Baorong He

Posterior atlantoaxial fixation: a review of all techniques

BACKGROUND CONTEXT Posterior atlantoaxial fixation is an effective treatment for atlantoaxial instability. Great advancements on posterior atlantoaxial fixation techniques have been made in the past decades. However, there is no article reviewing all the posterior atlantoaxial fixation techniques yet. PURPOSE The aim was to review the evolution and advancements of posterior atlantoaxial fixation. STUDY DESIGN This was a literature review. METHODS The application of all posterior fixation techniques in atlantoaxial stabilization, including wiring techniques, interlaminar clamp fixation, transarticular fixation, screw-plate systems, screw-rod systems, and hook-screw systems, are reviewed and discussed. Recent advancements on the novel technique of atlantoaxial fixation are described. The combination of the C1 and C2 screws in screw-rod systems are described in detail. RESULTS All fixation techniques are useful. The screw-rod system appears to be the most popular approach. However, many novel or modified fixation methods have been introduced in recent years. CONCLUSIONS Great advancements on posterior atlantoaxial fixation techniques have been made in the past decades. The wiring technique and interlaminar clamps technique have fallen out of favor because of the development of newer and superior fixation techniques. The C1-C2 transarticular screw technique may remain the gold standard for atlantoaxial fusion, whereas screw-rod systems, especially the C1 pedicle screw combined with C2 pedicle/pars screw fixation, have become the most popular fixation techniques. Hook-screw systems are alternatives for atlantoaxial fixation.

The Efficiency of Zero-profile Implant in Anterior Cervical Discectomy Fusion: A Prospective Controlled Long-term Follow-up Study.

Study Design: A prospective controlled study. Objective: The aim of this study was to compare the safety and efficacy of the zero-profile device with that of an anterior cervical plate and cage in patients undergoing anterior cervical discectomy and fusion (ACDF). Summary of Background Data: A series of studies have indicated that anterior instruments produce good clinical results during ACDF. However, common implants are associated with a high rate of postoperative complications. A cervical stand-alone cage with integrated fixation for zero-profile segmental stabilization has been developed to solve this problem. Materials and Methods: A total of 46 patients with cervical radiculopathy or myelopathy were randomly treated with an anterior plate and a cage or a new zero-profile implant between September 2009 and April 2010. Patients were followed for 2 years. The operation time, blood loss, exposure to radiation, the Japan Department of Orthopedics Association (JOA) score, pain Visual Analogue Score (VAS), and dysphagia score were recorded. Results: The operation was completed successfully in 46 patients. Twenty-three patients received an anterior plate and cage (control group) and 23 patients received the new zero-profile implant (test group). Analysis of postoperative data at all protocol-defined intervals demonstrated improvement in all clinical outcomes for both the groups when compared with the corresponding preoperative data. No significant difference in VAS and JOA score was found in the 2 treatment groups. The test group had a greater reduction in dysphagia at all follow-up intervals, compared with the control group. No adjacent segment degeneration was found in the test group, whereas 4 patients in the control group developed degeneration in adjacent segments (P=0.045). Both the groups had no adverse events associated with the implant or implant surgery. Conclusions: The Zero-P implant is a viable alternative to ACDF in patients with persistently symptomatic, single-level cervical disk disease. The procedure requires more technical requirements than traditional plates.

C2 Nerve Dysfunction Associated with C1 Lateral Mass Screw Fixation

The C1 lateral mass screw technique is widely used for atlantoaxial fixation. However, C2 nerve dysfunction may occur as a complication of this procedure, compromising the quality of life of affected patients. This is a review of the topic of C2 nerve dysfunction associated with C1 lateral mass screw fixation and related research developments. The C2 nerve root is located in the space bordered superiorly by the posterior arch of C1, inferiorly by the C2 lamina, anteriorly by the lateral atlantoaxial joint capsule, and posteriorly by the anterior edge of the ligamentum flavum. Some surgeons suggest cutting the C2 nerve root during C1 lateral mass screw placement, whereas others prefer to preserve it. The incidence, clinical manifestations, causes, management, and prevention of C2 nerve dysfunction associated with C1 lateral mass screw fixation are reviewed. Sacrifice of the C2 nerve root carries a high risk of postoperative numbness, whereas postoperative nerve dysfunction can occur when it has been preserved. Many surgeons have been working hard on minimizing the risk of postoperative C2 nerve dysfunction associated with C1 lateral mass screw fixation.

Psoralidin suppresses osteoclastogenesis in BMMs and attenuates LPS-mediated osteolysis by inhibiting inflammatory cytokines

Abstract Psoralidin is a metabolic product from the seed of psoraleacorylifolia, possessed anti‐inflammatory and immunomodulatory effects. We speculated that psoralidin might impact osteoclastogenesis and bone loss. By using both in vitro and in vivo studies, we observed psoralidin strongly inhibited RANKL induced osteoclast formation during preosteoclast cultures, suggesting that it acts on osteoclast precursors to inhibit RANKL/RANK signaling. At the molecular level, by using MAPKs specific inhibitors (U‐0126, SB‐203580 and SP‐600125) we demonstrated that psoralidin markedly abrogated the phosphorylation of p38, ERK, JNK. Moreover, the RANKL induced NF‐&kgr;B/p65 phosphorylation and I‐&kgr;B degradation were significantly inhibited by psoralidin. Further, psoralidin significantly suppressed osteoclastogenesis marker genes of TRAP, Cathepsin K and OSCAR. These were accompanied by the decreased expression of c‐Fos and NFATc1 transcription factors. Consistent with in vitro results, our in vivo and serologic studies showed psoralidin inhibited lipopolysaccharide induced bone resorption by suppressing the inflammatory cytokines: TNF‐&agr; and IL‐6 expression, as well as the ratio of RNAKL: OPG. These results collectively suggested that psoralidin could represent a novel therapeutic strategy for osteoclast‐related disorders, such as rheumatoid arthritis and postmenopausal osteoporosis. HighlightsPsoralidin suppress RANKL‐induced osteoclast formation, bone resorption, and F‐actin ring formation.Psoralidin inhibit RANKL‐mediated MAPKs and NF‐&kgr;B signaling pathway.Psoralidin decrease the expression of osteoclastogenesis marker genes and transcription factors.Psoralidin can suppress LPS‐induced osteoporosis in a mouse model.

Posterior Approach in Treating Sacral Fracture Combined With Lumbopelvic Dissociation

Type III Denis fracture of the sacrum is rare clinically, constituting approximately 16% of all sacral fractures. Because it is often complicated with neurologic injuries, treatment is crucial and difficult. Several surgical options are available for the treatment of type III Denis sacral fracture with lumbopelvic dissociation. The authors report 21 patients admitted to the hospital from February 2002 to May 2012 who had type III Denis sacral fracture combined with lumbopelvic dissociation. All of the patients were treated with posterior sacral lamina decompression, sacral nerve root decompression, fracture reduction, an integrated lumbopelvic internal fixation system, and posterolateral fusion. The authors recorded pre- and postoperative complications, fracture reduction, bone graft healing, and improvements in neurologic function, according to the Gibbons grading standard. The average surgical time was 190 minutes (range, 170-210), and the average amount of intraoperative bleeding was 960 mL (range, 930-1500). No intraoperative complications occurred. Twelve patients had complete recovery of neurologic function; 5 patients showed great improvement except for foot drop and impaired lower limb sensation; and 4 patients showed no improvement in lower limb, bladder, and rectum function. Gibbons grade decreased from an average of 3.43±0.51 before surgery to 1.76±1.09 at the last follow-up. Deep infections were noted in 2 cases, and in 1 case, vertebral screw loosening was observed 1 year postoperatively. Surgical reduction with lumbopelvic fixation is an ideal method for treating type III Denis sacral fracture with neurologic injury and lumbopelvic dissociation.

Prospective, Self-controlled, Comparative Study of Transposterior Arch Lateral Mass Screw Fixation and Lateral Mass Screw Fixation of the Atlas in the Treatment of Atlantoaxial Instability.

Study Design: A prospective self-controlled study. Objective: The aim of the present study was to compare the application and clinical outcomes of transposterior arch lateral mass screw and lateral mass screw fixation of the atlas in the treatment of atlantoaxial instability. Summary of Background Data: Atlas posterior screw fixation techniques comprise transposterior arch lateral mass screw fixation and lateral mass screw fixation. Previous studies have focused mainly on the feasibility of the anatomy and the biomechanics of the methods. Methods: From June 2006 to February 2011, 66 patients with atlantoaxial instability were randomly assigned for treatment with transposterior arch lateral mass screw or lateral mass screw fixation of the atlas, combined with axis pedicle screw fixation. Patients were followed up regularly. The operation time, blood loss, intraoperative complications, Japan Department of Orthopedics Association Score, visual analog scale score, and bone fusion rates were recorded. Results: The operation was successful in all 66 cases, with all patients showing improvement in clinical symptoms. There were significant differences in operation time and blood loss between the 2 groups (P<0.001). The mean follow-up time was 49 months. At the final follow-up, the Japan Department of Orthopedics Association score was significantly better than the preoperative score (mean, 13.5; P<0.05). The mean postoperative improvement rate was 88.2% and the mean visual analog scale score was 1.9; both results were significant as compared with preoperative results (P<0.05). Bone fusion was achieved within 6 months after operation. No screw loosening, shifting, breakage, or atlantoaxial instability was observed. Six patients with atlas lateral mass screw placement had burst bleeding of C1–C2 venous plexus during surgery. Five patients had immediate pain and numbness at the occipitocervical region. Conclusions: Atlas transposterior arch lateral mass screw fixation is less invasive, simple, has fewer complications, and offers good fixation results for atlantoaxial instability as compared with lateral mass screw fixation.

One-stage anterior release and reduction with posterior fusion for treatment of irreducible atlantoaxial dislocation

Objective:  To analyze the approach and feasibility of one‐stage anterior release and reduction with posterior fusion for irreducible atlantoaxial dislocation.

Single-stage Anterior Release and Sequential Posterior Fusion for Irreducible Atlantoaxial Dislocation.

Study Design:A retrospective study. Objective:To introduce the method of single-stage anterior release and reduction with posterior fusion in irreducible atlantoaxial dislocation (IAAD) and to evaluate the clinical effects of this surgery. Summary of Background Data:In previous clinical studies, several techniques have been introduced to manage IAAD. But all these treatments have intrinsic disadvantages. A single-stage anterior release and reduction with posterior fusion can offer a new alternative which can avoid these disadvantages. Methods:From January 2003 to January 2009, 22 cases of IAAD were diagnosed consecutively. Anterior atlantoaxial release was performed through anterior retropharyngeal approach, after traction reduction conducted on the monitoring of C-arm fluoroscopy. C1–C2 were then fixed posteriorly and fused by single stage. Neurological status was evaluated using the Japanese Orthopaedic Association scoring system. Results:All patients were observed for an average of 32 months, ranging from 15 to 40 months. All cases achieved anatomic reduction and solid fusion. The Japanese Orthopaedic Association score of 12 patients with myelopathy improved from 8.3 to 13.9, 6 months postoperatively, and the mean improving rate was 87.5%. No graft or implant-related complications were observed in any patient during the entire follow-up period. Conclusions:The method of single-stage anterior release and reduction with posterior fusion is an effective method for management of IAAD, proving its value as a technique for achieving complete reduction with solid bony fusion.

The feasibility of inserting a C1 pedicle screw in patients with ponticulus posticus: a retrospective analysis of eleven patients

BackgroundPonticulus posticus is a common anatomic variation that can be mistaken for a broad posterior arch during C1 pedicle screw placement. When the atlas lateral mass screws are placed via the posterior arch, injury to the vertebral artery may result. To our knowledge, there are few clinical studies that have analyzed the feasibility of C1 pedicle screw fixation in patients with ponticulus posticus, in clinical practice.PurposeTo evaluate the feasibility of inserting a C1 pedicle screw in patients with ponticulus posticus.MethodsBetween January 2008 and January 2012, 11 consecutive patients with atlantoaxial instability, and with a ponticulus posticus at C1, underwent posterior fusion surgery in our institution. According to preoperative computed tomography (CT) reconstruction, a complete ponticulus posticus was found unilaterally in nine patients and bilaterally in two. Postoperative CT reconstructive imaging was performed to assess whether C1 pedicle screw placement was successful. Patients were followed up at regular intervals and evaluated for symptoms of ponticulus posticus syndrome.ResultsThirteen C1 pedicles (atlas vertebral artery groove), each with a complete ponticulus posticus, were successfully inserted with thirteen 3.5- or 4.0-mm diameter pedicle screws, without resection of the bony anomaly. No intraoperative complications (venous plexus, vertebral artery, or spinal cord injury) occurred. The mean follow-up period was 21 (range 14–30) months. Postoperative CT reconstructive images showed that all 13 pedicle screws were inserted in the C1 pedicles without destruction of the atlas pedicle cortical bone. In the follow-up period, none of the patients demonstrated clinical symptoms of ponticulus posticus syndrome or developed bone fusion.ConclusionThree-dimensional CT imaging should be considered prior to C1 pedicle screw fixation in patients with ponticulus posticus, to avoid mistaking the ponticulus posticus for a widened dorsal arch of the atlas. If there is no ponticulus posticus syndrome preoperatively, C1 pedicle screw fixation can be successfully performed without removing the bony anomaly.

Anterior cervical discectomy and fusion versus posterior fixation and fusion of C2-3 for unstable hangman's fracture.

Study Design: This was a retrospective study. Objective: To compare the efficacy and safety between anterior cervical discectomy and fusion (ACDF) and posterior fixation and fusion (PFF) for treating unstable hangman’s fracture. Summary of Background Data: In previous clinical study, ACDF and PFF have been introduced to manage unstable hangman’s fracture. However, it remains unknown which approach is superior. Methods: Between January 2006 and May 2011, 44 patients with unstable hangman’s fracture underwent either ACDF or PFF. The operation time, blood loss, surgical complications, and postoperative drainage were compared. Neurologic function was evaluated using the ASIA scale and neck pain was assessed using the Visual Analogue Scale (VAS) score. Rates of fracture heeling and bone fusion were also studied. Results: Follow-up was completed for 38 patients. Twenty-four cases underwent ACDF and 14 cases received PFF. The operation was successful in all 38 cases. The mean operative time, estimated blood loss, and postoperative drainage were significantly shorter or less for the ACDF group than the PFF group (P<0.01). No surgical complication was reported in the ACDF group. Excessive bleeding due to injury to the venous plexus occurred in 3 cases in the PFF group. The VAS score in the 2 groups was significantly lower than their respective preoperative score (P<0.01), but there was no difference between the 2 groups (P>0.05). Solid fusion was achieved with no implant failure in all cases 6 months postoperatively. At the final follow-up, 8 cases with ASIA C or D grade improved to E grade. Conclusions: The anterior procedure seems to be superior to the posterior approach for unstable hangman’s fracture as it is a less invasive and simpler procedure with fewer complications and is especially indicated for cases with no medullary canal in C2 pedicles and traumatic C2–3 disk herniation compressing the spinal cord.