To the editor:
Sir, we read with great interest the article published by Hwang KT et al. [1] which compared the outcomes of balloon kyphoplasty (KP) performed to treat osteoporotic vertebral compression fracture (OVCF) in rheumatoid arthritis (RA) patients with the outcomes in non-RA patients. It was an interesting and novel study in which the author suggested that the use of KP to treat OVCF in RA group exhibited similar outcomes to non-RA group in terms of pain reduction, vertebral height restoration, and kyphosis correction. However, RA group had significantly higher rate of complications involving adjacent segment fracture and recollapse. However, we have certain concerns regarding the methodology and results which need to be addressed before meaningful conclusions can be drawn from the study.
Association of OVCF with neurological deficit is rare, but, well documented in the literature. Gradual onset neurological deficit which necessitated the decompression of spinal cord and stabilization is also reported [2, 3]. In the present study, information about OVCF with neurological deficit is not available. Since this would have affected the functional outcome, it would be pertinent to know if patients with neurological deficit were included or excluded from study.
5 (22%) patients were not receiving methotrexate in the RA group. It would be more informative to know the status of other disease modifying antirheumatic drugs as biological/targeted synthetic disease modifying antirheumatic drugs (b/tsDMARD) have protective effects on bone mineral density (BMD) whereas conventional synthetic DMARD (csDMARD) decrease the BMD [4].
Information about the medical management after kyphoplasty in RA group and non-RA group would have been informative. As in osteoporotic fractures, treatment with anti-osteoporotic therapy (teriparatide, bisphosphonates, calcitonin and raloxifen) reduces the incidence of adjacent vertebral fractures, recollapse and new vertebral fracture after kyphoplasty [5, 6]. If patients in either group received anti-osteoporotic therapy then comparison of complication rates would give erroneous results.
There appears to be typographical error in the result section, Table 1 (demographic data) and Table 4 (post-operative complications) which needs clarification.
According to the result section and Table 4—recollapse occurred in six patients (19.3%) in the RA group and in five patients (4.0%) in the non-RA group, whereas since recollapse was noted in six of 23 patients it should read as 26% in RA, 5 out of 107 patients as 4.67% in the non-RA group.
According to the result section and Table 4—adjacent segment fracture occurred in three patients (9.6%) in RA group and in six patients (4.8%) in the non-RA group, whereas since it was three of 23 patients (13.04%) in RA group and 6 out of 107 patients (5.60%) in the non-RA group.
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The authors declare that they have no conflict of interest.
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This article does not contain any studies with human or animal subjects performed by the any of the authors.
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References
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