Anterior Controllable Antedisplacement Research Articles

Anterior Controllable Antedisplacement and Fusion (ACAF) for Cervical Stenosis Patients With Hyperextension Injury: A Retrospective Study.

Central cord syndrome (CCS) is an incomplete spinal cord injury (SCI) causing severe motor weakness, and timely decompression via surgical intervention facilitates better recovery. Anterior controllable antedisplacement and fusion (ACAF) is a novel decompression technique and achieved satisfactory outcomes in treating cervical degenerated diseases. However, the clinical effects of ACAF on CCS remains unknown. This present study aimed to investigate the clinical outcomes of ACAF for cervical stenosis patients with CCS due to hyperextension injury. This is a retrospective study, and patients who underwent ACAF due to CCS in our institution from July 2021 to December 2022 were enrolled based on the inclusion and exclusion criteria. All patients underwent x-ray, computed tomography (CT), and magnetic resonance imaging (MRI) before and after surgery. The duration of follow-up was at least 12 months. The radiological parameters included associated pathologies, prevertebral hyperintensity (HI), intramedullary signal intensity (ISI), and Torg-Pavlov ratio (TPR). The cervical stability was also evaluated. Neurological function was assessed using the American Spinal Injury Association (ASIA) grading system and Japanese Orthopaedic Association (JOA) score. The Mann-Whitney U test was used to compare the clinical outcomes preoperatively and postoperatively. Finally, 13 patients (7 male and 6 female) with the minimum of 12-month follow-up were finally enrolled in this study, with the mean age of 56.6 ± 12.5 years (range, 39-74 years). There were eight patients suffered CCS due to fall, three due to vehicle accident, and two due to diving injuries. The average delay from injury to surgery was 2.23 days (range, 1-4 days), and the mean duration of follow-up was 16.1 ± 3.5 months. In terms of prevertebral HI and ISI, C4-C6 were the most affected region. In addition, 76.9% (10 of 13) patients were observed to have cervical stenosis indicated by TPR. Associated pathologies were herniated nucleus pulposus (HNP) in five patients, OPLL in three cases, and HNP-osteophyte complexes (HNP-OC) in six patients. At the final follow-up, 13 patients were improved to E. The mean JOA score improved to 15.4 ± 1.0, with the recovery rate of 77.0% ± 12.0%. Two patients experienced postoperative dysphagia, two patients had hoarseness, and one patient suffered postoperative hematoma. ACAF can be a good option for treating CCS patients due to hyperextension injury with underlying cervical spondylosis and stenosis.

Improved Function After Anterior Controllable Antedisplacement and Fusion for Cervical Ossification of Posterior Longitudinal Ligament: A Long-Term Follow-Up.

Anterior controllable antedisplacement and fusion (ACAF) is an emerging surgical approach for treating cervical ossification of the posterior longitudinal ligament (C-OPLL), yet there is limited data on its long-term efficacy and safety. The present study aimed to analyze the short- and long-term postoperative clinical and radiological outcomes and perioperative complications of ACAF for patients with C-OPLL. This was a single-center, retrospective, cohort study, with the mean duration of follow-up of at least 24 months. A total of 111 patients with C-OPLL in our institution from June 2017 to June 2019 were assessed preoperatively and at 3 days, 3, 6, 12, and 24 months postoperatively. The primary outcome was the recovery of neurological function, measured with the Japanese Orthopedic Association (JOA) score. The secondary outcomes included pain, Cobb angle, spinal canal invasion rate, and surgery-related complications. The postoperative JOA score at each follow-up was significantly better than the preoperative JOA score, regardless of preoperative spinal canal invasion rate, K-line, and segment length. The visual analog scale (VAS) score also decreased dramatically 3 days after surgery and was maintained at a low level throughout the follow-up period. Improvements in Cobb angle and invasion rate were observed right after the operation and were maintained for 2 years thereafter. ACAF could achieve satisfactory recovery of neurological function in C-OPLL patients during a follow-up of 24 months, regardless of preoperative spinal canal invasion rate, preoperative K-line, or surgical segment length.

Novel Algorithm for Surgical Management of Cervical Ossification of Posterior Longitudinal Ligament: A Retrospective Cohort Study With 2-Year Follow-Up.

With the development of new technologies, the surgical algorithm for ossification of posterior longitudinal ligament (OPLL) in the cervical spine also needs to be updated. The aim of this study is to elucidate a new surgical classification algorithm to guide the choice of surgical approaches for cervical OPLL based on its location and extent. In this algorithm, anterior controllable antedisplacement and fusion (ACAF) will be used as a new surgical option. This is a single-centered, retrospective, cohort study utilizing a novel algorithm based on the following three criteria: (1) the positional relationship between ossification and uncinate process (UP), (2) the K-line, and (3) the ossification segment for surgical decision-making. Patients diagnosed with cervical OPLL who received surgical intervention guided by the algorithm were included. Patient demographics, Japanese Orthopedic Association (JOA) scores, surgical time, imaging data before and 2 years after surgery, and the occurrence of complications were extracted from the database. Paired t-test was used for intragroup comparison, and one-way ANOVA test was used for the intergroup analyses. Based on this novel algorithm, 15 patients with Type I, 8 patients with Type II a, 2 patients with Type II b1, 5 patients with Type II b2 were included. The decision-making for the surgical techniques used in each patient followed the recommendation of the novel algorithm. The postoperative JOA scores of all types of patients improved significantly (p < 0.05), and the invasion rates of vertebral canal had also been significantly reduced (p < 0.05). In terms of restoring cervical curvature, patients with Type I (receiving ACAF) and Type II b2 (receiving laminectomy with instrumented fusion) benefited more from surgery (p < 0.05). A new algorithm guiding the choice of surgical approach for cervical OPLL was validated in a series of 30 patients. Through this analysis, we obtained on their clinical outcomes and complications. ACAF surgery is an ideal choice for Type I patients, with ossification located between UPs, while for patients with ossification exceeding UPs, it is better to perform anterior cervical corpectomy and fusion or posterior surgery.

Application of the "Klotski Technique" in Cervical Ossification of the Posterior Longitudinal Ligament With En Bloc Type Dura Ossification.

The anterior controllable antedisplacement and fusion (ACAF) technique is a new procedure for the treatment of cervical ossification of the posterior longitudinal ligament (OPLL) that requires management of the disc adjacent to the ossification. This study describes a novel technique to reduce the number of fixed segments, namely, the "Klotski technique." The efficacy of ACAF using the Klotski technique was compared with that of anterior cervical corpectomy and fusion (ACCF) in the treatment of OPLL with en bloc type dural ossification (DO). The clinical data of 25 patients with severe OPLL and en bloc type DO who were treated by the ACAF Klotski technique or ACCF at our hospital from January 2020 to January 2022 were retrospectively analyzed. In the Klotski technique, the number of segments fused within the OPLL is limited. The antedisplacement space was designed according to the shape of the vertebrae-OPLL-DO complex (VODC). Then, the entire VODC was antedisplaced as in Klotski. Neurological function and image examination were assessed preoperatively and postoperatively. Complications associated with surgery were recorded. Patients were followed up for 24-36 months. There were 11 patients who were treated with ACAF and 14 patients who were treated with ACCF. At 2 weeks after surgery, the incidence of neurological deterioration was 21.4% (3 of 14) in the ACCF group and 9.1% (1 of 11) in the ACAF group. The incidence of intraoperative cerebrospinal fluid leakage (CFL) was 35.7% (5 of 14) in the ACCF group and 9.1% (1 of 11) in the ACAF group. The postoperative follow-up JOA scores of the patients in both groups were significantly better than their preoperative JOA scores (p<0.05). The Klotski technique for ACAF is a good option for the treatment of patients with en bloc type OPLL-DO, as it limits the number of fused segments, has a low incidence of CFL and neurologic deficits and is associated with good neurological recovery.

The CT Classification of Multilevel Cervical Ossification of the Posterior Longitudinal Ligament to Guide Hybrid Anterior Controllable Antedisplacement and Fusion vs. Posterior Laminoplasty.

For precise and minimally invasive treatment of ossification of the posterior longitudinal ligament of the cervical spine, the lifting segment is minimized, anterior controllable antedisplacement and fusion (ACAF) was refined and improved. In addition, the development of appropriate surgical procedures for the ossification of each segment was rarely reported. Therefore, this study aimed to compare the efficacy and safety of hybrid anterior controlled antedisplacement fusion (Hybrid ACAF) with laminoplasty for multilevel ossification of the posterior longitudinal ligament (OPLL). Between May 2018 and May 2021, 70 patients with multilevel OPLL were divided into a hybrid ACAF group and a laminoplasty group according to surgical methods. All patients were followed up for at least 1 year. Japanese Orthopaedic Association (JOA) score and recovery rate (JOARR), (VAS, NDI) score and C2-C7 Cobb angle, the sagittal vertical axis of the neck (SVA), and complications (cerebrospinal fluid leakage, C5 paralysis, etc.) were compared between the two groups by t test or non-parametric test. The operation time of hybrid ACAF was longer. C5 paralysis and axial pain were more common in the laminoplasty group, while dysphagia and hoarseness were more common in the hybrid ACAF group. At the last follow-up, the hybrid ACAF group had better recovery and maintenance of cervical lordosis and sagittal plane balance and a higher JOA score and recovery rate than the laminoplasty group. Hybrid ACAF can reduce the number of vertebral bodies and expand the decompression range, which is safe, effective, and tailored to local conditions. Compared with laminoplasty, hybrid ACAF is a precise alternative for patients with OPLL.

A Novel “De-tension”-guided Anterior Decompression Strategy—Thoracic Anterior Controllable Antedisplacement Fusion (TACAF) for Multilevel Ossification of Posterior Longitudinal Ligament in Thoracic Spine: A Retrospective Study with at Least 2-Year Follow-Up

To propose a novel surgical strategy-thoracic anterior controllable antedisplacement fusion (TACAF) to treat multilevel thoracic ossification of the posterior longitudinal ligament (mT-OPLL), and investigate its safety and efficacy. Between January 2019 and December 2021, a total of 49 patients with thoracic myelopathy due to mT-OPLL surgically treated with TACAF were retrospectively reviewed. Patients' demographic data, radiologic parameters, and surgery-related complications, modified Japanese Orthopedic Association (mJOA) and visual analog scale (VAS) scores, thoracic kyphosis (TK), kyphosis angle in fusion area (FSK), thoracic curvature, spinal cord curvature, and curvature of curved rod in surgical region, diameter, and area of the spinal cord at the most compressed level were included. All patients acquired satisfactory recovery of neurologic function and overall complication rate was low at the final follow up. The mean mJOA of the laminectomy+TACAF and Full Lamina Preservation+TACAF groups, respectively, was 3.74 ± 2.05, 3.67 ± 1.95 before surgery, and 9.97 ± 0.83, 9.80 ± 0.68 at the final followed up, with the recovery rate of 84.26% ± 14.20%, 82.79% ± 10.35%, as to VAS Scores. The mean FSK was 34.50 ± 4.46,35.33 ± 3.44 before surgery, and was restored to 20.97 ± 5.70, 22.93 ± 6.34 at the final followed up respectively, as to mean TK (P < 0.05). Spinal cord curvature was improved from 34.12 ± 3.59, 33.93 ± 3.45 before surgery to 19.47 ± 3.53, 18.80 ± 3.17 at the final follow-up respectively, as to thoracic curvature (P < 0.05). In addition, the area and diameter of the spinal cord was also significantly improved at the final follow up (all P < 0.05). The curvature of the thoracic pulp and thoracic vertebra is closely related to the curvature of the rod. There was no statistically significant difference in the incidence of the pelvis and the slope value of the sacrum. This strategy provides a novel solution for the treatment of mT-OPLL with favorable recovery of neurological function, the tension of spinal cord, and fewer complications.

Biomechanical Comparison of Anterior Cervical Corpectomy Decompression and Fusion, Anterior Cervical Discectomy and Fusion, and Anterior Controllable Antedisplacement and Fusion in the Surgical Treatment of Multilevel Cervical Spondylotic Myelopathy: A Finite Element Analysis.

Multilevel cervical spondylotic myelopathy poses significant challenges in selecting optimal surgical approaches, warranting a comprehensive understanding of their biomechanical impacts. Given the lack of consensus regarding the most effective technique, this study aims to fill this critical knowledge gap by rigorously assessing and comparing the biomechanical properties of three distinct surgical interventions, including anterior controllable antedisplacement and fusion (ACAF), anterior cervical corpectomy decompression and fusion (ACCF), and anterior cervical discectomy and fusion (ACDF). The study offers pivotal insights to enhance treatment precision and patient outcomes. The construction of the cervical spine model involved a detailed process using CT data, specialized software (Mimics, Geomagic Studio, and Hypermesh) and material properties obtained from prior studies. Surgical instruments were modeled (titanium mesh, anterior cervical plate, interbody cage, and self-tapping screws) to simulate three surgical approaches: ACAF, ACCF, and ACDF, each with specific procedures replicating clinical protocols. A 75-N follower load with 2 Nm was applied to simulate biomechanical effects. The range of motion decreased more after surgery for ACAF and ACDF than for ACCF, especially in flexion and lateral bending. ACCF have higher stress peaks in the fixation system than those of ACAF and ACDF, especially in flexion. The maximum von Mises stresses of the bone-screw interfaces at C3 of ACCF were higher than those of ACAF and ACDF. The maximum von Mises stresses of the bone-screw interfaces at C6 of ACDF were much higher than those of ACAF and ACCF. The maximum von Mises stresses of the grafts of ACCF and ACAF were much higher than those of ACDF. The maximum von Mises stresses of the endplate of ACCF were much higher than those of ACAF and ACDF. The ACAF and ACDF models demonstrated superior cervical reconstruction stability over the ACCF model. ACAF exhibited lower risks of internal fixation failure and cage subsidence compared to ACCF, making it a promising approach. However, while ACAF revealed improved stability over ACCF, higher rates of subsidence and internal fixation failure persisted compared to ACDF, suggesting the need for further exploration of ACAF's long-term efficacy and potential improvements in clinical outcomes.

Anterior controllable antedisplacement and fusion as revision surgery for the treatment of OPLL after anterior and posterior decompression: A case report

Background: In cases of cervical ossification of the posterior longitudinal ligament (OPLL), when initial anterior or posterior decompression fails to yield satisfactory results, the alternative approach is often chosen for revision surgery. Nevertheless, there is a lack of reported information regarding the treatment and prognosis of patients with complex OPLL who have undergone both anterior and posterior decompression but experienced relapse. Case presentation: A 79-year-old male patient presented with numbness, weakness, and muscle atrophy in the right upper extremity, along with weakness in the right lower extremity. Initial assessment on admission revealed a Japanese Orthopaedic Association (JOA) score of 7. The patient previously underwent anterior cervical discectomy and fusion (ACDF) 25 years ago for spinal stenosis, followed by posterior laminectomy as revision surgery. After experiencing recurrent symptoms following a fall one year ago, the patient underwent a second revision surgery using the anterior controllable antedisplacement and fusion (ACAF) technique which led to symptom improvement, and resulted in a postoperative JOA score of 14 at 3 months of follow-up. Conclusions: Treatment of OPLL patients with symptom recurrence after traditional anterior and posterior decompression is challenging. ACAF offers a viable solution for managing this complex case.

Significance of O-Arm Assisted Anterior Controllable Antedisplacement and Fusion Surgery in Treatment of Cervical Ossification of Posterior Longitudinal Ligament

Anterior controllable antedisplacement and fusion (ACAF) surgery for cervical OPLL is commonly used in clinical practice and has shown promising results. Nonetheless, precise slotting and lifting are the most critical procedures in ACAF surgery to avoid several unique and dangerous problems, such as residual ossification and incomplete lifting. C-arm intraoperative imaging can help with traditional cervical surgery but not with the precise slotting and lifting operation in ACAF surgery. Fifty-five patients admitted to our department with cervical OPLL were retrospectively enrolled. Given the selection of intraoperative imaging technique, patients were divided into the C-arm group and O-arm group. The operation time, intraoperative blood loss, hospital stay, Japanese Orthopaedic Association score, Oswestry Disability Index score, visual analog scale score, slotting grade, lifting grade, and complications were recorded and analyzed. At the final follow-up, all patients acquired satisfactory improvement of neurologic function. Patients in the O-arm group, on the other hand, had a better neurologic state 6 months after surgery and at the final follow-up than those in the C-arm group. Furthermore, slotting and lifting grade were considerably higher in the O-arm group than in the C-arm group. No severe complications were encountered in both groups. O-arm assisted ACAF can achieve accurate slotting and lifting, which might effectively reduce the occurrence of complications and is worthy of clinical application.

The effect of K-line classification in different cervical dynamic position on surgical outcomes in patients with ossification of the posterior longitudinal ligament after anterior controllable antedisplacement and fusion.

PurposeTo investigate whether the K-line classification in different cervical dynamic position of patients with Ossification of the Posterior Longitudinal Ligament (OPLL) affects clinical outcome after Anterior Controllable Antedisplacement and Fusion (ACAF) surgery.MethodsA total of 93 patients who suffered from cervical spondylosis caused by OPLL underwent ACAF surgery between June 2015 and December 2017 in a single institution. Neutral, neck-flexed and neck-extended cervical radiographs were obtained from every patient. Subsequently they were classified into K-line (+) and K-line (−) with reference to the K-line classification criteria. Clinical outcomes were assessed by the JOA score, improvement rate (IR) and visual analogue scale (VAS). Radiological assessment included Cobb angle and occupation ratio (OR) of OPLL. Correlations between the long-term surgical outcomes and classification of K-line in different dynamic position were analyzed by one-way analysis of variance.ResultsSignificant improvements were shown in all postoperative clinical and radiographic assessments (P < 0.05). There were no differences in IR, Cobb angle and VAS among flexion K-line (−), flexion K-line (+), extension K-line (−) and extension K-line (+) at the 2-year follow-up (P > 0.05). However, the OR of extension K-line (−) (16.13% ± 11.58%) was higher than that of extension K-line (+) (9.00% ± 10.27%) and flexion K-line (+) subgroup (9.47% ± 9.97%) (P < 0.05).ConclusionThe ACAF procedure has shown satisfactory surgical outcomes in various K-line classifications in different dynamic position.

Cervical Anatomical Landmarks Indicate the Amount of Vertebra Resection during ACAF Surgery: A Semi-Quantitative Anatomical Parameter Study on Imaging Data.

ObjectiveWith the innovation and development of cervical spine surgical procedures, there is currently a lack of new and reliable data on cervical anatomical landmarks. The purpose of this study is to measure the CT data of the cervical vertebrae of healthy volunteers, so as to make up for the missing part of the measured value of cervical vertebra bone markers, and provide data support for the safety and accuracy of anterior controllable antedisplacement and fusion (ACAF) surgery.MethodsFrom January 2019 to January 2020, the cervical computed tomography (CT) scan image data of volunteers in Changhai Hospital and Zhabei Hospital were randomly selected. The radiological parameters included three parameters were measured in the upper lamina plane. a: the distance from the anterior edge of the vertebral body to the anterior edge of the bilateral uncinate joint; c1: the sagittal diameter of the vertebral body; and d: the distance between the anterior edge of the uncinate joint. Three parameters were measured in the pedicle plane. b: the vertical distance from the anterior edge of the vertebral body to the junction line between the two lateral processes; c2: the sagittal diameter of the vertebral body; e: the transverse diameter of the vertebral body; and f: the sagittal diameter of the vertebral canal. The correlation ratios were calculated: a/c1, b/c2, a/f, b/f, d/e. The data between the two groups were compared by independent sample t‐test.ResultsFinally, 51 patients were included in this study, 18 males and 33 females, with an average age of 47.9 years (21–72 years). The maximum values of seven parameters measured were all at C7. The minimum b value was at C5, and the minimum f value was at C4. The minimum values of the other five parameters were all at C3, and there was an increasing relationship from C3 to C7 (P < 0.05). There was significant difference between male and female with regard to c1, c2, e and d values (P < 0.05). No significant differences were observed between men and women regard to the ratio of related parameters (a/c1, b/c2, a/f, b/f, d/e).ConclusionsAnatomical consideration of this area is useful to estimate amount of vertebral body resection when performing the bony cut made in ACAF surgery; however, pre‐operative examinations with appropriate radiographic analysis are also recommended.

Anterior controllable antedisplacement and fusion: quantitative analysis of a single surgeon's learning experience

BACKGROUND CONTEXTAnterior controllable antedisplacement and fusion (ACAF) is a novel surgical technique for the treatment of ossification of the posterior longitudinal ligament (OPLL) but the surgical learning curve for this technique has not been previously characterized. PURPOSEThe aim of this study was to quantify a surgeon's learning curve for ACAF and the effect of surgeon experience on postoperative outcomes. STUDY DESIGNProspective study of a single institution and single surgeon experience with ACAF surgery. PATIENT SAMPLEA total of 70 consecutive patients with OPLL undergoing ACAF surgery by a single, non-ACAF trained surgeon between 2017 and 2020 were analyzed. OUTCOME MEASURESIntraoperative and postoperative outcomes (blood loss, operative time, errors of surgical procedure, length of hospital stay, Japanese Orthopedic Association (JOA) scoring system, and surgical complications) were assessed. METHODSWe prospectively reviewed the first 70 ACAF procedures between 2017 and 2020 performed by a single, non-ACAF trained surgeon. The function relationship between the operative time and case number was fitted using a locally weighted scatterplot smoothing (LOESS) plot. Spearman's correlation analysis was performed to determine factors affecting the operative time. The operative time-related learning curve for ACAF was established and difficulty of each procedure was assessed using a cumulative sum (CUSUM) model. The association between the specific errors of surgical procedures and surgeon experience was further analyzed. A modified CUSUM model was also used to establish the surgical procedure-related learning curve, and thus whether these two learning curves matched with each other was observed. Postoperative outcomes in relation to surgeon experience was compared using a Wilcoxon rank sum test and Chi-squared test. RESULTSOperative time presented a specific pattern of fewer patient-dependent changes as the case number increased. Spearman's correlation analysis showed the operative time was more affected by the case number (r=-0.73) than the complexity of condition and number of levels hoisted. The operative time-related CUSUM model identified the early (first 29 cases) and late phase (late 41 cases) of the learning process, which was also confirmed by a modified CUSUM model based on surgical procedure. The critical point of the CUSUM model for bilateral osteotomies was at case number 29, and time reduction after the early phase was approximately 34 minutes. Length of hospital stay and blood loss were less during the late phase than during the early phase (p<.05). Although no significant difference was observed in postoperative JOA scores between two phases, patients in the late phase obtained higher recovery rates of neurologic function than those in the early phase (p<.01). There was significant difference in the number of specific errors between the two phases (p=.02). There were no significant differences in overall complication rates between two phases, but a higher incidence of certain complications caused by specific errors was observed in the early phase (p=.02), including CSF leakage, C5 palsy and incomplete decompression. CONCLUSIONSWe described, for the first time, a detailed learning curve for ACAF surgery. About 29 cases were needed to achieve mastery of ACAF. Once mastered, the surgeon could deal with various OPLL presentations in a universal way regardless of condition complexity and number of surgical levels. Bilateral osteotomies were the most difficult part of ACAF and produced the greatest reduction in time after mastery. We found a close association between specific errors of surgical procedure for ACAF and surgeon experience. Furthermore, certain complications caused by these errors should be on the alert during the early phase of learning ACAF, including CSF leakage, C5 palsy and incomplete decompression.

Anatomical Evaluation of Spinal Nerve and Cervical Intervertebral Foramina in Anterior Controllable Antedisplacement and Fusion Surgery: A Cadaveric and Radiologic Study.

ObjectiveTo achieve the anatomical evaluation of spinal nerve and cervical intervertebral foramina in anterior controllable antedisplacement and fusion (ACAF) surgery, a novel surgical technique with the wider decompression, through a cadaveric and radiologic study.MethodsRadiographic data of consecutive 47 patients (21 by ACAF and 26 by anterior cervical corpectomy and fusion [ACCF]) who have accepted surgery for treatment of cervical ossification of the posterior longitudinal ligament(OPLL) and stenosis from March 2017 to March 2018 were retrospectively reviewed and compared between an ACAF group and ACCF group. Three postoperative radiographic parameters were evaluated: the decompression width and the satisfaction rate of decompression at the entrance zone of intervertebral foramina on computed tomography (CT), and the transverse diameter of spinal cord in the decompression levels on magnetic resonance imaging (MRI). In the anatomic study, three fresh cadaveric spines (death within 3 months) undergoing ACAF surgery were also studied. Four anatomic parameters were evaluated: the width of groove, the distance between the bilateral origins of ventral rootlets, the length of ventral rootlet from their origin to the intervertebral foramina, the descending angle of ventral rootlet.ResultsThe groove created in ACAF surgery included the bilateral origins of ventral rootlets. The rootlets tended to be vertical from the rostral to the caudal direction as their takeoff points from the central thecal sac became higher and farther away from their corresponding intervertebral foramina gradually. No differences were identified between left and right in terms of the length of ventral rootlet from the origin to the intervertebral foramina and the descending angle of ventral rootlet. The decompression width was significantly greater in ACAF group (19.2 ± 1.2 vs 14.7 ± 1.2, 21.3 ± 2.2 vs 15.4 ± 0.9, 21.5 ± 2.1 vs 15.7 ± 1.0, 21.9 ± 1.6 vs 15.9 ± 0.8, from C3 to C6). The satisfactory rate of decompression at the entrance zone of intervertebral foramina tended to be better in the left side in ACAF group (significant differences were identified in the left side at C3/4, C4/5, C6/7 level, and in the right side at C4/5 level when compared with ACCF). And decompression width was significantly greater than the transverse diameter of spinal cord in ACAF group. Comparatively, there existed no significant difference in the ACCF group besides the C5 level.ConclusionACAF can decompress the entrance zone of intervertebral foramina effectively and its decompression width includes the origins and massive running part of bilateral ventral rootlets. Due to its wider decompression range, ACAF can be used as a revision strategy for the patients with failed ACCF.

An open-label randomized multi-Centre study to evaluate anterior controllable Antedisplacement and fusion versus posterior Laminoplasty in patients with cervical ossification of the posterior longitudinal ligament: study design and analysis plan (STAR)

BackgroundIn treating patients with cervical ossification of the posterior longitudinal ligament (COPLL), a novel surgery technique - anterior controllable antedisplacement and fusion (ACAF) suggested promising clinical benefits in recent exploratory studies.MethodsThis is a multicentre, randomized, open-label, parallel-group, active controlled trial that will compare the clinical benefits of ACAF versus conventional posterior laminoplasty (LAMP) in severe COPLL patients. A total of 164 patients will be enrolled and randomized in a 1:1 ratio to either ACAF or LAMP group. The primary efficacy measure is cervical- Japanese Orthopaedic Association (C-JOA) recovery rate at 12 months post operation, which is to be derived by Hirabayashi’s method from JOA data (range, 0 [worst] to 17 [normal condition]). Other important secondary efficacy endpoints include visual analogue scale (VAS) pain score (range, 0 [no pain] to 10 [most severe]), 10-item neck disability index (NDI, a total range of 0 to 50 points, the highest index the worst) and 6-level Nurick disability grade (range, 0 [mild] to 5 [severe]). Safety endpoints including adverse events, perioperative complications, and adverse events of special interest will also be assessed in this study. Full analysis set for baseline and efficacy data analyses according to the intention-to-treat principle will be established as the primary analysis population. Analysis of covariance (ANCOVA) will be used to analyze the C-JOA recovery rate, with random stratification factors (if appropriate) and the treatment group as fixed factors, and the baseline level of C-JOA score as covariate.DiscussionThis study is designed to demonstrate the clinical benefits of ACAF as compared to conventional LAMP in COPLL patients. It will provide clinical evidence that the novel surgery technique – ACAF might be more favorable in treating patients with severe cervical ossification of the posterior longitudinal ligament. (Words: 290).Trial registrationClinicalTrials.gov number, NCT04968028.

Anterior Controllable Antedisplacement and Fusion (ACAF) Technique for the Treatment of Multilevel Cervical Spondylotic Myelopathy With Spinal Stenosis (MCSMSS): A Retrospective Study of 54 Cases.

Retrospective study. To investigate the clinical effect of anterior controllable antedisplacement and fusion (ACAF) technique for the treatment of multilevel cervical spondylotic myelopathy with spinal stenosis (MCSMSS), compared with hybrid decompression fixation (HDF). A retrospective analysis of 94 cases with MCSMSS was carried out. Fifty-four patients were treated with ACAF, whereas 40 patients were treated with HDF. The operation time, intraoperative blood loss, postoperative complications, Japanese Orthopedic Association score, Neck Disability Index score, parameters at axial computed tomography, cervical curvature and the Kang grade were compared between 2 groups. The patients were followed up for 12-17 (15.6±1.6) months. Compared with HDF, ACAF group achieved better decompression according to computed tomography measurement and Kang grade (P<0.05), and recovered to a greater cervical Cobb angle (P<0.05). However, Japanese Orthopedic Association score and Neck Disability Index showed no significant difference 1 year after surgery (P>0.05). In addition, ACAF presented longer operation time (P<0.05) and similar intraoperative blood loss (P>0.05), compared with HDF. In terms of complications, ACAF produced less incidences of cerebrospinal fluid leakage, implant complication, epidural hematoma, and C5 palsy compared with HDF. ACAF is an effective method for the treatment of MCSMSS. In comparison to HDF, ACAF has the advantages of more sufficient decompression, more satisfactory cervical curvature, and lower incidence rates of complications.

Comparison of the surgeries for the ossification of the posterior longitudinal ligament-related cervical spondylosis: A PRISMA-compliant network meta-analysis and literature review.

Objective:We designed and performed a network meta-analysis to compare the clinical outcomes among the 5 surgeries—anterior cervical corpectomy and fusion (ACCF), anterior controllable antedisplacement fusion (ACAF), laminoplasty (LP), laminectomy (LC), and posterior decompression with instrumented fusion (PDF)—for patients with cervical spondylosis related to the ossification of the posterior longitudinal ligament (OPLL).Methods:Databases, including PubMed, EMBASE, Cochrane Library, Google Scholar, and Web of Science (firstly available-2019) were selected for literature search. We performed a network meta-analysis with the included studies. A Newcastle-Ottawa scale was employed to assess the study quality of the included studies.Results:Total 23 studies with 1516 patients were included in our analysis. We found that ACCF achieved the most improvement in the Japanese Orthopaedic Association Scores and excellent and good recovery rate, ACAF achieved the best improvement of the improvement rate and lordosis. LP got the best operative time and blood loss.Conclusions:Our results suggested that both anterior (ACCF and ACAF) and posterior (LP, LC, and PDF) procedures have their strengths and weaknesses. Clinicians need to select the most appropriate surgery with a comprehensive consideration of the clinical condition of each patient with OPLL-related cervical spondylosis.

Commentary: Microsurgical Anterior Controllable Antedisplacement Fusion to Treat Cervical Ossified Posterior Longitudinal Ligament: 2-Dimensional Operative Video.

Commentary: Microsurgical Anterior Controllable Antedisplacement Fusion to Treat Cervical Ossified Posterior Longitudinal Ligament: 2-Dimensional Operative Video.

Exclusion of Ossified Ligaments Behind C2 Vertebra Combined with Anterior Controllable Antedisplacement and Fusion for Cervical Ossification of the Posterior Longitudinal Ligament Extending to C2 Segment

We sought to introduce an anterior surgical technique for cervical ossification of posterior longitudinal ligament (OPLL) extending to C2. A total of 29 patients with multilevel OPLL extending to C2 underwent surgery from January 2016 to January 2019. The rationale of our surgical technique is to transect the ossified ligament at the level of C2/3, dividing OPLL into 2 parts. OPLL behind the C2 vertebra is reserved as "focus exclusion," and OPLL below C2 is performed anterior controllable antedisplacement and fusion. Neurologic condition was evaluated using the Japanese Orthopaedic Association scoring system and its improvement ratio. Radiologic assessment included type and extent of OPLL, occupying rate, thickness and length of ossified mass, and curvature of spinal cord. Surgery- and implant-related complications were recorded. The mean Japanese Orthopaedic Association score increased from 9.4 to 15.8 points at last follow-up, with a significant improvement (P < 0.01). The mean preoperative length of the ossified mass behind C2 was 15.4 mm, and its thickness was 2.2 mm, with no significant progression at last follow-up (15.3 mm and 2.2 mm, P > 0.05). There was also no statistical difference in OPLL thickness at the largest occupying rate level between preoperation and last follow-up (7.4 mm vs. 7.3 mm, P > 0.05). Four patients presented with cerebrospinal fluid leakage, 1 with screw displacement, and 1 with dysphagia. For patients with cervical OPLL extending to C2, exclusion of ossified ligaments behind C2 combined with anterior controllable antedisplacement and fusion below C2 is an effective and alternative technique.

How much space of the spinal canal should be restored by hoisting the vertebrae–OPLL complex for sufficient decompression in anterior controllable antedisplacement and fusion? A multicenter clinical radiological study

Anterior controllable antedisplacement and fusion (ACAF) is a novel surgical technique for the treatment of ossification of the posterior longitudinal ligament (OPLL). Its prognostic factors for decompression have not been well studied. Additionally, no detailed radiological standard has been set for hoisting the vertebrae-OPLL complex (VOC) in ACAF. To identify the possible prognostic factors for decompression outcomes after ACAF for cervical OPLL, to determine the critical value of radiological parameters for predicting good outcomes, and to establish a radiological standard for hoisting the VOC in ACAF. This was a retrospective multicenter study. A total of 121 consecutive patients with OPLL who underwent ACAF at a point between January 2017 and June 2018 at any one of seven facilities and were monitored for at least 1 year afterward were enrolled in a multicenter study. Japanese Orthopedic Association (JOA) scores, recovery rate (RR) of neurologic function, and surgical complications were used to determine the effectiveness of ACAF. Patients were divided into two groups according to their RR for neurologic function. Patients with an RR of ≥50% and an RR of <50% were designated as having good and poor decompression outcomes, respectively. The relationship between various possible prognostic factors and decompression outcomes was assessed by univariate and multivariate analysis. The receiver operating characteristic curve was used to determine the optimal cutoff value of the radiological parameters for prediction of good decompression outcomes. Next, the patients were redivided into three groups according to the cutoff value of the selected radiological parameter (postoperative anteroposterior canal diameter [APD] ratio). Patients with postoperative APD ratios of ≤80.7%, 80.7%-100%, and ≥100% were defined as members of the incomplete, optimal, and excessive antedisplacement groups, respectively. Differences in decompression outcomes among the three groups were compared to verify the reliability of the postoperative APD ratio and assess the necessity of excessive antedisplacement. Multivariate logistic regression analysis showed that patients' age at surgery (odds ratio [OR]=1.18; 95% confidence interval [CI]=1.08-1.29; p<.01) and postoperative APD ratio (OR=0.83; 95% CI=0.77-0.90; p<.01) were independently associated with decompression outcomes. The optimal cutoff point of the postoperative APD ratio was calculated at 80.7%, with 86.2% sensitivity and 73.5% specificity. There were no significant differences in the postoperative JOA scores and RRs between the excessive antedisplacement group and optimal antedisplacement group (p>.05). However, a lower incidence of cerebrospinal fluid leakage and screw slippage was observed in the optimal antedisplacement group (p<.05). Patients' age at surgery and their postoperative APD ratio are the two prognostic factors of decompression outcomes after ACAF. The postoperative APD ratio is also the most accurate radiological parameter for predicting good outcomes. Our findings suggest that it is essential for neurologic recovery to restore the spinal canal to more than 80.7% of its original size (postoperative APD ratio >80.7%), and restoration to less than its original size (postoperative APD ratio <100%) will help reduce the incidence of surgical complications. This may serve as a valuable reference for establishment of a radiological standard for hoisting the VOC in ACAF.

Analysis of the Incompletely Hoisted Vertebrae in the Anterior Controllable Antedisplacement and Fusion Surgery: Causes and Prevention.

Anterior controllable antedisplacement and fusion (ACAF) has been reported to be a safe and effective technique. However, incompletely hoisted vertebrae (IV) were found in the postoperative images. This study aims to analyze the causes and prevention of IV. The ACAF-treated case series subjects were retrospectively reviewed. The vertebrae were separated into the IV group and completely hoisted vertebrae (CV) group according to the gap between the vertebrae and plate. The radiographic data, degree of cervical lordosis, bone mineral density, number of hoisted vertebrae, operative time, blood loss, and Japanese Orthopaedic Association score were compared between the patients with IV and the patients without IV. A total of 248 vertebrae were hoisted in the enrolled patients. Intervertebral disc height in the IV group was 3.7±0.4 mm, which is significantly lower than that in the CV group. The anterior or posterior overhanging lip, osteoporosis, and oblique osteotomy troughs and hinges existing after osteotomy were found to be impingements preventing the hoisting of the vertebrae. There were no differences in the age, sex, degree of cervical lordosis, number of hoisted vertebrae, and neurological improvement rate between the groups of patients with and without IV. Lower intervertebral space height and impingements preventing hoisting were found to be possible causes of IV in ACAF. Measures to prevent the problem should be carried out.