Interbody Cage Placement Without Plate Supplementation Adjacent to Plated Segments in Multilevel Anterior Cervical Decompression and Fusion.

STUDY DESIGN: A retrospective cohort study. OBJECTIVE: To evaluate the clinical efficacy and safety of hybrid anterior cervical fixation, focusing on stand-alone segments. SUMMARY OF BACKGROUND DATA: In the treatment of multilevel cervical stenosis, the number of segments fixed using a plate is limited by placing an interbody cage without plate supplementation at one end of the surgical segment to reduce long plate-related problems. However, the stand-alone segment may experience cage extrusion, subsidence, cervical alignment deterioration, and nonunion. METHODS: Patients who underwent three-segment or four-segment fixation for cervical degenerative disease and completed one-year follow-up were included in this study. Patients were divided into two groups: a cranial group, with stand-alone segments located at the cranial end adjacent to plated segments, and a caudal group, with stand-alone segments located at the caudal end. Differences in radiographic outcomes between the groups were evaluated. Fusion was defined using dynamic radiographs or computed tomography. To identify factors associated with nonunion in stand-alone segments, multivariable logistic regression analyses were performed. To identify factors associated with cage subsidence, multiple regression analyses were performed. RESULTS: A total of 116 patients (mean age, 59±11 y; 72% male; mean fixed segments, 3.7±0.5 segments) were included in this study. No case showed cage extrusion or plate dislodgement. In stand-alone segments, the fusion rate was significantly lower in the caudal group than in the cranial group (76% vs. 93%, P =0.019). Change in the cervical sagittal vertical axis was worse in the caudal group than in the cranial group (2.7±12.3 mm vs. -2.7±8.1 mm, P =0.006). One caudal group patient required additional surgery because of nonunion at the stand-alone segment. Multivariable logistic regression indicated factors associated with nonunion included the location of the stand-alone segment (caudal end: OR 4.67, 95% CI, 1.29-16.90), larger pre-disk space range of motion (OR 1.15, 95% CI, 1.04-1.27), and lower preoperative disk space height (OR 0.57, 95% CI, 0.37-0.87). Multiple regression analysis indicated that higher cage height and lower pre-disk space height were associated with cage subsidence. CONCLUSION: Hybrid anterior cervical fixation with stand-alone interbody cage placement adjacent to plated segments may avoid long plate-related problems. Our results suggest that the cranial end of the construct may be more suitable for the stand-alone segment than the caudal end.

Risk Factors for Cage Migration Following Lateral Lumbar Interbody Fusion Combined With Posterior Instrumentation: A Multicenter Retrospective Study of 983 Cases.

STUDY DESIGN: A multicenter retrospective study. OBJECTIVE: This study aimed to elucidate the incidence and risk factors of lateral cage migration (LCM) after lateral lumbar interbody fusion (LLIF) combined with posterior instrumentation. SUMMARY OF BACKGROUND DATA: LLIF has recently become a widely accepted procedure for the treatment of lumbar degenerative diseases. Although LLIF complications include vascular, nerve, and abdominal organ injuries, few studies have identified specific risk factors for LCM after LLIF. MATERIALS AND METHODS: Between January 2015 and December 2020, 983 patients with lumbar degenerative diseases or osteoporotic vertebral fractures underwent LLIF combined with posterior instrumentation. The fusion sites were located within the lumbosacral lesions. LCM was defined as a change of >3 mm in the movement of the radiopaque marker on radiographs. The patients were classified into LCM and non-LCM groups. Medical records and preoperative radiographs were also reviewed. The 1:5 nearest-neighbor propensity score matching technique was used to compare both groups, and radiologic parameters, including preoperative disk height (DH), preoperative sagittal disk angle, disk geometry, height variance (cage height minus DH), and endplate injury, were analyzed to identify the factors influencing LCM incidence. RESULTS: There were 16 patients (1.6%) with LCM (10 men and 6 women; mean age 70.1 yr). The Cochran-Armitage trend test showed a linear trend toward an increased rating of LCM with an increasing number of fused segments ( P =0.003), and LCM occurred at the terminal cage-inserted disk level in all patients in the LCM group. After propensity-matched analysis, we identified high DH ( P <0.001), large sagittal disk angle ( P =0.009), round-type disk ( P =0.008), and undersized cage selection ( P <0.001) as risk factors for LCM. CONCLUSION: We identified risk factors for LCM after LLIF combined with posterior instrumentation. To avoid this complication, it is important to select the appropriate cage sizes and enhance posterior fixation for at-risk patients.

Reoperation for Misplaced Pedicle Screws: A Multicenter Retrospective Study.

STUDY DESIGN: A multicenter retrospective analysis. OBJECTIVE: This study aims to investigate reoperation of misplaced pedicle screws (MPSs) after posterior spinal fusion (PSF), focusing on neurological complications. SUMMARY OF BACKGROUND DATA: The management strategy for MPSs and the clinical results after reoperation are poorly defined. MATERIALS AND METHODS: Subjects were 10,754 patients (73,777 pedicle screws) who underwent PSF at 11 hospitals over 15 years. The total number of reoperations for MPS and patient clinical data were obtained from medical records at each hospital. RESULTS: The rate of reoperation for screw misplacement per screw was 0.17%. A total of 69 patients (mean age, 67.4±16.5 yr) underwent reoperation because of 82 MPS. Reasons for reoperation were neurological symptoms (58 patients), contact with vessels (5), suboptimal bone purchase (4), and misplacement recognized during operation (2). Neurological symptoms were the major reason for reoperation in cervical (5/5 screws, 100%) and lumbo-sacral (60/67 screws, 89.6%) regions. Contact with vessels was the major reason for reoperation in the thoracic spine (6/10 screws, 60.0%). We further evaluated 60 MPSs in the lumbo-sacrum necessitating reoperation because of neurological symptoms. The majority of MPSs necessitating reoperation were placed in the lower lumbar spine (43/60 screws, 71.7%). The mean pedicle breach tended to be larger in the incomplete recovery group than in the complete recovery group (6.8±2.4 vs . 5.9±2.2 mm, P =0.146), and the cutoff value resulting in incomplete resolution was 5.0 mm. Multivariate analysis revealed that medial-caudal breaches ( vs . medial breach, odds ratio: 25.8, 95% confidence interval: 2.58-258, P =0.0057) and sensory and motor disturbances ( vs . sensory only, odds ratio: 8.57, 95% confidence interval: 1.30-56.6, P =0.026) were significant factors for incomplete resolution of neurological symptoms. CONCLUSIONS: After reoperation, 70.1% of the patients achieved complete resolution of neurological symptoms. Factors associated with residual neurological symptoms included sensory and motor disturbance, medial-caudal breach, and larger pedicle breach (>5 mm).

Insufficient Recovery From C5 Palsy Following Anterior Cervical Decompression and Fusion.

STUDY DESIGN: Retrospective study. OBJECTIVE: To determine the risk factors for insufficient recovery from C5 palsy (C5P) following anterior cervical decompression and fusion (ADF). SUMMARY OF BACKGROUND DATA: Postoperative C5P is a frequent but unsolved complication following cervical decompression surgery. Although most patients gradually recover, some recover only partially. When we encounter new-onset C5P following ADF, the question that often arises is whether the palsy will sufficiently resolve. METHODS: We retrospectively reviewed consecutive patients who underwent ADF at our institution. We defined C5P as postoperative deterioration of deltoid muscle strength by two or more grades determined by manual muscle testing (MMT). We evaluated the following demographic data: patient factors, surgical factors, and radiological findings. C5P patients were divided into two groups: sufficient recovery (MMT grade≧4) and insufficient recovery (MMT grade < 4). Each parameter was compared between the two groups. RESULTS: Of 839 patients initially included in the study, 57 experienced new-onset C5P (6.8%). At the final follow-up (mean, 55 ±â€Š17 months), 41 patients experienced sufficient recovery, whereas 16 (28%) still exhibited insufficient recovery. Compared with the sufficient recovery group, patients with insufficient recovery exhibited a higher decompression combination score, a larger anterior shift in preoperative cervical sagittal balance, less lordosis of the pre- and postoperative C4/C5 segment, more frequent stenosis at the C3/C4 segment, lower deltoid strength at C5P onset, more frequent co-occurrence of biceps weakness, greater postoperative expansion of the dura mater, and more frequent presence of postoperative T2 high-intensity areas. Multivariate analysis revealed that co-occurrence of biceps muscle weakness, less lordosis at the preoperative C4/C5 segment, and postoperative expansion of the dura mater were independent predictors of insufficient recovery. CONCLUSION: The combination of unfavorable conditions, such as potential spinal cord disorder, cervical malalignment, and excessive expansion of the dura mater after corpectomy, predicts insufficient recovery from C5P.Level of Evidence: 4.

Association Between C5 Palsy and the Anterior Decompression Procedures, Corpectomy and Discectomy.

STUDY DESIGN: This is a retrospective study. OBJECTIVE: The aim was to evaluate the influence of various decompression procedures on the incidence of C5 palsy (C5P). SUMMARY OF BACKGROUND DATA: C5P is a well-known but unsolved complication of cervical spine surgery. Among anterior cervical decompressive procedures, both corpectomy and discectomy are important surgical methods, whose effects on the incidence of C5P are unknown. METHODS: We retrospectively analyzed 818 patients (529 men; mean age: 59.2±11.6 y) who underwent anterior cervical decompression and fusion. The surgical choice to use corpectomy, discectomy, or hybrid decompression was based on standard treatment strategies depending on local compressive pathology and presenting clinical symptoms. We introduced an original "decompression combination score" as a means of quantifying the effects of the procedures on the development of C5P. The scores were based on the relative severity of various risk factors associated with the eventual development of C5P and were assigned as follows: C4 corpectomy, 1 point; C5 corpectomy, 1 point; C3 corpectomy successive to C4 corpectomy, 0.5 point; C6 or C7 corpectomy successive to C5 corpectomy, 0.5 point; C4/5 discectomy, 0.5 point; discectomy at another segment, 0 point. Each patient's decompression combination score was then comprised of the sum of these points. RESULTS: C5P occurred in 55 (47 men, mean age: 65.7±8.7 y) of the 818 (6.7%) patients. A larger number of operated disc segments was significantly associated with C5P. Higher decompression combination score was significantly associated with C5P. Multivariate analysis revealed that male sex, higher decompression combination score, and older age were significant risk factors. CONCLUSIONS: Corpectomy increased the incidence of C5P, while discectomy decreased the risk. The lower incidence of postoperative C5P after discectomy may be because of minimizing tethering effect to the C5 nerve root. As a preventive measure against C5P, corpectomy should be avoided, while discectomy is recommended as much as possible. LEVEL OF EVIDENCE: Levels of Evidence: Step IV-Oxford Center for Evidence-Based Medicine 2011.

Cranial Kyphotic Change After Multilevel Anterior Cervical Corpectomy and Fusion May Lead to Myelopathy Recurrence.

OBJECTIVE: To determine the characteristic alignment change in patients with myelopathy recurrence after multilevel anterior cervical corpectomy and fusion (m-ACCF). METHODS: We analyzed 52 patients who underwent m-ACCF, including 20 who underwent revision surgeries for myelopathy recurrence (R group) and 32 postoperative asymptomatic patients (A group). Classic alignment parameters (cervical lordosis angle, cervical sagittal vertical axis, and fusion area angle and length) and original alignment parameters (α-ß, ß-bone graft [BG], BG-γ, and γ-δ angles) were measured preoperatively, postoperatively, and at follow-up or before revision surgery. The difference in the amount of change in parameters between groups was analyzed. The relationship between distribution of restenotic lesions and characteristic alignment change in the R group was evaluated. RESULTS: Cervical lordosis angle, fusion area angle, and fusion area length in the R group significantly decreased postoperatively compared with the A group (P < 0.01, P < 0.01, and P = 0.04). Compared with the A group, α-ß and ß-BG angles in the R group significantly decreased (P < 0.01), indicating kyphotic change on the cranial side. BG-γ and γ-δ angles in the R group significantly increased (P < 0.01), indicating lordotic change in the caudal fused area. Restenotic lesions significantly increased on the cranial side in the R group (cranial side, 19 levels; caudal side, 5 levels; P < 0.01). CONCLUSIONS: In patients with myelopathy recurrence after m-ACCF, the cranial side has significant kyphosis and the caudal side has lordosis. Moreover, 79.2% of the restenotic lesions were significantly maldistributed on the cranial side. Surgeons should pay close attention to cranial kyphosis inducing myelopathy recurrence after m-ACCF.

Compensatory Mechanisms for Kyphotic Change in the Cervical Spine According to Alignment Analysis of the Cases after Anterior Cervical Corpectomy and Fusion.

BACKGROUND: Compensatory mechanisms for cervical kyphosis are unclear. Few alignment analyses have targeted ongoing cervical kyphosis and detailed the effects of compensatory alignment changes. METHODS: We analyzed the radiographic alignment parameters of 31 patients (21 men and 10 women) with postoperative kyphotic changes after anterior cervical corpectomy and fusion (ACCF) between 2006 and 2015. This analysis included lordotic angle of the fusion area, fusion area length, cervical lordosis angle (CL), O-C7 angle (O-C7a), and cervical sagittal vertical axis (cSVA) as basic parameters and occipito-C2 angle (O-C2a), adjacent cranial angle, adjacent caudal angle, and T1 slope as compensatory parameters at 2 time points after surgery. RESULTS: Alignment analysis revealed that CL was significantly decreased by 5.0 ± 7.7° (P < 0.01) and O-C7a was changed by only -0.2 ± 6.8° (P = 0.75). An inverse correlation was found between ΔCL and ΔO-C2a (ρ = -0.40), with a nearly 1:1 relationship in the scatter diagram. ΔT1 slope had no direct compensatory correlation with ΔCL (P = 0.28) but was strongly correlated with ΔcSVA (ρ = 0.78). The scatter diagram of ΔcSVA and ΔT1 slope showed compensatory relevance and a shifted point to its collapse as the T1 slope lost control of cSVA; thereafter, both parameters incessantly increased, and ΔT1 and ΔcSVA became positive. CONCLUSIONS: When CL decreased after ACCF, ΔO-C2 immediately compensated for the CL loss that could lead to failure to obtain horizontal gaze. If cSVA increased, Δcaudal adjacent angle and ΔT1 slope (extension below the kyphosis) compensated for the horizontal offset translation. The noncompensatory status (ΔcSVA and ΔT1 positive) may necessitate further correction surgery in which the caudal fused level is beyond T1.

Surgical strategies and outcomes for intradural lipomas over the past 20 years.

Intradural lipoma is an extremely rare spinal tumor. The boundary between the spinal cord and the lipoma is usually unclear, with adhesions being firm. Thus, total resection of the tumor is difficult and the neurological prognosis after total resection is poor. Information on the management of this type of tumor is scarce owing to the limited studies that have been conducted and the low sample sizes reported. Here, we report a case and provide a review of the literature on intradural lipomas over the past 20 years. In addition to describing our case, we reviewed reports published in Pubmed and CiNii. The demographic data of the patients included in these studies were extracted and the surgical procedures were assessed, along with their corresponding postoperative outcomes. There were 57 primary cases and 4 cases of recurrence. Among the primary cases, the neurological symptoms were persistent in 54 (95%) after surgery. The postoperative outcomes after excessive (>60% tumor resection) or total resection were significantly poor. In the recurrence cases, the mean period from initial surgery to recurrence was 11 years and all initial surgical procedures involved only partial resection surgery. This report is, to the best of our knowledge, the most exhaustive analysis of cases of intradural lipomas and recurrences. The optimal treatment for lipoma necessitates both partial resection and duraplasty.

Catastrophic Dropped Head Syndrome Requiring Multiple Reconstruction Surgeries after Cervical Laminoplasty.

INTRODUCTION: Dropped head syndrome (DHS) after cervical laminoplasty (LAMP) is a rare complication, and no etiologies or surgical strategies have been reported. We present a patient who developed catastrophic DHS after LAMP despite having preoperative cervical lordosis that is known to be suitable for LAMP. We describe a hypothesis concerning the possible mechanism responsible for the DHS and a surgical strategy for relieving it. CASE REPORT: A 76-year-old woman underwent LAMP for cervical spondylotic myelopathy. She achieved satisfactory improvement of neurological symptoms immediately after surgery. However, her neurological symptoms began to gradually deteriorate. She exhibited a dropped head and complained of difficulty maintaining horizontal gaze. Postoperative images showed a focal cervical kyphotic deformity causing anterior shift of the head, and recurrence of spinal cord compression was observed. She underwent additional surgeries for three times, but none of them restored her to baseline status. Retrospectively, the preoperative loading axis of the head existed anteriorly, and she also had a high T1 slope because of rigid thoracic kyphosis. Her preoperative hyper cervical lordosis was compensation for the global spinal malalignment. After LAMP, in accordance with decreases in her cervical lordosis, her head shifted anteriorly. The abnormal lever arm acting on the neck put further stress on the neck extensors, and the overstretched neck extensors possibly no longer generated enough power to raise the head. Uncompensated very high T1 slope because of marked thoracic kyphosis plus invasion of the posterior extensor mechanism by LAMP may have contributed to her catastrophic DHS development. CONCLUSIONS: In the treatment of cervical myelopathy, posterior decompression alone should be applied carefully to elderly patients with cervical sagittal imbalance even if they have apparent cervical lordosis. Once DHS occurs because of cervical sagittal imbalance, normalization of global spinal balance through corrective osteotomy may be indispensable for a successful outcome.

Pedicle Screw Fluid Sign: An Indication on Magnetic Resonance Imaging of a Deep Infection After Posterior Spinal Instrumentation.

STUDY DESIGN: A single-center case-referent study. OBJECTIVE: To assess whether the "pedicle screw (PS) fluid sign" on magnetic resonance imaging (MRI) can be used to diagnose deep surgical site infection (SSI) after posterior spinal instrumentation (PSI). SUMMARY OF BACKGROUND DATA: MRI is a useful tool for the early diagnosis of a deep SSI. However, the diagnosis is frequently difficult with feverish patients with clear wounds after PSI because of artifacts from the metallic implants. There are no reports on MRI findings that are specific to a deep SSI after PSI. We found that fluid collection outside the head of the PS on an axial MRI scan (PS fluid sign) strongly suggested the possibility of an abscess. METHODS: The SSI group comprised 17 patients with a deep SSI after posterior lumbar spinal instrumentation who had undergone an MRI examination at the onset of the SSI. The non-SSI group comprised 64 patients who had undergone posterior lumbar spinal instrumentation who did not develop an SSI and had an MRI examination within 4 weeks after surgery. The frequency of a positive PS fluid sign was compared between both groups. RESULTS: The PS fluid sign had a sensitivity of 88.2%, specificity of 89.1%, positive predictive value of 68.1%, and negative predictive value of 96.6%. The 2 patients with a false-negative PS fluid sign in the SSI group had an infection at the disk into which the interbody cage had been inserted. Three of the 7 patients with a false-positive PS fluid sign in the non-SSI group had a dural tear during surgery. CONCLUSIONS: The PS fluid sign is a valuable tool for the early diagnosis of a deep SSI. The PS fluid sign is especially useful for diagnosing a deep SSI in difficult cases, such as feverish patients without wound discharge.

Surgical results and complications of anterior decompression and fusion as a revision surgery after initial posterior surgery for cervical myelopathy due to ossification of the posterior longitudinal ligament.

OBJECTIVE Ossification of the posterior longitudinal ligament (OPLL) is a progressive disease. An anterior cervical decompression and fusion (ACDF) procedure for cervical OPLL is theoretically feasible, as the lesion exists anteriorly; however, such a procedure is considered technically demanding and is associated with serious complications. Cervical laminoplasty is reportedly an effective alternative procedure with few complications; it is recognized as a comparatively safe procedure, and has been widely used as an initial surgery for cervical OPLL. After posterior surgery, some patients require revision surgery because of late neurological deterioration due to kyphotic changes in cervical alignment or OPLL progression. Here, the authors retrospectively investigated the surgical results and complications of revision ACDF after initial posterior surgery for OPLL. METHODS This was a single-center, retrospective study. Between 2006 and 2013, 19 consecutive patients with cervical OPLL who underwent revision ACDF at the authors' institution after initial posterior surgery were evaluated. The mean age at the time of revision ACDF was 66 ± 7 years (± SD; range 53-78 years). The mean interval between initial posterior surgery and revision ACDF was 63 ± 53 months (range 3-235 months). RESULTS The mean follow-up period after revision ACDF was 41 ± 26 months (range 24-108 months). Before revision ACDF, the mean maximum thickness of the ossified posterior longitudinal ligament was 7.2 ± 1.5 mm (range 5-10 mm), and the mean C2-7 angle was 1.3° ± 14° (range -40° to 24°). The K-line was plus (OPLL did not exceed the K-line) in 8 patients and minus in 11 (OPLL exceeded the K-line). The mean Japanese Orthopaedic Association score improved from 10 ± 3 (range 3-15) before revision ACDF to 11 ± 4 (range 4-15) at the last follow-up, and the mean improvement rate was 18% ± 18% (range 0%-60%). A total of 16 surgery-related complications developed in 12 patients (63%). The main complication was an intraoperative CSF leak in 8 patients (42%). Neurological function worsened in 5 patients (26%). The deterioration was due to spinal cord herniation through a defective dura mater in 1 patient, unidentified in 1 patient, and C-5 palsy that gradually recovered in 3 patients. Reintubation, delirium, and hoarseness were observed in 1 patient each (5%). No patient required reoperation for reconstruction failure, and all patients eventually had a solid bony fusion. CONCLUSIONS ACDF as revision surgery after initial posterior surgery for cervical myelopathy due to OPLL is associated with a high incidence of intraoperative CSF leakage and an extremely low improvement rate. The authors think that while the use of revision ACDF must be limited, it is indispensable in special cases, such as progressing myelopathy following posterior surgery due to a very large beak-type OPLL that exceeds the K-line. Postoperative OPLL progression and/or kyphotic changes can possibly cause later neurological deterioration. Fusion should be recommended at the initial surgery for many cases of cervical OPLL to prevent such a challenging revision surgery.

Lumbar Spinal Surgery in Patients With Parkinson Disease: A Multicenter Retrospective Study.

STUDY DESIGN: A multicenter, retrospective study. OBJECTIVE: To identify the factors that affect surgery-related complications and to clarify the surgical strategy for treating lumbar disorders in Parkinson disease (PD). SUMMARY OF BACKGROUND DATA: Previous studies have reported a high complication rate for spinal surgery in patients with PD. Because of the limited number of studies, there are no guidelines for spinal surgery for PD patients. METHODS: We retrospectively reviewed the records for 67 PD patients who underwent lumbar spinal surgery. The patients were divided into 3 groups: 12 patients underwent laminectomy (Laminectomy), 24 underwent fusion surgery (Fusion) for lumbar canal stenosis, and 31 underwent corrective surgery for spinal deformity (Deformity). We assessed surgery-related complications in each group. The Cox proportional hazards model was used to identify the factors that predicted surgical failure. RESULTS: The percentages of patients who experienced failure of the initial surgery were 33.3% in the Laminectomy group, 45.8% in the Fusion group, and 67.7% in the Deformity group. The rates of implant failure were high in the Fusion and Deformity groups (33.3% and 38.7%, respectively). The Deformity group had a high rate of postoperative fracture (41.9%). These complications occurred at the most caudal site within a year after surgery and resulted in progression of kyphotic deformity. Multivariate analysis revealed that preoperative lumbar lordosis angle (LL) (per -1 degree) was associated with a failure of the initial surgery (hazard ratio, 1.024; 95% confidence interval, 1.008-1.04; P=0.003). CONCLUSIONS: We have demonstrated that a small preoperative LL increases the risk for failure of the initial surgery. Attaining and maintaining the proper lumbar lordosis with rigid fixation may be necessary in PD patients with a small preoperative LL.

Hybrid Decompression and Fixation Technique Versus Plated 3-Vertebra Corpectomy for 4-Segment Cervical Myelopathy: Analysis of 81 Cases With a Minimum 2-Year Follow-Up.

STUDY DESIGN: A retrospective comparative study. OBJECTIVE: The purpose of this study was to compare the stability and outcomes of a hybrid technique with those of a 3-vertebra corpectomy in the management of 4-segment cervical myelopathy. SUMMARY OF BACKGROUND DATA: Patients with primarily ventral disease and loss of cervical lordosis are considered good candidates for anterior surgery. Cervical corpectomy is commonly performed in patients with multilevel cervical myelopathy. Corpectomies including >3 vertebraes entail an extremely high risk of reconstruction failure. To avoid the need to perform a 3-vertebra corpectomy, we use a hybrid decompression and fixation technique. This hybrid technique is a technique to obtain optimum decompression and fixation in patients with multilevel cervical myelopathy. METHODS: A total of 81 patients with multilevel cervical myelopathy who underwent 4-segment cervical fixation with a minimum 2-year follow-up were included. RESULTS: The hybrid technique involved combining a plated 2-vertebra corpectomy and single-level discectomy with stand-alone cage fixation. This technique was performed in 39 patients, and the plated 3-vertebra corpectomy was performed in 42 patients. Nine patients (21%) who underwent the plated 3-vertebra corpectomy were treated with halo immobilization, but no patient in the hybrid group required this treatment (P=0.002). There were fewer instances of reconstruction failure in the hybrid group than in the 3-vertebra corpectomy group (0% vs. 10%, respectively; P=0.048) and fewer instances of C5 palsy (3% vs. 17%, respectively; P <0.0001). The incidence of postoperative C5 palsy was 25% for C3-C5 corpectomy, 19% for C4-C6 corpectomy, and 11% for C4-C5 corpectomy+C6-C7 discectomy. CONCLUSIONS: The hybrid technique has the following advantages over 3-vertebra corpectomy for 4-segment cervical fixation: a shorter graft bone and plate are required; the fixed segment has greater initial stability; postoperative external immobilization is simplified; and the risk of reconstruction failure and postoperative C5 palsy is reduced markedly.

Anterior corpectomy and fusion to C2 for cervical myelopathy: clinical results and complications.

PURPOSE: Anterior cervical corpectomy and fusion (ACCF) to C2 (ACCF-C2) for multilevel lesions is a challenging procedure that is indicated for massive ossification of the posterior longitudinal ligament (OPLL) extending to C2 or stenosis at the upper cervical region accompanied by kyphosis. However, there is little information on the effectiveness of and complications related to ACCF-C2. The purpose of this study was to investigate the overall surgical results and postoperative complications of ACCF-C2 for cervical myelopathy. METHODS: Sixteen patients who underwent ACCF-C2 for OPLL and cervical spondylotic myelopathy were evaluated. An iliac bone or a fibular strut was grafted using a cervical plate. The mean fusion level was 3.8, and the mean follow-up period was 36 months. Patients' charts, clinical results assessed using the Japanese Orthopedic Association (JOA) scale, and radiographs were retrospectively reviewed. RESULTS: The average preoperative JOA score was 11.5 ± 3.5, and improved significantly to 13.1 ± 3.2 at 24 months after surgery (P < 0.01). The postoperative cervical alignment was significantly improved at the last follow-up (P < 0.05). Seven patients experienced complications, including neurological complications in three, graft-related complications in three, cerebrospinal fluid leakage in two, late retropharyngeal perforation in one, and dysphasia in one. Three of 16 patients experienced upper airway obstruction in this series, and 2 of 473 patients who underwent anterior cervical decompression and fusion at lower levels in the same period (P < 0.001). CONCLUSIONS: ACCF-C2 is effective for massive OPLL and stenosis accompanied by kyphosis. To avoid complications, skilled decompression and bone grafting technique are necessary, and delayed extubation for upper airway obstruction is preferable.

Extremely wide and asymmetric anterior decompression causes postoperative C5 palsy: an analysis of 32 patients with postoperative C5 palsy after anterior cervical decompression and fusion.

STUDY DESIGN: Single-center retrospective study. OBJECTIVE: We examined whether extremely wide and asymmetric anterior decompression causes postoperative C5 palsy. SUMMARY OF BACKGROUND DATA: Postoperative C5 palsy is a complication of cervical decompression surgery. We hypothesized that C5 palsy may be caused by nerve root impairment through extremely wide and asymmetric dural expansion due to unilateral predominant wide anterior decompression with concomitant C4-C5 foraminal stenosis. METHODS: The study included 32 patients with postoperative C5 palsy from a cohort of 459 patients who underwent anterior cervical decompression and fusion at the C4-C5 disc level for cervical myelopathy. The 64 upper extremities were divided into 2 groups according to palsy side (n = 35) or nonpalsy side (n = 29). Also, to correlate radiological findings, 66 consecutive patients who underwent anterior cervical decompression and fusion without postoperative C5 palsy were selected as control. RESULTS: In patients with C5 palsy, the unilateral decompression width on the palsy side was significantly larger than that on the nonpalsy side (8.63 vs. 6.92 mm, P = 0.0003). In addition, the decompression width was significantly larger (15.69 vs. 14.38 mm, P = 0.02), the diameter of the C4-C5 foramen was significantly smaller (2.73 vs. 3.24 mm, P = 0.0008), the anterior spinal cord shift was significantly smaller (0.14 vs. 0.73 mm, P< 0.0001), and significant decompression asymmetry (0.74 vs. 0.89, P = 0.0003) was present in the patients with C5 palsy compared with controls. CONCLUSION: Extremely wide and asymmetric decompression concomitant with pre-existing C4-C5 foraminal stenosis may cause postoperative C5 palsy. Our findings should be valuable for surgeons considering anterior cervical decompression and fusion that includes the C4-C5 level. Surgeons should consider restriction of the decompression width to less than 15 mm and avoiding asymmetric decompression to reduce the incidence of C5 palsy.

Sacral fracture after instrumented lumbosacral fusion: analysis of risk factors from spinopelvic parameters.

STUDY DESIGN: Retrospective comparative study. OBJECTIVE: To examine the incidence and characteristics of key spinopelvic parameters that are correlated with sacral fracture development after lumbosacral fusion. SUMMARY OF BACKGROUND DATA: Sacral fracture is a possible complication of instrumented lumbosacral fusion and this has recently been documented in the literature. Preoperative awareness of risk factors concerning spinopelvic parameters and sacral fracture may aid in surgical planning to prevent its occurrence. METHODS: All patients who underwent instrumented lumbosacral fusion from L2 or above, between 2010 and 2011 at Gakkentoshi Hospital, were included. RESULTS: A total of 116 patients (47 men and 69 women) were evaluated in this study. Average age at surgery was 71 years, and the average follow-up period was 19 months. The average number of fixed segments was 5, and the average time interval between index surgery and sacral fracture development was 42 days. Notably, sacral fractures were identified in 5 patients (4.3%), all of whom were women. We, therefore, compared the 2 groups of female patients (fracture group, n = 5 vs. nonfracture group, n = 64). The fracture group had a substantially higher mean pelvic incidence (PI) than the nonfracture group (72° ± 8° vs. 51° ± 12°, respectively, P < 0.01). The fracture group also had a larger postoperative lumbar lordosis (LL)-PI mismatch than the nonfracture group (-26° ± 7° vs. -7° ± 18°, respectively, P < 0.01). CONCLUSION: The current review of our patients informs appropriate preoperative planning in cases involving lumbosacral fusion for postmenopausal women with a high PI. Surgeons should plan to achieve large increases in LL to restore not only spinopelvic harmony but also to avoid postoperative sacral fracture. For such patients, because it is difficult to consistently achieve a sufficiently large LL, we recommend prophylactic iliosacral fixation to protect the sacrum. LEVEL OF EVIDENCE: 4.

Progressive thoracic myelopathy caused by spinal calcium pyrophosphate crystal deposition because of proximal junctional vertebral compression fracture after lumbopelvic fusion.

PURPOSE: We describe cases presenting with progressive thoracic myelopathy after lumbopelvic fusion attributed to proximal junctional vertebral compression fracture (PJF) followed by spinal calcium pyrophosphate dehydrate (CPPD) crystal deposition. METHODS: The study included six patients, ranging from 62 to 75 years. All patients had been treated previously with lumbopelvic fusion. The mean period from the detection of PJF to the onset of myelopathy was 4.8 months. Notably, five patients demonstrated upper-instrumented vertebra (UIV) collapse. RESULTS: After revision surgery involving decompressive laminectomy and extension of the spinal fusion, all patients experienced significant improvement. Photomicrographs of the resected ligamentum flavum showed CPPD crystals and multinucleated giant cells. CONCLUSIONS: The combination of mechanical stress plus PJF and CPPD crystal deposition followed by a foreign body reaction to the deposited crystals caused myelopathy. Patients with radiographic evidence of PJF, especially UIV collapse, after lumbopelvic fusion should be followed carefully for the emergence of myelopathy.

Risk factors for cage retropulsion after posterior lumbar interbody fusion: analysis of 1070 cases.

STUDY DESIGN: Single-center retrospective study. OBJECTIVE: We examined the risk factors for cage retropulsion after posterior lumbar interbody fusion (PLIF) performed for patients with degenerative lumbar spinal diseases. SUMMARY OF BACKGROUND DATA: Although PLIF is a widely accepted procedure, problems remain regarding perioperative and postoperative complications. There are few reported studies identifying specific risk factors for cage retropulsion, one of the implant-related complications after PLIF, although several case reports have been published. METHODS: Between April 2006 and July 2010, 1070 patients with various degenerative lumbar spinal diseases underwent single- or multilevel PLIF combined with posterolateral fusion, using posterior pedicle screw fixation and box-type cages. Their medical records and preoperative radiographs were reviewed and the factors influencing the incidence of cage retropulsion were analyzed. RESULTS: There were 9 cases of cage retropulsion (7 men and 2 women; mean age, 68.2 yr), and it developed within 2 months after surgery in all cases. Five patients had low back pain or leg pain, 3 of whom required revision surgery. The mean fusion level was 3.9 (range, 2-5); in 6 of the 9 patients, the cage had migrated at L5/S, 2 at L4/5, and 1 at L3/4. All of the cages were inserted at the end disc level of multilevel fusion procedures. The disc heights and ranges of motion were significantly greater in patients with cage retropulsion, and patients with a pear-shaped disc space also showed a higher rate of cage retropulsion. CONCLUSION: These results indicate that PLIF at L5/S, a wide disc space with instability, multilevel fusion surgery, and a pear-shaped disc space on lateral radiographs are risk factors for cage retropulsion. The identification of these risk factors should allow us to avoid this complication, and the use of expandable cages is an effective option for such cases.

Anterior corpectomy with fusion in combination with an anterior cervical plate in the management of ossification of the posterior longitudinal ligament.

STUDY DESIGN: A retrospective study. OBJECTIVE: The aim of this study is to evaluate the safety and efficacy of an anterior cervical plate (ACP) used in combination with anterior corpectomy with fusion (ACF) for cervical ossification of the posterior longitudinal ligament (OPLL). SUMMARY OF BACKGROUND DATA: Consensus is lacking about the most suitable method to treat cervical myelopathy caused by OPLL. The decision to perform an ACF to treat multilevel myelopathy is controversial because of the potential for problems in the grafted bone. METHODS: We evaluated the surgical outcome of ACF combined with insertion of an ACP for treating cervical myelopathy caused by OPLL. The study group comprised 68 patients who were treated from 2006 to 2009 and followed for an average of 29.6 months. We retrospectively reviewed the information in the patients' charts and radiographs. RESULTS: No dislodgement of the grafted bone or implant was observed, and no patient developed infection, esophageal or tracheal lacerations, or rupture. Radiographs showed no evidence of nonunion. The mean preoperative and the final follow-up C2 to C7 lordotic angles were 6.2±9.5 degrees and 9.4±7.6 degrees, respectively. The preoperative and the final follow-up lordotic angles of the fusion area were 2.0±8.1 degrees and 5.9±6.4 degrees, respectively. The average change in fusion area length was a 1.2 mm increase from before to after the operation and a 1.8 mm decrease from after the operation to the final follow-up. The average recovery rate of the Japanese Orthopaedic Association score was 63.0%. The surgical outcome of ACF with an ACP is satisfactory. CONCLUSIONS: Insertion of an ACP is a good solution for preventing problems with the grafted bone after ACF. Our study suggests that the indications for an anterior-only procedure for the management of cervical OPLL can be expanded.

Spinal nerve root herniation into a pseudomeningocele associated with lumbar spondylolysis: a case report.

A 38-year-old man presented with low back pain and sciatica on the left side. Magnetic resonance imaging showed spinal nerve root herniation into a pseudomeningocele associated with lumbar spondylolysis. After closure of the dural defect, the sciatic pain was relieved and subsequently the patient was able to return to work.