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  • Journal of Neurosurgery: Spine x
  • By Author: Cheng, Henrich x
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Li-Yu Fay, Wen-Cheng Huang, Chih-Chang Chang, Hsuan-Kan Chang, Tzu-Yun Tsai, Tsung-Hsi Tu, Ching-Lan Wu, Henrich Cheng and Jau-Ching Wu

OBJECTIVE

The pedicle screw–based Dynesys dynamic stabilization (DDS) has reportedly become a surgical option for lumbar spondylosis and spondylolisthesis. However, it is still unclear whether the dynamic construct remains mobile or eventually fuses. The aim of this study was to investigate the incidence of unintended facet arthrodesis after DDS and its association with spondylolisthesis.

METHODS

This retrospective study was designed to review 105 consecutive patients with 1- or 2-level lumbar spondylosis who were treated with DDS surgery. The patients were then divided into 2 groups according to preexisting spondylolisthesis or not. All patients underwent laminectomies, foraminotomies, and DDS. The clinical outcomes were measured using visual analog scale (VAS) scores for back and leg pain, Japanese Orthopaedic Association (JOA) scores, and Oswestry Disability Index (ODI) scores. All medical records, including pre- and postoperative radiographs, CT scans, and MR images, were also reviewed and compared.

RESULTS

A total of 96 patients who completed the postoperative follow-up for more than 30 months were analyzed. The mean age was 64.1 ± 12.9 years, and the mean follow-up duration was 46.3 ± 12.0 months. There were 45 patients in the spondylolisthesis group and 51 patients in the nonspondylolisthesis group. The overall prevalence rate of unintended facet fusion was 52.1% in the series of DDS. Patients with spondylolisthesis were older (67.8 vs 60.8 years, p = 0.007) and had a higher incidence rate of facet arthrodesis (75.6% vs 31.4%, p < 0.001) than patients without spondylolisthesis. Patients who had spondylolisthesis or were older than 65 years were more likely to have facet arthrodesis (OR 6.76 and 4.82, respectively). There were no significant differences in clinical outcomes, including VAS back and leg pain, ODI, and JOA scores between the 2 groups. Furthermore, regardless of whether or not unintended facet arthrodesis occurred, all patients experienced significant improvement (all p < 0.05) in the clinical evaluations.

CONCLUSIONS

During the mean follow-up of almost 4 years, the prevalence of unintended facet arthrodesis was 52.1% in patients who underwent DDS. Although the clinical outcomes were not affected, elderly patients with spondylolisthesis might have a greater chance of facet fusion. This could be a cause of the limited range of motion at the index levels long after DDS.

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Chih-Chang Chang, Wen-Cheng Huang, Tsung-Hsi Tu, Peng-Yuan Chang, Li-Yu Fay, Jau-Ching Wu and Henrich Cheng

OBJECTIVE

To avoid jeopardizing an aberrant vertebral artery, there are three common options in placing a C2 screw, including pedicle, pars, and translaminar screws. Although biomechanical studies have demonstrated similar strength among these C2 screws in vitro, there are limited clinical data to address their differences in vivo. When different screws were placed in each side, few reports have compared the outcomes. The present study aimed to evaluate these multiple combinations of C2 screws.

METHODS

Consecutive adult patients who underwent posterior atlantoaxial (AA) fixation were retrospectively reviewed. Every patient uniformly had bilateral C1 lateral mass screws in conjunction with 2 C2 screws (1 C2 screw on each side chosen among the three options: pedicle, pars, or translaminar screws, based on individualized anatomical consideration). These patients were then grouped according to the different combinations of C2 screws for comparison of the outcomes.

RESULTS

A total of 63 patients were analyzed, with a mean follow-up of 34.3 months. There were five kinds of construct combinations of the C2 screws: 2 pedicle screws (the Ped-Ped group, n = 24), 2 translaminar screws (the La-La group, n = 7), 2 pars screws (the Pars-Pars group, n = 6), 1 pedicle and 1 pars screw (the Ped-Pars group, n = 7), and 1 pedicle and 1 translaminar screw (the Ped-La group, n = 19). The rate of successful fixation in each of the groups was 100%, 57.1%, 100%, 100%, and 78.9% (Ped-Ped, La-La, Par-Par, Ped-Par, and Ped-La, respectively). The patients who had no translaminar screw had a higher rate of success than those who had 1 or 2 translaminar screws (100% vs 73.1%, p = 0.0009). Among the 5 kinds of construct combinations, 2 C2 pedicle screws (the Ped-Ped group) had higher rates of success than 1 C2 pedicle and 1 C2 translaminar screw (the Ped-La group, p = 0.018). Overall, the rate of successful fixation was 87.3% (55/63). There were 7 patients (4 in the Ped-La group and 3 in the La-La group) who lost fixation/reduction, and they all had at least 1 translaminar screw.

CONCLUSIONS

In AA fixation, C2 pedicle or pars screws or a combination of both provided very high success rates. Involvement of 1 or 2 C2 translaminar screws in the construct significantly lowered success rates. Therefore, a C2 pars screw is recommended over a translaminar screw.

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Chao-Hung Kuo, Wen-Cheng Huang, Jau-Ching Wu, Tsung-Hsi Tu, Li-Yu Fay, Ching-Lan Wu and Henrich Cheng

OBJECTIVE

Pedicle screw–based dynamic stabilization has been an alternative to conventional lumbar fusion for the surgical management of low-grade spondylolisthesis. However, the true effect of dynamic stabilization on adjacent-segment degeneration (ASD) remains undetermined. Authors of this study aimed to investigate the incidence of ASD and to compare the clinical outcomes of dynamic stabilization and minimally invasive transforaminal lumbar interbody fusion (MI-TLIF).

METHODS

The records of consecutive patients with Meyerding grade I degenerative spondylolisthesis who had undergone surgical management at L4–5 in the period from 2007 to 2014 were retrospectively reviewed. Patients were divided into two groups according to the surgery performed: Dynesys dynamic stabilization (DDS) group and MI-TLIF group. Pre- and postoperative radiological evaluations, including radiography, CT, and MRI studies, were compared. Adjacent discs were evaluated using 4 radiological parameters: instability (antero- or retrolisthesis), disc degeneration (Pfirrmann classification), endplate degeneration (Modic classification), and range of motion (ROM). Clinical outcomes, measured with the visual analog scale (VAS) for back and leg pain, the Oswestry Disability Index (ODI), and the Japanese Orthopaedic Association (JOA) scores, were also compared.

RESULTS

A total of 79 patients with L4–5 degenerative spondylolisthesis were included in the analysis. During a mean follow-up of 35.2 months (range 24–89 months), there were 56 patients in the DDS group and 23 in the MI-TLIF group. Prior to surgery, both groups were very similar in demographic, radiological, and clinical data. Postoperation, both groups had similarly significant improvement in clinical outcomes (VAS, ODI, and JOA scores) at each time point of evaluation. There was a lower chance of disc degeneration (Pfirrmann classification) of the adjacent discs in the DDS group than in the MI-TLIF group (17% vs 37%, p = 0.01). However, the DDS and MI-TLIF groups had similar rates of instability (15.2% vs 17.4%, respectively, p = 0.92) and endplate degeneration (1.8% vs 6.5%, p = 0.30) at the cranial (L3–4) and caudal (L5–S1) adjacent levels after surgery. The mean ROM in the cranial and caudal levels was also similar in the two groups. None of the patients required secondary surgery for any ASD (defined by radiological criteria).

CONCLUSIONS

The clinical improvements after DDS were similar to those following MI-TLIF for L4–5 Meyerding grade I degenerative spondylolisthesis at 3 years postoperation. According to radiological evaluations, there was a lower chance of disc degeneration in the adjacent levels of the patients who had undergone DDS. However, other radiological signs of ASD, including instability, endplate degeneration, and ROM, were similar between the two groups. Although none of the patients in the present series required secondary surgery, a longer follow-up and a larger number of patients would be necessary to corroborate the protective effect of DDS against ASD.

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Zhiming Tu, Yawei Li, Lei Li, Guohua Lv and Bing Wang

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Peng-Yuan Chang, Hsuan-Kan Chang, Jau-Ching Wu, Wen-Cheng Huang, Li-Yu Fay, Tsung-Hsi Tu, Ching-Lan Wu and Henrich Cheng

OBJECTIVE

Cervical disc arthroplasty (CDA) has been demonstrated to be as safe and effective as anterior cervical discectomy and fusion (ACDF) in the management of 1- and 2-level degenerative disc disease (DDD). However, there has been a lack of data to address the fundamental discrepancy between the two surgeries (CDA vs ACDF), and preservation versus elimination of motion, in the management of cervical myelopathy associated with congenital cervical stenosis (CCS). Although younger patients tend to benefit more from motion preservation, it is uncertain if CCS caused by multilevel DDD can be treated safely with CDA.

METHODS

Consecutive patients who underwent 3-level anterior cervical discectomy were retrospectively reviewed. Inclusion criteria were age less than 50 years, CCS (Pavlov ratio ≤ 0.82), symptomatic myelopathy correlated with DDD, and stenosis limited to 3 levels of the subaxial cervical (C3–7) spine. Exclusion criteria were ossification of the posterior longitudinal ligament, previous posterior decompression surgery (e.g., laminoplasty or laminectomy), osteoporosis, previous trauma, or other rheumatic diseases that might have caused the cervical myelopathy. All these patients who underwent 3-level discectomy were divided into 2 groups according to the strategies of management: preservation or elimination of motion (the hybrid-CDA group and the ACDF group). The hybrid-CDA group underwent 2-level CDA plus 1-level ACDF, whereas the ACDF group underwent 3-level ACDF. Clinical assessment was measured by the visual analog scales (VAS) for neck and arm pain, Japanese Orthopaedic Association (JOA) scores, and Nurick grades. Radiographic outcomes were measured using dynamic radiographs for evaluation of range of motion (ROM).

RESULTS

Thirty-seven patients, with a mean (± SD) age of 44.57 ± 5.10 years, were included in the final analysis. There was a male predominance in this series (78.4%, 29 male patients), and the mean follow-up duration was 2.37 ± 1.60 years. There were 20 patients in the hybrid-CDA group, and 17 in the ACDF group. Both groups demonstrated similar clinical improvement at 2 years' follow-up. These patients with 3-level stenosis experienced significant improvement after either type of surgery (hybrid-CDA and ACDF). There were no significant differences between the 2 groups at each of the follow-up visits postoperatively. The preoperative ROM over the operated subaxial levels was similar between both groups (21.9° vs 21.67°; p = 0.94). Postoperatively, the hybrid-CDA group had significantly greater ROM (10.65° vs 2.19°; p < 0.001) than the ACDF group. Complications, adverse events, and reoperations in both groups were similarly low.

CONCLUSIONS

Hybrid-CDA yielded similar clinical improvement to 3-level ACDF in patients with myelopathy caused by CCS. In this relatively young group of patients, hybrid-CDA demonstrated significantly more ROM than 3-level ACDF without adjacent-segment disease (ASD) at 2 years' follow-up. Therefore, hybrid-CDA appears to be an acceptable option in the management of CCS. The strategy of motion preservation yielded similar improvements of cervical myelopathy to motion elimination (i.e., ACDF) in patients with CCS, while the theoretical benefit of reducing ASD required further validation.

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Chih-Chang Chang, Li-Yu Fay, Jau-Ching Wu, Peng-Yuan Chang, Tsung-Hsi Tu, Henrich Cheng and Wen-Cheng Huang

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Yu-Wen Cheng, Peng-Yuan Chang, Jau-Ching Wu, Chih-Chang Chang, Li-Yu Fay, Tsung-Hsi Tu, Wen-Cheng Huang and Henrich Cheng

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Chih-Chang Chang, Ching-Lan Wu, Jau-Ching Wu, Hsuan-Kan Chang, Li-Yu Fay, Tsung-Hsi Tu, Wen-Cheng Huang and Henrich Cheng

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Peng-Yuan Chang, Hsuan-Kan Chang, Jau-Ching Wu, Wen-Cheng Huang, Li-Yu Fay, Tsung-Hsi Tu, Ching-Lan Wu and Henrich Cheng

OBJECTIVE

Several large-scale clinical trials demonstrate the efficacy of 1- and 2-level cervical disc arthroplasty (CDA) for degenerative disc disease (DDD) in the subaxial cervical spine, while other studies reveal that during physiological neck flexion, the C4–5 and C5–6 discs account for more motion than the C3–4 level, causing more DDD. This study aimed to compare the results of CDA at different levels.

METHODS

After a review of the medical records, 94 consecutive patients who underwent single-level CDA were divided into the C3–4 and non-C3–4 CDA groups (i.e., those including C4–5, C5–6, and C6–7). Clinical outcomes were measured using the visual analog scale for neck and arm pain and by the Japanese Orthopaedic Association scores. Postoperative range of motion (ROM) and heterotopic ossification (HO) were determined by radiography and CT, respectively.

RESULTS

Eighty-eight patients (93.6%; mean age 45.62 ± 10.91 years), including 41 (46.6%) female patients, underwent a mean follow-up of 4.90 ± 1.13 years. There were 11 patients in the C3–4 CDA group and 77 in the non-C3–4 CDA group. Both groups had significantly improved clinical outcomes at each time point after the surgery. The mean preoperative (7.75° vs 7.03°; p = 0.58) and postoperative (8.18° vs 8.45°; p = 0.59) ROMs were similar in both groups. The C3–4 CDA group had significantly greater prevalence (90.9% vs 58.44%; p = 0.02) and higher severity grades (2.27 ± 0.3 vs 0.97 ± 0.99; p = 0.0001) of HO.

CONCLUSIONS

Although CDA at C3–4 was infrequent, the improved clinical outcomes of CDA were similar at C3–4 to that in the other subaxial levels of the cervical spine at the approximately 5-year follow-ups. In this Asian population, who had a propensity to have ossification of the posterior longitudinal ligament, there was more HO formation in patients who received CDA at the C3–4 level than in other subaxial levels of the cervical spine. While the type of artificial discs could have confounded the issue, future studies with more patients are required to corroborate the phenomenon.