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Minimally invasive transforaminal lumbosacral interbody fusion

Peng-Yuan Chang and Michael Y. Wang

In minimally invasive spinal fusion surgery, transforaminal lumbar (sacral) interbody fusion (TLIF) is one of the most common procedures that provides both anterior and posterior column support without retraction or violation to the neural structure. Direct and indirect decompression can be done through this single approach. Preoperative plain radiographs and MR scan should be carefully evaluated. This video demonstrates a standard approach for how to perform a minimally invasive transforaminal lumbosacral interbody fusion.

The video can be found here: https://youtu.be/bhEeafKJ370.

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Differences in fixation strength among constructs of atlantoaxial fixation

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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Can segmental mobility be increased by cervical arthroplasty?

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

OBJECTIVE

Many reports have successfully demonstrated that cervical disc arthroplasty (CDA) can preserve range of motion after 1- or 2-level discectomy. However, few studies have addressed the extent of changes in segmental mobility after CDA or their clinical correlations.

METHODS

Data from consecutive patients who underwent 1-level CDA were retrospectively reviewed. Indications for surgery were medically intractable degenerative disc disease and spondylosis. Clinical outcomes, including visual analog scale (VAS)–measured neck and arm pain, Neck Disability Index (NDI), and Japanese Orthopaedic Association (JOA) scores, were analyzed. Radiographic outcomes, including C2–7 Cobb angle, the difference between pre- and postoperative C2–7 Cobb angle (ΔC2–7 Cobb angle), sagittal vertical axis (SVA), the difference between pre- and postoperative SVA (ΔSVA), segmental range of motion (ROM), and the difference between pre- and postoperative ROM (ΔROM), were assessed for their association with clinical outcomes. All patients underwent CT scanning, by which the presence and severity of heterotopic ossification (HO) were determined during the follow-up.

RESULTS

A total of 50 patients (mean age 45.6 ± 9.33 years) underwent a 1-level CDA (Prestige LP disc) and were followed up for a mean duration of 27.7 ± 8.76 months. All clinical outcomes, including VAS, NDI, and JOA scores, improved significantly after surgery. Preoperative and postoperative ROM values were similar (mean 9.5° vs 9.0°, p > 0.05) at each indexed level. The mean changes in segmental mobility (ΔROM) were −0.5° ± 6.13°. Patients with increased segmental mobility after surgery (ΔROM > 0°) had a lower incidence of HO and HO that was less severe (p = 0.048) than those whose ΔROM was < 0°. Segmental mobility (ROM) was significantly lower in patients with higher HO grade (p = 0.012), but it did not affect the clinical outcomes. The preoperative and postoperative C2–7 Cobb angles and SVA remained similar. The postoperative C2–7 Cobb angles, SVA, ΔC2–7 Cobb angles, and ΔSVA were not correlated to clinical outcomes after CDA.

CONCLUSIONS

Segmental mobility (as reflected by the mean ROM) and overall cervical alignment (i.e., mean SVA and C2–7 Cobb angle) had no significant impact on clinical outcomes after 1-level CDA. Patients with increased segmental mobility (ΔROM > 0°) had significantly less HO and similarly improved clinical outcomes than those with decreased segmental mobility (ΔROM < 0°).

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Stepwise illustration of teeth-fixation semi-constrained cervical disc arthroplasty

Chih-Chang Chang, Jau-Ching Wu, Peng-Yuan Chang, Mei-Yin Yeh, Yi-Hsuan Kuo, Li-Yu Fay, Tsung-Hsi Tu, Wen-Cheng Huang, and Henrich Cheng

There are many kinds of artificial discs available for cervical disc arthroplasty (CDA), with various designs of fixation and articulation mechanisms. Each of these designs has different features and theoretically fits most optimally in selected types of patients. However, there has been insufficient literature to guide individualized selection among these CDA devices. Since CDA aims to restore the joint function rather than arthrodesis, tailor-made size, shape, and mechanical properties should be taken into account for each candidate's target disc. Despite several large-scale prospective randomized control trials that have demonstrated the effectiveness and durability of CDA for up to 8 years, none of them involved more than one kind of artificial disc. In this video the authors present detailed steps and technical aspects of the newly introduced ProDisc-C Vivo (DePuy Synthes Spine), which has the same ball-and-socket design for controlled, predictable motion as the ProDisc-C. The newly derived teeth fixation provides high primary stability and multilevel capability by avoidance of previous keel-related limitations and complications (e.g., split vertebral fracture). Please note that the ProDisc-C Vivo is currently not available on the US market.

The authors present the case of a 53-year-old woman who had symptoms of both radiculopathy and myelopathy caused by a large, calcified disc herniation at C4–5. There was no improvement after 4 months of medical treatment and rehabilitation. A single-level CDA was successfully performed with the ProDisc-C Vivo, and her symptoms were completely ameliorated afterward. The follow-up images demonstrated preservation of motion at the indexed level.

The video can be found here: https://youtu.be/4DSES1xgvQU.

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Scoliosis may increase the risk of recurrence of lumbar disc herniation after microdiscectomy

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

OBJECT

The aim of this paper was to investigate the risk of recurrence of lumbar disc herniation (LDH) in patients with scoliosis who underwent microdiscectomy.

METHODS

A series of consecutive patients who underwent microdiscectomy for LDH was retrospectively reviewed. The inclusion criteria were young adults younger than 40 years who received microdiscectomy for symptomatic 1-level LDH. An exclusion criterion was any previous spinal surgery, including fusion or correction of scoliosis. The patients were divided into 2 groups: those with scoliosis and those without scoliosis. The demographic data in the 2 groups were similar. All medical records and clinical and radiological evaluations were reviewed.

RESULTS

A total of 58 patients who underwent 1-level microdiscectomy for LDH were analyzed. During the mean follow-up of 24.6 months, 6 patients (10.3%) experienced a recurrence of LDH with variable symptoms. The recurrence rate was significantly higher among the scoliosis group than the nonscoliosis group (33.3% vs 2.3%, p = 0.001). Furthermore, the recurrence-free interval in the scoliosis group was short.

CONCLUSIONS

Young adults (< 40 years) with uncorrected scoliosis are at higher risk of recurrent LDH after microdiscectomy.

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Endoscope-assisted minimally invasive transforaminal thoracic interbody fusion

Chih-Hsiang Liao, Jau-Ching Wu, Wen-Cheng Huang, Wei-Hsin Wang, Peng-Yuan Chang, Henrich Cheng, and Yang-Shih

Surgical treatment of thoracic disc herniation is technically challenging from anterior, lateral or posterior approaches. Because of the deeply located thoracic discs and non-retractable thoracic thecal sac, standard anterior and lateral procedures for discectomy require extensive tissue dissection causing prolonged lengths of stay in hospital. In this video, the authors present a case of calcified disc herniation at the level of T10/11 causing paraplegia and voiding difficulty. The patient was operated on via an endoscope-assisted minimally invasive transforaminal thoracic interbody fusion (EA-TTIF). The herniated disc and calcification were removed through a 26-mm tubular retractor, under microscopes via a unilateral transpedicular approach. The endoscopes were used for direct visualization of the ventral thecal sac and confirmation of complete decompression. After the operation, the patient's neurological function completely recovered. Minimally invasive EA-TTIF is a viable and effective option for the surgical management of thoracic disc herniation. Thoracic interbody fusion can be achieved through a minimally invasive approach from the back.

The video can be found here: http://youtu.be/54rRMtvSyCM.

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Dynamic stabilization for L4–5 spondylolisthesis: comparison with minimally invasive transforaminal lumbar interbody fusion with more than 2 years of follow-up

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

OBJECTIVE

In the past decade, dynamic stabilization has been an emerging option of surgical treatment for lumbar spondylosis. However, the application of this dynamic construct for mild spondylolisthesis and its clinical outcomes remain uncertain. This study aimed to compare the outcomes of Dynesys dynamic stabilization (DDS) with minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) for the management of single-level spondylolisthesis at L4–5.

METHODS

This study retrospectively reviewed 91 consecutive patients with Meyerding Grade I spondylolisthesis at L4–5 who were managed with surgery. Patients were divided into 2 groups: DDS and MI-TLIF. The DDS group was composed of patients who underwent standard laminectomy and the DDS system. The MI-TLIF group was composed of patients who underwent MI-TLIF. Clinical outcomes were evaluated by visual analog scale for back and leg pain, Oswestry Disability Index, and Japanese Orthopaedic Association scores at each time point of evaluation. Evaluations included radiographs and CT scans for every patient for 2 years after surgery.

RESULTS

A total of 86 patients with L4–5 spondylolisthesis completed the follow-up of more than 2 years and were included in the analysis (follow-up rate of 94.5%). There were 64 patients in the DDS group and 22 patients in the MI-TLIF group, and the overall mean follow-up was 32.7 months. Between the 2 groups, there were no differences in demographic data (e.g., age, sex, and body mass index) or preoperative clinical evaluations (e.g., visual analog scale back and leg pain, Oswestry Disability Index, and Japanese Orthopaedic Association scores). The mean estimated blood loss of the MI-TLIF group was lower, whereas the operation time was longer compared with the DDS group (both p < 0.001). For both groups, clinical outcomes were significantly improved at 6, 12, 18, and 24 months after surgery compared with preoperative clinical status. Moreover, there were no differences between the 2 groups in clinical outcomes at each evaluation time point. Radiological evaluations were also similar and the complication rates were equally low in both groups.

CONCLUSIONS

At 32.7 months postoperation, the clinical and radiological outcomes of DDS were similar to those of MI-TLIF for Grade I degenerative spondylolisthesis at L4–5. DDS might be an alternative to standard arthrodesis in mild lumbar spondylolisthesis. However, unlike fusion, dynamic implants have issues of wearing and loosening in the long term. Thus, the comparable results between the 2 groups in this study require longer follow-up to corroborate.

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Dynesys dynamic stabilization–related facet arthrodesis

Li-Yu Fay, Peng-Yuan Chang, Jau-Ching Wu, Wen-Cheng Huang, Chun-Hao Wang, Tzu-Yun Tsai, Tsung-Hsi Tu, Hsuan-Kan Chang, Ching-Lan Wu, and Henrich Cheng

OBJECTIVE

Dynamic stabilization devices are designed to stabilize the spine while preserving some motion. However, there have been reports demonstrating limited motion at the instrumented level of the lumbar spine after Dynesys dynamic stabilization (DDS). The causes of this limited motion and its actual effects on outcomes after DDS remain elusive. In this study, the authors investigate the incidence of unintended facet arthrodesis after DDS and clinical outcomes.

METHODS

This retrospective study included 80 consecutive patients with 1- or 2-level lumbar spinal stenosis who underwent laminectomy and DDS. All medical records, radiological data, and clinical evaluations were analyzed. Imaging studies included pre- and postoperative radiographs, MR images, and CT scans. Clinical outcomes were measured by a visual analog scale (VAS) for back and leg pain, the Oswestry Disability Index (ODI), and Japanese Orthopaedic Association (JOA) scores. Furthermore, all patients had undergone postoperative CT for the detection of unintended arthrodesis of the facets at the indexed level, and range of motion was measured on standing dynamic radiographs.

RESULTS

A total of 70 patients (87.5%) with a mean age of 64.0 years completed the minimum 24-month postoperative follow-up (mean duration 29.9 months). Unintended facet arthrodesis at the DDS instrumented level was demonstrated by CT in 38 (54.3%) of the 70 patients. The mean age of patients who had facet arthrodesis was 9.8 years greater than that of the patients who did not (68.3 vs 58.5 years, p = 0.009). There were no significant differences in clinical outcomes, including VAS back and leg pain, ODI, and JOA scores between patients with and without the unintended facet arthrodesis. Furthermore, those patients older than 60 years were more likely to have unintended facet arthrodesis (OR 12.42) and immobile spinal segments (OR 2.96) after DDS. Regardless of whether unintended facet arthrodesis was present or not, clinical evaluations demonstrated improvement in all patients (all p < 0.05).

CONCLUSIONS

During the follow-up of more than 2 years, unintended facet arthrodesis was demonstrated in 54.3% of the patients who underwent 1- or 2-level DDS. Older patients (age > 60 years) were more likely to have unintended facet arthrodesis and subsequent immobile spinal segments. However, unintended facet arthrodesis did not affect the clinical outcomes during the study period. Further evaluations are needed to clarify the actual significance of this phenomenon.

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Letter to the Editor. Hybrid cervical disc arthroplasty for cervical myelopathy associated with congenital cervical stenosis

Yawei Li, Guohua Lv, and Bing Wang

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Letters to the editor: Hypermobility accelerates adjacent-segment disease after ACDF?

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