European spine journal : official publication of the European Spine Society, the European Spinal Deformity Society, and the European Section of the Cervical Spine Research Society
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Comparative Study
A two-cage reconstruction versus a single mega-cage reconstruction for lumbar interbody fusion: an experimental comparison.
Interbody cages are used as an adjunct to anterior lumbar interbody fusion, but exposure and insertion of two cages can be difficult. A biomechanical study was performed to compare the stability and exposed surface for fusion obtained with interbody reconstruction using two traditional cylindrical cages (18-mm diameter) vs. a single expanded mega-cage (24-mm diameter). A single-cage technique could result in safer exposure, shorter operating time, and less cost. ⋯ The stiffness with a single anterior mega-cage was significantly lower in flexion compared with two standard cages. However, in all other modes of testing the constructs were statistically equivalent, although neither construct was significantly stiffer than the intact specimen. Additionally, the single mega-cage provides an equivalent cancellous bed for fusion as compared to dual cages. While this study is not sufficient to recommend human application, these results and our previous experience with the successful in vivo use of a single cage in rhesus monkeys [4] suggest that the single expanded anterior cage may be an acceptable concept although subsidence risk needs further investigation. The potential advantages of a single mega-cage (safer for the foramen, safer for the vessels, more consistent decortication and possibly cheaper) further suggest that examination should be given to this method as an approach to anterior interbody reconstruction in selected patients.
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A 13-year-old male achondroplastic dwarf with fixed thoracolumbar kyphosis was treated by segmental pedicle screw fixation, posterolateral fusion combined with one stage two level posterior column resection. Preoperative and postoperative kyphosis angles were 97 and 32 degrees, respectively. Combination of segmental pedicle instrumentation with posterior column resection is a treatment option even in immature achondroplastic patients.
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To date, only three cases of artificial disc prosthesis dislocation have been reported in the literature. We present in detail two additional cases of prosthesis dislocation and discuss the surgical interventions undertaken that resulted in a good clinical outcome in both patients.