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Timur M. Urakov, Ken Hsuan-kan Chang, S. Shelby Burks and Michael Y. Wang

OBJECTIVE

Spine surgery is complex and involves various steps. Current robotic technology is mostly aimed at assisting with pedicle screw insertion. This report evaluates the feasibility of robot-assisted pedicle instrumentation in an academic environment with the involvement of residents and fellows.

METHODS

The Renaissance Guidance System was used to plan and execute pedicle screw placement in open and percutaneous consecutive cases performed in the period of December 2015 to December 2016. The database was reviewed to assess the usability of the robot by neurosurgical trainees. Outcome measures included time per screw, fluoroscopy time, breached screws, and other complications. Screw placement was assessed in patients with postoperative CT studies. The speed of screw placement and fluoroscopy time were collected at the time of surgery by personnel affiliated with the robot’s manufacturer. Complication and imaging data were reviewed retrospectively.

RESULTS

A total of 306 pedicle screws were inserted in 30 patients with robot guidance. The average time for junior residents was 4.4 min/screw and for senior residents and fellows, 4.02 min/screw (p = 0.61). Among the residents dedicated to spine surgery, the average speed was 3.84 min/screw, while nondedicated residents took 4.5 min/screw (p = 0.41). Evaluation of breached screws revealed some of the pitfalls in using the robot.

CONCLUSIONS

No significant difference regarding the speed of pedicle instrumentation was detected between the operators’ years of experience or dedication to spine surgery, although more participants are required to investigate this completely. On the other hand, there was a trend toward improved efficiency with more cases performed. To the authors’ knowledge, this is the first reported academic experience with robot-assisted spine instrumentation.

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Giacomo Pacchiarotti, Michael Y. Wang, John Paul G. Kolcun, Ken Hsuan-kan Chang, Motasem Al Maaieh, Victor S. Reis and Dao M. Nguyen

Solitary paravertebral schwannomas in the thoracic spine and lacking an intraspinal component are uncommon. These benign nerve sheath tumors are typically treated using complete resection with an excellent outcome. Resection of these tumors is achieved by an anterior approach via open thoracotomy or minimally invasive thoracoscopy, by a posterior approach via laminectomy, or by a combination of both approaches. These tumors most commonly occur in the midthoracic region, for which surgical removal is usually straightforward. The authors of this report describe 2 cases of paravertebral schwannoma at extreme locations of the posterior mediastinum, one at the superior sulcus and the other at the inferior sulcus of the thoracic cavity, for which the usual surgical approaches for safe resection can be challenging. The tumors were completely resected with robot-assisted thoracoscopic surgery. This report suggests that single-stage anterior surgery for this type of tumor in extreme locations is safe and effective with this novel minimally invasive technique.

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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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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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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.