Postoperative Complications of Surgery for Cervical Spondylotic Myelopathy with and Without Athetoid Cerebral Palsy.

STUDY DESIGN: Retrospective cohort study. OBJECTIVES: With the aging of the Japanese population, patients with athetoid cerebral palsy (ACP) are getting older, and the rate of surgery for CSM is increasing in ACP patients. However, postoperative complications of such surgery among adult patients with ACP have not been reported yet. We investigated postoperative complications of surgery for CSM with ACP and compared them with those of surgery for CSM without ACP using a national inpatient database of Japan. METHODS: Using the Diagnosis Procedure Combination database, we identified 61382 patients who underwent surgery for CSM from July 2010 to March 2018. We examined patient backgrounds, surgical procedures, and type of hospital, and a 4:1 propensity score matching was performed to compare the outcomes between the non-ACP and ACP groups. RESULTS: There were 60 847 patients without ACP and 535 patients with ACP. The mean age was 68.5 years in the non-ACP group and 55 years in the ACP group. The percentages of patients who underwent fusion surgery were 21.6% and 68.8% in the non-ACP and ACP groups, respectively. The 4:1 propensity score matching selected 1858 in the non-ACP group and 465 in the ACP group. The ACP group was more likely to have postoperative urinary tract infection (.4% vs 2.8%, P < .001), postoperative pneumonia (.4% vs 2.4%, P < .001), and 90-day readmission for reoperation (1.9% vs 4.3%, P = .003). CONCLUSIONS: We found that ACP patients were more vulnerable to postoperative complications and reoperation after CSM than non-ACP patients.

Does surgical site infection affect patient-reported outcomes after spinal surgery? A multicenter cohort study.

BACKGROUND: Surgical site infections are common in spinal surgeries. It is uncertain whether outcomes in spine surgery patients with vs. without surgical site infection are equivalent. Therefore, we assessed the effects of surgical site infection on postoperative patient-reported outcomes. METHODS: We enrolled patients who underwent elective spine surgery at 12 hospitals between April 2017 and February 2020. We collected data regarding the patients' backgrounds, operative factors, and incidence of surgical site infection. Data for patient-reported outcomes, namely numerical rating scale, Neck Disability Index/Oswestry Disability Index, EuroQol Five-Dimensional questionnaire, and 12-Item Short-Form Health Survey scores, were obtained preoperatively and 1 year postoperatively. We divided the patients into with and without surgical site infection groups. Multivariate logistic regression analyses were performed to identify the risk factors for surgical site infection. Using propensity score matching, we obtained matched surgical site infection-negative and -positive groups. Student's t-test was used for comparisons of continuous variables, and Pearson's chi-square test was used to compare categorical variables between the two matched groups and two unmatched groups. RESULTS: We enrolled 8861 patients in this study; 74 (0.8 %) developed surgical site infections. Cervical spine surgery and American Society of Anesthesiologists physical status classification ≥3 were identified as risk factors; microendoscopy was identified as a protective factor. Using propensity score matching, we compared surgical site infection-positive and -negative groups (74 in each group). No significant difference was found in postoperative pain or dysesthesia of the lower back, buttock, leg, and plantar area between the groups. When comparing preoperative with postoperative pain and dysesthesia, statistically significant improvement was observed for both variables in both groups (p < 0.01 for all variables). No significant differences were observed in postoperative outcomes between the matched surgical site infection-positive and -negative groups. CONCLUSIONS: Patients with surgical site infections had comparable postoperative outcomes to those without surgical site infections.

Impact of body mass index on outcomes after lumbar spine surgery.

The impact of body mass index (BMI) on outcomes after lumbar spine surgery is currently unknown. Previous studies have reported conflicting evidence for patients with high BMI, while little research has been conducted on outcomes for underweight patients. This study aims to examine the impact of BMI on outcomes after lumbar spine surgery. This prospective cohort study enrolled 5622 patients; of which, 194, 5027, and 401 were in the low (< 18.5 kg/m2), normal (18.5-30), and high (≥ 30) BMI groups, respectively. Pain was assessed via the numerical pain rating scale (NPRS) for the lower back, buttock, leg, and plantar area. Quality of life was assessed via the EuroQol 5 Dimension (EQ-5D) and Oswestry Disability Index (ODI). Inverse probability weighting with propensity scores was used to adjust patient demographics and clinical characteristics between the groups. After adjustment, the 1-year postoperative scores differed significantly between groups in terms of leg pain. The proportion of patients who achieved a 50% decrease in postoperative NPRS score for leg pain was also significantly different. Obese patients reported less improvement in leg pain after lumbar spine surgery. The outcomes of patients with low BMI were not inferior to those of patients with normal BMI.

Adaptation and Limitations of painDETECT Questionnaire Score Approach Before and After Posterior Cervical Decompression Surgery.

BACKGROUND: The painDETECT questionnaire (PDQ) is one of the available screening tools for neuropathic pain (NeP), with a cut-off score of 13. This study aimed to investigate changes in PDQ scores in patients undergoing posterior cervical decompression surgery for degenerative cervical myelopathy (DCM). METHODS: Patients with DCM undergoing cervical laminoplasty or laminectomy with posterior fusion were recruited. They were asked to complete a booklet questionnaire including PDQ and Numerical Rating Scales (NRS) for pain at baseline and one year after surgery. Patients with a preoperative PDQ score ≥13 were further investigated. RESULTS: A total of 131 patients (mean age = 70.1 years; 77 male and 54 female) were analyzed. After posterior cervical decompression surgery for DCM, mean PDQ scores decreased from 8.93 to 7.28 (P = 0.008) in all patients. Of the 35 patients (27%) with preoperative PDQ scores ≥13, mean PDQ changed from 18.83 to 12.09 (P < 0.001). Comparing the NeP improved group (17 patients with postoperative PDQ scores ≤12) with the NeP residual group (18 patients with postoperative PDQ scores ≥13), the NeP improved group showed less preoperative neck pain (2.8 vs. 4.4, P = 0.043) compared to the NeP residual group. There was no difference in the postoperative satisfaction rate between the two groups. CONCLUSIONS: Approximately 30% of patients exhibited preoperative PDQ scores ≥13, and about half of these patients demonstrated improvements to below to the cut-off value for NeP after posterior cervical decompression surgery. The PDQ score change was relatively associated with preoperative neck pain.

Predictors for hemostatic thrombin-gelatin matrix usage in spine surgery: a multicenter observational study.

STUDY DESIGN: A prospective cohort study. OBJECTIVES: Thrombin-gelatin matrix (TGM) is a rapid and potent hemostatic agent, but it has some limitations, including the cost and its preparation time. The purpose of this study was to investigate the current trend in the use of TGM and to identify the predictors for TGM usage in order to ensure its proper use and optimized resource allocation. METHODS: A total of 5520 patients who underwent spine surgery in a multicenter study group within a year were included in the study. The demographic factors and the surgical factors including spinal levels operated, emergency surgery, reoperation, approach, durotomy, instrumented fixation, interbody fusion, osteotomy, and microendoscopy-assistance were investigated. TGM usage and whether it was routine or unplanned use for uncontrolled bleeding were also checked. A multivariate logistic regression analysis was used to identify predictors for unplanned use of TGM. RESULTS: Intraoperative TGM was used in 1934 cases (35.0%), among which 714 were unplanned (12.9%). Predictors of unplanned TGM use were female gender (adjusted odds ratio [OR]: 1.21, 95% confidence interval [CI]: 1.02-1.43, p = 0.03), ASA grade ≥ 2 (OR: 1.34, 95% CI: 1.04-1.72, p = 0.02), cervical spine (OR: 1.55, 95% CI: 1.24-1.94, p < 0.001), tumor (OR: 2.02, 95% CI: 1.34-3.03, p < 0.001), posterior approach (OR: 1.66, 95% CI: 1.26-2.18, p < 0.001), durotomy (OR: 1.65, 95% CI: 1.24-2.20, p < 0.001), instrumentation (OR: 1.30, 1.03-1.63, p = 0.02), osteotomy (OR: 5.00, 2.76-9.05, p < 0.001), and microendoscopy (OR: 2.24, 1.84-2.73, p < 0.001). CONCLUSIONS: Many of the predictors for unplanned TGM use have been previously reported as risk factors for intraoperative massive hemorrhaging and blood transfusion. However, other newly revealed factors can be predictors of bleeding that is technically challenging to control. While routine usage of TGM in these cases will require further justification, these novel findings are valuable for implementing preoperative precautions and optimizing resource allocation.

Does Surgical Treatment Affect the Degree of Anxiety or Depression in Patients With Degenerative Cervical Myelopathy?

STUDY DESIGN: Retrospective cohort study. OBJECTIVES: Preoperative mental state has been reported as one of the factors affecting the surgical outcomes of spine surgery, but few studies have examined in detail how patients' mental state is affected by spine surgery. The purpose of this study was to investigate using the Hospital Anxiety and Depression Scale (HADS) whether surgery improves preoperative depression and anxiety in patients with degenerative cervical myelopathy. METHODS: We investigated patient-reported outcomes (Mental Component Summary, Physical Component Summary of SF-12 Health Survey, and EQ-5D, Neck Disability Index, JOACMEQ, satisfaction with treatment) and HADS one year after surgery, comparing them before and after surgery between April 2017 and February 2020. Among the cases diagnosed as preoperative anxiety and depression, we additionally compared the patient-reported outcomes based on the presence or absence of postoperative improvement in mental state, having also investigated the correlation between patient-reported outcomes and HADS for sub-analysis. RESULTS: Among the 99 patients eligible for inclusion in the present study, we found that patient-reported outcomes and the HADS scores improved significantly after surgery. There was a moderate correlation between the amount of change in HADS-D score before and after surgery and the amount of change in NDI (moderate, r = .41), NRS of neck (moderate, r = .46), and JOACMEQ (cervical spine function; moderate, r = .43, upper extremity function; moderate, r = .41, QOL; moderate, r = .41). CONCLUSIONS: We found that surgical treatment for patients with degenerative cervical myelopathy may improve postoperative anxiety and depression as well as other patient-reported outcomes.

RSPO2 defines a distinct undifferentiated progenitor in the tendon/ligament and suppresses ectopic ossification.

Ectopic endochondral ossification in the tendon/ligament is caused by repetitive mechanical overload or inflammation. Tendon stem/progenitor cells (TSPCs) contribute to tissue repair, and some express lubricin [proteoglycan 4 (PRG4)]. However, the mechanisms of ectopic ossification and association of TSPCs are not yet known. Here, we investigated the characteristics of Prg4-positive (+) cells and identified that R-spondin 2 (RSPO2), a WNT activator, is specifically expressed in a distinct Prg4+ TSPC cluster. The Rspo2+ cluster was characterized as mostly undifferentiated, and RSPO2 overexpression suppressed ectopic ossification in a mouse Achilles tendon puncture model via chondrogenic differentiation suppression. RSPO2 expression levels in patients with ossification of the posterior longitudinal ligament were lower than those in spondylosis patients, and RSPO2 protein suppressed chondrogenic differentiation of human ligament cells. RSPO2 was induced by inflammatory stimulation and mechanical loading via nuclear factor κB. Rspo2+ cells may contribute to tendon/ligament homeostasis under pathogenic conditions.

Association Between Preoperative Neuropathic Pain and Patient Reported Outcome Measures After Cervical Spinal Cord Decompression Surgery.

STUDY DESIGN: A prospective observational study. OBJECTIVE: To evaluate the impact on surgical outcomes of preoperative neuropathic pain (NeP) assessed by the painDETECT questionnaire (PDQ) administered to participants undergoing cervical decompression surgery for degenerative cervical myelopathy (DCM). METHODS: Participating patients were separated into the Non-NeP group (preoperative PDQ score ≤ 12), and NeP group (score ≥ 13). They were asked to complete a booklet questionnaire, including NRS for pain, the Short Form-12 for PCS and MCS, EQ-5D, NDI, and COMI-Neck, at baseline and 1 year after surgery. The JOA score for DCM and radiological changes were also evaluated. Propensity scores were used for the generalized linear model to adjust the patients' backgrounds. RESULTS: Of the 116 patients recruited, 105 completed the one-year follow-up. In this study, 31 (29.5%) and 74 (70.5%) patients in the NeP and non-NeP groups, respectively, were compared. Except for the higher female ratio in the NeP group (64.6% vs 33.2%, P = .009), preoperative demographic data and surgical factors were not significantly different between both groups. The NeP group showed greater neck/arm/hand NRS scores and worse pre- and postoperative NDI/EQ-5D/COMI-Neck scores at baseline and 1 year after surgery, but this was not significant in the MCS/PCS and JOA scores. Change scores of neck/arm/hand NRS scores and MCS/PCS/NDI/EQ-5D/COMI-Neck scores were not significant between both groups. CONCLUSIONS: The preoperative NeP, assessed by PDQ, was observed in approximately 30% of patients with DCM who underwent decompression surgery. The presence of NeP was associated with worse pre- and postoperative NDI/EQ-5D/COMI-Neck scores.

Effect of diabetes on patient-reported outcome measures at one year after laminoplasty for cervical spondylotic myelopathy.

Although patients with diabetes reportedly have more peripheral neuropathy, the impacts of diabetes on postoperative recovery in pain and patient-reported outcome measures (PROMs) after laminoplasty for cervical spondylotic myelopathy (CSM) is not well characterized. The authors aimed to elucidate the effects of diabetes on neck/arm/hand/leg/foot pain and PROMs after laminoplasty CSM. The authors retrospectively reviewed 339 patients (82 with diabetes and 257 without) who underwent laminoplasty between C3 and C7 in 11 hospitals during April 2017 -October 2019. Preoperative Numerical Rating Scale (NRS) scores in all five areas, the Short Form-12 Mental Component Summary, Euro quality of life 5-dimension, Neck Disability Index, and the Core Outcome Measures Index-Neck) were comparable between the groups. The between-group differences were also not significant in NRS scores and PROMs one year after surgery. The change score of NRS hand pain was larger in the diabetic group than the nondiabetic group. The diabetic group showed worse preoperative score but greater improvement in the Short Form-12 Physical Component Summary than the nondiabetic group, following comparable score one year after surgery. These data indicated that the preoperative presence of diabetes, at least, did not adversely affect pain or PROMs one year after laminoplasty for CSM.

Treatment of restenosis after lumbar decompression surgery: decompression versus decompression and fusion.

OBJECTIVE: The aim of this study was to compare perioperative complications and postoperative outcomes between patients with lumbar recurrent stenosis without lumbar instability and radiculopathy who underwent decompression surgery and those who underwent decompression with fusion surgery. METHODS: For this retrospective study, the authors identified 2606 consecutive patients who underwent posterior surgery for lumbar spinal canal stenosis at eight affiliated hospitals between April 2017 and June 2019. Among these patients, those with a history of prior decompression surgery and central canal restenosis with cauda equina syndrome were included in the study. Those patients with instability or radiculopathy were excluded. The patients were divided between the decompression group and decompression with fusion group. The demographic characteristics, numerical rating scale score for low-back pain, incidence rates of lower-extremity pain and lower-extremity numbness, Oswestry Disability Index score, 3-level EQ-5D score, and patient satisfaction rate were compared between the two groups using the Fisher's exact probability test for nominal variables and the Student t-test for continuous variables, with p < 0.05 as the level of statistical significance. RESULTS: Forty-six patients met the inclusion criteria (35 males and 11 females; 19 patients underwent decompression and 27 decompression and fusion; mean ± SD age 72.5 ± 8.8 years; mean ± SD follow-up 18.8 ± 6.0 months). Demographic data and perioperative complication rates were similar. The percentages of patients who achieved the minimal clinically important differences for patient-reported outcomes or satisfaction rate at 1 year were similar. CONCLUSIONS: Among patients with central canal stenosis who underwent revision, the short-term outcomes of the patients who underwent decompression were comparable to those of the patients who underwent decompression and fusion. Decompression surgery may be effective for patients without instability or radiculopathy.

Comparison between microendoscopic laminectomy and open posterior decompression surgery for single-level lumbar spinal stenosis: a multicenter retrospective cohort study.

BACKGROUND: Microendoscopic laminectomy (MEL), in which a 16-mm tubular retractor with an internal scope is used, has shown excellent surgical results for patients with lumbar spinal canal stenosis. However, no reports have directly compared MEL with open laminectomy. This study aimed to elucidate patient-reported outcomes (PROs) and perioperative complications in patients undergoing MEL versus open laminectomy. METHODS: This is a multicenter retrospective cohort study of prospectively registered patients who underwent lumbar spinal surgery at one of the six high-volume spine centers between April 2017 and September 2018. A total of 258 patients who underwent single posterior lumbar decompression at L4/L5 were enrolled in the study. With regard to demographic data, we prospectively used chart sheets to evaluate the diagnosis, operative procedure, operation time, estimated blood loss, and complications. The follow-up period was 1-year. PROs included a numerical rating scale (NRS) for lower back pain and leg pain, the Oswestry Disability Index (ODI), EuroQol 5 Dimension (EQ-5D), and patient satisfaction with the treatment. RESULTS: Of the 258 patients enrolled, 252 (97%) completed the 1-year follow-up. Of the 252, 130 underwent MEL (MEL group) and 122 underwent open decompression (open group). The MEL group required a significantly shorter operating time and sustained lesser intraoperative blood loss compared with the open group. The MEL group showed shorter length of postoperative hospitalization than the open group. The overall complication rate was similar (8.2% in the MEL group versus 7.7% in the open group), and the revision rate did not significantly differ. As for PROs, both preoperative and postoperative values did not significantly differ between the two groups. However, the satisfaction rate was higher in the MEL group (74%) than in the open group (53%) (p = 0.02). CONCLUSIONS: MEL required a significantly shorter operating time and resulted in lesser intraoperative blood loss compared with laminectomy. Postoperative PROs and complication rates were not significantly different between the procedures, although MEL demonstrated a better satisfaction rate.

Pelvic incidence change on the operating table.

PURPOSE: While a change in the pelvic incidence (PI) after long spine fusion surgery has been reported, no studies have examined the change in the PI on the operating table. The present study examined the PI-change on the operating table and elucidated the patients' background characteristics associated with this phenomenon. METHODS: This study included patients who underwent lumbar posterior spine surgery and had radiographs taken in a full-standing position preoperatively and a pelvic lateral radiograph in the prone position in the operative room. The patients with PI-change on the operating table (PICOT; PICOT group) and without PICOT (control group) were compared for their background characteristics and preoperative radiographic parameters. RESULTS: There were 128 eligible patients (62 males, 66 females) with a mean age (± standard deviation) of 69.9 ± 11.7 (range: 25-93) years old. Sixteen patients (12.5%) showed a decrease in the PI > 10°, which indicated placement in the PICOT group. The preoperative lumbar lordosis (LL) and PI-LL in the PICOT group were significantly worse than those in the control group (LL: 20.8 ± 16.6 vs. 30.6 ± 16.2, p = 0.0251, PI-LL: 33.9 ± 19.0 vs. 17.3 ± 14.8, p < 0.0001). The PICOT group had a higher proportion of patients who underwent fusion surgery than the control group, but the difference was not significant (62.5% vs. 44.6%, p = 0.1799). CONCLUSION: A decreased PI was observed in some patients who underwent lumbar posterior surgery on the operating table before surgery. Patients with a PI decrease on the operating table had a significantly worse preoperative global alignment than those without such a decrease. LEVEL OF EVIDENCE I: Diagnostic: individual cross-sectional studies with the consistently applied reference standard and blinding.

Divergence in chondrogenic potential between in vitro and in vivo of adipose- and synovial-stem cells from mouse and human.

BACKGROUND: Somatic stem cell transplantation has been performed for cartilage injury, but the reparative mechanisms are still conflicting. The chondrogenic potential of stem cells are thought as promising features for cartilage therapy; however, the correlation between their potential for chondrogenesis in vitro and in vivo remains undefined. The purpose of this study was to investigate the intrinsic chondrogenic condition depends on cell types and explore an indicator to select useful stem cells for cartilage regeneration. METHODS: The chondrogenic potential of two different stem cell types derived from adipose tissue (ASCs) and synovium (SSCs) of mice and humans was assessed using bone morphogenic protein-2 (BMP2) and transforming growth factor-ß1 (TGFß1). Their in vivo chondrogenic potential was validated through transplantation into a mouse osteochondral defect model. RESULTS: All cell types showed apparent chondrogenesis under the combination of BMP2 and TGFß1 in vitro, as assessed by the formation of proteoglycan- and type 2 collagen (COL2)-rich tissues. However, our results vastly differed with those observed following single stimulation among species and cell types; apparent chondrogenesis of mouse SSCs was observed with supplementation of BMP2 or TGFß1, whereas chondrogenesis of mouse ASCs and human SSCs was observed with supplementation of BMP2 not TGFß1. Human ASCs showed no obvious chondrogenesis following single stimulation. Mouse SSCs showed the formation of hyaline-like cartilage which had less fibrous components (COL1/3) with supplementation of TGFß1. However, human cells developed COL1/3+ tissues with all treatments. Transcriptomic analysis for TGFß receptors and ligands of cells prior to chondrogenic induction did not indicate their distinct reactivity to the TGFß1 or BMP2. In the transplanted site in vivo, mouse SSCs formed hyaline-like cartilage (proteoglycan+/COL2+/COL1-/COL3-) but other cell types mainly formed COL1/3-positive fibrous tissues in line with in vitro reactivity to TGFß1. CONCLUSION: Optimal chondrogenic factors driving chondrogenesis from somatic stem cells are intrinsically distinct among cell types and species. Among them, the response to TGFß1 may possibly represent the fate of stem cells when locally transplanted into cartilage defects.

Microendoscope-Assisted Versus Open Posterior Lumbar Interbody Fusion for Lumbar Degenerative Disease: A Multicenter Retrospective Cohort Study.

Background and objectives: Minimally invasive surgery has become popular for posterior lumbar interbody fusion (PLIF). Microendoscope-assisted PLIF (ME-PLIF) utilizes a microendoscope within a tubular retractor for PLIF procedures; however, there are no published reports that compare Microendoscope-assisted to open PLIF. Here we compare the surgical and clinical outcomes of ME-PLIF with those of open PLIF. Materials and Methods: A total of 155 consecutive patients who underwent single-level PLIF were registered prospectively. Of the 149 patients with a complete set of preoperative data, 72 patients underwent ME-PLIF (ME-group), and 77 underwent open PLIF (open-group). Clinical and radiographic findings collected one year after surgery were compared. Results: Of the 149 patients, 57 patients in ME-group and 58 patients in the open-group were available. The ME-PLIF procedure required a significantly shorter operating time and involved less intraoperative blood loss. Three patients in both groups reported dural tears as intraoperative complications. Three patients in ME-group experienced postoperative complications, compared to two patients in the open-group. The fusion rate in ME-group at one year was lower than that in the open group (p = 0.06). The proportion of patients who were satisfied was significantly higher in the ME-group (p = 0.02). Conclusions: ME-PLIF was associated with equivalent post-surgical outcomes and significantly higher rates of patient satisfaction than the traditional open PLIF procedure. However, the fusion rate after ME-PLIF tended to be lower than that after the traditional open method.

Adverse effects of surgeon performance after a night shift on the incidence of perioperative complications in elective thoracolumbar spine surgery.

BACKGROUND: Decline in cognitive function after night shift has been well described. However, in the field of spine surgery, the effect of surgeons' sleeplessness on patient outcome is unclear. The purpose of this study was to investigate whether the risk of perioperative complications in elective thoracolumbar spine surgery could be higher if the surgeon had been on a night shift prior to the day of surgery. METHODS: We performed a retrospective review of patients who underwent elective posterior thoracolumbar spine surgery, as indicated in medical records, between March 2015 and September 2018. In total, 1189 patients were included and divided into two groups: the post-nighttime (n = 110) and control groups (n = 1079). A post-nighttime case was defined when the operating surgeon was on nighttime duty on the previous night, and other cases were defined as controls. We evaluated the incidence of perioperative complications (surgical site infection, postoperative hematoma, postoperative paralysis, nerve root injury, and dural tear) in both groups. RESULTS: Overall, we found no significant difference in the major or minor perioperative complication rates between the two groups, but according to the type of complication, the incidence rate of dural tear tended to be higher in the post-nighttime group (13.6% vs 8.2%, P = 0.074). Multivariate analysis showed that post-nighttime status was an independent risk factor of dural tear (adjusted odds ratio, 2.02; 95% confidence interval [CI], 1.10-3.70; P = 0.023). After stratification by surgical complexity, post-nighttime status was an independent risk factor of dural tear only in the surgeries of 3 levels or more (adjusted odds ratio, 2.81; 95% CI, 1.18-6.67; P = 0.019). CONCLUSIONS: Post-nighttime status was generally not a risk factor of perioperative complications in elective posterior thoracolumbar spine surgeries, but was an independent risk factor of dural tear, especially in complex cases.

Computer tomography navigation for the transoral anterior release of a complex craniovertebral junction deformity: A report of two cases.

INTRODUCTION: The surgical correction of deformities of the craniovertebral junction (CVJ) remains a challenge due to its complex anatomy. Despite the well-known usefulness of computed tomography (CT) navigation in posterior spinal surgery, it is applied far less frequently in anterior spinal surgery, mainly due to registration difficulties. PRESENTATION OF THE CASE: Case 1 was a 68-year-old female with rheumatoid arthritis, with a complaint of neck pain, motor weakness, and dysesthesia in the upper extremities. Case 2 was a 61-year-old male with Chiari malformation, with a complaint of neck pain and gait disturbance after a fall. Magnetic resonance imaging (MRI) showed severe atlantoaxial dislocation and multilevel cervical spinal cord compression in both patients. Continuous halo traction failed to reduce atlantoaxial dislocation, even under general anesthesia, and they were treated with combined anterior release and posterior decompression and fixation using CT navigation. Occipitocervical assimilation, which was present in both patients, enabled precise registration for navigation. DISCUSSION: The lack of anatomically characteristic landmarks on the vertebral surface makes obtaining accurate registration difficult in anterior CVJ surgery using CT navigation. The remaining mobility in the occipitocervical joint precludes the use of facial or cranial landmarks. However, occipitocervical assimilation, which is not uncommon in patients with CVJ deformities, enables accurate navigation during transoral surgery. CONCLUSION: Transoral anterior release using CT navigation is an effective treatment option for rigid complex CVJ deformities. The accurate identification of the patients' anatomical features such as occipitoatlantal assimilation, is crucial for the conducting accurate preoperative CT-based navigation during transoral surgery.