Re-expansion of Osteoporotic Compression Fractures Using Bilateral SpineJack Implants: Early Clinical Experience and Biomechanical Considerations

Abstract

Thoraco-lumbar osteoporotic compression fractures have a higher incidence of continued collapse with development of deformity and progression to vertebra plana when untreated and even after vertebral augmentation (VA) or balloon kyphoplasty (BKP). Even when there is the restoration of height and improvement in angulation, multiple long-term follow-up series have repeatedly documented that over time, many patients lose the initial height correction and in a smaller group the vertebral body re-collapses leading to the development of progressive deformity with an increased risk for adjacent level fractures. At first, larger balloons and more cement were used to try and avoid these problems, but it did not reduce the risk of adjacent fractures. Several procedures were developed to place various types of intervertebral implants combined with bone cement to maintain the initial height correction. Initial studies with these implants showed a reduction in adjacent level fractures but the systems did not proceed to market. The SpineJack R (SJ) system (Stryker Corp, Kalamazoo, MI), consisting of bilateral expandable titanium implants supplemented with bone cement, was first used approximately 10 years ago in Europe and recently gained FDA approval in the United States. This system provides more symmetric and balanced lateral and anterior support and is effective with lesser amounts of bone cement compared to BKP. Follow-up studies have documented that there is equal or better pain control, with better long-term results based both on maintaining vertebral height restoration and deformity correction. Most importantly, statistically it clearly reduces the risk of adjacent level fractures by at least 60%. The biomechanical effects of intravertebral implants for osteoporotic fractures in regard to the risk of adjacent level fractures and preliminary experience with the use of the SJ is reviewed.

Re-expansion and Stabilization of Vertebra Plana Fractures Using Bilateral SpineJack® Implants

“…In cases planning to use a SJ device, CT scan provides more accurate measurements of the pedicle width in axial view, which is used for sizing of the closed implant diameter and determining overall depth within the fractured vertebral body [ 7 , 8 , 13 ]. CT also gives detailed information in any fracture lines through the endplates and posterior vertebral wall that may be related to increased risk of cement leakage either into the disk space or epidural space [ 14 ].…”

“…Over the last 10 years, the evolution of third-generation intravertebral implants demonstrates that implants often can provide significant height correction beyond what occurs with balloon kyphoplasty and that this correction can be maintained over one or more years. Follow-up studies have also shown that these permanently expanded implants are associated with statistically less adjacent level fractures [ 7 , 8 ]. VP cases were specifically excluded from the early SpineJack® (SJ) studies (Stryker Corp, Kalamazoo, Michigan, USA) [ 7 ].…”

“…The SAKOS as well as several other subsequent studies confirmed these expandable implants not only created better initial height correction, especially in the anterior and middle part of the vertebrae, but its superiority was maintained in long-term follow-up up to one year with an additional finding of significantly less adjacent level fractures. The SAKOS study, however, specifically excluded VP patients that we address in this report [ 7 , 8 ].…”

Treatment of a High-risk Thoracolumbar Compression Fracture Using Bilateral Expandable Titanium SpineJack Implants

“…These titanium implants could also be used as a structural adjunct in treating fractures related to destructive vertebral tumors combined with radiation or intratumoral therapy. In a 36-month follow-up study comparing BKP to SJ, clinical improvements were observed with both procedures over the three-year period, vertebral height restoration/kyphotic correction was still evident at 36 months, with a greater mean correction of anterior (10 ± 13% vs 2 ± 8% for BKP, p = 0.007) and central height (10 ± 11% vs 3 ± 7% for BKP, p = 0.034) and a larger correction of the vertebral body angle (− 5.0° ± 5.1° vs 0.4° ± 3.4°; p = 0.003) for SJ group [16-18]. The initial correction is both maximized and maintained while using less PMMA, an average of 2.5 to 3.00 cc of cement in total, leading to less risk of cement leakage (Figure 5).…”

“…It has been shown that the previous PEEK implants restored pressure in the affected disc associated with vertebral endplate fracture and may be related to the significant lower incidence of adjacent level fractures seen in long term SJ studies [14-15]. More recent intra-operative pre and post SJ implant studies show restoration of the adjacent superior disc pressures closer to normal which correlates with a lower incidence of adjacent level fractures compared to BKP [13,17-18].…”