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Karthik Madhavan, Lee Onn Chieng, Lynn McGrath, Christoph P. Hofstetter and Michael Y. Wang

OBJECTIVE

Asymmetrical degeneration of the disc is one of the most common causes of primary degenerative scoliosis in adults. Coronal deformity is usually less symptomatic than a sagittal deformity because there is less expenditure of energy and hence less effort to maintain upright posture. However, nerve root compression at the fractional curve or at the concave side of the main curve can give rise to debilitating radiculopathy.

METHODS

This study was a retrospective analysis of 16 patients with coronal deformity of between 10° and 20°. All patients underwent endoscopic foraminal decompression surgery. The pre- and postoperative Cobb angle, visual analog scale (VAS), 36-Item Short Form Health Survey (SF-36), and Oswestry Disability Index scores were measured.

RESULTS

The average age of the patients was 70.0 ± 15.5 years (mean ± SD, range 61–86 years), with a mean followup of 7.5 ± 5.3 months (range 2–14 months). The average coronal deformity was 16.8° ± 4.7° (range 10°–41°). In 8 patients the symptomatic foraminal stenosis was at the level of the fractional curve, and in the remaining patients it was at the concave side of the main curve. One of the patients included in the current cohort had to undergo a repeat operation within 1 week for another disc herniation at the adjacent level. One patient had CSF leakage, which was repaired intraoperatively, and no further complications were noted. On average, preoperative VAS and SF-36 scores showed a tendency for improvement, whereas a dramatic reduction of VAS, by 65% (p = 0.003), was observed in radicular leg pain.

CONCLUSIONS

Patients with mild to moderate spinal deformity are often compensated and have tolerable levels of back pain. However, unilateral radicular pain resulting from foraminal stenosis can be debilitating. In select cases, an endoscopic discectomy or foraminotomy enables the surgeon to decompress the symptomatic foramen with preservation of essential biomechanical structures, delaying the need for a major deformity correction surgery.

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Lynn B. McGrath Jr., Karthik Madhavan, Lee Onn Chieng, Michael Y. Wang and Christoph P. Hofstetter

Approximately half a million spinal fusion procedures are performed annually in the US. It is estimated that up to one-third of arthrodesis constructs require revision surgeries. In this study the authors present endoscopic treatment strategies targeting 3 types of complications following arthrodesis surgery: 1) adjacent-level foraminal stenosis; 2) foraminal stenosis at an arthrodesis segment; and 3) stenosis caused by a displaced interbody cage.

A retrospective chart review of 11 patients with a mean age of 68 ± 15 years was performed (continuous variables are shown as the mean ± SEM). All patients had a history of lumbar arthrodesis surgery and suffered from unilateral radiculopathy. Endoscopic revision surgeries were done as outpatient procedures, and there were no intraoperative or perioperative complications. The cohort included 3 patients with foraminal stenosis at the level of previous arthrodesis. They presented with unilateral radicular leg pain (visual analog scale [VAS] score: 7.3 ± 2.1) and were severely disabled, as evidenced by an Oswestry Disability Index (ODI) of 46 ± 4.9. Transforaminal endoscopic foraminotomies were performed, and at a mean follow-up time of 9.0 ± 2.5 months VAS was reduced by an average of 6.3. The cohort also includes 7 patients suffering unilateral radiculopathy due to adjacent-level foraminal stenosis. Preoperative VAS for leg pain of the symptomatic side was 6.0 ± 1.6, VAS for back pain was 5.2 ± 1.7, and ODI was 40 ± 6.33. Endoscopic decompression led to reduction of the ipsilateral leg VAS score by an average of 5, resulting in leg pain of 1 ± 0.5 at an average of 8 months of follow-up. The severity of back pain remained stable (VAS 4.2 ± 1.4). Two of these patients required revision surgery for recurrent symptoms. Finally, this study includes 1 patient who presented with weakness and pain due to retropulsion of an L5/S1 interbody spacer. The patient underwent an endoscopic interlaminar approach with partial resection of the interbody cage, which resulted in complete resolution of her radicular symptoms.

Endoscopic surgery may be a useful adjunct for management of certain arthrodesis-related complications. Endoscopic foraminal decompression of previously fused segments and resection of displaced interbody cages appears to have excellent outcomes, whereas decompression of adjacent segments remains challenging and requires further investigation.

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Michael Y. Wang and Jay Grossman

OBJECTIVE

One of the principal goals of minimally invasive surgery has been to speed postoperative recovery. In this case series, the authors used an endoscopic technique for interbody fusion combined with percutaneous screw fixation to obviate the need for general anesthesia.

METHODS

The first 10 consecutive patients treated with a minimum of 1 year's follow-up were included in this series. The patients were all treated using endoscopic access through Kambin's triangle to allow for neural decompression, discectomy, endplate preparation, and interbody fusion. This was followed by percutaneous pedicle screw and connecting rod placement using liposomal bupivacaine for long-acting analgesia. No narcotics or regional anesthetics were used during surgery.

RESULTS

All patients underwent the procedure successfully without conversion to open surgery. The patients' average age was 62.2 ± 9.0 years (range 52–78 years). All patients had severe disc height collapse, and 60% had a Grade I spondylolisthesis. The mean operative time was 113.5 ± 6.3 minutes (range 105–120 minutes), and blood loss was 65 ± 38 ml (range 30–190 ml). The mean length of hospital stay was 1.4 ± 1.3 nights. There were no intraoperative or postoperative complications. Comparison of preoperative and final clinical metrics demonstrated that the Oswestry Disability Index improved from 42 ± 11.8 to 13.3 ± 15.1; the 36-Item Short Form Health Survey (SF-36) Physical Component Summary improved from 47.6 ± 3.8 to 49.7 ± 5.4; the SF-36 Mental Component Summary decreased from 47 ± 3.9 to 46.7 ± 3.4; and the EQ-5D improved from 10.7 ± 9.5 to 14.2 ± 1.6. There were no cases of nonunion identified radiographically on follow-up imaging.

CONCLUSIONS

Endoscopic fusion under conscious sedation may represent a feasible alternative to traditional lumbar spine fusion in select patients. Larger clinical series are necessary to validate that clinical improvements are sustained and that arthrodesis rates are successful when compared with open surgery. This initial experience demonstrates the possible utility of this procedure.

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Ziya L. Gokaslan, Albert E. Telfeian and Michael Y. Wang

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Karthik Madhavan, Lee Onn Chieng, Christoph P. Hofstetter and Michael Y. Wang

Isthmic spondylolisthesis due to pars defects resulting from trauma or spondylolysis is not uncommon. Symptomatic patients with such pars defects are traditionally treated with a variety of fusion surgeries. The authors present a unique case in which such a patient was successfully treated with endoscopic discectomy without iatrogenic destabilization.

A 31-year-old man presented with a history of left radicular leg pain along the distribution of the sciatic nerve. He had a disc herniation at L5/S1 and bilateral pars defects with a Grade I spondylolisthesis. Dynamic radiographic studies did not show significant movement of L-5 over S-1. The patient did not desire to have a fusion. After induction of local anesthesia, the patient underwent an awake transforaminal endoscopic discectomy via the extraforaminal approach, with decompression of the L-5 and S-1 nerve roots. His preoperative pain resolved immediately, and he was discharged home the same day. His preoperative Oswestry Disability Index score was 74, and postoperatively it was noted to be 8. At 2-year follow-up he continued to be symptom free, and no radiographic progression of the listhesis was noted.

In this case preservation of stabilizing structures, including the supraspinous and interspinous ligaments and the facet capsule, may have reduced the likelihood of iatrogenic instability while at the same time achieving symptom control. This may be a reasonable option for select patient symptoms confined to lumbosacral radiculopathy.

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Michael Y. Wang, Gabriel Widi and Allan D. Levi

OBJECT

The aging of the population will require that surgeons increasingly consider operating on elderly patients. Performing surgery safely in the elderly will require an understanding of the factors that predict successful outcomes and avoid complications.

METHODS

Records of patients 85 years and older undergoing elective lumbar spinal surgery were retrospectively reviewed. Microdiscectomies were excluded. Preexisting medical illnesses measured using the Charlson Comorbidity Index (CCI), American Society of Anesthesiologists (ASA) Physical Status class, age, and surgical parameters were analyzed as factors potentially predictive of complications. Ambulatory function was rated on a 4-point scale.

RESULTS

During the study 26 consecutive patients (mean age 87 years) with a mean ASA class of 2.6 ± 0.65 and CCI of 1.1 ± 1.27 were enrolled. The average number of levels treated was 2.17 ± 1.23, and 73% underwent fusion. The mean follow-up was 41.9 months with a minimum of 24 months, and all patients were alive at last follow-up. Average blood loss was 142 ± 184 ml, and the operative time was 183.3 ± 80.6 minutes. The mean number of levels treated was 2.17 ± 1.13 (range 1–4). Ambulatory function improved significantly by 0.59 ± 1.0 points. Five complications (19.2%) occurred in 4 patients, 2 major and 3 minor. Four complications were temporary and 1 was permanent. Patient age, blood loss, CCI score, ASA class, the number of levels treated, and fusion surgery were not statistically associated with a complication. Operative time of longer than 180 minutes (p = 0.0134) was associated with complications.

CONCLUSIONS

Lumbar spine surgery in patients 85 years and older can be accomplished safely if careful attention is paid to preoperative selection. Prolonged operative times are associated with a higher risk of complications.

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Paul Park, Michael Y. Wang, Virginie Lafage, Stacie Nguyen, John Ziewacz, David O. Okonkwo, Juan S. Uribe, Robert K. Eastlack, Neel Anand, Raqeeb Haque, Richard G. Fessler, Adam S. Kanter, Vedat Deviren, Frank La Marca, Justin S. Smith, Christopher I. Shaffrey, Gregory M. Mundis Jr. and Praveen V. Mummaneni

OBJECT

Minimally invasive surgery (MIS) techniques are becoming a more common means of treating adult spinal deformity (ASD). The aim of this study was to compare the hybrid (HYB) surgical approach, involving minimally invasive lateral interbody fusion with open posterior instrumented fusion, to the circumferential MIS (cMIS) approach to treat ASD.

METHODS

The authors performed a retrospective, multicenter study utilizing data collected in 105 patients with ASD who were treated via MIS techniques. Criteria for inclusion were age older than 45 years, coronal Cobb angle greater than 20°, and a minimum of 1 year of follow-up. Patients were stratified into 2 groups: HYB (n = 62) and cMIS (n = 43).

RESULTS

The mean age was 60.7 years in the HYB group and 61.0 years in the cMIS group (p = 0.910). A mean of 3.6 interbody fusions were performed in the HYB group compared with a mean of 4.0 interbody fusions in the cMIS group (p = 0.086). Posterior fusion involved a mean of 6.9 levels in the HYB group and a mean of 5.1 levels in the cMIS group (p = 0.003). The mean follow-up was 31.3 months for the HYB group and 38.3 months for the cMIS group. The mean Oswestry Disability Index (ODI) score improved by 30.6 and 25.7, and the mean visual analog scale (VAS) scores for back/leg pain improved by 2.4/2.5 and 3.8/4.2 for the HYB and cMIS groups, respectively. There was no significant difference between groups with regard to ODI or VAS scores. For the HYB group, the lumbar coronal Cobb angle decreased by 13.5°, lumbar lordosis (LL) increased by 8.2°, sagittal vertical axis (SVA) decreased by 2.2 mm, and LL–pelvic incidence (LL-PI) mismatch decreased by 8.6°. For the cMIS group, the lumbar coronal Cobb angle decreased by 10.3°, LL improved by 3.0°, SVA increased by 2.1 mm, and LL-PI decreased by 2.2°. There were no significant differences in these radiographic parameters between groups. The complication rate, however, was higher in the HYB group (55%) than in the cMIS group (33%) (p = 0.024).

CONCLUSIONS

Both HYB and cMIS approaches resulted in clinical improvement, as evidenced by decreased ODI and VAS pain scores. While there was no significant difference in degree of radiographic correction between groups, the HYB group had greater absolute improvement in degree of lumbar coronal Cobb angle correction, increased LL, decreased SVA, and decreased LL-PI. The complication rate, however, was higher with the HYB approach than with the cMIS approach.

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Michael Y. Wang, Ram Vasudevan and Stefan A. Mindea

Object

Adjacent-segment degeneration and stenosis are common in patients who have undergone previous lumbar fusion. Treatment typically involves a revision posterior approach, which requires management of postoperative scar tissue and previously implanted instrumentation. A minimally invasive lateral approach allows the surgeon to potentially reduce the risk of these hazards. The technique relies on indirect decompression to treat central and foraminal stenosis and placement of a graft with a large surface area to promote robust fusion and stability in concert with the surrounding tensioned ligaments. The goal in this study was to determine if lateral interbody fusion without supplemental pedicle screws is effective in treating adjacent-segment disease.

Methods

For a 30-month study period at two institutions, the authors obtained all cases of lumbar fusion with new back and leg pain due to adjacent-segment stenosis and spondylosis failing conservative measures. All patients had undergone minimally invasive lateral interbody fusion from the side of greater leg pain without supplemental pedicle screw fixation. Patients were excluded from the study if they had undergone surgery for a nondegenerative etiology such as infection or trauma. They were also excluded if the intervention involved supplemental posterior instrumented fusion with transpedicular screws. Postoperative metrics included numeric pain scale (NPS) scores for leg and back pain. All patients underwent dynamic radiographs and CT scanning to assess stability and fusion after surgery.

Results

During the 30-month study period, 21 patients (43% female) were successfully treated using minimally invasive lateral interbody fusion without the need for subsequent posterior transpedicular fixation. The mean patient age was 61 years (range 37–87 years). Four patients had two adjacent levels fused, while the remainder had single-level surgery. All patients underwent surgery without conversion to a traditional open technique, and recombinant human bone morphogenetic protein–2 was used in the interbody space in all cases. The mean follow-up was 23.6 months. The mean operative time was 86 minutes, and the mean blood loss was 93 ml. There were no major intraoperative complications, but one patient underwent subsequent direct decompression in a delayed fashion. The leg pain NPS score improved from a mean of 6.3 to 1.9 (p < 0.01), and the back pain NPS score improved from a mean of 7.5 to 2.9 (p < 0.01). Intervertebral settling averaged 1.7 mm. All patients had bridging bone on CT scanning at the last follow-up, indicating solid bony fusion.

Conclusions

Adjacent-segment stenosis and spondylosis can be treated with a number of different operative techniques. Lateral interbody fusion provides an attractive alternative with reduced blood loss and complications, as there is no need to re-explore a previous laminectomy site. In this limited series a minimally invasive lateral approach provided high fusion rates when performed with osteobiological adjuvants.