How is surgical treatment of kyphosis performed?

Updated: May 04, 2020
  • Author: R Carter Cassidy, MD; Chief Editor: Jeffrey A Goldstein, MD  more...
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The spinal cord and its roots are at risk during correction of kyphosis, especially when the canal is stenotic or when the cord is tethered at the apex of the kyphosis. In these situations, consideration should be given to performing anterior decompression before the posterior arthrodesis. The cord is also at risk for ischemia if blood flow is altered with the change in spinal alignment. [11]

Manipulation of the spinal cord, especially during osteotomies in the thoracic spine, should be avoided. Evidence suggests that the lower lumbar roots are vulnerable during pedicle-subtraction osteotomy, more so than the upper lumbar roots are. [46]  Careful attention should be paid to the removal of posterior bone and ligament, which may buckle into the canal as the osteotomy is closed.

Thorough central decompression is recommended to help prevent neurologic compromise. Subluxation of the spine can also occur when an osteotomy is being closed; therefore, intraoperative radiography is essential to facilitate rapid identification and correction of subluxation.

Neural monitoring may help identify correctable neurologic injury before the case is concluded. Monitoring of somatosensory and motor evoked potentials can be helpful in detecting reversible neural injury (eg, from stretching during correction of deformity or improper placement of devices). However, neural monitoring may not be useful with isolated root injuries. [20, 21]  A wake-up test can also be performed to assess the patient's gross motor function after the deformity is corrected.

Blood loss can be clinically significant during correction of kyphosis, especially if anterior procedures and large osteotomies are being performed. [61]  Bleeding should be controlled at every step of the operation to keep overall loss to a minimum. Clinically significant blood loss can cause hypotension and potentially injure the spinal cord, myocardium, or retina. Intraoperative blood-loss mitigation techniques include preoperative autodonation, decreasing abdominal pressure, and use of antifibrinolytic drugs. [62, 63, 64]

In terms of intraoperative considerations related to instrumentation, it is important to ensure that the substantial cantilever force applied to the spine with posterior instrumentation is spread over multiple levels. In the thoracic spine, sublaminar wires, hooks, or screws can be used. Pedicle screws in multiple sites will spread the force throughout the construct. Pedicle screws are also useful with aggressive osteotomies, which tend to destabilize the spine. Segmental fixation increases the surgeon's control over the coronal plane, where a deformity can coexist with a sagittal deformity. [10, 65, 66]

In the lumbar spine, pedicle screws are most often used for the reasons just mentioned. Osteoporosis should be addressed with multiple points of posterior fixation, and a low threshold should be maintained for performing concomitant anterior fusion. This approach may help prevent implant pull-out or postoperative collapse and loss of correction.

Intervertebral instrumentation can be useful in increasing the fusion rate and improving deformity correction. Numerous procedures exist for placing an interbody spacer, often filled with osteoconductive matrix, into the spine. These spacers can be placed from the back (transforaminal lumbar interbody fusion, posterior lumbar interbody fusion), from the side (extreme lateral interbody fusion, oblique lumbar interbody fusion), or from the front (anterior lumbar interbody fusion). 

Aggressive correction of the spine can be achieved with vertebral-column resection. In a review of adult and pediatric patients with severe deformities who underwent a vertebral-column resection, the correction at final follow-up was in the range of 53-61%, and improvements were noted on patient-reported outcome measures, despite a 56% complication rate. [53]

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