4.44pts(95%CI 3.80–5.08,p<
0.0001) and 5.43pts(95%CI 4.81–6.05,p<
0.0001) at 3mo. There were no device-related serious adverse events during the peri-operative period up to 3 mo.
Discussion: The MCID on the RMDQ is 2–3pts. In this study we obtained a difference of 9.42 points at 7 days. The recruitment was terminated earlier because of the highly significant results. The results on RMDQ were confirmed on all the other secondary endpoints with further improvement up to 3 mo.
Conclusion: The use of KyphOs FS(R) during BKP, appears to be a safe and effective method to treat traumatic VCFs in young patients. Longer follow-up is needed to confirm the results at 1 year.
