Sung Bae Park, Tae-Ahn Jahng, Chi Heon Kim, and Chun Kee Chung
The aim of this study was to describe a novel technique for laminoplasty in which translaminar screws are used in the thoracic and lumbar spine.
The authors first performed a morphometric study in 20 control individuals using 3D reconstructed CT scans and spine simulation software to measure the lengths and diameters of the spaces available for translaminar screw placement from the T-1 to S-1.
Based on the results of the morphometric study, the authors then attempted translaminar screw fixation in 5 patients (April 2007–July 2007) after en bloc laminectomy in the thoracic and lumbar regions. All patients had intradural lesions: 3 schwannomas, 1 cavernoma, and 1 arachnoid cyst.
The morphometric study in control individuals revealed that the safe trajectories for simulated screws measured 25–30 mm in length and 8–11 mm in diameter in the thoracic region (T1–12) and 26–34 mm in length and 6–7 mm in diameter in the lumbosacral region (L1–S1). This morphometric and simulation study showed that translaminar screw placement would be possible in practice.
Five patients underwent en bloc laminoplasty and translaminar screw fixation in which the screws measured 2.7 mm in diameter and 24 or 26 mm in length. Sixteen attempts at translaminar fixation were made in 8 vertebrae. Fourteen translaminar screws were successfully placed at the thoracic and lumbar levels. Two microplates had to be used because the laminae were too thin and narrow after further laminectomy with undercutting. There were no complications associated with the translaminar screws.
The mean follow-up period was 14.5 months. There was no screw breakage or displacement. Solid osseous fusion was documented in 2 patients who underwent CT scanning 15 months postoperatively.
The authors found that the laminoplasty and translaminar screw technique is feasible in the thoracic and lumbar regions, but further studies are needed to analyze the biomechanical effects and long-term outcomes in a large number of patients.
Chang-Hyun Lee, Tae-Ahn Jahng, Seung-Jae Hyun, Chi Heon Kim, Sung-Bae Park, Ki-Jeong Kim, Chun Kee Chung, Hyun-Jib Kim, and Soo-Eon Lee
The Dynesys, a pedicle-based dynamic stabilization (PDS) system, was introduced to overcome the drawbacks of fusion procedures. Nevertheless, the theoretical advantages of PDS over fusion have not been clearly confirmed. The aim of this study was to compare clinical and radiological outcomes of patients who underwent PDS using the Dynesys system with those who underwent posterior lumbar interbody fusion (PLIF).
The authors searched PubMed, Embase, Web of Science, and the Cochrane Database. Studies that reported outcomes of patients who underwent PDS or PLIF for the treatment of degenerative lumbar spinal disease were included. The primary efficacy end points were perioperative outcomes. The secondary efficacy end points were changes in the Oswestry Disability Index (ODI) and back and leg pain visual analog scale (VAS) scores and in range of motion (ROM) at the treated and adjacent segments. A meta-analysis was performed to calculate weighted mean differences (WMDs), 95% confidence intervals, Q statistics, and I2 values. Forest plots were constructed for each analysis group.
Of the 274 retrieved articles, 7 (which involved 506 participants [Dynesys, 250; PLIF, 256]) met the inclusion criteria. The Dynesys group showed a competitive advantage in mean surgery duration (20.73 minutes, 95% CI 8.76–32.70 minutes), blood loss (81.87 ml, 95% CI 45.11–118.63 ml), and length of hospital stay (1.32 days, 95% CI 0.23–2.41 days). Both the Dynesys and PLIF groups experienced improved ODI and VAS scores after 2 years of follow-up. Regarding the ODI and VAS scores, no statistically significant difference was noted according to surgical procedure (ODI: WMD 0.12, 95% CI −3.48 to 3.72; back pain VAS score: WMD −0.15; 95% CI −0.56 to 0.26; leg pain VAS score: WMD −0.07; 95% CI −0.47 to 0.32). The mean ROM at the adjacent segment increased in both groups, and there was no substantial difference between them (WMD 1.13; 95% CI −0.33 to 2.59). Although the United States is the biggest market for Dynesys, no eligible study from the United States was found, and 4 of 8 enrolled studies were performed in China. The results must be interpreted with caution because of publication bias. During Dynesys implantation, surgeons have to decide the length of the spacer and cord pretension. These values are debatable and can vary according to the surgeon's experience and the patient's condition. Differences between the surgical procedures were not considered in this study.
Fusion still remains the method of choice for advanced degeneration and gross instability. However, spinal degenerative disease with or without Grade I spondylolisthesis, particularly in patients who require a quicker recovery, will likely constitute the main indication for PDS using the Dynesys system.
Chang-Hyun Lee, Young II Won, Young San Ko, Seung Heon Yang, Chi Heon Kim, Sung Bae Park, and Chun Kee Chung
Combined anterior-posterior (AP) surgery is considered the gold standard for surgical treatment of Scheuermann kyphosis. There are trends toward posterior-only (PO) surgery for correcting this deformity because of the availability of multisegmental compression instruments and posterior shortening osteotomy. To date, surgical strategies for Scheuermann kyphosis remain controversial. The purpose of this study was to compare various surgical approaches for the treatment of Scheuermann kyphosis, including radiological correction and intraoperative outcomes, using a systematic review and meta-analysis.
A comprehensive database search of PubMed, EMBASE, Web of Science, and Cochrane Library was performed to identify studies concerning Scheuermann kyphosis. The inclusion criteria were direct comparisons between AP and PO surgeries for Scheuermann kyphosis and assessment of the angle of thoracic kyphosis preoperatively and postoperatively. The authors used the principles of a cumulative meta-analysis by updating the pooled estimate of the treatment effect.
Data from 13 studies involving 1147 participants (542 patients in the AP group and 605 patients in the PO group) were included. The average age was 18.2 years for the AP and 17.9 years for the PO group. The overall mean difference of changes in thoracic kyphosis angles between the AP and PO surgeries was 0.23° (95% CI −2.24° to 2.71°). In studies in which posterior shortening osteotomies were not performed, PO surgery resulted in a significantly low degree of correction of thoracic kyphosis, with a mean difference of 5.59° (95% CI 0.34°–10.83°). Studies in which osteotomies were performed revealed that the angle of correction for PO surgery was comparable to that of AP surgery. Regardless of fixation methods, PO surgical approaches achieved comparable angles.
PO surgery using posterior osteotomies can achieve correction of Scheuermann kyphosis as successfully as AP surgery does. Reflecting the advancement of surgical technology, large prospective studies are necessary to identify the proper treatments for Scheuermann kyphosis.
So-Hyang Im, Moon Hee Han, Bae Ju Kwon, Jung Yong Ahn, Cheolkyu Jung, Sung-Hye Park, Chang Wan Oh, and Dae Hee Han
Considerable confusion exists in the literature regarding the classification of cerebrovascular malformations and their clinical significance. One example is provided by the atypical developmental venous anomaly (DVA) with arteriovenous shunt, because it remains controversial whether these lesions should be classified as DVAs or as atypical cases of other subtypes of cerebrovascular malformations. The purpose of this study was to clarify the classification of these challenging vascular lesions in an effort to suggest an appropriate diagnosis and management strategy.
The authors present a series of 15 patients with intracranial vascular malformations that were angiographically classified as atypical DVAs with arteriovenous shunts. This type of vascular malformation shows a fine arterial blush without a distinct nidus and early filling of dilated medullary veins that drain these arterial components during the arterial phase on angiography. Those prominent medullary veins converge toward an enlarged main draining vein, which together form the caput medusae appearance of a typical DVA.
Based on clinical, angiographic, surgical, and histological findings, the authors propose classifying these vascular malformations as a subtype of an arteriovenous malformation (AVM), rather than as a variant of DVA or as a combined vascular malformation.
Correct recognition of this AVM subtype is required for its proper management, and its clinical behavior appears to follow that of a typical AVM. Gamma Knife radiosurgery appears to be a good alternative to resection, although long-term follow-up results require verification.