Treatment of an osteoporotic vertebral compression fracture with the StaXx FX system resulting in intrathoracic wafers: a serious complication
To report a serious complication of the StaXx FX system used to stabilize an osteoporotic vertebral fracture.
A 76-year-old woman presented with a painful vertebral fracture. Treatment by means of a PEEK wafer kyphoplasty was complicated by malposition of the wafers. The patient recovered fully after removal of the wafers by means of a thoracotomy.
New treatment modalities have their own pitfalls and possible complications, as demonstrated in this case report. Caution regarding implementation of new treatment modalities should be practiced.
The impact of osteoporotic vertebral compression fractures (VCF) on mortality  and quality of life  is increasingly acknowledged. Despite successful conservative treatment of the majority of patients , 37% of patients referred for an X-ray of the thoracic or lumbar spine by their general practitioner still experience pain after six months . Vertebroplasty (VP), originally developed for treatment of vertebral angiomas  and kyphoplasty (KP) are now commonly accepted treatment options for VCFs.
Potentially serious complications (cement leakage leading to pulmonary emboli or neurological deficit) of VP and KP have been reported [6–8]. An alternative KP procedure uses sequentially inserted 1-mm thick polyetheretherketone (PEEK) wafers for controlled and vertically oriented kyphosis correction (StaXx FX system, Spine Wave, Inc, Shelton, USA). The theoretical advantages over other VP and KP procedures are retained fracture reduction, less cement leakage and restoration of the load-bearing properties of the intervertebral disc .
Complications can occur with all surgical procedures, but especially when they are serious and occur while using a new device lacking clinical results publication is warranted. We present a case report of a PEEK wafer KP resulting in anterolateral perforation of the vertebral body, necessitating a thoracotomy.
The thoracic spine X-ray performed the following day confirmed malposition of the wafers. The patient remained in good general condition, and was discharged from the hospital. The patient was prescribed acetaminophen with codeine 500/20 mg 4 times 2 daily and tramadol 50 mg 3 times 1 daily (VAS 4).
We present a serious complication of a PEEK wafer KP procedure in an osteoporotic VCF. Fortunately, the patient recovered extremely well. In addition to investigating characteristics of bone substitutes to decrease complications of VP and KP [10–13], alternatives and modifications of VP and KP are currently emerging. These include lordoplasty , vesselplasty , vertebral body stenting , mesh-allograft-stenting , among others , as well as the StaXx FX system. In experimentally created VCFs, partial endplate reduction and kyphosis correction could be achieved with the StaXx FX system, with intervertebral disk pressure corrected to 86% of normal . In addition, in 26 VCFs treated with the device, a significant decrease in visual analogue scale (VAS) pain score was observed after 8 months of follow-up . No clinical reports comparing these alternatives of VP and KP to regular VP or KP or conservative treatment are available. Surgical treatment of VCFs unresponsive to conservative therapy (with VP or KP) remains controversial [20–29]. In a subgroup of patients, VP appears to be superior to conservative treatment . Unfortunately, at the moment it is not possible to identify these patients shortly after they sustain a VCF.
Perforation of the vertebral cortex with the wafer gun, creating a hole through which the wafers could protrude (faulty surgical technique). Perhaps at this moment switching to another method of stabilisation (for instance posterior instrumentation) would have been preferred. A more gradual increase in diameter of the wafer gun possibly lowers resistance during insertion, which might reduce occurrence of this complication.
A design flaw in the wafer gun allowing the wafers to progress beyond its anterior rim. Perhaps a higher anterior rim or different wafer shape would prevent this.
Incidence and prevalence of osteoporotic VCFs will increase. Heightened awareness of their impact on quality of life and mortality is changing our view of these fractures. Patients today are better informed and more assertive, in demanding (surgical) treatment. Nevertheless, we need to remain critical of new treatment modalities while their (long-term) results and complications are unknown. We feel it is important to describe complications occurring while using (new) surgical systems.
We would like to thank Mr. S. Westerbos, MD for his valuable contribution to this article. No funds or benefits have been or will be received for this manuscript.
Conflict of interest
None of the authors has any potential conflict of interest.
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