Article
Babinsky reflex was positive on both sides and abnormal bladder and bowel function were reported.
The initial supine radiographs showed
a slight junctional kyphosis but no indica- tions of vertebral fracture. CT scan (Fig- ure 3) and MRI (Figure 4) demonstrated a collapse and wedging of the T10 verte- bral body and a distraction pattern injury at the upper edge of the screw in the T10 pedicles, rupture of the posterior elements at T9-T10 with a high signal intensity con- sistent with hemorrhage and edema and subluxation at the cranial level. Abnormal intracanal tissue was noted compressing the spinal cord. With the confirmation of a T10 verte- bral compression fracture with sublux- ation of the adjacent level and neurologi- cal impairment, the authors performed posterior decompression at T9-T10 and extended posterolateral arthrodesis (Fig- ure 5) from T2 to T10 using bilateral pe- dicular screws augmented with cement at T2,T3,T4,T5 and T6, and non-cemented screws at T8 (Expedium-Confidence Spi- nal Cement System, DePuy Spine, Rayn- ham, MA, USA). Samples of the intracanal tissue were obtained for histological study, which reported a ring of fibrous and vas- cular tissue compatible with soft fracture repairing callus.
The patient had prompt improvement in back pain and was mobilised routinely. At 3 months follow-up, she was able to walk without pain and the neurological explora- tion was normal.
Conclusions A number of previous studies have report- ed perioperative and postoperative com- plication rates in adult spinal deformity surgery of up to or more than 40%7
. One
major complication is a compression frac- ture of the last instrumented and/or the su- pra-adjacent vertebral body7
, this requires
reintervention and extension of spinal fu- sion.
Augmentation of pedicle screws with
PMMA or calcium phosphate cement has been shown to improve the initial fixation and fatigue strength of instrumentation in osteoporotic vertebrae, and it also decreas- es the likelihood of compression fracture at the same level8
. Additional vertebroplasty of the neighboring 1 to 2 uninstrumented
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levels has been applied attempting to avoid the junctional kyphosis and compression fractures of cranial vertebrae. As mentioned before, Watanabe et al.6 described two patterns of proximal verte- bral fracture following spinal deformity surgery in adults receiving segmental pedicle screw instrumentation: upper in- strumented vertebral collapse + adjacent vertebral subluxation and supra-adjacent vertebral fracture alone. In an attempt to avoid these complications in our patient, we augmented the upper instrumented ver- tebra and its adjacent level, but this cre- ated excessive distractive stress in the pos- terior element, resulting in a compression fracture of the upper instrumented verte- bral body (even after being augmented with cement) with distraction of posterior elements and pedicles through the upper
edge of the screw and subluxation of the adjacent level. We hypothesise that vertebral augmen- tation could increase the risk of this com- plicated fracture. There are several factors that might lead to this complication: Incomplete cement filling of the ver- tebra can create an area of weakness be- tween two cemented areas (from the edge of the upper screws and the cranially-adja- cent cemented vertebra) that behaves like an osteoporotic vertebra between two ce- mented vertebras.
The insertion of the pedicular screw leads to pedicle weakness.
Ending the instrumentation construct just below the apex of the postoperative thoracic kyphosis is too-frequently associ- ated with junctional kyphosis/fractures9-11 The case presented here is concerning.
.
European Orthopaedic July 2012
Presenting the X-Act ROM range:
Post-op bracing for knee, elbow and hip.
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Autumn 2012 | SpinalSurgeryNews | 33
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