Elsevier

The Spine Journal

Volume 17, Issue 8, August 2017, Pages 1192-1199
The Spine Journal

Technical Report
Potential risks of using cement-augmented screws for spinal fusion in patients with low bone quality

https://doi.org/10.1016/j.spinee.2017.04.029Get rights and content

Abstract

Background Context

Dramatic increases in the average life expectancy have led to increases in the variety of degenerative changes and deformities observed in the aging spine. The elderly population can present challenges for spine surgeons, not only because of increased comorbidities, but also because of the quality of their bones. Pedicle screws are the implants used most commonly in spinal surgery for fixation, but their efficacy depends directly on bone quality. Although polymethyl methacrylate (PMMA)-augmented screws represent an alternative for patients with osteoporotic vertebrae, their use has raised some concerns because of the possible association between cement leakages (CLs) and other morbidities.

Purpose

To analyze potential complications related to the use of cement-augmented screws for spinal fusion and to investigate the effectiveness of using these screws in the treatment of patients with low bone quality.

Study Design

A retrospective single-center study.

Patient Sample

This study included 313 consecutive patients who underwent spinal fusion using a total of 1,780 cement-augmented screws.

Methods and Outcome Measures

We analyzed potential complications related to the use of cement-augmented screws, including CL, vascular injury, infection, screw extraction problems, revision surgery, and instrument failure. There are no financial conflicts of interest to report.

Results

A total of 1,043 vertebrae were instrumented. Cement leakage was observed in 650 vertebrae (62.3%). There were no major clinical complications related to CL, but two patients (0.6%) had radicular pain related to CL at the S1 foramina. Of the 13 patients (4.1%) who developed deep infections requiring surgical debridement, two with chronic infections had possible spondylitis that required instrument removal. All patients responded well to antibiotic therapy. Revision surgery was performed in 56 patients (17.9%), most of whom had long construction. A total of 180 screws were removed as a result of revision. There were no problems with screw extraction.

Conclusions

These results demonstrate the efficacy and safety of cement-augmented screws for the treatment of patients with low bone mineral density.

Introduction

As the population ages, spine surgeons are seeing an increasing number of cases with a wide variety of degenerative changes of the lumbar spine that require instrumented spinal fusion [1], [2], [3]. Surgical management in the elderly population presents some challenges. Pedicle screws that can provide three-column fixation are the most common implants used in spinal surgery, but screw performance depends on bone quality [4], [5], [6]. Accordingly, patients with osteoporosis may be predisposed to higher failure rates following posterior internal fixation system failure. Screw-loosening tests performed on patients that vary in terms of their bone quality has demonstrated that good-quality trabecular bone enhances solid fixation, whereas osteoporotic bone has a higher risk of implant failure [7], [8].

Several pedicle screw fixation techniques have been developed to improve anchoring strength and to decrease the risk of loosening [9], [10], [11], [12], but polymethyl methacrylate (PMMA)-augmented screws have been shown to be the most efficient system for strengthening pedicle screws and achieving stable fixation [13], [14], [15], [16], [17]. However, their use has raised concerns because of potential associated morbidities, such as nerve injury or vascular damage, which could be caused by cement leakage (CL). To our knowledge, no clinical studies have analyzed these potential complications. The purpose of this work was to assess the risk factors associated with the use of cement-augmented screws in spinal fusion in patients with osteoporotic vertebrae.

Section snippets

Study design

This was a retrospective study that evaluated the clinical results of surgical treatment with PMMA-augmented pedicle screws in patients with poor bone quality and various spinal diseases. A total of 313 consecutive patients (247 women, 66 men) were studied. The mean age was 73.6±7.2 years (range: 40.4–90 years), and the mean follow-up time was 29.68±14.9 months (range: 12–77 months). The patients had the following conditions: degenerative disease (223 patients), deformity (32 patients),

Results

A total of 1,043 vertebrae were instrumented with 1,780 cemented screws in 313 patients. Most of the augmented screws (84.1%) were placed at the lumbar and thoracolumbar spine, and only 42 (4%) were placed at the thoracic spine (T1–T9) (Fig. 1). The average cement volume injected per screw was 2.36 cc. Cement leakage was analyzed by radiography and by postoperative CT scans and was classified as epidural, foraminal, intradiscal, venous paravertebral, canal, or extravertebral (including

Discussion

The general population is living longer, and spine surgeons are increasingly dealing with elderly patients. Pedicle screws have been shown to be the best way to achieve fixation in the lumbar spine, but their use is controversial in patients with osteoporosis or fragile bone, because pull-out strength and fatigue failure are linearly related to BMD [7], [8]. Several techniques have been developed to ensure the attachment of screws to the fragile bone. The use of expandable screws [18], [19] has

Conclusion

Our group previously demonstrated the clinical effectiveness of using PMMA pedicle-augmented screws for the surgical treatment of patients with lumbar instability [26]. Here, in a larger series of patients, we demonstrated the safety of this technique. Our data indicate that this procedure is a good clinical choice for the surgical treatment of patients with low bone quality.

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      Fenestrated screws were used in all except seven studies. Except for nine studies [11,13,14,20–22,24,25,27], all studies reported data on dual-energy X-ray absorptiometry (DEXA) scores which were < −2.5 for all included patients. The sample size of the studies varied from 15 to 313 patients.

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    FDA device/drug status: approved (Cement-Augmented Screws).

    Author disclosures: MM-F: Nothing to disclose. AL-H: Nothing to disclose. ARP: Nothing to disclose. FT-B: Nothing to disclose. JMD: Nothing to disclose. MDV: Nothing to disclose. MGR-A: Nothing to disclose. LA-G: Consulting fee or honorarium: Zimmer Biomet (B, Paid directly to institution/employer), pertaining to the submitted work; Speaking and/or Teaching Arrangements: Spineart (B, Paid directly to institution/employer), outside the submitted work.

    The disclosure key can be found on the Table of Contents and at www.TheSpineJournalOnline.com.

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