Anterior Controllable Antedisplacement And Fusion Research Articles

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

ABSTRACTObjectWith 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.MethodsThis 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.ResultsBased 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).ConclusionA 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.

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.

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.

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.

Analysis of the spinal cord angle for severe cervical ossification of the posterior longitudinal ligament: comparison between anterior controllable antedisplacement and fusion (ACAF) and posterior laminectomy.

To investigate the changes of spinal cord angle between anterior controllable antedisplacement and fusion (ACAF) and posterior laminectomy in treating severe ossification of the posterior longitudinal ligament (OPLL). Seventy-one patients with cervical OPLL were enrolled. Patients in this study were divided into group A and group P. Japanese Orthopaedic Association (JOA) score was utilized to evaluate the neurological function. Radiological assessments included the spinal cord angle, Cobb angle, and area of the spinal cord. Surgery-related complications were also recorded. At the final follow-up, patients in group A had better recovery of local and whole cord angle, and the area of the cord than those in group P (all p < 0.05). A strong correlation between the change of local cord angle and the recovery of the spinal cord area was observed (r = - 0.867, p < 0.05). In addition, patients in group P had worse Cobb angle (9.15° ± 1.10°) than in group A (18.58° ± 0.73°) (p < 0.05). The final mean JOA score and its improvement rate were better in the group A than in group P (p < 0.05). During the follow-up, 15.15% patients in group P experienced surgery-related complications and 7.89% in group A. This present study revealed that ACAF can achieve better recovery of the expansion of the spinal cord, spinal cord alignment, and Cobb angle, with better postoperative JOA score and less complications, compared with posterior laminectomy in treating severe cervical OPLL. These slides can be retrieved under Electronic Supplementary Material.

Risk assessment of vertebral artery injury in anterior controllable antedisplacement and fusion (ACAF) surgery: a cadaveric and radiologic study.

We have introduced a novel surgery technique named anterior controllable antedisplacement and fusion (ACAF) for the treatment of ossification of the posterior longitudinal ligament. As reported, the satisfactory postoperative outcome can be attributed to the larger decompression width. However, it may associate with high prevalence of vertebral artery injury (VAI) theoretically. Thus, assessment of the vulnerability of vertebral artery in ACAF is of great importance. Computed tomographic scan data of 28 patients were retrospectively studied. Seven radiographic parameters were evaluated: uncinate process (UP) tips distance, transverse foramen (TF)-UP tips distance, TF-LWL (the ipsilateral limited wedging line) distance, the limited distance of lateral decompression, the maximum oblique angle of LWL, TF-LWG (the lateral wall of groove) distance, and width of groove. Eleven fresh cadaveric spines undergoing ACAF surgery were also studied. Two anatomic parameters were evaluated: width of groove and LWG-TF distance. The UP tips distance increased from C3 to C6 and tended to be larger in males. The UP tip-TF distance and LWL-TF distance were smallest at C4, but both were larger than 2mm. Maximum oblique angle decreased from C3 to C6. Postoperatively, both radiographic and cadaveric measurements showed the width of groove was larger than UP tips distance, but LWG-TF distance was larger than 2mm in all levels. UP can be used as anatomical landmarks to avoid VAI during ACAF surgery. Radiographic and cadaveric measurements verified the safety of ACAF surgery, even for those cases with wedging and lateral slotting.

Skip corpectomy and fusion (SCF) versus anterior controllable antedisplacement and fusion (ACAF): which is better for patients with multilevel cervical OPLL?

The aim of this study was to compare the clinical efficacy and radiological outcomes of skip corpectomy and fusion (SCF) with anterior controllable antedisplacement and fusion (ACAF) for treating multilevel ossification of the posterior longitudinal ligament (OPLL). 62 patients with multilevel OPLL who had undergone SCF or ACAF were analyzed retrospectively. Types of OPLL, occupying ratio (OR), Japanese Orthopaedic Association (JOA) score, Recovery Rate (RR), Neck Disability Index (NDI) score, Cobb's angles of C2-C7, operation time, blood loss, hospital stay, ratings for fusion assessment and complications were recorded and assessed. Postoperative C2-C7 Cobb's angle (11.1 ± 3.2° vs. 13.7 ± 2.5°; P < 0.05), NDI scores at final follow-up (14.3 ± 1.6 vs. 13.3 ± 1.3; P < 0.05), and rate of cerebral fluid (CSF) leakage (5, 16.7% vs. 0,0%; P < 0.05) were significantly better in the ACAF group. At 6months, bone graft fusion rate was significantly greater in the ACAF group (24.75% vs. 15.50%; P < 0.05). Surgical treatment of multilevel OPLL by SCF or ACAF showed no significant differences in clinical outcomes, with the exception of better NDI scores at final follow-up in ACAF. In addition, ACAF is better than SCF in terms of early bone graft fusion rate, lordotic curvature improvement, risk of CSF leakage.

How to Avoid Postoperative Remaining Ossification Mass in Anterior Controllable Antedisplacement and Fusion Surgery

ObjectivesTo retrospectively review the cases with ossification of the posterior longitudinal ligament (OPLL) treated with anterior controllable antedisplacement and fusion (ACAF). Patients with postoperative remaining ossification mass (PROM) are analyzed to figure out the causes and preventions of this problem.MethodsA total of 115 patients were included. PROM was identified as remaining OPLL existed in the spinal canal other than included in the vertebral-OPLL complex on postoperative computed tomography. The Japanese Orthopaedic Association scoring system was used to evaluate the neurologic status. Surgery-related complications such as cerebrospinal fluid (CSF) leakage and spinal cord or nerve injury were all recorded. The patients with the PROM group and those without the PROM group were compared.ResultsThere were 14 patients with wide-base OPLL (12.2%) and 10 patients (8.7%) with PROM among the 115 patients with OPLL. The 10 patients with PROM were all with wide-base OPLL. The average improvement rate of Japanese Orthopaedic Association score in patients without PROM was significantly larger than that in patients with PROM (69.5 ± 22.6% vs. 36.7 ± 22.0, P < 0.01). Incidence rate of postoperative CSF leakage and neural deterioration were significantly higher in patients with PROM than that in patients without PROM (CSF leakage, 40.0% vs. 5.9%; neural deterioration, 50.0% vs. 3.0%). No other complications were observed.ConclusionsThe occurrence of PROM might cause complications and poor neural function recovery in patients treated with ACAF. Surgical techniques should be noted to avoid PROM in ACAF surgery.

Surgical Outcomes After Anterior Controllable Antedisplacement and Fusion Compared with Single Open-Door Laminoplasty: Preliminary Analysis of Postoperative Changes of Spinal Cord Displacements on T2-Weighted Magnetic Resonance Imaging

This retrospective cohort study aimed to investigate the change of spinal cord displacements and the occurrence of C5 palsy between anterior controllable antedisplacement and fusion (ACAF) (group A) and single open-door laminoplasty (group L). From January 2016 to December 2017, a total of 80 patients with cervical ossification of the posterior longitudinal ligament (OPLL) were enrolled. All patients underwent computed tomography and magnetic resonance imaging. The types and extent of OPLL, spinal cord rotation, deviation angle, and distance between the vertebral arteries line and spinal cord (DVS) were measured. Patients with postoperative C5 palsy were recorded. Neurologic function was evaluated by Japanese Orthopaedic Association (JOA) score. Three days after surgery, patients in group A had better recovery (6.7° ± 2.4°) of spinal cord rotation than group L (3.1° ± 0.8°; P < 0.05). Deviation angle showed similar changes to spinal cord rotation. At the final follow-up, patients in group A had decreased DVS (11.0 ± 0.7 mm), whereas patients in group L had increased DVS (15.1 ± 0.8 mm) compared with preoperation (P < 0.05). Five patients (1in group A and 4 in group L) developed postoperative C5 palsy (P > 0.05). Patients in group A had a higher JOA score at the final follow-up than those in group L (P < 0.05). ACAF could achieve in situ decompression in terms of spinal cord rotation, deviation angle, and spinal cord shift with better clinical outcomes and relatively lower incidence of C5 palsy compared with single open-door laminoplasty.

Anterior Controllable Antedisplacement and Fusion as Revision Surgery After Posterior Decompression Surgery in Patients with Ossification of the Posterior Longitudinal Ligament

The aim of the present study was to evaluate the surgical outcomes of anterior controllable antedisplacement and fusion (ACAF) as a revision surgery after posterior decompression surgery (PDS) in patients with ossification of the posterior longitudinal ligament (OPLL). From June 2016 to May 2017, 15 patients (7 men; 8 women) had undergone ACAF as revision after PDS. The Japanese Orthopaedic Association (JOA) score was used to evaluate the pre- and postoperative neurological function. The kappa line and complications were also evaluated. The 15 patients were followed up for 15.1 ± 1.8 months (range, 12-18). The mean interval between the initial PDS and revision ACAF was 40.3 ± 11.3 months (range, 24-62). The JOA score improved from 8.9 ± 1.6 (range, 5-11) before revision ACAF to 13.9 ± 1.6 (range, 11-16) at the final follow-up evaluation (P < 0.05). The JOA recovery rate was 61.9% ± 15.8% (range, 37.5%-90.9%). The kappa line of 7 patients improved from negative values to positive values after ACAF. Five complications (33.3%) developed in 5 patients. No instrument failure or neurological deterioration was observed during the follow-up period. In the present study, the outcomes of ACAF for revision surgery for OPLL were satisfactory. ACAF could improve neurological function significantly and is an alternative surgical procedure for revision of PDS for OPLL.

Anterior Controllable Antedisplacement Fusion as a Choice for Ossification of Posterior Longitudinal Ligament and Degenerative Kyphosis and Stenosis: Postoperative Morphology of Dura Mater and Probability Analysis of Epidural Hematoma Based on 63 Patients

We studied the postoperative morphology of the dura mater and analyzed the probability of epidural hematoma (EH) after anterior controllable antedisplacement and fusion (ACAF). A total of 63 patients with a diagnosis of ossification of the posterior longitudinal ligament (OPLL) and degenerative kyphosis and stenosis (DKS) had undergone ACAF from 2016 to 2017. All these patients had undergone cervical plain films, computed tomography, and magnetic resonance imaging (MRI). The operation duration, blood loss, and hospital stay were estimated. Radiological assessments included the occupying rate, OPLL type and extent, kyphotic angle, decompression width, and postoperative area of the spinal canal. On sagittal MRI, the postoperative morphology of dura mater was observed. The Japanese Orthopaedic Association scoring system was used to evaluate neurological status. EH and other surgery-related complications were recorded. Of the 63 patients, 39 had OPLL and 24 had DKS. All the patients were followed up for 3-18 months (average, 12.5). The mean decompression width and postoperative spinal canal area were 18.7 ± 1.1 mm and 167.7 ± 34.6 mm2 in the OPLL group and 17.9 ± 0.9 mm and 263.1 ± 46.9 mm2 in the DKS group, respectively. On sagittal MRI, the dura mater was classified into 4 types according to its morphology (dune, ladder, wave, and mixed type), protecting the spinal cord as would a suspensory tent. No patient presented with EH. The mean postoperative Japanese Orthopaedic Association score at the last follow-up examination was significantly better than preoperatively. The dura mater can protect the spinal cord like a suspensory tent after ACAF. The occurrence of EH is rare when ACAF is used to treat OPLL and DKS.