Two-level Discectomy Research Articles

Comparison of clinical outcomes in patients undergoing one- and two-level minimally invasive lumbar microdiscectomy.

Herniated nucleus pulposus (HNP) is one of the most common lumbar spine conditions treated surgically, often through a minimally invasive surgery (MIS) microdiscectomy approach. This technique attempts to reduce damage to the paraspinal muscular-ligamentous envelope. However, there are currently limited data regarding comparative outcomes using patient-reported outcome measures (PROMs) for one- and two-level MIS discectomies. The aim of this study was to quantify comparative clinical outcomes in patients undergoing one-level and two-level MIS lumbar microdiscectomy for HNP using PROMs. The authors performed a retrospective review of patients undergoing MIS lumbar microdiscectomy between 2004 and 2019 for the primary diagnosis of HNP at a single academic institution. All patients had a minimum 1-year follow-up. Patient demographics and comorbidities were collected to establish baselines between cohorts. PROMs and minimal clinically important differences (MCIDs) were used to examine the patient's perception of operative success. Bivariate and multivariate linear/logistic regression analyses were used to compare one- and two-level discectomies. The bivariate analysis included the t-test and chi-square test, which were used to assess continuous and categorical variables, respectively. Statistical significance was established at p < 0.05. A total of 293 patients underwent one-level (n = 250) or two-level (n = 43) MIS discectomies. The mean follow-ups for the one- and two-level cohorts were 50.4 (SD 35.5) months and 61.6 (SD 39.8) months, respectively. Fewer female patients underwent two-level discectomies, and BMI and operative duration were higher in the two-level group (p < 0.001). Recurrent herniation requiring reoperation was recorded at rates of 6.80% and 11.6% in the one- and two-level groups, respectively (p = 0.270). Pre- and postoperative PROMs were largely similar between the cohorts; however, patients undergoing one-level discectomy had greater improvement in leg pain, and a significantly greater proportion of these patients achieved MCID for the leg pain visual analog scale score (p < 0.001). At the 1-year clinical follow-up, patients who underwent two-level discectomy had significantly less improvement in leg pain scores with lower achievement of MCID for leg pain improvement than patients undergoing one-level procedures. At the 1-year follow-up, there were no other significant differences in PROMs between the two cohorts. Given these findings, patients should be counseled regarding the anticipated outcomes to better manage expectations. Further studies are warranted to examine the long-term clinical outcomes associated with single- and multilevel MIS discectomy.

Evaluation of surgical characteristics and clinical outcome of 11 patients with thoracic discectomy through transfacet approach

Background: In thoracal disc herniation (TDH) requiring surgery, the size, level, anatomic location, and calcification of the disc are extremely important in the selection of the technique to be applied. Since the thoracic region does not allow spinal cord manipulation, the surgery is difficult and requires experience. A consecutive series of patients who underwent thoracic discectomy through a posterior transfacet approach is presented in this study. Methods: Eleven patients (6 men, and 5 women) underwent surgery at 12 disc levels. The mean age was 53.54 years (range 28-72 years). Patients presented with myelopathy (n = 8, 73%), radiculopathy (n = 7, 64%), back pain (n =10, 91%), and urinary dysfunction (n = 6, 55%). Seven (58%) lateral, 3 (25%) calcified, and 4 (33%) large disc herniations were revealed by preoperative imaging. The mean follow-up period was 21.02 ± 8.04 months (range 6 – 43 months). Results: A posterior transfacet approach was used for all eleven patients with TDH. Thoracic discectomy was performed at T11- 12 (36%) level for 4 patients, and equally at T10- 11 (36%) level for the other 4 patients. A bilateral approach with laminotomy was performed in one patient, and a two-level discectomy was performed in another patient. Unilateral partial laminectomy was added for 3 patients. The average operating time was 146.85 minutes (range 125-220 minutes). The average hospital stay was 4.2 days (range, 2- 13 days) while no neurological functional deterioration was observed in any of the patients after surgery. Postoperative 1-month and 6-month ODI scores were found significantly different from preoperative ODI scores in all patients. Conclusions: Thoracal discectomy through the posterior transfacet approach route is a safe and effective technique to achieve adequate decompression without requiring instrumented fusion.

Retrospective Data Analysis of Anterior Cervical Discectomies and Fusion Without Plate and Screws

Abstract Surgical intervention in cervical disease can relieve neurological symptoms and improve life quality. This study aimed to analyse retrospective data of microscope-assisted anterior cervical discectomy and fusion (ACDF) surgeries. The retrospective study was carried out at the ORTO clinic, Rīga, Latvia, from 2013 to 2017. Data from 198 patients were extracted retrospectively. Data on patient gender, age, diagnosis, extent of operation, type of cage and the overall height of the implants were used. Comparative analysis was carried out with the SPSS 22 software. P &lt; 0.05 represented statistical significance. During the study period, 198 elective ACDF were carried out with increasing number of surgeries: 25 cases in 2013, 43 in 2014, 38 in 2015, 44 in 2016, and 48 in 2017. ACDF were significantly more often performed for females (n = 117, 59%) compared to males (n = 81, 41%; p &lt; 0.003). Women were older with an average age of 50 ± 1 years than men (age 46 ± 1; p = 0.007). The mean surgery time was 1.5 ± 1 hours and the mean hospitalisation time was 3 ± 1 days. Four types of cages were used in similar number of operation: Cervios Peek Chronos C (24%), Syncage C (21%), EIT 3D print (29%), Cervios C Peek (26%); p = 0.2, regardless of patient age or gender. Most often, in 98 cases, the overall height of implants was 6–10 mm. The maximal height was 22 mm, where two patients underwent three-level, and one had a four-level discectomy. The most prevalent disc lesion levels were C5/6 and C6/7, followed by C4/5 and C3/4. One- and two-level discectomies were performed in similar numbers: 95 and 81 cases. However, only 20 patients underwent three level and two patients had four level discectomies in 2016 and 2017. Two level discectomy at C5/6, C6/7 was carried out significantly more often for women (55 vs. 26; p = 0.01), and for men 1-level lesion was more common in C6/7; p = 0.04. The overall incidence of cage subsidence was 5.5%, and the highest incidence was 24% when a Syncage C was used. The ACDF appears to be performed increasingly more often, particularly, in females. The most frequent operation was in one or two cervical levels; including level C6/7 in both genders. In the last years, three- and four-level cervical discectomies have become one of the surgical opportunities. Choice of cage was not influenced by patient gender and age, while cage biophysical and biochemical properties may influence the choice.

131. Primary single-level lumbar discectomy/decompression at a free-standing ambulatory surgery center (ASC) vs a hospital-owned outpatient facility (HOPD): an analysis of 90-day outcomes and costs

BACKGROUND CONTEXT Over the past decade, free-standing ambulatory surgery centers (ASCs) have increasingly grown in numbers in many regions. ASCs are independent of hospitals and are often owned by physicians or unaffiliated management companies. Because ASCs are free-standing, they do not have direct access to hospital inpatient facilities or emergency rooms. Though free-standing ASCs are increasingly utilized for routine elective spine surgeries, no study has evaluated the surgical safety and cost savings associated with performing surgery at a free-standing ASC vs a hospital-owned outpatient facility (HOPD). PURPOSE To evaluate differences in 90-day outcomes and costs associated with primary single-level lumbar discectomy/decompressions performed at a free-standing ASC vs. a HOPD. STUDY DESIGN/SETTING Retrospective review of 2007-2017Q1 Humana Administrative Claims (HAC) database. PATIENT SAMPLE The Humana 2007-2017Q1 Administrative Claims (HAC) dataset of Medicare Advantage and Commercial beneficiaries, was queried using Current Procedural Terminology codes 63030, 63056 and 0275T to identify patients undergoing primary single-level lumbar discectomy/decompressions. Patients undergoing two-level surgery, laminectomies, fusions, revision discectomies and/or deformity surgeries were excluded. Service location codes for hospital outpatient (22) and free-standing ASC (24) were used to define two groups. OUTCOME MEASURES Ninety-day complications, readmissions, emergency department (ED) visits and costs. METHODS Patients undergoing surgery at an ASC were case-control matched to patients undergoing surgery at an HOPD on the basis of age, gender, race, region and Elixhauser Co-morbidity Index (ECI) to reduce any selection bias. Following matching, Chi-square tests were used to assess significant differences in 90-day complications, readmissions, ED visits and costs. RESULTS A total of 1,077 and 10,475 primary single-level discectomy/decompressions were performed in ASCs and HO facilities respectively. Following matching, the two cohorts comprised of 990 patients each. Although 90-day complications (ASC=9.1% vs. HO=10.3%; p=0.362) and readmissions (ASC=4.5% vs HO=5.3%; p=0.466) were lower in ASCs, these were not statistically significant. On average, performing surgery in an ASC vs. HO resulted in significant cost savings of over $2000/case in Medicare Advantage ($5,814 vs. $7,829) and over $3,500/case ($10,116 vs. $13,623) in Commercial beneficiaries. CONCLUSIONS Performing single-level discectomy/decompression surgeries in an ASC, as compared to hospital outpatient facilities, was associated with around $2,000-$3,500 cost savings per case with no significant impact on complication and readmission rates. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

P75. Pathway analysis in spine surgery: a model for evaluating length of stay

BACKGROUND CONTEXT Spine surgeries utilize significant hospital resources, with length of stay (LOS) being a major cost driver. Predicting inpatient hospitalization is essential for the operational success of a hospital. Previous studies identifying pertinent factors that impact LOS in spine surgery are limited. PURPOSE To identify pre-, intra-, and post-operative factors associated with LOS in patients undergoing spine surgery. STUDY DESIGN/SETTING Retrospective review of spine surgery patients at a Canadian tertiary academic teaching hospital. PATIENT SAMPLE A total of 415 spine surgery patients. OUTCOME MEASURES LOS (calculated from the date of surgery to the date of discharge, with no accommodation for partial days). METHODS Institutional research ethics board (IRB) approval was obtained. Patients undergoing surgery by two orthopedic spine surgeons between October 2014 to October 2016 were identified using billing codes. Chart data were extracted on 16 surgical and nonsurgical factors by two independent reviewers. Factors collected included age, sex, BMI, ASA class, insurance claim, transfusion, preop medication use (antidepressant, neuroleptic and narcotic), surgical procedure (sub-grouped into 10 categories: single level transforaminal lumbar interbody fusion (TLIF), 2-level TLIF, discectomy, laminectomy, posterior c-spine, minimally-invasive stabilization, anterior lumbar interbody fusion (ALIF), anterior cervical decompression and fusion (ACDF), major deformity, and other (hematoma, removal of hardware, incision and drainage), Charlson Comorbidity Index, preop hemoglobin, surgical time, initial versus revision surgery, intraop analgesic dose, and LOS. Multiple quasi-poisson regression was used to identify factors associated with LOS. RESULTS There were 378 patients with full data included in the final analysis. Average age of the cohort was 52 years (16.3 sd, range 16-88) and 51% were female. Thirty percent (n=123) of the procedures were 1-level TLIF, while 6% (n=25) were 2-level TLIF. Other prominent procedures included discectomy (18%), laminectomy (15%) and posterior c-spine (7%). The average LOS for the entire cohort was 5.9 ±11.0 days and was right skewed: 58 subjects (14%) had 0 days in hospital and 59 subjects (14%) stayed longer than 1 week. A poisson model was built to predict LOS with surgical procedure while controlling for the other study variables. Compared to patients undergoing one- or two-level laminectomy, those that had single level or two-level discectomy stayed less than half as long (IRR=0.44, 95% CI: [0.24, 0.80]). Posterior c-spine patients (IRR=4.92, 95% CI: [2.92, 8.28]), major deformities (IRR=3.07, 95% CI: [1.85, 5.10]), ACDFs (IRR=2.24, 95% CI: [1.21, 4.15]), and 1-level TLIFs (IRR=1.50, 95%CI: [1.03, 2.16]) all had significantly longer hospital stays. Amongst the other study variables, ASA class 4 patients had a significantly longer stay (IRR=4.3), and patients that received a transfusion also stayed longer (IRR=2.7). All other factors evaluated were not found to be independently predictive of LOS. CONCLUSIONS The LOS within this cohort is strongly correlated with the procedure performed. Medical comorbidities and other factors did not significantly impact LOS except in very ill patients. Future pathway improvement should focus on procedure-specific, post-operative rehabilitation protocols and appropriate pre-operative optimization of severe medical illness. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

Fixation of multiple level anterior cervical disc using cages versus cages and plating

BackgroundCervical disc herniation is a common cause of neck, upper limb, and upper back pain. In severe cases, neurological deficit might occur. It is surgically treated anteriorly or posteriorly, anteriorly through both cervical discectomy and fusion (ACDF) using cages alone or using cages plus plating.ObjectivesWe aimed to evaluate the fusion rate and the clinical outcome of multiple level anterior cervical discectomy followed by cage fusion alone and cage fusion with plate insertion.Materials and methodsIn this prospective comparative study, 33 patients were included. Patients were divided into 2 groups: group A: 19 cases received ACDF and group B: 14 patients had ACDF plus plate fixation. Fusion rate was assessed by radiographs. Clinical outcome was assessed by the visual analog scale (VAS). Overall patients’ satisfaction postoperatively was graded according to Odom’s criteria.ResultsThe rate of fusion was 78.9% of patients in group A and 85.7% of patients in group B. Clinical outcomes were similar in both groups. Patient satisfaction according to Odom’s criteria of outcome grading showed 36.8% of patients had excellent recovery and 31.6% had good recovery in group A. While in group B, 42.9% of patients had excellent recovery and 21.4% had good recovery. The differences between both groups were not statistically significant (P = 0.19).ConclusionsACDF with or without plate fixation in more than two-level cervical discectomies achieves good stability and functional outcome. Addition of anterior cervical plate fixation resulted in a higher fusion rate and reduced cage subsidence than that of cage alone.

Back pain improves significantly following discectomy for lumbar disc herniation

Background ContextAlthough lumbar disc herniation (LDH) classically presents with lower extremity radiculopathy, there are patients who have substantial associated back pain. PurposeThe present study aims to determine if patients with LDH with substantial back pain improve with decompression alone. Study DesignThis is a longitudinal observational cohort study. Patient SamplePatients enrolled in the Quality and Outcomes Database with LDH and a baseline back pain score of ≥5 of 10 who underwent single- or two-level lumbar discectomy only. Outcome MeasuresBack and leg pain scores (0–10), Oswestry Disability Index (ODI), and EuroQoL 5D were measured. MethodsStandard demographic and surgical variables were collected, as well as patient-reported outcomes at baseline and at 3 and 12 months postoperatively. ResultsThe mean age of the cohort was 49.8 years and 1,195 (52.8%) were male. Mean body mass index was 30.1 kg/m2. About half of the patients (1,103, 48.8%) underwent single-level discectomy and the other half (1,159, 51.2%) had two-level discectomy. Average blood loss was 44 cc. Most of the patients (2,217, 98%) were discharged home with routine postoperative care. The average length of stay was 0.53 days. At 3 and 12 months postoperatively, there were statistically significant (p<.000) improvements in back pain (from 7.7 to 2.9 to 3.2), leg pain (from 7.5 to 2.3 to 2.5), and ODI (from 26.2 to 11.6 to 11.2). Patients with a single-level discectomy, compared with patients with a two-level discectomy, had similar improvements in 3- and 12-month back pain, leg pain, and ODI scores. ConclusionsPatients with LDH who have substantial back pain can be counseled to expect improvement in their back pain scores 12 months after a discectomy.

Revision surgeries following artificial disc replacement of cervical spine

ObjectiveWe investigated causes and results of revision surgeries after artificial disc replacement of cervical spine (C-ADR). MethodsTwenty-one patients (mean age: 52.8) who underwent revision surgery after C-ADR and who had a minimum 2-year of follow-up were included into this study. The mean time between the primary and revision surgeries was 21 months. During their primary surgeries, 14 patients underwent single level C-ADR, 2 two-level C-ADR, and 5 two-level hybrid surgery for 16 radiculopathy, 3 myelopathy, and 2 adjacent segment diseases. Causes for revision surgeries were at least one of the followings: 17 poor patient selections, 7 insufficient decompressions, 7 malpositions, 6 subsidences, 3 osteolysis, and 1 postoperative infection. ResultsSixteen patients underwent anterior removal of C-ADR, one-level discectomy and fusion (N = 11), two-level discectomy (N = 3) or one-level corpectomy (N = 2) and fusion. Three patients of keel type C-ADR with heterotopic ossification underwent posterior laminoforaminotomy and fusion. Two patients underwent combined procedures due to infection or severe subsidence and osteolysis. At the 2-year follow-up, neck (7.3 vs 1.6) and arm (7.0 vs 1.3) visual analog scales and Neck Disability Index score (46.7 vs 16.32) were improved (all, p < 0.05). According to Odom's criteria, 86% of the patients were satisfied and 91% achieved solid fusion. No major complications developed except for transient dysphagia in 6 patients (29%). ConclusionsIn this small case series, revision surgeries provided successful outcomes in failed C-ADR without major complications. Careful patient selection and meticulous surgical techniques are important to avoid disappointing clinical outcome or even failure of C-ADR. Level of evidenceLevel IV, Therapeutic study.

Revision Surgeries following Artificial Disc Replacement of Cervical Spine: Analysis of 21 Cases

Introduction The use of artificial disc replacement of cervical spine (C-ADR) has been advocated to preserve segmental motion and to prevent adjacent segment disease as an alternative to anterior cervical discectomy fusion (ACDF). Previous studies reported satisfactory clinical and radiological outcomes of C-ADR compared with ACDF. However, some patients with C-ADR undergo revision surgeries due to failure of C-ADR, such as persistence or recurrence of symptoms and complications. Therefore, we performed the current study to investigate causes and results of revision surgeries following C-ADR. Material and Methods Twenty-one patients (13 males and 8 females) were treated with revision surgeries for failure of C-ADR and had a minimum 2-year follow-up. Causes for revision surgeries were at least one of the following: 17 poor patient selections (severe spondylosis), 7 insufficient decompressions, 7 malpositions, 6 subsidences, 3 osteolysis, and 1 infection. The mean age was 52.8 years (range, 43–63 years) and mean time to revision surgery was 21 months (range, 4–84 months). During their initial surgeries, 14 patients underwent single-level C-ADR, 2 two-level C-ADR, and 5 two-level hybrid surgery for 16 radiculopathy, 3 myelopathy, and 2 adjacent segment disease. Clinical evaluation was done by neck and arm visual analog scales (VAS) and Neck Disability Index (NDI) score. Fusion status was evaluated by plain radiographs including flexion and extension lateral radiographs. Follow-up measurements were taken before surgery and postoperatively at 1, 3, 6, and 12 months, 24 months as well as at last follow-up. At the 24-month fololow-up, patients' overall satiafaction and final fusion status were evaluated by Odom's criteria and CT scan, respectively. Results Sixteen patients underwent anterior removal of C-ADR (8 MobiC, 4 Discovery, 2 Bryan, 1 Prodisc-C, and 1 Prestige LP), one-level discectomy and fusion with plate ( N = 11), two-level discectomy and fusion with plate ( N = 3) or corpectomy and two-level fusion with plate ( N = 2). Three patients with keel types of C-ADR (2 Prodisc-C and 1 Prestige LP) and extensive heterotopic ossification were treated by laminoforaminotomy with posterior fusion. Two patients (2 Discovery) with kyphosis and severe bone loss due to infection or severe subsidence were treated by combined anterior and posterior approaches. NDI score and neck and arm VAS were improved after revision surgeries at each time point of follow-up. At the 24 months of follow-up, 86% ( N = 18) of the patients was satisfied and 91% ( N = 19) achieved solid fusion. However, 2 patients with pseudoarthrosis did not have sufficient pain to warrant the operative repair of the psuedoarthrosis. No major neurologic and wound complications were developed except transient dysphagia in 6 patients with mean recovery time of 1.7 months (range, 1–4 months). Conclusion Revision surgeries can provide successful outcomes in failure of C-ADR without major neurologic and wound complications. Our results suggest that careful patient selection and meticulous surgical techniques, such as adequate decompression, proper positioning of C-ADR, and preservation of subchondral bone, are important to avoid revision surgeries for failure of C-ADR.

Does plate profile affect postoperative dysphagia following anterior cervical spine surgery?

Dysphagia following anterior cervical spine surgery is a significant problem. The risk factors for such dysphagia have not been established. We examined whether plate profile affected the incidence of dysphagia. This study enrolled 50 consecutive patients undergoing one-level corpectomy or one- or two-level discectomies with plate fixation performed by the same surgeon from 2004 to 2009. The anterior cervical plates used were either the Codman (Johnson and Johnson Professional Inc., Raynham, MA, USA; width 17.58mm, thickness 2.69mm; 27 patients) or the Zephir (Medtronic Sofamor Danek Inc., Memphis, TN, USA; width 15mm, thickness 1.6mm; 23 patients). Dysphagia was assessed via telephone interviews, and was classified as short-term (occurring within 6months postoperatively) or persistent (persisting beyond 6months postoperatively). The overall short-term and persistent dysphagia rates were 20% and 14%, respectively. The short-term and persistent dysphagia rates were 26% and 13% for the Zephir plate, and 14.8% and 14.8% for the Codman plate, and analysis showed that the rates were similar for both types of plate. Age and sex were not found to correlate with dysphagia. In patients undergoing anterior cervical spine surgery with plate fixation, we found that postoperative dysphagia did not correlate with plate profile up to a plate size of 17.58mm wide and 2.69mm thick. Dysphagia occurred at the same incidence in patients with a smaller plate that was 15mm wide and 1.6mm thick.

Comparisons of Two-level Discectomy and Fusion with Cage Alone versus Single-level Corpectomy and Fusion with Plate in the Treatment of Cervical Degenerative Disc Disease.

ObjectiveTo compare the radiologic parameters and clinical outcomes of two-level anterior cervical discectomy and fusion (ACDF) with cage alone versus single-level anterior cervical corpectomy and fusion (ACCF) with plate in the treatment of two-level contiguous cervical degenerative disc disease.MethodsOf all 38 consecutive patients who were included in this study, 22 patients underwent on a two-level contiguous ACDF with cage alone (ACDF-CA group), 16 patients underwent a single-level ACCF with plate (ACCF-P group). We compared following parameters between these two groups; perioperative parameters (hospital stays, blood loss and operation duration), clinical parameters (Japanese Orthopedic Association scores and Odom's criteria) and radiologic parameters segmental height ratio (SHR), segmental lordotic angle (SLA), global lordotic angle (GLA) and fusion rate).ResultsThe amount of operative blood loss in the ACCF-P group was higher than in the ACDF-CA group with statistical significance (p<0.05). Clinical outcomes and fusion rates were similar between groups. The postoperative SHRs in both groups were higher than that of preoperative period with statistical significance; however, these values significantly decreased at the last follow up period. The SLA increased during the immediate postoperative period, and then mild decreased. The values of GLA in both groups did show variable differences according to each time frame.ConclusionThe results of ACDF-CA were comparable with ACCF-P with regard to clinical and radiologic outcomes in contiguous two-level cervical fusion. A two-level ACDF-CA as a treatment modality for two-level contiguous cervical disc disease may be a worthwhile method as an alternative to single-level ACCF-P.

Case Report: Cauda Equina Syndrome Associated With an Interspinous Device

Although postoperative spinal epidural hematoma (SEH) is not uncommon, hematomas that require surgery are rare. Cauda equina syndrome (CES) may be associated with postoperative SEH. In these cases, early recognition and emergency decompression can prevent further damage and better neurologic recovery. A 41-year-old man underwent two-level discectomy with insertion of an interspinous spacer at L3-4 and L4-5 because of low back pain and radiculopathy. Eight hours after the operation, the patient developed CES. MRI revealed SEH compressing posteriorly at the L3-4 level. On emergency decompression and hematoma evacuation, the interspinous spacer had obstructed the laminotomy site at L3-4 completely, blocking drainage to the drain. The patient experienced complete neurologic recovery by 2months followup. Many studies report risk factors for SEH. However, postoperative SEH can also be encountered in patients without these risks. One study reported a critical ratio (preoperative versus postoperative cross-sectional area) correlated with postoperative symptoms, especially in those with CES. The propensity to develop CES is likely dependent on a number of patient-specific factors. Surgeons should be aware that patients without risk factors may develop acute CES. Wider laminotomy (larger than half of the device size) may help to prevent this complication when one uses the compressible type of device, especially in patients with relatively small lamina.

Anterior cervical microdiscectomy: is bone grafting and in-situ fusion with instrumentation required?

Objective. Anterior cervical microdiscectomy is a procedure commonly performed for degenerative cervical spine disease. However, there is still controversy regarding whether a bone graft with rigid instrument fixation is necessary following single- or two-level discectomy. We review the results of surgery in 120 patients following anterior cervical microdiscectomy without fixation over the last 22 years. Methods and materials. Anterior cervical microdiscectomy was performed in 120 patients using the Smith–Robinson approach in those with definite MRI evidence of radicular or spinal cord compression by ‘soft’ or ‘hard’ disc protrusions. Bone grafting and instrumentation was not done in any of the patients because there was no demonstrable instability of the cervical spine on radiography. Results. Out of the 100 cases operated by the first author, 95 patients had significant improvement in their symptoms and all returned to their normal employment. Four patients required repeat surgery with bone grafting and instrumentation. Of the 20 cases operated by the second author, 19 patients had significant improvement in their symptoms and returned to normal activities. One patient required repeat surgery for a residual disc causing brachalgia. Thus, only 3.3% of the patients required bone grafting with instrumentation for segmental kyphosis and resultant radiculopathy. The remaining patients were significantly improved, and during the follow-up period over 22 years have not developed recurrences or worsening of symptoms even though bone grafting and instrumentation was not done. Conclusions. Anterior cervical microdiscectomy without bone grafting and instrumentation is a safe and effective procedure following single- and two-level discectomy for cervical disc disease, with a success rate of 97.7%. Bone grafting and instrumentation in every case following anterior cervical microdiscectomy is questionable and should only be used in a few selected cases with demonstrated instability.

Comparison of anterior cervical fusion after two-level discectomy or single-level corpectomy: sagittal alignment, cervical lordosis, graft collapse, and adjacent-level ossification

Background context Single-level corpectomy and two-level discectomy with anterior cervical plating have been reported to have comparable fusion and complication rates. However, there are few large series that have compared the two for sagittal alignment, cervical lordosis, graft subsidence, and adjacent-level ossification. Purpose To determine the differences between these two procedures for patients with two-level spondylosis by comparing the pre- and postoperative radiographic data. Study design Retrospective review of prospectively collected data in an academic institution. Patient sample Fifty-two with a single-level corpectomy and 45 with a two-level anterior cervical discectomy and fusion (ACDF). Outcome measures Pre- and postoperative radiographic data for sagittal alignment, cervical lordosis, subsidence, and adjacent-level ossification. Methods We retrospectively reviewed the lateral cervical radiographs of patients who had a solid fusion after a single-level cervical corpectomy or a two-level ACDF for the treatment of a degenerative cervical spondylosis by a surgeon at an academic institution. The choice of the operation was dependent on the presence or absence of retrovertebral compression. All patients underwent anterior cervical fusion using fibula strut allograft and variable-angle screw-plate fixation. None had had prior cervical spine surgery. Twenty-five were excluded because of inadequate radiographs and follow-up. There were 52 with a single-level corpectomy and 45 with a two-level ACDF. The following were analyzed: 1) sagittal alignment (modified method of Toyama); 2) cervical lordosis measured by Cobb angles of fusion constructs (fusion Cobb) and C2–C7 (C2–C7 Cobb); 3) graft collapse determined by the subsidence of anterior/posterior body height of fused segments (anterior/posterior subsidence) and the cranial/caudal plate-to-disc distances (cranial/caudal subsidence), and the difference between anterior and posterior body height for the fused levels (anteroposterior [AP] difference); and 4) the severity of ossification at two adjacent levels. Results The mean durations of follow-up were 23.3±6.6 (corpectomy) and 25.7±6.2 (ACDF) months, range 12 to 45 months. There were no significant differences between the two groups in sagittal alignment, cervical lordosis, graft collapse, and adjacent-level ossification. Graft subsidence and loss of cervical lordosis occurred significantly more during the first 6 weeks after surgery (all measurements, p<.0001) than after 6 weeks, with no significant difference between the two groups. Posterior and caudal end plate subsidence significantly progressed after 6 weeks in Group 1 (p=.04, p=.02). The final follow-up Cobb angle positively correlated with preoperative and immediate postoperative Cobb angles (r=0.437, p<.0001; r=0.727, p<.0001), caudal subsidence (r=0.270, p=.008), and the final AP difference (r=0.915, p<.0001) but did not correlate with surgery level, preoperative and final sagittal alignments, anterior/posterior subsidence, and cranial subsidence. Anterior/posterior subsidence was significantly more strongly related with caudal subsidence (r=0.607, p<.0001; r=0.424, p<.0001) than cranial (r=0.277, p=.007; r=0.211, p=.040) but did not correlate with pre- and postoperative fusion Cobb, and preoperative and the last sagittal alignments. Conclusions Our data suggest that the two procedures yield comparable results in terms of sagittal alignment, cervical lordosis, graft subsidence, and adjacent-level ossification. Graft subsidence and loss of cervical lordosis appeared to occur mainly during the first 6 weeks after surgery. Single-level corpectomy and fusion continued to subside at the posterior portion of caudal end plate even after 6 weeks. On the other hand, graft subsidence did not correlate with preoperative and final postoperative sagittal alignments.

Biomechanical analysis of multilevel discectomy and excision of posterior longitudinal ligament: An in vitro study in sheep

This experimental biomechanical study was performed to determine the effects of multilevel anterior cervical discectomy and excision of posterior longitudinal ligament (PLL) to stabilize the cervical spine using an in vitro animal model. Fifty fresh cadaveric C3-C6 sheep spine specimens were divided into five experimental groups: Group A was the control group; Group B, one-level discectomy; Group C, two- level discectomy, Group D, three-level discectomy, and Group E, three-level discectomy and excision of PLL, respectively. The specimens were subjected to non-destructive loads cycled from zero to five Newton-meter for flexion, extension, right and left lateral bending, and axial rotation on an electrohydraulic test machine. Load displacement curves were obtained via collected data using strain gauges. The values were obtained for all five groups, statistical differences were determined respectively (P<0.05, ANOVA). One-level discectomy was less stable than the control group, two-level discectomy was less stable than one-level discectomy and three-level discectomy was less stable than two-level discectomy, respectively (P<0.05). Excision of PLL did not seem to affect stability (P>0.05). Our data suggested that cervical discectomy decreases stability of sheep spine pieces.

Anterior cervical fusion with interbody cage containing β-tricalcium phosphate augmented with plate fixation: a prospective randomized study with 2-year follow-up

A variety of bone graft substitutes, interbody cages, and anterior plates have been used in cervical interbody fusion, but no controlled study was conducted on the clinical performance of beta-tricalcium phosphate (beta-TCP) and the effect of supplemented anterior plate fixation. The objective of this prospective, randomized clinical study was to evaluate the effectiveness of implanting interbody fusion cage containing beta-TCP for the treatment of cervical radiculopathy and/or myelopathy, and the fusion rates and outcomes in patients with or without randomly assigned plate fixation. Sixty-two patients with cervical radiculopathy and/or myelopathy due to soft disc herniation or spondylosis were treated with one- or two-level discectomy and fusion with interbody cages containing beta-TCP. They were randomly assigned to receive supplemented anterior plate (n = 33) or not (n = 29). The patients were followed up for 2 years postoperatively. The radiological and clinical outcomes were assessed during a 2-year follow-up. The results showed that the fusion rate (75.0%) 3 months after surgery in patients treated without anterior cervical plating was significantly lower than that (97.9%) with plate fixation (P < 0.05), but successful bone fusion was achieved in all patients of both groups at 6-month follow-up assessment. Patients treated without anterior plate fixation had 11 of 52 (19.2%) cage subsidence at last follow-up. No difference (P > 0.05) was found regarding improvement in spinal curvature as well as neck and arm pain, and recovery rate of JOA score at all time intervals between the two groups. Based on the findings of this study, interbody fusion cage containing beta-TCP following one- or two-level discectomy proved to be an effective treatment for cervical spondylotic radiculopathy and/or myelopathy. Supplemented anterior plate fixation can promote interbody fusion and prevent cage subsidence but do not improve the 2-year outcome when compared with those treated without anterior plate fixation.

Biomechanical comparison of two-level cervical locking posterior screw/rod and hook/rod techniques

Background context Locking posterior instrumentation in the cervical spine can be attached using 1) pedicle screws, 2) lateral mass screws, or 3) laminar hooks. This order of options is in order of decreasing technical difficulty and decreasing depth of fixation, and is thought to be in order of decreasing stability. Purpose We sought to determine whether substantially different biomechanical stability can be achieved in a two-level construct using pedicle screws, lateral mass screws, or laminar hooks. Secondarily, we sought to quantify the differential and additional stability provided by an anterior plate. Study design In vitro biomechanical flexibility experiment comparing three different posterior constructs for stabilizing the cervical spine after three-column injury. Methods Twenty-one human cadaveric cervical spines were divided into three groups. Group 1 received lateral mass screws at C5 and C6 and pedicle screws at C7; Group 2 received lateral mass screws at C5 and C6 and laminar hooks at C7; Group 3 received pedicle screws at C5, C6, and C7. Specimens were nondestructively tested intact, after a three-column two-level injury, after posterior C5–C7 rod fixation, after two-level discectomy and anterior plating, and after removing posterior fixation. Angular motion was recorded during flexion, extension, lateral bending, and axial rotation. Posterior hardware was subsequently failed by dorsal loading. Results Laminar hooks performed well in resisting flexion and extension but were less effective in resisting lateral bending and axial rotation, allowing greater range of motion (ROM) than screw constructs and allowing a significantly greater percentage of the two-level ROM to occur across the hook level than the screw level (p<.03). Adding an anterior plate significantly improved stability in all three groups. With combined hardware, Group 3 resisted axial rotation significantly worse than the other groups. Posterior instrumentation resisted lateral bending significantly better than anterior plating in all groups (p<.04) and resisted flexion and axial rotation significantly better than anterior plating in most cases. Standard deviation of the ROM was greater with anterior than with posterior fixation. There was no significant difference among groups in resistance to failure (p=.74). Conclusions Individual pedicle screws are known to outperform lateral mass screws in terms of pullout resistance, but they offered no apparent advantage in terms of construct stability or failure of whole constructs. Larger standard deviations in anterior fixation imply more variability in the quality of fixation. In most loading modes, laminar hooks provided similar stability to lateral mass screws or pedicle screws; caudal laminar hooks are therefore an acceptable alternative posteriorly. Posterior two-level fixation is less variable and slightly more stable than anterior fixation. Combined instrumentation is significantly more stable than either anterior or posterior alone.

POSTERIOR ENDOSCOPIC DISCECTOMY USING ENDOSCOPIC LUMBAR DISCECTOMY SYSTEM (ELDS)

Characteristics of endoscopic lumbar discectomy system (ELDS) developed in Japan were introduced, and the first 50 cases were clinically evaluated. Patients included: 4 cases of double disc herniationat two levels; 1 cranially and 3 caudally migrated discs; 3 spinal canal stenosis; 1 synovial cyst; and 3 persistent ring apophysis. In 4 central disc herniation cases, 1 case was approached bilaterally and other 3 cases unilaterally. Using a step-dilator system, targeting inter-laminar space was exposed and a tubular retractor either of 16 or 18 mm diameter was inserted through the paravertebral muscle. A 30° endoscope of 3 mm diameter was installed to a tubular retractor. Partial laminectomy and resection of ligamentum flavum were performed using microsurgical instruments, followed by medial retraction of the symptomatic nerve root and incision of the herniated disc. Average surgery time was 119 minutes and estimated blood loss was 49.1 gm. Patients left their bed at 1.9 days post-operative and average hospital-stay was 11.5 days. Recovery ratio of the Japanese Orthopedic Association (JOA) score was 80.7%. Average visual analog pain scale at the first day post-operative was 2.9 cm and CRP at the 7th day was 0.4 mg/dl. Adjacent two-level discectomy was possible with one midline skin incision. Coexistence of severe lumbar spinal canal stenosis was most technically demanding pathology. ELDS provided brightened and magnified surgery field. This can be an effective assistant for minimally invasive lumbar disc surgery.

Adjacent Two-Level Lumbar Discectomy

A retrospective outcomes study. To examine the outcome following adjacent two-level lumbar discectomy using both surgeon-based evaluation criteria and validated patient-based quality of life instrument (SF-36). Lumbar discectomies have documented success rates between 49% and 98% for single-level procedures. However, no prior study has specifically examined the outcome following adjacent two-level lumbar discectomy in a large series of patients. This study analyzed 55 patients with a minimum 2-year follow-up. All patients underwent adjacent two-level lumbar discectomy for radicular pain attributable to nerve root impingement at the corresponding levels. The patients were divided into two diagnostic groups based on their preoperative radiographic studies. Patients with two-level adjacent posterolateral lumbar disc herniations without concomitant osseous degenerative changes at the same levels constituted Group 1 (22 patients). Patients with associated osseous degenerative changes at the same levels made up Group 2 (33 patients). The patients' clinical outcome was assessed using the MacNab classification and SF-36 questionnaire. The average duration of follow-up was 41 months (range 24-96 months). The group consisted of 35 males and 20 females with average age of 49 years (range 19-82 years). Excellent results were observed in 49%, good in 20%, fair in 15%, and poor in 16%. However, patients in Group 1 have 86% excellent/good results, whereas patients in Group 2 have 57% excellent/good results. Overall, 15% of the patients required reoperation and subsequent spinal fusion. Analysis of the SF-36 scores revealed significant differences based on patient's diagnostic grouping as well. Patients in Group 1 have physical and mental summary scores comparable with age- and sex-adjusted population norms and significantly higher than those in Group 2 (P < 0.01). Two-level discectomy is an effective treatment with clinical outcome comparable with single-level discectomy. Patients with posterolateral disc herniations and definitive radiculopathy without osseous degenerative changes at the same levels have better clinical outcome and quality of life scores compared with those patients having concomitant degenerative arthritis at the same levels. Patients having two-level discectomy may be at increased risk of requiring subsequent lumbar fusion compared with those with single-level discectomy.

Partial Corpectomy for Cervical Spondylosis

A retrospective review was performed of a single surgeon's experience with partial corpectomy over a 9-year period. The measures evaluated included fusion rate, complications, and neurologic symptoms. To demonstrate the safety and efficacy of partial corpectomy for multilevel cervical spondylosis. Strategies for the surgical management of cervical spondylosis have included laminectomy, multilevel corpectomy, and multilevel discectomy. All have significant disadvantages, including high nonunion rates and late deformity. A procedure incorporating multilevel discectomy, partial corpectomy, strut graft, and plating is described. By removal of the anterior two thirds of the intervening vertebral body, visualization of the interface between the dura and the disc or PLL is enhanced, and osteophytes can be easily removed. Fusion rates are improved. All partial corpectomy cases with a 2-year follow-up evaluation managed by the senior author for multilevel cervical spondylosis from 1991 to June 1999 were reviewed for the number of levels decompressed, graft source, use of plating, fusion success, and neurologic status. Most of the patients (n = 97) were managed with two-level discectomies, with 42 requiring treatment of three levels and 5 requiring treatment of four or more levels. Allograft was used in 60%. The remainder received iliac crest bone graft. The majority (81%) were plated. Of the cases with 2-year follow-up evaluation, the fusion rate was 95.8%, independent of the number of levels fused. Among the 11% who had continued problems, most had improved. Nonunions were higher in smokers. Partial corpectomy is an effective strategy for treating multilevel cervical disc disease. It is associated with a high fusion rate. In addition, partial corpectomy facilitates a complete decompression by providing excellent visualization of the dural interface.